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🔗 2000-Watt Society
The 2000-watt society is an environmental vision, first introduced in 1998 by the Swiss Federal Institute of Technology in Zürich (ETH Zurich), which pictures the average First World citizen reducing their overall average primary energy usage rate to no more than 2,000 watts (i.e. 2 kWh per hour or 48 kWh per day) by the year 2050, without lowering their standard of living.
The concept addresses not only personal or household energy use, but the total for the whole society, including embodied energy, divided by the population.
Two thousand watts is approximately the current world average rate of total primary energy use. This compared, in 2008, to averages of around 6,000 watts in western Europe, 12,000 watts in the United States, 1,500 watts in China, 1,000 watts in India, 500 watts in South Africa and only 300 watts in Bangladesh. Switzerland itself, then using an average of around 5,000 watts, was last a 2000-watt society in the 1960s.
It is further envisaged that the use of carbon-based fuels would be ultimately cut to no more than 500 watts per person within 50 to 100 years.
The vision was developed in response to concerns about climate change, energy security, and the future availability of energy supplies. It is supported by the Swiss Federal Office of Energy, the Association of Swiss Architects and Engineers, and other bodies.
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- "2000-Watt Society" | 2022-09-19 | 194 Upvotes 296 Comments
🔗 History of the Monte Carlo method
Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo methods are mainly used in three problem classes: optimization, numerical integration, and generating draws from a probability distribution.
In physics-related problems, Monte Carlo methods are useful for simulating systems with many coupled degrees of freedom, such as fluids, disordered materials, strongly coupled solids, and cellular structures (see cellular Potts model, interacting particle systems, McKean–Vlasov processes, kinetic models of gases).
Other examples include modeling phenomena with significant uncertainty in inputs such as the calculation of risk in business and, in mathematics, evaluation of multidimensional definite integrals with complicated boundary conditions. In application to systems engineering problems (space, oil exploration, aircraft design, etc.), Monte Carlo–based predictions of failure, cost overruns and schedule overruns are routinely better than human intuition or alternative "soft" methods.
In principle, Monte Carlo methods can be used to solve any problem having a probabilistic interpretation. By the law of large numbers, integrals described by the expected value of some random variable can be approximated by taking the empirical mean (a.k.a. the sample mean) of independent samples of the variable. When the probability distribution of the variable is parameterized, mathematicians often use a Markov chain Monte Carlo (MCMC) sampler. The central idea is to design a judicious Markov chain model with a prescribed stationary probability distribution. That is, in the limit, the samples being generated by the MCMC method will be samples from the desired (target) distribution. By the ergodic theorem, the stationary distribution is approximated by the empirical measures of the random states of the MCMC sampler.
In other problems, the objective is generating draws from a sequence of probability distributions satisfying a nonlinear evolution equation. These flows of probability distributions can always be interpreted as the distributions of the random states of a Markov process whose transition probabilities depend on the distributions of the current random states (see McKean–Vlasov processes, nonlinear filtering equation). In other instances we are given a flow of probability distributions with an increasing level of sampling complexity (path spaces models with an increasing time horizon, Boltzmann–Gibbs measures associated with decreasing temperature parameters, and many others). These models can also be seen as the evolution of the law of the random states of a nonlinear Markov chain. A natural way to simulate these sophisticated nonlinear Markov processes is to sample multiple copies of the process, replacing in the evolution equation the unknown distributions of the random states by the sampled empirical measures. In contrast with traditional Monte Carlo and MCMC methodologies, these mean-field particle techniques rely on sequential interacting samples. The terminology mean field reflects the fact that each of the samples (a.k.a. particles, individuals, walkers, agents, creatures, or phenotypes) interacts with the empirical measures of the process. When the size of the system tends to infinity, these random empirical measures converge to the deterministic distribution of the random states of the nonlinear Markov chain, so that the statistical interaction between particles vanishes.
Despite its conceptual and algorithmic simplicity, the computational cost associated with a Monte Carlo simulation can be staggeringly high. In general the method requires many samples to get a good approximation, which may incur an arbitrarily large total runtime if the processing time of a single sample is high. Although this is a severe limitation in very complex problems, the embarrassingly parallel nature of the algorithm allows this large cost to be reduced (perhaps to a feasible level) through parallel computing strategies in local processors, clusters, cloud computing, GPU, FPGA, etc.
