The Experts below are selected from a list of 3654 Experts worldwide ranked by ideXlab platform
Ek Peng Chew - One of the best experts on this subject based on the ideXlab platform.
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a container yard Storage Strategy for improving land utilization and operation efficiency in a transshipment hub port
European Journal of Operational Research, 2012Co-Authors: Xinjia Jiang, Ek Peng ChewAbstract:This paper studies the Storage yard management problem in a busy transshipment hub, where intense loading and unloading activities have to be considered at the same time. The need to handle huge volumes of container traffic and the scarcity of land in the container port area pose serious challenges for the port operator to provide efficient services. A consignment Strategy with a static yard template has been used to reduce the level of reshuffles in the yard, but it sacrifices on land utilization because of exclusive Storage space reservation. Two space-sharing approaches are proposed to improve on the land utilization through dynamic reservation of Storage space for different vessels during different shifts. Meanwhile, workload assignment among reserved spaces will also satisfy the high-low workload balancing protocol to reduce traffic congestion in the yard. A framework which integrates space reservation and workload assignment is proposed. Experimental results show that the framework is able to provide solutions for containers handling within much less Storage space, while guarantee the least yard crane deployment.
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a yard Storage Strategy for minimizing traffic congestion in a marine container transshipment hub
OR Spectrum, 2008Co-Authors: Ek Peng ChewAbstract:This paper studies a Storage yard management problem in a transshipment hub where the loading and unloading activities are both heavy and concentrated. In order to reduce the number of reshuffles, which helps to reduce the vessel turnaround time, the port operator uses the consignment Strategy to group export and transshipment containers according to their destination vessel. To reduce the potential traffic congestion of prime movers, a high–low workload balancing protocol is used. A mixed integer programming model is formulated to determine the Storage locations of incoming containers, the number of incoming containers and the smallest number of yard cranes to deploy in each shift. An iterative improvement method is developed to solve the problem, in which a tabu search based heuristic algorithm is used to generate an initial yard template, and then the generated yard template is improved by an improvement algorithm iteratively until an optimal or a satisfactory solution is obtained. Experiment results show that the proposed method can generate excellent results within a reasonable time, even for the extreme cases.
R B M De Koster - One of the best experts on this subject based on the ideXlab platform.
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travel distance estimation and Storage zone optimization in a 2 block class based Storage Strategy warehouse
International Journal of Production Research, 2005Co-Authors: Tho Leduc, R B M De KosterAbstract:Order picking has been considered as the most critical operation in warehousing. Recent trends in logistics demand faster but more reliable order picking systems. The efficiency of an order picking process greatly depends on the Storage policy used, i.e. where products are located within the warehouse. In this paper, we deal with the most popular Storage policy that is class-based (or ABC) Storage Strategy. Particularly, we investigate the problem of determining the optimal Storage boundaries (zones) of classes in each aisle for manually operated warehouses. We first propose a probabilistic model that enables us to estimate the average travel distance of a picking tour. We found that the differences between results obtained from simulation and the model were slight. Using the average travel distance as the objective function, we present a mathematical formulation for the Storage zone optimization problem. However, the exact approach can handle only small size warehouse instances. To circumvent this obstac...
Xinjia Jiang - One of the best experts on this subject based on the ideXlab platform.
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a container yard Storage Strategy for improving land utilization and operation efficiency in a transshipment hub port
European Journal of Operational Research, 2012Co-Authors: Xinjia Jiang, Ek Peng ChewAbstract:This paper studies the Storage yard management problem in a busy transshipment hub, where intense loading and unloading activities have to be considered at the same time. The need to handle huge volumes of container traffic and the scarcity of land in the container port area pose serious challenges for the port operator to provide efficient services. A consignment Strategy with a static yard template has been used to reduce the level of reshuffles in the yard, but it sacrifices on land utilization because of exclusive Storage space reservation. Two space-sharing approaches are proposed to improve on the land utilization through dynamic reservation of Storage space for different vessels during different shifts. Meanwhile, workload assignment among reserved spaces will also satisfy the high-low workload balancing protocol to reduce traffic congestion in the yard. A framework which integrates space reservation and workload assignment is proposed. Experimental results show that the framework is able to provide solutions for containers handling within much less Storage space, while guarantee the least yard crane deployment.
