Industry 4.0 and Cyber Physical Production Systems (CPPS) are often discussed and partially already sold. One important feature of CPPS is fault tolerance and as a consequence self-configuration and restart to increas...Industry 4.0 and Cyber Physical Production Systems (CPPS) are often discussed and partially already sold. One important feature of CPPS is fault tolerance and as a consequence self-configuration and restart to increase Overall Equipment Effectiveness. To understand this challenge at first the state of the art of fault handling in industrial automated production systems (aPS) is discussed as a result of a case study analysis in eight companies developing aPS. In the next step, metrics to evaluate the concept of self-configuration and restart for aPS focusing on real-time capabilities, fault coverage and effort to increase fault coverage are proposed. Finally, two different lab size case studies prove the applicability of the concepts of self-configuration, restart and the proposed metrics.展开更多
As a key to improve the performance of the interbay automated material handling system （AMHS） in 300 mm semiconductor wafer fabrication system, the real- time overhead hoist transport （OHT） dispatching problem has...As a key to improve the performance of the interbay automated material handling system （AMHS） in 300 mm semiconductor wafer fabrication system, the real- time overhead hoist transport （OHT） dispatching problem has received much attention. This problem is first formu- lated as a special form of assignment problem and it is proved that more than one solution will be obtained by Hungarian algorithm simultaneously. Through proposing and strictly proving two propositions related to the char- acteristics of these solutions, a modified Hungarian algo- rithm is designed to distinguish these solutions. Finally, a new real-time OHT dispatching method is carefully designed by implementing the solution obtained by the modified Hungarian algorithm. The experimental results of discrete event simulations show that, compared with con- ventional Hungarian algorithm dispatching method, the proposed dispatching method that chooses the solution with the maximum variance respectively reduces on average 4 s of the average waiting time and average lead time of wafer lots, and its performance is rather stable in multiple dif- ferent scenarios of the interbay AMHS with different quantities of shortcuts. This research provides an efficient real-time OHT dispatching mechanism for the interbay AMHS with shortcuts and bypasses.展开更多
A cross-sectional study was carried out to assess hygienic production and postharvest handling practices of raw camel milk in Degahbour district. The survey studies were based on a total of 120 (2 production systems *...A cross-sectional study was carried out to assess hygienic production and postharvest handling practices of raw camel milk in Degahbour district. The survey studies were based on a total of 120 (2 production systems * 2 rural kebele * 30 households) milk producers, which were selected from Degahbur district using stratified sampling technique. Data from the selected producers were collected using questionnaire survey and field observation. The results showed that the majority of the sampled household heads in pastoral (93.3%) and agro-pastoral (76.6%) production systems were illiterate. Moreover, none of the respondents in the study area had training on hygienic milk production and postharvest handling practices. The study result also indicated that none of the respondents in the study area washed the udder of milking camel before milking. Moreover, only 6.6% of pastoralists and 25% of agro-pastoralists wash their hands before milking. Equipment made of wooden materials are mainly used for milking, whereas, plastic jerry-cans were most commonly used for storage. About 45% of the pastoralists and 81.6% of the agro-pastoralists were cleaning milk vessels regularly;however, majority of the respondents both production systems were using water from non-tap sources for hygienic practices. Bosciaminimifolia, Acacia ethaica and Blanitesgalabra were the most commonly used plant species for smoking in the study area. Therefore, hygienic production and postharvest handling practices should be followed to improve the quality and suitability of camel milk for its intended use in the study area.展开更多
This paper proposes the use of Group Method of Data Handling (GMDH) technique for modeling Magneto-Rheological (MR) dampers in the context of system identification. GMDH is a multilayer network of quadratic neurons th...This paper proposes the use of Group Method of Data Handling (GMDH) technique for modeling Magneto-Rheological (MR) dampers in the context of system identification. GMDH is a multilayer network of quadratic neurons that offers an effective solution to modeling non-linear systems. As such, we propose the use of GMDH to approximate the forward and inverse dynamic behaviors of MR dampers. We also introduce two enhanced GMDH-based solutions. Firstly, a two-tier architecture is proposed whereby an enhanced GMD model is generated by the aid of a feedback scheme. Secondly, stepwise regression is used as a feature selection method prior to GMDH modeling. The proposed enhancements to GMDH are found to offer improved prediction results in terms of reducing the root-mean-squared error by around 40%.展开更多
在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组...在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组再有一个副本所在的硬盘发生故障,将导致系统无法继续提供服务,且不能自动恢复.本文提出一种基于日志副本的改进的Raft共识算法,即LR-Raft (log replica based Raft),日志副本没有完整状态机,可以快速加入集群,并参与投票与共识,提升了存在故障硬盘时系统的可用性;可以解决短时间内三副本中两个副本故障导致集群不可用和丢失数据的问题.实验结果表明,在副本组中引入日志副本后,与原Raft相比,LR-Raft在不同的工作负载下读写时延均明显降低,吞吐量显著提升.展开更多
文摘Industry 4.0 and Cyber Physical Production Systems (CPPS) are often discussed and partially already sold. One important feature of CPPS is fault tolerance and as a consequence self-configuration and restart to increase Overall Equipment Effectiveness. To understand this challenge at first the state of the art of fault handling in industrial automated production systems (aPS) is discussed as a result of a case study analysis in eight companies developing aPS. In the next step, metrics to evaluate the concept of self-configuration and restart for aPS focusing on real-time capabilities, fault coverage and effort to increase fault coverage are proposed. Finally, two different lab size case studies prove the applicability of the concepts of self-configuration, restart and the proposed metrics.
