20kw is nowhere near three times the efficiency of an average charger.
Home chargers for Tesla offer 20kw (22kw in EU) for usual setup.
Superchargers offer a lot more - 135kw for Tesla superchargers, 50kw for regular EU charging stations.
Re:TFA has no clue about orbital mechanics
on
How To Die On Mars
·
· Score: 1
F=G(M1*M2/r^2)
a = F / m therefore a =G (m1 * m2 / r ^ 2) / m1 therefore a =G (m2 / r ^ 2)
and v1 = v0 + a * t therefore there is no relation between v1 and m1
QFT
TFA has no clue about orbital mechanics
on
How To Die On Mars
·
· Score: 4, Informative
Heavy objects will pick up too much speed during the descent, making for one deep impact.
1. Speed gained during decent does not depend on weight of the craft. When considering aero-braking/parachuting/gliding the only thing that matters is lift/drag generating surface area vs mass
2. Speed gained during decent (from mars gravity) is nominal compared to orbital transfer speed/orbital speed that needs to be zeroed.
Mars orbital speed at 200km is around 2.4km/s, total amount of speed gained from direct decent from 200km to 0km on Mars is around 1.2km/s (with no atmosphere), in real life we would see orbital speed (2.4km's) decreasing on decent due to atmospheric drag (until it reaches terminal velocity, which depends on point 1. but should be less than 1km/s for any viable design).
Prior to achieving stable orbit around mars we have to (aero-)brake from at least 15km/s (orbital transfer). So theoretical 1.2km/s from Mars gravity (which actually doesn't happen) is a really small amount of additional velocity compared to the amount we have to brake anyway.
Playing a few hours of KSP should be mandatory prior to posting articles about space flight on the internet:)
Qi has been around for quite some time. My last 3 phones have supported it and i love it
If i want to use OpenDots I have to buy a new phone (none on market atm), a few new charging plates (none on market atm) and a car that supports it (a few on market)?
OpenDots is not as safe (try spilling your drink on the pad:)) and is not supported by a single phone at the moment, while Qi has ~50 phones with built in support on sale at the moment and hundreds more that accommodate Qi via accessories (i.e. Qi enabled cover)
Qi is not open-source but its free for low wattage devices (phones) and at reasonable cost for higher wattage devices (all patents are RAND)
What is the advantage for consumer to use OpenDots vs Qi? What is the advantage for manufacturer to use OpenDots vs Qi (considering existing Qi infrastructure)
Most of the advises given (if not all) are ineffective and in some cases make things worse.
Code and data obfuscation only provides false sense of security (and a large paycheck for your "security" vendor) - If i have access to binaries, have root OS access and skills to de-compile the app, obfuscation/encryption (with local key) is only a small nuisance (compared to skill required for decompilation/repackaging/on-the-fly modification)
Moving data to server-side provides a simpler attack-vector - i can MTM the (hopefully) secure connection and alter data sent to app - i don't even have to decompile the app to hack it
On-the-fly binary validation does not work (again, if i have OS level access) - i can disable/fake it.
The numbers in the paper are classic marketing bull - when are you more likely to buy an 99$ in-app purchase? - if you can do it for free (Apple MTM bug) - if you actually have to pay for it
TLDR: You can't protect against hacking/repackaging if the hacker has access to binaries and root. You can't protect against data modification if the hacker can install hes own CA on the device.
Considering that the daily trading volume of popular exchanges is around 50k BTC / 27m$ at the moment, and that he dumps all coins directly to market, he might lower the price by 0.5% (8/(50*31))!
Doge coin rig, built in December for 850$ has earned 4800$ so far and another ~1200$ is expected before it turns obsolete (cost of power passes turnover). It has paid itself in DOLLARS many times over.
Bigger rigs, like in TFA have a bit longer lifetime and higher profit margins (assuming you use top-of-the line off-the-shelf components and won't start inventing the wheel yourself)
Unfortunately space elevator would have to extend quite far above GEO in order to be stable. It's center of mass would have to be on GEO orbit (or a little below it) for the elevator to be stable.
