Optimal Acceptance Test Plans with Grouping

This paper considers the problem of selecting an optimal acceptance test, plan. A cost model is developed which permits comparison of single, dollble, multiple, and sequential test plans. Cost elements include fixed costs to initiate testing, costs to purchase and ship components, and variable costs for testing and return or disposal of untested items.

In the case of seqllential testing, consideration of these cost factors leads to an optimization model having as decision variables the number of samples to ship to the test facility for each possible round of tests. Solution of this optimization problenl enables explicit comparison of test costs with non-sequential designs. A numerical example is provided for illtlstration.     

A cost-benefit model for production vehicle testing

In 1995 a record 17.8 million vehicles were recalled in the USA. In addition to these recalls, warranty costs for non-recallable defects, and the cost of lost future sales due to dissatisfied customers, contribute to the cost associated with poor quality. Although pre-production testing has more leverage, post-launch vehicle testing may provide valuable information in an economical fashion. By field testing the first production vehicles off the line, automotive manufacturers may detect manufacturing-related and component-interaction defects that would not be discovered by pre-production testing. We present a cost-benefit model for production vehicle field testing. Using data on defects and warranty costs for past vehicle programs, we can estimate the average warranty cost, the likelihood of a recall, the number of vehicles recalled, failure rates, and severity of defects for future vehicle programs, as well as the warranty costs avoided by a particular production vehicle test program. This cost-benefit analysis allows us to determine if a post-production vehicle test program is worthwhile, and if so, it allows us to choose the best such program.     

Availability and cost functions for periodically inspected preventively maintained units

Unavailability and cost rate functions are developed for components whose failures can occur randomly but they are detected only by periodic testing or inspections. If a failure occurs between consecutive inspections, the unit remains failed until the next inspection. Components are renewed by preventive maintenance periodically, or by repair or replacement after a failure, whichever occurs first (age-replacement). The model takes into account finite repair and maintenance durations as well as costs due to testing, repair, maintenance and lost production or accidents. For normally operating units the time-related penalty is loss of production. For standby safety equipment it is the expected cost of an accident that can happen when the component is down due to a dormant failure, repair or maintenance. The objective of maintenance optimization is to minimize the total cost rate by proper selection of two intervals, one for inspections and one for replacements. General conditions and techniques are developed for solving optimal test and maintenance intervals, with and without constraints on the production loss or accident rate. Insights are gained into how the optimal intervals depend on various cost parameters and reliability characteristics.     

低碳环境下冷链物流企业库存-配送优化

目的 优化冷链物流企业库存-配送的路径,以降低企业冷链物流的成本.方法 考虑冷链物流企业库存和配送环节产生成本的因素,并结合我国关于碳减排的碳交易政策,将企业的碳排放代价同其他代价综合考虑,建立以总代价最低为目标的成本模型,设计并改进麻雀搜索算法进行计算.结果 通过使用MatlabR2018b进行仿真实验,将采用麻雀搜索算法计算的仓储-配送作业总代价与其他经典算法进行比较,在1个仓储配送任务内,代价可减少2％～4％,验证了麻雀搜索算法解决文中代价模型的有效性.结论 该研究为冷链物流企业库存-配送优化问题提供了一种新型的解决方法,具有较强的操作性和实际意义.     

基于区块链的食品冷链质量安全信息平台构建

目的 研究区块链技术在食品安全领域,尤其是在生鲜食品冷链物流质量安全监测中的具体应用,以加强食品质量安全管理,提高食品冷链供应链效益.方法 分析生鲜食品冷链物流质量安全管理的薄弱环节,论证区块链技术的食品冷链质量安全监测适用性基础上,以区块链为底层技术构建食品冷链质量安全信息平台,研究区块链技术的创新应用对食品冷链质量安全管理的提升效果.结果 应用区块链技术构建了数据统一、运营高效的生鲜食品冷链质量安全信息平台,对食品质量安全信息进行了实时采集,实现了质量安全风险即时预警、质量安全问题有效溯源,有助于重塑食品质量安全生态系统.结论 区块链作为分布式账本、数字签名、溯源存证等一系列核心技术的组合,基于区块链技术创建食品冷链质量安全信息平台,能够强化微生物污染监测、缩短食品冷链在途时间,并使质量安全问题得到有效追踪溯源,对于加强食品质量安全管理、促进生鲜食品供应链优化有重要意义.     

