That doesn't make much sense.. most EV's are more efficient at higher motor RPM's. The series DC motors that are popular in conversion EVs have gobs of low end torque, but are most efficient at their RPM limit (typically about 5000 RPM). My MR2 is best left in third gear, the motor still makes enough low end torque for good acceleration, and reachs efficient cruising at about 45mph (typically the max speed for my commute). On the interstate I occasionally jump up into 4th to avoid the 5000rpm redline.
You problem was more likely related to the torque converter. Most hobbyist conversion do not use automatic transmissions becuase they are not designed for the high low rPM torque of EV's. In a gas car you upshift to increase efficiency (slowing the motor down) in an EV you downshift (speeding the motor up). A tranny designed for a gas engine will not know that.
Also automatics expect the motor to be constantly turning, that idle is used to run the transmissions internal oil pump. Without the idle the tranny drops into nuetral and it can take several seconds of motor turning before it drops into gear and starts moving. In an EV the electric motor has no need to idle so idling for the tranny's sake is wasteful.
I was thinking about all the power consumed by idle wall warts around the house. The average wall wart wastes 1-3 watts or 9-27kwh a year. Not much, but multipled by the several dozen I have in operation its a lot. (Some studies have shown that "idle" electronics consume 11% of a home's average power usage)
Most of this is becuase cheap low powered power supplies are really inefficient, often wasting more power than the device uses.
My idea was to modify most of my devices to run on 48VDC using DC/DC converters. Then use my many ethernet jacks to send power over ethernet to each device, supplied from one large efficient (battery backed) 48v supply. I got a few prototypes done: the alarm clock (now it needs ntp support) cordless phone and cell phone charger but got bored and overwhelmed by the sheer number of devices.
Many smaller companies do not play close attention to their phone bills. They might squeeze every penny when buying new computers or office furniture, but often the phone system and lines are whatever the phone vendor installed 6 years ago. Just like cellphones the phone provider doesn't tell you when a new cheaper plan becomes available.. and the market has heated up.. plenty of competition (at least for business services) means everyone is cutting prices.
You're probably no longer in a contract with one vendor anymore, and you often have choice for local service, or even VOIP providers. Ask accounting to cough up the phone bills (hey telecom is an information service, therefore its IT's responsibility)
It is not uncommon to find that a company with 50 employees is paying $2-3000 a month for long distance, internet and local phone service. Often there are a few old "modem" lines no one is using.. too much voice T1 capacity. Whatever.
These days you can get great deals with non-incumbant carriers, epecially in the combined data/telephone market. $400/month for a T1 with shared voice and data is not uncommon. (whatever T1 bandwidth is not used on voice is allocated over to data) A T1 for data or voice only often runs $700-$1000/month. Saving a few hundred bucks per month gets multipled by 12 for thousands per year in savings. There is nothing like saying you just saved the company the cost of your salary.
Is it just me or did the article quote music industry folks as saying the software must work becuase 95% of the hits of the last decade scored highly. The software is a mathmatical model based on the hits of the last century.. so of course it scores them highly.
Asterisk can be pretty secure.. and it can be pretty unsecure depending on your config. SIP and most of the VOIP protocols are by default unencrypted. VPN or VLAN should be used whenever privacy is required.
The big thing about Asterisk is control..
My Mitel phone systems are not my own despite having paid up front for them. They have licensing, limited documentation and pay for software upgrades. Mitel won't even let me pay to attend a user level training course unless I have a "endorsement" from the vendor who sold me the hardware. Since becomeing a vendor requires a $20k initial capitol outlay, I have a limited choice of vendors.
With Asterisk I can roll my own or pay someone to do it for me.. and if the vendor tries to squeeze me I can swap vendors. Asterisk is open enough and well documented: even if I don't understand everything, I still can understand enough to tell when the vendor is stretching the truth. Bad customer service is pretty much standard in the telecom world.
My biggest gripe about Asterisk is that is it do not have the fancy (and propriatary) digital phones with multiple soft line and speed dial keys... but thats a trade off.
Open Source gives the customer leverage, and levels the paying field. And sometimes it even costs less.
There is a fairly entertaining Sci-Fi book: "Thunderstrike" by Michael McCollum where a giant earth killing comet is instead directed to crash into the moon.
Something to think about, given the Moon's low gravity, and lack of atmosphere, how much of the ejecta ends up crashing into earth anyway?
Fuel Cells are the answer, and it is just a matter of time before cell fuels like they plan for cell phones will be available for electric cars
Ah yes.. the "fuel cell will solve all our problems" argument. Guess what, fuel cells are just non-rechargeable batteries. (refillable though)
Lets chase hydrogen for a sec (methane is a terrible greenhouse gas, and there just aren't enough cow farts and rotting garbage to produce enough to run even small fraction of the worlds cars) Hydrogen fuel cells are great, no pollution at the tailpipe.. and quick recharge, just plug a hose in and fuel up just like the Arnold the Govanator in that great PR photo.
The problems are actually a little more difficult than the photo implys. #1, we have no hydrogen infrastructure, it would have to be built. Hydrogen is diffuse and compressing it to make it denser takes lots of energy (about to 70% of the energy stored if you want to liquify it) . So transportation costs are high by truck. It can only be shipped by special pipelines, which costs about 1 mil $'s per mile (compared to $100,000 for a petrol pipeline). There are no options to add a scent to hydrogen (like we do with propane or NG) that won't contaminate the fuel cell, so hydrogen leaks are fairly difficult to detect. Worst of all is how do we make it. The process of cracking water into hydrogen and oxygen and then combining in a fuel cell is about 50% efficent, batteries are closer to 80% efficent. The fuel cell itself generally uses platinum as a catylst and it takes almost $300 of platinum per kw of output power. The US DOE estimates that the total cost per kw would need to fall below $45 for the entire fuel cell to be competitive with gasoline. Even some of the strongest advocates of fuel cells admit we are 10 years from the first mass production Fuel Cell Vehicle, and probably 30 years from having enough of them on the road to make a dent in our gasoline usage.
