Progress in the design of the ITER Neutral Beam cell Remote Handling System

The ITER Neutral Beam cell will include a suite of Remote Handling equipment for maintenance tasks. This paper summarises the current status and recent developments in the design of the ITER Neutral Beam Remote Handling System. Its concept design was successfully completed in July 2012 by CCFE in the frame of a grant agreement with F4E, in collaboration with the ITER Organisation, including major systems like monorail crane, Beam Line Transporter, beam source equipment, upper port and neutron shield equipment and associated tooling. Research and development activities are now underway on the monorail crane radiation hardened on-board control system and first of a kind remote pipe and lip seal maintenance tooling for the beam line vessel, reported in this paper.     

Clonal selection algorithm for power generators maintenance scheduling

This paper introduces a technique based on the one of the artificial immune system (AIS) technique known as the clonal selection algorithm (CSA) to obtain the optimal maintenance schedule outage of generating units. Based on a weekly load profile, the proposed technique provides the optimal maintenance window and calculates the optimal output power from each generator over a one year horizon. The maintenance scheduling problem is decoupled into two interrelated sub-problems namely, the maintenance scheduling and the power system sub-problems. The CSA is used to solve the maintenance scheduling subproblem to obtain the optimal maintenance outage of each unit. Based on the schedule generated by the CSA, the economic dispatch iterative lambda technique is used to find the optimal output power from each unit. Due to the search nature of the CSA, infeasible solutions may be introduced during the solution process. Therefore, a local search technique is used to watch the feasibility of the new solutions. The paper reports test results of the proposed algorithm to find the optimal maintenance schedule of the IEEE 30 bus system with 6 generating units and the IEEE 118 bus system with 33 generating units. Results are compared against the results obtained by complementary decision variables structure (CDV) and the evolutionary programming based techniques. Results are encouraging and indicate the viability of the proposed CSA technique.     

Managing chipper knife wear to increase chip quality and reduce chipping cost

Wood biomass is turned into industrial fuel through chipping. The efficiency of chipping depends on many factors, including chipper knife wear. Chipper knife wear was determined through a long-term follow-up study, conducted at a waste wood recycling yard. Knife wear determined a sharp drop of productivity (>20%) and a severe decay in product quality. Dry sharpening with a grinder mitigated this effect, but it could not replace proper wet sharpening. Increasing the frequency of wet sharpening sessions determined a moderate increase of knife depreciation cost, but it could drastically enhance machine performance and reduce biomass processing cost. Since benefits largely exceed costs, increasing the frequency of wet sharpening sessions may be an effective measure for reducing overall chipping cost. If the main goal of a chipper operator is to increase productivity and/or decrease fuel consumption, then managing knife wear should be a primary target.     

面向人为差错的多通道约束匹配模型

为减少用户使用产品时出现人为差错的概率,提高产品的使用效率,建立了面向人为差错的多通道约束匹配模型。分别从认知层面与执行层面对造成人为差错的因素进行探讨,应用基于假设的真值维护系统理论得到3种差错类型,分别为认知错误、认知失效和操作失误。从视觉、听觉和触觉3个通道为产品加载设计约束,构造问题求解器,建立差错类型环境与通道类型集合的映射关系,从而得到多通道约束匹配模型,实现非单调推理。以某品牌车载导航仪为例,提取人为差错因子,基于多通道约束匹配模型架构建立导航任务过程中的面向人为差错的多通道约束子模型,并通过该子模型找到导航出错的有效约束,从而减少车载导航仪在使用过程中产生的人为差错,提升车载导航仪使用绩效。建立面向人为差错的多通道约束匹配模型,为减少用户使用产品出现人为差错提供了基础研究架构。     

Priority setting in maintenance management: a modified multi-attribute approach using analytic hierarchy process

In the current economic climate, budgets for the maintenance of public buildings are unlikely to meet the ever-increasing maintenance needs. Although it is unlikely that this problem can be overcome completely without an injection of further resources, it is possible for government maintenance authorities to improve the situation by ensuring that the best solution in terms of ‘value for money’ is achieved in the planned maintenance programme. A maintenance plan which is based on a rational assessment of priorities and up-to-date knowledge of the condition of the property stock will help to ensure the best use of available resources. Based on the multi-attribute maintenance prioritization model developed by Alan Spedding, Roy Holmes and Qiping Shen at the University of West of England, which is simple in practice and flexible from a management point of view, this paper presents the results of some further research into this area by modifying the original model using an analytical hierarchy process in deciding the weightings of the criteria set out in the prioritization model. This modified model is more quantitative and objective than the original model. The validation of the framework is also discussed.     

Management of small building works

This paper focuses on the management dimension of small building works. The paper presents a subset of findings from a major research study, supported by governmental and industry based sources, which investigated the efficiency and effectiveness of procurement methods, organizational systems and management approaches to small works and minor maintenance projects. The findings indicate that management for small works must be exerted at two levels. One is within the organization of the works themselves. The second is the development of a framework and organization which considers the implication of the works upon the organization's ongoing business. Effective small works management requires that an organization responds promptly to an identified situation, determines the cost of the work, ensures that the work is undertaken successfully, and gives value for money within the context of the organization's current business circumstance.     

OPTIMAL MAINTENANCE SCHEDULING FOR WATER DISTRIBUTION SYSTEMS

The scheduling of maintenance for water distribution systems is a complex task encompassing a wide range of alternatives. The methodology presented in this paper can consider the major piping alternatives of replacing and cleaning, and relining. It also considers the potential of pumping improvements while accounting for the costs of maintenance, failure and operations for a multiple-period planning horizon. To solve the problem a nonlinear optimization model is linked with a network simulation model. The application showed that the procedure can determine solutions in reasonable times.     

Modeling of risk-based inspection,maintenance and life-cycle cost with partially observable Markov decision processes

The utilization of Markov decision processes as a sequential decision algorithm in the management actions of infrastructure (inspection, maintenance and repair) is discussed. The realistic issue of partial information from inspection is described, and the classic approach of partially observable Markov decision processes is then introduced. The use of this approach to determine optimal inspection strategies is described, as well as the role of deterioration and maintenance for steel structures. Discrete structural shapes and maintenance actions provide a tractable approach. In-service inspection incorporates Bayesian updating and leads to optimal operation and initial design. Finally, the concept of management policy is described with strategy vectors.