Slashdot: News for Nerds


Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!



Flies See the World In Slo-Mo, Say Researchers

ace37 Silly conclusions - shorter neural pathways (176 comments)

While size would matter, I don't see why metabolic rate should have anything to do with it. It's also funny to hear it described as 'time going slower.'

The nervous system pathways for flies are much shorter. Therefore, flies have lower lag. Go figure.

Just like an L2 cache on a computer processor, since the speed of information travel is pretty well fixed for the selected technology, using shorter path lengths yields faster response times provided the tasks are simple enough to benefit from it. Reflexes in people are like this. Detailed thinking has a lot more overhead. And while stimulus-response is more rapid for reflex type behaviors, the speed of thought is the same. (An L2 cache won't change the speed of light.) Using reflex is just a more efficient arrangement for certain types of tasks.

about 10 months ago

Apple Unveils iPhone 5C, iPhone 5S

ace37 Re:What is it with plastic? (773 comments)

The savings happen in the manufacturing process.

Typically for this type of production volume you will heat the material to a liquid state, squeeze it into a mold, let it cool, and then kick it out to make another. It's a lot easier to squeeze and pump plastic into a die, so the manufacturing costs to produce finished plastic products are much lower.

For metals, the process looks like this:

Whereas for plastics, the process looks like this:

about a year ago

Colorado Company Says It Plans To Test Hyperloop Transport System

ace37 Re:1G? (258 comments)

Eh, that math is close enough. Between 30 and 35 minutes if you just hold 1G the whole time at both ends. NY to LA is 2,790 miles.

If we assume acceleration at 1G for 15 minutes, then deceleration at 1G for 15 minutes, our average speed is the speed at 7.5 or 22.5 minutes. At 7.5 minutes, that's V_avg = 9.8 m/s^2 * 450 s = 4410 m/s, and V_max is twice that speed. Mach 1 at STP is 331 m/s, for reference.

4410 m/s * (30 min * 60s/min) = 3969 km = 2466 mi.

Add four minutes at the same average speed and we hit LA. Or pull just over 1G. Either way, it's pretty nearly 30 minutes.

1 year,14 days

Aerovelo's Human-Powered Helicopter Wins $250,000 Sikorsky Prize

ace37 Re:Ground effect (58 comments)

I forgot to mention the most important part -- the majority of the flight is done very low:

Power required is shown for rotor height of 60 cm (2 ft) above the ground. The 60-second duration flights will be flown as close to the ground as possible to increase ground effect advantages.

1 year,18 days

Aerovelo's Human-Powered Helicopter Wins $250,000 Sikorsky Prize

ace37 Re:Ground effect (58 comments)

With the speed those rotors are turning, I don't think there'd be much in the way of ground effects generated.

Just an old helicopter mechanic tho, not an aeronautical engineer So I might be completely wrong..

Typically about 1.5 rotor diameters are where it stops helping a traditional helicopeter. In this case, at 10 feet up with a 30 foot diameter, the slow rotor speed notwithstanding it will make a significant contribution. The air below the rotors can't freely move downward until the momentum of the wind dissipates; this energy creates lift.

Ben Berry from Gamera was actually a previous coworker before he went to work on their HPV project.

Source: Aero engineer, rules of thumb there are from asking around at Sikorsky years ago. Also, I don't like how they say this at all, but it at least says the ground effect is significant:

Three years ago, as Staruk and his UMD team began building their first iteration of Gamera, they quickly encountered the boundaries of current aerodynamic understanding. To rise off the ground, human-powered helicopters are helped by a phenomenon called ground effect, in which wings close to the surface of the earth experience a sharp reduction in drag. It's very helpful in getting off the ground but difficult to model. "Ground effect is a very complex phenomenon; there are all sorts of vortices," Chopra says. "You can only validate experimentally. There isn't much theory."

1 year,18 days

Star Wars Episode 4 To Be Dubbed In Navajo

ace37 Description words (155 comments)

Unlike, say, Finnish, where the Finns will typically just take an English or Swedish, Russian, &c word and spin the pronounciation to expand their tongue, the Navajo typically create a new compound word that is a description. This is a rather laborious way to rapidly expand a language. A fun example is the Navajo word for "Dog," ééch'í. That literally means "one who eats poop."