基于损坏车辆分布预测与损益阈值分析下的共享单车回收研究

针对共享单车系统在运营过程中损坏车辆造成运营成本及损失愈多的情况，对损坏车辆在站点网络的分布作出预测，基于回收成本阈值分析建立损坏车辆回收网络模型，在此基础上构建以回收成本最小化为目标的回收路由指派模型，并使用禁忌搜索法与遗传算法的混合算法求解实际案例。结果表明：该方法可解决现实情境下，共享单车损坏车辆回收过程的分布预测和路径优化问题。本文的实例分析表明，建立的模型与传统回收方法相比，成本节约了8.72%，不仅降低回收过程的作业成本，同时也可以提高回收效率，对于共享单车运营商的决策优化具有一定参考价值。     

Virtual experiments,physical validation: dental morphology at the intersection of experiment and theory

Computational models such as finite-element analysis offer biologists a means of exploring the structural mechanics of biological systems that cannot be directly observed. Validated against experimental data, a model can be manipulated to perform virtual experiments, testing variables that are hard to control in physical experiments. The relationship between tooth form and the ability to break down prey is key to understanding the evolution of dentition. Recent experimental work has quantified how tooth shape promotes fracture in biological materials. We present a validated finite-element model derived from physical compression experiments. The model shows close agreement with strain patterns observed in photoelastic test materials and reaction forces measured during these experiments. We use the model to measure strain energy within the test material when different tooth shapes are used. Results show that notched blades deform materials for less strain energy cost than straight blades, giving insights into the energetic relationship between tooth form and prey materials. We identify a hypothetical ‘optimal’ blade angle that minimizes strain energy costs and test alternative prey materials via virtual experiments. Using experimental data and computational models offers an integrative approach to understand the mechanics of tooth morphology.     

孔底起爆孔网参数优化的多目标灰色决策

地下矿山中深孔爆破孔网参数优化研究对于改善爆破效果、提高铲装效率、降低采矿成本至关重要。但是影响爆破质量的因素很多，参与试验的技术经济指标缺乏公度性，加之现场试验条件和实验次数的限制，在孔底起爆孔网参数优化选择时有一定的随机性和模糊性。本文结合杨家坝铁矿具体矿岩条件，在孔底起爆孔网参数优化试验的基础上，运用多目标灰色决策理论，建立了孔网参数决策模型，从而确定了最优孔网参数。工程实践表明是合理的，并对同类矿山有一定的参考价值。     

地震模拟振动台试验模型相似设计中的材料弹性模量取值问题研究

为了提高结构地震模拟振动台试验的精度,采用实常用模型材料的力学性能试验与规范计算理论分析相结合的方式,对混凝土结构、砌体结构及钢结构地震模拟振动台试验模型相似关系设计中的材料弹性模量取值方法进行了系统研究,推荐了混凝土结构、砌体结构及钢结构地震模拟相似关系设计中材料弹性模量的合理取值方法。试验与分析结果表明：模型材料弹性模量的试验值与原型材料弹性模量的规范值可能会存在较大差异,造成模型相似关系中的模型与原型弹性模量比过小,使振动台试验结果失真。因此,当混凝土结构振动台试验模型采用微粒混凝土或砂浆材料浇筑时,模型材料与原型混凝土材料的弹性模型应统一采用规范提供的拟合公式根据材料立方体抗压强度计算得到;当砌体结构振动台试验模型采用小型混凝土砌块制作时,模型材料弹性模量应采用规范拟合公式由材料试验确定的砌体抗压强度设计值计算得到;钢结构地震模拟相似关系中的弹性模量比可采用1.0。以上结论可为不同结构地震模拟振动台试验的模型相似关系设计提供理论依据。     

Reliability-based optimization of direct and indirect LCC of RC bridge elements under coupled fatigue-corrosion deterioration processes

An optimal bridge design should minimize the life cycle cost (LCC) of the structure without compromising its safety. Various cost components need to be evaluated when assessing the life cycle cost of a reinforced concrete bridge. When the structure is subjected to performance degradation due to aging, the probabilistic modeling of degradation is required. In this paper, the reliability-based design optimization RBDO is performed on the life cycle cost of the structure subject to deterioration processes of fatigue and corrosion. This paper advances the state of the art by: considering the coupled corrosion fatigue model in the design optimization and by developing a new approach to evaluate the user delay costs on a bridge, based on direct and indirect costs related to degradation and failure. Also, a sensitivity analysis of optimal costs and design variables is performed. The improved life cycle cost analysis presented herein can be applied to select the optimal design of reinforced concrete bridge elements, by minimizing both agency and bridge user costs, while providing the required safety along the structure lifetime, taking into account the most severe degradation processes.     

