The engine can throttle between 50% and 100%. It is true that even 50% of just one of the nine engines is enough to shoot the rocket back towards space. Which is why it can not hover.
But hover is not relevant. Hitting zero velocity at height zero is.
Let the rocket drop freely while continuously calculating needed thrust to hit the target velocity zero at zero height. Keep dropping until your algorithm says you need 75% thrust. At this moment you relight your engine at 75%.
Now you can do a control loop with feedback to vary the throttle between 50% and 100% with the perfect descent hitting 75%. This should be plenty to do the job.
In addition you have at least two other mechanism to help a successful landing. One is the braking by aerodynamic mechanisms that can be varied. Those might be more precise than engine throttling. Another is the landing legs. They will be designed to absorb hitting the ground at a small non zero velocity.
There is no lose or win - is this the kindergarten?
I replied to one claim and one claim only: that the PC to server ratio is in excess of a million to one. That claim is so absurd that anyone not laughing their ass off is an idiot that has trouble with big numbers.
FACT: The PC to Server ratio is MILLIONS to 1 alone
This does not stand to even 5 ms of thinking. I am living in a country with 5 million people. You are claiming we have 5 servers or something like that.
Or if you are an american: How many cities do you have with more than 5 million people? How many cities with more than 5 servers?...
Or... there are about 7 billion people on the earth. Lets assume that each have a PC (many don't). You are claiming there are only 7000 servers on earth.
Here we have a very effective law that put a complete stop to the non-compete bullshit: any company that wants a non-compete contract will have to pay half salary for the entire period where said non-compete contract is valid.
So if you stop working somewhere, they have to keep paying you half salary, if they really think that non-compete contract is necessary. They almost never do.
Linux has been able do multipath routing for a long time: it means being able to have routes with multiple gateways and to use them in a (weighted) round-robin fashion. But Linux is missing a tool to actively monitor the state of internet uplinks and change the routing accordingly
No the author is lacking knowledge of such tools. There are at least three major implementations of common routing protocols for Linux.
It is actually surprisingly simple. You activate OSPF on your Linux box and it will add routes on working links and remove them again if the path is no longer viable. Works both ways too, so your routers will not try to deliver traffic to your box on a dead link. Instead the routers will route around the problem.
The car clearly lacks enough sensors to become truly self driving. How is it going to avoid changing lane in front of a faster moving car, when it has no rear facing sensor with longer range than 12 ft? How is it going to tell the difference between a pole and a child on a bicycle before doing a right turn, when it only has simple sonar sensors in that direction?
They could at the very least have added more cameras. Cameras are cheap. Why not let the computer have 360 degree view of what is happening around the car?
But it might also be that there is no way around using LIDAR. It is expensive like hell, but that might change when you need millions of devices a year.
In any case, the new Tesla does not have the hardware necessary to implement the vision of a self driving car. They know it, so that is why they call it "auto pilot" instead. It is just sad that it is nothing new. Every other car in that segment already has this "auto pilot" under different names.
Said kill switch could just limit engine power, tell the driver to stop safely before bringing engine power down to zero in steps. Basically what happens if you run out of fuel (charge). People usually do not get hurt from that.
But if you are completely without power, say the RAT has failed or you had a fire that destroyed the wiring, then you will crash. There is no way for a human to control those beasts by muscle power alone, even for those planes that are not fly by wire.
The worse thing that could happen to a view screen is that it gets so smashed up you can't resolve fine details through all the cracks (actually, the absolutely worse thing that could happen is that it ceases to exist, but at that point you've got other problems). But the fine details are hardly necessary for flying and landing.
