查看更多>>摘要：There are many approaches to solving a system of interval linear equations. Each of them has different semantics based on the context of the system. We define here two other types of solutions called 'tolerance-localized' and 'control-localized' solutions. A tolerance localized solution means that it provides either tolerance, L-localized, or R-localized behavior in each equation of the system. The similar argument serves for a control-localized solution. Theorems are proved to obtain the characterizations of the new solutions. Both sets of tolerance-localized and control-localized solutions could be represented by a system of integer linear equations. An example of application to the course assignment problem is presented, where the teaching workload restriction has been considered as tolerance localized or control-localized constraints.(c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：The spherical Couette flow (SCF) system with the flow between two concentric rotating spheres is one of the most convenient example in exploring the laminar-turbulent transition. The transitions occurred in this flow phenomena has a great relevance with the geophysical motions and has applications in hydrodynamic problems. In the present work, we numerically study different flow instabilities in a narrow-gap SCF between two concentric spheres with only inner sphere rotating and the outer sphere is fixed. The time dependent three-dimensional incompressible Navier-Stokes equations (INSEs) along with a parallelized line Gauss-Seidel(LGS) solver has been used for the simulation of different flow instabilities in a narrow-gap clearance ratios(CR), beta= (R-2 - R-1)/R-1 = 0.10. The flow instabilities have been investigated for a range of Reynolds numbers (Re) 170 <= Re <= 1200 0. For this narrow-gap CR, first we obtain the 0-,1-,2-,3-, and 4-vortex flows at Re = 1430, 1440, 1460, 1750 and 1950 respectively by using the Stokes flow (SF) as an initial condition. Further increasing the Re using the same initial condition the flow becomes wavy, spiral wavy, then return back to supercritical basic flow and finally becomes turbulent at higher Re. The computed numerical results have a good agreement with the existing numerical and experimental results. Further more, we have noticed some new flow states which have not been observed in the previous numerical and experimental studies. (C) 2022 Elsevier Inc. All rights reserved.
Wagner, MichaelColbourn, Charles J.Simos, Dimitris E.
21页
查看更多>>摘要：Combinatorial testing makes it possible to test large systems effectively while maintaining certain coverage guarantees. At the same time, the construction of optimized covering arrays (CAs) with a large number of columns is a challenging task. Heuristic and Meta heuristic approaches often become inefficient when applied to large instances, as the computation of the quality for new moves or solutions during the search becomes too slow. Recently, the generation of covering perfect hash families (CPHFs) has led to vast improvements to the state of the art for many different instances of covering arrays. CPHFs can be considered a compact form of a specific family of covering arrays. Their compact representation makes it possible to apply heuristic methods for instances with a much larger number of columns. In this work, we adapt the ideas of the well-known In-Parameter-Order (IPO) strategy for covering array generation to efficiently construct CPHFs, and therefore implicitly covering arrays. We design a way to realize the concept of vertical extension steps in the context of CPHFs and discuss how a horizontal extension can be implemented in an efficient manner. Further, we develop a horizontal extension strategy for CPHFs with subspace restrictions that identifies candidate columns greedily based on conditional expectation. Then using a local optimization strategy, a candidate may be adjoined to the solution or may replace one of the existing columns. An extensive set of computational results yields many significant improvements on the sizes of the smallest known covering arrays.(c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Switching strategy is generally accompanied by material cost or mental pressure to players in reality. An efficient solution is to hold the current strategy for a period time before the next updating. In evolutionary games, it has been reported that strategy persistence or strategy inertia could promote cooperation. There arises a question that how players determine the duration of their strategy persistence time, which is also called the persistence level. Here, we consider the evolutionary prisoner's dilemma games in which players can adapt their persistence levels based on the comparison between the local and global environments. We assume that, the players who have better local environments tend to preserve their current strategies longer and increase the persistence levels. In contrast, those whose local environments are worse than the global environment tend to decrease their persistence levels. The results show that network reciprocity can get greatly enhanced by such an adaptive strategy persistence, especially in hostile environments to cooperation. Moreover, by comparing with the fixed and randomly adaptive persistence level cases, we emphasize the importance of the environment comparison in enlarging the persistence levels of cooperators, which could be further enhanced by a larger upper limit or a smaller increment of persistence level. Our results provide insights into the promotion of cooperation by the adaptive strategy persistence when players can perceive both the local and global environments in evolutionary games. (C) 2022 Elsevier Inc. All rights reserved.
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Elsevier