| shenaeyktq | Date: Tuesday, 25 Jun 2013, 16:54:10 | Message # 1 |
|
Colonel general
Group: Users
Messages: 973
Status: Offline
| <a href=http://www.coastclothing2.co.uk/coast-chancey-dress-red-apricot-p-21.html>Coast Chancey Dress Red Apricot</a>
<a href=http://www.coastclothing2.co.uk/red-white-coast-alva-duchess-satin-dress-p-75.html>Red White Coast Alva Duchess Satin Dress</a>
<a href=http://www.coastclothing2.co.uk/black-coast-rivington-dress-p-51.html>Black Coast Rivington Dress</a>
锘?2 September 2009
Has Catherine de Lange and those she interviewed never heard of evacuated tube transport (ETT ) ?. If ever there was a transport mode expressly designed to reduce energy but retain everything you might want from a modern transport system it is ETT. No working example yet exists, but all the required technologies are ripe enough to make a first line. The science is really simple in that air resistance is the biggest energy cost in road, rail, and air transport. Eliminate that and not only can you go faster, but you can do it much cheaper. Structurally a hollow cylinder is a stiffer structure than a flat ribbon, so compared to road and rail less material need be used for a transport route. High speed rail on the other hand is, and will remain expensive both to build and to run. Tunnels and bridges for high speed rail require to be larger than for ordinary rail to mitigate the effects of ramming air in front of the train. High speed trains and aircraft are as weather susceptible as road transport, but ETT should be largely unaffected. Once built, a well designed ETT system should be low maintenance and durable as wear and tear come mostly from friction and that will be largely eliminated. Tunneling is not so expensive these days with the modern tunnel boring machines and many of the expensive bits of road and rail ( cuttings, embankments, and bridges ) can be avoided, and even where required the above ground tubes are easier to build into spanning structures due to their superior shape. Planning permissions should be quicker and easier as there is much less impact on the landscape. Wildlife would not be involved in collisions. It would make a lot of sense to build a line between London and Birmingham with the potential to work up to speeds of approaching 500kilometers per hour.(that would give a journey time of about 27 minutes )
Using fuel cells to power vehicles is another exciting and hotly debated prospect. "A fuel cell gives us the highest efficiency device for producing electricity that we know of. It produces very low emissions too, so it's efficient and it's clean," says Nigel Brandon, director of the Energy Futures Lab at Imperial College London. Nevertheless, issues such as refuelling and ensuring the energy comes from renewable sources are proving problematic, as is the fact that fuel cells are still expensive to produce. "We need to work to make those fuel cells cheaper, and to do so we need to develop new materials," says Brandon. All these obstacles stand between fuelcell cars and the mass market. So is it a career dead end for young scientists?
What's more, we will need a whole new infrastructure to charge them think exchanging your battery when you stop at a service station rather than filling the tank. This infrastructure just doesn't exist yet. Then there is all the energy needed to run the new system: "Switching 23 million cars to electric, that requires quite a large extra chunk of electricity that we don't currently produce," says Hardy. According to Smith, these challenges are no bad thing. "If we are going to meet any of our CO2 reduction targets, there's so much for engineers to get stuck into. For anyone who enjoys a challenge, this is the most exciting time since the industrial revolution."
http://oakleysunglasses2sale.webs.com/
|
| |
|
|
