3 of The Top 60 Second Binary Option Trading Strategies ...

# /r/Peloton Pre-TDF Survey 2020

Gentlemen, Ladies and those otherwise addressed - we know you've been waiting for a good thing, and the survey results are finally ready!
The answers were collected from you all during August 2020 with 1428 unique replies. That's a participation of 0.5% of all subscribers! That's really not too bad, when you keep in mind how popular these kind of surveys are. But we here at /peloton want to show you that this is all about presenting the information in the subreddit to cater better to our audience!
Updated after a few hours to include some more historical data the final edit that for some reason wasn't copied properly
Year 2013 2014 2015 2016 2018 Mar 2018 Aug 2019 2020
Results 2013-06-12 2014-06-25 2015-08-07 2016-11-17 2018-03-06 2018-08-20 2019-07-22 2020-10-12
Replies 351 598 1395 892 630 928 986 1428
Without further ado, let's get cracking on the response

You and Cycling

1. Where do you live?

Country 2015 2016 2018 Mar 2018 Aug 2019 2020
USA 32% 28.3% 22.84% 25.32% 20.23% 24.59%
UK 18.6% 17.6% 14.70% 20.13% 15.48% 14.80%
Netherlands 6.4% 9.4% 11.50% 11.58% 10.01% 11.01%
Germany 3.73% 3.4% 4.95% 6.39% 7.84% 6.65%
Denmark 3.9% 3.6% 4.31% 3.79% 7.64% 5.79%
Belgium 3.8% 2.7% 8.15% 3.57% 5.78% 5.36%
France 2.01% 1.08% 2.88% 2.27% 5.26% 3.50%
Canada 4.9% 7% 6.39% 4.22% 4.95% 4.50%
Australia 5.2% 4.7% 3.83% 4.00% 4.33% 3.93%
Slovenia 0.73% 0.32% 1.30% 1.14% 2.14%
Norway 2.58% 1.8% 1.60% 1.95% 2.58% 1.86%
Sweden 1.08% 1.09% 1.44% 1.41% 1.75% 1.43%
Ireland 1.00% 1.09% 1.44% 1.19% 0.72% 1.36%
Portugal 1.65% 1.8% 2.40% 1.52% 1.34% 1.14%
Italy 1.45% 1.44% 0.65% 1.03% 1.07%
Largely the same picture as ever, with the US leading the way, the UK in second and then a sliding scale of Europeans countries. Slovenia continues to pick its way up the pile for obvious reasons!
World Map to demonstrate

2. What's your age?

u17 17-19 20-25 26-30 31-35 36-40 41-50 51+ Total
2015 2.22% 12.04% 41.51% 24.66% 10.68% 4.87% 2.94% 1.08% 1395
2016 1.5% 8.9% 40.8% 24% 12% 5.4% 5.2% 2% 887
2018 Mar 1% 7.1% 33.5% 27.4% 16.2% 7% 5.7% 2.1% 617
2018 Aug 1.7% 9% 33.9% 26.4% 15.5% 7% 5% 1.5% 905
2019 1.5% 6.6% 33.2% 27.5% 16.4% 7.1% 5.8% 2% 972
2020 1.3% 6.8% 31.7% 28% 16.6% 7.2% 5% 2.5% 1420
Pretty much the same as last year, with the usual reddit demographics of majority 20 somethings dominating.

3. What's your gender?

'13 '14 '15 '16 '18 (1) '18 (2) '19 '20
Male 97.2% 97% 94.9% 93.4% 93.3% 93.6% 95.1% 94.9%
Female 2.8% 2.7% 4.8% 5.3% 5.3% 5.4% 3.7% 4.8%
Other - 0.33% 0.29% 0.78% 0.76% - -
Non-Binary - - - - 0.64% 0.99% 1.2% 0.4%
More normality here for reddit.

4. How much of the men's season do you watch/follow?

Type March '18 (%) August '18 (%) 2019 (%) 2020 (%)
Grand Tours 84.7 92.0 90.2 87.3
Monuments 79.1 74.9 79 75.9
WT Stage races 67.4 62.4 70.5 71.7
WT One day races 73.3 59.8 62.3 60.7
Non WT Stage races 32.6 16.7 17.4 25
Non WT One day races 34.8 13.7 17.4 20.7
Literally everything I can consume 35.9 18.1 21.1 27.1
Whilst GT following may be down (somehow), all the lower level stuff is up, which makes sense considering how desperate we have been for any racing during the season shutdown.

5. Do you maintain an interest in women's professional road racing?

Do you maintain an interest in women's professional road racing? '19 '20
Yes 49.8 49.2
No 50.2 50.8
Still very much a half/half interest in women's cycling on the subreddit.

6. How much of the women's season do you follow?

The following is true for the half of you that follows womens cycling.
How Much %
Just the biggest televised events 63.15%
Most of the live televised/delayed coverage stuff 29.08%
All televised racing 5.09%
Down to .Pro & beyond 2.69%

7. How long have you been watching cycling?

How Long %
Under a year 2,95%
1-3 years 19,50%
4-6 years 19,85%
7-9 years 14,10%
10-12 years 13,81%
13-15 years 7,15%
15-20 years 10,73%
20-25 years 6,17%
25 years + 5,75%
Simplified the years a little this time, but whilst we have a fair number of newbies, most people have picked the sport up since around 2013/14.

Sporting Favourites

8. Do you have like/dislike feelings about WT teams?

Once more, 14.4% of people really don't have feelings on the subject.
Of those that do:
AG2R Astana Bahrain Bora CCC Cofidis Quick-Step EF FDJ
Like 352 213 127 770 156 116 847 724 423
Meh 775 620 773 415 889 896 310 448 700
Dislike 52 356 263 31 112 141 71 37 53
Karma 300 -143 -70 739 44 -25 776 677 370
Israel Lotto Michelton Movistar NTT Ineos Jumbo Sunweb Trek UAE
Like 135 364 517 231 101 304 925 279 383 118
Meh 740 764 626 646 931 414 282 805 765 734
Dislike 302 40 52 326 121 562 53 97 42 331
Karma -167 324 465 -95 -20 -258 872 182 341 -213
So, the most popular team this year is Jumbo-Visma, followed by Quick-Step & Bora-hansgrohe. Least popular are Ineos & UAE.
As per usual, no one cares about NTT & CCC, with nearly 81% of users rating NTT as meh. Pretty damning stuff.
Lastly, we have the usual historical comparison of how teams have fared over time, normalised to respondents to that question on the survey.
Things to note then, firstly that the Astana redemption arc is over, seeing them back in the negative, maybe Fulgsangs spring issues helped aid that? The petrodollar teams of UAE & Bahrain are stubbornly negative too, with Israel keeping up the Katusha negative streak. Meanwhile, at the top end, EF & Jumbo go from strength to strength, whilst some others like Sunweb are sliding over time - their transfer policies no doubt helping that.

10. Do you ride a bike regularly?

Answer 2018Mar 2018Aug 2019 2020
For fun 61.5% 63.4% 59.9% 62.9%
For fitness 59.3% 59.6% 54.8% 59.8%
For commuting 46% 46% 45.6% 40%
For racing 20.6% 20.6% 15.9% 17.7%
No, I don't 14.2% 12.9% 14.8% 13.6%
Still a fairly small group of racers out of all of us

11. Out of the sports you practice, is cycling your favourite?

Yes No
58,29% 41,71%
A new addition to the survey prompted by a good point last time, just over half of us rate cycling as the favourite sport we actually do.

12. What other sports do you follow?

Sport #
Association Football / Soccer 50.78%
Formula 1 35.81%
American Football 26.27%
Basketball 22.46%
Track & Field 17.58%
Esports (yes, this includes DotA) 17.30%
Rugby 14.27%
Skiing 14.12%
Ice Hockey 13.63%
Baseball 12.15%
Motorsports (Not including F1) 10.59%
Cricket 10.52%
Tennis 9.53%
Chess 8.97%
Triathlon 8.69%
Biathlon 8.12%
Snooker 7.06%
Golf 6.92%
Swimming 6.85%
Ski Jumping 6.78%
Climbing 5.72%
Martial Arts 5.65%
Handball 5.44%
Darts 5.01%
Speed Skating 5.01%
Football always tops the charts, and Formula 1 continues to rank extremely highly among our userbase. Those who have a little following below 5% include Sailing, Fencing, Surfing, Boxing & Ultra-Running.
Other cycling disciplines
Sport #
Cyclocross 22.10%
Track Cycling 14.34%
MTB 8.97%
BMX 1.20%

13. Out of the sports you follow, is cycling your favourite sport?

Yes No
61.79% 38,21%
Good. Makes sense if you hang out here.

Subreddit stats

14. How often do you participate in a /Peloton Race Thread whilst watching a race?

2015 2016 2018Mar 2018Aug 2019 2020
I always participate in Race Threads during races 2.8% 2% 2.2% 4% 2.5% 3%
I follow Race Threads during races 41.7% 36.7% 38.1% 42.1% 42.5% 38.9%
I often participate in Race Threads during races 16.8% 19% 16.5% 18.9% 15.2% 13%
I rarely/never participate in Race Threads during races 38.7% 41.3% 43.1% 35% 39.8% 45.1%
Slightly less invested than before, reverting back to an older trade.

15. How do you watch Races?

Method 2018Mar 2018Aug 2019 2020
Pirate Streams 62% 46.5% 50.2% 47.9%
Free Local TV 55.7% 64.5% 59.6% 53.9%
Desperately scrabbling for Youtube highlights 37.9% 30.2% 28.2% 24.9%
Paid Streaming services 32.3% 35.4% 38.3% 46.3%
Year on year, paid streaming services go up - the increasing availability of live content legally continues to improve, and so do the numbers on the survey.

16. Where else do you follow races live (in addition to watching them)?

Type 2018Mar 2018Aug 2019 2020
/Peloton race threads 86.2% 83.4% 80.2% 76.9%
Twitter 30.5% 34.7% 33.3% 38.3%
PCS Liveticker - - 30.2% 32%
Official tracker (if available) 24%
The Cyclingnews liveticker 26% 23.5% 21.5% 18.9%
Sporza (site/ticker) 1.89% 9.5% 10.8% 10.8%
NOS Liveblog - 6.8% 7% 9.2%
Steephill 0.52% 13.5% 10.2% 8.2%
/Peloton discord 6.5% 5.4% 7.5% 7.2%
Other cycling forums 15.1% 8.1% 7.6% 7%
feltet.dk - 2.2% 5.4% 5.2%
Facebook 3.8% 5.4% 4% 4.2%
BBC Ticker - 3.5% 2.1% 4.1%
DirectVelo - 1.3% 1.6% 1.8%
Non Cycling Forums - 1.3% 1.2% 1.2%
/cyc/ - 1.3% 1% 0.6%
/peloton IRC ~0 0.8% 0.4% 0.5%
The PCS liveticker continues to have a strong following, whilst the cyclingnews ticker slowly slides into less usage over time.

17. Do you use /Peloton mostly in classic reddit or redesign when on the desktop?

Type 2018 Aug 2019 2020
Classic 75.1% 67.2% 46.2%
Redesign 24.9% 32.8% 53.8%
Time to abandon ship. The end has come.

18. With what version of reddit do you browse the sub?

Version 2019 2020
Official App 17.9 31.1
Desktop Classic 37.8 25.8
3rd Party App 18.3 17.2
Mobile Web 12.4 14.7
Desktop Redesign 13.7 11.2
Phone browsing is very much in vogue.

19. How did you find the sub?

How %
Through other forms of reddit, f.e. /bicycling 48.33%
Too long - can't remember 38.65%
Google search 9,11%
My friend told me 2,28%
I wanted to talk about my exercise bike 0.78%
Twitter 0.5%
Lantern Rouge Youtube 0.28%

Other bits and bobs

20. Did you think back in March we would see any more racing this year?

Yes No
52,81% 47,19%
Despite the threat, we have seen racing again

21. Will we manage to fulfill the rest of the UCI calendar without further Covid-19 issues postponing more races?

Yes No
25.3% 74.7%
Sorry to you 25%, Amstel, Roubaix & a bunch of other races have falled foul of COVID-19 related cancellations.

22. When did you become aware of Alexander Foliforov?

When %
Before the 2016 Giro 3,25%
22nd May, 2016 15,55%
On /pelotonmemes in 2020 21,13%
Who? 60,07%
If you didn't know of the man, watching him demolish the Giro field in 2016 on the stage 15 ITT should help to gain understanding

23. Who will win the 2020 Tour de France?

Rider %
Roglic 52,12%
Bernal 16,57%
Pinot 9,24%
Dumoulin 7,9%
N.Quintana 2,82%
Pogacar 1,41%
Richie Porte 0,35%
We can safely say that most of us were wrong about this one.
That's not a lot of confidence in Richie Porte either, the man who was to finish on the third spot of the podium. Alexander Foliforov (0,23%) had just a tiny number of votes less, and that man wasn't even in the race.

24. What for you was the defining cycling moment of the previous decade?

We had a lot of brilliant suggestions, but these were the clear five favourites when we tabulated the results.
Honorable mentions go to the Giro 2018, which had Tom Dumoulin winning, and of almost identical fascination to many of you - Tom Dumoulin going on someones porta-potty in the middle of the stage.
Little bit of recency bias perhaps, but that's better than ignoring that this was for the last decade and firmly insisting Tom Boonens 2005 WC win was the biggest thing. Special shoutout to almost all the Danes present in /peloton who voted for Mads Pedersens WC win last year. It's an understandable reaction.

25. Any suggestions for the Survey?

New Questions
We promise to feature one of these suggestions in the next survey
Suggestions
We will try to implement this. But it will also skew results.
About the Survey
The subscribers are torn on Women's cycling, nearly a 50/50 split there as the survey showed - The moderators at /peloton are firmly in the "more cycling is better" basket, and we will continue to get as good coverage of womens cycling as possible.
Are you trying to give the moderators PTSD? Because this is how you give the moderators PTSD.

