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Comment: Re: Umm no (Score 1) 442

by leonardluen (#48032363) Attached to: The Physics of Space Battles

oops, i guess i missed this part "but the complete weapon, with feed system and drum, weighs 4,029 pounds (1,828 kg)"

so the platform would might have to be up to 5k to 6k kg, which is around the size of a geostationary communication satellite.
but would then allow us to fire off 7k to 9k rounds before we stop the platform. the GAU-8 fires at 3900rpm, so this is only a 2 to 3 second burst.

Comment: Re: Umm no (Score 1) 442

by leonardluen (#48032317) Attached to: The Physics of Space Battles

the GAU-8 fires a 0.69 kg round at a muzzle velocity of 990 m/s, the gun itself weighs 280kg we will use that as a starting point. according to a random website a "medium sized satellite" would be around 1000kg so lets use that for an estimate to the size of our entire thing to include electronics and such. so if my math is right each round fired would add about 0.683m/s of backwards velocity to the platform. say the platform was traveling towards the target at around 1000 m/s in the begining then you could fire off around 1500 rounds before the platform comes to a dead stop relative to the target. and the first rounds you fired would be traveling nearly 2k m/s towards the target.

Clearly the only way to resolve this argument would be for the USAF to let us borrow an A10 and fire the gun! not entirely sure what it would prove, but it would be fun.


Comment: Re: Umm no (Score 1) 442

by leonardluen (#48026537) Attached to: The Physics of Space Battles

what is your point? if you have gyros to control orientation and aim you probably have computers and some sensors to aim. the gun platform is now much closer to the target than the original ship from where you had launched it, so it should also be much easier to hit the target now. the target will also have less time to react to the projectile and move out of the way now.

but to fire projectiles at a moving target you have to fire ahead of it so the projectiles and the target meet.

this is already a solved problem. we already do it on earth with patriot missile system. and some of the targets they take down are moving faster than they do.

the amount of thrust used to fire the projectiles that way will push your gun and whatever it's mounted to, backward with the exact same force. you mean just like you see in the movies where the guy shooting the gun gets thrown across the room, just like the guy he shot at?

the gun platform will already have velocity towards the target. all it is doing is getting in closer to the intended target, correcting the aim, and then shooting a projectile smaller than itself. (bonus points if the platform itself also hits the target, but this isn't needed). yes there will be some kickback when you fire, but it doesn't necessarily matter since you don't care if the platform itself hits. you already have velocity towards the target any more you can add to the projectile is a bonus. in addition you could either add extra mass to the platform to help counteract this kick, or add rockets to it that fire off just before you fire the projectile so that you can impart the most velocity possible into the projectile towards the target.

and actually it might be good to calculate the charge so that once the projectile is fired, it takes all forward momentum away from the gun platform relative to the target and parks it right in front of the enemy, just being a nuisance in their way. though you would probably want to fry the electronics so they can't easily reload it and send it back.

Comment: Re: Umm no (Score 1) 442

by leonardluen (#48021539) Attached to: The Physics of Space Battles

i would imagine the "missile" would contain gyroscopes so it can change orientation without using thrusters. For bonus points you could even make it look like a natural meteoroid, then when it gets close to its target it, it uses the gyroscopes to aim towards the target and can fire off a bunch of smaller projectiles designed to pierce the target's hull.

the radiation from thrusters is what is most likely to give you away, so this eliminates them entirely.

The Almighty Buck

Miss a Payment? Your Car Stops Running 903

Posted by timothy
from the welcome-to-the-future dept. writes Auto loans to borrowers considered subprime, those with credit scores at or below 640, have spiked in the last five years with roughly 25 percent of all new auto loans made last year subprime, a volume of $145 billion in the first three months of this year. Now the NYT reports that before they can drive off the lot, many subprime borrowers must have their car outfitted with a so-called starter interrupt device, which allows lenders to remotely disable the ignition. By simply clicking a mouse or tapping a smartphone, lenders retain the ultimate control. Borrowers must stay current with their payments, or lose access to their vehicle and a leading device maker, PassTime of Littleton, Colo., says its technology has reduced late payments to roughly 7 percent from nearly 29 percent. "The devices are reshaping the dynamics of auto lending by making timely payments as vital to driving a car as gasoline."

Mary Bolender, who lives in Las Vegas, needed to get her daughter to an emergency room, but her 2005 Chrysler van would not start. Bolender was three days behind on her monthly car payment. Her lender remotely activated a device in her car's dashboard that prevented her car from starting. Before she could get back on the road, she had to pay more than $389, money she did not have that morning in March. "I felt absolutely helpless," said Bolender, a single mother who stopped working to care for her daughter. Some borrowers say their cars were disabled when they were only a few days behind on their payments, leaving them stranded in dangerous neighborhoods. Others said their cars were shut down while idling at stoplights. Some described how they could not take their children to school or to doctor's appointments. One woman in Nevada said her car was shut down while she was driving on the freeway. Attorney Robert Swearingen says there's an old common law principle that a lender can't "breach the peace" in a repossession. That means they can't put a person in harm's way. To Swearingen, that would mean "turning off a car in a bad neighborhood, or for a single female at night."

