fsh

42 ms·

601.
by fsh 5y ago
In my experience, remote desktop solutions that use hardware accelerated encoding (Parsec, Nvidia GameStream, Steam Remote Play) are virtually indistinguishable from a local session when using wired Gigabit Ethernet. Even over the internet,
602.
by fsh 5y ago
The sweet spot would be a fissile material that can sustain a chain reaction but is not radioactive at all. Unfortunately, such an isotope does not exist. 235U and 239Pu are the next best thing.
603.
by fsh 5y ago
No, quite the opposite. Bombs and reactors use fissile materials with long half lifes, i.e. 235U (700 million years) and 239Pu (24 thousand years). Isotopes with short half lifes are very difficult to handle since they produce a lot of he
604.
by fsh 5y ago
Mourou's Nobel lecture [1] has brief explanation of the envisioned process. The idea is to use intense laser pulses to accelerate deuterium ions into a tritium target. The deuterium-tritium fusion then generates high-energy neutrons th
605.
by fsh 5y ago
These numbers are way off. Power reactors run with a few percent enrichment at most. 90% enrichment is deep in weapons territory. Reactors use slow neutrons that have thermalized in moderators. Due to the much higher fission cross section a
606.
by fsh 5y ago
No, EVs were not "totally impossible" 5 years ago. The first GM EV1s with NiMH batteries were produced 23 years ago, and the first Tesla roadsters with Li-ion batteries 14 years ago. The battery capacity and weight of the roadster
607.
by fsh 5y ago
All generated primary energy will eventually be turned into heat. However, the climate effect of this direct heating is orders of magnitude smaller than the greenhouse effect from burning hydrocarbons.
608.
by fsh 5y ago
I don't think that leakage is a serious issue in high-pressure hydrogen storage. The tanks used in hydrogen fuel cell vehicles have leakage rates of a few mL/minute [1]. The first generation Toyota Mirai has a storage capacity of
609.
by fsh 5y ago
This requires batteries which are very heavy. This is not a big problem in cars, but an absolute deal breaker in aircraft. The energy consumption of a plane scales roughly with the weight, which makes efficient battery powered flight pretty
610.
by fsh 5y ago
You are off by a factor 1000. 80 PWh is 730 billion times 110 kWh.
611.
by fsh 5y ago
Hydrocarbons are fantastic fuels when high energy density is required. In fact, airliners would be completely impossible without them. Even the most fantastic experimental batteries have nowhere near enough energy density for efficient powe
612.
by fsh 5y ago
Germany consumes the equivalent of 3300 PJ of natural gas per year, mostly for heating. This is an average heating power of 105 GW. Probably less than that in summer, and a lot more in winter. Considering how expensive nuclear power is, I d
613.
by fsh 5y ago
I don't think the computational complexity has been a significant problem for at least half a century. Aspheric lenses are described by simple polynomials and ray tracing is just elementary geometry. You only need to analyze a hand ful
614.
by fsh 5y ago
No, the colors in that schematic are only a visual aid for distinguishing the rays. Each set of colored ray bundles comes from a single object point. The task of the lens is to map them into a single point in the image plane. At the same ti
615.
by fsh 5y ago
The picture in the tweet only shows rays originating from an object that is close to the center of the field of view. The article mentioned in another comment has better schematics: https://www.pencilofrays.com/lens-design-f
616.
by fsh 5y ago
Usually some form of gradient descent is combined with a global optimization routine that tries to explore the parameter space. This is nothing new, optics has been designed this way since the early 60s.
617.
by fsh 5y ago
Neither of these websites are banned in the EU. The servers are not very responsive at the moment though. Probably someone is DDOS'ing them.
618.
by fsh 5y ago
I think he is easily one of the smartest people on YouTube and is producing some of the very best videos. He is also a brilliant educator. For examples, his videos on special [1] and general relativity [2] were real eye-openers for me, even
619.
by fsh 5y ago
A direct conversion of thermal energy into electric energy would cool down the entire system. Since electric energy carries no entropy, this would reduce the overall entropy of the system. This is forbidden by the second law of thermodynami
620.
by fsh 5y ago
I just skimmed the paper. Right in the end of the discussion, the authors write: Our model provides a rigorous demonstration that continuous thermal power can be supplied by a Brownian particle at a single temperature while in thermodynami
621.
by fsh 5y ago
All of this is correct. But I still think it is misleading to create the impression that QKD could be a replacement for RSA. Especially, since asymmetric cryptography and PKI are cornerstones of the modern internet. Why don't you chan
622.
by fsh 5y ago
The first sentence of your paper abstract is: Cryptographic key exchange protocols traditionally rely on computational conjectures such as the hardness of prime factorisation to provide security against eavesdropping attacks. Remarkably, q
623.
by fsh 5y ago
Without authentication, any form of communication is susceptible to a man-in-the-middle attack. You simply don't know who you are communicating with. This makes using QKD very hard to justify in practice. If you have exchanged a pre-
624.
by fsh 5y ago
Could you give some examples for nuclear power plants that are using a combined cycle turbine? I was under the impression that the operating temperatures of BWRs or PWRs are nowhere near high enough for that.
625.
by fsh 5y ago
Could you give a source for that? A German newspaper reports that the green party was against including gas in the taxonomy, but was overruled by the other two coalition members [1]. [1] https://www.sueddeutsche.de/politik&#
626.
by fsh 5y ago
I think you got your numbers wrong. Even in the US, you are not allowed to sell gas furnaces with less than 80% efficiency. High-end ones reach over 99% efficiency.
627.
by fsh 5y ago
You lose something like 70% of the thermal output of the reactor in the conversion to electricity. Also the capacities a nowhere near large enough. Nord Stream 2 alone can transport something like 63 GW worth of gas. This is more than the t
628.
by fsh 5y ago
This is literally the opposite of what the minister has said: https://www.bmwi.de/Redaktion/EN/Meldung/20220101-eu-taxonom... Please don't spread misinformation.
629.
by fsh 5y ago
Only 14% of the gas imported to Germany is used for electricity generation [1]. A few nuclear power plants would not make a big difference. [1] https://de.statista.com/statistik/daten/studie/37985/umfrage
630.
by fsh 5y ago
In my experience, Mathematica is probably the best software available for symbolic computations (integrals, derivatives, equation solving,...). The numerical capabilities are alright, but specialized libraries in compiled languages usually

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