26. Any suggestions for the sub?

ALSJFLKAJSLDKJAØLSJKD:M:CSAM)=#/()=#=/")¤=/)! - Your moderator seems to be out of function. Please stand by while we find you a new moderator
The Weekly threads are great for these types of questions, where several people can contribute and build up once it is understood which information is relevant.
Our experience is that "limited" will never be so, if we're going to moderate it fairly. Moderating is not a popularity contest, but believe it or not, we're actually trying to be as fair as possible. and for that, we need rules that are not subjective. Unless you have a stationary exercise bike.
All of these are good suggestions, but remember that all of you can also contribute - The mods are sometimes stretched thin, specially in the middle of hectic race schedules. It's easier if one of you has a way to contact a rider or a person of interest and can facilitate the initial communication.
We've worked on this! The Official Standard is now as follows: [Race Thread] 202x Race Name – Stage X (Class)
This sounds as a nice community project for the after-season, and hopefully many of you subscribers can contribute.
Come with suggestions on how to tidy it up!
We have chastised all the mods. They are now perfectly trained in gender-neutral pronouns. Be well, fellow being.
If we can implement this for hard liquor, you know we will.
The spoiler rule is one that is discussed frequently - in general - some users absolutely hate it, but a majority love it. Perhaps we'll include a question in the next survey to see how this divide is exactly.
We actually do - whenever there is a matter of life or death, we think public information is more important than a spoiler rule. But at the same time, we try to collect all the different posts into one main thread, so to keep things focused and letting very speculative posts meet with hard evidence from other sources.
This is a tough ask of the internet. While we can agree that voting should be done accordingly to what insights they bring, not subjective opinions, it is very hard to turn that type of thinking around. We can ask of you, our subscribers, that you please think twice about hitting that downvote button, and only do so because of you think a post is factually incorrect, not because it differs with your own subjective opinion.
That's the primary analysis of the survey! Feel free to contribute with how you experience things here!
submitted by PelotonMod to peloton [link] [comments]

nginx reverse proxy configuration settings?

Hey all,
After recently working through my nginx reverse proxy configuration, I noticed mine, while working as expected, could be structured much cleaner than it currently is.
So I'm curious about two things
  1. How others have structured their nginx.conf, sites-enabled/default, conf.d/jellyfin.conf. and any other config files they may have. It seems the best practice is to define each area within its own config file. For example, http headers configured in conf.d/http_headers.conf and included in nginx.conf
  2. What specific settings do others use for both security and performance for jellyfin - obviously the jellyfin docs have nginx settings listed, but curious what others do beyond these.
For context, I run a local static website along with proxying to jellyfin and I'm sure I could be doing things better than I currently am.
Here's my nginx.conf for example:
## ================================= ## to test configuration for errors ## run: gixy /etc/nginx.conf ## ================================= user www-data; worker_processes auto; pid /run/nginx.pid; include /etc/nginx/modules-enabled/*.conf; events { worker_connections 1024; multi_accept on; } http { charset utf-8; sendfile on; tcp_nopush on; tcp_nodelay on; server_tokens off; log_not_found off; types_hash_max_size 2048; # size Limits & Buffer Overflows client_body_buffer_size 128K; client_header_buffer_size 16k; client_max_body_size 32M; large_client_header_buffers 4 16k; # timeouts client_body_timeout 10; client_header_timeout 10; keepalive_timeout 5 5; send_timeout 10; server_names_hash_bucket_size 128; server_name_in_redirect off; # MIME include /etc/nginx/mime.types; default_type application/octet-stream; # logging access_log /valog/nginx/access.log; error_log /valog/nginx/error.log; # Diffie-Hellman parameter for DHE ciphersuites ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # SSL Settings ssl_session_cache shared:le_nginx_SSL:10m; ssl_session_timeout 1d; ssl_session_tickets off; ssl_prefer_server_ciphers on; ssl_protocols TLSv1.2 TLSv1.3; ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384; # OCSP Stapling ssl_stapling on; ssl_stapling_verify on; resolver 8.8.8.8 8.8.4.4 valid=60s; resolver_timeout 5s; # virtual Host Configs include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-enabled/*; # gzip Settings gzip on; gzip_http_version 1.1; gzip_vary on; gzip_disable "MSIE [1-6]\.(?!.*SV1)"; gzip_proxied any; gzip_comp_level 1; gzip_min_length 10240; gzip_buffers 16 8k; # what gzip will compress gzip_types text/plain text/css text/xml application/json application/javascript application/rss+xml application/atom+xml image/svg+xml; } 
jellyfin.conf:
server { listen 80; listen [::]:80; server_name $webAddress; set $jellyfin 192.168.20.203; # only domain name requests allowed if ($host !~ ^($webAddress)$ ) { return 444; } # only get,head,post requests allowed if ($request_method !~ ^(GET|HEAD|POST)$ ) { return 444; } # Redirect to HTTPS if ($host = $webAddress) { return 302 https://$server_name$request_uri; } return 404; } server { listen 443 ssl http2; listen [::]:443 ssl http2; server_name $webProxyAddress; set $jellyfin 192.168.20.203; # if they come here using HTTP, bounce them to the correct scheme error_page 497 https://$server_name:$server_port$request_uri; # only domain name requests allowed if ($host !~ ^($webProxyAddress)$ ) { return 444; } # only get,head,post requests allowed if ($request_method !~ ^(GET|HEAD|POST)$ ) { return 444; } # block download agents if ($http_user_agent ~* LWP::Simple|BBBike|wget) { return 403; } # SSL certs ssl_certificate ...; ssl_certificate_key ...; ssl_trusted_certificate ...; # HTTP security headers -- JELLY DOC add_header X-Frame-Options "SAMEORIGIN"; add_header X-XSS-Protection "1; mode=block"; add_header X-Content-Type-Options "nosniff"; add_header Content-Security-Policy "default-src https: data: blob:; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' https://www.gstatic.com/cv/js/sendev1/cast_sender.js; worker-src 'self' blob:; connect-src 'self'; object-src 'none'; frame-ancestors 'self'"; # HTTP security headers -- added for A+ rating add_header Strict-Transport-Security "max-age=63072000; includeSubdomains; preload"; add_header Referrer-Policy 'strict-origin'; add_header Expect-CT 'enforce, max-age=3600'; add_header Feature-Policy "autoplay 'none'; camera 'none'"; add_header Permissions-Policy 'autoplay=(); camera=()'; add_header X-Permitted-Cross-Domain-Policies none; # password security auth_basic "Restricted Content"; auth_basic_user_file /etc/nginx/.htpasswd; # proxy Jellyfin - copied fron jellyfin docs location / { proxy_pass http://$jellyfin:8096; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Forwarded-Protocol $scheme; proxy_set_header X-Forwarded-Host $http_host; # Disable buffering proxy gets very resource heavy proxy_buffering off; } # location block for Jellyfin /web - copied from jellyfin docs # purely for aesthetics location ~ ^/web/$ { proxy_pass http://$jellyfin:8096/web/index.html; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Forwarded-Protocol $scheme; proxy_set_header X-Forwarded-Host $http_host; } # websocket Jellyfin - copied from jellyfin docs location /socket { proxy_pass http://$jellyfin:8096; proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection "upgrade"; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Forwarded-Protocol $scheme; proxy_set_header X-Forwarded-Host $http_host; } } 
default
# set access rate limit: only allow 4 requests per second limit_req_zone $binary_remote_addr zone=one:10m rate=4s; # caching map map $sent_http_content_type $expires { default off; text/html epoch; text/css 5m; application/javascript 5m; ~image/ 5m; } server { listen 80 default_server; listen [::]:80 default_server; server_name $webAddress; # only get,head,post request allowed if ($request_method !~ ^(GET|HEAD|POST)$ ) { return 444; } # only domain name requests allowed if ($host !~ ^($webAddress)$ ) { return 444; } # redirect to HTTPS if ($host = $webAddress) { return 301 https://$host$request_uri; } return 404; } server { listen [::]:443 ssl http2; listen 443 ssl http2; server_name $webAddress; root /vawww/html; index index.html; # if they come here using HTTP, bounce them to the correct scheme error_page 497 https://$server_name:$server_port$request_uri; # redirect errors to 404 page error_page 401 403 404 /404.html; # set 503 error page error_page 503 /503.html; # only domain name requests allowed if ($host !~ ^($webAddress)$ ) { return 444; } # only get,head,post requests allowed if ($request_method !~ ^(GET|HEAD|POST)$ ) { return 444; } # block download agents if ($http_user_agent ~* LWP::Simple|BBBike|wget) { return 403; } # block some robots if ($http_user_agent ~* msnbot|scrapbot) { return 403; } # caching map expiration expires $expires; # cache location ~* /.(jpg|jpeg|png|gif|ico|pdf|png|ico|woff2|woff)$ { expires 5m; } # prevent deep linking location /img/ { valid_referers blocked $webAddress; if ($invalid_referer) { return 403; } referer_hash_bucket_size 128; } # SSL certs ssl_certificate ...; ssl_certificate_key ...; ssl_trusted_certificate ...; # HTTP security headers -- A+ rating add_header X-Frame-Options "SAMEORIGIN"; add_header X-XSS-Protection "1; mode=block"; add_header X-Content-Type-Options "nosniff"; add_header Content-Security-Policy "base-uri 'self'; default-src 'none'; frame-ancestors 'none'; style-src 'self'; font-src 'self' https://fonts.gstatic.com; img-src 'self'; script-src 'self' http https; form-action 'self'; require-trusted-types-for 'script'"; add_header Strict-Transport-Security "max-age=63072000; includeSubdomains; preload"; add_header Referrer-Policy 'strict-origin'; add_header Expect-CT 'enforce, max-age=3600'; add_header Feature-Policy "autoplay 'none'; camera 'none'"; add_header X-Permitted-Cross-Domain-Policies none; add_header Permissions-Policy 'autoplay=(); camera=()'; location /nginx_status { stub_status on; access_log off; # restrict access to lan allow 192.168.1.0/24; deny all; # security auth_basic "Restricted Content"; auth_basic_user_file /etc/nginx/.htpasswd; } location / { try_files $uri $uri/ =404; # rate limit limit_req zone=one burst=10 nodelay; } } 

submitted by famesjranko to jellyfin [link] [comments]

Results of the 2020 r/Zillennials sub census!

After 2 weeks the result of our sub census are here! We got over 150 responses, which is roughly 10% of readership. You can view the full results here.
Here are some highlights:
Biographical:
Life Stage:
Values and Beliefs:
Current Events
Pop Culture:
Nostalgia:
Other:
US-Specific Questions:
I hope you guys all enjoyed this and it will be fun to see how the results change the next time we do this! Feel free to discuss any of these results in the comments.
submitted by cafezinhos to Zillennials [link] [comments]

Setting up a domain controller using SAMBA 4 on Ubuntu 20.04 with both IPv4 and IPv6 support

