Článek se zabývá simulací napájecího systému pro trolejbusy s využitím statistického modelování pomocí metody Monte Carlo. Ověření modelu bylo provedeno na základě výsledků měření napětí a proudů v ...trolejbusovém systému v městě Gdyni. V článku je prezentován případ studie využití metody Monte Carlo pro analýzu snížení požadavku na energii v trolejbusové dopravě s využitím superkapacitorových stanic nebo změnou konfigurace napájecího systému.
The service life of railway wheels can differ significantly depending on their installed position, operating conditions, re-profiling characteristics, etc. This paper compares the wheels on two ...selected locomotives on the Iron Ore Line in northern Sweden to explore some of these differences. It proposes integrating reliability assessment data with both degradation data and re-profiling performance data. The following conclusions are drawn. First, by considering an exponential degradation path and given operation condition, the Weibull frailty model can be used to undertake reliability studies; second, among re-profiling work orders, rolling contact fatigue (RCF) is the principal reason; and third, by analysing re-profiling parameters, both the wear rate and the re-profiling loss can be monitored and investigated, a finding which could be applied in optimisation of maintenance activities.
Resurs kół pociągu może być znacząco różny w zależności od ich miejsca zamontowania, warunków pracy, charakterystyk związanych z reprofilacją, itp. W artykule, porównano koła dwóch wybranych lokomotyw kursujących na Linii Rud Żelaza w północnej Szwecji, aby zbadać niektóre ze wspomnianych różnic. Zaproponowano możliwość łączenia danych pochodzących z oceny niezawodności z danymi degradacyjnymi oraz danymi z reprofilacji. Przeprowadzone badania pozwalają wyciągnąć następujące wnioski. Po pierwsze, krzywa wykładnicza degradacji oraz zadane warunki pracy można wykorzystać w celu przeprowadzenia badań niezawodności z użyciem modelu Weibulla z efektami losowymi (tzw. "frailty model"); po drugie, główną przyczyną zlecania reprofilacji kół jest zmęczenie toczne (RCF); po trzecie, analiza parametrów reprofilacji pozwala na monitorowanie i badanie zarówno szybkości zużycia kół, jak i ubytku materiału podczas reprofilacji, co może mieć zastosowanie w optymalizacji czynności obsługowych.
Understanding Molecular Simulation: From Algorithms to Applications explains the physics behind the "recipes" of molecular simulation for materials science. Computer simulators are continuously ...confronted with questions concerning the choice of a particular technique for a given application. A wide variety of tools exist, so the choice of technique requires a good understanding of the basic principles. More importantly, such understanding may greatly improve the efficiency of a simulation program. The implementation of simulation methods is illustrated in pseudocodes and their practical use in the case studies used in the text. Since the first edition only five years ago, the simulation world has changed significantly -- current techniques have matured and new ones have appeared. This new edition deals with these new developments; in particular, there are sections on: · Transition path sampling and diffusive barrier crossing to simulaterare events · Dissipative particle dynamic as a course-grained simulation technique · Novel schemes to compute the long-ranged forces · Hamiltonian and non-Hamiltonian dynamics in the context constant-temperature and constant-pressure molecular dynamics simulations · Multiple-time step algorithms as an alternative for constraints · Defects in solids · The pruned-enriched Rosenbluth sampling, recoil-growth, and concerted rotations for complex molecules · Parallel tempering for glassy Hamiltonians Examples are included that highlight current applications and the codes of case studies are available on the World Wide Web. Several new examples have been added since the first edition to illustrate recent applications. Questions are included in this new edition. No prior knowledge of computer simulation is assumed.
The paper demonstrates the comparison of Monte Carlo simulation algorithm with neural network enhancement in the reliability case study. With regard to process dynamics, we attempt to evaluate the ...tank system unreliability related to the initiative input parameters setting. The neural network is used in equation coefficients calculation, which is executed in each transient state. Due to the neural networks, for some of the initial component settings we can achieve the results of computation faster than in classical way of coefficients calculating and substituting into the equation.
W artykule przedstawiono porównanie algorytmu symulacyjnego wykorzystującego metodę Monte Carlo względem rozszerzenia sieci neuronowych na przypadek badania niezawodności obiektów. W odniesieniu do dynamiki procesu, podjęliśmy próbę oceny niepewności (zawodności) układu zbiornika w zależności od początkowych ustawień parametrów wejściowych. Do wyznaczenia współczynników równań wykorzystywane są sieci neuronowe, a proces obliczeniowy jest wykonywany dla każdego stanu przejściowego (nieustalonego). Dzięki zastosowaniu sieci neuronowych, dla pewnych ustawień wartości początkowych jesteśmy w stanie otrzymać wyniki obliczeń szybciej, niż w przypadku zastosowania klasycznej metody wyliczenia współczynników i podstawienia ich do równania wyjściowego.
Monte Carlo methods are a class of computational algorithms for simulating the behavior of a wide range of various physical and mathematical systems (with many variables). Their utility has increased ...with general availability of fast computers, and new applications are continually forthcoming. The basic concepts of Monte Carlo are both simple and straightforward and rooted in statistics and probability theory, their defining characteristic being that the methodology relies on random or pseudo-random sequences of numbers. It is a technique of numerical analysis based on the approximate solution of a problem using repeated sampling experiments and observing the proportion of times a given property is satisfied. The term Monte Carlo was first used to describe calculational methods based on chance in the 1940s, but the methods themselves preceded the term by as much as a century. Quantum Monte Carlo (QMC) first appeared in 1982 and similarly was preceded by development of the related calculational methodology. The success of QMC methods over the past few decades has been remarkable, and this book will clearly demonstrate that success in its discussion of applications. For isolated molecules, the basic material of chemistry, QMC methods have produced exact solutions of the Schroedinger equation for very small systems and the most accurate solutions available for very large systems. The range of applications is impressive: folding of protein molecules, interactions in liquids, structure modeling in crystals and enzymes, quantum dots, designing heat shields and aerodynamic forms, architecture, design, business and economics, and even cinema and video games (3D modeling). This book takes a similar approach to Henry Schaefers classic book Quantum Chemistry (OUP, 1984 now a Dover edition), collecting summaries of some of the most important papers in the quantum Monte Carlo literature, tying everything together with analysis and discussion of applications. Quantum Monte Carlo is a reference book for quantum Monte Carlo applications, belonging near the desk of every quantum chemist, physicist, and a wide range of scientists and engineers across many disciplines, destined to become a classic.
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