Zhexue Ge

Maintainability-based facility layout optimum design of ship cabin

Maintainability of a mechanical system is one of the system design parameters that has a great impact in terms of ease of maintenance. In this paper, a methodology of facility layout optimum design for maintainability of a ship cabin is presented as a way to improve the efficiency and quality of maintainability design. The maintenance operating space, amount of hoisting, balance of cabin, distance requirement and personnel movement distance are all taken into account, and treated as objective functions. The mechanical functional constraints and some important layout experience are also considered and formulated as constraints. Thus, the mathematical model for maintainability layout combinatorial optimisation is constructed. According to the characteristics of maintainability-based facility layout problem, the particle swarm optimisation algorithm developed by Eberhart and Kennedy is modified to enhance the computational efficiency and solution accuracy. A hybrid position updating method is used to solve the optimisation problem with both continuous and discrete variables. The dynamic neighbourhood structure, dynamic inertia weight and adaptive mutation mode are modified to effectively solve the optimisation problem with multiple peak values. Finally, the methodology proposed is illustrated by simulation case and engineering application, and the results suggest that the methodology is effective.

Fuzzy grey relational analysis of design factors influencing on maintainability indices

Maintainability is a design attribute of a product, and its relationship with the design factors is complicated. In consideration of the fuzziness and uncertainty of design factors that influences the products maintainability indices, we propose a method based on fuzzy grey relational analysis to determine their prioritization in this paper. First, the evaluation methods of various design factors and how these factors affect product maintainability indices are analyzed. Then, the fuzzy grey relational analysis model of the relationship between the design factors and maintainability indices is set up, and the prioritization of design factors to maintainability indices is achieved. Finally, the proposed methods are applied on a subsystem of a manned spacecraft, which indicates that the proposed method can quantitatively analyze the influencing degree of the design factors to maintainability indices. This information can be used to guide maintainability indices evaluation modeling based on digital mock-up in the design phase and help to catch the major influencing design factors in maintainability design.

A method for the maintainability assessment at design stage based on maintainability attributes

The objective of this paper is to describe a procedure to evaluate system maintainability at the design stage, the results of which can support concurrent decision-making with specified maintenance requirements and the guidance of maintainability design improvement. With this purpose, maintainability indicators for decision-making and design guidance are defined based on the maintainability attributes to evaluate the system maintainability. In order to improve the objectivity and accuracy of maintainability assessment, maintainability attributes are analyzed and classified according to the view of maintenance. Then, the basic evaluation object levels and quantitative evaluation methods of maintainability attributes are presented. Based on evaluation values of maintainability attributes, the maintainability indicators are obtained using different algorithms. Finally, a case is studied to demonstrate how the proposed evaluation method can be applied in a real case.

A modeling method for continuous quantization of maintenance accessibility

Good accessibility is an important guarantee for maintenance operation tasks. Aiming at overcoming the deficiency that the degree of being accessible for points in space cannot be described by current indices related to accessibility and the problem that accessibility design and analysis cannot be conducted conveniently, for the first time, the paper proposes a modeling method for continuous quantization of maintenance accessibility. On the basis of the kinematic model of human body, the functions of influence on accessibility are established. A model of continuous quantization of maintenance accessibility is then constructed. Taking human arm as the research object, a corresponding model of continuous quantization of accessibility is set up and a visual simulation of accessibility of points in space is conducted by the use of the proposed method.

Maintenance time estimation method in the design phase based on fuzzy v-support vector machine

This paper presents a new estimation method of maintenance time in the design phase based on fuzzy v-support vector machine (Fv-SVM), considering the problems of finite samples and uncertain data in the maintenance time estimation. The maintenance task of product is first decomposed into many elementary maintenance activities. The influence of design factors on product maintenance time is analyzed, and the important design factors which influence the time of single maintenance operation are determined. Then, the design factors are quantified by triangular fuzzy numbers, and a time estimation method of maintenance operation based on Fv-SVM is proposed. The results of the application in maintenance time estimation confirm the feasibility and the validity of the estimation method.

Visibility Modeling of Operating Space Layout and Particle Swarm Optimization

the layout of operating space must meet the requirement of visibility. In order to improve the visibility and design efficiency of work space layout, optimization design method targeted in visibility was proposed in this paper. Primarily, a visibility model of three-dimensional space was established according to visual characteristics of human eyes, with emphasis on analyzing the influence of space obstacles to visibility. On this basis, this paper set up an optimization design working space layout model, with introducing layout visibility objective function. Optimal design scheme was obtained by studying and applying the results of particle swarm optimization (PSO) algorithm based on natural selection. Finally, the application of typical example verified the effectiveness and practicality of the visibility work place optimization design.