Albert Y. Zomaya - One of the best experts on this subject based on the ideXlab platform.
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Shadow-Chain: A Decentralized Storage System for Log Data
IEEE Network, 2020Co-Authors: Feng Lu, Wei Li, Albert Y. ZomayaAbstract:Better use of personal health and clinical data from different stakeholders is essential and highly significant. However, the sharing of such data could easily raise concerns over preserving personal privacy, particularly when the risk of disclosure is uncertain. To tackle this issue, shadow- chain, a decentralized Storage system for log data based on blockchain, is proposed for realizing data sharing between parties that do not trust each other. In the system, a behavior monitor is designed to intercept the data reading activities. Through an asynchronous read-write mechanism, the monitor can minimize operational impact on the source's Storage system. Meanwhile, the homomorphic encryption scheme and the distributed log collection system are adopted to guarantee the validity and reliability of the log data. Furthermore, the hybrid Storage Strategy is developed to reduce the Storage overhead of the log data. In the Strategy, only the hash of log data is stored in the blockchain of the shadow-chain, while the data itself and the associated index information are placed in common Storage media. Experiments have been conducted to estimate the performance of our shadow-chain. The results show that the impact of shadow-chain on the source Storage system can be controlled within 5 percent, and 75 percent log Storage overhead can be reduced through hybrid Storage Strategy.
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An Energy-Efficient Storage Strategy for Cloud Datacenters Based on Variable K-Coverage of a Hypergraph
IEEE Transactions on Parallel and Distributed Systems, 2017Co-Authors: Ting Yang, Wei Li, Dong Yuan, Albert Y. ZomayaAbstract:Distributed Storage systems, e.g., Hadoop Distributed File System (HDFS), have been widely used in datacenters for handling large amounts of data due to their excellent performance in terms of fault tolerance, reliability and scalability. However, these Storage systems usually adopt the same replication and Storage Strategy to guarantee data availability, i.e., creating the same number of replicas for all data sets and randomly storing them across data nodes. Such strategies do not fully consider the difference requirements of data availability on different data sets. More servers than necessary should thus be used to store replicas of rarely-used data, which will lead to increased energy consumption. To address this issue, we propose an energy-efficient Storage Strategy for cloud datacenters based on a novel hypergraph coverage model. According to users' requirements of data availability in different applications, our proposed algorithm can selectively determine the corresponding minimum hyperedge coverage, which represents the minimum set of data nodes required in the datacenter. Hence, some other data nodes can be turned off for the purpose of energy saving. We have also implemented our proposed algorithm as a dynamic runtime Strategy in a HDFS based prototype datacenter for performance evaluation. Experimental results show that the variable hypergraph coverage based Strategy can not only reduce energy consumption, but can also improve the network performance in the datacenter.
Tho Leduc - One of the best experts on this subject based on the ideXlab platform.
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travel distance estimation and Storage zone optimization in a 2 block class based Storage Strategy warehouse
International Journal of Production Research, 2005Co-Authors: Tho Leduc, R B M De KosterAbstract:Order picking has been considered as the most critical operation in warehousing. Recent trends in logistics demand faster but more reliable order picking systems. The efficiency of an order picking process greatly depends on the Storage policy used, i.e. where products are located within the warehouse. In this paper, we deal with the most popular Storage policy that is class-based (or ABC) Storage Strategy. Particularly, we investigate the problem of determining the optimal Storage boundaries (zones) of classes in each aisle for manually operated warehouses. We first propose a probabilistic model that enables us to estimate the average travel distance of a picking tour. We found that the differences between results obtained from simulation and the model were slight. Using the average travel distance as the objective function, we present a mathematical formulation for the Storage zone optimization problem. However, the exact approach can handle only small size warehouse instances. To circumvent this obstac...
