This article analyzes a continuous-review inventory system with random supply interruptions and random lead time which may be interrupted by a random number of supplier’s OFF periods. The inventory with constant dema...This article analyzes a continuous-review inventory system with random supply interruptions and random lead time which may be interrupted by a random number of supplier’s OFF periods. The inventory with constant demand rate is managed by a （r; q1, q2, · · · , qm） policy and supplies from an unreliable sole supplier. By renewal theory and matrix Geometric method, the long-run average cost function is obtained and some important properties of the function are proved. Furthermore, performance of the inventory is derived.展开更多
Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effec...Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.展开更多
In this work, the dynamics of networked goods distribution systems subject to the control of a continuous-review order-up-to inventory policy are investigated. In the analytical study, as opposed to the earlier models...In this work, the dynamics of networked goods distribution systems subject to the control of a continuous-review order-up-to inventory policy are investigated. In the analytical study, as opposed to the earlier models constrained to the serial and arborescent interconnection structures, an arbitrary multiechelon topology is considered. This external, uncertain demand,following any distribution, may be imposed on all network nodes,not just conveniently selected contact points. As in the physical systems, stock relocation to refill the reserves is subject to nonnegligible delay, which poses a severe stability threat and may lead to cost-inefficient decisions. A state-space model is created and used as the framework for analyzing system properties. In particular, it is formally demonstrated that despite unpredictable demand fluctuations, a feasible(nonnegative and bounded)reserves replenishment signal is generated at all times, and the stock gathered at the nodes does not surpass a finite, precisely determined level. The theoretical content is illustrated with a case study of the Chinese oil supply system.展开更多
A replenishment decision-making model for supply-hub is firstly established from the angle of supplier, and optimal replenishment decision of the supplier is analyzed. Then, inventory optimization model for supply-hub...A replenishment decision-making model for supply-hub is firstly established from the angle of supplier, and optimal replenishment decision of the supplier is analyzed. Then, inventory optimization model for supply-hub is formulated from the angle of the manufacturer, and the optimization algorithm for obtaining optimal inventory levels is given. The result shows that liability period decides the share of the inventory cost between two sides in supply chain. With the increase of liability period, the service level has been quickly reduced even though the manufacturer's cost has been cut down by transferring the inventory cost to the supplier. As to the safety inventory, if the lower bound of components safety inventory increases, the supplier's cost will rise up more slowly than the liability period does, while the service levels increases as the safety inventory's lower bound is raised.展开更多
In spare parts industries, firms are dealing with a situation which is more and more uncertain due to the supply chain structure and variable demands. This paper presents a Bayesian approach to forecast demand and sub...In spare parts industries, firms are dealing with a situation which is more and more uncertain due to the supply chain structure and variable demands. This paper presents a Bayesian approach to forecast demand and subsequently determine the appropriate parameter S of an （ S - 1 ; S） inventory system for controlling plant spare parts. We apply the Bayesian approach in an innovative way to specify the initial prior distributions of the failure rates, using the initial estimates and the failure history of similar items. According to the proposed method, a lower base stock than the one currently used is sufficient to achieve the desired service level.展开更多
