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Demand Pattern (demand + pattern)
Selected AbstractsHybrid Meta-Heuristic Algorithm for the Simultaneous Optimization of the O,D Trip Matrix EstimationCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2004Antony Stathopoulos These include a genetic algorithm (GA), a simulated annealing (SA) algorithm, and a hybrid algorithm (GASA) based on the combination of GA and SA. The computational performance of the three algorithms is evaluated and compared by implementing them on a realistic urban road network. The results of the simulation tests demonstrate that SA and GASA produce a more accurate final solution than GA, whereas GASA shows a superior convergence rate, that is, faster improvement from the initial solution, in comparison to SA and GA. In addition, GASA produces a final solution that is more robust and less dependent on the initial demand pattern, in comparison to that obtained from a greedy search algorithm. [source] Operating schedule of a combined energy network system with fuel cellINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2006S. ObaraArticle first published online: 16 MAY 200 Abstract The chromosome model showing system operation pattern is applied to GA (genetic algorithm), and the method of optimization operation planning of energy system is developed. The optimization method of this operation planning was applied to the compound system of methanol-steam-reforming-type fuel cell, geothermal heat pump and the electrolysis tank of water. The operation planning was performed for the energy system using the energy demand pattern of the individual residence of Sapporo city. From analysis results, the amount of outputs of a solar module and the relation of the operation cost of the system, which are changed by the weather were clarified. The representation day in February of the ratio of the operation cost in case of (0% of output rates) the rainy weather to the time of fine weather (100% of output rates) is 1.12. And the representation day in July is 1.71. Furthermore, the optimal capacity of accumulation of electricity and thermal storage was estimated, and they are 308 and 23 MJ, respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source] Resource allocation with lumpy demand: To speed or not to speed?NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 3 2004Bintong Chen Abstract In the classical EPQ model with continuous and constant demand, holding and setup costs are minimized when the production rate is no larger than the demand rate. However, the situation may change when demand is lumpy. We consider a firm that produces multiple products, each having a unique lumpy demand pattern. The decision involves determining both the lot size for each product and the allocation of resources for production rate improvements among the products. We find that each product's optimal production policy will take on only one of two forms: either continuous production or lot-for-lot production. The problem is then formulated as a nonlinear nonsmooth knapsack problem among products determined to be candidates for resource allocation. A heuristic procedure is developed to determine allocation amounts. The procedure decomposes the problem into a mixed integer program and a nonlinear convex resource allocation problem. Numerical tests suggest that the heuristic performs very well on average compared to the optimal solution. Both the model and the heuristic procedure can be extended to allow the company to simultaneously alter both the production rates and the incoming demand lot sizes through quantity discounts. Extensions can also be made to address the case where a single investment increases the production rate of multiple products. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004. [source] STOCK LEVELS AND DELIVERY RATES IN VENDORMANAGED INVENTORY PROGRAMSPRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2001BEN A. CHAOUCH Using the latest information technology, powerful retailers like Wal-Mart have taken the lead in forging shorter replenishment-cycles, automated supply systems with suppliers. With the objective to reduce cost, these retailers are directing suppliers to take full responsibility for managing stocks and deliveries. Suppliers' performance is measured according to how often inventory is shipped to the retailer, and how often customers are unable to purchase the product because it is out of stock. This emerging trend also implies that suppliers are absorbing a large part of the inventory and delivery costs and, therefore, must plan delivery programs including delivery frequency to ensure that the inherent costs are minimized. With the idea to incorporate this shift in focus, this paper looks at the problem facing the supplier who wants quicker replenishment at lower cost. In particular, we present a model that seeks the best trade-off among inventory investment, delivery rates, and permitting shortages to occur, given some random demand pattern for the product. The process generating demand consists of two components: one is deterministic and the other is random. The random part is assumed to follow a compound Poisson process. Furthermore, we assume that the supplier may fail to meet uniform shipping schedules, and, therefore, uncertainty is present in delivery times. The solution to this transportationinventory problem requires determining jointly delivery rates and stock levels that will minimize transportation, inventory, and shortage costs. Several numerical results are presented to give a feel of the optimal policy's general behavior. [source] Study of a fuel cell network with water electrolysis for improving partial load efficiency of a residential cogeneration systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2006S. Obara Abstract A fuel cell energy network which connects hydrogen and oxygen gas pipes, electric power lines and exhaust heat output lines of the fuel cell cogeneration for individual houses, respectively, is analysed. As an analysis case, the energy demand patterns of individual houses in Tokyo are used, and the analysis method for minimization of the operational cost using a genetic algorithm is described. The fuel cell network system of an analysis example assumed connecting the fuel cell cogeneration of five houses. If energy is supplied to the five houses using the fuel cell energy network proposed in this paper, 9% of city gas consumption will be reduced by the maximum from the results of analysis. Two per cent included with 9% is an effect of introducing water electrolysis operation of the fuel cells, corresponding to partial load operation of fuel cell cogeneration. Copyright © 2005 John Wiley & Sons, Ltd. [source] A review and synthesis of demand management, capacity management and performance in health-care servicesINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 2 2009Eric P. Jack Responses to demand uncertainty in the field of health-care services is a very timely research issue because of ongoing changes in demand patterns that are driven by demographics and recent changes in the delivery of these services. Despite its importance to researchers, the literature on demand management, capacity management and performance in health care has not been extensively reviewed. The present paper addresses this need by analyzing and synthesizing 463 articles published between 1986 and 2006. The key contributions of this work are the analysis and synthesis of research on demand management, capacity management and performance, along with an agenda to guide future research in this important area. [source] Global crisis and beyond: Sustainable growth trajectories for the developing worldINTERNATIONAL LABOUR REVIEW, Issue 2 2010Jayati GHOSH Abstract. Despite recent signs of output recovery, casual resumption of the growth model that crashed in 2008,09 will exacerbate the domestic and global imbalances that caused the crisis in the first place , to the detriment of the real economy, equitable development, and employment recovery. The model's environmental unsustainability is also evident. The author therefore argues for a broad policy agenda including reform of the international financial system, development strategies re-focused on wage-driven domestic demand and viable agriculture, fiscal promotion of greener technologies and demand patterns, and redistributive social policies to reduce inequalities and act as macroeconomic stabilizers in downturns. [source] Sustaining economic expansion in Pakistan in an era of energy shortfalls: growth options to 20351OPEC ENERGY REVIEW, Issue 2 2007Robert Looney Pakistan's recent economic acceleration together with rapid rates of population growth is having a significant impact on the country's energy supply/demand balances. Energy supplies in turn affect the pace and pattern of the country's economic expansion. Drawing on the empirically-based complex links between energy and the economy, several alternative scenarios of growth and energy needs are developed in an attempt to answer several key questions. In particular, what are some of the key interrelationships between sources of energy demand and supply? What are the economic growth consequences of alternative energy availabilities and, in turn, how do these growth patterns affect the subsequent energy supply and demand patterns? What energy strategies are suggested by the interconnection between the country growth requirements and energy needs? Are these significantly modified under rising or falling energy prices? Based on this analysis, several guidelines are drawn for the country's future energy policy. [source] | |||||||||||||