(Note: this borrows heavily from https://github.com/thctlo/samba4/blob/mastefull-howto-Ubuntu18.04-samba-AD_DC.txt)
Prerequisites:
  1. Create your Ubuntu 20.04 server system. The details vary depending on what type of host it is. You’ll need to give it a static IP address and as such set up routing. Here’s my /etc/netplan/10-lxc.yaml file in case you’re using LXC:
    network: version: 2 ethernets: eth0: dhcp4: false dhcp6: false addresses: [10.0.0.2/16] gateway4: 10.0.0.1 nameservers: search: - example.com addresses: - 8.8.8.8 
    DHCP6 will need to be set to true if you set your router to provide DHCP6 for IPv6 addresses otherwise it can be set to false and your host will use router advertisements to configure itself. (IPv6 is wonderfully easy!)
    Set the timezone. If using an installer without a GUI you'll need to do this manually, try this:
    timedatectl set-timezone America/New_York 
    1.1 If using LXC, make sure your container is privileged. From the host, type something like:
    lxc stop dc1 sudo lxc config edit dc1 
    Add the following under, and indented to show it's a child of, 'config:'
    raw.lxc: |- lxc.cap.drop = lxc.cap.drop = sys_module mac_admin mac_override security.privileged: "true" 
    It's a YAML file so make sure the indenting is followed as above. These are necessary to make domain provisioning and NTP work.
    Restart and presumably go back in using these commands:
    lxc start dc1 lxc shell dc1 
  2. Set the name – set the shortname using hostnamectl
    hostnamectl set-hostname dc1 
    and edit /etc/hosts so that the first line looks something like this:
    127.0.1.1 dc1.example.com dc1 
  3. Set up a user with sudo permissions to administer the machine. You don’t want to be logged in as root most of the time, and most of the time you don’t even need to use ‘sudo’ for this.
  4. Install openssh-server
    apt-get install openssh-server 
    If you want, you can continue the rest of this remotely from the login you created.
  5. Install SAMBA
    apt install samba winbind libnss-winbind libpam-winbind ntp bind9 binutils ldb-tools krb5-user 
    At this stage you will probably be asked for your Kerberos settings. IMPORTANT: TYPE THE KERBEROS DOMAIN (EXAMPLE.ORG) IN UPPERCASE. Any other questions you should be able to guess the answers for or they may be obvious anyway.
    systemctl disable nmbd smbd winbind systemctl stop nmbd smbd winbind systemctl unmask samba-ad-dc systemctl enable samba-ad-dc 
  6. Set up NTP
    install -d /valib/samba/ntp_signd -m 750 -o root -g ntp cat << EOF >> /etc/ntp.conf # ###### Needed for Samba 4 ###### # extra info, in the restrict -4 or -6 added mssntp. # Location of the samba ntp_signed directory ntpsigndsocket /valib/samba/ntp_signd # EOF sed -i 's/restrict -4 default kod notrap nomodify nopeer noquery limited/restrict -4 default kod notrap nomodify nopeer noquery limited mssntp/g' /etc/ntp.conf sed -i 's/restrict -6 default kod notrap nomodify nopeer noquery limited/restrict -6 default kod notrap nomodify nopeer noquery limited mssntp/g' /etc/ntp.conf systemctl restart ntp systemctl status ntp ntpq -p 
    Some of the above may show error messages under LXC, if so verify you did 1.1 above. If you still get messages, don't panic.
  7. Tweak Kerberos
    All we really need is the domain part for Kerberos, so:
    cd /etc sudo mv krb5.conf krb5.conf.ORG sudo head -n2 krb5.conf.ORG | tee krb5.conf 
    You may also want to edit the krb5.conf file and add these lines to the end to maximize compatibility with other Kerberos implementations:
    default_tgs_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5 default_tkt_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5 permitted_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 rc4-hmac des-cbc-crc des-cbc-md5 
  8. Set up Samba
    Clear the cobwebs
    rm /valib/samba/*.tdb rm /vacache/samba/*.tdb rm /vacache/samba/browse.dat mv /etc/samba/smb.conf /etc/samba/smb.conf.ORIG 
  9. Create the domain
    If you're using LXC, and you didn't set it up as a privileged container (see 1.1), this is where that will go wrong. So recheck you did 1.1 properly. if you get an error message.
    samba-tool domain provision --use-rfc2307 --realm=EXAMPLE.COM --domain=EXAMPLE --dns-backend=BIND9_DLZ 
    On my system at least this generated a lot of garbage debugging type output but it did end up creating the domain. It will give you a virtually unusable Administrator account password, don't worry we're going to change it. But there's a couple of things we'll do before that.
  10. Set up BIND
    Edit /etc/bind/named.conf.options, to look something like this:
    options { forwarders { 8.8.8.8; }; dnssec-validation auto; listen-on-v6 { any; } notify no; empty-zones-enable: no; tkey-gssapi-keytab "/valib/samba/bind-dns/dns.keytab"; allow-transfer {10.0.0.2;}; } 
    Edit /etc/bind/named.conf.local, and add the line:
    include "/valib/samba/bind-dns/named.conf"; 
    Edit /valib/samba/bind-dns/named.conf, and uncomment out the last entry (yes, I know you're running a more recent version of BIND, that DLL works with it, trust me.)
    Restart BIND
    systemctl restart named 
    Confirm it works - use dig (install it using apt-get install bind9-dnsutils if it wasn't installed already)
    dig @10.0.0.2 www.google.com 
    Finally point this VM to its own DNS server. Edit /etc/netplan/ and change 8.8.8.8 there to 10.0.0.2 and reboot.
  11. Make the administrator account usable
    You probably want to set a password on the latter you'll remember. To do this, use this command:
    sudo samba-tool user setpassword Administrator 
    That's a helpful command to know anyway - anyone with root access to the DC can set passwords here too. If you get a complexity error, you can disable that check using this command do it again:
    sudo samba-tool domain passwordsettings set --complexity=off 
    You can test this all works using:
    kinit Administrator 
    If your password is accepted, not only did it all work, but you're now logged in and can stop using sudo with most SAMBA commands. If you add -k yes to the end of any samba-tool command it will accept you as authorized.
  12. Add a reverse DNS zone and set up DHCP.
    samba-tool dns zonecreate dc1.example.com 0.10.in-addr.arpa -k yes 
    For DHCP I'm going to offer three choices of how to set up DHCP in this environment: use your router's implementation, put one here, and put one here that does DNS updates.
    12.1 Your router
    If you're going to use your router's, you're all set. If you need to set up IP addresses for specific devices, set up the router to give them out (or just disable DHCP on your device itself and set the IP manually, outside of the range your DHCP server issues them), and, if you're not adding them to the domain, add DNS entries like this:
    samba-tool dns add dc1.example.com example.com mypc A 10.0.0.3 -k yes samba-tool dns add dc1.example.com 0.10.in-addr.arpa 3.0 PTR mypc.example.com -k yes 
    Devices that are added to the domain will have their DNS entries managed by SAMBA itself, you don't have to worry about them. If you add a static IP for a host and add DNS for it, you'll need to delete the DNS entries if you then decide to add it to your Active Directory domain.
    12.2 Local ISC DHCP Server
    The second option, running ISC DHCP, is mostly just as easy, it has some advantages that you can log activity and easily see, for example, what each device identified itself as by checking the logs. Again, just use samba-tool as in 12.1 to update IP addresses for static devices that haven't been joined to the network.
    Install isc-dhcp-server using:
    sudo apt-get install isc-dhcp-server 
    Then edit your /etc/dhcp/dhcpd.conf to look something like this:
    authoritative; ddns-update-style none; option subnet-mask 255.255.0.0; option broadcast-address 10.0.255.255; option time-offset 0; option routers 10.0.0.1; option domain-name "example.com"; option domain-name-servers 10.0.0.2; option netbios-name-servers 10.0.0.2; option ntp-servers 10.0.0.2; subnet 10.0.0.0 netmask 255.255.0.0 { range 10.0.1.1 10.0.127.255; default-lease-time -1; max-lease-time -1; } host mypc { hardware ethernet 40:50:60:70:80:90; fixed-address 10.0.0.3; option host-name "mypc"; } 
    "mypc" is an example of a static address, you can add as many host entries as you want.
    Finally, restart DHCP
    systemctl restart isc-dhcp-server 
    12.3 Local ISC Server with DNS updates
    This is what every lazy system administrator wants, and to be fair it can be helpful as long as you have full control over your own network. I cover some of the issues in my preview article. But it's dangerous - essentially you're giving any device that has access to your network authorization to add host records to your DNS server that point at it - at least, as long as it's for the DHCP IPv4 address they've been given. So a malicious entity could, for example, override "login.example.com" and point it at their server, which might be a problem if people go to http://login.example.com whenever they need to enter passwords to access secured content on your system. If nothing else it'd be easy to do a DoS attack. For anything other than a home network or a small office, you shouldn't do this. At all. But if it's your own network, and you administer it, and you monitor what gets plugged into it, then it can save some headaches.
    Given that usage profile, I'm going to make it slightly more insecure than Samba recommends, because Samba's recommended solution... doesn't work. The people who put it together are OK with it not working because in their view it doesn't break anything they themselves need, but it does break IPv6 and certain roaming scenarios, and it does result in error messages that you're going to forget the meaning of and implications of if you don't add something to your domain for a while.
    So here's the solution:
    Do everything in 12.2, but add the following lines to the end of /etc/dhcp/dhcpd.conf:
    on commit { set noname = concat("dhcp-", binary-to-ascii(10, 8, "-", leased-address)); set ClientIP = binary-to-ascii(10, 8, ".", leased-address); set ClientDHCID = concat ( suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,1,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,2,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,3,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,4,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,5,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,6,1))),2) ); set ClientName = pick-first-value(option host-name, config-option-host-name, client-name, noname); log(concat("Commit: IP: ", ClientIP, " DHCID: ", ClientDHCID, " Name: ", ClientName)); execute("/uslocal/bin/dhcp-dyndns.sh", "add", ClientIP, ClientDHCID, ClientName); } on release { set ClientIP = binary-to-ascii(10, 8, ".", leased-address); set ClientDHCID = concat ( suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,1,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,2,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,3,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,4,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,5,1))),2), ":", suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware,6,1))),2) ); log(concat("Release: IP: ", ClientIP)); execute("/uslocal/bin/dhcp-dyndns.sh", "delete", ClientIP, ClientDHCID); } on expiry { set ClientIP = binary-to-ascii(10, 8, ".", leased-address); log(concat("Expired: IP: ", ClientIP)); execute("/uslocal/bin/dhcp-dyndns.sh", "delete", ClientIP, "", "0"); } 
    Now go to Samba's Wiki and copy their script to /uslocal/bin/dhcp-dyndns.sh, and make it executable:
    sudo cp dhcp-dyndns.sh /uslocal/bin/ sudo chmod a+x /uslocal/bin/dhcp-dyndns.sh 
    Set up the dhcpduser:
    samba-tool user create dhcpduser --description="Unprivileged user for TSIG-GSSAPI DNS updates via ISC DHCP server" --random-password -k yes samba-tool user setexpiry dhcpduser --noexpiry -k yes samba-tool group addmembers DnsAdmins dhcpduser -k yes sudo samba-tool domain exportkeytab [email protected] /etc/dhcpduser.keytab sudo chown dhcpd.root /etc/dhcpduser.keytab sudo chmod 400 /etc/dhcpduser.keytab 
    Allow domain hosts (computers added to the domain) to manage their own DNS entries (but alas this command also means they can manage DNS in general):
    samba-tool dsacl set -k yes -H ldap://dc1.example.com --objectdn=CN=MicrosoftDNS,DC=DomainDnsZones,DC=example,DC=com "--sddl=(A;CI;RPWPCRCCDCLCLORCWOWDSDDTSW;;;DC)" 
    If you don't want to do the last bit, your options are limited. My advice is ask yourself why you don't like the idea, because your reasons almost certainly can be expanded to the entire concept of allowing DHCP to add DNS entries based upon self identified hosts. Consider instead doing 11.1 or 11.2.
And that's it. You can test everything's working by adding new sites to the domain. For Windows clients, Microsoft has the documentation. For Ubuntu, well, that's my next article.
submitted by squiggleslash to u/squiggleslash [link] [comments]

AJ ALMENDINGER

glimpse into the future of Roblox

Our vision to bring the world together through play has never been more relevant than it is now. As our founder and CEO, David Baszucki (a.k.a. Builderman), mentioned in his keynote, more and more people are using Roblox to stay connected with their friends and loved ones. He hinted at a future where, with our automatic machine translation technology, Roblox will one day act as a universal translator, enabling people from different cultures and backgrounds to connect and learn from each other.
During his keynote, Builderman also elaborated upon our vision to build the Metaverse; the future of avatar creation on the platform (infinitely customizable avatars that allow any body, any clothing, and any animation to come together seamlessly); more personalized game discovery; and simulating large social gatherings (like concerts, graduations, conferences, etc.) with tens of thousands of participants all in one server. We’re still very early on in this journey, but if these past five months have shown us anything, it’s clear that there is a growing need for human co-experience platforms like Roblox that allow people to play, create, learn, work, and share experiences together in a safe, civil 3D immersive space.
Up next, our VP of Developer Relations, Matt Curtis (a.k.a. m4rrh3w), shared an update on all the things we’re doing to continue empowering developers to create innovative and exciting content through collaboration, support, and expertise. He also highlighted some of the impressive milestones our creator community has achieved since last year’s RDC. Here are a few key takeaways:
And lastly, our VP of Engineering, Technology, Adam Miller (a.k.a. rbadam), unveiled a myriad of cool and upcoming features developers will someday be able to sink their teeth into. We saw a glimpse of procedural skies, skinned meshes, more high-quality materials, new terrain types, more fonts in Studio, a new asset type for in-game videos, haptic feedback on mobile, real-time CSG operations, and many more awesome tools that will unlock the potential for even bigger, more immersive experiences on Roblox.

Vibin’

Despite the virtual setting, RDC just wouldn’t have been the same without any fun party activities and networking opportunities. So, we invited special guests DJ Hyper Potions and cyber mentalist Colin Cloud for some truly awesome, truly mind-bending entertainment. Yoga instructor Erin Gilmore also swung by to inspire attendees to get out of their chair and get their body moving. And of course, we even had virtual rooms dedicated to karaoke and head-to-head social games, like trivia and Pictionary.
Over on the networking side, Team Adopt Me, Red Manta, StyLiS Studios, and Summit Studios hosted a virtual booth for attendees to ask questions, submit resumes, and more. We also had a networking session where three participants would be randomly grouped together to get to know each other.

What does Roblox mean to you?

We all know how talented the Roblox community is from your creations. We’ve heard plenty of stories over the years about how Roblox has touched your lives, how you’ve made friendships, learned new skills, or simply found a place where you can be yourself. We wanted to hear more. So, we asked attendees: What does Roblox mean to you? How has Roblox connected you? How has Roblox changed your life? Then, over the course of RDC, we incorporated your responses into this awesome mural.
📷
Created by Alece Birnbach at Graphic Recording Studio

Knowledge is power

This year’s breakout sessions included presentations from Roblox developers and staff members on the latest game development strategies, a deep dive into the Roblox engine, learning how to animate with Blender, tools for working together in teams, building performant game worlds, and the new Creator Dashboard. Dr. Michael Rich, Associate Professor at Harvard Medical School and Physician at Boston Children’s Hospital, also led attendees through a discussion on mental health and how to best take care of you and your friends’ emotional well-being, especially now during these challenging times.
📷
Making the Dream Work with Teamwork (presented by Roblox developer Myzta)
In addition to our traditional Q&A panel with top product and engineering leaders at Roblox, we also held a special session with Builderman himself to answer the community’s biggest questions.
📷
Roblox Product and Engineering Q&A Panel

2020 Game Jam

The Game Jam is always one of our favorite events of RDC. It’s a chance for folks to come together, flex their development skills, and come up with wildly inventive game ideas that really push the boundaries of what’s possible on Roblox. We had over 60 submissions this year—a new RDC record.
Once again, teams of up to six people from around the world had less than 24 hours to conceptualize, design, and publish a game based on the theme “2020 Vision,” all while working remotely no less! To achieve such a feat is nothing short of awe-inspiring, but as always, our dev community was more than up for the challenge. I’ve got to say, these were some of the finest creations we’ve seen.
WINNERS
Best in Show: Shapescape Created By: GhettoMilkMan, dayzeedog, maplestick, theloudscream, Brick_man, ilyannna You awaken in a strange laboratory, seemingly with no way out. Using a pair of special glasses, players must solve a series of anamorphic puzzles and optical illusions to make their escape.
Excellence in Visual Art: agn●sia Created By: boatbomber, thisfall, Elttob An obby experience unlike any other, this game is all about seeing the world through a different lens. Reveal platforms by switching between different colored lenses and make your way to the end.
Most Creative Gameplay: Visions of a perspective reality Created By: Noble_Draconian and Spathi Sometimes all it takes is a change in perspective to solve challenges. By switching between 2D and 3D perspectives, players can maneuver around obstacles or find new ways to reach the end of each level.
Outstanding Use of Tech: The Eyes of Providence Created By: Quenty, Arch_Mage, AlgyLacey, xJennyBeanx, Zomebody, Crykee This action/strategy game comes with a unique VR twist. While teams fight to construct the superior monument, two VR players can support their minions by collecting resources and manipulating the map.
Best Use of Theme: Sticker Situation Created By: dragonfrosting and Yozoh Set in a mysterious art gallery, players must solve puzzles by manipulating the environment using a magic camera and stickers. Snap a photograph, place down a sticker, and see how it changes the world.
OTHER TOP PICKS
HONORABLE MENTIONS
For the rest of the 2020 Game Jam submissions, check out the list below:
20-20 Vision | 20/20 Vision | 2020 Vision, A Crazy Perspective | 2020 Vision: Nyon | A Wild Trip! | Acuity | Best Year Ever | Better Half | Bloxlabs | Climb Stairs to 2021 | Double Vision (Team hey apple) | Eyebrawl | Eyeworm Exam | FIRE 2020 | HACKED | Hyperspective | Lucid Scream | Mystery Mansion | New Years at the Museum | New Year’s Bash | Poor Vision | Predict 2020 | RBC News | Retrovertigo | Second Wave | see no evil | Sight Fight | Sight Stealers | Spectacles Struggle | Specter Spectrum | Survive 2020 | The Lost Chicken Leg | The Outbreak | The Spyglass | Time Heist | Tunnel Vision | Virtual RDC – The Story | Vision (Team Freepunk) | Vision (Team VIP People ####) | Vision Developers Conference 2020 | Vision Is Key | Vision Perspective | Vision Racer | Visions | Zepto
And last but not least, we wanted to give a special shout out to Starboard Studios. Though they didn’t quite make it on time for our judges, we just had to include Dave’s Vision for good measure. 📷
Thanks to everyone who participated in the Game Jam, and congrats to all those who took home the dub in each of our categories this year. As the winners of Best in Show, the developers of Shapescape will have their names forever engraved on the RDC Game Jam trophy back at Roblox HQ. Great work!