The Petri Net Pareto method proposed in this study has the advantages of acting directly on computing results by assessment of workflow process information. Our study contributes to the literature because it has inves...The Petri Net Pareto method proposed in this study has the advantages of acting directly on computing results by assessment of workflow process information. Our study contributes to the literature because it has investigated an ISO 31000 workflow process approach to group decision making for reducing backorders in the supply chain, from an integrated perspective utilizing Pareto charts and Petri nets. The contribution to the literature is also enhanced by the L-Project illustrative example that presents an evaluation hierarchy of supply chain risk. The proposed method is appropriate for use in situations in which assessment information may be qualitative or precise quantitative information is either unavailable or too costly to compute.展开更多
目的:构建适用于不确定环境下的应急物资分级库存模型,以为传染病暴发后的应急响应提供更准确和有效的决策支持。方法:首先,使用“之”字形不确定分布构建应急物资分级模型;其次,将经济订购量(economic order quantity,EOQ)模型与应急...目的:构建适用于不确定环境下的应急物资分级库存模型,以为传染病暴发后的应急响应提供更准确和有效的决策支持。方法:首先,使用“之”字形不确定分布构建应急物资分级模型;其次,将经济订购量(economic order quantity,EOQ)模型与应急物资分级模型相结合构建应急物资分级库存模型;最后,以W市某次急性呼吸道传染病事件为例,验证提出的应急物资分级库存模型的实用性和有效性。结果:该模型在大部分情况下能够准确地对应急物资进行分级,且以该模型计算得到的库存量十分接近需求量。结论:建立的应急物资分级库存模型在急性呼吸道传染病的应急响应中具有实用性和有效性,可以帮助决策者更准确地预测应急物资的需求,提高应急响应的能力和效率。展开更多
Air pollution from shipping is becoming a critical issue,particularly in dense hub port cities.One proposed solution to minimize ship-based emissions at ports is the implementation of an Onshore Power Supply(OPS)syste...Air pollution from shipping is becoming a critical issue,particularly in dense hub port cities.One proposed solution to minimize ship-based emissions at ports is the implementation of an Onshore Power Supply(OPS)system.OPS allows ships to shut off their auxiliary engines and instead connect to the port grid.While there have been numerous studies conducted on ports in Europe and the United States,little research has been done on Egyptian ports.Therefore,this paper aims to investigate the feasibility of implementing OPS at Port Said West Port in Egypt,aligning with Egypt Vision 2030’s goals for addressing climate change.The research primarily focuses on analyzing data collected from calling ships to generate socio-economic and cost-effectiveness analyses of OPS.To further enhance the environmental benefits of OPS,the paper proposes the use of solar energy as the OPS electricity source.The findings of the study revealed that by relying on the national grid,emissions can be reduced by 28%.Moreover,it is predicted that this reduction could reach 100%if electricity generation is solely based on solar energy.Additionally,the economic analysis demonstrates promising profitability,with a payback period of approximately two years.展开更多
基金supported by the National Natural Science Foundation of China (71071134 and 71001073)funds by Hebei Science and Technology Research and Development Program (10457202D-3)2010 Social Development of Research Subject of Hebei Province(201005006)
文摘This article analyzes a continuous-review inventory system with random supply interruptions and random lead time which may be interrupted by a random number of supplier’s OFF periods. The inventory with constant demand rate is managed by a （r; q1, q2, · · · , qm） policy and supplies from an unreliable sole supplier. By renewal theory and matrix Geometric method, the long-run average cost function is obtained and some important properties of the function are proved. Furthermore, performance of the inventory is derived.
文摘Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.
文摘In this work, the dynamics of networked goods distribution systems subject to the control of a continuous-review order-up-to inventory policy are investigated. In the analytical study, as opposed to the earlier models constrained to the serial and arborescent interconnection structures, an arbitrary multiechelon topology is considered. This external, uncertain demand,following any distribution, may be imposed on all network nodes,not just conveniently selected contact points. As in the physical systems, stock relocation to refill the reserves is subject to nonnegligible delay, which poses a severe stability threat and may lead to cost-inefficient decisions. A state-space model is created and used as the framework for analyzing system properties. In particular, it is formally demonstrated that despite unpredictable demand fluctuations, a feasible(nonnegative and bounded)reserves replenishment signal is generated at all times, and the stock gathered at the nodes does not surpass a finite, precisely determined level. The theoretical content is illustrated with a case study of the Chinese oil supply system.
