Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Departmen...Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Department of Roads (DoR) is responsible for maintenance of strategic roads of country. The maintenance practice of the road under Department of Road is predominantly based on Strengthen Maintenance Division Process where several maintenance activities like Routine maintenance, Recurrent Maintenance, Periodic Maintenance and Emergency Maintenance are planned and carried out. The maintenance work is based on traditional quantity and unit price based short term maintenance contracts, where maintenance of physical works is outsourced. Client demands the contractor what work is to be done, when to be do it and the extent of the work. The contractor is paid on the basis of a defined output or quantity accomplished, and the schedule of the rates. DoR engineers required full time supervision of work. Pilot based performance based maintenance practice of road started in Nepal in 2003. The study assesses performance road maintenance practices of road maintenance in Nepal on the basis of the framework of cost efficiency, level of service effectiveness and quality of service. The study concluded that implementation of Performance Based Maintenance Contract (PBMC) was not successful in Nepal as Road Asset condition was not maintained to performance standard. One of the reasons is the weak service delivery of contractor alongside weak contract enforcement from the road agency.展开更多
Real-time performance and reliability are two most important issues in applications of time-triggered controller area network （CAN） bus systems at present. A scheduling matrix of time-triggered CAN-bus system is est...Real-time performance and reliability are two most important issues in applications of time-triggered controller area network （CAN） bus systems at present. A scheduling matrix of time-triggered CAN-bus system is established using average-loading algorithm. Periodic messages are guaranteed to transmit without delay by distributing independent transmission windows within the system matrix. Considering the traditional CAN-bus transmission mechanism and the time-triggered feature, an algorithm is improved to calculate the worst-case delay of event-triggered messages in time-triggered CAN-bus systems. The failure probability is calculated for event-triggered messages whose worst-case delay exceeds their deadlines. Different levels of redundant structures of CAN-bus circuits are analyzed and the maintenance management is proposed to improve the system reliability. Finally, the reliabilities of different structures are calculated and the influences of maintenance on the system reliability are analyzed.展开更多
文摘Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Department of Roads (DoR) is responsible for maintenance of strategic roads of country. The maintenance practice of the road under Department of Road is predominantly based on Strengthen Maintenance Division Process where several maintenance activities like Routine maintenance, Recurrent Maintenance, Periodic Maintenance and Emergency Maintenance are planned and carried out. The maintenance work is based on traditional quantity and unit price based short term maintenance contracts, where maintenance of physical works is outsourced. Client demands the contractor what work is to be done, when to be do it and the extent of the work. The contractor is paid on the basis of a defined output or quantity accomplished, and the schedule of the rates. DoR engineers required full time supervision of work. Pilot based performance based maintenance practice of road started in Nepal in 2003. The study assesses performance road maintenance practices of road maintenance in Nepal on the basis of the framework of cost efficiency, level of service effectiveness and quality of service. The study concluded that implementation of Performance Based Maintenance Contract (PBMC) was not successful in Nepal as Road Asset condition was not maintained to performance standard. One of the reasons is the weak service delivery of contractor alongside weak contract enforcement from the road agency.
基金supported by Fundamental Research Funds for the Central Universities and National Science and Technology Major Project (No. 2010ZX04014-017)
文摘Real-time performance and reliability are two most important issues in applications of time-triggered controller area network （CAN） bus systems at present. A scheduling matrix of time-triggered CAN-bus system is established using average-loading algorithm. Periodic messages are guaranteed to transmit without delay by distributing independent transmission windows within the system matrix. Considering the traditional CAN-bus transmission mechanism and the time-triggered feature, an algorithm is improved to calculate the worst-case delay of event-triggered messages in time-triggered CAN-bus systems. The failure probability is calculated for event-triggered messages whose worst-case delay exceeds their deadlines. Different levels of redundant structures of CAN-bus circuits are analyzed and the maintenance management is proposed to improve the system reliability. Finally, the reliabilities of different structures are calculated and the influences of maintenance on the system reliability are analyzed.