Battery Electric Vehicles are here today, are very energy efficient, simple and low maintaince. When fuel cells get their bugs worked out, it won't be a major change to switch.
It's somewhat misleading to compare these to your car, because your car carries around a lot of extra weight for safety.
Do not fall into the trap of thinking that safety is directly linked to weight, or that safety systems are heavy.
Years of crash test research (most in Europe) has show that the energy absorbing design of the vehicle has the greatest effect on safety. You want a strong passenger cage with good crumple zones on all sides. (Side impacts are particularly deadly becuase there is almost no crumple zone, and basically no protection for the drivers head and torso above the door sill. SUVs are particularly deadly becuase their tall hoods and grills often ride over the door still of the shorter car).
Now the strong passenger cage can be heavy, if you want to keep making it out of inexpensive steel (think Volvo)... if you want light and strong there are alloys and composites that will do the job (used extensively in racing), but they are more expensive. The fuel savings from making the car lighter would pay for the additional costs, but Auto manufacturers don't believe that their costumers care about lifecycle costs, only sticker price.
1. Charging. You need to let these cars sit for a period of time between use to let the batteries top up. Without that, it's just a very expensive paperweight (and not a very good one at that.)
Most EVs can quick charge to 80% capacity in very short times (less than 1hr). Odds are your car will be charged by the time you need it again. It certainly works for the daily commuter where your driving a known trip and have overnight to charge. 80% of Americans drive less than 40 miles per day.
2. Battery life. A typical Li-ion battery will lose twenty percent of its capacity every year, from the day that they are manufactured.
Be careful quoting statitics from laptop scale Lithium Ion batteries. Large scale batteries are a different animal. The 20% loss in capacity per year for laptop and cell phone batteries is due to corrosion of the positive electrode. In a laptop battery each cell is about the size of an A battery and has a very small positive electrode. A car sized battery has much larger electrodes, and corrosion has a negligble effect on overall capacity.
Would you buy a new set of batteries (see next point) every three years, or even more often?
It depends... I would look at lifecycle costs. The higher efficency of EVs means that even though electricity costs more per unit of work, I still get a lower cost per mile. If the difference between cost per mile is enough to pay for battery replacement (however often) I still "win."
A odd sidenote.. Lithium Ion, like most battery chemistries, get more cycles if your average cycle is shallow. According to one battery manufacturer a 200 mile pack of LIon batteries used daily for my 12 mile trip to work, would last 10,000 cycles, or 120,000 miles and over 27 years of use. Now that same set of batteries used for 150 mile trips to work would only last 2000 cycles but would be driven 300,000 miles. Weird eh?
3. Cost. How much will those Li-ion batteries cost? (Hint: they're not cheap. My PowerBook needs a battery that costs $US130. And that's just a tiny fraction of what a car engine would need...)
Its all about economy of scale. Your laptop uses a standard sized lithium cell, that is mass produced and is fairly inexpensive. (Less than $2.50 each, and most batteries have about 8 of them.) Then those mass-produced cells are stuffed in a propriatary package with some simple, but also custom control electronics... and now competition is harder, and prices rise. Lithium isn't cheap, but in mass production car sized batteries would not effect the sticker price of a comparable car.
Car manufactureres tend to resist _any_ market change, usually by saying that consumers won't pay for it. Many SUVs are still selling with 10-15 year old 2 valve engine designs, becuase the auto manufacturers say that given the choice between paying $200-$300 more on the sticker for a 2-3 mpg improvement, or $300 for the DVD player that American consumers want the DVD. (4 or more valve designs are more expensive to build but are used on most cars becuase of stricter fuel economy and emissions requirements)
In the late 60's the auto companies said that consumers wouldn't pay for safer cars, or better emission controls... all of these things did make a difference. There might not be a conspiracy, just the normal behavior of a large company trying to maximize benefits to shareholders while ignoring society as a whole...
Heck with the bicycle, you attach it to the roof of your electric car and drive forever.
You wouldn't believe how many "why don't you hook an alternator to the wheels or put a windmill on the top.. then it could recharge the batteries as you drive" questions I get concerning my electric car.
"Dammit..in this house we obey the laws of thermodynamics"
According to a friend of mine who does the renewable energy buying for Austin Energy the cost of utility owned windpower is _cheaper_ than coal. Cheap enough that the utility is installing 1-2 MW turbines as fast as possible (especially since the "green" power produced can be sold at a premium).
Storage is an issue, most wind power in Texas is generated in Spring, when load is light. The utility has actually analyzed the options and found that using windpower to freeze a lake during spring, and thaw it during summer to run the shared cooling loops downtown makes economic sense.
Sadly even "computer crime units" of the local PD tend to be disinterested in this kinda thing. Unlike this case, most ebay fraud is hard to document, and each individual auction is less than $5000 (which has been the magic number that has to be exceeded to get the cops interest. Worse local PDs tend to work poorly with the folks in other states.
The postal inspectors are great for this thing, they are highly professional, and pretty much deal only in mail fraud, so they're experts.
Ebay fraud is especially tempting to theives, since a lot of the information is in EBay's hands, and they only share with the police, and the criminal seldom need to deal with the victims face to face. This lessens the odds of a victim settling the score by with a savage beating.
The Internet is a great tool, it simplifies fraud just as well as any other business.
Everything was fine, up until they tried to prevent peopel from redistributing code.
I do not see any evidence they are trying to prevent people from redistributing the code. The Seavsoft follks see to be upset about other sites that make the seavsoft binaries available without the source.
I just logged into seavsoft's site and as a paying licensee I can still download both the binaries and the source. Sveasoft is doing nothing wrong. as far as I can tell (and in fact already has a letter from the FSF blessing their business model).