This is probably the reason why rail-gun type launch systems have attracted more research in last few years.
Using the elevator for transfer of goods - will work but the goods will get a huge dose of radiation
Using it for transfer of organic matter (i.e. humans) above LEO is not feasible due to the speed/shielding needed
The worst part of Van Allen belt is about 19000km wide and starts at around 7000km high. Apollo moon missions passed trough it at roughly 15km/s, spending roughly 2*21 minutes in it. The astronauts received roughly 1rem of radiation through 3 layers of thick aluminum radiation shielding. That is 1/5 of the yearly the limit in US for people working with radiation. At reasonable speed (~200m/s) the elevator would take ~26h to pass through the belt, meaning it would need at least 75x more radiation shielding than Apollo did and that the lift would need 15m thick aluminum honeycomb walls (using 70's technology).
Even with todays technology the shielding will be way too bulky/heavy for elevators to be viable alternative to rockets for above LEO human transfer.
Machinima lives of these kind of promotions (all Machinima affiliates get multiple offers per month)
The total cost for this promotion for Machinima is 3750$ (promotion ends when this CPM target is met)
It is likely Microsoft entered into a deal with Machinima to increase it's visibility and Machinima did the promotion on it's own (like it has done with a lot of brands before)
The point of the article wasn't to crack it, it was to show that if something sounds insecure by design, it is insecure...
DropBox allows you to "log in" to it's website via click in the application -> no credentials required. Therefore it must either store user credentials or some other secret(s) on client side (host_id and host_int in this case).
Any process running under privileges accessible to you can be cracked (albeit sand-boxing, in which case you need system privileges) and it can't hide data from end-user / other processes in same privilege space (albeit sand-boxing....). They can make it more difficult though (extracting Bluray key from windows media player will take anyone at least a few days)
More and more big companies think they can hide data on client side and be secure. Dropbox, Windows Live (LiveConnect) and numerous others are now relying on fast exchange of nonces in addition to client-side secret storing to make it secure "enough".. But breaking the nonce handshake and authenticating in programmatic fashion will add maybe 10% more cracking/programming effort on top of the regular cracking effort.
TLDR: If it is insecure by design, it is insecure and no amount of obfuscation will help you....
You run the executable...
You ask kernel to stop executing it...
You dump the memory...
Voila - you have the unencrypted executable...
This process, including writing the tools for it, will take a person who knows what hes doing around 5 minutes... (if the program is large, it might take longer due to disk write speeds)...
Yes, they can obfuscate the assembly, but it still will be the assembly - perfectly human readable.
It might be pain to reverse engineer the whole program, but it can be done. But in most cases I've seen the hacker doesn't want to reverse engineer the whole program, he just wants to alter it a little / extract some crucial information from it (i.e. private keys). Obfuscation doesn't make this harder at all - You find some interesting OS level calls (i.e. socket creation - you cant obfuscate that...) and using debugger/stack traces/assembly/hooks you poke around a bit to find the part that is interesting to you...
From security point of view, assembly encryption (no matter how good it is) is comparable to covering your house with packing paper to prevent thieves from entering...
We have few hundred employees and 2 actual physical fixed-line phones (at reception)
But we do have "fixed line numbers" for pretty much everyone
All is done over VOIP with intelligent back-end, when someone calls me on my fixed number (or some call is redirected to me):
* If I'm behind my laptop, company IM rings in laptop with options to redirect/hold/answer via headset/answer via mobile/etc.
* If I'm away from my laptop (IM status auto changes after 5 min of inactivity), my phone and laptop ring at the same time (laptop silently), so i can answer it from my phone or do whatever from laptop
* If my Outlook/IM status is "DND" or my workday is over then i get a e-mail notification and the call is redirected to reception / help-desk (depending on caller)
Having and actual physical phone on my desk would mean that i miss 70% of calls (i have to move around the office quite a lot) and it would take up valuable desk space (where would i put my Chuck Norris motivational picture then:))
This makes sense.. really...
