遗传算法在串-并联冗余系统可靠性优化设计中的应用

串-并联冗余系统可靠性的最优设计是可靠性技术中一个十分重要的问题。讨论了遗传算法及其在串-并联冗余系统可靠性优化设计中的应用。串-并联冗余系统具有冗余单元和可选设计，其可靠性优化设计是一高度非线性、具有多极值点、有约束的整数规划问题，传统的解决方法往往对于连续实数域有效可行，而对于解决此类多变量，离散型整数域取值的复杂的优化问题则往往很困难。由于遗传算法是一类全局收敛算法，它用点群进行寻优，而不是用一个单点进行寻优，具有隐含并行算法的特点，从而能够得到全局最优解。所给出的实例说明本文的算法是有效可行的。     

基于造价和维修费用的系统可靠性指标分配方法

可靠性指标分配是人力、物力统一调度和合理运用的一个工程决策问题，是与工程系统造价、维修费用密切相关的。因此，在进行系统可靠性分配时，必须同时考虑工程系统的造价和维修费用。本文给出了工程系统造价与可靠度的关系式和系统维修费用期望值与可靠度的关系式，建立了考虑造价与维修费用的系统可靠性模糊优化分配数学模型，从一而提出了基于造价和维修费用的系统可靠性指标分配方法，并给出了该方法的工程应用算例。结果表明：本文方法科学合理、简单实用，具有一定的工程应用价值。     

Bi-objective redundancy allocation problem for a system with mixed repairable and non-repairable components

Traditionally, in the redundancy allocation problem (RAP), two general classes of optimization problems are considered; reliability optimization and availability optimization. Contrary to reliability optimization, fewer researchers have studied availability optimization to find out the optimal combination of components type and redundancy levels for each subsystem in a system for maximizing (or minimizing) the objectives. In each problem it is assumed that either the entire components are repairable or they are non-repairable. However, in real world situations, systems usually consist of both repairable and non-repairable components. In this paper a new Mixed Integer Nonlinear Programming (MINLP) model is presented to analyze the availability optimization of a system with a given structure, using both repairable and non-repairable components, simultaneously. To find the solution of the introduced MINLP, an efficient Genetic Algorithm (GA) is also developed. Furthermore, to show the efficiency of the proposed GA, a numerical example is presented. Experimental results demonstrate that the proposed GA has a better performance compared to one of the most recommended algorithm in the literature.     

机械系统可靠性优化设计的实现策略

提出机械系统可靠性优化设计的３种实现策略：一是直接求解系统可行性优化设计整体数学规划模型的耦合优化策略;二是将单元可靠性优化设计模型和系统可靠性优化分配模型联立迭代求解的分解协调经策略;三是将单元可靠性优化分配模型分别独立求解的分散优化策略。前者适用于规模不大的机械系统的可靠性优化设计,后二者适用于规模较大的机械系统的可靠性优化设计。     

基于改进模糊综合评价法的射电望远镜可靠性评估

射电望远镜的可靠性问题广泛存在于射电望远镜设计、制造、正常工作等整个全寿命周期,对其子系统进行可靠性评估与可靠性指标分配是射电望远镜设计阶段的关键步骤。文中从射电望远镜的可靠性评估与可靠性指标分配出发,提出了一种基于粒子群优化层次分析的模糊综合评价模型,并基于此模型从多指标综合模糊评价角度对射电望远镜的子系统进行了可靠性评估与可靠性指标分配。可靠性评估分配结果表明射电望远镜子系统中可靠性评估最低的是主反射面系统,需要根据评估结果分配较高的可靠性指标并针对性地提高其可靠性以提高系统的整体可靠性。     

基于遗传算法的复杂系统可靠性冗余优化研究

由于复杂系统可靠度函数常具有非线性的特点，因此如何确定复杂系统各单元冗余数，既满足设计可靠度要求、又使系统成本最小是冗余优化问题中的一个难点。文中针对复杂系统的特点，提出一种基于遗传算法的多目标可靠性冗余优化方法。同时，将其和现有的可靠性冗余优化方法进行了比较分析，结果表明该方法具有全局最优和更强的适应性与求解能力。     

采用多级模糊评价的柴油机可靠性分配

可靠性分配是可靠性设计的一个重要的环节。影响系统可靠性的因素很多,将模糊理论应用在可靠性设计的初级阶段,采用多级模糊综合评价方法对多类别、多层次又具有模糊性的各因素的影响进行综合和量化是一种有效的方法。具体介绍了多级模糊综合评价方法,并应用该方法对柴油机某子系统进行了可靠性分配。     