The sites that have reposted the seavsoft binaries without offering source are violating the GPL... Now its probably not Sveasoft's place to go after these guys but OTOH the violators are trying really hard to piss off Sveasoft.
Sveasoft is using the GPL in a creative, but legal way. Put this way: if you pay them for a license you get access to prerelease binaries and sourcecode. You then have a choice of licenses: you can choose to continue to follow the Seavsoft license, which will get you access to future revs of the code, or you can redistribute under the terms of the GPL which results in termination of the Seavsoft license and access to future revs.
Our mount was two 1x4" pieces of lumber. One piece was laid on the window sill, parallel to the window glass and held in place with the wood jawed clamps available at most home stores. The other piece was screwed to it sticking into the room about 1" (the depth of the dish). The dish pointed at a slight angle thru the glass.
It worked well until a tree was planted in front of the window dropping the signal strength to below functional levels with the window closed. With the tree to hide our efforts, the screen was removed and the mount flipped around with the dish outside the window. Now the dish was outside our apartment, but the management ignored it.
When I was a Dell tech a customer called in reporting they had backed over a Latitude Portable with their SUV. Not once, but 7 times. The customer stated they couldn't figure out what the bump was, so they went forward and back trying to figure it out. Good thing it wasn't their kids arm.
At another job I once had a brand new Toshiba brought to the store as non-functional. The Lysol the customer had sprayed it with failed to cover the stench of cheap beer. It had been spilled on the keyboard and removed the traces from the PC board on the bottom of the harddrive. After being presented with a $2000 repair bill on a $3000 system the customer took it back unrepaired... and I suspect he returned it to Best Buy....
Assuming that there is one AP per classroom, and connections to adjacent classrooms do not work well:
Just have the campus electrician wire the AP to a lightswitch next to the blackboard. Then the professor can make their own decision on wireless access. The user interface requires little maintainance, is easy to use and difficult to hack without getting caught or electrocuted.
Not really a fair comparison since driving style has a lot to do with fuel economy. Your buddy with the 31.5 either has a commute with much freeway driving, or has a good driving style.
For example some drivers can reach 90-100mpg in the Honda Insight. Typically this is done with nice gradual acceleration, and shifting in such a way that the electric motor is used heavily. Keep the windows rolled up, and the AC off (AC can account for 2-3mpg). Nice slow deacceleration forces the most regenerative energy to be stashed back in the batteries. (Only about the first 20% of braking force comes from the regen system,press harder on the pedal and the mechnical brakes kick in, wasting energy as heat)
Most drivers average about 40-50 mpg, and lead footed individuals can drag the Insight down to about 30mpg or less.
Driving style affects normal cars almost as much, but few people track their mileage closely. The hybrids typically have large gauges telling current fuel economy... much harder to ignore.
Also sticker mpg is based on 55mph max speed.. Aerodynamic lose increases as the square of speed.. driving 70mph instead of 55mph can make a several mpg difference as well.
Very nice, clean design overall. I'd like to know who the supplier was for the rack cases, or if they had them made custom. I've seen the half cases with the ports on the front before, but I have not been able to locate a US supplier.
It appears that the nodes are half sized, allowing for 40 systems per side, or 80 systems total. The null modem console cables connecting node pairs together is clever... if any one machine fails, you can restart it as long as its neighbor is still alive.
TMI was a case of automatic safety systems being overrided by undertrained human operators. As the story paragraph mentioned, TMI was a stark lesson in control systems design.
In the control room the operators had no feedback about how much water was in the reactor core, just one gauge showing the level of water in the pressurizer tank near the top of the system. When a valve near the top of the pressurizer stuck open (referred to as the PORV or pressure operated relief value) the steam that normally kept the water near the bottom of the pressuizer tank started leaking out. More water flashes to steam.... and TMI is now losing water. The operators saw the opposite, the water level was rising on the level gauge for the pressurizer and they started reducing and eventually draining water out of the system thinking some malfunction was causing water to be introduced. None of the operators was able to step back from the initial theory that water levels were rising, despite large amounts of contradicting information. (Hours into the incident an off-duty operator arrived and with a fresh set of eyes figured out what was happening)
There are a lot more things that went wrong that night... (the initial shutdown was caused by water accidentially getting into the compressed air supply for the pneumatic control systems in the steam room, a valve closed at the wrong time and burst one of the steam lines to the power turbines)
TMI is a fascinating example of how multiple redundant systems still can fail, given a long string of "coincidences" One can argue that failures of this type are like winning the lotto, their is little chance of it happening on on particular day, but given enough days it is certain to happen to someone. Hence the need for "fail safe" designs.
I think it is apparent that the writer has little familiarity with the free/open software environment. I would not be surprised to find that many of his views were formed by reading headlines or by the arguments of the unnamed youngster.
The writer is correct from his point of view: if you are already employeed writing closed software for sale open/free software gives you no benefit. It competes for customers, and the free/open software developers do not necessarily get payment in return for their work.
The truth is a little fuzzier: most software in this world is not written for commercial sale. It is written within companies to solve particular problems in support of business processes. If no commercial alternative exists, or if an external entity cannot create a custom product then a business creates their own. Since this development is a sunk cost, sharing it, and possibility benefiting from someone else's work has no negative effects on the bottom line.
The other angle is this: as a purchaser of business software I look more favorably on open than closed software. With closed software the vendor controls me. The vendor can increase costs, withdraw support and make pretty much whatever demands he wants. With open software I have a escape clause... if my relationship with the vendor becomes negative, or I need a feature the vendor cannot/will not supply I can always take the source and find someone else to support me. If customers start demanding this option, closed vendors may not want to become open, but they may have to in order to compete. (Free/open products give control back to the consumer, a plus for the consumer, a minus for the producer)
> The cost of the replacement screen was over $900.