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- "History of the Monte Carlo method" | 2022-09-18 | 94 Upvotes 26 Comments
🔗 An account of travel to the five Indian kingdoms – 723 CE
Wang ocheonchukguk jeon (Korean pronunciation: [waːŋotɕʰʌntɕʰukk͈uktɕ͈ʌn]; pinyin: wǎng wǔ tiānzhú guó zhuàn; "An account of travel to the five Indian kingdoms") is a travelogue by Buddhist monk Hyecho, who traveled from Korea to India, in the years 723 - 727/728 CE.
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- "An account of travel to the five Indian kingdoms – 723 CE" | 2022-09-17 | 113 Upvotes 17 Comments
🔗 Andrée's Arctic Balloon Expedition
Andrée's Arctic balloon expedition of 1897 was an effort to reach the North Pole in which all three Swedish expedition members – S. A. Andrée, Knut Frænkel, and Nils Strindberg – perished. Andrée, the first Swedish balloonist, proposed a voyage by hydrogen balloon from Svalbard to either Russia or Canada, which was to pass, with luck, straight over the North Pole on the way. The scheme was received with patriotic enthusiasm in Sweden, a northern nation that had fallen behind in the race for the North Pole.
Andrée ignored many early signs of the dangers associated with his balloon plan. Being able to steer the balloon to some extent was essential for a safe journey, but there was much evidence that the drag-rope steering technique he had invented was ineffective. Worse, the polar balloon Örnen (Eagle) was delivered directly to Svalbard from its manufacturer in Paris without being tested. When measurements showed it to be leaking more than expected, Andrée failed to acknowledge the risk.
After Andrée, Strindberg, and Frænkel lifted off from Svalbard in July 1897, the balloon lost hydrogen quickly and crashed on the pack ice after only two days. The explorers were unhurt but faced a grueling trek back south across the drifting icescape. Inadequately clothed, equipped, and prepared, and shocked by the difficulty of the terrain, they did not make it to safety. As the Arctic winter closed in on them in October, the group ended up exhausted on the deserted Kvitøya (White Island) in Svalbard and died there. For 33 years the fate of the expedition remained one of the unsolved riddles of the Arctic. The chance discovery in 1930 of the expedition's last camp created a media sensation in Sweden, where the dead men had been mourned and idolized.
Andrée's motives and mindset have been the subject of extensive fictional and historical discussion, particularly inspired by his apparent foolhardiness. An early example is Per Olof Sundman's fictionalized bestseller novel of 1967, The Flight of the Eagle, which portrays Andrée as weak and cynical, at the mercy of his sponsors and the media. Modern writers have been generally critical of Andrée.
Discussed on
- "Andrée's Arctic Balloon Expedition" | 2022-09-14 | 30 Upvotes 12 Comments
🔗 2022 Russian businessmen mystery deaths
The 2022 Russian businessmen mystery deaths are a series of unusual deaths of Russian-connected businessmen in 2022. Most of the deaths were officially declared to be suicides, but a number of commentators have suggested that the circumstances of the suicides appear to be suspicious and may have been staged.
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- "2022 Russian businessmen mystery deaths" | 2022-09-15 | 18 Upvotes 1 Comments
🔗 Countersteering
Countersteering is used by single-track vehicle operators, such as cyclists and motorcyclists, to initiate a turn toward a given direction by momentarily steering counter to the desired direction ("steer left to turn right"). To negotiate a turn successfully, the combined center of mass of the rider and the single-track vehicle must first be leaned in the direction of the turn, and steering briefly in the opposite direction causes that lean. The rider's action of countersteering is sometimes referred to as "giving a steering command".: 15
The scientific literature does not provide a clear and comprehensive definition of countersteering. In fact, "a proper distinction between steer torque and steer angle ... is not always made."
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- "Countersteering" | 2022-09-14 | 105 Upvotes 137 Comments
🔗 Toyota Century
The Toyota Century (Japanese: トヨタ・センチュリー, Hepburn: Toyota Senchurī) is a limousine produced mainly for the Japanese market, serving as Toyota's flagship car within Japan; globally the unrelated Lexus LS series is Toyota's flagship luxury model. Production of the Century began in 1967, and the model received only minor changes until redesigns in 1997 and 2018.
The Century derived its name from the 100th birthday of Sakichi Toyoda (born 14 February 1867), the founder of Toyota Industries. It is often used by the Imperial House of Japan, the Prime Minister of Japan, senior Japanese government leaders, and high-level executive businessmen. The Century is comparable in purpose to the Austin Princess/Daimler DS420, Cadillac Series 70, Mercedes-Benz 600 series, Chinese Red Flag, Rolls-Royce, and Russian ZIS/ZIL limousines.