‘Til next year

And that about wraps up our coverage of the first-ever digital RDC. Thanks to all who attended! Before we go, we wanted to share a special “behind the scenes” video from the 2020 RDC photoshoot.
Check it out:
It was absolutely bonkers. Getting 350 of us all in one server was so much fun and really brought back the feeling of being together with everyone again. That being said, we can’t wait to see you all—for real this time—at RDC next year. It’s going to be well worth the wait. ‘Til we meet again, my friends.
© 2020 Roblox Corporation. All Rights Reserved.

Improving Simulation and Performance with an Advanced Physics Solver

August

05, 2020

by chefdeletat
PRODUCT & TECH
📷In mid-2015, Roblox unveiled a major upgrade to its physics engine: the Projected Gauss-Seidel (PGS) physics solver. For the first year, the new solver was optional and provided improved fidelity and greater performance compared to the previously used spring solver.
In 2016, we added support for a diverse set of new physics constraints, incentivizing developers to migrate to the new solver and extending the creative capabilities of the physics engine. Any new places used the PGS solver by default, with the option of reverting back to the classic solver.
We ironed out some stability issues associated with high mass differences and complex mechanisms by the introduction of the hybrid LDL-PGS solver in mid-2018. This made the old solver obsolete, and it was completely disabled in 2019, automatically migrating all places to the PGS.
In 2019, the performance was further improved using multi-threading that splits the simulation into jobs consisting of connected islands of simulating parts. We still had performance issues related to the LDL that we finally resolved in early 2020.
The physics engine is still being improved and optimized for performance, and we plan on adding new features for the foreseeable future.

Implementing the Laws of Physics

📷
The main objective of a physics engine is to simulate the motion of bodies in a virtual environment. In our physics engine, we care about bodies that are rigid, that collide and have constraints with each other.
A physics engine is organized into two phases: collision detection and solving. Collision detection finds intersections between geometries associated with the rigid bodies, generating appropriate collision information such as collision points, normals and penetration depths. Then a solver updates the motion of rigid bodies under the influence of the collisions that were detected and constraints that were provided by the user.
📷
The motion is the result of the solver interpreting the laws of physics, such as conservation of energy and momentum. But doing this 100% accurately is prohibitively expensive, and the trick to simulating it in real-time is to approximate to increase performance, as long as the result is physically realistic. As long as the basic laws of motion are maintained within a reasonable tolerance, this tradeoff is completely acceptable for a computer game simulation.

Taking Small Steps

The main idea of the physics engine is to discretize the motion using time-stepping. The equations of motion of constrained and unconstrained rigid bodies are very difficult to integrate directly and accurately. The discretization subdivides the motion into small time increments, where the equations are simplified and linearized making it possible to solve them approximately. This means that during each time step the motion of the relevant parts of rigid bodies that are involved in a constraint is linearly approximated.
📷📷
Although a linearized problem is easier to solve, it produces drift in a simulation containing non-linear behaviors, like rotational motion. Later we’ll see mitigation methods that help reduce the drift and make the simulation more plausible.

Solving

📷
Having linearized the equations of motion for a time step, we end up needing to solve a linear system or linear complementarity problem (LCP). These systems can be arbitrarily large and can still be quite expensive to solve exactly. Again the trick is to find an approximate solution using a faster method. A modern method to approximately solve an LCP with good convergence properties is the Projected Gauss-Seidel (PGS). It is an iterative method, meaning that with each iteration the approximate solution is brought closer to the true solution, and its final accuracy depends on the number of iterations.
📷
This animation shows how a PGS solver changes the positions of the bodies at each step of the iteration process, the objective being to find the positions that respect the ball and socket constraints while preserving the center of mass at each step (this is a type of positional solver used by the IK dragger). Although this example has a simple analytical solution, it’s a good demonstration of the idea behind the PGS. At each step, the solver fixes one of the constraints and lets the other be violated. After a few iterations, the bodies are very close to their correct positions. A characteristic of this method is how some rigid bodies seem to vibrate around their final position, especially when coupling interactions with heavier bodies. If we don’t do enough iterations, the yellow part might be left in a visibly invalid state where one of its two constraints is dramatically violated. This is called the high mass ratio problem, and it has been the bane of physics engines as it causes instabilities and explosions. If we do too many iterations, the solver becomes too slow, if we don’t it becomes unstable. Balancing the two sides has been a painful and long process.

Mitigation Strategies

📷A solver has two major sources of inaccuracies: time-stepping and iterative solving (there is also floating point drift but it’s minor compared to the first two). These inaccuracies introduce errors in the simulation causing it to drift from the correct path. Some of this drift is tolerable like slightly different velocities or energy loss, but some are not like instabilities, large energy gains or dislocated constraints.
Therefore a lot of the complexity in the solver comes from the implementation of methods to minimize the impact of computational inaccuracies. Our final implementation uses some traditional and some novel mitigation strategies:
  1. Warm starting: starting with the solution from a previous time-step to increase the convergence rate of the iterative solver
  2. Post-stabilization: reprojecting the system back to the constraint manifold to prevent constraint drift
  3. Regularization: adding compliance to the constraints ensuring a solution exists and is unique
  4. Pre-conditioning: using an exact solution to a linear subsystem, improving the stability of complex mechanisms
Strategies 1, 2 and 3 are pretty traditional, but 3 has been improved and perfected by us. Also, although 4 is not unheard of, we haven’t seen any practical implementation of it. We use an original factorization method for large sparse constraint matrices and a new efficient way of combining it with the PGS. The resulting implementation is only slightly slower compared to pure PGS but ensures that the linear system coming from equality constraints is solved exactly. Consequently, the equality constraints suffer only from drift coming from the time discretization. Details on our methods are contained in my GDC 2020 presentation. Currently, we are investigating direct methods applied to inequality constraints and collisions.

Getting More Details

Traditionally there are two mathematical models for articulated mechanisms: there are reduced coordinate methods spearheaded by Featherstone, that parametrize the degrees of freedom at each joint, and there are full coordinate methods that use a Lagrangian formulation.
We use the second formulation as it is less restrictive and requires much simpler mathematics and implementation.
The Roblox engine uses analytical methods to compute the dynamic response of constraints, as opposed to penalty methods that were used before. Analytics methods were initially introduced in Baraff 1989, where they are used to treat both equality and non-equality constraints in a consistent manner. Baraff observed that the contact model can be formulated using quadratic programming, and he provided a heuristic solution method (which is not the method we use in our solver).
Instead of using force-based formulation, we use an impulse-based formulation in velocity space, originally introduced by Mirtich-Canny 1995 and further improved by Stewart-Trinkle 1996, which unifies the treatment of different contact types and guarantees the existence of a solution for contacts with friction. At each timestep, the constraints and collisions are maintained by applying instantaneous changes in velocities due to constraint impulses. An excellent explanation of why impulse-based simulation is superior is contained in the GDC presentation of Catto 2014.
The frictionless contacts are modeled using a linear complementarity problem (LCP) as described in Baraff 1994. Friction is added as a non-linear projection onto the friction cone, interleaved with the iterations of the Projected Gauss-Seidel.
The numerical drift that introduces positional errors in the constraints is resolved using a post-stabilization technique using pseudo-velocities introduced by Cline-Pai 2003. It involves solving a second LCP in the position space, which projects the system back to the constraint manifold.
The LCPs are solved using a PGS / Impulse Solver popularized by Catto 2005 (also see Catto 2009). This method is iterative and considers each individual constraints in sequence and resolves it independently. Over many iterations, and in ideal conditions, the system converges to a global solution.
Additionally, high mass ratio issues in equality constraints are ironed out by preconditioning the PGS using the sparse LDL decomposition of the constraint matrix of equality constraints. Dense submatrices of the constraint matrix are sparsified using a method we call Body Splitting. This is similar to the LDL decomposition used in Baraff 1996, but allows more general mechanical systems, and solves the system in constraint space. For more information, you can see my GDC 2020 presentation.
The architecture of our solver follows the idea of Guendelman-Bridson-Fedkiw, where the velocity and position stepping are separated by the constraint resolution. Our time sequencing is:
  1. Advance velocities
  2. Constraint resolution in velocity space and position space
  3. Advance positions
This scheme has the advantage of integrating only valid velocities, and limiting latency in external force application but allowing a small amount of perceived constraint violation due to numerical drift.
An excellent reference for rigid body simulation is the book Erleben 2005 that was recently made freely available. You can find online lectures about physics-based animation, a blog by Nilson Souto on building a physics engine, a very good GDC presentation by Erin Catto on modern solver methods, and forums like the Bullet Physics Forum and GameDev which are excellent places to ask questions.

In Conclusion

The field of game physics simulation presents many interesting problems that are both exciting and challenging. There are opportunities to learn a substantial amount of cool mathematics and physics and to use modern optimizations techniques. It’s an area of game development that tightly marries mathematics, physics and software engineering.
Even if Roblox has a good rigid body physics engine, there are areas where it can be improved and optimized. Also, we are working on exciting new projects like fracturing, deformation, softbody, cloth, aerodynamics and water simulation.
Neither Roblox Corporation nor this blog endorses or supports any company or service. Also, no guarantees or promises are made regarding the accuracy, reliability or completeness of the information contained in this blog.
This blog post was originally published on the Roblox Tech Blog.
© 2020 Roblox Corporation. All Rights Reserved.

Using Clang to Minimize Global Variable Use

July

23, 2020

by RandomTruffle
PRODUCT & TECH
Every non-trivial program has at least some amount of global state, but too much can be a bad thing. In C++ (which constitutes close to 100% of Roblox’s engine code) this global state is initialized before main() and destroyed after returning from main(), and this happens in a mostly non-deterministic order. In addition to leading to confusing startup and shutdown semantics that are difficult to reason about (or change), it can also lead to severe instability.
Roblox code also creates a lot of long-running detached threads (threads which are never joined and just run until they decide to stop, which might be never). These two things together have a very serious negative interaction on shutdown, because long-running threads continue accessing the global state that is being destroyed. This can lead to elevated crash rates, test suite flakiness, and just general instability.
The first step to digging yourself out of a mess like this is to understand the extent of the problem, so in this post I’m going to talk about one technique you can use to gain visibility into your global startup flow. I’m also going to discuss how we are using this to improve stability across the entire Roblox game engine platform by decreasing our use of global variables.

Introducing -finstrument-functions

Nothing excites me more than learning about a new obscure compiler option that I’ve never had a use for before, so I was pretty happy when a colleague pointed me to this option in the Clang Command Line Reference. I’d never used it before, but it sounded very cool. The idea being that if we could get the compiler to tell us every time it entered and exited a function, we could filter this information through a symbolizer of some kind and generate a report of functions that a) occur before main(), and b) are the very first function in the call-stack (indicating it’s a global).
Unfortunately, the documentation basically just tells you that the option exists with no mention of how to use it or if it even actually does what it sounds like it does. There’s also two different options that sound similar to each other (-finstrument-functions and -finstrument-functions-after-inlining), and I still wasn’t entirely sure what the difference was. So I decided to throw up a quick sample on godbolt to see what happened, which you can see here. Note there are two assembly outputs for the same source listing. One uses the first option and the other uses the second option, and we can compare the assembly output to understand the differences. We can gather a few takeaways from this sample:
  1. The compiler is injecting calls to __cyg_profile_func_enter and __cyg_profile_func_exit inside of every function, inline or not.
  2. The only difference between the two options occurs at the call-site of an inline function.
  3. With -finstrument-functions, the instrumentation for the inlined function is inserted at the call-site, whereas with -finstrument-functions-after-inlining we only have instrumentation for the outer function. This means that when using-finstrument-functions-after-inlining you won’t be able to determine which functions are inlined and where.
Of course, this sounds exactly like what the documentation said it did, but sometimes you just need to look under the hood to convince yourself.
To put all of this another way, if we want to know about calls to inline functions in this trace we need to use -finstrument-functions because otherwise their instrumentation is silently removed by the compiler. Sadly, I was never able to get -finstrument-functions to work on a real example. I would always end up with linker errors deep in the Standard C++ Library which I was unable to figure out. My best guess is that inlining is often a heuristic, and this can somehow lead to subtle ODR (one-definition rule) violations when the optimizer makes different inlining decisions from different translation units. Luckily global constructors (which is what we care about) cannot possibly be inlined anyway, so this wasn’t a problem.
I suppose I should also mention that I still got tons of linker errors with -finstrument-functions-after-inlining as well, but I did figure those out. As best as I can tell, this option seems to imply –whole-archive linker semantics. Discussion of –whole-archive is outside the scope of this blog post, but suffice it to say that I fixed it by using linker groups (e.g. -Wl,–start-group and -Wl,–end-group) on the compiler command line. I was a bit surprised that we didn’t get these same linker errors without this option and still don’t totally understand why. If you happen to know why this option would change linker semantics, please let me know in the comments!

Implementing the Callback Hooks

If you’re astute, you may be wondering what in the world __cyg_profile_func_enter and __cyg_profile_func_exit are and why the program is even successfully linking in the first without giving undefined symbol reference errors, since the compiler is apparently trying to call some function we’ve never defined. Luckily, there are some options that allow us to see inside the linker’s algorithm so we can find out where it’s getting this symbol from to begin with. Specifically, -y should tell us how the linker is resolving . We’ll try it with a dummy program first and a symbol that we’ve defined ourselves, then we’ll try it with __cyg_profile_func_enter .
[email protected]:~/src/sandbox$ cat instr.cpp int main() {} [email protected]:~/src/sandbox$ clang++-9 -fuse-ld=lld -Wl,-y -Wl,main instr.cpp /usbin/../lib/gcc/x86_64-linux-gnu/crt1.o: reference to main /tmp/instr-5b6c60.o: definition of main
No surprises here. The C Runtime Library references main(), and our object file defines it. Now let’s see what happens with __cyg_profile_func_enter and -finstrument-functions-after-inlining.
[email protected]:~/src/sandbox$ clang++-9 -fuse-ld=lld -finstrument-functions-after-inlining -Wl,-y -Wl,__cyg_profile_func_enter instr.cpp /tmp/instr-8157b3.o: reference to __cyg_profile_func_enter /lib/x86_64-linux-gnu/libc.so.6: shared definition of __cyg_profile_func_enter
Now, we see that libc provides the definition, and our object file references it. Linking works a bit differently on Unix-y platforms than it does on Windows, but basically this means that if we define this function ourselves in our cpp file, the linker will just automatically prefer it over the shared library version. Working godbolt link without runtime output is here. So now you can kind of see where this is going, however there are still a couple of problems left to solve.
  1. We don’t want to do this for a full run of the program. We want to stop as soon as we reach main.
  2. We need a way to symbolize this trace.
The first problem is easy to solve. All we need to do is compare the address of the function being called to the address of main, and set a flag indicating we should stop tracing henceforth. (Note that taking the address of main is undefined behavior[1], but for our purposes it gets the job done, and we aren’t shipping this code, so ¯\_(ツ)_/¯). The second problem probably deserves a little more discussion though.