As Flight 9 approached Jakarta, the crew found it difficult to see anything through the windscreen, and made the approach almost entirely on instruments, despite reports of good visibility. The crew decided to fly the Instrument Landing System (ILS); however, the vertical guidance system was inoperative, so they were forced to fly with only the lateral guidance as the first officer monitored the airport's Distance Measuring Equipment (DME). He then called out how high they should be at each DME step along the final approach to the runway, creating a virtual glide slope for them to follow. It was, in Moody's words, "a bit like negotiating one's way up a badger's arse."[1] Although the runway lights could be made out through a small strip of the windscreen, the landing lights on the aircraft seemed to be inoperable. After landing, the flight crew found it impossible to taxi, due to glare from apron floodlights which made the already sandblasted windscreen opaque.
As you see, they didn't eject. They landed the plane flying blind.
The main reason that Falcon 9 Heavy is delayed is said to be that they are sold out on stages. They can't produce them fast enough to spare some to test the heavy.
This SLS will not bring 130 ton to LEO. They are just working on the small version, that will not do much more than Falcon 9 Heavy (53 tons vs 70 tons for SLS).
The SLS project will be cancelled long before they manage to test the 130 ton version.
SpaceX already has Falcon 9 Heavy which will do most of what NASA wants to do with SLS. In addition SpaceX is developing the Mars Colonial Transporter http://en.wikipedia.org/wiki/M... which will put 100 tons of cargo on Mars. In comparison the SLS will only put 100 tons in low earth orbit.
Oh and the Mars Colonial Transporter will be reusable.
You like C#, I like Scala and the next guy over likes Haskell. Trying to force everyone to use one language that fits all is one of the big fails of JavaScript.
Language development is an ongoing research area. You can not just freeze time and say we will use this one for the rest of time.
This is why we now have a host of languages that compiles to JavaScript. I use Scala-JS that will convert my Scala to JavaScript. But this is horrible inefficient and limiting.
Portable Native Client is a LLVM based byte code language, that is designed to be a target for other programming languages. You can compile your beloved C# to PNaCl, someone can compile his C++ and I can compile my Scala. And it is almost as fast as if you used machine code as target.
That and the fact that you have people who forget to remove the nozzle before leaving the gas station. How many of these people will a supercharging station fry?
None. An electric car will not move while still plugged in.
in gp example it would be:::::::1.2.3.4 or::::::1:2:3:4 or perhaps netname::1.2.3.4 there's tons of better ways then having to memorize 8 groupings of 4 letters.
The last one is already legal syntax:
baldur@ballerup1:~$ ping6 -c3 2a03:7900:64::8.8.8.8 PING 2a03:7900:64::8.8.8.8(2a03:7900:64::808:808) 56 data bytes 64 bytes from 2a03:7900:64::808:808: icmp_seq=1 ttl=43 time=28.7 ms 64 bytes from 2a03:7900:64::808:808: icmp_seq=2 ttl=43 time=29.0 ms 64 bytes from 2a03:7900:64::808:808: icmp_seq=3 ttl=43 time=29.7 ms
--- 2a03:7900:64::8.8.8.8 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2002ms rtt min/avg/max/mdev = 28.737/29.158/29.730/0.419 ms
An actual example of an IPV6 address is as follows:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
That is not an actual example of an IPv6 address. Lets try with some real examples instead:
google.com has IPv6 address 2a00:1450:4005:801::1007 gmail.com has IPv6 address 2a00:1450:400f:803::1016 facebook.com has IPv6 address 2a03:2880:2110:df07:face:b00c::1 arin.net has IPv6 address 2001:500:4:13::124 arin.net has IPv6 address 2001:500:4:13::125 ripe.net has IPv6 address 2001:67c:2e8:22::c100:68b gigabit.dk has IPv6 address 2a00:7660:0:50::2
The last one is my own website. Your IPv6 address is as long as you want it to be. Many ISPs will assign you a/48 prefix, which is just 16 bits more than your IPv4. It is literally just an area code more (two bytes). What happens with the last 80 bits is up to you. You can make them all zero if you want to. And since all zero can be shortened to "::" that all just goes away.