I would still recommended buy the "damage coverage" warrenty, but it is less important than it used to be. Cracked LCDs used to cost $900, but newer laptops replacement screens can be had for $250-$400. OTOH, with laptops coming out of cases for airport screenings the number of dropped and cracked screens is definately rising.
SPF has nothing to do with banning dialup. It just allows domain owners to decide where mail should come from.
If you're sending mail direct from your dialup, odds are you have you own domain. So as the domain owner you post an SPF record that says mail from mydomain.com should only come from (insert IPs used by your diaup provider)
Now if you are sending direct and using for example aol.com in your "From:" field, your mail might get bounced (right now its more likely to be flag as possible spam), since AOL has said that want you to use their smarthost if your sending mail with a From aol.com address.
The only problem with SPF right now... no Spamassassin support.
AFAIK slashdot does not cache, but instead builds static pages from the dynamic content at regular intervals. Logged in users see a dynamic page, but most users just see the static page that is built from dynamic content
IMHO if content is not different for each user it is not really dynamic. (Plenty of sites are dynamic becuase they can be, not really becuase they should be). Even if it is mostly static with just a few dynamic elements (Like a Welcome: *username*) see if your content system supports precompiling templates or the like.
If your content changes slowly, and you're just using the db stuff to ease administration and content management, consider doing a pull from the CMS to static files.
Almost all webservers are tuned to stream data from disk to net _fast_. An apache box in a low end Pentium system can saturate a T1 pretty easily servering dynamic content. Almost all modern hardware should be able to do much more.
Another option is to speed up the database stuff... 20-30 concurrent users isn't all that much. Have you implemented connection pooling, and properly tuned your indicies for the more common queries. (Some db servers cache queries quite well). For example oracle connections can take up to 2 seconds, and an average of about 500ms to setup. If you are creating and destroying a db connection for each page request, it really slowes things down... connection pooling means only connecting to the db at first page load.
Otherwise, just use squid. It works. I would recommend setting up a linux box on some outdated piece of hardware. Yeah its not windows, but this is going to be a appliance like application. Just set and forget. You gain to added advantage that the squid/linux box will diversify your network a bit, and it protects IIS against many attacks.
I am pretty sure they are in fact D cells, just welded together and bundled into a single battery pack.
Nominal voltage of a NiMH cell is 1.2V, so that would be 120 cells. One battery site lists the weight of a single D cell at 163g, so 120 of the would be 19560g or 19.5kg.
Doing a quick google search, this article repeats my theory above, as does this one.
Its cheaper to use an already existing battery type, than to build one special for the car.
Interestingly the battery store listed above offers the Nimh D cells for $6.83 in quantities above 100. Thats $890.. and Honda currently lists the replacement cost of the Insight battery at $1500.
Yeah, your lowly little AA rechargable would happily dump 6,120A in 1 second if the short circuit had small enough resistance.
You're neglecting the fact that a battery is not a perfect voltage source. To correctly model a battery you must put a resistance in series with the voltage source, since all batteries have a internal resistance.
That having been said.. a standard D NiCd cell can put out almost 1000amps for short periods. This is why fuses and other standard short circuit protection devices were invented. Most battery packs have at least one internal fuse, larger ones will have several to handle the possibility of intra-pack shorts.
I'd love to know the Ah specification for the battery in the back seat of the Honda Hybrids. It absolutely terrifies me to know that idiots are buying them and driving around.
"a total output of 144 V and 6.5 amp-hours" for the Honda Insight... about 6.0amp/hr for the Civic. The batteries themselves are Nickel Metal Hydride "D" cells.
The batteries are time bombs, hazardous waste and chemical burn nightmares.
Hazardous waste? There are far more Superfund cleanup sites caused by leaking gasoline/oil storage than battery manufacture. Lead Acid batteries are the most recycled item in the United States (more than AL cans). 95% of the battery itself can be recycled (the plastic case is often discarded. Lithium should ideally not be disposed of in the trash, but in a LiOH battery it is pretty stable. Lead Acid does offer the possibility of Acid burns, but the dilute acid is really only a problem is it gets in your eyes.. on the skin it typically only causes irration and a mild rash. And don't forget.. the explosive potential of the gasoline in your car is equal to almost 3 sticks of dynamite.
The charging process is inefficient at best (<50%).
Not sure where you get your numbers... Lead Acid batteries charging in large strings is over 90% efficent. From powerplant to road electric cars are more than twice as efficent as burning gasoline in an internal combustion engine (more than 50% of the energy in the coal burned in the powerplant ends up moving the car, as opposed to only about 11% of the energy of gasoline). Better still if you factor the environmental/energy cost of transporting, and refining the fuel (Think of the fuel it takes to run the tanker that brings the gasoline to you).
A gasoline car will always emit the same, or more pollution during its life. Most powerplants get cleaner everyday from tighter environmental resitrictions. My electric car is powered entirely from renewable energy (wind) and is more or less "zero emmission" because of it.
How many new coal and nuclear power plants are gonna have to be built when 10,000,000 Los Angeles commuters start plugging in their electric cars every night?
Most electric cars will be charged during the evening or early morning hours when demand for electricity is at its lowest. The EPA estimates that over half of the cars in California could be electric, and no additional power generation would be required. Indeed, one company showed a prototype electric car that could be used as battery when plugged in, and provide desperatly needed peaking power to avoid brownouts.
I have actually seen a video (by Valence) of a lithium ion (cobalt) battery being driven into thermal runaway... it goes off like a torch. Not something you want to have happen, but the safety systems in the batteries themselves are excellent. There have been only a handful of battery fires in the millions of currently deployed batteries.
I realize this is slashdot.. but if you want people to believe your college educated it never hurts to do some research before opening your mouth.