Symbolizing the Traces

In order to symbolize these traces, we need two things. First, we need to store the trace somewhere on persistent storage. We can’t expect to symbolize in real time with any kind of reasonable performance. You can write some C code to save the trace to some magic filename, or you can do what I did and just write it to stderr (this way you can pipe stderr to some file when you run it).
Second, and perhaps more importantly, for every address we need to write out the full path to the module the address belongs to. Your program loads many shared libraries, and in order to translate an address into a symbol, we have to know which shared library or executable the address actually belongs to. In addition, we have to be careful to write out the address of the symbol in the file on disk. When your program is running, the operating system could have loaded it anywhere in memory. And if we’re going to symbolize it after the fact we need to make sure we can still reference it after the information about where it was loaded in memory is lost. The linux function dladdr() gives us both pieces of information we need. A working godbolt sample with the exact implementation of our instrumentation hooks as they appear in our codebase can be found here.

Putting it All Together

Now that we have a file in this format saved on disk, all we need to do is symbolize the addresses. addr2line is one option, but I went with llvm-symbolizer as I find it more robust. I wrote a Python script to parse the file and symbolize each address, then print it in the same “visual” hierarchical format that the original output file is in. There are various options for filtering the resulting symbol list so that you can clean up the output to include only things that are interesting for your case. For example, I filtered out any globals that have boost:: in their name, because I can’t exactly go rewrite boost to not use global variables.
The script isn’t as simple as you would think, because simply crawling each line and symbolizing it would be unacceptably slow (when I tried this, it took over 2 hours before I finally killed the process). This is because the same address might appear thousands of times, and there’s no reason to run llvm-symbolizer against the same address multiple times. So there’s a lot of smarts in there to pre-process the address list and eliminate duplicates. I won’t discuss the implementation in more detail because it isn’t super interesting. But I’ll do even better and provide the source!
So after all of this, we can run any one of our internal targets to get the call tree, run it through the script, and then get output like this (actual output from a Roblox process, source file information removed):
excluded_symbols = [‘.\boost.*’]* excluded_modules = [‘/usr.\’]* /uslib/x86_64-linux-gnu/libLLVM-9.so.1: 140 unique addresses InterestingRobloxProcess: 38928 unique addresses /uslib/x86_64-linux-gnu/libstdc++.so.6: 1 unique addresses /uslib/x86_64-linux-gnu/libc++.so.1: 3 unique addresses Printing call tree with depth 2 for 29276 global variables. __cxx_global_var_init.5 (InterestingFile1.cpp:418:22) RBX::InterestingRobloxClass2::InterestingRobloxClass2() (InterestingFile2.cpp.:415:0) __cxx_global_var_init.19 (InterestingFile2.cpp:183:34) (anonymous namespace)::InterestingRobloxClass2::InterestingRobloxClass2() (InterestingFile2.cpp:171:0) __cxx_global_var_init.274 (InterestingFile3.cpp:2364:33) RBX::InterestingRobloxClass3::InterestingRobloxClass3()
So there you have it: the first half of the battle is over. I can run this script on every platform, compare results to understand what order our globals are actually initialized in in practice, then slowly migrate this code out of global initializers and into main where it can be deterministic and explicit.

Future Work

It occurred to me sometime after implementing this that we could make a general purpose profiling hook that exposed some public symbols (dllexport’ed if you speak Windows), and allowed a plugin module to hook into this dynamically. This plugin module could filter addresses using whatever arbitrary logic that it was interested in. One interesting use case I came up for this is that it could look up the debug information, check if the current address maps to the constructor of a function local static, and write out the address if so. This effectively allows us to gain a deeper understanding of the order in which our lazy statics are initialized. The possibilities are endless here.

Further Reading

If you’re interested in this kind of thing, I’ve collected a couple of my favorite references for this kind of topic.
  1. Various: The C++ Language Standard
  2. Matt Godbolt: The Bits Between the Bits: How We Get to main()
  3. Ryan O’Neill: Learning Linux Binary Analysis
  4. Linkers and Loaders: John R. Levine
  5. https://eel.is/c++draft/basic.exec#basic.start.main-3
Neither Roblox Corporation nor this blog endorses or supports any company or service. Also, no guarantees or promises are made regarding the accuracy, reliability or completeness of the information contained in this blog.
submitted by jaydenweez to u/jaydenweez [link] [comments]

[META] The Rules and their Entirety

These are the rules, everything that pertains to everyone who wishes to make any sort of interaction within this sub. Per the last META, clarity has been given in regards to bulk-type sales. Since EVERYTHING is here for you all to read, we expect there to be less issues with rule infractions and general confusion as to what’s acceptable, and what isn’t. We devote our time and energy for this sub to continuously never reach a balance amongst the users.
Our goal is to ensure the subreddit itself sticks around, along with trying to keep the userbase from being taken advantage of. Our rules make sense to some, and none to others but they serve a purpose. Regardless of how you feel, these are the rules and it is expected they be followed. At the time this post becomes visible, all of what’s listed below will be enforced as a hard rule, no more wrist slaps or babysitting.

Reporting Rules

Here are the Subreddit Reportable violations. Violating these rules will get you a ban.

Reddit Rules:

Reddit Rules regarding Firearms
No firearm sales. No Ammunition sales. No primers or gunpowder, as they are considered explosives.
No selling or distributing of files related to 3D printed firearms.
If you have no idea what this is referring to, please educate yourself before posting anything related to 3D printing files by reading up on them at the following websites:
Firearms: A Firearm is considered the serialized receiver or assembly of a working firearm. If you are unsure if an item is prohibited, contact the mods prior to posting it.
80% lowers and completion kits are not included in this prohibition as they are not firearms yet.
Bump-Stocks are considered Machine Guns by the ATF and are therefore prohibited from trading on the sub.
Binary Triggers, Cranks, and Rubber bands and other such items are not (currently) affected by this prohibition (unless Admins change their minds later).
Explosives & Hazmat: Gunpowder and Live Primers are considered as explosives and Hazardous Materials and are therefore prohibited from trade.
Ammunition: Reddit Admins use the ATF definition of ammunition which is as follows:
The term “Ammunition” means ammunition or cartridge cases, primers, bullets, or propellant powder designed for use in any firearm. The term shall not include (a) any shotgun shot or pellet not designed for use as the single, complete projectile load for one shotgun hull or casing, nor (b) any unloaded, non-metallic shotgun hull or casing not having a primer. 27 § 478.11
Brass and projectiles posted here will result in an immediate suspension by Reddit Admins, so if we find it first we will remove it.
Any violation of these above rules will result in a ban by us, or a site-wide suspension by Admins and their Anti-Evil goosesteppers.
Anyone attempting to skirt Reddit Rules will be given a 7 day ban on the first offense, a 30 day ban on the second offense, and a permaban thereafter due to the fact that Admins will use the bad behavior of a few to justify shutting down the sub for good.

Posting Rules:

This sub is for private sales only. Vendors must post in Gundeals or GunAccessoryVendors
Clarification on Vendor Rule: Don't include links to your business website, we are not a referral system, do your business on here. Please see the Reddit Self Promotion page for details on that. Reddit admins don't like you cutting in on their ad revenue. We do not support VENDORS, I.E. if you buy another company's products in bulk (such as Magpul), and just act as a distributoreseller, your business is not welcome here. That is /GunDeals territory. If you have an FFL, you cannot do business on here because are considered a firearm business, and cannot solicit any transactions involving firearms.
The limit on bulk sales/bulk items is 10, that means 10 of the same individual item can be posted for sale or trade. If you have 10 Geissele triggers, but only 4 are flat and 6 are curved, that will still count as 10, as they're the same branded trigger and likely purchased at the same time. If there are 3 OD Green items and 7 FDE that are otherwise the same item, that still count as 10. If you post 10 items of the same in one day, 10 the next, and 10 the following day after that, that will be viewed as vendor activity. To keep such things from happening, it will be limited to one sale of this type, per user, per week. The ONLY EXCEPTION to this rule is old magazines, as it is common for users to purge off part of their mag collection.
Please follow these rules when creating a listing: Prefix your title with the transaction type:
[WTS] - Want To Sell
[WTB] - Want To Buy
[WTT] - Want To Trade
[GIFT] - Gun It Forward Tactically
Suffix your title with your state (e.g. (GA) or (NY)). This will help incentivize local sales and could impact shipping costs. Also, it could affect legality of some items such as magazines and those accessories deemed as "assault weapon" parts by certain states.
Postings should all follow this general format as an example: "[WTS] M16A2 Carry Handle - $60 (VA)". If you do not list the price in the title, ensure that it is listed in the comments. Include a Dollar sign ($) or the bot will remove it.
Postings without a price value may be removed after a period of time. WTB posts require valid offering prices, and will be removed if they do not have one.
Postings with prices such as "$1 for the bot" or "$1,000,000 for the bot" that are intended to bypass our rules and automated removal system instead of posting a valid price, will be removed and a temporary ban will be issued immediately.
Postings without pictures will be removed immediately, unless these posts are WTB.
Do not post an item for sale if you do not have it in your possession at the time of posting. This includes an item you may have purchased elsewhere, you decided you don’t want it and it’s on its way to you, but it has yet to arrive. If you don’t have it, don’t post it.
If you post stock images of an item in your WTS/WTT post, that will result in a temp ban if it is your first time doing so, possibly permanent if done on multiple occasions. If you post images of someone else’s photos for “your” item, this will be viewed as scamming tactics and you will receive a permaban, immediately.
If you drop your price, use the Price Drop/NSFW Tag. If your items sell, use the Complete/Spoiler tag. Please don't delete the price of an item if it sells, because that can be used by people in the future to gauge what similar items may be worth.
If your post does not receive the traction you're wanting, refrain from reposting within a 24 hour time frame. You may repost after the 24 hours has passed, and a price drop is not required, but encouraged. Deleting your post and reposting afterwards is viewed as trying to evade this rule. It will be met with removal and a temp ban, possibly longer if done more than once.
Want to Buy/Sell/Trade (WTB/WTS/WTT): These transactions all require a price value for the item. If a listing does not include a price it may be removed and re-listed once it is in compliance. Giving an unrealistic price to avoid this rule will be treated as a rule violation. Examples of this are "WTB scope, $1" or "WTT Upper, $9999". Additionally, you must list what you are looking for in [WTT] posts. Fielding offers, testing the waters or any other post attempt to try and skirt this rule will result in the post being removed.
Gifting items forward: (GIFT) If you have small odds and ends that aren't worth much and the cost of shipping is prohibitive, you are allowed to offer items for free. The gifter is allowed to request compensation for shipping only, and can request a flair upgrade in the feedback thread for the transaction. If the receiver pays for shipping, they can also request a flair upgrade, but if they get the item for free, no flair upgrades for the recipient. Flair upgrades of this type are limited in order to avoid abuse, i.e. giving away 20 A2 grips in order to get +20 rep is not authorized.
Accounts with 5 or less flair (you must have at least 6) on GAFS are NOT eligible to participate in giveaways, due to users from other subs coming to win stuff without ever participating in GAFS, or GAFS users making multiple new burner accounts to enter giveaways.
New accounts (under 30 days of age) are not able to create WTS or WTT ads, nor should they offer things for sale in the comments of other peoples' posts. To prevent scams, new users can only post Want to Buy threads. If you want to attempt to bypass this account age requirement, you must be able to provide moderators evidence of a good trading history on another reputable online forum, such as Calgunner or AR15.com where you can show a longstanding history of positive trade feedback. If this is completed, moderators may provide an exception and allow WTS/WTT posts to be submitted by new users, with a warning caveat to any potential buyers to avoid using risky payment methods until the seller has had a chance to develop a positive trading reputation.
Any new accounts that utilize this subreddit that create names that are similar to a mods (i.e. sxbbzxro, sxbzxxro, subzxro, etc.) may be removed from participating here due to the possibility of confusing/having the ability to manipulate users into thinking they are in fact a mod.
Price Checks (PC): Because PC listings were abused by many to bypass the price rule, fish for "best offers", and otherwise snipe sales, they have been disabled after overwhelming support from the community.
We have a feedback system in place. The current month's flair thread is On the Sidebar, and is usually Stickied at the top as well. Check there for the specific directions. DO NOT create a thread for a sale that has already happened, or has happened in a different sub/website/forum etc. The Flair system is only for feedback for exchanges in /GAFS. Any attempts to game the flair system will be seen as an attempt to establish trust for scam purposes, and will be banned accordingly.
Law Enforcement: Be aware, we do not offer exemptions to any individuals who may have LE credentials. Due to the difficulty of verifying employment, possible job changes, leaving/termination from said job, etc. we treat all users as civilians. Any local and federal laws apply to all individuals who utilize this subreddit. Read up and stay up-to-date on these laws and regulations, you will be expected to know and abide by them. Failure to do so may lead to a ban.
External Sales:
NO LINKS to your external sales on TacSwap, eBay, Facebook, Armslist, Gunbroker, etc. Sales in multiple locations are allowed, but don't just provide a link to sale elsewhere. Make your listing here. The only caveat to these rules is to show a price point elsewhere if someone here has an item that is grossly overpriced, or is looking for an item.
This sub is not a "highest bid gets the item" format. There are also no lotteries for items i.e. 10 chances at $10 each to purchase a $75 flashlight with a random number generated to pick the winner.
High Value or Counterfeit Items:
To deter the sale of counterfeit products, any item that is serialized must have a picture of the serial. As firearms are not allowed for sale here, this shouldn't present a privacy issue to anyone. This policy covers items such as EOTechs, Aimpoints, Trijicons, etc. Along with this, if you're selling anything that's "new-in-box", you must unseal it and show the contents of said box/package.
No Stolen Property. If you are selling a knockoff item, indicate that fact. Items such as bipods, BUIS, flashlights, holsters, and scopes/optics are known to have some gray market options. KAC USMC Stamped Rear Sights are not stolen property and are allowed on here, unless another member can provide proof from a DoD source that they are in fact considered stolen government property.
All GAFS logos, icons, banners and visual content related to this subreddit, belong to the moderator team. Do not create/manufacture/produce items with this content onto itself. It is forbidden to profit off the GAFS name, unless discussed with the modteam in advance and given permission.

