Domain: psi.ch
Stories and comments across the archive that link to psi.ch.
Comments · 19
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Re:Physical lies
Actually, I am an electrical engineer, I've designed many power systems, and it's quite obvious. for anyone with first year EE or physics.
First, start with a primer on air core transformers.
Then check a simple model and experiment (which confirms the model) to see what kind of coupling you can get. See slide 5 about the coupling factor.
Now learn about how coupling factor - leakage inductance - affects efficiency.
Lastly, add in the permeability of the core material - steel versus air - and it is quite obvious why an air core transformer will never be as efficient as a steel core, let alone a connector.
You don't want to believe it, fine. Physics says you're wrong. Go talk to your local EE professor and ask them if an air-core transformer, with a wide separation of misaligned coils, will be more efficient than a direct electrical wired connection. Learn for yourself.
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elog without a doubt!
I'm old school the way you are...
Site logs are a terrific means of communicating and they've saved my butt many times. I've used elog very, very successfully:
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Re:no dark matter...
Not quite..
Electric fields,
- you can easily see this with magnetic dust, like iron dust: http://people.web.psi.ch/quitmann/BarMagnet_Large.jpggravitational fields
- Can easily factor these depending on measurable bodies moving relative to each other.magnetic fields
- iron dust again.neutrinos
- it's a particle, so it can be detected: http://en.wikipedia.org/wiki/Neutrino_detectoroxygen gas, nitrogen gas, carbon dioxide
- from distant stars, easily detected by spectroscopy: http://en.wikipedia.org/wiki/Spectroscopy- But the gravitations effects which are unexplained.. those can't be explained.
Regarding the OP:
- So basically this is a fancy way of saying that empty space itself might be what's missing from the equation.. something I've believed for a very long time, but I didn't have the know-how to be able to explain it as "gravitational polarization of the quantum vacuum" - that might not be the complete answer either, as we don't know if that's enough representation of the energy which is inherent in empty space to explain what's missing, but maybe it is. -
Re:Why not?
- uranium was thought to be pretty much endless, so why do more research into thorium? (yes, U is getting in short supply now)
The uranium fuel cycle requires refinement of U235 (which also happens to be the first step to making an atomic a bomb) and leads down a path which creates weapons-grade plutonium (an alternate material for making an atomic bomb). The thorium fuel cycle does not have this problem.
- nuclear power still has the stigma of 3 Mile Island and Chernobyl attached to it. It'll be tough to get public opinion on that changed,
Measured by deaths per GW-years of electricity generated (p. 241, fig 7.2.7), nuclear power is the safest form of electricity generation man has invented. And yes, that stat includes Chernobyl. In terms of injuries per GW-years (p. 248, fig 7.3.4), nuclear is about the same as gas, oil, and hydro (coal is the safest). The public perception that nuclear power is dangerous is a myth perpetuated primarily by anti-nuclear and anti-development (mostly environmental) interests who quickly realized their main causes could be severely undercut by the establishment of nuclear power as a clean and cheap form of energy.
especially with advances in fuel cell and solar technologies
Solar is just about the worst energy-producing technology currently at our disposal. In a global survey of installed power systems, its cost per MWh (p. 122, fig 1) is roughly 10x-15x more than coal. Even wind does significantly better at 3x. Yeah it's great to dream, but solar is probably going to need another 50+ years of research and development before it's able to take over our wide-scale power generation needs economically.
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Re:2% by 2012?
Or perhaps because they do understand it? Compared to wind energy, the initial cost are twice as much, operating costs thrice as much and fuel costs infinitely more. And that was 6 years ago, wind has come down since, while nuclear remains the energy of the future...
In a global survey of energy costs (PDF warning) looking at construction, operating, and fuel costs; nuclear costs about US$31-$53 per MWh. Wind ranges from about US$45 in the US to over $140 in the Czech Republic, about $65 per Mwh overall. The U.S. figures are lower because the U.S. amortizes wind farms' construction costs over 40 years, while the rest of the world does it over 30 years. So $60/MWh is probably a more realistic figure, putting Wind at about twice the cost of Nuclear.
Oh, and besides high costs and 8-12 years of construction time, nuclear energy has to deal with safety, waste and proliferation. Somehow it's just not what investors are looking for right now.