As to those first 48 bits there is a system in it, which makes it easier to remember. Notice how all of the above has either 2001 or 2a0x as the first block? Also the second block is the ISP and most people only deal with a few of those. So you will quickly memorize that. The third block is basically your customer id within the ISP. And everything after that is yours to decide.
It is true that if you go with auto configuration addresses on your computer, you will get horrible long addresses. But if you are doing that, you are not the kind of person to deal with IP addresses. Personally I let my computer choose any long address it want, but for my servers I am picking something sane.
The space shuttle was $450 million per mission not including development costs. That would lift 24 ton and a lot of volume to ISS. That was good for building the space station but perhaps overkill for the maintenance. They are not even using the full capability of the Dragon spacecraft.
The Dragon will only move 3.3 ton to the ISS. If you only count weight by dollar this is more expensive than a Space Shuttle launch. On the other hand you will get much more frequent deliveries which may be what is needed now.
If you count development costs, each Space Shuttle launch was 1.5 billion USD. Viewed this way, the CRS program for Space X is just one shuttle. And perhaps this is the correct way to do the accounting considering that the 1.6 billion that Space X receives also has to cover their development costs. I would expect that they can give a good discount on future launches, should NASA want more than 12.
Because it is unlikely to be true. Anyone can go to the Tesla website and check the prices. You will get the car at the price listed on the site, no more and no less.
If he is talking about financing, nothing forces you to finance the car through Tesla. In my part of the world one usually borrows the money in a bank and this is how it is done when buying from a dealer too.
Slashdot Mirror
The engine can throttle between 50% and 100%. It is true that even 50% of just one of the nine engines is enough to shoot the rocket back towards space. Which is why it can not hover.
But hover is not relevant. Hitting zero velocity at height zero is.
Let the rocket drop freely while continuously calculating needed thrust to hit the target velocity zero at zero height. Keep dropping until your algorithm says you need 75% thrust. At this moment you relight your engine at 75%.
Now you can do a control loop with feedback to vary the throttle between 50% and 100% with the perfect descent hitting 75%. This should be plenty to do the job.
In addition you have at least two other mechanism to help a successful landing. One is the braking by aerodynamic mechanisms that can be varied. Those might be more precise than engine throttling. Another is the landing legs. They will be designed to absorb hitting the ground at a small non zero velocity.
There is no lose or win - is this the kindergarten?
I replied to one claim and one claim only: that the PC to server ratio is in excess of a million to one. That claim is so absurd that anyone not laughing their ass off is an idiot that has trouble with big numbers.
You want me to prove there are 7 billion people on earth?! You are more stupid than a kid in first grade.
FACT: The PC to Server ratio is MILLIONS to 1 alone
This does not stand to even 5 ms of thinking. I am living in a country with 5 million people. You are claiming we have 5 servers or something like that.
Or if you are an american: How many cities do you have with more than 5 million people? How many cities with more than 5 servers? ...
Or ... there are about 7 billion people on the earth. Lets assume that each have a PC (many don't). You are claiming there are only 7000 servers on earth.
Here we have a very effective law that put a complete stop to the non-compete bullshit: any company that wants a non-compete contract will have to pay half salary for the entire period where said non-compete contract is valid.
So if you stop working somewhere, they have to keep paying you half salary, if they really think that non-compete contract is necessary. They almost never do.
Linux has been able do multipath routing for a long time: it means being able to have routes with multiple gateways and to use them in a (weighted) round-robin fashion. But Linux is missing a tool to actively monitor the state of internet uplinks and change the routing accordingly
No the author is lacking knowledge of such tools. There are at least three major implementations of common routing protocols for Linux.
It is actually surprisingly simple. You activate OSPF on your Linux box and it will add routes on working links and remove them again if the path is no longer viable. Works both ways too, so your routers will not try to deliver traffic to your box on a dead link. Instead the routers will route around the problem.
