Collaborative optimization of maintenance and spare ordering of continuously degrading systems

A collaborative optimization model for maintenance and spare ordering of a single-unit degrading system is proposed in this paper based on the continuous detection. A gamma distribution is used to model the material degradation. The degrading decrement after the imperfect maintenance action is assumed as a random variable normal distribution. This model aims to obtain the optimal maintenance policy and spare ordering point with the expected cost rate within system lifecycle as the optimization objective. The rationality and feasibility of the model are proved through a numerical example.     

Optimum design of equivalent accelerated life testing plans based on proportional hazards-proportional odds model

The optimum design of equivalent accelerated life testing plan based on proportional hazards-proportional odds model using D-optimality is presented.The defined equivalent test plan is the test plan that has the same value of the determinant of Fisher information matrix.The equivalent test plan of step stress accelerated life testing(SSALT) to a baseline optimum constant stress accelerated life testing(CSALT) plan is obtained by adjusting the censoring time of SSALT and solving the optimization problem for each case to achieve the same value of the determinant of Fisher information matrix as in the baseline optimum CSALT plan.Numerical examples are given finally which demonstrate the equivalent SSALT plan to the baseline optimum CSALT plan reduces almost half of the test time while achieving approximately the same estimation errors of model parameters.     

Inspection interval optimization for aircraft composite structures with dent and delamination damage

The optimization of inspection intervals for composite structures has been proposed,but only one damage type,dent damage,has been addressed so far.The present study focuses on the two main damage types of dent and delamination,and a model for optimizing the inspection interval of composite structures is proposed to minimize the total maintenance cost on the premise that the probability of structure failure will not exceed the acceptable level.In order to analyze the damage characteristics and the residual strength of the composite structure,the frequency,energy,size,and depth of the damage are studied,and the situation of missing detection during the inspection is considered.The structural residual strength and total maintenance cost are quantified corresponding to different inspection intervals.The proposed optimization method relieves the constraints in previous simulation methods,and is more consistent with the actual situation.Finally,the outer wing of aircraft is taken as an example,and with the historical cases and experimental data,the optimization method is verified.The optimal inspection interval is shorter than the actually implemented inspection interval,and the corresponding maintenance cost is reduced by 23.3%.The result shows the feasibility and effectiveness of the proposed optimization method.     

Optimization of dynamic sequential test strategy for equipment health management

Testing is the premise and foundation of realizing equipment health management (EHM). To address the problem that the static periodic test strategy may cause deficient test or excessive test, a dynamic sequential test strategy (DSTS) for EHM is presented. Considering the situation that equipment health state is not completely observable in reality, a DSTS optimization method based on partially observable semi-Markov decision process (POSMDP) is proposed. Firstly, an equipment health state degradation model is constructed by Markov process, and the control limit maintenance policy is also introduced. Secondly, POSMDP is formulated in great detail. And then, POSMDP is converted to completely observable belief semi-Markov decision process (BSMDP) through belief state. The optimal equation and the corresponding optimal DSTS, which minimize the long-run expected average cost per unit time, are obtained with BSMDP. The results of application in complex equipment show that the proposed DSTS is feasible and effective.     

UNDERSTANDING OF FUZZY OPTIMIZATION： THEORIES AND METHODS

A brief summary on and comprehensive understanding of fuzzy optimizationis presented. This summary is made on aspects of fuzzy modelling and fuzzy optimization,classification and formulation for the fuzzy optimization problems, models and methods.The importance of interpretation of the problem and formulation of the optimal solutionin fuzzy sense are emphasized in the summary of the fuzzy optimization.     

NOVEL MULTI—LEVEL OPTIMIZATION METHOD FOR CHEMICAL COMPLEX USING INTELLIGENT AGENT

Multi-level optimization of complex chemical complex was comprehensively analyzed, includingthe optimization of management plan, production scheme, operating conditions, etc. The softwareframework of multi-level optimization of chemical complex was worked out. Basing upon the frame ofmulti-level optimization, the intelligent agent technique was adopted to search for global optimum.The organization, function, design and the implementation of a series of intelligent agents werediscussed. According to the strategy that to spend most computing time in optimization solving andmuch less time in exchanging information regarding the tasks and results of optimization throughnetwork, the communication mechanism and cooperation rules for Multi-Agent System forhierarchically optimizing chemical complex was proposed.     