Outsiders like most of us can't cause a traditional language to adapt. The burden is on the speakers. In this case, teaching English as a second language (or French or w/e) is a better solution than trying to quickly and drastically expand a language spoken by so few, then figuring out how to translate every time we need to interact.

The Navajo language was only written in the 20th century. Even if we were able to fully expand Navajo to cover conversation with the same breadth and depth of a multicultural language like English/French/etc., and if further we could somehow teach all of the new words to all of the Navajo-speaking Indians right away, then if they don't have for instance any Navajo cabinetmakers who use the new words for cabinetry tools all the time, all those related words would die in a few years. After a decade or two, we'd be left very nearly where we are now.

Language is a living thing, and words that are long unspoken die. It's a pity, but at a certain point, a nearly dead language becomes a cultural relic, as Navajo is today. Preservation of this as a cultural relic is great, but not easy.

about a year ago

Judge Slams Apple-Motorola Suit As 'Business Strategy'

ace37 Re:Awesome (140 comments)

Do you feel the Microsoft Windows Phone licensing model fits this royalty and licensing model you suggest? Many on Slashdot claimed that the licensing approach they deployed was simply extortion to increase the cost of Android to match Windows Phone.

Fairly pricing your royalty and licensing costs for patents have always been an issue, a la Xerox. Of course, that's sort of exactly what the patent system is designed to enable - it grants a temporary monopoly to a business in exchange for public disclosure of a proprietary innovation.

It all really falls apart when the patented "innovations" are obvious to the majority of skilled designers or engineers.

about a year ago

Big Advance In Hydrogen Production Could Change Alternative Energy Landscape

ace37 Just misleading accounting / journalism (340 comments)

I don't think they're claiming to violate the laws of thermodynamics; it appears they're just using an inappropriate reference value. Based on the rest of the quote, it looks like they are using the 100% efficiency energy output from burning the biomass as the reference and comparing it to the net energy output using this method. I base that on the context from the rest of the quote:

...Even more appealing, this reaction occurs at low temperatures, generating hydrogen energy that is greater than the chemical energy stored in xylose and the polyphosphate. This results in an energy efficiency of more than 100 percent — a net energy gain. That means that low-temperature waste heat can be used to produce high-quality chemical energy hydrogen for the first time. Other processes that convert sugar into biofuels such as ethanol and butanol always have energy efficiencies of less than 100 percent, resulting in an energy penalty.

about a year ago

Man Who Pointed Laser At Aircraft Gets 30-Month Sentence

ace37 Re:Good. (761 comments)

Completely agree. It's an issue, so if they want to make a point, put the guy in jail for a week or two. More than a day but less than a month.

A 30 month sentence is not appropriate for being a douchebag. This is essentially just making an example of the guy and is unjust--the punishment doesn't fit the crime at all. Because of that, I hope this knucklehead appeals and gets off scot free.

about a year ago

Graphene Aerogel Takes World's Lightest Material Crown

ace37 Re:Enter the new airship age ... (198 comments)

So how strong is the aerogel? How big a bag can we make and have it support atmospheric pressure on the other side? That will really determine the lift efficiency.

As an ultralight foam, it has strength, but very little. You can order aerogel samples online - I did a year or two ago (glass aerogel, not graphene). It's extremely brittle and has almost no impact strength, but it has sufficient strength to be made useful. You could conceivably do what you suggest and create a bag of it, then isolate it from the exterior surface or any surface that might see impact damage. It could certainly be made to work if you had enough time, money, and talented minds.

The problem is, if airships using He aren't cost-effective today, it's looks unlikely that making airships of graphene aerogel (or any other type of aerogel) will be cost effective for many decades. As a scientific curiosity, aerogel does have a higher-than-typical chance of benefiting from a game-changing technological development, so hopefully that will be proven wrong.

about a year ago

Global Temperatures Are Close To 11,000-Year Peak

ace37 Poor that pay (416 comments)

It's the poor who will pay. I don't mean the middle class, I mean the 1 billion+ people who live on less than $1 a day. They will starve in greater numbers and die in greater numbers - they can't move, or "buy less ski equipment". I get that you don't care about that, but I hope that as a society we can bring ourselves to give a shit.

