时间和损失不确定的军械紧急调运决策优化

由于自然环境、敌方打击破坏等因素的影响,战时军械紧急调运必然存在着一定的不确定性。为了使决策具有更大实用价值,在决策时必须考虑这种实际调运过程中存在的不确定性。然而,已有的军械调运模型均未考虑这种不确定性,无法适用于时间和损失不确定的调运决策优化。针对这一不足,在已有模型的基础上,建立了一种基于仿真的军械调运决策模型。模型中考虑了军械调运中存在的不确定性,能够适用于时间和损失不确定的调运决策优化。最后通过算例,说明了模型的有效性。

基于信息共享的发动机再制造业务流程再造优化

回收与订单需求之间的不匹配是发动机再制造业务供应链上的主要不确定因素,且给柴油发动机再制造商A在库存管理和提高订单满足率上带来困难。根据现代供应链管理和产品全生命周期理论,信息共享对于减轻不确定性因素的影响来说至关重要。在回收废旧发动机机型和质量状态、零件仓库库存及缺料订单等信息共享的前提下,针对企业A原有业务流程提出了优化再造方案,并使用离散事件仿真软件Extendsim对优化前后业务流程进行仿真。仿真结果的对比显示基于信息共享的优化业务流程在性能表现上有显著提升,能很好的改善企业A在库存管理和订单满足率上存在的问题。

Effect of quality uncertainty of parts on performance of reprocessing system in remanufacturing environment

Aimed at the problem of stochastic routings for reprocessing operations and highly variable processing times,an open queuing network is utilized to model a typical reprocessing system.In the model,each server is subject to breakdown and has a finite buffer capacity,while repair times,breakdown times and service time follow an exponential distribution.Based on the decomposition principle and the expansion methodology,an approximation analytical algorithm is proposed to calculate the mean reprocessing time,the throughput of each server and other parameters of the processing system.Then an approach to determining the quality of disassembled parts is suggested,on the basis of which the effect of parts quality on the performance of the reprocessing system is investigated.Numerical examples show that there is a negative correlation between quality of parts and their mean reprocessing time.Furthermore,marginal reprocessing time of the parts decrease with the drop in their quality.

Performance of bottleneck shifting for remanufacturing system considering returns' quality grading

Aimed at the remanufacturing system, the effect of the uncertainty of returns＇ quality on bottleneck shifting is investigated. A novel definition of bottleneck station is presented and the probability of a station becoming a bottleneck is also given. By calculating the effective output, the effective operation time （EOT） and the ratio of EOT of each station, the system＇s current bottleneck of effective output time is determined. By calculating the probability coefficient of variation and index of bottleneck shifting, the quantitative performance of bottleneck shifting is obtained. Discrete event simulation and the experiment design method are adopted to simulate the system, in which the proportion of quality grading, repair rates and process routes are considered. The case study shows that the uncertainty of returns＇ quality greatly increases the probability of bottleneck shifting, and with the increase of the discrete degree of the returns＇ repair rate, the bottleneck shifting phenomenon is more obvious. Furthermore, bottleneck shifting is closely related to the process route of the dominating returns＇ quality grade.

Discussion on Repeatability and Reproducibility of Measuring Method in ISO 5725

This paper discusses the repeatability and reproducibility of the international standard of ISO 5725：1994 Accuracy （trueness and precision） of Measurement Methods and Results, two concepts of ＂inter-laboratory variance＂ and ＂reproducible variance＂ in the standard are questioned, the corresponding improvement idea is introduced, which aims to make this standard more rigorous, scientific and logical.

Urbanization-related warming in local temperature records:a review

There have long been arguments about the impact of urbanization on local meteorological observations. This letter reviews up-to-date studies of the urbanization-related warming in the observed land surface air temperature series in China. Many previous studies have suggested that, over the past few decades, the local warming due to urbanization could have been about 0.1 °C/10 yr, or even larger. However, based on recently developed homogenized temperature records, the estimated urban bias is smaller. Major uncertainties arise from either the data quality or the techniques used to estimate the urbanization effect. A key example is the ‘observationminus-reanalysis＇ method, which tends to overestimate the urban signal in this region, partly due to systematic bias in the multi-decadal variability of surface air temperature in the reanalysis data. It is expected that improved numerical modeling with high-resolution information regarding the changing land surface in the region will help to further understand and quantify the effect of urbanization in local temperature records.

Multi-objective planning model for simultaneous reconfiguration of power distribution network and allocation of renewable energy resources and capacitors with considering uncertainties

This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously and to improve power system's accountability and system performance parameters. Due to finding solution which is closer to realistic characteristics, load forecasting, market price errors and the uncertainties related to the variable output power of wind based DG units are put in consideration. This work employs NSGA-II accompanied by the fuzzy set theory to solve the aforementioned multi-objective problem. The proposed scheme finally leads to a solution with a minimum voltage deviation, a maximum voltage stability, lower amount of pollutant and lower cost. The cost includes the installation costs of new equipment, reconfiguration costs, power loss cost, reliability cost, cost of energy purchased from power market, upgrade costs of lines and operation and maintenance costs of DGs. Therefore, the proposed methodology improves power quality, reliability and security in lower costs besides its preserve, with the operational indices of power distribution networks in acceptable level. To validate the proposed methodology's usefulness, it was applied on the IEEE 33-bus distribution system then the outcomes were compared with initial configuration.