A Dynamic Maintenance Strategy for Multi-Component Systems Using a Genetic Algorithm

In multi-component systems,the components are dependent,rather than degenerating independently,leading to changes inmaintenance schedules.In this situation,this study proposes a grouping dynamicmaintenance strategy.Considering the structure of multi-component systems,the maintenance strategy is determined according to the importance of the components.The strategy can minimize the expected depreciation cost of the system and divide the system into optimal groups that meet economic requirements.First,multi-component models are grouped.Then,a failure probability model of multi-component systems is established.The maintenance parameters in each maintenance cycle are updated according to the failure probability of the components.Second,the component importance indicator is introduced into the grouping model,and the optimization model,which aimed at a maximum economic profit,is established.A genetic algorithm is used to solve the non-deterministic polynomial(NP)-complete problem in the optimization model,and the optimal grouping is obtained through the initial grouping determined by random allocation.An 11-component series and parallel system is used to illustrate the effectiveness of the proposed strategy,and the influence of the system structure and the parameters on the maintenance strategy is discussed.

A New Method to Optimize the Maintenance Strategy of HVDC Transmission System

A method based on fuzzy comprehensive evaluation to optimize the maintenance strategy of HVDC transmission system is proposed to provide quantitative reference for the maintenance arrangements. Firstly, a system based on fuzzy comprehensive evaluation, is established to fuzzy the index results of power system adequacy evaluation, so as to analysis the degree of risk in the operation of power system and the effect brought by the maintenance of HVDC. Then, the proposal on the maintenance of HVDC can be formed through the quantization and evaluation summary of the fuzzy results. The equivalent network of the China Southern Power Grid in 2011 ,which respectively operates in the circumstances of peak load, general load and low load, demonstrates the HVDC transmission systems in different operation modes have corresponding Overhaul timing .The result shows that the method proposed is valid and in accordance with engineering practice.

Ship System Maintenance Strategy Selection Based on DELPHI-AHP-TOPSIS Methodology

Maintenance decision problems generally involve multiple criteria which apparently are best addressed using Multi-Criteria Decision Making (MCDM) tools. This paper describes the use of a hybrid MCDM technique in prioritizing maintenance strategy for ship systems. The Hybrid MCDM technique combines Delphi method, AHP and TOPSIS methods. While the Delphi method and AHP are applied in screening of decision criteria and decision criteria weights determination respectively, the TOPSIS method is used in the ranking of alternative maintenance strategies. Five alternative maintenance strategies which include corrected maintenance, scheduled overhaul, scheduled replacement, continuous on-condition task and scheduled on-condition task are considered and the optimum maintenance strategy is selected based on twelve critical maintenance decision criteria. To demonstrate the suitability of the approach a case study of sea water pump of the central cooling system of a marine diesel engine is used.

Modern Maintenance Strategy of Electronic Equipment in Complex Electromechanical System

In this paper, the failure mechanism of electronic equipment was analysed.Aiming at the limitation of traditional maintenance modes, modern maintenance strategy was putforward on the basis of reliability-centered maintenance ( RCM) combined with condition-basedmaintenance ( CBM) and maintenance efficiency review (MER). A maintenance management informationsystem was constructed for electronic equipment for the purpose of failure analysis, reliabilityevaluation, and maintenance decisions such as time, mode, and plan. The best maintenance time couldbe predicted with failure analysis and reliability evaluation, which was mainly influenced byenvironmental stress. Suitable maintenance modes should be determined from equipment importance,failure aftereffect, maintenance condition, and economical power so as to ensure equipmentreliability and decrease the requirement of the maintenance source.

Study on Equipment Selective Maintenance Strategy Based on Performance

In this paper, an equipment selective maintenance strategy based on performance is brought forward according to the situation in China, in which reliability, computer technology, condition monitoring and management theory is applied. The theory points of the strategy are put forward. The maintenance strategy has been applied in mine hoist system.