多机编队队形控制建模及可视化仿真系统设计

针对多机协同作战编队队形控制问题,给出了相应的军事概念模型,提出了基于几何约束的三角形、菱形、主从式等典型树形编队控制模型,并通过可视化仿真技术,构建了可用于制定试飞方案的可视化仿真验证环境。验证结果表明基于该编队队形控制的算法可用于简单的模拟飞行操作和战术对抗、验证飞机模型。

Abstract：

In order to control the form of multi-fighters cooperative combat in formation, the military notion model was introduced. Several typical tree form team models （triangle, lozenge and leader-follower） based on geometry constraint were proposed on multi-fighters flying in formation. Through researching VR technology, a visual simulation testing model platform was built for making a plan of flight-testing mission. The simulation results indicate that the arithmetic can be well used on simulating flight, anti-tactics and valuating the flight models.     

System of developing scale modeling and simulation for URAV

The unmanned reconnaissance aerial vehicle （URAV） plays an important role in battlefield monitoring and information acquiring because of its advantage of zero casualties, and has thus attracted considerable attention of the world. The URAV was developed rapidly in our country, however, no scientific assessment methods have yet been provided owing to different fight requirements of armed forces. Considering the demand of the missile artillery on the martial information, the model of information requirement of combat force, the reconnaissance ability of URAV, the survivability of URAV, and the task reliability of URAV were constructed, respectively. By synthesizing the mathematic models above, the model of developing demand was constructed on the URAV equipment. It simulated and calculated some URAV equipment developing scales, and explored a way of settling the problem of URAV equipment developing demand.     

基于Extend与HLA的装备保障仿真集成研究

分析了Extend应用于装备保障仿真的不足,在讨论基于HLA的装备保障仿真系统的基础上,提出了Extend与HLA/RTI的四种仿真集成方式,依据Extend模型是否需要与HLA/RTI进行时间同步分别给出了集成方法,设计了基于适配器的Extend与HLA集成框架,详细说明了适配器的组成功能及工作流程,最后利用一个装备保障仿真系统应用实例证明了仿真集成的思路是可行的和必要的。

Abstract：

Because of the shortages of Extend software applied to equipment support simulation,four integration types between Extend and HLA were proposed about the building of equipment support simulation system based on HLA.According to whether Extend simulation model was synchronous to HLA/RTI on the mechanism of advance simulation time,the methods were respectively put forward to support these types,and an integration architecture between Extend and HLA was designed based on a general adaptor.The components and functions of this adaptor,and its running mechanism were detailedly analyzed later.Finally,an application of a simulation system proves that the idea to integrate the two platforms is feasible.     

单线列车运行调整的梯度搜索算法仿真与研究

列车运行调整的优化是一个非常复杂的问题,需考虑的因素很多,很难给出一个完美的优化模型。根据单线列车运行调整的特点,建立了单线列车运行图的离散事件拓扑图模型,提出了＂调整运行图综合满意度＂作为运行调整的目标,并进一步论证了＂调整运行图综合满意度＂函数的单调递减特性;提出了冲突树的概念和梯度搜索算法的算法原理及搜索步骤,并实例进行仿真。仿真结果表明,该算法模型在实际运行过程中的具有较好的优化性和有效性。

Abstract：

The optimization of railway rescheduling is a very complex issue, many factors should to be taken into account, and it’s difficult to give a perfect optimization model. A discrete event topologic diagram model was derived according to the characteristics of the single-track railway diagram, and the ＂comprehensive satisfaction of the adjusted train diagram＂ was proposed as the target of the railway rescheduling, then the monotonically decreasing characteristic of the target function was demonstrated. The concept of conflict tree was developed and the principle and steps of the gradient search algorithm based on the DET model were given and simulated. The simulation results show that this algorithm has better adaptability and effectiveness in practical application.     

