The Experts below are selected from a list of 5409 Experts worldwide ranked by ideXlab platform

Wei Xiang - One of the best experts on this subject based on the ideXlab platform.

  • Analysis on Real-Time Control Channel and the Construction of Emergency Channel
    DEStech Transactions on Computer Science and Engineering, 2018
    Co-Authors: Wei Xiang
    Abstract:

    The real-time control Channel plays an important role in power communication system. Taking the average interruption time of the Channel as production index by China Southern Power Grid indicates that power system has higher requirements on communication service ability. In order to reduce influence of node failure from power communication network, the weak links should be improved. In this paper, the statuses of the real-time controlling Channel are analyzed, and it also proposed configuration and using method of Emergency Channel. It improves the rapid recovery ability, and meets the requirement of assessment indicators.

Huang Shi-y - One of the best experts on this subject based on the ideXlab platform.

Genaro J. Gutierrez - One of the best experts on this subject based on the ideXlab platform.

  • A periodic review inventory system with two supply modes
    European Journal of Operational Research, 1996
    Co-Authors: Chi Chiang, Genaro J. Gutierrez
    Abstract:

    Abstract We describe a periodic review inventory system in which there are two modes of resupply, namely a regular mode and an Emergency mode. Orders placed through the Emergency Channel have a shorter supply lead time but are subject to higher ordering costs compared to orders placed through the regular Channel. We analyze this problem within the framework of an order-up-to-R inventory control policy. At each epoch, the inventory manager must decide which of the two supply modes to use and then order enough units to raise the inventory position to a level R. We show that given any non-negative order-up-to level, either only the regular supply mode is used, or there exists an indifference inventory level such that if the inventory position at the review epoch is below the indifference inventory level, the Emergency supply mode is used. We also develop procedures for solving for the two policy parameters, i.e., the order-up-to level and the indifference inventory level.

Van Gjjan Geert-jan Houtum - One of the best experts on this subject based on the ideXlab platform.

  • Approximate evaluation of order fill rates for an inventory system of service tools
    International Journal of Production Economics, 2009
    Co-Authors: Imh Ingrid Vliegen, Van Gjjan Geert-jan Houtum
    Abstract:

    This paper deals with the analysis of a single-location, multi-item inventory model for service tools, in which coupled demands and coupled returns occur. We distinguish multiple Poisson demand streams. Per stream there is a given set of tools that is requested per demand. We are interested in the order fill rates, i.e., the percentage of demands for which all requested tools are delivered from stock. Requested tools that are not on stock are delivered via an Emergency Channel. For the warehouse under consideration, they may be considered as lost sales. Delivered tools are returned to the warehouse after a deterministic return time, that is equal for all tools. We show that the full multi-item evaluation problem decomposes into evaluation problems for small sets of service tools. For the resulting subproblems, we develop three approximate models for the order fill rates, which are all based on Markovian models. One approximate model has appeared to give an underestimation in all computational tests, while the second approximate model has led to an overestimation in all instances tested. The last approximate model combines the other two. This approximate model is very accurate and can be computed efficiently for representative instances based on data from an Original Equipment Manufacturer with whom we collaborated for this research.

  • Evaluation of a multi-item inventory system with coupled arrivals and returns
    2006
    Co-Authors: Imh Ingrid Vliegen, Van Gjjan Geert-jan Houtum
    Abstract:

    This paper deals with the analysis of a single-location, multi-item inventory model for service tools, in which coupled arrivals and coupled returns occur. We distinguish multiple Poisson demand streams. Per stream there is a given set of tools that is requested per demand. We are interested in the order fill rates, i.e., the percentage of demands for which all requested tools are delivered from stock. Requested tools that are not on stock, are delivered via an Emergency Channel. For the warehouse under consideration, they may be considered as lost sales. Delivered tools are returned to the warehouse after a deterministic return time, that is equal for all tools. We develop two approximations for the order fill rates, which are both based on Markovian models. One approximation has appeared to give an underestimation in all computational tests, while the other approximation had led to an overestimation in all instances tested. Furthermore, the approximations are reasonably accurate and can be computed efficiently. Hence, they are appropriate for usage in multi-item optimization algorithms.

George Tagaras - One of the best experts on this subject based on the ideXlab platform.

  • An inventory system with two supply modes and capacity constraints
    International Journal of Production Economics, 2001
    Co-Authors: Dimitrios Vlachos, George Tagaras
    Abstract:

    Abstract This paper analyses a periodic review inventory system with a main and an Emergency supply mode, where policies of the base-stock type are used at both supply Channels. Contrary to previously published models, the capacity of the Emergency Channel is taken into account. We examine two alternative ordering policies for that Channel: an “early-ordering” policy that almost eliminates early stockouts in a replenishment cycle and a “late-ordering” policy that delays the Emergency order decision until more demand information has been accumulated. Approximate cost models are developed and properties of their optimal solutions are derived. Simulation results indicate that these solutions are near optimal. Conclusions are drawn about the relative effectiveness of the two Emergency ordering policies.