Machinery and Equipment Maintenance Strategy and Choice

The advantages, disadvantages and characteristics of various maintenance strategies for modern mechanical equipment are analyzed. Combined with the system structure and functional characteristics of engineering equipment,it puts forward the selection method of maintenance strategies for different types of equipment and failure modes. The view of this article is that the comprehensive maintenance strategy, which is based on condition based maintenance(CBM) and combines various maintenance strategies. This will become the main development direction of engineering equipment maintenance.

Optimization of Equipment Maintenance Strategy Based on Availability

It is very important to optimize maintenance strategy in maintenance plan. Proper parameters play a decisive role for the optimization. In the opinion of writer, availability is a basic parameter, failure consequence cost and failure characteristic are also important parameters. Maintenance strategy can be optimized on the base by means of quantitative analysis and diagram.

Research on Network Maintenance Strategy Selection Based on Analytic Hierarchy Process and Technique for Order Preference by Similarity to Ideal Solution Algorithm

Network maintenance strategy selection is a multi-objective decision making topic. It mostly depends on the uncertainty and fuzziness of decision makers and conditions. In this paper, based on analytic hierarchy process(AHP) and technique for order preference by similarity to ideal solution(TOPSIS), TOPSIS partial order method is proposed to choose the optimal maintenance strategy. This method uses AHP to determine the weights of evaluation indexes. The optimal maintenance strategy choice is given as an example to demonstrate the effectiveness of the method.

Review of the Regulatory Requirements for the Maintenance of Aerobic Treatment Units and Greywater Treatment Systems in Western Australia

Aerobic Treatment Units (ATU) and Greywater Treatment Systems (GTS) are onsite wastewater treatment systems (OWTS) designed to treat wastewater to secondary effluent quality standards. Consequently, the electrical, mechanical and chemical components of these OWTS need to be regularly maintained to ensure their consistent and reliable operation to the required standards. In Western Australia (WA), the Department of Health set out the regulatory requirements for the maintenance of OWTS as well as when and how it is to occur. This paper reviews the maintenance requirements for ATU and GTS in WA and provides recommendations for the proposed changes in guidelines and regulations. State and national guidelines were reviewed and information from industry and regulators was obtained through surveys. The review found that although the guidelines are generally satisfactory there are a number of areas which could be improved and specific recommendations are discussed.

肺部超声检查在血液透析合并新型冠状病毒感染中的临床研究

目的探讨肺部超声检查在血液透析合并新型冠状病毒感染中的诊断及治疗策略,以期为临床同行提供参考依据。方法分析1例成功治愈的维持性血液透析合并重型新型冠状病毒感染患者的诊断、治疗等基本临床资料,采用“新型冠状病毒感染”“血液透析”“肺部超声检查”作为关键词对中国知网、PubMed数据库2020-2023年发表的文献进行检索。结果维持性血液透析合并新型冠状病毒感染患者经氧气治疗、抗病毒、抗炎、血液净化(利用肺部超声评估肺部B线变化)、抗感染、抗凝等治疗后痊愈出院,白细胞介素-6、淋巴细胞计数、C反应蛋白、降钙素原、红细胞沉降率、D-二聚体水平均正常,咽拭子新型冠状病毒核酸抗原检测阴性,床旁肺部超声检查提示双肺未见明显B线,肺部CT检查提示肺部渗出明显吸收。文献检索结果:共检索到文献35篇,排除16篇,最终保留可用文献19篇。结合病例分析及文献复习,对肺部超声检查在维持性血液透析合并新型冠状病毒感染中的临床诊断及治疗方法进行分析总结。结论床旁肺部超声检查在识别和分层维持性血液透析合并重型新型冠状病毒感染患者方面非常有效,可即时、准确评估患者的容量状态,保证患者透析的充分性。

可靠性约束下的重型数控机床维修策略

针对TH65140重型数控机床的各个子系统进行危害度分析,制定经济高效的预防性维修策略。通过威布尔分布对重型数控机床进行可靠性建模,在可靠度约束下,建立以最小维修费用和最大可用度为目标的机床子系统定期预防性维修模型,对模型进行求解得到了最优的维修次数及维修间隔期,制定出了重型数控机床的预防性维修策略。