SIS冗余结构可靠性影响参数分析

可靠性是衡量安全仪表系统性能（SIS）优劣的重要指标之一。本文基于故障树模型的SIS可靠性公式,对安全仪表系统常用5种冗余结构5个参数进行Matlab程序仿真,直观的分析各参数对SIS常用冗余结构可靠性的影响,分析冗余结构可靠性性能关系,分析结果对安全仪表系统的设计和整改具有重要意义。     

直齿圆柱齿轮传动的模糊可靠性优化设计

在工程系统可靠性优化设计时考虑了模糊可靠度约束；并对直齿圆柱齿轮建立了目标函数，确立了其模糊可靠度约束条件，最后给出一个实例验证了此法。     

设计指标最优分配的协同方法

设计指标最优分配是飞机顶层设计中的一个关键问题。本文借鉴协同优化思想,发展了一种新的设计指标最优分配方法———协同分配法(collaborative allocation),用于处理飞机顶层设计中的大规模设计指标最优分配问题。给出了协同分配法的分配思想并建立了该方法的数学模型。用一个可靠度指标最优分配算例说明了协同分配法的数学模型建立及求解过程,初步验证了该方法对设计指标最优分配的有效性。     

Reliability analysis of the control system of large-scale vertical mixing equipment

The control system of vertical mixing equipment is a concentrate distributed monitoring system (CDMS). A reliability analysis model was built and its analysis was conducted based on reliability modeling theories such as the graph theory, Markov process, and redundancy theory. Analysis and operational results show that the control system can meet all technical requirements for high energy composite solid propellant manufacturing. The reliability performance of the control system can be considerably improved by adopting a control strategy combined with the hot spared redundancy of the primary system and the cold spared redundancy of the emergent one. The reliability performance of the control system can be also improved by adopting the redundancy strategy or improving the quality of each component and cable of the system.     

Reliability analysis of the control system of large-scale vertical mixing equipment

The control system of vertical mixing equipment is a concentrate distributed monitoring system (CDMS). A reliability analysis model was built and its analysis was conducted based on reliability modeling theories such as the graph theory, Markov process, and redundancy theory. Analysis and operational results show that the control system can meet all technical requirements for high energy composite solid propellant manufacturing. The reliability performance of the control system can be considerably improved by adopting a control strategy combined with the hot spared redundancy of the primary system and the cold spared redundancy of the emergent one. The reliability performance of the control system can be also improved by adopting the redundancy strategy or improving the quality of each component and cable of the system.     

圆弧齿圆柱齿轮传动的模糊可靠性优化设计

圆弧齿轮传动设计中,诸如工作应力、极限应力等设计参数及其影响因素很多都具有模糊性。为对模糊性进行定量分析处理,本文运用模糊论方法建立了以模糊可靠度等为约束条件,以体积最小为目标的优化数学模型。求解时,则采用了混合离散变量优化方法,以避免优化结果因齿数等离散变量圆整所引起的劣化。实例表明,模糊可靠性优化设计是一种更具科学性、更符合客观实际要求的设计方法。     

Tool Wear Length Estimation with a Self-Learning Fuzzy Inference Algorithm in Finish Milling

The geometric accuracy and surface roughness are mainly affected by the flank wear at the minor cutting edge in finish machining. A genetic algorithm-based fuzzy estimator obtained by a fuzzy inference algorithm to evaluate the minor flank wear length in finish milling is introduced. The fuzzy inference rules are trained by genetic algorithms (GA) through practice. Fuzzy membership functions and rules are usually decided upon subjectively. In this paper, the performance of the fuzzy estimator may be improved if the fuzzy inference model is supplemented by a genetic-based learning mechanism. The features sensitive to minor flank wear are extracted from the dispersion analysis of a time series AR model of the feed directional acceleration of the spindle housing. Linguistic rules for fuzzy estimation are constructed using these features, and then fuzzy inferences are carried out with test data sets under various cutting conditions. The proposed system turns out to be effective for estimating minor flank wear length, and its mean error is less than 13%.     

Non-sample based parameters design for system performance reliability improvement

Design methods for quality generally help to improve quality over time, but do not consider change of system performance over time, resulting from degradation in components. As design methods for quality over time (performance reliability), which minimizes effects of unavoidable component degradations as well as component variations on system performance change, system model-based sampling methods using Monte-Carlo simulations have been used. But, there are main concerns related to computational efficiency and optimization in applying the sampling methods. To overcome the concerns, we propose a non-sample method for quality over time. Based on the proposed method, the process of allocating design parameters, which could minimize the noise effects with the consequence that both quality and performance reliability are optimized, is discussed. Reliability metrics such as mean time to failure and standard deviation of time to failure are optimized simultaneously for reliability improvement. Desirability functions for the metrics are introduced to perform the simultaneous optimization. The proposed method is applied to an electrical system design and compared to a sampling based design method.     