Quick response procurement cost control strategy for fabric manufacturing

This paper considers a material management decision making problem with information revision of a fabric manufacturer, facing highly uncertain material supply and quick response demand. We construct a model by analysing the decision process, derive the optimal solution and study the interaction among factors through a practical data based computational simulation. The demand information, in terms of estimated volume, modifiable order, and order confirmation respectively, is provided by the final buyer to the fabric manufacturer in consecutive time periods. We investigate normal and urgent raw material (yarn) purchasing costs, holding cost, overstock salvage cost, as well as availability of raw materials for urgent order. The model for a single item is then extended to that for multiple items with the capacity constraint. The research shows that a fabric manufacturer plays a critical role in operations efficiency and overall cost control in a typical apparel supply chain, and reveals the cost trade offs between purchasing and inventory under this special business environment.     

Stress test optimization using an integrated production test and field reliability model

Numerous papers and texts have been written in the reliability literature regarding the determination of the optimum test duration for a production stress or a burn‐in test. The techniques presented have largely been based on the identification of the change point at which infant mortality has largely been removed from the units. The time‐on‐test is typically the only factor that influences this decision. Few of these models have attempted to integrate the field performance or the influence of warranty costs into this decision. This paper proposes and validates a methodology that integrates the influence of the production test failures and the field performance including their respective costs into a single unified model. The objective is to identify a production test duration that minimizes the overall cost. A Weibull model is initially developed for the production test that incorporates the failure observations in different time segments of the test based on the ability to detect latent defects in the product. A separate Weibull model is then developed for the product's performance in the field that includes the lifetime of the unit. This paper identifies how both these Weibull models can be combined into a single model including both test and field costs with the objective of minimizing the overall cost. The advantage of the proposed technique is that it does not require one to track individual units from production through to the field in order to develop an integrated test and field cost model. Copyright © 2009 John Wiley & Sons, Ltd.     

High Performance Computing in the Optimization of Software Test Plans

Statistical software testing is an increasingly popular method in the software development cycle. An exact modeling of the usage profiles of a software system is an indispensable prerequisite for statistical testing. Recently, new techniques for obtaining optimal usage profiles even the presence of rarely used critical functions have been introduced. Although these techniques deliver unbiased dependability estimates with a single model (instead of using multiple models as it is the current practice) their applicability is hampered by their prohibitive computational complexity.In this paper we demonstrate that these techniques can be effectively employed even for large software systems by exploiting high performance computing. We discuss the parallelism potential within these techniques and present a parallel implementation based on a high level parallel language—High Performance Fortran. Our techniques are general enough to allow an efficient optimization of medium to large scale test plans on high-end parallel machines as well as on more cost effective PC-clusters. A real world software system is studied in detail to prove our claims.     

水平管降膜式蒸发器的优化设计模型

对降膜式蒸发器进行热力分析建模,提供一种性能优化的数值计算方法,在模型中引入成本估算算法,用于对降膜式蒸发器的优化设计提供指导。并用样机试验结果验证该计算模型的准确性,为工程设计提供参考。     

Dynamic nanoindentation testing for studying thermally activated processes from single to nanocrystalline metals

Nanoindentation experiments are widely used for assessing the local mechanical properties of materials. In recent years some new exciting developments have been performed for also analyzing thermally activated processes using indentation based techniques. This paper focuses on how thermally activated dislocation mechanisms can be assessed by indentation strain rate jump as well as creep testing. Therefore, a small overview is given on thermally activated dislocation mechanism and how indentation data from pointed indenters can be interpreted in terms of uniaxial macroscopic testing. This requires the use of the indentation strain rate as introduced by Lucas and Oliver as well as the concepts of Taylor hardening together with Johnson expanding cavity model.These concepts are then translated to nanoindentation strain rate jump tests as well as nanoindentation long term creep test, where the control of the indenter tip movement as well as the determination of the contact are quite important for reliable data. It is furthermore discussed, that for a steady state hardness test, the interpretation of the hardness data is straightforward and comparable to macroscopic testing. For other conditions where size effects play a major role, hardness data need to be interpreted with consideration for the microstructural length scale with respect to the contact radius.Finally strain rate jump testing and long term creep testings are used to assess different thermally activated mechanisms in single to nanocrystalline metals such as: Motion of dislocation kink pairs in bcc sx-W, Grain boundary processes in nc-Ni and ufg-Al, and the Portevin-le Chatelier effect in ufg-AA6014.     