Slashdot Mirror
That doesn't make much sense.. most EV's are more efficient at higher motor RPM's. The series DC motors that are popular in conversion EVs have gobs of low end torque, but are most efficient at their RPM limit (typically about 5000 RPM). My MR2 is best left in third gear, the motor still makes enough low end torque for good acceleration, and reachs efficient cruising at about 45mph (typically the max speed for my commute). On the interstate I occasionally jump up into 4th to avoid the 5000rpm redline.
You problem was more likely related to the torque converter. Most hobbyist conversion do not use automatic transmissions becuase they are not designed for the high low rPM torque of EV's. In a gas car you upshift to increase efficiency (slowing the motor down) in an EV you downshift (speeding the motor up). A tranny designed for a gas engine will not know that.
Also automatics expect the motor to be constantly turning, that idle is used to run the transmissions internal oil pump. Without the idle the tranny drops into nuetral and it can take several seconds of motor turning before it drops into gear and starts moving. In an EV the electric motor has no need to idle so idling for the tranny's sake is wasteful.
I was thinking about all the power consumed by idle wall warts around the house. The average wall wart wastes 1-3 watts or 9-27kwh a year. Not much, but multipled by the several dozen I have in operation its a lot. (Some studies have shown that "idle" electronics consume 11% of a home's average power usage)
Most of this is becuase cheap low powered power supplies are really inefficient, often wasting more power than the device uses.
My idea was to modify most of my devices to run on 48VDC using DC/DC converters. Then use my many ethernet jacks to send power over ethernet to each device, supplied from one large efficient (battery backed) 48v supply. I got a few prototypes done: the alarm clock (now it needs ntp support) cordless phone and cell phone charger but got bored and overwhelmed by the sheer number of devices.
Many smaller companies do not play close attention to their phone bills. They might squeeze every penny when buying new computers or office furniture, but often the phone system and lines are whatever the phone vendor installed 6 years ago. Just like cellphones the phone provider doesn't tell you when a new cheaper plan becomes available.. and the market has heated up.. plenty of competition (at least for business services) means everyone is cutting prices.
You're probably no longer in a contract with one vendor anymore, and you often have choice for local service, or even VOIP providers. Ask accounting to cough up the phone bills (hey telecom is an information service, therefore its IT's responsibility)
It is not uncommon to find that a company with 50 employees is paying $2-3000 a month for long distance, internet and local phone service. Often there are a few old "modem" lines no one is using.. too much voice T1 capacity. Whatever.
These days you can get great deals with non-incumbant carriers, epecially in the combined data/telephone market. $400/month for a T1 with shared voice and data is not uncommon. (whatever T1 bandwidth is not used on voice is allocated over to data) A T1 for data or voice only often runs $700-$1000/month. Saving a few hundred bucks per month gets multipled by 12 for thousands per year in savings. There is nothing like saying you just saved the company the cost of your salary.
Is it just me or did the article quote music industry folks as saying the software must work becuase 95% of the hits of the last decade scored highly. The software is a mathmatical model based on the hits of the last century.. so of course it scores them highly.
Asterisk can be pretty secure.. and it can be pretty unsecure depending on your config. SIP and most of the VOIP protocols are by default unencrypted. VPN or VLAN should be used whenever privacy is required.
The big thing about Asterisk is control..
My Mitel phone systems are not my own despite having paid up front for them. They have licensing, limited documentation and pay for software upgrades. Mitel won't even let me pay to attend a user level training course unless I have a "endorsement" from the vendor who sold me the hardware. Since becomeing a vendor requires a $20k initial capitol outlay, I have a limited choice of vendors.
With Asterisk I can roll my own or pay someone to do it for me.. and if the vendor tries to squeeze me I can swap vendors. Asterisk is open enough and well documented: even if I don't understand everything, I still can understand enough to tell when the vendor is stretching the truth. Bad customer service is pretty much standard in the telecom world.
My biggest gripe about Asterisk is that is it do not have the fancy (and propriatary) digital phones with multiple soft line and speed dial keys... but thats a trade off.
Open Source gives the customer leverage, and levels the paying field. And sometimes it even costs less.
There is a fairly entertaining Sci-Fi book: "Thunderstrike" by Michael McCollum where a giant earth killing comet is instead directed to crash into the moon.
Something to think about, given the Moon's low gravity, and lack of atmosphere, how much of the ejecta ends up crashing into earth anyway?
Fuel Cells are the answer, and it is just a matter of time before cell fuels like they plan for cell phones will be available for electric cars
Ah yes.. the "fuel cell will solve all our problems" argument. Guess what, fuel cells are just non-rechargeable batteries. (refillable though)
Lets chase hydrogen for a sec (methane is a terrible greenhouse gas, and there just aren't enough cow farts and rotting garbage to produce enough to run even small fraction of the worlds cars) Hydrogen fuel cells are great, no pollution at the tailpipe.. and quick recharge, just plug a hose in and fuel up just like the Arnold the Govanator in that great PR photo.
The problems are actually a little more difficult than the photo implys. #1, we have no hydrogen infrastructure, it would have to be built. Hydrogen is diffuse and compressing it to make it denser takes lots of energy (about to 70% of the energy stored if you want to liquify it) . So transportation costs are high by truck. It can only be shipped by special pipelines, which costs about 1 mil $'s per mile (compared to $100,000 for a petrol pipeline). There are no options to add a scent to hydrogen (like we do with propane or NG) that won't contaminate the fuel cell, so hydrogen leaks are fairly difficult to detect. Worst of all is how do we make it. The process of cracking water into hydrogen and oxygen and then combining in a fuel cell is about 50% efficent, batteries are closer to 80% efficent. The fuel cell itself generally uses platinum as a catylst and it takes almost $300 of platinum per kw of output power. The US DOE estimates that the total cost per kw would need to fall below $45 for the entire fuel cell to be competitive with gasoline. Even some of the strongest advocates of fuel cells admit we are 10 years from the first mass production Fuel Cell Vehicle, and probably 30 years from having enough of them on the road to make a dent in our gasoline usage.