While I completely agree with your sentiment and emotional judgment, I slightly disagree with the point you make here. If I as a member of society want to reach out to the world's impoverished, I'm not going to effectively demonstrate my altruism by buying a hybrid or pushing for 'better' emissions laws. I'm going to do it by spending some of my resources supporting my favorites of the many community organizations, charities, government organizations, individual efforts, etc. who are striving to implement long term solutions to the problems of impoverished nations.

Those living on $1 a day don't give a damn about my CO2 emissions. They'll be dead before that really bites them. They want food and shelter today. The upcoming generations suffering the same fate is an issue, but with little effort, we can fix many of the the root causes over the coming decades, and it has almost nothing to do with our emissions. We should be developing and executing plans at many levels to build up basic infrastructure and establish the rule of law, and we should be looking at areas with great need and areas where we have a great ability to bring about meaningful change. Hopefully then the great grandchildren of those people can eventually join ours in a world community trying to resolve more of the global warming mess. And if not, they can all compete to buy prime Canadian and Siberian coastal real estate. Either way, nobody is starving, and our world will be much better off than if we continue to sit together arguing about emissions and giving the impoverished our pity while we leave them alone to figure out their problems.

Today, I think one of the biggest battles is to change the views of the citizens of our developed societies. I hope by the end of my lifetime we've started to believe we have a great responsibility to uplift the impoverished fellow citizens of this planet we all share.

about a year ago

LG Not Working On Windows Phone 8 Devices

ace37 Simple matter of self-interest? (123 comments)

Despite the fact that this is Slashdot, I'm surprised at the number of upvoted anti-MS epithets. I don't see how this needs to have anything to do with the merits of the OS itself when a CEO with an MBA and a Blackberry could easily come to this conclusion on a purely business case.

Neutral phone hardware developers would perceive a small market that requires investment to pursue. Most likely, LG's expected market penetration isn't large enough to justify the investment. And for the cynics, LG could also assume that, to loosely paraphrase Animal Farm, all carriers are equal to MS, but Nokia is 'more equal,' barring antitrust suits. This creates an additional small interest in starving WP of revenue to keep Nokia out of the ring.

about a year and a half ago

For Businesses, the College Degree Is the New High School Diploma

ace37 Don't write it off just yet... (728 comments)

If you're very happy with what you do and such, great, but don't shut college out based on that cost analysis. I finished my BS with $10k in debt and could have done it with none. Your college costs are not equal to your final debt. I did a community college AS degree and then finished my BS at a state school. (I did work, 20 hours a week at ~$6-7/hour.) There are many good schools, so you can filter them based on the best cost to education ratio and come up with reasonable tuition rates - just google it and see what you find. And college life can be a lot of fun depending on what you make of it.

I did a technical degree in engineering. Six years after graduating (B.S.), my salary equates to $35 an hour, I have health insurance, a month a year off, and other benefits, and in this career path, I expect my salary will double over the course of 15-20 years and then cap out. Today this buys me a nice new home, a nice new sports car, and I have enough money left over to take vacations and to save as well. Importantly, I generally like what I do at work every day and enjoy talking with and learning from intelligent peers.

If you're on the fence, remember that you can always do community college part time, right now, so you don't need to quit the job you seem to be happy with. It certainly wouldn't hurt you. If you don't like it that well, just finish the 2 year degree so you get something out of it and call it a day. You'll only have spent a few grand, you'll have learned a few things along the way, and from then on you can list a college degree if you ever need to find a new job years down the road.

about a year and a half ago

For Businesses, the College Degree Is the New High School Diploma

ace37 Limited world view (728 comments)

What does going to college tell you about a persons character? It tells me they're submissive to authority and lack initiative, which is great for many roles. A person who rejects the idea that he should sit at the feet of the wise old professor and learn and instead go out into the world and get to work making waves might not suck up what you give them and ask you if they're doing ok.