The car clearly lacks enough sensors to become truly self driving. How is it going to avoid changing lane in front of a faster moving car, when it has no rear facing sensor with longer range than 12 ft? How is it going to tell the difference between a pole and a child on a bicycle before doing a right turn, when it only has simple sonar sensors in that direction?
They could at the very least have added more cameras. Cameras are cheap. Why not let the computer have 360 degree view of what is happening around the car?
But it might also be that there is no way around using LIDAR. It is expensive like hell, but that might change when you need millions of devices a year.
In any case, the new Tesla does not have the hardware necessary to implement the vision of a self driving car. They know it, so that is why they call it "auto pilot" instead. It is just sad that it is nothing new. Every other car in that segment already has this "auto pilot" under different names.
What good is https going to be against the state? You think they can not coerce Verisign et al to hand over a copy of the root keys?
There was a passenger in the Tesla. He didn't get thrown out and walked away from the accident. Unburned.
Said kill switch could just limit engine power, tell the driver to stop safely before bringing engine power down to zero in steps. Basically what happens if you run out of fuel (charge). People usually do not get hurt from that.
Nobody knows what strongly typed means: http://en.wikipedia.org/wiki/S...
But if you are completely without power, say the RAT has failed or you had a fire that destroyed the wiring, then you will crash. There is no way for a human to control those beasts by muscle power alone, even for those planes that are not fly by wire.
The worse thing that could happen to a view screen is that it gets so smashed up you can't resolve fine details through all the cracks (actually, the absolutely worse thing that could happen is that it ceases to exist, but at that point you've got other problems). But the fine details are hardly necessary for flying and landing.
Not so, This 747 went through a ash cloud from a vulcano and got their windscreen sandblasted: http://en.wikipedia.org/wiki/B...
As Flight 9 approached Jakarta, the crew found it difficult to see anything through the windscreen, and made the approach almost entirely on instruments, despite reports of good visibility. The crew decided to fly the Instrument Landing System (ILS); however, the vertical guidance system was inoperative, so they were forced to fly with only the lateral guidance as the first officer monitored the airport's Distance Measuring Equipment (DME). He then called out how high they should be at each DME step along the final approach to the runway, creating a virtual glide slope for them to follow. It was, in Moody's words, "a bit like negotiating one's way up a badger's arse."[1] Although the runway lights could be made out through a small strip of the windscreen, the landing lights on the aircraft seemed to be inoperable. After landing, the flight crew found it impossible to taxi, due to glare from apron floodlights which made the already sandblasted windscreen opaque.
As you see, they didn't eject. They landed the plane flying blind.
Next year is much sooner than SLS.
The main reason that Falcon 9 Heavy is delayed is said to be that they are sold out on stages. They can't produce them fast enough to spare some to test the heavy.
This SLS will not bring 130 ton to LEO. They are just working on the small version, that will not do much more than Falcon 9 Heavy (53 tons vs 70 tons for SLS).
The SLS project will be cancelled long before they manage to test the 130 ton version.
SpaceX already has Falcon 9 Heavy which will do most of what NASA wants to do with SLS. In addition SpaceX is developing the Mars Colonial Transporter http://en.wikipedia.org/wiki/M... which will put 100 tons of cargo on Mars. In comparison the SLS will only put 100 tons in low earth orbit.
Oh and the Mars Colonial Transporter will be reusable.
You like C#, I like Scala and the next guy over likes Haskell. Trying to force everyone to use one language that fits all is one of the big fails of JavaScript.
Language development is an ongoing research area. You can not just freeze time and say we will use this one for the rest of time.
This is why we now have a host of languages that compiles to JavaScript. I use Scala-JS that will convert my Scala to JavaScript. But this is horrible inefficient and limiting.
The correct solution is PNaCl: http://en.wikipedia.org/wiki/G...
Portable Native Client is a LLVM based byte code language, that is designed to be a target for other programming languages. You can compile your beloved C# to PNaCl, someone can compile his C++ and I can compile my Scala. And it is almost as fast as if you used machine code as target.