Battery Electric Vehicles are here today, are very energy efficient, simple and low maintaince. When fuel cells get their bugs worked out, it won't be a major change to switch.
It's somewhat misleading to compare these to your car, because your car carries around a lot of extra weight for safety.
... if you want light and strong there are alloys and composites that will do the job (used extensively in racing), but they are more expensive. The fuel savings from making the car lighter would pay for the additional costs, but Auto manufacturers don't believe that their costumers care about lifecycle costs, only sticker price.
Do not fall into the trap of thinking that safety is directly linked to weight, or that safety systems are heavy.
Years of crash test research (most in Europe) has show that the energy absorbing design of the vehicle has the greatest effect on safety. You want a strong passenger cage with good crumple zones on all sides. (Side impacts are particularly deadly becuase there is almost no crumple zone, and basically no protection for the drivers head and torso above the door sill. SUVs are particularly deadly becuase their tall hoods and grills often ride over the door still of the shorter car).
Now the strong passenger cage can be heavy, if you want to keep making it out of inexpensive steel (think Volvo)
1. Charging. You need to let these cars sit for a period of time between use to let the batteries top up. Without that, it's just a very expensive paperweight (and not a very good one at that.)
Most EVs can quick charge to 80% capacity in very short times (less than 1hr). Odds are your car will be charged by the time you need it again. It certainly works for the daily commuter where your driving a known trip and have overnight to charge. 80% of Americans drive less than 40 miles per day.
2. Battery life. A typical Li-ion battery will lose twenty percent of its capacity every year, from the day that they are manufactured.
Be careful quoting statitics from laptop scale Lithium Ion batteries. Large scale batteries are a different animal. The 20% loss in capacity per year for laptop and cell phone batteries is due to corrosion of the positive electrode. In a laptop battery each cell is about the size of an A battery and has a very small positive electrode. A car sized battery has much larger electrodes, and corrosion has a negligble effect on overall capacity.
Would you buy a new set of batteries (see next point) every three years, or even more often?
It depends... I would look at lifecycle costs. The higher efficency of EVs means that even though electricity costs more per unit of work, I still get a lower cost per mile. If the difference between cost per mile is enough to pay for battery replacement (however often) I still "win."
A odd sidenote.. Lithium Ion, like most battery chemistries, get more cycles if your average cycle is shallow. According to one battery manufacturer a 200 mile pack of LIon batteries used daily for my 12 mile trip to work, would last 10,000 cycles, or 120,000 miles and over 27 years of use. Now that same set of batteries used for 150 mile trips to work would only last 2000 cycles but would be driven 300,000 miles. Weird eh?
3. Cost. How much will those Li-ion batteries cost? (Hint: they're not cheap. My PowerBook needs a battery that costs $US130. And that's just a tiny fraction of what a car engine would need...)
Its all about economy of scale. Your laptop uses a standard sized lithium cell, that is mass produced and is fairly inexpensive. (Less than $2.50 each, and most batteries have about 8 of them.) Then those mass-produced cells are stuffed in a propriatary package with some simple, but also custom control electronics... and now competition is harder, and prices rise. Lithium isn't cheap, but in mass production car sized batteries would not effect the sticker price of a comparable car.
Car manufactureres tend to resist _any_ market change, usually by saying that consumers won't pay for it. Many SUVs are still selling with 10-15 year old 2 valve engine designs, becuase the auto manufacturers say that given the choice between paying $200-$300 more on the sticker for a 2-3 mpg improvement, or $300 for the DVD player that American consumers want the DVD. (4 or more valve designs are more expensive to build but are used on most cars becuase of stricter fuel economy and emissions requirements)
In the late 60's the auto companies said that consumers wouldn't pay for safer cars, or better emission controls... all of these things did make a difference. There might not be a conspiracy, just the normal behavior of a large company trying to maximize benefits to shareholders while ignoring society as a whole...
Heck with the bicycle, you attach it to the roof of your electric car and drive forever.
You wouldn't believe how many "why don't you hook an alternator to the wheels or put a windmill on the top.. then it could recharge the batteries as you drive" questions I get concerning my electric car.
"Dammit..in this house we obey the laws of thermodynamics"
According to a friend of mine who does the renewable energy buying for Austin Energy the cost of utility owned windpower is _cheaper_ than coal. Cheap enough that the utility is installing 1-2 MW turbines as fast as possible (especially since the "green" power produced can be sold at a premium).
Storage is an issue, most wind power in Texas is generated in Spring, when load is light. The utility has actually analyzed the options and found that using windpower to freeze a lake during spring, and thaw it during summer to run the shared cooling loops downtown makes economic sense.
Mark
Sadly even "computer crime units" of the local PD tend to be disinterested in this kinda thing. Unlike this case, most ebay fraud is hard to document, and each individual auction is less than $5000 (which has been the magic number that has to be exceeded to get the cops interest. Worse local PDs tend to work poorly with the folks in other states.
The postal inspectors are great for this thing, they are highly professional, and pretty much deal only in mail fraud, so they're experts.
Ebay fraud is especially tempting to theives, since a lot of the information is in EBay's hands, and they only share with the police, and the criminal seldom need to deal with the victims face to face. This lessens the odds of a victim settling the score by with a savage beating.
The Internet is a great tool, it simplifies fraud just as well as any other business.
Everything was fine, up until they tried to prevent peopel from redistributing code.
I do not see any evidence they are trying to prevent people from redistributing the code. The Seavsoft follks see to be upset about other sites that make the seavsoft binaries available without the source.
I just logged into seavsoft's site and as a paying licensee I can still download both the binaries and the source. Sveasoft is doing nothing wrong. as far as I can tell (and in fact already has a letter from the FSF blessing their business model).