Comment: Re:In Theory (Score 1) 387

by leonardluen (#47880897) Attached to: Unpopular Programming Languages That Are Still Lucrative

I don't know.

many Access project start like yours but then the business outgrows it, but then by the time you realize that you are then stuck with Access and have nowhere to go as it is doing all of your business logic and has turned into a monster.

  we originally moved everything to PHP and MYSQL, but have since converted most things to Java and MSSQL, with a little bit of C# here or there.

Our path probably isn't too helpful to you. i work for a university primarily developing internal applications. The majority of our decisions on what platforms to use are made based on what our slave labor (students workers) are capable of doing, so this is probably not necessarily what would work best for most businesses. The students may be cheap but they have extremely high turnover, as we can't keep them after they graduate. To be fair we do pay them and this is one of the highest paid student jobs available on campus. we have a short time to train them and get them productive before they leave, we have to work around their class schedules during the school year so we only get them part time, and considering they are still taking their CS classes they often know little to nothing when we get them. considering those limitations, i think we do quite well and the students that work for us get some valuable work experience that has helped them start their career after graduation.

Comment: Re:In Theory (Score 1) 387

by leonardluen (#47862427) Attached to: Unpopular Programming Languages That Are Still Lucrative

I used to do Foxpro, it at least paid for my education. i would still pick it over MS Access on most days. we long ago converted everything out of foxpro and had never allowed anything that uses Access.

my favorite little side project that i had worked on in my free time was a sort of foxpro VM written in foxpro...yeah everyone thought i was crazy.

Comment: Re:Crichton is an idiot. (Score 1) 770

by leonardluen (#47854531) Attached to: How Scientific Consensus Has Gotten a Bad Reputation

the point i am trying to make is that it takes more than one scientist to be "right". science is about repeatability. it takes multiple scientists repeating an experiment to advance our knowledge. if no one can repeat it, then that original scientist must have been wrong. When you have multiple scientist repeat an experiment and come to the same conclusion isn't that a consensus?

also there are any number of reasons that others may not be willing or able to repeat an experiment. if the subject matter is too controversial or had major hoaxes which dried up funding, such as maybe cold fusion for example, then even if someone does find something it is possible no one would be willing to verify those experiments as they may either view it as a waste of time or just bad for their reputation to be associated with looking into something that is so controversial and everyone "KNOWS" is wrong. it took a long time for the stigma around cold fusion to die down enough that scientists would begin looking at it again without fear of it being a black mark on their careers. now i am not saying i believe in cold fusion, just that it is an example where controversy can stop other scientists from conducting research into that subject.

Comment: Re:Crichton is an idiot. (Score 1) 770

by leonardluen (#47852959) Attached to: How Scientific Consensus Has Gotten a Bad Reputation

science is about repeatability. if only one investigator happens to be right, and no one else can repeat his experiment, then there will be no consensus even if he happens to be right. the prevailing hypothesis has stood the test of time and had multiple scientists repeat experiments to verify it, this is how the consensus forms.

Without a consensus most scientists will ignore it and go off to research something else, but then once in a while someone may come along and say "i wonder if this really is true?" and then they will run an experiment to try to confirm it. They will then either confirm it which reinforces the consensus, or will say hey these results don't fit, something is wrong here. they must then get other scientists on their side to repeat the experiment to confirm the results. if no one is interested in running those experiments then it doesn't really matter how right that scientist is, his discovery that the accepted hypothesis is wrong will be forgotten. and so consensus is very important to science

Comment: Re:First step to SkyNet (Score 2) 108

1) history shows that humans absolutely destroy anything that ever threatens us.

2) robots don't need oxygen to breath.

instead of trying to kill humans it is most likely that robots will just leave the earth. humans won't easily be able to chase them so then the robots can live on their own and mine some asteroid or moon for resources and not have to compete with humans.

Comment: Re:150 kelvin = -189.67 F (Score 1) 39

if you are converting miles to 16ths of an inch you are doing something wrong.

really there isn't much need most of the time to convert between miles and inches or even feet and miles. the only real reason for that is to compress the number when you write it down. there is nothing stopping you from using deca-feet or kilo-feet.

typically when you are working in miles you aren't measuring down to the foot. so you would say something is 3.5 miles not 3 miles and 2640 feet or 3 miles and 880 yards.

the imperial system is designed around construction. using either feet or yards as our base unit for construction we can easily divide it into many different factors using inches. want something to be 1/3rd of a foot? easy that is 4 inches. now try doing that with metric.

really the imperial system (for distance) has multiple different measurement scales it just so happens that we designed them so we can easily scale between them. metric only has one. the meter with multiple prefixes we can attach to it. i will grant you that metric is far better for most scientific measurements. and when you get to relativistic speeds and stellar distances the imperial units mean nothing to me, i need to see it in metric to get a proper sense of scale.

now i am not by any means against metric, i just don't loath the imperial system.

however at relativistic speeds and stellar distances your precious metric system sort of breaks down. how many kilometers in a light year? you can use a calculator, and good luck. :P

*well i guess light year isn't really a metric unit but it is a commonly used scientific unit of measure, and does not easily convert to meters.

Everyone can be taught to sculpt: Michelangelo would have had to be taught how not to. So it is with the great programmers.