Shipping/Insurance Rules:

The official policy is for the mods to not get involved with issues regarding lost packages, provided that the parties can prove it was actually lost. If you feel like insurance should be added to your transaction, please take care to add that before finalizing terms.

General Rules:

WARNING: Be aware of all state and federal laws that apply to you and any parties involved in a firearms-related transaction. You are responsible for knowing and following the law. This Subreddit and its staff are in no way responsible for informing you of the law, but will make every effort to do so. As a buyer, be familiar with your state/county/city rules. As a seller, do not knowingly sell prohibited items to areas that have laws against your items, such as certain capacity magazines. Any person, buyer, or seller, who knowingly solicits a trade that is illegal for them may be subject to a ban.
Respect all federal and local laws for any transaction you take part in. This includes federal drug laws. Drug activity tied to your account tied to any other issues is sufficient grounds for banning. Here is the ATF Letter that explains why any suspected drug activity, including marijuana, is grounds for immediate banning from the sub. Illegal gun activity such as unregistered SBRs, AOWs, destructive devices, DIAS or lightning links in your reddit profile (in or outside the sub) can be reason for banning. Do not spread bad information regarding laws.
Any item you post for sale is expected to be in your current possession. If this is not the case, you must specify this in the listing. Circumstances such as selling for a friend is allowed, but pictures of your items are required to be shared to the public. You do not need an imgur.com account in order to host pictures of your item on imgur, so that is not an excuse.
If you are scammed, inform the mods as soon as you can so that we may investigate and ban the offending parties if necessary.
Do not post the personal information of any Reddit users. The exception to this is if someone uses PayPal to scam a member, this information may be sent to the mods to prevent others from also being scammed. Doxxing people will not be tolerated.
Do not antagonize posters about their price, opinion, or sexual orientation (etc). This translates to be a general rule of "no dickish behavior". If you disagree with someone's price, and can post evidence that their item has a current or recent better price elsewhere such as a link to a vendor, that information is authorized to be posted. That is not antagonism. People may comment on prices and offer counter-offers, as long as behavior is not insulting or unprofessional. If you feel that someone is being unprofessional regarding pricing, report it and the mods will evaluate the case. They are the determining factor whether behavior warrants muting, temporary banning, or permanent banning based on severity of incident, past behavior, and other factors. If your behavior does not contribute towards the positive image of firearms ownership, your participation in this subreddit may not be welcome.
Soliciting any type of transaction regarding prohibited items may result in a ban. This includes Price Checks of firearms and other prohibited items, as this can be seen as an attempt to garner PM offers for prohibited items. Remember that there is no expectation of privacy from Reddit Admins, and that they have shown in the past that they have access to private message histories.
As a general guideline, if a buyer wants to use PayPal Goods and Services (G&S) rather than Friends and family (F&F), it is expected that they will absorb the ~3% fee for the increased protections. However, PayPal F&F, Zelle, and Venmo and similar payment methods are discouraged here due to a lack of protections.
All rules and guidelines are subject to change. The moderators have the final say in all issues in relation to the rules and how to enforce them.
submitted by SxbZxro to GunAccessoriesForSale [link] [comments]

Extons. IO An Easy Step-Through Crystal Financial Trade

Extons. IO An Easy Step-Through Crystal Financial Trade
Premiere
I have spoken before about Extons in my article so there's no cause to talk again about it, but I'd like to give any new visitors a quick introduction. Extons is a central platform established in 2020 that strives first and foremost to serve a wide range of crypto assets. It will help traders and companies grow quickly with its low-cost and fast transactions. This is a product of the ecosystem Thisoption.
EXTONS, what are they?
EXTONS is an exchange of cryptocurrency that supports a broad range of crypto active assets for trading. There are

https://preview.redd.it/lk8jflln97i51.jpg?width=960&format=pjpg&auto=webp&s=b460d349f9bea89fb5aac61dc617ce1898160789
five ecosystems of this option designed for traders around the world to launch. Its central crypto-monetary exchange is part of the ecosystem and technology of this Option. This supports many payment platforms that have fiat and crypto properties, and KYC wants to use this platform's software. This site was created in June 2020.
Business Framework
Security
The most important thing is the safety of a multi-model structure. A reliable business service would be offered to the consumers, with the best front end and back end services with a multilingual interface. There are many protection mechanisms used to avoid fraud and business manipulations.
An experience by strongest consumers:
The interface is quick and user-friendly. It is essential to provide the customer with the best market trading experience. Customer service is accessible online 24/7 to assist the dealer. This will ensure that all transactions are carried out smoothly.
Supports a broad variety of crypto assets:
Big cryptocurrency pairs and their trading practices are eligible for sale. This service is quite large, but it's very simple. Traders from around the globe will be able to use this platform and be part of the potential growth of this ecosystem. The big crypto assets have already been identified, so adding is one direction.
Liquidity:
Liquidity is also a crucial element that other exchanges have struggled to accomplish. Without ample liquidity, the trader would not be able to use this platform easily. Liquidity can offer more than 250 market parameters of new technologies and services.
What's Thisoption?
Thisoption is a Binary Options Trading System that is a part of the environment of this choice. It was founded in 2016 and has more than 700,000 members and continues to grow in numbers. The team is working to render this application simpler and easy to use. Investors will gain up to 80% of their investment in just 60 seconds. Users will get more than 100 trading assets that can be accessed from any device.
Is this choice perfect for trading?
This is a huge platform for traders to make a good return on investment in a short period of time. This platform provides specialized resources and apps for trades, and their support team is really helpful and supports users in any case. Every type of traders, whether pro or new, can participate on the platform, and support is there to help them learn about markets and how to trade.
https://preview.redd.it/94ybzc9n97i51.jpg?width=960&format=pjpg&auto=webp&s=751f33db79c4200d0889ae7ffbf21d42999b5f7c
The ecosystem of TONS Token
There are five components of the TONS Environment. They're-
  1. Thisoption:(Thisoption is a Binary Options Exchange)
  2. TONSPAY:(Its a payment portal in the ecosystem.)
  3. TONSTRADE:(APP TONSTRADE)
  4. EXTONS:(Cryptocurrency exchange)
  5. TONSFX:(TONSFX is a Forex exchange)
conclusion
A cryptocurrency is a huge place and one of the fastest-growing financial industries. There are over 300 active exchanges and several of them also supply the markets with ample liquidity. The EXTON.IO team is committed to delivering the finest trading experience for all its customers. They're also a lot of cool features and services for traders and willing to add more as their users want. It's a market that will help a wide variety of traders and customers around the globe. With its wide range of services, it can attract traders and investors to its ecosystem.

Website || Thisoption || Whitepaper || Telegram || Facebook || Medium

Author: u/thorex25
Disclaimer
This article is not meant to give commercial or any other kind of advice. It is just an informative text at all.
submitted by dojogang to DigitalCryptoWorld [link] [comments]

Binary Options Review; Best Binary Options Brokers

Binary Options Review; Best Binary Options Brokers

Binary Options Review; Best Binary Options Brokers
We have compared the best regulated binary options brokers and platforms in May 2020 and created this top list. Every binary options company here has been personally reviewed by us to help you find the best binary options platform for both beginners and experts. The broker comparison list below shows which binary trading sites came out on top based on different criteria.
You can put different trading signals into consideration such as using payout (maximum returns), minimum deposit, bonus offers, or if the operator is regulated or not. You can also read full reviews of each broker, helping you make the best choice. This review is to ensure traders don't lose money in their trading account.
How to Compare Brokers and Platforms
In order to trade binary options, you need to engage the services of a binary options broker that accepts clients from your country e.g. check US trade requirements if you are in the United States. Here at bitcoinbinaryoptionsreview.com, we have provided all the best comparison factors that will help you select which trading broker to open an account with. We have also looked at our most popular or frequently asked questions, and have noted that these are important factors when traders are comparing different brokers:
  1. What is the Minimum Deposit? (These range from $5 or $10 up to $250)
  2. Are they regulated or licensed, and with which regulator?
  3. Can I open a Demo Account?
  4. Is there a signals service, and is it free?
  5. Can I trade on my mobile phone and is there a mobile app?
  6. Is there a Bonus available for new trader accounts? What are the Terms and
  7. conditions?
  8. Who has the best binary trading platform? Do you need high detail charts with technical analysis indicators?
  9. Which broker has the best asset lists? Do they offer forex, cryptocurrency, commodities, indices, and stocks – and how many of each?
  10. Which broker has the largest range of expiry times (30 seconds, 60 seconds, end of the day, long term, etc?)
  11. How much is the minimum trade size or amount?
  12. What types of options are available? (Touch, Ladder, Boundary, Pairs, etc)
  13. Additional Tools – Like Early closure or Metatrader 4 (Mt4) plugin or integration
  14. Do they operate a Robot or offer automated trading software?
  15. What is Customer Service like? Do they offer telephone, email and live chat customer support – and in which countries? Do they list direct contact details?
  16. Who has the best payouts or maximum returns? Check the markets you will trade.
The Regulated Binary Brokers
Regulation and licensing is a key factor when judging the best broker. Unregulated brokers are not always scams, or untrustworthy, but it does mean a trader must do more ‘due diligence’ before trading with them. A regulated broker is the safest option.
Regulators - Leading regulatory bodies include:
  • CySec – The Cyprus Securities and Exchange Commission (Cyprus and the EU)
  • FCA – Financial Conduct Authority (UK)
  • CFTC – Commodity Futures Trading Commission (US)
  • FSB – Financial Services Board (South Africa)
  • ASIC – Australia Securities and Investment Commission
There are other regulators in addition to the above, and in some cases, brokers will be regulated by more than one organization. This is becoming more common in Europe where binary options are coming under increased scrutiny. Reputable, premier brands will have regulation of some sort.
Regulation is there to protect traders, to ensure their money is correctly held and to give them a path to take in the event of a dispute. It should therefore be an important consideration when choosing a trading partner.
Bonuses - Both sign up bonuses and demo accounts are used to attract new clients. Bonuses are often a deposit match, a one-off payment, or risk-free trade. Whatever the form of a bonus, there are terms and conditions that need to be read.
It is worth taking the time to understand those terms before signing up or clicking accept on a bonus offer. If the terms are not to your liking then the bonus loses any attraction and that broker may not be the best choice. Some bonus terms tie in your initial deposit too. It is worth reading T&Cs before agreeing to any bonus, and worth noting that many brokers will give you the option to ‘opt-out’ of taking a bonus.
Using a bonus effectively is harder than it sounds. If considering taking up one of these offers, think about whether, and how, it might affect your trading. One common issue is that turnover requirements within the terms, often cause traders to ‘over-trade’. If the bonus does not suit you, turn it down.
How to Find the Right Broker
But how do you find a good broker? Well, that’s where BitcoinBinaryOptionsReview.com comes in. We assess and evaluate binary options brokers so that traders know exactly what to expect when signing up with them. Our financial experts have more than 20 years of experience in the financial business and have reviewed dozens of brokers.
Being former traders ourselves, we know precisely what you need. That’s why we’ll do our best to provide our readers with the most accurate information. We are one of the leading websites in this area of expertise, with very detailed and thorough analyses of every broker we encounter. You will notice that each aspect of any broker’s offer has a separate article about it, which just goes to show you how seriously we approach each company. This website is your best source of information about binary options brokers and one of your best tools in determining which one of them you want as your link to the binary options market.
Why Use a Binary Options Trading Review?
So, why is all this relevant? As you may already know, it is difficult to fully control things that take place online. There are people who only pose as binary options brokers in order to scam you and disappear with your money. True, most of the brokers we encounter turn out to be legit, but why take unnecessary risks?
Just let us do our job and then check out the results before making any major decisions. All our investigations regarding brokers’ reliability can be seen if you click on our Scam Tab, so give it a go and see how we operate. More detailed scam reports than these are simply impossible to find. However, the most important part of this website can be found if you go to our Brokers Tab.
There you can find extensive analyses of numerous binary options brokers irrespective of your trading strategy. Each company is represented with an all-encompassing review and several other articles dealing with various aspects of their offer. A list containing the very best choices will appear on your screen as you enter our website whose intuitive design will allow you to access all the most important information in real-time.
We will explain minimum deposits, money withdrawals, bonuses, trading platforms, and many more topics down to the smallest detail. Rest assured, this amount of high-quality content dedicated exclusively to trading cannot be found anywhere else. Therefore, visiting us before making any important decisions regarding this type of trading is the best thing to do.
CONCLUSION: Stay ahead of the market, and recover from all kinds of binary options trading loss, including market losses in bitcoin, cryptocurrency, and forex markets too. Send your request via email to - [email protected]
submitted by Babyelijah to u/Babyelijah [link] [comments]

[Table] Asteroid Day AMA – We’re engineers and scientists working on a mission that could, one day, help save humankind from asteroid extinction. Ask us anything!