The sites that have reposted the seavsoft binaries without offering source are violating the GPL... Now its probably not Sveasoft's place to go after these guys but OTOH the violators are trying really hard to piss off Sveasoft.
Sveasoft is using the GPL in a creative, but legal way. Put this way: if you pay them for a license you get access to prerelease binaries and sourcecode. You then have a choice of licenses: you can choose to continue to follow the Seavsoft license, which will get you access to future revs of the code, or you can redistribute under the terms of the GPL which results in termination of the Seavsoft license and access to future revs.
Mark
Our mount was two 1x4" pieces of lumber. One piece was laid on the window sill, parallel to the window glass and held in place with the wood jawed clamps available at most home stores. The other piece was screwed to it sticking into the room about 1" (the depth of the dish). The dish pointed at a slight angle thru the glass.
It worked well until a tree was planted in front of the window dropping the signal strength to below functional levels with the window closed. With the tree to hide our efforts, the screen was removed and the mount flipped around with the dish outside the window. Now the dish was outside our apartment, but the management ignored it.
When I was a Dell tech a customer called in reporting they had backed over a Latitude Portable with their SUV. Not once, but 7 times. The customer stated they couldn't figure out what the bump was, so they went forward and back trying to figure it out. Good thing it wasn't their kids arm.
At another job I once had a brand new Toshiba brought to the store as non-functional. The Lysol the customer had sprayed it with failed to cover the stench of cheap beer. It had been spilled on the keyboard and removed the traces from the PC board on the bottom of the harddrive. After being presented with a $2000 repair bill on a $3000 system the customer took it back unrepaired... and I suspect he returned it to Best Buy....
Assuming that there is one AP per classroom, and connections to adjacent classrooms do not work well:
Just have the campus electrician wire the AP to a lightswitch next to the blackboard. Then the professor can make their own decision on wireless access. The user interface requires little maintainance, is easy to use and difficult to hack without getting caught or electrocuted.
Mark
Not really a fair comparison since driving style has a lot to do with fuel economy. Your buddy with the 31.5 either has a commute with much freeway driving, or has a good driving style.
For example some drivers can reach 90-100mpg in the Honda Insight. Typically this is done with nice gradual acceleration, and shifting in such a way that the electric motor is used heavily. Keep the windows rolled up, and the AC off (AC can account for 2-3mpg). Nice slow deacceleration forces the most regenerative energy to be stashed back in the batteries. (Only about the first 20% of braking force comes from the regen system,press harder on the pedal and the mechnical brakes kick in, wasting energy as heat)
Most drivers average about 40-50 mpg, and lead footed individuals can drag the Insight down to about 30mpg or less.
Driving style affects normal cars almost as much, but few people track their mileage closely. The hybrids typically have large gauges telling current fuel economy... much harder to ignore.
Also sticker mpg is based on 55mph max speed.. Aerodynamic lose increases as the square of speed.. driving 70mph instead of 55mph can make a several mpg difference as well.
Very nice, clean design overall. I'd like to know who the supplier was for the rack cases, or if they had them made custom. I've seen the half cases with the ports on the front before, but I have not been able to locate a US supplier.
It appears that the nodes are half sized, allowing for 40 systems per side, or 80 systems total. The null modem console cables connecting node pairs together is clever... if any one machine fails, you can restart it as long as its neighbor is still alive.
Mark
The parent is correct.. if worded badly.
TMI was a case of automatic safety systems being overrided by undertrained human operators. As the story paragraph mentioned, TMI was a stark lesson in control systems design.
In the control room the operators had no feedback about how much water was in the reactor core, just one gauge showing the level of water in the pressurizer tank near the top of the system. When a valve near the top of the pressurizer stuck open (referred to as the PORV or pressure operated relief value) the steam that normally kept the water near the bottom of the pressuizer tank started leaking out. More water flashes to steam.... and TMI is now losing water. The operators saw the opposite, the water level was rising on the level gauge for the pressurizer and they started reducing and eventually draining water out of the system thinking some malfunction was causing water to be introduced. None of the operators was able to step back from the initial theory that water levels were rising, despite large amounts of contradicting information. (Hours into the incident an off-duty operator arrived and with a fresh set of eyes figured out what was happening)
There are a lot more things that went wrong that night... (the initial shutdown was caused by water accidentially getting into the compressed air supply for the pneumatic control systems in the steam room, a valve closed at the wrong time and burst one of the steam lines to the power turbines)
TMI is a fascinating example of how multiple redundant systems still can fail, given a long string of "coincidences" One can argue that failures of this type are like winning the lotto, their is little chance of it happening on on particular day, but given enough days it is certain to happen to someone. Hence the need for "fail safe" designs.
I think it is apparent that the writer has little familiarity with the free/open software environment. I would not be surprised to find that many of his views were formed by reading headlines or by the arguments of the unnamed youngster.
The writer is correct from his point of view: if you are already employeed writing closed software for sale open/free software gives you no benefit. It competes for customers, and the free/open software developers do not necessarily get payment in return for their work.
The truth is a little fuzzier: most software in this world is not written for commercial sale. It is written within companies to solve particular problems in support of business processes. If no commercial alternative exists, or if an external entity cannot create a custom product then a business creates their own. Since this development is a sunk cost, sharing it, and possibility benefiting from someone else's work has no negative effects on the bottom line.
The other angle is this: as a purchaser of business software I look more favorably on open than closed software. With closed software the vendor controls me. The vendor can increase costs, withdraw support and make pretty much whatever demands he wants. With open software I have a escape clause... if my relationship with the vendor becomes negative, or I need a feature the vendor cannot/will not supply I can always take the source and find someone else to support me. If customers start demanding this option, closed vendors may not want to become open, but they may have to in order to compete. (Free/open products give control back to the consumer, a plus for the consumer, a minus for the producer)
> Pay extra for the extended warranty.
