djarum72 - Slashdot User

Comment Re:"using a lot more fossil fuels than they save"? (Score 2, Interesting) 685

by djarum72 on Tuesday December 30, 2008 @09:14PM (#26274533) Attached to: Why LEDs Don't Beat CFLs Even Though They Should

The energy payback is within the first hour of use.

I figure you can fit in ~300000 CFL bulbs in a container.

http://www.google.com/search?q=12022mm+*+2352+mm+*+2395+mm+%2F+(1.7in+*+1.7in+*+4.4in)&btnG=Search

Wikipedia says it takes 85MW to bring a certain class of container ship up to speed.

http://en.wikipedia.org/wiki/Container_ship

One limit on ship size is the "Suezmax" standard, or the largest theoretical ship capable of passing through the Suez Canal, which measures 14,000 TEU. Such a vessel would displace 137,000 metric tons deadweight (DWT), be 400 meters long, more than 50 meters wide, have a draft of nearly 15 metres, and use more than 85 MW (113,987hp) to achieve 25.5 knots,

Which works out to 1/50th of a watt per bulb. Thats such a small number, trying to calculate the cruising energy seems fruitless...

http://www.google.com/search?q=85MW+%2F+14000+%2F+300000

Submission + - Vote to Eliminate Leap Seconds 6

Submitted by Mortimer.CA on Sunday November 18, 2007 @04:31PM

Mortimer.CA writes: As mentionted on Slahdot previously, there is a proposal to remove leap seconds from UTC (nee 'Greenwich' time). It wil be put to a vote to ITU member states, and if 70% agree, the leap second will be eliminated by 2013. There is some debate as to whether this change is a good or bad idea. One philosophical point opponents make is that the 'official' time on Earth should match the time of the sun and heavens. People with appliances that blink '12:00' can probably ignore this issue.

Submission + - VM-based rootkits proved easily detectable (stanford.edu)

Submitted by paleshadows on Sunday September 30, 2007 @11:55PM

paleshadows writes: A year and a half has passed since SubVirt, the first VMM (virtual machine monitor) based rootkit, was introduced. The idea spawned two lively slashdot discussions: the first, which followed the initial report about SubVirt, and the second, which was conducted after Joanna Rutkowska has recycled the idea (apparently without giving credit to the initial authors). Conversely, in this year's HotOS workshop, researchers from Stanford, CMU, VMware, and XenSource have published a paper titled " Compatibility Is Not Transparency: VMM Detection Myths and Realities" which shows that VMM-based rootkits are actually easily detectable. The introduction of the paper explains that

"While commodity VMMs conform to the PC architecture, virtual implementations of this architecture differ substantially from physical implementations. These differences are not incidental: performance demands and practical engineering limitations necessitate divergences (sometimes radical ones) from native hardware, both in semantics and performance. Consequently, we believe the potential for preventing VMM detection under close scrutiny is illusory — and fundamentally in conflict with the technical limitations of virtualized platforms."

The paper concludes by saying that

"Perhaps the most concise argument against the utility of VMBRs (VM-based rootkits) is: "Why bother?" VMBRs change the malware defender's problem from a very difficult one (discovering whether the trusted computing base of a system has been compromised), to the much easier problem of detecting a VMM."

Submission + - Driving on starch?

Submitted by

Roland Piquepaille

on Saturday May 26, 2007 @12:36PM

Roland Piquepaille writes: "Using sugar contained in corn or potatoes to build hydrogen-powered fuel cells has already been done. But now, a team of U.S. researchers has developed a new sugar-to-hydrogen technology. Why not put the starch inside the tank of your car? With the help of 13 specific enzymes, "a car with an approximately 12-gallon tank could hold 27 kilograms (kg) of starch, which is the equivalent of 4 kg of hydrogen. The range would be more than 300 miles, estimates one of the researchers. One kg of starch will produce the same energy output as 1.12 kg (0.38 gallons) of gasoline." The beauty behind this idea is that no special infrastructure would be needed. Starch could be distributed by your local grocery store. Here is a link to many additional references."

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