基于新型细菌觅食优化算法的飞机动态泊位问题

随着航空运输业的发展,传统手动设计泊位方案已难以满足日益增长的外包维修需求.在外包模式下,如何快速给出高效的动态泊位方案关系到维修任务订单的准点交付,是飞机维修服务公司亟待解决的重要问题.针对飞机泊位进出顺序及碰撞检测特点,构建带时间窗的飞机维修泊位模型.设计自适应趋化学习及交叉协作策略,提出新型细菌觅食优化算法,并设计一系列约束处理机制.研究结果表明,提出的基于矩形碰撞检测方法可有效预防并判断飞机间碰撞阻塞情况.新型细菌觅食优化算法在解决飞机动态泊位问题上展现出搜索精度高、稳定性强等特点.所得高效智能化泊位调度方案有助于在保证维修安全的情况下提升飞机维修服务提供商的维修服务效率,改进维修资源利用率与维修系统的柔性,为企业实现高质量发展打下良好基础.

刀库式加工中心自动换刀系统故障诊断与维修

我国是制造大国,数控机床作为工业生产的重要设备,能够有效提升工业生产自动化水平。主要探讨了刀库式加工中心自动换刀系统的故障诊断与维修策略,详细介绍了自动换刀系统的组成,包括自动换刀装置和自动换刀控制系统,并分析了刀库故障、换刀机械手故障以及主轴松刀故障等多种常见问题。在自动换刀控制系统故障方面,着重分析了换刀点漂移、刀库乱刀和换刀超时等问题,并提出了相应的诊断和维修策略。希望本文的研究能为相关技术人员提供参考和借鉴。

网络安全运维工作中的攻击与防御

网络安全是指网络系统的硬件、软件及其系统中的数据受到保护,不因偶然的或者恶意的原因而遭到破坏、更改、泄露。在数据时代,信息安全逐渐成为人们关注的焦点。基于此,文章主要分析了网络安全运维工作中的攻击类型与防御策略。

网络安全运维领域中的实时威胁检测与应对策略研究

随着信息技术的不断发展,网络安全运维领域的实时威胁检测与应对策略显得尤为重要。文章首先深入分析网络安全运维领域中实时威胁检测的两种主要技术:基于签名的检测技术和基于行为分析的检测技术,其次探讨网络安全运维领域面临的实时威胁,包括零日攻击和高级持续性威胁,最后提出一系列应对策略,包括实时威胁情报的及时获取与分析、网络流量监控与异常行为检测,以及实施灵活的安全策略与演练应急响应计划,以帮助网络安全运维人员更好地防范和处理实时威胁。

战时维修任务动态抢占式调度方法研究

针对战时复杂约束下的装备维修任务和维修资源之间的矛盾,在充分考虑维修地点、维修装备重要度、维修资源、维修效率和维修时间等约束的前提下,提出了战时维修任务动态调度模型。为平衡维修资源与维修任务,提高任务成功率,结合战时需求提出相应的维修任务抢占策略,采用改进枚举法对抢占式调度模型进行求解。最后结合示例,对该调度模型的应用进行了验证,证明了该模型及算法的有效性。

基于实测数据的公路桥梁动态养修策略自适应优化模型

为了有效利用桥梁管养资源以确保桥梁在运营期的服役安全,本文构建了适用于公路桥梁的管养策略优化模型。基于1996—2020年间国内沿海地区208座及内陆地区176座存在历史养修工作的公路桥梁性能检测数据,建立了考虑养修时服役时长与养修频次的养修增益系数计算方法,并通过极大似然估计法计算出养修增益系数的取值范围。通过将改进逆高斯过程与贝叶斯更新方法结合建立了桥梁动态养修策略模型,并利用大量实测数据对模型性能进行评估,结果表明:模型预测平均相对误差为11.1%,可在一定程度上满足工程需要。采用改进后的灰狼算法对动态养修策略模型中的决策向量进行自适应优化,寻找使得剩余寿命累积成本最低的决策向量,并通过实际桥梁优化算例证实了决策向量最优解的存在以及自适应优化模型的有效性。