Mediocrity and reliability go to school. The worst and best reject it.

You can go about making your waves. Make big ones - I genuinely hope you do and you have a great time.

I analyze and evaluate the structural performance of supersonic fighter jets, which make waves, but of a different type entirely. My values and goals simply don't match yours.

Those of us who wish to be movers and shakers in STEM must first know the basic building blocks, and those are easily learned from the wise old professors who built these things before us. I strive for reliability in specific ways and pick an choose which authorities it is in my best interest to submit to. If you think my peers and I lack initiative and must be "mediocre," I think you need to open your eyes to different ways of viewing the world.

about a year and a half ago

For Businesses, the College Degree Is the New High School Diploma

ace37 Re:I'm getting a different message (728 comments)

I'm starting to think that a large part of the problem must be the costs varying heavily by region of the country.

My parents couldn't pay for my school, so I followed a similar path to yours. I went to a local community college at $1k a year, then I moved across the country specifically to get the best value on school while I earned my BS. I finished it with $10k in total debt. My tuition and books ran about $5000 a year for the last two years, and I worked in retail for 20 hours a week to cover my living expenses. I had seriously considered several Ivy League schools, but I couldn't justify spending the ~$20-30k/year when all I would get for it is a Bachelor's degree. My wife's medical school costs were lower than that.

Why don't families take a quick look at college costs and rankings together to find a good fit -- is it simply an issue of not knowing any better until it's too late?

about a year and a half ago

Glasgow To Be UK's First 'Smart City'

ace37 big brother (98 comments)

We went on a short self-guided car tour of Scotland this summer and were blown away at the number of cameras on the roadway. Many of the main roads had one or more speed camera covering all lanes of traffic every mile for tens of miles. I had no intention of doing any wrong, but all the 'invasion of privacy' bells were going off in my head.

I never got feelings like the system was going to be abused in any type of near term scenario, but I couldn't help but think how easy it would be for a Stalin type leader to use that envoronment to make inconvenient people disappear. In many places it is technically legal (*not that it happens*) for a police officer to bring you to jail for speeding or neglecting a turn signal during a lane change. I frequently hear the average citizen of the US commits one felony a day by being normal.

about a year and a half ago

FAA To Investigate 787 Dreamliner

ace37 Releases poisons - misrepresents the design (237 comments)

You seem to be under the impression fires in composite aircraft pose a risk of poisoning or harming passengers.

It's not that simple though. Composites (FRP) are made from a fiber and a resin, which can be thought of like a glue. Most plastics can be used as a resin. On an aircraft, they use many different resins in different places as they are tailored to the local requirements. Also, these plastics are subjected to a number of tests that are used to determine toxicity in a few reasonable ways; most of them concentrate on what happens when we burn the plastic.

Near passengers, they have requirements ensuring the parts are self-extinguishing in a short (1 minute) time frame and have no toxicity in their smoke (The flammability test is UL 94, V0 is a typical requirement; I forget the smoke and toxicity test numbers I've used). So the plastic that holds your luggage above your head is made of a less weight-efficient material because it must meet design requirements focused on passenger safety in the event of a cabin fire. And of course, in the middle of the wing, it doesn't much matter if the smoke from a fire would make a passenger sick--passengers aren't anywhere near there--but fuel is probably nearby, so the design requirements and fail-safe measures for flammability and smoke are different there and in other zones of the aircraft.

In the paper you cited, note that the focus was on emergency response personnel. If as a passenger you're exposed to such an explosion, respiration of the fibers that carry potentially toxic plastics isn't the top concern - if you're inhaling that, I would be wondering what punched a hole in the fuselage and how many people are dead. The respiration and other hazards are a big deal to a ground crew or fire department who would put out non-crash-related fires. But the words in bold, "A bigger issue: When composite burns it releases poisons," are easy to misinterpret as a major passenger safety hazard unique to this aircraft.

about a year and a half ago

The New Ethanol Blend May Damage Your Vehicle

ace37 drawbacks, fuel maps (375 comments)

Thank you for mentioning the details of what the damage means and for mentioning energy density. That's a real-world drawback we experience immediately. Ethanol does create domestic supply chains for oil for many nations though, and it's always beneficial to have a variety of effective methods to meet major demands of our societies. While the octane rating is higher for ethanol than gas, since we still buy the same ratings I can only assume oil companies are reducing the refining costs of the gasoline to minimize the net cost of the fuel.