If I'm a true fan, I have liked the page and am liking a lot of updates from the page... therefore FB sees that I am interested in the content provided by the page and i get 100% of hes updates
If i have liked the page by accident (or just don't really care about what it has to say), then i don't "like" the updates of the page and soon enough i will stop getting them... (except for really popular ones)
So if I'm not getting the updates, i DON'T CARE about them and its perfectly fair for FB to charge him for spamming my news-feed.
I understand that he has invested in advertising but hes got the return from that... a lot of users who liked the page and got temporary exposure to he brand.. expecting this to go on forever is like expecting that if you publish a TV ad, then every person who has seen one of your ad's is committed to see all your other adds (multiple a day) for the rest of eternity....
Also he forgets to mention that by doing a sponsored post, he will get exposure to users who have not yet liked hes page...
Lets build a petrol power plant, direct its exhausts to this new CO2 -> petrol power plant and feed the created petrol back in the petrol power plant...
If we are efficient enough, we might have discovered a way to burn petrol without any pollution or energy created
In some cases, data-URI might be still faster (though less bw-effective), i.e if you take the original example and account for 54ms latency (3way handshake+initial response packet) then reloading the page (with all images cached) would take 0,054*20=1,08s since a query to the server for each image is still required
When using high-latency - high-throughput connection (i.e. mobile, satellite) then data-URI will be a lot faster than caching.
Take a website with 100 small images, with average image size 10kb, latency (3-way handshake+data) = 25ms, and your bandwidth = 10Mbit/s
Using 5 paralel connections (max allowed by http) the site will download in 10/1280*100 + 0,025*20 = 1,28 seconds
Embeding all images in original document using data URI's (~1.37x overhead to data size but no latency impact), the site will download in 10*100*1,37/1280 = 1,07 seconds
HTTP2.0 / SPDY will solve this, but it will take many years till they are widely adopted.
If there were protests in California (with 1 policeman and 8 rioters dead) and Russia would send tens of thousands of troops and tanks to California, to which US responded by attacking invading Russians... would that be considered an unprovoked attack on "international peace-keepers" as well?
All war activities (including bombing) started after Russian invasion in Georgia, what country in its right state of mind wouldn't defend itself?
South Ossetia is still under Russian military occupation...
I live in EU and i fly to Egypt twice a year to update my drug supply (in addition to a nice vacation).
I have chronic migraine (serious pain every 3-5 days, I've seen all the best doctors nearby and no one can help me)
There is one drug that can take the pain away in ~2 hours... the problem... it costs 80$ (after subsidies) a pill thanks to patents. On average i need 2 pills per seizure (my worst has been 4 pills). Buying the medications from EU will mean around 15k / year
In Egypt they sell a generic version of the same drug, only they don't pay patent fees... it costs 2$ for a box of 20 pills.
So going to Egypt twice a year and bringing back the maximum legal amount of the medicine costs me around 1k / year and i get 2 weeks of vacation as a bonus
So yes, I would buy it on-line if i could, but it's illegal thanks to the same companies who are making 8000%+ margin on the pills...
Patents are OK as long as you actually invent and market/license something. If you take some exiting idea, patent it and expect other companies to pay you for it... then you must be living in the US...
This is virtually the same thing as laptop docs... not to mention existing mobile docs (Motorla Lapdock) Anyone claiming license fees or royalties from this "invention" is actually hindering innovation and it's widespread adoption
If you live off ad-revenue, then neither Android or iOS is going to feed you. One of our iOS apps manged to fall to 0.006 eCPM while pubCenter (WP7) has 0.4 - 1.3 eCPM for the same app
Slashdot Mirror
20kw is nowhere near three times the efficiency of an average charger.
Home chargers for Tesla offer 20kw (22kw in EU) for usual setup.
Superchargers offer a lot more - 135kw for Tesla superchargers, 50kw for regular EU charging stations.
F=G(M1*M2/r^2)
a = F / m therefore
a =G (m1 * m2 / r ^ 2) / m1 therefore
a =G (m2 / r ^ 2)
and v1 = v0 + a * t therefore there is no relation between v1 and m1
QFT
Heavy objects will pick up too much speed during the descent, making for one deep impact.
