Become a fan of Slashdot on Facebook


Forgot your password?

Comment: No wireless, use multiple laptops (Score 1) 384

by Brianwa (#49741355) Attached to: Ask Slashdot: Best Way To Solve a Unique Networking Issue?

Many people on here are suggesting the use of wifi to avoid having wires going everywhere. Don't do that. Many embedded devices don't do sanity checking on their firmware images. A dropped packet could silently corrupt the firmware, or cause the process to stall for no apparent reason, or some other headache that you don't want to deal with.

In any case, these devices are on isolated machine networks and it's probably best to keep it that way. You should really just get multiple laptops. Once you get a rhythm going it's easy to babysit 3 or 4 laptops. You'll crank through the job pretty quickly and the constant motion from one to the next will keep boredom at bay for much longer than just staring at a progress bar.

Comment: Re:Depends on what you mean by "problems" (Score 1) 307

Yeah we had some UPS's with line filters but they only helped a bit. Ironically it was the higher quality power supplies that were the worst, at the time there were changing regulations about power factor correction and all the new-style PFC circuits were the first to explode.

I think it was a fairly unique situation, there was some weird student designed high power laser stuff on the same circuit. If you put an oscilloscope across mains, you could see visible distortion. No filter is going to do much about that.

Comment: Re:Depends on what you mean by "problems" (Score 1) 307

In terms of sheer number of failures, PSUs take the cake. Hell, I once ran a computer lab that shared a circuit with some nasty lab equipment, each computer would burn through 4-6 PSUs per year. They tend to be easy to troubleshoot and quick to replace though.

I still think hard drives have caused the greatest number of problems for me. If someone comes to me with a dropped laptop it's almost an automatic 6+ hours of work trying to recover any data from it (because of course they don't have backups). If a server blows a RAID controller there's going to be downtime. It could be seconds or it could be days but it's going to happen.

Plus Windows 7 and 8 get all weird and crashy whenever there's a flaky storage device anywhere in the system. I've spent way too much time trying to troubleshoot what appeared to be software problems and turned out to be a bad hard drive.

I've had good luck with fans. I've only replaced a handful and only because they were loud and annoying, never completely failed.

Comment: Re:Who would have thought (Score 1) 194

by Brianwa (#47887175) Attached to: The Documents From Google's First DMV Test In Nevada
I do it all the time, certain parts of America have roundabouts that are impossible to navigate without stopping to back up multiple times in a vehicle that's slightly above average length. If you have to go left it's safer and easier (and, oddly enough, often legal) to just go left.

We also have roundabouts with stop signs at some of the entrances, "roundabouts" that are legally regular intersections where oncoming traffic does NOT yield, and roundabouts shaped such that people going one direction can cruise through at very high speeds and others can't see far enough to know if they should yield or not until it's too late.

Comment: Re:Help! Help! (Score 1) 865

by Brianwa (#46925911) Attached to: Did the Ignition Key Just Die?

I don't think ABS will work in most cars when the engine is turned off. In my car, if you turn the engine off and then move the switch back to "on" without starting it, the ABS light comes on to indicate that the system is disabled.

Also, power braking is a moot point if you're stuck at WOT, since the engine isn't really making a useful amount of vacuum in that situation.

Comment: Re:Free market (Score 1) 353

by Brianwa (#46627967) Attached to: If Ridesharing Is Banned, What About Ride-Trading?

The constraints on taxis in Seattle are garbage. New taxis must be hybrids. Older ones are an impressively ancient fleet of ex-police crown vics converted to run on propane. They're a fucking minority on the street, they could all be 60's muscle cars tuned so rich they can barely turn over and there wouldn't be a measurable difference in air quality in the city. The number of taxi licenses is barely enough to sorta kinda cover an average Saturday night. If there's a big event of any kind (and there's plenty of those), you'll be left waiting in the cold without a ride. If there's a hint of snow on the ground, you'll be left waiting in the cold without a ride. Most of the taxi services operate outside of the rules anyway -- for example, the big "for hire" service that pretends like you have to call in for a ride ahead of time so they're not technically a taxi service but will always pick you up on the street anyway. On the rare occasion they post a picture of the licensed driver, it only sometimes matches the driver you get. They all refuse to take the cheapest route unless you direct them at every turn (and the "for hire" service will quote you a price double their own farebook unless you negotiate in advance).

I regularly have a better taxi experience even as a white guy in 3rd world countries. If the city tried even a tiny bit to use regulation on taxis to help the city, I would stand behind them 100%. As it is, I don't consider the taxi laws in Seattle reasonable or valid until they're put to a legitimate vote by the people.

Comment: Re:sky should be the limit... (Score 2) 314

Yes, "toughness" is a technical term that refers to how much a material can yield before it breaks. In that sense, carbon fiber is not considered to be tough at all.

Crash structures that use CF normally depend on it's tendency to shatter violently at failure. If you watch any recent F1 crash that damages the monocoque, you'll see an explosion of debris -- this is by design. Done right, you can use up some of the crash energy as kinetic energy in the debris. Unfortunately, this is extremely difficult to design and test. It's also more or less a one-time use thing, I would worry that day to day bumps and scratches that happen on road vehicles might reduce the effectiveness of the structure.

The undercarriages of F1 cars are a little different, they generally have an aerodynamic undertray protected by a layer of kevlar (or similar material). This is good at reducing damage from occasional contact with the road surface and minor debris, but it depends on the undertray's ability to flex at impact and has to be replaced fairly often.

Comment: Re:Go Amish? (Score 1) 664

by Brianwa (#46312751) Attached to: Stack Overflow Could Explain Toyota Vehicles' Unintended Acceleration
There is generally a one-way valve that maintains brake booster vacuum when the throttle is open, but it's something that can fail and you won't notice it until you need it. It's worse when it happens in a turbo'd car, the turbo spools up and you find yourself with a rock solid brake pedal that stays that way for a few seconds even if you turn the engine off

Comment: Re:Go Amish? (Score 1) 664

by Brianwa (#46312705) Attached to: Stack Overflow Could Explain Toyota Vehicles' Unintended Acceleration

Cars did have this a long time ago. School buses had it up through the 90's at least, and firetrucks will probably always have a kill switch due to the potential of taking in combustible stuff through the intake.

Honestly I'm fine with using a key, it's good UI design to have an e-stop system that the user can operate without doing anything special or unusual. The only real danger is how easy it is to accidentally engage the steering column lock at the same time (or overly aggressive anti-theft systems that kick in and leave you dead in the water with no exterior lights...)

However I really don't like the new keyless systems, if I hit something and there are flames pouring out of the engine compartment and I can't get out, I'd much rather physically cut power to the fuel pump (and disable HV on a hybrid) than hold down a button I've never used before for a few seconds to send a request to a likely damaged controller to pretty please start the shutdown sequence.

Comment: Re:multiple choice (Score 1) 371

by Brianwa (#46135507) Attached to: How loud is your primary computer?

Honestly I prefer a little bit of white noise from fan turbulence over quiet electrical noise, without something to drown out the PWM noise I'll occasionally wake up in the middle of the night thinking I have a failing capacitor.

Perhaps that's a sign that I've spent too much of my life messing with electronics.

"If people are good only because they fear punishment, and hope for reward, then we are a sorry lot indeed." -- Albert Einstein