机床是将金属毛坯加工成机器零件的机器,它是制造机器的机器,所以又称为母机或"工具机",习惯上简称机床。现代机械制造中加工机械零件的方法很多:除切削加工外,还有铸造、锻造、焊接、冲压、挤压等,但凡属精度要求较高和表面...机床是将金属毛坯加工成机器零件的机器,它是制造机器的机器,所以又称为母机或"工具机",习惯上简称机床。现代机械制造中加工机械零件的方法很多:除切削加工外,还有铸造、锻造、焊接、冲压、挤压等,但凡属精度要求较高和表面粗糙度要求较细的零件,一般都需在机床上用切削的方法进行最终加工。在一般的机器制造中,机床所担负的加工工作量占机器总制造工作量的40%-60%,机床在国民经济现代化的建设中起着重大作用。而数控机床作为一项新技术,是数字控制机床(Computer numerical control machine tools)的简称,是一种装有程序控制系统的自动化机床。该控制系统能够逻辑地处理具有控制编码或其他符号指令规定的程序,并将其译码,用代码化的数字表示,通过信息载体输入数控装置。经运算处理由数控装置发出各种控制信号,控制机床的动作,按图纸要求的形状和尺寸,自动地将零件加工出来。展开更多
Most warranty cost models based on preventive maintenance operations are assumed that products improve at each preventive maintenance （PM） operation and the failure rate is reduced to the failure rate of new product...Most warranty cost models based on preventive maintenance operations are assumed that products improve at each preventive maintenance （PM） operation and the failure rate is reduced to the failure rate of new products or to some specified level. To make warranty cost models more suitable to real operations, a modeling method of the PM warranty cost was proposed with the situation where each PM operation slowed the rate of product degradation. A warranty cost model was built on PM operations. On the basis of the cost model, both without and with reliability limit PM warranty policy, algorithms were presented to derive the optimal PM number and the optimal PM interval with an objective of minimizing expected total warranty cost over a t＇mite warranty period. Finally, to demonstrate the feasibility of the presented modeling method, Weibuil distribution cases were tested by numerical simulations. The simulation results indicate that the proposed modeling method is feasible and valid for resolving the optimal solution of the product warranty cost.展开更多
The Korea Water Resources Corporation （K-Water） has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, ...The Korea Water Resources Corporation （K-Water） has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, lack of standards, and lack of planning. In this study, we have developed a mechanism for collecting, maintaining, and analyzing ground data for repair and replacement works. Our BMS （building maintenance system） uses the recorded repair and replacement work histories and calculates the life cycle costs of the related items. Further, it enables the performance of repair and replacement tasks through an integrated approach aimed at preventive maintenance. In this manner, the BMS is expected to maximize the efficiency of the formulation of prevention and maintenance work plans, monitoring of work histories, predictions of future tasks from the analyses of repair and replacement histories, and performance of LCC （life cycle cost） calculations. Reliable maintenance of national properties can thus be achieved by using the BMS, which promotes reasonable and efficient repair and replacement activities.展开更多
The lack of proper maintenance in buildings is responsible for various anomalies, which can cause property and personal damage. The objective of this study is to analyze the maintenance management of the administratio...The lack of proper maintenance in buildings is responsible for various anomalies, which can cause property and personal damage. The objective of this study is to analyze the maintenance management of the administration building at the Technological Park UFRJ/Brazil, trying to emphasize the relation between maintenance and good performance of the building and to demonstrate the need to develop a consistent maintenance system to achieve an efficient maintenance management. The study allowed to present strategies and possibilities of interventions, in addition to proposing the essential aspects for the development of a structured maintenance system. After reviewing the issue of building maintenance under the various perspectives presented, the importance of planning a preventive building maintenance, according to standards, to achieve the level of performance expected for the building, besides being essential the search for tools and methods that can increase the efficiency of management can be concluded. It is also pertinent to conclude that prevention is the most effective solution against the depreciation factors that affect a building, being the most economical viable, and ensuring other benefits for the building and its users, such as security, property valuation and attendance to the warranty period.展开更多
文摘机床是将金属毛坯加工成机器零件的机器,它是制造机器的机器,所以又称为母机或"工具机",习惯上简称机床。现代机械制造中加工机械零件的方法很多:除切削加工外,还有铸造、锻造、焊接、冲压、挤压等,但凡属精度要求较高和表面粗糙度要求较细的零件,一般都需在机床上用切削的方法进行最终加工。在一般的机器制造中,机床所担负的加工工作量占机器总制造工作量的40%-60%,机床在国民经济现代化的建设中起着重大作用。而数控机床作为一项新技术,是数字控制机床(Computer numerical control machine tools)的简称,是一种装有程序控制系统的自动化机床。该控制系统能够逻辑地处理具有控制编码或其他符号指令规定的程序,并将其译码,用代码化的数字表示,通过信息载体输入数控装置。经运算处理由数控装置发出各种控制信号,控制机床的动作,按图纸要求的形状和尺寸,自动地将零件加工出来。
基金National Natural Science Foundation of China(No.60574054No.70771065No.70671065)
文摘Most warranty cost models based on preventive maintenance operations are assumed that products improve at each preventive maintenance （PM） operation and the failure rate is reduced to the failure rate of new products or to some specified level. To make warranty cost models more suitable to real operations, a modeling method of the PM warranty cost was proposed with the situation where each PM operation slowed the rate of product degradation. A warranty cost model was built on PM operations. On the basis of the cost model, both without and with reliability limit PM warranty policy, algorithms were presented to derive the optimal PM number and the optimal PM interval with an objective of minimizing expected total warranty cost over a t＇mite warranty period. Finally, to demonstrate the feasibility of the presented modeling method, Weibuil distribution cases were tested by numerical simulations. The simulation results indicate that the proposed modeling method is feasible and valid for resolving the optimal solution of the product warranty cost.
文摘The Korea Water Resources Corporation （K-Water） has encountered four problems during the management of water resources of approximately 1,300 buildings spread throughout the country-degradation, budget constraints, lack of standards, and lack of planning. In this study, we have developed a mechanism for collecting, maintaining, and analyzing ground data for repair and replacement works. Our BMS （building maintenance system） uses the recorded repair and replacement work histories and calculates the life cycle costs of the related items. Further, it enables the performance of repair and replacement tasks through an integrated approach aimed at preventive maintenance. In this manner, the BMS is expected to maximize the efficiency of the formulation of prevention and maintenance work plans, monitoring of work histories, predictions of future tasks from the analyses of repair and replacement histories, and performance of LCC （life cycle cost） calculations. Reliable maintenance of national properties can thus be achieved by using the BMS, which promotes reasonable and efficient repair and replacement activities.
文摘The lack of proper maintenance in buildings is responsible for various anomalies, which can cause property and personal damage. The objective of this study is to analyze the maintenance management of the administration building at the Technological Park UFRJ/Brazil, trying to emphasize the relation between maintenance and good performance of the building and to demonstrate the need to develop a consistent maintenance system to achieve an efficient maintenance management. The study allowed to present strategies and possibilities of interventions, in addition to proposing the essential aspects for the development of a structured maintenance system. After reviewing the issue of building maintenance under the various perspectives presented, the importance of planning a preventive building maintenance, according to standards, to achieve the level of performance expected for the building, besides being essential the search for tools and methods that can increase the efficiency of management can be concluded. It is also pertinent to conclude that prevention is the most effective solution against the depreciation factors that affect a building, being the most economical viable, and ensuring other benefits for the building and its users, such as security, property valuation and attendance to the warranty period.