1. Speed gained during decent does not depend on weight of the craft.
:)
When considering aero-braking/parachuting/gliding the only thing that matters is lift/drag generating surface area vs mass
2. Speed gained during decent (from mars gravity) is nominal compared to orbital transfer speed/orbital speed that needs to be zeroed.
Mars orbital speed at 200km is around 2.4km/s, total amount of speed gained from direct decent from 200km to 0km on Mars is around 1.2km/s (with no atmosphere), in real life we would see orbital speed (2.4km's) decreasing on decent due to atmospheric drag (until it reaches terminal velocity, which depends on point 1. but should be less than 1km/s for any viable design).
Prior to achieving stable orbit around mars we have to (aero-)brake from at least 15km/s (orbital transfer). So theoretical 1.2km/s from Mars gravity (which actually doesn't happen) is a really small amount of additional velocity compared to the amount we have to brake anyway.
Playing a few hours of KSP should be mandatory prior to posting articles about space flight on the internet
Qi has been around for quite some time. My last 3 phones have supported it and i love it
:)) and is not supported by a single phone at the moment, while Qi has ~50 phones with built in support on sale at the moment and hundreds more that accommodate Qi via accessories (i.e. Qi enabled cover)
If i want to use OpenDots I have to buy a new phone (none on market atm), a few new charging plates (none on market atm) and a car that supports it (a few on market)?
OpenDots is not as safe (try spilling your drink on the pad
Qi is not open-source but its free for low wattage devices (phones) and at reasonable cost for higher wattage devices (all patents are RAND)
What is the advantage for consumer to use OpenDots vs Qi?
What is the advantage for manufacturer to use OpenDots vs Qi (considering existing Qi infrastructure)
Most of the advises given (if not all) are ineffective and in some cases make things worse.
Code and data obfuscation only provides false sense of security (and a large paycheck for your "security" vendor) - If i have access to binaries, have root OS access and skills to de-compile the app, obfuscation/encryption (with local key) is only a small nuisance (compared to skill required for decompilation/repackaging/on-the-fly modification)
Moving data to server-side provides a simpler attack-vector - i can MTM the (hopefully) secure connection and alter data sent to app - i don't even have to decompile the app to hack it
On-the-fly binary validation does not work (again, if i have OS level access) - i can disable/fake it.
The numbers in the paper are classic marketing bull - when are you more likely to buy an 99$ in-app purchase?
- if you can do it for free (Apple MTM bug)
- if you actually have to pay for it
TLDR:
You can't protect against hacking/repackaging if the hacker has access to binaries and root.
You can't protect against data modification if the hacker can install hes own CA on the device.
Considering that the daily trading volume of popular exchanges is around 50k BTC / 27m$ at the moment, and that he dumps all coins directly to market, he might lower the price by 0.5% (8/(50*31))!
Doge coin rig, built in December for 850$ has earned 4800$ so far and another ~1200$ is expected before it turns obsolete (cost of power passes turnover). It has paid itself in DOLLARS many times over.
Bigger rigs, like in TFA have a bit longer lifetime and higher profit margins (assuming you use top-of-the line off-the-shelf components and won't start inventing the wheel yourself)
Unfortunately space elevator would have to extend quite far above GEO in order to be stable. It's center of mass would have to be on GEO orbit (or a little below it) for the elevator to be stable.
This is probably the reason why rail-gun type launch systems have attracted more research in last few years.
Using the elevator for transfer of goods - will work but the goods will get a huge dose of radiation
Using it for transfer of organic matter (i.e. humans) above LEO is not feasible due to the speed/shielding needed
The worst part of Van Allen belt is about 19000km wide and starts at around 7000km high. Apollo moon missions passed trough it at roughly 15km/s, spending roughly 2*21 minutes in it.
The astronauts received roughly 1rem of radiation through 3 layers of thick aluminum radiation shielding.
That is 1/5 of the yearly the limit in US for people working with radiation.