Source
There are several people answering: Paolo Martino is PM, Marco Micheli is MM, Heli Greus is HG, Detlef Koschny is DVK, and Aidan Cowley is AC.
Questions Answers
Can we really detect any asteroids in space with accuracy and do we have any real means of destroying it? Yes, we can detect new asteroids when they are still in space. Every night dozens of new asteroids are found, including a few that can come close to the Earth.
Regarding the second part of the question, the goal would be to deflect them more than destroy them, and it is technologically possible. The Hera/DART mission currently being developed by ESA and NASA will demonstrate exactly this capability.
MM
I always wanted to ask: what is worse for life on Earth - to be hit by a single coalesced asteroid chunk, or to be hit by a multiple smaller pieces of exploded asteroid, aka disrupted rubble pile scenario? DVK: This is difficult to answer. If the rubble is small (centimetres to meters) it is better to have lots of small ones – they’d create nice bright meteors. If the rubble pieces are tens of meters it doesn’t help.
Let’s say that hypothetically, an asteroid the size of Rhode Island is coming at us, it will be a direct hit - you’ve had the resources and funding you need, your plan is fully in place, everything you’ve wanted you got. The asteroid will hit in 10 years, what do you do? DVK: I had to look up how big Rhode Island is – a bit larger than the German Bundesland ‘Saarland’. Ok – this would correspond to an object about 60 km in diameter, right? That’s quite big – we would need a lot of rocket launches, this would be extremely difficult. I would pray. The good news is that we are quite convinced that we know all objects larger than just a few kilometers which come close to our planet. None of them is on a collision course, so we are safe.
the below is a reply to the above
Why are you quite convinced that you know all object of that size? And what is your approach in finding new celestial bodies? DVK: There was a scientific study done over a few years (published in Icarus 2018, search for Granvik) where they modelled how many objects there are out there. They compared this to the observations we have with the telescopic surveys. This gives us the expected numbers shown here on our infographic: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
There are additional studies to estimate the ‘completeness’ – and we think that we know everything above roughly a few km in size.
To find new objects, we use survey telescopes that scan the night sky every night. The two major ones are Catalina and Pan-STARRS, funded by NASA. ESA is developing the so-called Flyeye telescope to add to this effort https://www.esa.int/ESA_Multimedia/Images/2017/02/Flyeye_telescope.
the below is a reply to the above
Thanks for the answer, that's really interesting! It's also funny that the fist Flyeye deployed is in Sicily, at less than 100km from me, I really had no idea DVK: Indeed, that's cool. Maybe you can go and visit it one day.
the below is a reply to the original answer
What about Interstellar objects however, like Oumuamua? DVK: The two that we have seen - 'Oumuamua and comet Borisov - were much smaller than the Saarland (or Rhode Island ;-) - not sure about Borisov, but 'Oumuamua was a few hundred meters in size. So while they could indeed come as a complete surprise, they are so rare that I wouldn't worry.
Would the public be informed if an impending asteroid event were to happen? And, how would the extinction play out? Bunch of people crushed to death, knocked off our orbit, dust clouds forever? DVK: We do not keep things secret – all our info is at the web page http://neo.ssa.esa.int. The ‘risky’ objects are in the ‘risk page’. We also put info on really close approaches there. It would also be very difficult to keep things ‘under cover’ – there are many high-quality amateur astronomers out there that would notice.
In 2029 asteroid Apophis will fly really close to Earth, even closer than geostationary satellites. Can we use some of those satellites to observe the asteroid? Is it possible to launch very cheap cube sats to flyby Apophis in 2029? DVK: Yes an Apophis mission during the flyby in 2029 would be really nice. We even had a special session on that topic at the last Planetary Defense Conference in 2019, and indeed CubeSats were mentioned. This would be a nice university project – get me a close-up of the asteroid with the Earth in the background!
the below is a reply to the above
So you’re saying it was discussed and shelved? In the conference we just presented ideas. To make them happen needs funding - in the case of ESA the support of our member countries. But having something presented at a conference is the first step. One of the results of the conference was a statement to space agencies to consider embarking on such a mission. See here: https://www.cosmos.esa.int/documents/336356/336472/PDC_2019_Summary_Report_FINAL_FINAL.pdf/341b9451-0ce8-f338-5d68-714a0aada29b?t=1569333739470
Go to the section 'resolutions'. This is now a statement that scientists can use to present to their funding agencies, demonstrating that it's not just their own idea.
Thanks for doing this AMA! Did we know the Chelyabinsk meteor in 2013 (the one which had some great videos on social media) was coming? Ig not, how comes? Also, as a little side one, have there been any fatalities from impact events in the past 20 years? Unfortunately, the Chelyabinsk object was not seen in advance, because it came from the direction of the Sun where ground-based telescopes cannot look.
No known fatalities from impacts have happened in the past 20 years, although the Chelyabinsk event did cause many injuries, fortunately mostly minor.
MM
the below is a reply to the above
How often do impacts from that direction happen, compared to impacts from visible trajectories? In terms of fraction of the sky, the area that cannot be easily scanned from the ground is roughly a circle with a radius of 40°-50° around the current position of the Sun, corresponding to ~15% of the total sky. However, there is a slight enhancement of objects coming from that direction, therefore the fraction of objects that may be missed when heading towards us is a bit higher.
However, this applies only when detecting an asteroid in its "final plunge" towards the Earth. Larger asteroids can be spotted many orbits earlier, when they are farther away and visible in the night side of the sky. Their orbits can then be determined and their possible impacts predicted even years or decades in advance.
MM
There must be a trade-off when targeting asteroids as they get closer to Earth, is there a rule of thumb at what the best time is to reach them, in terms of launch time versus time to reach the asteroid and then distance from Earth? DVK: Take e.g. a ‘kinetic impactor’ mission, like what DART and Hera are testing. Since we only change the velocity of the asteroid slightly, we need to hit the object early enough so that the object has time to move away from it’s collision course. Finding out when it is possible to launch requires simulations done by our mission analysis team. They take the strength of the launcher into account, also the available fuel for course corrections, and other things. Normally each asteroid has its own best scenario.
Do you also look at protecting the moon from asteroids? Would an impact of a large enough scale potentially have major impacts on the earth? DVK: There are programmes that monitor the Moon and look for flashes from impacting small asteroids (or meteoroids) - https://neliota.astro.noa.g or the Spanish MIDAS project. We use the data to improve our knowledge about these objects. These programmes just look at what is happening now.
For now we would not do anything if we predicted a lunar impact. I guess this will change once we have a lunar base in place.
Why aren't there an international organisation comprised of countries focused on the asteroid defence? Imagine like the organisation with multi-billion $ budget and program of action on funding new telescopes, asteroid exploration mission, plans for detection of potentially dangerous NEA, protocols on action after the detection - all international, with heads of states discussing these problems? DVK: There are international entities in place, mandated by the UN: The International Asteroid Warning Network (http://www.iawn.net) and the Space Mission Planning Advisory Group (http://www.smpag.net). These groups advise the United Nations. That is exactly where we come up with plans and protocols on action. But: They don’t have budget – that needs to come from elsewhere. I am expecting that if we have a real threat, we would get the budget. Right now, we don’t have a multi-billion budget.
the below is a reply to someone else's answer
There is no actual risk of any sizable asteroids hitting earth in the foreseeable future. Any preparation for it would just be a waste of money. DVK: Indeed, as mentioned earlier, we do not expect a large object to hit is in the near future. We are mainly worried about those in the size range of 20 m to 40 m, which happen on average every few tens of years to hundreds of years. And where we only know a percent of them or even less.
President Obama wanted to send a crewed spacecraft to an asteroid - in your opinion is this something that should still be done in the future, would there be any usefulness in having a human being walk/float on an asteroid's surface? DVK: It would definitely be cool. I would maybe even volunteer to go. Our current missions to asteroids are all robotic, the main reason is that it is much cheaper (but still expensive) to get the same science. But humans will expand further into space, I am sure. If we want to test human exploration activities, doing this at an asteroid would be easier than landing on a planet.
this is another reply Yes, but I am slightly biased by the fact that I work at the European astronaut centre ;) There exist many similarities to what we currently do for EVA (extra vehicular activities) operations on the International Space Station versus how we would 'float' around an asteroid. Slightly biased again, but using such a mission to test exploration technologies would definitely still have value. Thanks Obama! - AC
I've heard that some asteroids contains large amounts of iron. Is there a possibility that we might have "space mines" in the far away future, if our own supply if iron runs out? Yes, this is a topic in the field known as space mining, part of what we call Space Resources. In fact, learning how we can process material we might find on asteroids or other planetary bodies is increasingly important, as it opens up the opportunities for sustainable exploration and commercialization. Its a technology we need to master, and asteroids can be a great target for testing how we can create space mines :) - AC
By how much is DART expected to deflect Didymos? Do we have any indication of the largest size of an asteroid we could potentially deflect? PM: Didymos is a binary asteroid, consisting of a main asteroid Didymos A (~700m) and a smaller asteroid Didymos B (~150m) orbiting around A with a ~12 hours period. DART is expected to impact Didymos B and change its orbital period w.r.t. Didymos A of ~1%. (8 mins)
The size of Didymos B is the most representative of a potential threat to Earth (the highest combination of probability and consequence of impacts), meaning smaller asteroids hit the Earth more often but have less severe consequences, larger asteroids can have catastrophic consequences but their probability of hitting the earth is very very low.
the below is a reply to the above
Why is there less probability of larger asteroids hitting earth? DVK: There are less large objects out there. The smaller they are, the more there are.
the below is a reply to the original answer
Is there any chance that your experiment will backfire and send the asteroid towards earth? PM: Not at all, or we would not do that :) Actually Dimorphos (the Didymos "moon") will not even leave its orbit around Didymos. It will just slightly change its speed.
I'm sure you've been asked this many times but how realistic is the plot of Armageddon? How likely is it that our fate as a species will rely on (either) Bruce Willis / deep sea oil drillers? Taking into consideration that Bruce Willis is now 65 and by the time HERA is launched he will be 69, I do not think that we can rely on him this time (although I liked the movie).
HERA will investigate what method we could use to deflect asteroid and maybe the results will show that we indeed need to call the deep sea oil drillers.
HG
the below is a reply to the above
So then would it be easier to train oil drillers to become astronauts, or to train astronauts to be oil drillers? I do not know which one would be easier since I have no training/experience of deep see oil drilling nor becoming an astronaut, but as long as the ones that would go to asteroid have the sufficient skills and training (even Bruce Willis), I would be happy.
HG
If budget was no object, which asteroid would you most like to send a mission to? Nice question! For me, I'd be looking at an asteroid we know something about, since I would be interested in using it for testing how we could extract resources from it. So for me, I would choose Itokawa (https://en.wikipedia.org/wiki/25143_Itokawa), which was visited by Hayabusa spacecraft. So we already have some solid prospecting carried out for this 'roid! - AC
this is another reply Not sure if it counts as an asteroid, but Detlef and myself would probably choose ʻOumuamua, the first discovered interstellar object.
MM
the below is a reply to the above
Do we even have the capability to catch up to something like that screaming through our solar system? That thing has to have a heck of a velocity to just barrel almost straight through like that. DVK: Correct, that would be a real challenge. We are preparing for a mission called 'Comet Interceptor' that is meant to fly to an interstellar object or at least a fresh comet - but it will not catch up with it, it will only perform a short flyby.
https://www.esa.int/Science_Exploration/Space_Science/ESA_s_new_mission_to_intercept_a_comet
After proving to be able to land on one, could an asteroid serve as a viable means to transport goods and or humans throughout the solar system when the orbit of said asteroid proves beneficial. While it is probably quite problematic to land the payload, it could save fuel or am I mistaken? Neat idea! Wonder if anyone has done the maths on the amount of fuel you would need/save vs certain targets. - AC
PM: To further complement, the saving is quite marginal indeed because in order to land (softly) on the asteroid you actually need to get into the very same orbit of that asteroid . At that point your orbit remains the same whether you are on the asteroid or not..
can the current anti-ballistic missiles systems intercept a terminal phase earth strike asteroid? or it is better to know beforehand and launch an impacting vehicle into space? DVK: While I do see presentations on nuclear explosions to deflect asteroids at our professional meetings, I have not seen anybody yet studying how we could use existing missile systems. So it's hard to judge whether existing missiles would do the job. But in general, it is better to know as early as possible about a possible impact and deflect it as early as possible. This will minimize the needed effort.
How much are we prepared against asteroid impacts at this moment? DVK: 42… :-) Seriously – I am not sure how to quantify ‘preparedness’. We have international working groups in place, mentioned earlier (search for IAWN, SMPAG). We have a Planetary Defence Office at ESA, a Planetary Defense Office at NASA (who spots the difference?), search the sky for asteroids, build space missions… Still we could be doing more. More telescopes to find the object, a space-based telescope to discover those that come from the direction of the Sun. Different test missions would be useful, … So there is always more we could do.
Have you got any data on the NEO coverage? Is there estimations on the percentage of NEOs we have detected and are tracking? How can we improve the coverage? How many times have asteroids been able to enter earths atmosphere without being detected beforehand? Here’s our recently updated infographics with the fraction of undiscovered NEOs for each size range: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
As expected, we are now nearly complete for the large ones, while many of the smaller ones are still unknown.
In order to improve coverage, we need both to continue the current approach, centered on ground-based telescopes, and probably also launch dedicated telescopes to space, to look at the fraction of the sky that cannot be easily observed from the ground (e.g., towards the Sun).
Regarding the last part of your question, small asteroids enter the Earth atmosphere very often (the infographics above gives you some numbers), while larger ones are much rarer.
In the recent past, the largest one to enter our atmosphere was about 20 meters in diameter, and it caused the Chelyabinsk event in 2013. It could not be detected in advance because it came from the direction of the Sun.
We have however detected a few small ones before impact. The first happened in 2008, when a ~4-meter asteroid was found to be on a collision course less than a day before impact, it was predicted to fall in Northern Sudan, and then actually observed falling precisely where (and when) expected.
MM
this is another reply >After
DVK: And to add what MM said - Check out http://neo.ssa.esa.int. There is a ‘discovery statistics’ section which provides some of the info you asked about. NASA is providing similar information here https://cneos.jpl.nasa.gov/stats/. To see the sky which is currently covered by the survey telescopes, you need to service of the Minor Planet Center which we all work together with: http://www.minorplanetcenter.org, ‘observers’, ‘sky coverage’. That is a tool we use to plan where we look with our telescopes, so it is a more technical page.
Are there any automatic systems for checking large numbers of asteroids orbits, to see if the asteroid's orbit is coming dangerously close to Earth, or is it done by people individually for every asteroid? I ask it because LSST Rubin is coming online soon and you know it will discover a lot of new asteroids. Yes, such systems exist, and monitor all known and newly discovered asteroids in order to predict possible future impacts.
The end result of the process is what we call "risk list": http://neo.ssa.esa.int/risk-page
It is automatically updated every day once new observational data is processed.
MM
What are your favourite sci-fi series? DVK: My favorites are ‘The Expanse’, I also liked watching ‘Salvation’. For the first one I even got my family to give me a new subscription to a known internet streaming service so that I can see the latest episodes. I also loved ‘The Jetsons’ and ‘The Flintstones’ as a kid. Not sure the last one counts as sci-fi though. My long-time favorite was ‘Dark Star’.
this is another reply Big fan of The Expanse at the moment. Nice, hard sci-fi that has a good impression of being grounded in reality - AC
this is another reply When I was a kid I liked The Jetsons, when growing up Star Trek, Star wars and I also used to watch with my sister the 'V'.
HG
When determining the potential threat of a NEA, is the mass of an object a bigger factor or size? I'm asking because I'm curious if a small but massive object (say, with the density of Psyche) could survive atmospheric entry better than a comparatively larger but less massive object. The mass is indeed what really matters, since it’s directly related with the impact energy.
And as you said composition also matters, a metal object would survive atmospheric entry better, not just because it’s heavier, but also because of its internal strength.
MM
What are your thoughts on asteroid mining as portrayed in sci-fi movies? Is it feasible? If so would governments or private space programs be the first to do so?What type of minerals can be found on asteroids that would merit the costs of extraction? Certainly there is valuable stuff you can find on asteroids. For example, the likely easiest material you can harvest from an asteroid would be volatiles such as H2O. Then you have industrial metals, things like Iron, Nickel, and Platinum group metals. Going further, you can break apart many of the oxide minerals you would find to get oxygen (getting you closer to producing rocket fuel in-situ!). Its feasible, but still needs alot of testing both here on Earth and eventually needs to be tested on a target. It may be that governments, via agencies like ESA or NASA, may do it first, to prove the principles somewhat, but I know many commercial entities are also aggresively working towards space mining. To show you that its definitely possible, I'd like to plug the work of colleagues who have processed lunar regolith (which is similar to what you may find on asteroids) to extract both oxygen and metals. Check it out here: http://www.esa.int/ESA_Multimedia/Images/2019/10/Oxygen_and_metal_from_lunar_regolith
AC
Will 2020's climax be a really big rock? DVK: Let's hope not...
Considering NASA, ESA, IAU etc. is working hard to track Earth-grazing asteroids, how come the Chelyabinsk object that airburst over Russia in 2013 came as a total surprise? The Chelyabinsk object came from the direction of the Sun, where unfortunately ground-based telescopes cannot look at. Therefore, it would not have been possible to discover it in advance with current telescopes. Dedicated space telescopes are needed to detect objects coming from this direction in advance.
MM
the below is a reply to the above
Is this to say that it was within specific solid angles for the entire time that we could have observed it given its size and speed? Yes, precisely that. We got unlucky in this case.
MM
Have any of you read Lucifer's Hammer by Larry Niven? In your opinion, how realistic is his depiction of an asteroid strike on Earth? DVK: I have – but really long ago, so I don’t remember the details. But I do remember that I really liked the book, and I remember I always wanted to have a Hot Fudge Sundae when reading it.
I was thinking about the asteroid threat as a teen and came up with this ideas (Hint: they are not equally serious, the level of craziness goes up real quick). Could you please comment on their feasibility? 1. Attaching a rocket engine to an asteroid to make it gradually change trajectory, do that long in advance and it will miss Earth by thousands of km 2. Transporting acid onto asteroid (which are mainly metal), attaching a dome-shaped reaction chamber to it, using heat and pressure to then carry out the chemical reaction to disintegrate asteroids 3. This one is even more terrible than a previous one and totally Dan Brown inspired — transporting antimatter on asteroid, impacting and causing annihilation. Thank you for this AMA and your time! DVK: Well the first one is not so crazy, I have seen it presented... the difficulty is that all asteroids are rotating in one way or another. So if you continuously fire the engine it would not really help. You'd need to switch the engine on and off. Very complex. And landing on an asteroid is challenging too. Just using the 'kinetic impactor' which we will test with DART/Hera (described elsewhere in this chat) is simpler. Another seriously proposed concept is to put a spacecraft next to an asteroid and use an ion engine (like we have on our Mercury mission BepiColombo) to 'push' the asteroid away.
As for 2 and 3 I think I will not live to see that happening ;-)
What is the process to determine the orbit of a newly discovered asteroid? The process is mathematically quite complex, but here's a short summary.
Everything starts with observations, in particular with measurements of the position of an asteroid in the sky, what we call "astrometry". Discovery telescopes extract this information from their discovery images, and make it available to everybody.
These datapoints are then used to calculate possible trajectories ("orbits") that pass through them. At first, with very few points, many orbits will be possible.
Using these orbits we can extrapolate where the asteroid will be located during the following nights, use a telescope to observe that part of the sky, and locate the object again.
From these new observations we can extract new "astrometry", add it to the orbit determination, and see that now only some of the possible orbits will be compatible with the new data. As a result, we now know the trajectory better than before, because a few of the possible orbits are not confirmed by the new data.
The cycle can then continue, with new predictions, new observations, and a more accurate determination of the object's orbit, until it can be determined with an extremely high level of accuracy.
MM
What are some asteroids that are on your "watchlist"? We have exactly that list on our web portal: http://neo.ssa.esa.int/risk-page
It's called "risk list", and it includes all known asteroids for which we cannot exclude a possible impact over the next century. It is updated every day to include newly discovered asteroids, and remove those that have been excluded as possible impactors thanks to new observations.
MM
the below is a reply to the above
That's quite a list!! Do you guys ever feel stressed or afraid when you have to add another dangerous candidate (and by dangerous I mean those above 200m) is added to this Risk List? Yes, when new dangerous ones are added it's important that we immediately do our best to gather more data on them, observing them with telescopes in order to get the information we need to improve our knowledge of their orbit.
And then the satisfaction of getting the data needed to remove one from the list is even greater!
MM
What inspired you to go into this field of study? I was fascinated by astronomy in general since I was a kid, but the actual "trigger" that sparked my interest in NEOs was a wonderful summer course on asteroids organized by a local amateur astronomers association. I immediately decided that I would do my best to turn this passion into my job, and I'm so happy to have been able to make that dream come true.
MM
this is another reply DVK: I started observing meteors when I was 14, just by going outside and looking at the night sky. Since then, small bodies in the solar system were always my passion.
As a layperson, I still think using nuclear weapons against asteroids is the coolest method despite better methods generally being available. Do you still consider the nuclear option the cool option, or has your expertise in the field combined with the real-life impracticalities made it into a laughable/silly/cliche option? DVK: We indeed still study the nuclear option. There are legal aspects though, the ‘outer space treaty’ forbids nuclear explosions in space. But for a large object or one we discover very late it could be useful. That’s why we have to focus on discovering all the objects out there as early as possible – then we have time enough to use more conventional deflection methods, like the kinetic impactor (the DART/Hera scenario).
It seems like doing this well would require international cooperation, particularly with Russia. Have you ever reached out to Russia in your work? Do you have a counterpart organization there that has a similar mission? DVK: Indeed international cooperation is important - asteroids don't know about our borders! We work with a Russian team to perform follow-up observations of recently discovered NEOs. Russia is also involved in the UN-endorsed working groups that we have, IAWN and SMPAG (explained in another answer).
how much can experts tell from a video of a fireball or meteor? Can you work out what it's made of and where it came from? https://www.reddit.com/space/comments/hdf3xe/footage_of_a_meteor_at_barrow_island_australia/?utm_source=share&utm_medium=web2x If multiple videos or pictures, taken from different locations, are available, then it's possible to reconstruct the trajectory, and extrapolate where the object came from.
Regarding the composition, it's a bit more difficult if nothing survives to the ground, but some information can be obtained indirectly from the fireball's color, or its fragmentation behavior. If a spectral analysis of the light can be made, it's then possible to infer the chemical composition in much greater detail.
MM
I've always wanted to know what the best meteorite buying site is and what their average price is?? DVK: Serious dealers will be registered with the 'International Meteorite Collectors Association (IMCA)' - https://www.imca.cc/. They should provide a 'certificate of authenticity' where it says that they are member there. If you are in doubt, you can contact the association and check. Normally there are rough prices for different meteorite types per gram. Rare meteorites will of course be much more expensive than more common ones. Check the IMCA web page to find a dealer close to you.
Just read through Aidans link to the basaltic rock being used as a printing material for lunar habitation. There is a company called Roxul that does stone woven insulation that may be able to shed some light on the research they have done to minimize their similarity to asbestos as potentially carcinogenic materials deemed safe for use in commercial and residential applications. As the interior surfaces will essentially be 3D printed lunar regolith what are the current plans to coat or dampen the affinity for the structure to essentially be death traps for respiratory illness? At least initially, many of these 3d printed regolith structures would not be facing into pressurised sections, but would rather be elements placed outside and around our pressure vessels. Such structures would be things like radiation shields, landing pads or roadways, etc. In the future, if we move towards forming hermetically sealed structures, then your point is a good one. Looking into terrestrial solutions to this problem would be a great start! - AC
What kind of career path does it take to work in the asteroid hunting field? It's probably different for each of us, but here's a short summary of my own path.
I became interested in asteroids, and near-Earth objects in particular, thanks to a wonderful summer course organized by a local amateur astronomers association. Amateur astronomers play a great role in introducing people, and young kids in particular, to these topics.
Then I took physics as my undergrad degree (in Italy), followed by a Ph.D. in astronomy in the US (Hawaii in particular, a great place for astronomers thanks to the exceptional telescopes hosted there).
After finishing the Ph.D. I started my current job at ESA's NEO Coordination Centre, which allowed me to realize my dream of working in this field.
MM
this is another reply DVK: Almost all of us have a Master's degree either in aerospace engineering, mathematics, physics/astronomy/planetary science, or computer science. Some of us - as MM - have a Ph.D. too. But that's not really a requirement. This is true for our team at ESA, but also for other teams in other countries.
What is the likelihood of an asteroid hitting the Earth In the next 200 years? It depends on the size, large ones are rare, while small ones are much more common. You can check this infographics to get the numbers for each size class: https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_danger_explained
MM
Have you played the Earth Defence Force games and if you have, which one is your favourite? No I have not played the Earth Defence Force games, but I just looked it up and I think I would liked it. Which one would you recommend?
HG
How close is too close to earth? Space is a SUPER vast void so is 1,000,000 miles close, 10,000,000? And if an asteroid is big enough can it throw earth off its orbit? DVK: Too close for my taste is when we compute an impact probability > 0 for the object. That means the flyby distance is zero :-) Those are the objects on our risk page http://neo.ssa.esa.int/risk-page.
If an object can alter the orbit of another one, we would call it planet. So unless we have a rogue planet coming from another solar system (verrry unlikely) we are safe from that.
How can I join you when I'm older? DVK: Somebody was asking about our career paths... Study aerospace engineering or math or physics or computer science, get a Masters. Possibly a Ph.D. Then apply for my position when I retire. Check here for how to apply at ESA: https://www.esa.int/About_Us/Careers_at_ESA/Frequently_asked_questions2#HR1
How much is too much? DVK: 42 again
Are you aware of any asteroids that are theoretically within our reach, or will be within our reach at some point, that are carrying a large quantity of shungite? If you're not aware, shungite is like a 2 billion year old like, rock stone that protects against frequencies and unwanted frequencies that may be traveling in the air. I bought a whole bunch of the stuff. Put them around the la casa. Little pyramids, stuff like that. DVK: If I remember my geology properly, Shungite forms in water sedimental deposits. This requires liquid water, i.e. a larger planet. So I don't think there is a high chance to see that on asteroids.
submitted by 500scnds to tabled [link] [comments]