The first-generation Century was available with only a V8 engine (the third post-war Japanese-built sedan so-equipped) at its introduction in 1967 until a full platform redesign in 1997. The second generation was only installed with a Toyota-designed and -built V12, an engine bespoke to the Century, until 2018, when the power-train reverted to a V8 with the addition of Toyota's hybrid technology.
While the Century is a premium, full-size luxury sedan, it is not available at Japanese Lexus dealerships; it can only be purchased at specifically identified Toyota Store locations. The gold phoenix logo used throughout is called the Hō'ō (鳳凰) or Fushichō (不死鳥) from Sinospheric mythology, representing the Imperial House of Japan, and the image can be found throughout Asia, such as the Kinkaku-ji in Kyoto.
The exterior styling of the Century has, with some modifications, remained unchanged since its introduction, primarily due to its perception as denoting conservative success. Its appearance is iconic in Asian countries and is usually painted black. The closest Japanese competitor was the Nissan President, with a similar status reputation although, during the 1960s and '70s, the high market positioning was also shared with the Mitsubishi Debonair. In the 1970s, two other Japanese competitors introduced large sedans — the Isuzu Statesman de Ville and the Mazda Roadpacer (both derived from General Motors-Australia products) — which were short-lived.
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- "Toyota Century" | 2022-09-12 | 12 Upvotes 2 Comments
🔗 Constraint Programming
Constraint programming (CP) is a paradigm for solving combinatorial problems that draws on a wide range of techniques from artificial intelligence, computer science, and operations research. In constraint programming, users declaratively state the constraints on the feasible solutions for a set of decision variables. Constraints differ from the common primitives of imperative programming languages in that they do not specify a step or sequence of steps to execute, but rather the properties of a solution to be found. In addition to constraints, users also need to specify a method to solve these constraints. This typically draws upon standard methods like chronological backtracking and constraint propagation, but may use customized code like a problem specific branching heuristic.
Constraint programming takes its root from and can be expressed in the form of constraint logic programming, which embeds constraints into a logic program. This variant of logic programming is due to Jaffar and Lassez, who extended in 1987 a specific class of constraints that were introduced in Prolog II. The first implementations of constraint logic programming were Prolog III, CLP(R), and CHIP.
Instead of logic programming, constraints can be mixed with functional programming, term rewriting, and imperative languages. Programming languages with built-in support for constraints include Oz (functional programming) and Kaleidoscope (imperative programming). Mostly, constraints are implemented in imperative languages via constraint solving toolkits, which are separate libraries for an existing imperative language.
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- "Constraint Programming" | 2022-09-11 | 125 Upvotes 58 Comments
🔗 K-219
K-219 was a Project 667A Navaga-class ballistic missile submarine (NATO reporting name Yankee I) of the Soviet Navy. It carried 16 R-27U liquid-fuel missiles powered by UDMH with nitrogen tetroxide (NTO), and equipped with either 32 or 48 nuclear warheads.K-219 was involved in what has become one of the most controversial submarine incidents during the Cold War on Friday 3 October 1986. The 15-year-old vessel, which was on an otherwise routine Cold War nuclear deterrence patrol in the North Atlantic 1,090 kilometres (680 mi) northeast of Bermuda, suffered an explosion and fire in a missile tube. While underway submerged the seal in a missile hatch cover failed, allowing high-pressure seawater to enter the missile tube and owing to the pressure differential rupture the missile fuel tanks, allowing missile's liquid fuel to mix and ultimately combust. Though there was no official announcement, the Soviet Union claimed the leak was caused by a collision with the submarine USS Augusta. Although Augusta was operating within the area, both the United States Navy and the commander of K-219, Captain Second Rank Igor Britanov, deny that a collision took place.
The incident was novelized in the book Hostile Waters, which reconstructed the incident from descriptions by the survivors, ships' logs, the official investigations, and participants both ashore and afloat from the Soviet and the American sides.
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- "K-219" | 2022-09-10 | 44 Upvotes 7 Comments
🔗 Flanderization
Flanderization is the process through which a fictional character's essential traits are exaggerated over the course of a serial work. The term flanderization was coined by TV Tropes in reference to Ned Flanders of The Simpsons, who was caricatured over the show's run from a good neighbor who was religious among other characteristics into an evangelical "bible-thumper". Flanderization has been analyzed as an aspect of serial works, especially television comedies, that shows a work's decline.
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- "Flanderization" | 2022-09-09 | 251 Upvotes 131 Comments