Inadequate maintenance decisions lead to incremental overall costs. In order to minimize costs in maintenance of the multi-state repairable system, we model a preventive maintenance(PM) scheme of the multistate repair...Inadequate maintenance decisions lead to incremental overall costs. In order to minimize costs in maintenance of the multi-state repairable system, we model a preventive maintenance(PM) scheme of the multistate repairable system using non-Markov process. The periodically decreasing reliability model of the non-Markov dynamic system with dynamic transition probabilities is established to satisfy the probability change. The diesel engine system is taken as an example to illustrate the model. The reliability of the diesel engine is analyzed and its PM scheme is worked out. RENO software is used to simulate the diesel engine system. The maintenance cost of components and the optimal PM interval data of the system are obtained by using the minimal average cost as the objective function. The adaptability of PM is judged, and the optimal PM scheme is presented.展开更多
In the surrounding environment, lead (Pb) can be released by repairing some parts of automobile engine and radiators repair works. Lead is very well-known as a neurotoxicant as some links exist between blood lead leve...In the surrounding environment, lead (Pb) can be released by repairing some parts of automobile engine and radiators repair works. Lead is very well-known as a neurotoxicant as some links exist between blood lead level (BLL) and neurological outcomes. This cross sectional study was performed on 35 male workers who were 23 - 40 and worked in an automobile repair shop located in an industrial part of Tehran. Clinical evidences were recorded by a questionnaire. Subjects had given their blood samples between 7 and 8 a.m. before going to work. The levels of hematological parameters were measured and the amount of lead in plasma samples was determined by graphite-furnace atomic absorption spectrophotometer. The Iranian versions of mood state and Wechsler memory questionnaire were applied in order to evaluate mood and memory impairment. The association between variables was studied using Pearson correlation coefficient. A positive correlation was seen between workers’ history on one side and, urinary frequency and restlessness on the other side. There was not any meaningful relationship between worker history, blood parameters, and mood state. A negative meaningful relationship existed between the workers’ history and visual memory. Also a positive significant relationship was observed between BLL and epigastric pain and there was a negative relationship between BLL and repeat number. There was not a significant relationship between BLL, blood parameters, and mood state as well. It was concluded that work practices in the automobile repair shop seemed to increase the body burden of lead and may pose a health risk to the workers.展开更多
A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the origi...A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the original faultless system.The compensating controller can be seen as a standalone loop added to the system to compensate the effects of fault guaranteeing the stability of the system.A design method is proposed using nonlinear dynamic inverse control as the main controller and nonlinear extended state observer-based compensator.The stability of the whole closed-loop system is analyzed.Feasibility and validity of the new controller is demonstrated with an aircraft simulation example.展开更多
基金the National Natural Science Foundation of China(Nos.61164009 and 61463021)the Science Foundation of Education Commission of Jiangxi Province(No.GJJ14420)+1 种基金the Young Scientists Object Program of Jiangxi Province(No.20144BCB23037)the Natural Science Foundation of Jiangxi Province(No.20132BAB206026)
文摘Inadequate maintenance decisions lead to incremental overall costs. In order to minimize costs in maintenance of the multi-state repairable system, we model a preventive maintenance(PM) scheme of the multistate repairable system using non-Markov process. The periodically decreasing reliability model of the non-Markov dynamic system with dynamic transition probabilities is established to satisfy the probability change. The diesel engine system is taken as an example to illustrate the model. The reliability of the diesel engine is analyzed and its PM scheme is worked out. RENO software is used to simulate the diesel engine system. The maintenance cost of components and the optimal PM interval data of the system are obtained by using the minimal average cost as the objective function. The adaptability of PM is judged, and the optimal PM scheme is presented.
基金the National Natural Science Foundation of China(Nos.51675414,51805416)the Joint Fund for Aerospace Advanced Manufacturing Technology Research Key Program,China(No.U1937203).
文摘In the surrounding environment, lead (Pb) can be released by repairing some parts of automobile engine and radiators repair works. Lead is very well-known as a neurotoxicant as some links exist between blood lead level (BLL) and neurological outcomes. This cross sectional study was performed on 35 male workers who were 23 - 40 and worked in an automobile repair shop located in an industrial part of Tehran. Clinical evidences were recorded by a questionnaire. Subjects had given their blood samples between 7 and 8 a.m. before going to work. The levels of hematological parameters were measured and the amount of lead in plasma samples was determined by graphite-furnace atomic absorption spectrophotometer. The Iranian versions of mood state and Wechsler memory questionnaire were applied in order to evaluate mood and memory impairment. The association between variables was studied using Pearson correlation coefficient. A positive correlation was seen between workers’ history on one side and, urinary frequency and restlessness on the other side. There was not any meaningful relationship between worker history, blood parameters, and mood state. A negative meaningful relationship existed between the workers’ history and visual memory. Also a positive significant relationship was observed between BLL and epigastric pain and there was a negative relationship between BLL and repeat number. There was not a significant relationship between BLL, blood parameters, and mood state as well. It was concluded that work practices in the automobile repair shop seemed to increase the body burden of lead and may pose a health risk to the workers.
基金supported by the National Natural Science Foundation of China (60874117)the 111 Project (B07009)
文摘A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the original faultless system.The compensating controller can be seen as a standalone loop added to the system to compensate the effects of fault guaranteeing the stability of the system.A design method is proposed using nonlinear dynamic inverse control as the main controller and nonlinear extended state observer-based compensator.The stability of the whole closed-loop system is analyzed.Feasibility and validity of the new controller is demonstrated with an aircraft simulation example.