At reasonable speed (~200m/s) the elevator would take ~26h to pass through the belt, meaning it would need at least 75x more radiation shielding than Apollo did and that the lift would need 15m thick aluminum honeycomb walls (using 70's technology).
Even with todays technology the shielding will be way too bulky/heavy for elevators to be viable alternative to rockets for above LEO human transfer.
Full contract at http://pastebin.com/vec6vjv5/
Machinima lives of these kind of promotions (all Machinima affiliates get multiple offers per month)
The total cost for this promotion for Machinima is 3750$ (promotion ends when this CPM target is met)
It is likely Microsoft entered into a deal with Machinima to increase it's visibility and Machinima did the promotion on it's own (like it has done with a lot of brands before)
The point of the article wasn't to crack it, it was to show that if something sounds insecure by design, it is insecure...
DropBox allows you to "log in" to it's website via click in the application -> no credentials required. Therefore it must either store user credentials or some other secret(s) on client side (host_id and host_int in this case).
Any process running under privileges accessible to you can be cracked (albeit sand-boxing, in which case you need system privileges) and it can't hide data from end-user / other processes in same privilege space (albeit sand-boxing....).
They can make it more difficult though (extracting Bluray key from windows media player will take anyone at least a few days)
More and more big companies think they can hide data on client side and be secure. Dropbox, Windows Live (LiveConnect) and numerous others are now relying on fast exchange of nonces in addition to client-side secret storing to make it secure "enough".. But breaking the nonce handshake and authenticating in programmatic fashion will add maybe 10% more cracking/programming effort on top of the regular cracking effort.
TLDR: If it is insecure by design, it is insecure and no amount of obfuscation will help you....
You run the executable...
You ask kernel to stop executing it...
You dump the memory...
Voila - you have the unencrypted executable...
This process, including writing the tools for it, will take a person who knows what hes doing around 5 minutes... (if the program is large, it might take longer due to disk write speeds)...
Yes, they can obfuscate the assembly, but it still will be the assembly - perfectly human readable.
It might be pain to reverse engineer the whole program, but it can be done. But in most cases I've seen the hacker doesn't want to reverse engineer the whole program, he just wants to alter it a little / extract some crucial information from it (i.e. private keys). Obfuscation doesn't make this harder at all - You find some interesting OS level calls (i.e. socket creation - you cant obfuscate that...) and using debugger/stack traces/assembly/hooks you poke around a bit to find the part that is interesting to you...
From security point of view, assembly encryption (no matter how good it is) is comparable to covering your house with packing paper to prevent thieves from entering...
Estonia here
35 euro for 150/10 (146/10 on speedtest.net) uncapped, including cable (basic, 70 channels) and landline
40 euro for 100/50 4G LTE (91/44 on speedtest.net) uncapped, including unlimited calls and texts
3 euro for 5/1 3G (5/1 on speedtest.net), uncapped, no calls/texts included
We have few hundred employees and 2 actual physical fixed-line phones (at reception)
:))
But we do have "fixed line numbers" for pretty much everyone
All is done over VOIP with intelligent back-end,
when someone calls me on my fixed number (or some call is redirected to me):
* If I'm behind my laptop, company IM rings in laptop with options to redirect/hold/answer via headset/answer via mobile/etc.
* If I'm away from my laptop (IM status auto changes after 5 min of inactivity), my phone and laptop ring at the same time (laptop silently), so i can answer it from my phone or do whatever from laptop
* If my Outlook/IM status is "DND" or my workday is over then i get a e-mail notification and the call is redirected to reception / help-desk (depending on caller)
Having and actual physical phone on my desk would mean that i miss 70% of calls (i have to move around the office quite a lot) and it would take up valuable desk space (where would i put my Chuck Norris motivational picture then
Had it for a bit under a week, so far no glitches and I'm really loving it!
ATM cells in your DSL line have ~10% overhead
each TCP/IP packet has ~2.5% overhead in best case
TCP/IP handhakes(and resets) might add another 2-3%
So 20% overhead in data transfered vs useful data is actually realistic over DSL line
This makes sense.. really...