基金Supported by National Natural Science Foundation of China(Grant No.51275307)
文摘As a key to improve the performance of the interbay automated material handling system （AMHS） in 300 mm semiconductor wafer fabrication system, the real- time overhead hoist transport （OHT） dispatching problem has received much attention. This problem is first formu- lated as a special form of assignment problem and it is proved that more than one solution will be obtained by Hungarian algorithm simultaneously. Through proposing and strictly proving two propositions related to the char- acteristics of these solutions, a modified Hungarian algo- rithm is designed to distinguish these solutions. Finally, a new real-time OHT dispatching method is carefully designed by implementing the solution obtained by the modified Hungarian algorithm. The experimental results of discrete event simulations show that, compared with con- ventional Hungarian algorithm dispatching method, the proposed dispatching method that chooses the solution with the maximum variance respectively reduces on average 4 s of the average waiting time and average lead time of wafer lots, and its performance is rather stable in multiple dif- ferent scenarios of the interbay AMHS with different quantities of shortcuts. This research provides an efficient real-time OHT dispatching mechanism for the interbay AMHS with shortcuts and bypasses.
基金supported by National Basic Research Program of China(973Program)(2012CB720000)National Natural Science Foundation of China(61225015,61273128)+2 种基金Foundation for Innovative Research Groups of the National Natural Science Foundation of China(61321002)the Ph.D.Programs Foundation of Ministry of Education of China(20111101110012)CAST Foundation(CAST201210)
文摘A cross-sectional study was carried out to assess hygienic production and postharvest handling practices of raw camel milk in Degahbour district. The survey studies were based on a total of 120 (2 production systems * 2 rural kebele * 30 households) milk producers, which were selected from Degahbur district using stratified sampling technique. Data from the selected producers were collected using questionnaire survey and field observation. The results showed that the majority of the sampled household heads in pastoral (93.3%) and agro-pastoral (76.6%) production systems were illiterate. Moreover, none of the respondents in the study area had training on hygienic milk production and postharvest handling practices. The study result also indicated that none of the respondents in the study area washed the udder of milking camel before milking. Moreover, only 6.6% of pastoralists and 25% of agro-pastoralists wash their hands before milking. Equipment made of wooden materials are mainly used for milking, whereas, plastic jerry-cans were most commonly used for storage. About 45% of the pastoralists and 81.6% of the agro-pastoralists were cleaning milk vessels regularly;however, majority of the respondents both production systems were using water from non-tap sources for hygienic practices. Bosciaminimifolia, Acacia ethaica and Blanitesgalabra were the most commonly used plant species for smoking in the study area. Therefore, hygienic production and postharvest handling practices should be followed to improve the quality and suitability of camel milk for its intended use in the study area.
文摘This paper proposes the use of Group Method of Data Handling (GMDH) technique for modeling Magneto-Rheological (MR) dampers in the context of system identification. GMDH is a multilayer network of quadratic neurons that offers an effective solution to modeling non-linear systems. As such, we propose the use of GMDH to approximate the forward and inverse dynamic behaviors of MR dampers. We also introduce two enhanced GMDH-based solutions. Firstly, a two-tier architecture is proposed whereby an enhanced GMD model is generated by the aid of a feedback scheme. Secondly, stepwise regression is used as a feature selection method prior to GMDH modeling. The proposed enhancements to GMDH are found to offer improved prediction results in terms of reducing the root-mean-squared error by around 40%.
文摘在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组再有一个副本所在的硬盘发生故障,将导致系统无法继续提供服务,且不能自动恢复.本文提出一种基于日志副本的改进的Raft共识算法,即LR-Raft (log replica based Raft),日志副本没有完整状态机,可以快速加入集群,并参与投票与共识,提升了存在故障硬盘时系统的可用性;可以解决短时间内三副本中两个副本故障导致集群不可用和丢失数据的问题.实验结果表明,在副本组中引入日志副本后,与原Raft相比,LR-Raft在不同的工作负载下读写时延均明显降低,吞吐量显著提升.