基金Projects(71102174,70971036) supported by the National Natural Science Foundation of ChinaProject(9123028) supported by the Beijing Natural Science Foundation,China+3 种基金Project(20111101120019) supported by the Specialized Research Fund for Doctoral Program of Higher Education of ChinaProject(11JGC106) supported by the Beijing Philosophy&Social Science Foundation of ChinaProjects(NCET-10-0048,NCET-10-0043) supported by the Program for New Century Excellent Talents in Universities of ChinaProject(2010YC1307) supported by the Excellent Young Teacher in Beijing Institute of Technology of China
文摘A replenishment decision-making model for supply-hub is firstly established from the angle of supplier, and optimal replenishment decision of the supplier is analyzed. Then, inventory optimization model for supply-hub is formulated from the angle of the manufacturer, and the optimization algorithm for obtaining optimal inventory levels is given. The result shows that liability period decides the share of the inventory cost between two sides in supply chain. With the increase of liability period, the service level has been quickly reduced even though the manufacturer's cost has been cut down by transferring the inventory cost to the supplier. As to the safety inventory, if the lower bound of components safety inventory increases, the supplier's cost will rise up more slowly than the liability period does, while the service levels increases as the safety inventory's lower bound is raised.
文摘In spare parts industries, firms are dealing with a situation which is more and more uncertain due to the supply chain structure and variable demands. This paper presents a Bayesian approach to forecast demand and subsequently determine the appropriate parameter S of an （ S - 1 ; S） inventory system for controlling plant spare parts. We apply the Bayesian approach in an innovative way to specify the initial prior distributions of the failure rates, using the initial estimates and the failure history of similar items. According to the proposed method, a lower base stock than the one currently used is sufficient to achieve the desired service level.
文摘The Petri Net Pareto method proposed in this study has the advantages of acting directly on computing results by assessment of workflow process information. Our study contributes to the literature because it has investigated an ISO 31000 workflow process approach to group decision making for reducing backorders in the supply chain, from an integrated perspective utilizing Pareto charts and Petri nets. The contribution to the literature is also enhanced by the L-Project illustrative example that presents an evaluation hierarchy of supply chain risk. The proposed method is appropriate for use in situations in which assessment information may be qualitative or precise quantitative information is either unavailable or too costly to compute.
文摘目的:构建适用于不确定环境下的应急物资分级库存模型,以为传染病暴发后的应急响应提供更准确和有效的决策支持。方法:首先,使用“之”字形不确定分布构建应急物资分级模型;其次,将经济订购量(economic order quantity,EOQ)模型与应急物资分级模型相结合构建应急物资分级库存模型;最后,以W市某次急性呼吸道传染病事件为例,验证提出的应急物资分级库存模型的实用性和有效性。结果:该模型在大部分情况下能够准确地对应急物资进行分级,且以该模型计算得到的库存量十分接近需求量。结论:建立的应急物资分级库存模型在急性呼吸道传染病的应急响应中具有实用性和有效性,可以帮助决策者更准确地预测应急物资的需求,提高应急响应的能力和效率。
文摘Air pollution from shipping is becoming a critical issue,particularly in dense hub port cities.One proposed solution to minimize ship-based emissions at ports is the implementation of an Onshore Power Supply(OPS)system.OPS allows ships to shut off their auxiliary engines and instead connect to the port grid.While there have been numerous studies conducted on ports in Europe and the United States,little research has been done on Egyptian ports.Therefore,this paper aims to investigate the feasibility of implementing OPS at Port Said West Port in Egypt,aligning with Egypt Vision 2030’s goals for addressing climate change.The research primarily focuses on analyzing data collected from calling ships to generate socio-economic and cost-effectiveness analyses of OPS.To further enhance the environmental benefits of OPS,the paper proposes the use of solar energy as the OPS electricity source.The findings of the study revealed that by relying on the national grid,emissions can be reduced by 28%.Moreover,it is predicted that this reduction could reach 100%if electricity generation is solely based on solar energy.Additionally,the economic analysis demonstrates promising profitability,with a payback period of approximately two years.
