Nitrogen is one of the most important elements that can limit plant growth in forest ecosystems. Studies of nitrogen mineralization, nitrogen saturation and nitrogen cycle in forest ecosystems is very necessary for un...Nitrogen is one of the most important elements that can limit plant growth in forest ecosystems. Studies of nitrogen mineralization, nitrogen saturation and nitrogen cycle in forest ecosystems is very necessary for understanding the productivity of stand, nutrient cycle and turnover of nitrogen of forest ecosystems. Based on comparison and analysis of domestic and in-ternational academic references related to studies on nitrogen mineralization, nitrogen saturation and nitrogen cycle in recent 10 years, the current situation and development of the study on these aspects, and the problems existed in current researches were reviewed. At last, some advices were given for future researches.展开更多
This paper focuses on the mixed-refrigerant refrigeration process flows which are applied in the cryogenic separation section of ethylene plant. Based on a 120 kt/a ethylene plant which employs a sequence separation p...This paper focuses on the mixed-refrigerant refrigeration process flows which are applied in the cryogenic separation section of ethylene plant. Based on a 120 kt/a ethylene plant which employs a sequence separation process flow and lowpressure demethanization system, the energy consumption of three refrigeration process flows（typical cascade refrigeration, binary refrigeration and tertiary refrigeration） was calculated by means of the ASPEN PLUS simulation software. An optimized mixed-refrigerant composition which achieved the minimum energy consumption of refrigeration systems was found out and the exergy loss was analyzed and compared. Results indicated that the energy consumption of typical cascade refrigeration and binary refrigeration systems was almost equal and that of tertiary refrigeration system was higher than the other two systems. Based on the current situation of production, the suggestions on production optimization and refrigeration process flow selection were put forward.展开更多
An increase in public environmental awareness and pressures from the government’s determination to deal with environmental problems force manufacturers to implement green manufacturing(GM).However,since managers and ...An increase in public environmental awareness and pressures from the government’s determination to deal with environmental problems force manufacturers to implement green manufacturing(GM).However,since managers and stakeholders lack understanding of GM and its complexity,the manufacturing enterprise,especially the small and medium ones,are constantly facing the problems of how to make a reasonable decision for an environmental problem,and the adopted approaches have no clear payoffs.The customized design,flexible production,and diversified services in customized production make the problems more challenging.In order to solve this problem,this paper proposes a framework for the implementation of GM in customized products manufacturing enterprises(CPME).A three-layer framework,i.e.,the goal layer,the product life-cycle layer and the supporting layer,is designed to provide a methodology to help implement GM.In this model,the GM practice processes are divided into four stages from the life-cycle perspective,i.e.design,production,use,and disposal.The preliminary practice of GM in an electrical product manufacturing company is carried out,and the implementation effect shows that the system framework is helpful to make a comprehensive understanding of GM and to improve the operability of GM practices.The integrated product model is an effective way to integrate the life cycle data.展开更多
Various nodes,logistics,capital flows,and information flows are required to make systematic decisions concerning the operation of an integrated coal supply system. We describe a quantitative analysis of such a system....Various nodes,logistics,capital flows,and information flows are required to make systematic decisions concerning the operation of an integrated coal supply system. We describe a quantitative analysis of such a system. A dynamic optimization model of the supply chain is developed. It has achieved optimal system profit under conditions guaranteeing a certain level of customer satisfaction. Applying this model to coal production of the Xuzhou coal mines allows recommendations for a more systematic use of washing and processing,transportation and sale resources for commercial coal production to be made. The results show that this model,which is scientific and effective,has an important value for making reasonable decisions related to complex coal enterprises.展开更多
基金Forest Ecosystem Research of Liangshui & Maorshan Station of Heilongjiang Province (CFERN, No. 2001-02).
文摘Nitrogen is one of the most important elements that can limit plant growth in forest ecosystems. Studies of nitrogen mineralization, nitrogen saturation and nitrogen cycle in forest ecosystems is very necessary for understanding the productivity of stand, nutrient cycle and turnover of nitrogen of forest ecosystems. Based on comparison and analysis of domestic and in-ternational academic references related to studies on nitrogen mineralization, nitrogen saturation and nitrogen cycle in recent 10 years, the current situation and development of the study on these aspects, and the problems existed in current researches were reviewed. At last, some advices were given for future researches.
文摘This paper focuses on the mixed-refrigerant refrigeration process flows which are applied in the cryogenic separation section of ethylene plant. Based on a 120 kt/a ethylene plant which employs a sequence separation process flow and lowpressure demethanization system, the energy consumption of three refrigeration process flows（typical cascade refrigeration, binary refrigeration and tertiary refrigeration） was calculated by means of the ASPEN PLUS simulation software. An optimized mixed-refrigerant composition which achieved the minimum energy consumption of refrigeration systems was found out and the exergy loss was analyzed and compared. Results indicated that the energy consumption of typical cascade refrigeration and binary refrigeration systems was almost equal and that of tertiary refrigeration system was higher than the other two systems. Based on the current situation of production, the suggestions on production optimization and refrigeration process flow selection were put forward.
基金supported by the National Key R&D Program of China(No.2018YFB2002102)。
文摘An increase in public environmental awareness and pressures from the government’s determination to deal with environmental problems force manufacturers to implement green manufacturing(GM).However,since managers and stakeholders lack understanding of GM and its complexity,the manufacturing enterprise,especially the small and medium ones,are constantly facing the problems of how to make a reasonable decision for an environmental problem,and the adopted approaches have no clear payoffs.The customized design,flexible production,and diversified services in customized production make the problems more challenging.In order to solve this problem,this paper proposes a framework for the implementation of GM in customized products manufacturing enterprises(CPME).A three-layer framework,i.e.,the goal layer,the product life-cycle layer and the supporting layer,is designed to provide a methodology to help implement GM.In this model,the GM practice processes are divided into four stages from the life-cycle perspective,i.e.design,production,use,and disposal.The preliminary practice of GM in an electrical product manufacturing company is carried out,and the implementation effect shows that the system framework is helpful to make a comprehensive understanding of GM and to improve the operability of GM practices.The integrated product model is an effective way to integrate the life cycle data.
文摘Various nodes,logistics,capital flows,and information flows are required to make systematic decisions concerning the operation of an integrated coal supply system. We describe a quantitative analysis of such a system. A dynamic optimization model of the supply chain is developed. It has achieved optimal system profit under conditions guaranteeing a certain level of customer satisfaction. Applying this model to coal production of the Xuzhou coal mines allows recommendations for a more systematic use of washing and processing,transportation and sale resources for commercial coal production to be made. The results show that this model,which is scientific and effective,has an important value for making reasonable decisions related to complex coal enterprises.