Most of these concerns are entirely political. The huge construction time is due to excessive regulation due to (mostly) unfounded fears over nuclear power's safety. Nuclear power is the safest form of electricity generation man has invented (PDF, page 240-241). Even including Chernobyl, it has the fewest number of fatalities per GWh of electricity generated. (The most dangerous widely-used power source is actually hydro, with large numbers of fatalities associated with dam failures.) In 50+ years of commercial nuclear power generation in the U.S., there has not been a single fatality despite providing ~20% of our electricity. There have already been a few wind power maintenance-related fatalities despite their almost non-existent contribution to the power grid.
Nuclear waste is also a red herring. A 750 MW nuclear plant (about the electricity needed to power a city of a half million) produces about enough spent fuel in a year to fit in one or two bathtubs. Add in incidental irradiated material (concrete, etc) and it's about enough to fill your bathroom. That's all the waste there is for providing electricity to half a million people for a year
In comparison, a 750 MW coal plant will burn about 3-5 million tons of coal a year, producing 5-10 million tons of CO2, and releasing about 20% of the particulate matter into the atmosphere including a lot of radioactive trace elements. In fact, these trace radioactive materials contain more energy than the coal itself (that is to say, burning coal automatically produces more radioactive waste per MWh generated than nuclear). If you're truly worried about radioactive waste being released into the environment, you should be screaming for all the coal plants to be replaced by nuclear plants ASAP so at least the radioactivity is contained instead of released into the atmosphere.
Furthermore, a great deal of the spent fuel can actually be reused. Conventional nuclear plants only use about 5% of the energy contained in the fuel. The rest is treated as waste because...
Proliferation is the only real concern. Extracting the remaining ~95% of the energy from nuclear fuel thus far requires the use of breeder reactors, which unfortunately produce weapons-grade plutonium as a byproduct. There are some new reactor designs which try to minimize this (as well as an old design canceled in the 1970s).
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Re:Going fast is easy.
Yeah. Note what happens when you try to take these sort of concepts from "crazy hypercar" to "usable vehicle". Compare, for example, Pac Car II to the Aptera 2e. Same basic design philosophy, but the 2e has to be usable on city streets, hold two passengers and a good amount of cargo comfortably, be practical to mass produce, have proper acceleration and range, and in general have the amenities and safety people expect in a car. And the net result is that you go from a drag coefficient of 0.06-ish to one of 0.15-ish combined with a severalfold increase in cross-sectional area, while your weight increases from 66lbs to almost 1700lbs.
It's hard to say that Aptera wasn't going for as extreme as you can get while still meeting those basic consumer requirements; it's just that those basic consumer requirements really take a huge hit on your energy consumption. The 2e is still 2-3 times more efficient than a Prius, but it's nothing like the extreme demonstration vehicles out there such as Pac Car II.
Could you do better than the Aptera? Probably. You could go for tandem seating to reduce cross sectional area, at the expense of cargo space and some consumer acceptability. You could build out of honeycomb foam core carbon fiber rather than the equivalent using fiberglass (which is 50% denser), but that'd raise your sale price by a lot. You could skip the electric drivetrain and save a hundred pounds or two, but then you're worsening your environmental impact in other ways. So, I'm not really sure you'd want to take the concept any further than Aptera has. A lot of people already think they've gone too far...
... I should add, myself definitely *not* included; I'm on their waiting list! -
Re:NUCLEAR IS NEVER THE ANSWER
In defense of the 'nutter', nuclear power is so expensive it's not really worth investing in, unless you are planning to build some nukes.
Nuclear power is the cheapest power source, cheaper than all but the cheapest coal plants, cheaper than hydro and wind, much cheaper than solar.
Swedish power company's power generation costs
IEA survey on electricity generation costs (PDF, page 46 fig 3.10, page 57, fig 4.6 and 4.7)Nuclear is also the safest in terms of fatalities per MWh generated (yes, even including Chernobyl).
Stats on all significant power generation accidents 1969-1996 (PDF, page 240, fig 7.2.6)There are lots of other neat stats in the two PDFs, including injury rates (nuclear is about the same as hydro, only coal is safer), wind generation is much cheaper in the U.S. (maybe because the U.S. is only building it when it makes economic sense instead of where ever environmentalists want it?), solar costs almost 10x as much as other power sources
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elog
For things like this, I use elog; https://midas.psi.ch/elog/ . It's technically a logbook / blog package, but it works quite well as a simple database, storing everything in flat files easily manipulated by other tools. It provides its own web server, as well as a command-line client for automating entries.