For a data point on the car's behavior and how well optimized it would be to use a blend, I retuned the ECU on my 2006 Honda S2000 with a product by Hondata. The fuel injectors used a preset fuel-air ratio settings map for wide open throttle across the RPM range, and it used an oxygen sensor to approach ~14.7:1 air:fuel for part or light throttle. It was an open loop system with a long and short term fuel trim adjustment to keep it close to that target. The wide open throttle settings map was a little more rich than stoichiometric to keep the motor safe since running lean produces detonation--it targeted around 13:1, but the precise number seemed to vary by car model and even by individual years of the same make and model; a major trend was turbocharged cars typically were more rich than naturally aspirated vehicles. I understand my 370Z and others work generally the same way.

about a year and a half ago

FCC Chief Urges FAA To Ease Airplane Electronics Ban

ace37 Boeing's rationale (242 comments)

Boeing has an explanation of the rationale and the steps they've taken to examine the effects of electronics on aircraft in their "Aero" magazine. This is pretty old (2000) and would certainly benefit from an update, but they did real live technical investigation instead of just mixing assertions with quasi-technical arguments. A link to the full text:

TLDR Summary:
After receiving very specific, detailed claims/complaints from airlines, Boeing inspected the frequency range output and dB level of electromagnetic emissions from several specific devices. Their biggest concerns in the testing seemed to be the EMI due to frequency harmonics and interactions between devices--the premise and conceptual explanation seems unlikely but isn't completely meritless. No airplane susceptibility was demonstrated. Boeing clearly said that since they tested specific items, the testing was not conclusive for all devices and all interactions.

The excerpt on cell phones in particular deserves to be fully quoted, as it illustrates their thinking:
*Cell phone tests and analysis.*
Boeing conducted a laboratory and airplane test with 16 cell phones typical of those carried by passengers, to determine the emission characteristics of these intentionally transmitting PEDs. The laboratory results indicated that the phones not only produce emissions at the operating frequency, but also produce other emissions that fall within airplane communication/navigation frequency bands (automatic direction finder, high frequency, very high frequency [VHF] omni range/locator, and VHF communications and instrument landing system [ILS]). Emissions at the operating frequency were as high as 60 dB over the airplane equipment emission limits, but the other emissions were generally within airplane equipment emission limits. One concern about these other emissions from cell phones is that they may interfere with the operation of an airplane communication or navigation system if the levels are high enough.

Boeing also performed an airplane test on the ground with the same 16 phones. The airplane was placed in a flight mode and the flight deck instruments, control surfaces, and communication/navigation systems were monitored. No susceptibility was observed.

Telephones installed and certified on the airplane by Boeing or operators are not actually cell phones, but part of an airborne certified satellite system. These phones are electromagnetically compatible with the airplane systems because their emissions are controlled. In contrast, the emissions from passengers’ cell phones are not known or controlled in the same way as permanently installed equipment.

about a year and a half ago



Microsoft and Google Challenge US Government Gag Orders

ace37 ace37 writes  |  about a year ago

ace37 (2302468) writes "Microsoft says it plans to move ahead with a lawsuit filed against the U.S. government in June to affirm the right of businesses to disclose limited information about government demands for data made under the Foreign Intelligence Surveillance Act (FISA).

In separate legal filings, Microsoft and Google challenged the gag order that typically accompanies FISA demands for customer data. The two companies asserted that they have a First Amendment right to publish the total number of FISA requests received and the total number of user accounts covered by such requests."

Link to Original Source


ace37 has no journal entries.

Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Create a Slashdot Account