If I'm a true fan, I have liked the page and am liking a lot of updates from the page... therefore FB sees that I am interested in the content provided by the page and i get 100% of hes updates
If i have liked the page by accident (or just don't really care about what it has to say), then i don't "like" the updates of the page and soon enough i will stop getting them... (except for really popular ones)
So if I'm not getting the updates, i DON'T CARE about them and its perfectly fair for FB to charge him for spamming my news-feed.
I understand that he has invested in advertising but hes got the return from that... a lot of users who liked the page and got temporary exposure to he brand.. expecting this to go on forever is like expecting that if you publish a TV ad, then every person who has seen one of your ad's is committed to see all your other adds (multiple a day) for the rest of eternity....
Also he forgets to mention that by doing a sponsored post, he will get exposure to users who have not yet liked hes page...
Lets build a petrol power plant, direct its exhausts to this new CO2 -> petrol power plant and feed the created petrol back in the petrol power plant...
If we are efficient enough, we might have discovered a way to burn petrol without any pollution or energy created
In some cases, data-URI might be still faster (though less bw-effective), i.e if you take the original example and account for 54ms latency (3way handshake+initial response packet) then reloading the page (with all images cached) would take 0,054*20=1,08s since a query to the server for each image is still required
When using high-latency - high-throughput connection (i.e. mobile, satellite) then data-URI will be a lot faster than caching.
Take a website with 100 small images, with average image size 10kb, latency (3-way handshake+data) = 25ms, and your bandwidth = 10Mbit/s
Using 5 paralel connections (max allowed by http) the site will download in 10/1280*100 + 0,025*20 = 1,28 seconds
Embeding all images in original document using data URI's (~1.37x overhead to data size but no latency impact), the site will download in 10*100*1,37/1280 = 1,07 seconds
HTTP2.0 / SPDY will solve this, but it will take many years till they are widely adopted.
http://xkcd.com/1085//
Most of time noone cares what you have to say
When someone cares they will have the means to listen in
http://xkcd.com/538//
It doesn't include Stockholm (Sweden) for example, thanks to public infrastructure basic TV+phone+100/100 subscription costs 14$
I live in Tallinn (Estonia) and i get cable (~100 channels) + phone (unlimited) + 250/50 net for ~35$
If there were protests in California (with 1 policeman and 8 rioters dead) and Russia would send tens of thousands of troops and tanks to California, to which US responded by attacking invading Russians... would that be considered an unprovoked attack on "international peace-keepers" as well?
All war activities (including bombing) started after Russian invasion in Georgia, what country in its right state of mind wouldn't defend itself?
South Ossetia is still under Russian military occupation...
I live in EU and i fly to Egypt twice a year to update my drug supply (in addition to a nice vacation).
I have chronic migraine (serious pain every 3-5 days, I've seen all the best doctors nearby and no one can help me)
There is one drug that can take the pain away in ~2 hours... the problem... it costs 80$ (after subsidies) a pill thanks to patents.
On average i need 2 pills per seizure (my worst has been 4 pills).
Buying the medications from EU will mean around 15k / year
In Egypt they sell a generic version of the same drug, only they don't pay patent fees... it costs 2$ for a box of 20 pills.
So going to Egypt twice a year and bringing back the maximum legal amount of the medicine costs me around 1k / year and i get 2 weeks of vacation as a bonus
So yes, I would buy it on-line if i could, but it's illegal thanks to the same companies who are making 8000%+ margin on the pills...
Patents are OK as long as you actually invent and market/license something.
If you take some exiting idea, patent it and expect other companies to pay you for it... then you must be living in the US...
This is virtually the same thing as laptop docs... not to mention existing mobile docs (Motorla Lapdock)
Anyone claiming license fees or royalties from this "invention" is actually hindering innovation and it's widespread adoption
If you live off ad-revenue, then neither Android or iOS is going to feed you. One of our iOS apps manged to fall to 0.006 eCPM while pubCenter (WP7) has 0.4 - 1.3 eCPM for the same app