> The cost of the replacement screen was over $900.
I would still recommended buy the "damage coverage" warrenty, but it is less important than it used to be. Cracked LCDs used to cost $900, but newer laptops replacement screens can be had for $250-$400. OTOH, with laptops coming out of cases for airport screenings the number of dropped and cracked screens is definately rising.
SPF has nothing to do with banning dialup. It just allows domain owners to decide where mail should come from.
If you're sending mail direct from your dialup, odds are you have you own domain. So as the domain owner you post an SPF record that says mail from mydomain.com should only come from (insert IPs used by your diaup provider)
Now if you are sending direct and using for example aol.com in your "From:" field, your mail might get bounced (right now its more likely to be flag as possible spam), since AOL has said that want you to use their smarthost if your sending mail with a From aol.com address.
The only problem with SPF right now... no Spamassassin support.
AFAIK slashdot does not cache, but instead builds static pages from the dynamic content at regular intervals. Logged in users see a dynamic page, but most users just see the static page that is built from dynamic content
IMHO if content is not different for each user it is not really dynamic. (Plenty of sites are dynamic becuase they can be, not really becuase they should be). Even if it is mostly static with just a few dynamic elements (Like a Welcome: *username*) see if your content system supports precompiling templates or the like.
If your content changes slowly, and you're just using the db stuff to ease administration and content management, consider doing a pull from the CMS to static files.
Almost all webservers are tuned to stream data from disk to net _fast_. An apache box in a low end Pentium system can saturate a T1 pretty easily servering dynamic content. Almost all modern hardware should be able to do much more.
Another option is to speed up the database stuff... 20-30 concurrent users isn't all that much. Have you implemented connection pooling, and properly tuned your indicies for the more common queries. (Some db servers cache queries quite well). For example oracle connections can take up to 2 seconds, and an average of about 500ms to setup. If you are creating and destroying a db connection for each page request, it really slowes things down... connection pooling means only connecting to the db at first page load.
Otherwise, just use squid. It works. I would recommend setting up a linux box on some outdated piece of hardware. Yeah its not windows, but this is going to be a appliance like application. Just set and forget. You gain to added advantage that the squid/linux box will diversify your network a bit, and it protects IIS against many attacks.
I am pretty sure they are in fact D cells, just welded together and bundled into a single battery pack.
Nominal voltage of a NiMH cell is 1.2V, so that would be 120 cells. One battery site lists the weight of a single D cell at 163g, so 120 of the would be 19560g or 19.5kg.
Doing a quick google search, this article repeats my theory above, as does this one.
Its cheaper to use an already existing battery type, than to build one special for the car.
Interestingly the battery store listed above offers the Nimh D cells for $6.83 in quantities above 100. Thats $890.. and Honda currently lists the replacement cost of the Insight battery at $1500.
Yeah, your lowly little AA rechargable would happily dump 6,120A in 1 second if the short circuit had small enough resistance.
You're neglecting the fact that a battery is not a perfect voltage source. To correctly model a battery you must put a resistance in series with the voltage source, since all batteries have a internal resistance.
That having been said.. a standard D NiCd cell can put out almost 1000amps for short periods. This is why fuses and other standard short circuit protection devices were invented. Most battery packs have at least one internal fuse, larger ones will have several to handle the possibility of intra-pack shorts.
I'd love to know the Ah specification for the battery in the back seat of the Honda Hybrids. It absolutely terrifies me to know that idiots are buying them and driving around.
Then look it up.
"a total output of 144 V and 6.5 amp-hours" for the Honda Insight... about 6.0amp/hr for the Civic. The batteries themselves are Nickel Metal Hydride "D" cells.
The batteries are time bombs, hazardous waste and chemical burn nightmares.
Hazardous waste? There are far more Superfund cleanup sites caused by leaking gasoline/oil storage than battery manufacture. Lead Acid batteries are the most recycled item in the United States (more than AL cans). 95% of the battery itself can be recycled (the plastic case is often discarded. Lithium should ideally not be disposed of in the trash, but in a LiOH battery it is pretty stable. Lead Acid does offer the possibility of Acid burns, but the dilute acid is really only a problem is it gets in your eyes.. on the skin it typically only causes irration and a mild rash. And don't forget.. the explosive potential of the gasoline in your car is equal to almost 3 sticks of dynamite.
The charging process is inefficient at best (<50%).
Not sure where you get your numbers... Lead Acid batteries charging in large strings is over 90% efficent. From powerplant to road electric cars are more than twice as efficent as burning gasoline in an internal combustion engine (more than 50% of the energy in the coal burned in the powerplant ends up moving the car, as opposed to only about 11% of the energy of gasoline). Better still if you factor the environmental/energy cost of transporting, and refining the fuel (Think of the fuel it takes to run the tanker that brings the gasoline to you).
A gasoline car will always emit the same, or more pollution during its life. Most powerplants get cleaner everyday from tighter environmental resitrictions. My electric car is powered entirely from renewable energy (wind) and is more or less "zero emmission" because of it.
How many new coal and nuclear power plants are gonna have to be built when 10,000,000 Los Angeles commuters start plugging in their electric cars every night?
Most electric cars will be charged during the evening or early morning hours when demand for electricity is at its lowest. The EPA estimates that over half of the cars in California could be electric, and no additional power generation would be required. Indeed, one company showed a prototype electric car that could be used as battery when plugged in, and provide desperatly needed peaking power to avoid brownouts.
I have actually seen a video (by Valence) of a lithium ion (cobalt) battery being driven into thermal runaway... it goes off like a torch. Not something you want to have happen, but the safety systems in the batteries themselves are excellent. There have been only a handful of battery fires in the millions of currently deployed batteries.
I realize this is slashdot.. but if you want people to believe your college educated it never hurts to do some research before opening your mouth.