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Re:Stand alone Wiki?It's not a wiki, per se. But you could look at Elog
It's easy to customize, and uses its own built-in http server. It's not a product you would want to use on the public Internet, but it works well for our intranet.
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Many many options
If you're doing an electromagnetics problem in 3D (I *am* a physicist specialising in this field), there are many options. This is a VERY well studied problem.
If your problem domain is not too many wavelengths big (i.e. near-field), you want a FDTD solver. There are many commercial packages available but most are expensive (just google for FDTD). FDTD is quite simple in concept but there are various details to get right to make a general purpose solver (e.g. boundary conditions). There are a number of hardware-based solvers on the market utilising GPUs for electromagnetics calculations. If you only need a single-frequency (eigenmode) solution, then Finite Element Method might be for you (e.g. see http://people.web.psi.ch/geus/pyfemax/). If you have extreme aspect ratios you need to model (i.e. interaction between widely spaced components), then the Boundary Element Method might suit (but it's harder to understand and implement).
If you're rolling your own solution, Python makes an excellent "glue language" to tie solvers together and visualise results with VTK (www.vtk.org) and add configuration GUIs. -
I prefer the Zinc method
You can use solar furnaces to decompose Zinc Oxide into Zinc. You can then use Zinc instead of aluminium to create your hydrogen. The reason people are excited about methods like this is that hydrogen is hard to transport. If you can ship around big blocks of zinc, then add water to get your hydrogen.
Paul Scherrer Institute
You can even just use zinc in a zinc-air fuel cell
Zinc-Air Battery
Or you can use Sodium Borohydride
Sodium Borohydride -
Try elogd
Definately give elogd a spin. Customized inputs. security, self-contained web server, xml exports, simple configuration, very quick, searching, yada yada. I used it for a few years for ticket tracking when I had a smaller number of customers. Worked like a charm. See it here: http://midas.psi.ch/elog/index.html.
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needs to be carefully managed
I work on an experiment located at one of the world's highest intensity cyclotrons, at the Paul Scherrer Institute in Switzerland. It has a proton beam current of almost 2 milliamps. The radiation protection issues there are quite serious, and are carefully managed. This kind of activity needs to take place within a regulatory framework, not in some guy's backyard.
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Re:FP BS!
I recently happened to read an article on the Swiss Paul Scherer Institute that mostly developed the Zinc/solar technology. They have also conducted lots of other research into solar energy applications. The Weizmann Institute seems to primarily be a convenient high-tech location with lots of sunshine to place a test facility at, since Switzerland is not exactly blessed with high incidence of solar energy.
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Re:FP BS!
I recently happened to read an article on the Swiss Paul Scherer Institute that mostly developed the Zinc/solar technology. They have also conducted lots of other research into solar energy applications. The Weizmann Institute seems to primarily be a convenient high-tech location with lots of sunshine to place a test facility at, since Switzerland is not exactly blessed with high incidence of solar energy.
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Re:Got a Mac?
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elogTry out elog.
It's a simple web-based logging system (single stand-alone executable availabile for *nix or windoze) that you can get running in just a few minutes. We use it for tracking issues with vendors, entering changes to machines, etc.
It's free and the opportunity cost is only an hour or so. It won't do everything but it will probably meet your needs and you can impress your coworkers by having it up and running by the end of the day.
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Re:Old Fashioned Notebooks
Paper notebooks are great but only really useful for the notbook owner. Also they are not searchable. That's why, in addition to Twiki, we use the wonderful Elog program.
It is completely standalone (has its own web server built in) and is super-simple to configure. A great tool for tracking things like configuration changes on machines.
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Re:Physics Analysis Workstation.I've used PAW quite a bit for my work. It's quite effective at stuff, but the documentation is abyssmal. I found it really really painful to learn, and as a result I didn't get very far into it.
Something almost as hard to learn but somewhat easier to actually use is Physica, developed at TRIUMF. It's the main program I used to do my M.Sc. analysis work.
:)For data aquisition (and generally running an experiment), I strongly suggest looking into MIDAS. It's really powerful, and has a web interface (with optional password protection), electronic log book, etc, which is really helpful for experimenters to keep tabs on things from home. Especially when "home" is in another city (or even country).