Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel ...Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.展开更多
Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and op...Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and optimizing the three properties are of great significance. A new approach for optimization of RMT parameters is proposed. First of all, the model for the equipment operation pro- cess is established based on the generalized stochastic Petri nets （GSPN） theory. Then, by solving the GSPN model, the quantitative relationship between operational availability and RMT parameters is obtained. Afterwards, taking history data of similar equipment and operation process into consideration, a cost model of design, manufacture and maintenance is developed. Based on operational availability, the cost model and parameters ranges, an optimization model of RMT parameters is built. Finally, the effectiveness and practicability of this approach are validated through an example.展开更多
To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainabili...To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.展开更多
During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do no...During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do not explain explicitly how to deal with this situation.This paper develops a comprehensive maintainability demonstration method for complex systems with a mixed maintenance time distribution.First of all,a K-means algorithm and an expectation-maximization(EM)algorithm are used to partition the maintenance time data for all possible clusters.The Bayesian information criterion(BIC)is then used to choose the optimal model.After this,the clustering results for equipment are obtained according to their degree of membership.The degree of similarity for the maintainability of different kinds of equipment is then determined using the projection method.By using a Bootstrap method,the prior distribution is obtained from the maintenance time data for the most similar equipment.Then,a test method based on Bayesian theory is outlined for the maintainability demonstration.Finally,the viability of the proposed approach is illustrated by means of an example.展开更多
An improved type of elliptical jacket polarization maintaining fiber was developed by using a modified chemical vapor deposition method with special treatment. Different from conventional elliptical jacket, the shape ...An improved type of elliptical jacket polarization maintaining fiber was developed by using a modified chemical vapor deposition method with special treatment. Different from conventional elliptical jacket, the shape of the stress jacket was transmuted. The cross-section of fiber consists of 5 layers: substrate, outer cladding, stress jacket, inner cladding and core. The cross sectional component distribution was investigated by electron probe microscopy and energy dispersive spectrum. The finite element method was used to calculate the stress birefringence. Based on the analyses of the microstructure, the technological process is improved. The temperature cycling test of the fiber wound into gyroscope coils was performed. The results show that the fiber possesses superior performance at high and low temperatures compared with other fibers. The high homogeneity is achieved by well-controlled modified chemical vapor deposition process. A homogeneous length of 8 km fiber is obtained. With advantages in homogeneity and length, the fiber has great potential in applications such as fiber gyroscopes, fiber hydrophone and other optical fiber sensors.展开更多
With China’s reform and development entering a critical period,the interweaving of various interest relations and the superimposing of the old and new contradictions have intensified social risks.Based on the concept...With China’s reform and development entering a critical period,the interweaving of various interest relations and the superimposing of the old and new contradictions have intensified social risks.Based on the concept of“pluralism,sharing,participation,cooperation and tolerance”,social stability can be maintained by the balanced protection of civil rights and the full realization of the development strategy.In addition,with the guidance of comprehensive legal thinking and core socialist values,the legal regulation of administrative behavior and rights-protection behavior is strengthened.In this way,the win-win of maintaining rights and stability can be realized in the positive-sum game that will help resolve social risks and achieve high-quality social stability.展开更多
文摘Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.
文摘Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and optimizing the three properties are of great significance. A new approach for optimization of RMT parameters is proposed. First of all, the model for the equipment operation pro- cess is established based on the generalized stochastic Petri nets （GSPN） theory. Then, by solving the GSPN model, the quantitative relationship between operational availability and RMT parameters is obtained. Afterwards, taking history data of similar equipment and operation process into consideration, a cost model of design, manufacture and maintenance is developed. Based on operational availability, the cost model and parameters ranges, an optimization model of RMT parameters is built. Finally, the effectiveness and practicability of this approach are validated through an example.
基金Project(51005238)supported by the National Natural Science Foundation of China
文摘To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.
基金supported by the National Defense Pre-research Funds(9140A27010215JB34422)
文摘During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do not explain explicitly how to deal with this situation.This paper develops a comprehensive maintainability demonstration method for complex systems with a mixed maintenance time distribution.First of all,a K-means algorithm and an expectation-maximization(EM)algorithm are used to partition the maintenance time data for all possible clusters.The Bayesian information criterion(BIC)is then used to choose the optimal model.After this,the clustering results for equipment are obtained according to their degree of membership.The degree of similarity for the maintainability of different kinds of equipment is then determined using the projection method.By using a Bootstrap method,the prior distribution is obtained from the maintenance time data for the most similar equipment.Then,a test method based on Bayesian theory is outlined for the maintainability demonstration.Finally,the viability of the proposed approach is illustrated by means of an example.
基金Project(50272019) supported by the National Natural Science Foundation of China project supported by China Postdoc toral Science Foundation
文摘An improved type of elliptical jacket polarization maintaining fiber was developed by using a modified chemical vapor deposition method with special treatment. Different from conventional elliptical jacket, the shape of the stress jacket was transmuted. The cross-section of fiber consists of 5 layers: substrate, outer cladding, stress jacket, inner cladding and core. The cross sectional component distribution was investigated by electron probe microscopy and energy dispersive spectrum. The finite element method was used to calculate the stress birefringence. Based on the analyses of the microstructure, the technological process is improved. The temperature cycling test of the fiber wound into gyroscope coils was performed. The results show that the fiber possesses superior performance at high and low temperatures compared with other fibers. The high homogeneity is achieved by well-controlled modified chemical vapor deposition process. A homogeneous length of 8 km fiber is obtained. With advantages in homogeneity and length, the fiber has great potential in applications such as fiber gyroscopes, fiber hydrophone and other optical fiber sensors.
文摘With China’s reform and development entering a critical period,the interweaving of various interest relations and the superimposing of the old and new contradictions have intensified social risks.Based on the concept of“pluralism,sharing,participation,cooperation and tolerance”,social stability can be maintained by the balanced protection of civil rights and the full realization of the development strategy.In addition,with the guidance of comprehensive legal thinking and core socialist values,the legal regulation of administrative behavior and rights-protection behavior is strengthened.In this way,the win-win of maintaining rights and stability can be realized in the positive-sum game that will help resolve social risks and achieve high-quality social stability.