基于天窗基本单元的编组站天窗方案优化研究

编组站接发列车方向多、数量大,机车换挂和调车作业频繁,直接影响施工维修作业。既有固定天窗时长的天窗方案,难以兼顾维修施工作业和运输工作连续性需求,导致天窗兑现率低,增加安全隐患,研究提出基于天窗基本单元的编组站天窗方案优化方法。根据各维修养护工种作业特性、编组站工作人员数量及效率等因素,划分天窗基本单元;考虑编组站维修养护与运输组织需求,以效用、作业完成率和天窗阈值利用率最优为目标,以时序关系为约束,建立基于阈值的天窗方案多目标优化模型,并利用数学软件进行求解;以成都北编组站为例,验证模型的有效性,结果表明,通过合理优化天窗方案,天窗兑现率达100%,有助于缓解编组站维修与运输之间的冲突。

Product Modular Design Incorporating Preventive Maintenance Issues

Traditional modular design methods lead to product maintenance problems, because the module form of a system is created according to either the function requirements or the manufacturing considerations. For solving these problems, a new modular design method is proposed with the considerations of not only the traditional function related attributes, but also the maintenance related ones. First, modularity parameters and modularity scenarios for product modularity are defined. Then the reliability and economic assessment models of product modularity strategies are formulated with the introduction of the effective working age of modules. A mathematical model used to evaluate the difference among the modules of the product so that the optimal module of the product can be established. After that, a multi-objective optimization problem based on metrics for preventive maintenance interval different degrees and preventive maintenance economics is formulated for modular optimization. Multi-objective GA is utilized to rapidly approximate the Pareto set of optimal modularity strategy trade-offs between preventive maintenance cost and preventive maintenance interval difference degree. Finally, a coordinate CNC boring machine is adopted to depict the process of product modularity. In addition, two factorial design experiments based on the modularity parameters are constructed and analyzed. These experiments investigate the impacts of these parameters on the optimal modularity strategies and the structure of module. The research proposes a new modular design method, which may help to improve the maintainability of product in modular design.

Macromineral requirements of Dorper×thin-tailed Han crossbred female lambs

A comparative slaughter trial was conducted to determine the net mineral requirements for maintenance and growth of Dorper crossbred female lambs raised from 20 to 35 kg of body weight（BW）.Thirty-five Dorper×thin-tailed Han crossbred female lambs of（20.3±1.14） kg BW were used： 7 lambs were randomly chosen and slaughtered at the beginning of the experiment as the baseline group for measuring the initial body composition; another 7 lambs were randomly chosen and offered a pelleted mixed diet ad libitum and slaughtered at（27.0±0.73） kg BW; the remaining 21 lambs were randomly divided into 3 groups of 7 animals each and subjected to the same diet either ad l ibitum or at 70 or 40% of ad libitum intake.The 21 lambs were fed in 7 slaughter groups, with each group consisting of one lamb from each treatment（ad libitum, 70 or 40% of ad libitum intake）.The 3 groups were slaughtered when the sheep fed ad libitum attained（33.8±0.52） kg of BW.The body composition of five minerals（Ca, P, Na, K, and Mg） was determined.The net mineral requirements for maintenance were 35.01, 25.18, 9.30, 31.35, and 2.03 mg kg–1 empty BW（EBW） for Ca, P, Na, K, and Mg, respectively, and the net growth requirement per kg of EBW gain ranged from 9.73 to 8.87 g of Ca, 5.83 to 5.27 g of P, 1.73 to 1.63 g of Na, 3.73 to 4.08 g of K, and 0.26 to 0.25 g of Mg for Dorper crossbred lambs in China, respectively.The estimates of mineral requirements with Dorper crossbred lambs in the current study were not consistent with the recommendations from previous studies.