In view of the poor water supply system’s network properties, the system’s complicated network hydraulic equations were replaced by macroscopic nodal pressure model and the model of relationship between supply flow ...In view of the poor water supply system’s network properties, the system’s complicated network hydraulic equations were replaced by macroscopic nodal pressure model and the model of relationship between supply flow and water source head. By using pump-station pressure head and initial tank water levels as decision variables, the model of optimal allocation of water supply between pump-sources was developed. Genetic algorithm was introduced to deal with the model of optimal allocation of water supply. Methods for handling each constraint condition were put forward, and overcome the shortcoming such as premature convergence of genetic algorithm; a solving method was brought forward in which genetic algorithm was combined with simulated annealing technology and self-adaptive crossover and mutation probabilities were adopted. An application example showed the feasibility of this algorithm.展开更多
The stochastic production function estimates of rice and maize in Senegal River Valley demonstrate the possibility to reach self-sufficiency of rice in Senegal. Nonetheless, its fulfillment requires many accompanying ...The stochastic production function estimates of rice and maize in Senegal River Valley demonstrate the possibility to reach self-sufficiency of rice in Senegal. Nonetheless, its fulfillment requires many accompanying measures in rice and maize production. These measures include all upstream and downstream activities related to agricultural production for their efficiency and sustainability in rice and maize production to maintain the country＇s comparative advantages and competitiveness. Then priorities should be given to agricultural infrastructure building, establishment of credit markets, and providing an easy access of production factors （e.g., improved land, fertilizers, improved and certified seeds, as well as agricultural machines）. Furthermore, policy makers should provide a larger incentive in terms of producer price to encourage farmers to increase considerably their outputs, thereby farmers face smaller risk of having non-sold outputs. And during an early harvesting period, appropriate policy measures are in need to prevent farmers from dumping their products under severe social and economic pressures such as children schooling and loan payment, etc展开更多
It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a ...It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.展开更多
基金Project (No. 50078048) supported by the National Natural Science Foundation of China
文摘In view of the poor water supply system’s network properties, the system’s complicated network hydraulic equations were replaced by macroscopic nodal pressure model and the model of relationship between supply flow and water source head. By using pump-station pressure head and initial tank water levels as decision variables, the model of optimal allocation of water supply between pump-sources was developed. Genetic algorithm was introduced to deal with the model of optimal allocation of water supply. Methods for handling each constraint condition were put forward, and overcome the shortcoming such as premature convergence of genetic algorithm; a solving method was brought forward in which genetic algorithm was combined with simulated annealing technology and self-adaptive crossover and mutation probabilities were adopted. An application example showed the feasibility of this algorithm.
文摘The stochastic production function estimates of rice and maize in Senegal River Valley demonstrate the possibility to reach self-sufficiency of rice in Senegal. Nonetheless, its fulfillment requires many accompanying measures in rice and maize production. These measures include all upstream and downstream activities related to agricultural production for their efficiency and sustainability in rice and maize production to maintain the country＇s comparative advantages and competitiveness. Then priorities should be given to agricultural infrastructure building, establishment of credit markets, and providing an easy access of production factors （e.g., improved land, fertilizers, improved and certified seeds, as well as agricultural machines）. Furthermore, policy makers should provide a larger incentive in terms of producer price to encourage farmers to increase considerably their outputs, thereby farmers face smaller risk of having non-sold outputs. And during an early harvesting period, appropriate policy measures are in need to prevent farmers from dumping their products under severe social and economic pressures such as children schooling and loan payment, etc
文摘It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.