面向任务的舰船编队保障模式及备件配置研究

备品备件是装备计划修理、临时修理和战场应急抢修的重要保障物资，对装备保障能力的及时形成和长久保持发挥重要作用.针对海上任务期间，舰船编队自主保障和伴随保障两种典型保障模式，以编队携行能力（总体积）为约束，装备可用度为目标函数，建立了备件配置优化模型.在相同的装备可用度指标约束下，对两种保障模式在不同维修能力下的备件配置优化方案进行了对比和分析，并采用蒙特卡罗仿真模型对计算结果进行了验证.案例结果表明：相比自主保障而言，伴随保障模式下的编队备件资源具有更高的利用率，仿真结果与解析结果误差小于4%，进一步验证了模型的正确性和可行性，研究结果能够为海上编队任务期间制定合理的保障模式和优化备件携行方案提供决策支持.     

具备有限维修能力的舰船编队保障方案优化

以舰船编队维修保障资源优化为研究背景,在VARI-METRIC理论基础上,拓展了“无限维修总体”的假设条件,根据M/M/c排队论,建立了有限维修能力约束下的舰船装备可用度评估模型。以保障费用为优化目标,在装备可用度指标约束下,采用边际优化算法,对出航前舰船编队维修保障资源进行综合优化。通过任务想定,给出了优化结果,并对其进行了分析,结果较为合理。研究结论能够为装备保障管理人员制定保障方案提供决策支持。     

无维护下极低使用占空比装备贮存使用阶段备件配置优化

针对当前舰艇装备备件配置均按常用装备、未考虑极低使用占空比装备不工作期间失效的不合理情况,对极低使用占空比装备不使用期间因部件故障对任务期间备件配置影响展开了研究。通过引入虚拟站点,将装备不使用期间等效转换为装备使用期间的状态,以装备可靠度为指标,建立了任务期间装备贮存使用的可靠度模型。以装备可靠度为约束,基于边际优化算法建立了舰艇装备备件配置优化模型;并依据备件保障流程,基于蒙特卡罗方法搭建了仿真模型。通过案例分析可知:对于极低使用占空比装备,考虑装备不使用期间部件失效的备件比不考虑装备贮存失效的备件要多,且模型的正确性通过仿真方法得到验证。模型可为舰艇上极少使用、长期贮存的装备制定备件方案提供参考。     

考虑期望体系效能衰减的舰艇编队等级修理计划优化

舰艇编队等级修理计划优化直接关系到各类战训任务的有效完成和修理经费的科学使用。基于“定期与'双控’相结合”修理模式, 考虑舰艇编队的体系化运用、舰艇效能衰减特性以及决策者期望和偏好, 运用前景理论综合构建舰艇编队期望体系效能模型, 进而以体系效能价值函数最大为目标, 以修理工期、跨期修理、修理经费、装备效能、在航率等为约束条件, 系统构建面向舰艇编队的等级修理计划优化模型, 最后运用基于混合编码的粒子群优化算法对模型进行求解。结果表明, 该方法相对传统的计划编制方法, 舰艇编队体系效能和分项效能更高, 舰艇使用与修理之间的关系协调更好, 对于科学编制舰艇编队等级修理计划, 确保舰艇编队战训任务有效完成能够提供有力的技术支撑。     