1-minute (“60-second”) Binary Options Strategy - YouTube 60 Seconds binary options strategy 99 - 100% Winning (100% ... Day Trading 60 Second Binary Options Using Martingale Trading Strategy 60 Second Binary Options Trading Strategy - EUR/USD Rapid ... Binary Options 60 Seconds Indicator 99% Winning Live ... 60 Second Binary Options 10 Minute Trend Trading Strategy ... 60 Second Binary Options Strategy Wins 90% of The Time ... How to Trade Binary Options Ep. 1 - 60 Second Binary ...

60-second binary options are for traders that want to be very active in the market and see results fast. Since these options expire in one minute you can potentially do hundreds of trades a day. Like traditional binary options, if you believe an asset will be higher than the current price 60 seconds from now you’ll buy a call option. If believe an asset will be lower than the current price ... Best 60 Seconds Binary Options Brokers of 2015. As the cheeta is the fastest animal on land, the 60 second binary option is (now) the second fastest trade online. There are now 30 second rocket options you can trade if you need even more action. There are few experiences more thrilling than trading 60-second binary options. These are literally ... More 60 second binary options trading strategies articles; Good Day Traders, I’m Kostasze and my first article is about my trading style and some comments in my trades. First of all, I want to say that I am a short- term binary options trader, 1 min and 5 min expiry are both short-term trading.Personally, I prefer trading 1 min expiry with 1min chart.I sometimes use 5min chart to filter some ... 60 seconds binary options strategy system for trading online forex and binary options system with major profits for all traders. English Arabic Chinese (Simplified) Danish Dutch English Filipino French German Hindi Indonesian Italian Japanese Korean Malay Myanmar (Burmese) Norwegian Persian Polish Portuguese Romanian Russian Spanish Swedish Thai Turkish Vietnamese A Simple But Effective 60-Second Binary Options Strategy In the past we have often made reference to trading our 60-second options contracts in sets of three, which we refer to as a “series”. We have found this to be a simple but effective 60-second binary options strategy. This simple strategy can help you to become […] This means that 60 second binary option trading is best suited for numerous trend trading strategies. Trends with strong momentum are likely to remain that way in the really short term. Drawbacks of 60 Second trading. Although one can make a lot of money in the short term with 60 second options, they can also lose a lot of money. Binary Options ... Laden Sie die Extreme 60 Second Binary Options-Strategie herunter. Benötigen Sie einen Übungsplatz, bevor Sie echtes Geld einsetzen. ZigZag-Strategie - Eine 60-Sekunden-Strategie für die Nacht. Die Website wurde für den Benutzer erstellt, und das erste, was auffällt, wenn Sie auf der Website landen, ist das Popup-Fenster für den Kundendienst-Chat, in dem Sie gefragt werden, ob Sie Hilfe ...

[index] [28086] [3155] [1546] [22413] [4307] [14499] [23113] [4326] [17154] [18643]

1-minute (“60-second”) Binary Options Strategy - YouTube

Rapid Fire is an exciting binary options trading strategy utilising the 60 second expiry rates. This video explains how to use candlestick analysis to determ... Learn how to trade 60 seconds binary options with Price Action - BO301 - Duration: 22:01. InvestingOnline 28,998 views. 22:01. Make a Living in 1 Hour a Day Trading the 3 Bar Play!! Download this template here: http://barbarianarrow.com In this tutorial I teach how to win 90% of the time with 60 second strategy for binary options. This i... 1-minute (“60-second”) Binary Options Strategy Download App... https://app.appsflyer.com/com.iqoptio... https://affiliate.iqoption.com/redir/... 60 Seconds binary options strategy 99 - 100% Winning (100% profit guaranteed) 90 - 95% Winning Binary Options Strategy in case of correct prediction - 1 to 5... USA Friendly Broker: http://porterfinancecapital.com EU Broker: http://bosscapitaloptions.com CandlestickTrend Charts: http://www.fxempire.com/charts/live-fo... Free Demo Account: http://www.FreeBinaryDemoForever.com Full Curriculum Here: http://www.FTSBinaryCurriculum.com The first 7 minutes is intro/educational whi... Hi Friends I will Show This Video Binary Options 60 Seconds Indicator Signal 99% Winning Live Trading Proof -----...

https://binary-optiontrade.faeknutcilygpole.tk