Multi-period heat exchanger network(HEN) retrofit is usually performed by targeting and matching heat transfer areas. In this paper, based on the reverse order matching method we proposed previously, three strategies ...Multi-period heat exchanger network(HEN) retrofit is usually performed by targeting and matching heat transfer areas. In this paper, based on the reverse order matching method we proposed previously, three strategies of matching heat transfer areas are proposed to minimize the investment cost for the retrofit of HEN in multiperiod, in which replacement of heat exchangers, addition of heat exchangers and addition of heat transfer areas are performed. We demonstrate the procedures through three scenarios, including maximum number of substituted heat exchangers after retrofit, minimum additional heat transfer areas in the retrofitted HEN, and minimum investment cost for retrofit. The strategies are extended to a single period HEN retrofit problem. The results of multi-period and single period HEN retro fit problems indicate the effectiveness of the strategies. Moreover, these results are better than those reported in literature. The strategies are simple and easy to implement,which are of great benefit to large-scale HEN retrofit in practice.展开更多
This article explores the problematic status of reality before and after Holocaust. Taking two different Polish novels as examples, the author deals with the metaphor of ruins, remains, and ashes to define the ontolog...This article explores the problematic status of reality before and after Holocaust. Taking two different Polish novels as examples, the author deals with the metaphor of ruins, remains, and ashes to define the ontological status of the world in two texts. In the first text, Piotr Szewc＇s annihilation brings the positive vision of ruin as a kind of fragile and finite being which needs love and care. In the second text, Piotr Pazinski＇s Pensjonat shows that ruin is only a negative aspect of reality which is illegible and empty. The main concern of the text is to oppose those two visions and make a conclusion about the dialectic of the ruin.展开更多
This paper investigated the interaction effects between inventory and transportation strategies in the logistics network. Demand volumes and shipping sizes were simulated as part of a new conceptual model using a disc...This paper investigated the interaction effects between inventory and transportation strategies in the logistics network. Demand volumes and shipping sizes were simulated as part of a new conceptual model using a discrete event simulation by minimizing the total logistics cost in the supply chain. The experiments indicate that the full truckload scenario leads to cost efficiency and the larger demand size results in smaller cost per unit based on economies of scale. Considering the interaction effects, demand size has a greater impact on cost reduction than shipping size. The total logistics cost in the system is dependent on replenishment rate and flow rates from the higher to the lower echelon. High inventory cost is the result of a fast replenishment rate and frequent orders, while shipping cost is dependent on the flow rates in a process and total travelling time or total travelling distance. Shipping size also has an impact on the level of service and the total cost along with effective order variability.展开更多
This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and di...This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and disruptive technologies, utilizing the concept of low cost manufacturing and operating modes as well. This paper also analyzes the launch strategies for small satellites such as piggyback, networking launch, and single launch with a small launch vehicle(SLV). Finally, the development trend of reusable launch vehicles is discussed as well as the development prospects for China's reusable launch vehicle.展开更多
This paper considers a buyer＇s procuring strategy where the buyer purchases products from a supplier in order to minimize his total cost. Assume that the customer arrivals follow a Poisson process, a base-stock polic...This paper considers a buyer＇s procuring strategy where the buyer purchases products from a supplier in order to minimize his total cost. Assume that the customer arrivals follow a Poisson process, a base-stock policy is implemented by the buyer, and the supplier will afford partial operating cost incurred by the buyer; The cost shared by the buyer includes procuring cost and some operating cost; The supplier does not hold the inventory and her production time is exponentially distributed. The objective of the supplier is to maximize her profit. The buyer designs a contract to minimize his total expected cost. Two different cases are considered： One potential supplier and many competing suppliers. The optimal control approaches are used to design the buyer＇s optimal mechanism and some simple procurement mechanisms are presented.展开更多
基金Supported by the National Natural Science Foundation of China(21376188,21176198)
文摘Multi-period heat exchanger network(HEN) retrofit is usually performed by targeting and matching heat transfer areas. In this paper, based on the reverse order matching method we proposed previously, three strategies of matching heat transfer areas are proposed to minimize the investment cost for the retrofit of HEN in multiperiod, in which replacement of heat exchangers, addition of heat exchangers and addition of heat transfer areas are performed. We demonstrate the procedures through three scenarios, including maximum number of substituted heat exchangers after retrofit, minimum additional heat transfer areas in the retrofitted HEN, and minimum investment cost for retrofit. The strategies are extended to a single period HEN retrofit problem. The results of multi-period and single period HEN retro fit problems indicate the effectiveness of the strategies. Moreover, these results are better than those reported in literature. The strategies are simple and easy to implement,which are of great benefit to large-scale HEN retrofit in practice.
文摘This article explores the problematic status of reality before and after Holocaust. Taking two different Polish novels as examples, the author deals with the metaphor of ruins, remains, and ashes to define the ontological status of the world in two texts. In the first text, Piotr Szewc＇s annihilation brings the positive vision of ruin as a kind of fragile and finite being which needs love and care. In the second text, Piotr Pazinski＇s Pensjonat shows that ruin is only a negative aspect of reality which is illegible and empty. The main concern of the text is to oppose those two visions and make a conclusion about the dialectic of the ruin.
文摘This paper investigated the interaction effects between inventory and transportation strategies in the logistics network. Demand volumes and shipping sizes were simulated as part of a new conceptual model using a discrete event simulation by minimizing the total logistics cost in the supply chain. The experiments indicate that the full truckload scenario leads to cost efficiency and the larger demand size results in smaller cost per unit based on economies of scale. Considering the interaction effects, demand size has a greater impact on cost reduction than shipping size. The total logistics cost in the system is dependent on replenishment rate and flow rates from the higher to the lower echelon. High inventory cost is the result of a fast replenishment rate and frequent orders, while shipping cost is dependent on the flow rates in a process and total travelling time or total travelling distance. Shipping size also has an impact on the level of service and the total cost along with effective order variability.
文摘This paper analyzes the launch price of the launch vehicles, domestic and abroad, studies the status and trend of the low cost launch vehicles, and introduces two measures to reduce the cost by means of evolved and disruptive technologies, utilizing the concept of low cost manufacturing and operating modes as well. This paper also analyzes the launch strategies for small satellites such as piggyback, networking launch, and single launch with a small launch vehicle(SLV). Finally, the development trend of reusable launch vehicles is discussed as well as the development prospects for China's reusable launch vehicle.
文摘This paper considers a buyer＇s procuring strategy where the buyer purchases products from a supplier in order to minimize his total cost. Assume that the customer arrivals follow a Poisson process, a base-stock policy is implemented by the buyer, and the supplier will afford partial operating cost incurred by the buyer; The cost shared by the buyer includes procuring cost and some operating cost; The supplier does not hold the inventory and her production time is exponentially distributed. The objective of the supplier is to maximize her profit. The buyer designs a contract to minimize his total expected cost. Two different cases are considered： One potential supplier and many competing suppliers. The optimal control approaches are used to design the buyer＇s optimal mechanism and some simple procurement mechanisms are presented.