合成部队多阶段作战任务成功概率仿真评估

考虑战场环境和战时装备维修保障评估合成部队多阶段作战任务成功概率, 对于辅助合成部队作战任务规划和装备维修保障决策具有重要的现实意义。在分析合成部队装备和合成部队装备维修保障模式的基础上, 构建了战时合成部队多阶段任务剖面; 通过对合成部队作战过程的分析, 提出了战时合成部队各阶段任务成功要求; 充分考虑合成部队多作战单元任务的协同性、合成部队装备的多样性及其战时随机共因失效(random common cause failure, RCCF)、战场环境下敌方火力打击和阶段任务时间的随机性、换件修理时间的不确定性等复杂因素, 利用蒙特卡罗仿真(Monte Carlo simulation, MCS)原理给出了合成部队多阶段作战任务成功概率评估的详细仿真流程, 并通过算例进行仿真和结果分析。研究结果表明:本文模型可用于合成部队多阶段作战任务成功概率评估和战斗阶段持续时间优化, 并为战时合成部队备件携行方案优化奠定了模型基础。     

面向多阶段任务可用度的装备群维修决策模型

多种维修方式的综合应用可最大限度提高装备可用度。针对装备群的多阶段任务特点,将维修活动近似安排在任务间隔期内,认为部件以一定的概率必然出现故障,获得了阶段期望维修时间。然后充分考虑了部件的3种维修策略以及产生的延误时间,给出了任务可用度的定义。以最大化任务可用度为目的,在综合分析阶段任务分配方案及维修方式选择影响的基础上,建立了一种非线性整数规划模型。基于问题实际提出了改进遗传算法对模型进行求解,以新的多层分段染色体形式表示优化方案,并调整遗传算子的操作方法以易于算法的实现。最后给出具体实例证明了模型及算法的有效性,有利于决策人员做出合理的任务及维修活动安排。     

资源约束的拼件维修模型与粒子群求解算法

为了获得最优的装备作战单元的拼件维修方案与任务分配方案, 建立了一种同时优化拼件维修方案与任务分配方案的非线性规划模型, 模型中同时考虑了不同任务对武器系统的具体需求、武器系统的客观情况、维修资源约束, 可以最大化地协调任务、装备群与维修资源之间的矛盾, 所以更加贴合实际. 设计了基于粒子群算法的求解算法, 包括算法框架、粒子的表示、初始化、适应度函数、更新方法等. 最后, 应用该粒子群算法对具体实例进行了求解, 分析表明模型与算法可以有效地优化任务分配方案与拼件维修方案, 提高装备作战单元任务成功概率, 为决策者制定决策提供指导.     

基于任务可靠性的多阶段系统设备投入策略优化模型

为保证多阶段任务系统的高可靠性,在执行各阶段任务的过程中不仅会设置设备备份,同时也会设置复杂的任务执行方案备份.本文通过研究多阶段系统在各阶段的可执行任务状态空间、状态转移关系以及各阶段之间的状态影射关系,构建了该类系统的Markov可靠性模型.并以各阶段初的设备投入策略作为决策变量,系统的任务可靠性作为优化目标,设备投入工时作为约束条件构建了多阶段系统的设备投入策略优化模型.算例分析表明,本文模型利于对多阶段系统开展可靠性分析与系统的设备投入策略分析.     

有限任务间隔时间内的装备选择性维修决策研究

在序贯任务过程中,在有限任务间隔时间约束条件下,以提高装备的任务可靠度为目标,建立了复杂串并联系统任务可靠度模型,以最小维修、预防更换和事后更换为可选维修策略,建立了总维修时间约束条件下以任务可靠度最大化为目标的选择性维修决策模型。采用遗传算法建立了选择性维修决策优化求解算法,解决了求解空间爆炸问题。案例分析表明,装备选择性维修决策模型及基于遗传算法的优化求解方法是有效的。     

装备保障对象系统任务持续性模型研究

任务持续性是装备保障对象系统在规定的任务时间内和规定的保障条件下能够连续执行训练和作战任务的能力,评估保障对象系统的任务持续性对于评估装备保障系统的保障能力具有重要意义。选取任务可靠度作为装备保障对象系统的任务持续性评估参数,研究了装备保障对象分别为装备、基本作战单元和作战单元时任务可靠度的建模方法,建立了考虑维修保障和备件补充的不同层次装备保障对象系统的任务可靠度模型。算例分析表明了该模型的实用性和有效性。