基于传动性能的齿轮传动系统精度模糊优化设计

利用并行工程和图论的相关理论,将齿轮传动系统中各个零部件之间精度设计的关系联系起来,建立了关系模型;以齿轮系统传动性能的要求作为零部件精度设计的主要设计目标,通过将系统各个零部件的误差进行归一化处理,推导出影响齿轮传动性能的齿轮转角误差,并将从输入轴到输出轴上的所有齿轮副及其零部件综合构成的传动链误差作为目标函数,利用模糊理论将各项经验参数进行模糊量化处理,把各精度的限制性条件和加工工艺成本作为约束条件,进行优化设计,获得最佳的零部件精度组合和准确的传动性能参数,指导传动系统设计.     

A type-2 fuzzy expert system based on a hybrid inference method for steel industry

In this paper, a novel type-2 fuzzy expert system for prediction the amount of reagents in desulfurization process of a steel industry in Canada is developed. In this model, the new interval type-2 fuzzy c-regression clustering algorithm for structure identification phase of Takagi–Sugeno (T–S) systems is presented. Gaussian Mixture Model is used to generate partition matrix in clustering algorithm. Then, an interval type-2 hybrid fuzzy system, which is the combination of Mamdani and Sugeno method, is proposed. The new hybrid inference system uses fuzzy disjunctive normal forms and fuzzy conjunctive normal forms for aggregation of antecedents. A statistical test, which uses least square method, is implemented in order to select variables. In order to validate our method, we develop three system modeling techniques and compare the results with our proposed interval type-2 fuzzy hybrid expert system. These techniques are multiple regression, type-1 fuzzy expert system, and interval type-2 fuzzy TSK expert system. For tuning parameters of the system, adaptive-network-based fuzzy inference system is used. Finally, neural network is utilized in order to reduce error of the system. The results show that our proposed method has less error and high accuracy.     

Accuracy analysis and design of A3 parallel spindle head

As functional components of machine tools, parallel mechanisms are widely used in high efficiency machining of aviation components, and accuracy is one of the critical technical indexes. Lots of researchers have focused on the accuracy problem of parallel mechanisms, but in terms of controlling the errors and improving the accuracy in the stage of design and manufacturing, further efforts are required. Aiming at the accuracy design of a 3-DOF parallel spindle head(A3 head), its error model, sensitivity analysis and tolerance allocation are investigated. Based on the inverse kinematic analysis, the error model of A3 head is established by using the first-order perturbation theory and vector chain method. According to the mapping property of motion and constraint Jacobian matrix, the compensatable and uncompensatable error sources which affect the accuracy in the end-effector are separated. Furthermore, sensitivity analysis is performed on the uncompensatable error sources. The sensitivity probabilistic model is established and the global sensitivity index is proposed to analyze the influence of the uncompensatable error sources on the accuracy in the end-effector of the mechanism. The results show that orientation error sources have bigger effect on the accuracy in the end-effector. Based upon the sensitivity analysis results, the tolerance design is converted into the issue of nonlinearly constrained optimization with the manufacturing cost minimum being the optimization objective. By utilizing the genetic algorithm, the allocation of the tolerances on each component is finally determined. According to the tolerance allocation results, the tolerance ranges of ten kinds of geometric error sources are obtained. These research achievements can provide fundamental guidelines for component manufacturing and assembly of this kind of parallel mechanisms.     

系统可靠性的冗余分配及其0－1整数规划模型

冗余设计是改善系统可靠性的一种有效方法。本文综述了最优冗余分配方法的发展现状，简要介绍了神经网络的基本原理及特点，讨论了将冗余分配问题转化为便于神经网络求解的０—１整数规划问题的数学模型的建立方法。     

Reliability optimization design of hydraulic system considering oil contamination

This paper presents a reliability optimization design method for a hydraulic system that considers oil contamination. The proposed method applies the quantitative relationship between oil contamination and system reliability to the reliability design of a hydraulic system, while considering the performance, layout, and other design factors. A global reliability model of the hydraulic system is constructed based on the oil contamination control model. Further studies aiming at an optimization design model of the hydraulic system is established where the cost is the objective function, reliability index, size and structure range, performance requirements are constraints, structure size and oil change period are design variables. For illustration, a case study on the reliability optimization design of the oil supply point branch of the static pressure bracket of a certain type of heavy CNC horizontal lathe is considered.