Differential evolution with guiding archive for global numerical optimization

Differential evolution (DE) is a simple, yet efficient, population-based global evolutionary algorithm. DE may suffer from stagnation. This study presents a DE framework with guiding archive (GAR-DE) to help DE escape from the situation of stagnation. The proposed framework constructs a guiding archive and executes stagnation detection at each iteration. Guiding archive is composed of a certain number of relatively high-quality solutions. These solutions are collected in terms of fitness as well as diversity. If a stagnated individual is detected, the proposed framework selects a solution from guiding archive to replace the base vector in mutation operator. In this way, more promising solutions are provided to guide the evolution and effectively help DE escape from the situation of stagnation. The proposed framework is applied to six original DE algorithms, as well as two advanced DE variants. Experimental results on 28 benchmark functions and 8 real-world application problems show that the proposed framework can enhance the performance of most DE algorithms studied.     

Travel Time Reliability in Vehicle Routing and Scheduling with Time Windows

This paper presents calibration of the Vehicle Routing and scheduling Problems with Time Windows-Probabilistic (VRPTW-P) model which takes into account the uncertainty of travel times. Probe vehicle data of travel times were obtained from usual operation of pickup-delivery trucks in South Osaka area. The optimal solution of the VRPTW-P model resulted in reducing total cost, running times and CO₂, NOx and Particle Materials (PM) emissions compared with the usual operation. This is attributed to better routing of VRPTW-P to choose more reliable roads. Therefore, VRPTW-P can contribute to establish efficient and environmentally friendly delivery systems in urban area.     

一种GW级3.2cm相对论返波管振荡器的数值模拟

提出了一种3.2cm的相对论返波管振荡器,并利用2.5维粒子模拟软件KARAT研究了引导磁场强度、电子能量、电子束环平均半径、电子束环厚度对输出微波的影响。最后,在电子束为环形电子束(电子束束环平均半径为0.95cm,束环厚度为1mm)、电子束束压为900kV、电子束束流为6.7kA、引导磁场为3.2T时,得到了1.2GW的微波输出。     

Computing Travel Time Reliability in Transportation Networks with Multistates and Dependent Link Failures

The measurement of transportation network travel time reliability is imperative to provide drivers with accurate route guidance information and to generate the shortest path (or alternative paths) connecting origins and destinations, especially under conditions of varying demands and limited capacities. Previous studies assumed that link failures in a road network are statistically independent and that reliability probabilities are perfectly determinable. In real life, these assumptions are dubious, because the failure of a link in one particular area does not necessarily result in the complete failure of the neighboring link, but may lead to deterioration of its performance. This paper presents a new methodology to study the multistate system reliability analysis of transportation networks for which one cannot formulate an “all or nothing” type of failure criterion and in which dependent link failures are considered. The methodology is presented, using a numerical example, for computing the probability that travel time between an origin and a destination may exceed a threshold.     

基于遗传算法的弯曲射线成像反演

介质体反演成像一直是困扰地球物理等领域的重要问题，尤其是它的计算速度、成像和稳定性等更是备受关注。首先简述了基于弯曲射线成像的基本原理，列出了反演的详细步骤，构建了用于反演的数学模型；然后提出了利用改进的遗传算法弯曲射线成像中的反演问题，并给出了改进的遗传算法步骤；最后给出了一个用改进的遗传算法成像的例子，同时为了突出该算法的优势，还把它与爬山法相比，从两者算法的本区别剖析了两者反演结果的差别，指出：正是遗传算法大规模的并行搜索以及杂交与变异的约束，导致了成像质量及速度的不同；通过它们的反演迭代运算曲线图可以看出，该算法有效地提高了成像的速度、质量和稳定性。     

Variations of Time of Concentration Estimates Using NRCS Velocity Method

Time of concentration (Tc) is the time required for runoff to travel from the hydraulically most distant point to the outlet of a watershed. The Natural Resources Conservation Service (NRCS) velocity method commonly is used to estimate Tc for hydrologic analysis and design. The NRCS velocity method applies the physical concept that travel time is a function of runoff flow length and flow velocity. Time of concentration for 96 Texas watersheds is independently estimated by three research teams using the NRCS velocity method. Drainage areas of the 96 watersheds considered in the study are approximately 0.8–440.3?km2 (0.3–170?mi2). Digital elevation models having a grid size of 30?m were used to derive watershed physical characteristics using ArcGIS or HEC-GeoHMS. Average channel width was estimated from 1?m or 1?ft digital orthoimagery quarter quadrangle or aerial photography. Each team made independent decisions to estimate parameters needed for different flow segments for the NRCS velocity method. Estimates of time of concentration made by three research teams are compared, and both graphic comparison and statistical summary demonstrate that time of concentration estimated using the NRCS velocity method is subject to large variation, dependent on the analyst-derived parameters used to estimate flow velocity. Because of the propensity for different analysts to arrive at different results, caution is required in application of the NRCS velocity method to estimate Tc.     

A perturbation method for guiding center orbit following calculations in the presence of Coulomb collisions

An orbit following guiding center Monte Carlo calculation is presented which employs a general flux coordinate system in an axisymmetric plasma equilibrium. The calculation incorporates collision effects. Furthermore, a perturbation expansion is applied for the guiding center calculations in the presence of a frictional source.     

An approximation manpower planning model for after-sales field service support

Manpower planning is a key part of after-sales field service support with a service guarantee. Accurate field travel distance approximation presents a good opportunity to lower the manpower level. By explicitly considering the uncertainties, a state-dependent travel distance approximation model is presented and used to find the optimized manpower solution. A simulation model is developed to study the relationship between staffing level, travel distance, and percentage of customers serviced on time. Numerical results show that the proposed travel distance approximation model performs much better than the classical “square root law” and other models in the literature.     

About the sense of social compatibility

The debate in the Federal Republic of Germany on the estimation of the social compatibility of the consequences of technology as a criterion for the evaluation of technical systems has been going on since the mid seventies. The approach presented discusses the normative structurally transcending perspective of the viability and developmental capacity of society. The question of desirable social development as opposed to the technically possible is raised. A criteria system for evaluating social compatibility of new information and communication technologies including AI is focused on and may serve as a consensus building forum for public technology policy discussion.     

“大昆明区”空间规划面临的机遇和挑战

本文针对昆明的发展特征及面临的挑战,引入了一种全覆盖的综合规划方法来从整体上协调空间的各种职能及保护自然潜力。对大昆明区采用基于GIS的区域模型模拟了这些政策和方法的潜在影响力。结果显示,污染减少、土地利用成本和基础设施的建设成本降低,同时城市的竞争力提高。