Über den Einfluss von Werkstoffkennwerten auf das Spanbruchverhalten von bleiarmem Messing

Low‐leaded brass materials are gaining in industrial significance due to multiple national and international legislative regulations. Reducing the mass fraction of lead in brass material leads to unfavorable chip forms in machining and an increased chip volume ratio, which is a measure of their bulk volume. Cutting tests show that a certain amount of reduction in lead content can be compensated by adjusting the machining parameters feed and cutting depth. A phenomenological model for the calculation of the chip volume ratio as a function of the lead content and the machining parameters is developed. This work shows that there is no significant correlation between chip volume ratio and standardized material testing procedures such as tensile test, hardness testing or quantitative microstructural analysis.     

Rapid Single-Round Pool Testing of Infectious Disease Enabled by Multicolor Digital Melting PCR

Pooled nucleic acid amplification test is a promising strategy to reduce cost and resources for screening large populations for infectious disease. However, the benefit of pooled testing is reversed when disease prevalence is high, because of the need to retest each sample to identify infected individual when a pool is positive. Split, Amplify, and Melt analysis of Pooled Assay (SAMPA) is presented, a multicolor digital melting PCR assay in nanoliter chambers that simultaneously identify infected individuals and quantify their viral loads in a single round of pooled testing. This is achieved by early sample tagging with unique barcodes and pooling, followed by single molecule barcode identification in a digital PCR platform using a highly multiplexed melt curve analysis strategy. The feasibility is demonstrated of SAMPA for quantitative unmixing and variant identification from pools of eight synthetic DNA and RNA samples corresponding to the N1 gene, as well as from heat-inactivated SARS-CoV-2 virus. Single round pooled testing of barcoded samples with SAMPA can be a valuable tool for rapid and scalable population testing of infectious disease.     

Fire resistance certification of aircraft composite materials

The Federal Aviation Administration (FAA) requires fire resistance certification of aircraft composite materials used in civil aircraft exterior structure and engine compartments. This paper presents an FAA approved process for accomplishing certification testing at minimum cost and time using an oxygen-acetylene heating tip. The test stand and process minimized human factors and quantified backside flame visibility for comparing aluminum and composite materials. The process focus was on demonstratingfire resistant characteristics, but could also be applied to thefireproof test process. Backside flame visibility was defined as the visual observance of light from the oxygen-acetylene flame. This definition was uniformly applied to both the aluminum test panels and the composite test panels. This presentation of the fire resistant certification process for aircraft composite materials will enable others to efficiently set up and perform both fire resistant and fireproof certification testing.     

A cost‐based selective maintenance decision‐making method for machining line

Machine line is a type of manufacturing system in which machines are connected in series or in parallel. It is significant to ensure the reliability as well as to reduce the total cost of maintenance and failure losses in the maintenance programs of such systems. Cost‐based selective maintenance decision‐making, which is the best method for a selected group of machines in machine line is presented under limited maintenance durations. Fault losses and maintenance costs of a single machine under different maintenance actions i.e. minimal repair, preventive maintenance and overhaul on the fault rate of the machine are calculated. An algorithm combining the heuristic rules and tabu search is proposed to solve the presented selective maintenance model. Finally, a case study on the maintenance decision‐making problem of a connecting rod machining line in the automobile engine workshop is presented to illustrate the applicability of the proposed method. The end result shows that the fault losses can be further reduced by the optimization of maintenance interval and maintenance duration. Copyright © 2010 John Wiley & Sons, Ltd.     

小尺寸试件层合板低速冲击后的剩余压缩强度

使用一种小尺寸试件试验方法来测量复合材料层合板低速冲击后的剩余压缩强度(CAI),以便减少试验费用,降低材料研制成本和周期。在试验研究的基础上,建立了复合材料低速冲击后剩余压缩强度估算的一种软化夹杂模型。该模型将冲击损伤等效成圆形低刚度的夹杂,用8节点等参元分析层合板的应力应变状态,以点应力准则为压缩破坏判据。理论分析结果与试验对比显示,该模型简单有效。