That and the fact that you have people who forget to remove the nozzle before leaving the gas station. How many of these people will a supercharging station fry?
None. An electric car will not move while still plugged in.
in gp example it would be: ::::::1.2.3.4 or ::::::1:2:3:4 or perhaps netname::1.2.3.4
there's tons of better ways then having to memorize 8 groupings of 4 letters.
The last one is already legal syntax:
baldur@ballerup1:~$ ping6 -c3 2a03:7900:64::8.8.8.8
PING 2a03:7900:64::8.8.8.8(2a03:7900:64::808:808) 56 data bytes
64 bytes from 2a03:7900:64::808:808: icmp_seq=1 ttl=43 time=28.7 ms
64 bytes from 2a03:7900:64::808:808: icmp_seq=2 ttl=43 time=29.0 ms
64 bytes from 2a03:7900:64::808:808: icmp_seq=3 ttl=43 time=29.7 ms
--- 2a03:7900:64::8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 28.737/29.158/29.730/0.419 ms
Nothing stops you from assigning fe80::1 to your printer #1 and so forth. Or you can use ULA to the same effect: fd00::1 to the first printer etc.
Or do it the sane way and use your prefix::1.
You do not have to use MAC based addresses you know. You can just assign the addresses manually (static) or you can use a DHCPv6 server.
You do realize that a 32 bit computer will easily do 64 bit math?
An actual example of an IPV6 address is as follows:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
That is not an actual example of an IPv6 address. Lets try with some real examples instead:
google.com has IPv6 address 2a00:1450:4005:801::1007
gmail.com has IPv6 address 2a00:1450:400f:803::1016
facebook.com has IPv6 address 2a03:2880:2110:df07:face:b00c::1
arin.net has IPv6 address 2001:500:4:13::124
arin.net has IPv6 address 2001:500:4:13::125
ripe.net has IPv6 address 2001:67c:2e8:22::c100:68b
gigabit.dk has IPv6 address 2a00:7660:0:50::2
The last one is my own website. Your IPv6 address is as long as you want it to be. Many ISPs will assign you a /48 prefix, which is just 16 bits more than your IPv4. It is literally just an area code more (two bytes). What happens with the last 80 bits is up to you. You can make them all zero if you want to. And since all zero can be shortened to "::" that all just goes away.
As to those first 48 bits there is a system in it, which makes it easier to remember. Notice how all of the above has either 2001 or 2a0x as the first block? Also the second block is the ISP and most people only deal with a few of those. So you will quickly memorize that. The third block is basically your customer id within the ISP. And everything after that is yours to decide.
It is true that if you go with auto configuration addresses on your computer, you will get horrible long addresses. But if you are doing that, you are not the kind of person to deal with IP addresses. Personally I let my computer choose any long address it want, but for my servers I am picking something sane.
The space shuttle was $450 million per mission not including development costs. That would lift 24 ton and a lot of volume to ISS. That was good for building the space station but perhaps overkill for the maintenance. They are not even using the full capability of the Dragon spacecraft.
The Dragon will only move 3.3 ton to the ISS. If you only count weight by dollar this is more expensive than a Space Shuttle launch. On the other hand you will get much more frequent deliveries which may be what is needed now.
If you count development costs, each Space Shuttle launch was 1.5 billion USD. Viewed this way, the CRS program for Space X is just one shuttle. And perhaps this is the correct way to do the accounting considering that the 1.6 billion that Space X receives also has to cover their development costs. I would expect that they can give a good discount on future launches, should NASA want more than 12.
More likely we would all be using some variant of BSD instead. But still, Linux is far greater than GIT. The list of alternatives to GIT is long.
Because it is unlikely to be true. Anyone can go to the Tesla website and check the prices. You will get the car at the price listed on the site, no more and no less.
If he is talking about financing, nothing forces you to finance the car through Tesla. In my part of the world one usually borrows the money in a bank and this is how it is done when buying from a dealer too.