In the environment of customization, disturbances such as rush orders and material shortages often occur in the manufacturing system, so rescheduling is necessary for the manufacturing system. The rescheduling methodo...In the environment of customization, disturbances such as rush orders and material shortages often occur in the manufacturing system, so rescheduling is necessary for the manufacturing system. The rescheduling methodology should be able to dispose of the disturbance efficiently so as to keep production going smoothly. This aims researching flow shop rescheduling problem (FSRP) necessitated by rush orders. Disjunctive graph is employed to demonstrate the FSRP. For a flow shop processing n jobs, after the original schedule has been made, and z out of n jobs have been processed in the flow shop, x rush orders come, so the original n jobs together with x rush orders should be rescheduled immediately so that the rush orders would be processed in the shortest time and the original jobs could be processed subject to some optimized criteria. The weighted mean flow time of both original jobs and rush orders is used as objective function. The weight for rush orders is much bigger than that of the original jobs, so the rush orders should be processed early in the new schedule. The ant colony optimization (ACO) algorithm used to solve the rescheduling problem has a weakness in that the search may fall into a local optimum. Mutation operation is employed to enhance the ACO performance. Numerical experiments demonstrated that the proposed algorithm has high computation repeatability and efficiency.展开更多
The purification and separation of durene from the mixture containing durene isomers were studied.Since the boiling points of tetramethyl benzene isomers are very close but their melting points are of great difference...The purification and separation of durene from the mixture containing durene isomers were studied.Since the boiling points of tetramethyl benzene isomers are very close but their melting points are of great differences,static melt crystallization was applied to separate and purify durene from its isomers.Crystallization experiments were carried out under various operating conditions.The effects of cooling rate,crystallization temperature,sweating temperature and sweating time on the yield and purity of crystal were investigated.Orthogonal experimental design method was adopted to analyze the factors that may affect the yield of durene.Under the optimal crystallization conditions,the purity of durene could reach as high as 99.06%with the yield of 75.3%through one crystallization process.By fitting purification data based on sweating time in isothermal operations,the purification rate coefficient was obtained.展开更多
Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scal...Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scale to large underground structures. Stimulation can occur from unwanted electromagnetic signals entering the buried system, and for assessing the operating state of a buried system that is not usually physically accessible. In both cases detecting damage or status can be accomplished by examining the time dependence of the resultant surface temperature. This study shows how to determine surface temperature for a hypothetical thermal-plus-systems using a combination of Fourier-space and Laplace-time transform techniques. The hypothetical model can be generalized from scaling the relevant relationships.展开更多
The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order t...The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order to predict the behaviors of the adsorption chiller system and find the influence of working conditions on its operation. For the working process of the main components of the system, including adsorber, condenser and evaporator, the coupled unsteady equations were set up for each stage. The model was then solved using stable numerical methods from EES （equation engineering solver）, and the performance of the adsorber and condenser/evaporator of the system was analyzed. The condensation, evaporation and adsorber temperature values as well as the adsorption ratio and desorption ratio were obtained as function of operating time. Also, the coefficient of performance was analyzed in function of the heat source temperature and the cooling source temperature.展开更多
文摘In the environment of customization, disturbances such as rush orders and material shortages often occur in the manufacturing system, so rescheduling is necessary for the manufacturing system. The rescheduling methodology should be able to dispose of the disturbance efficiently so as to keep production going smoothly. This aims researching flow shop rescheduling problem (FSRP) necessitated by rush orders. Disjunctive graph is employed to demonstrate the FSRP. For a flow shop processing n jobs, after the original schedule has been made, and z out of n jobs have been processed in the flow shop, x rush orders come, so the original n jobs together with x rush orders should be rescheduled immediately so that the rush orders would be processed in the shortest time and the original jobs could be processed subject to some optimized criteria. The weighted mean flow time of both original jobs and rush orders is used as objective function. The weight for rush orders is much bigger than that of the original jobs, so the rush orders should be processed early in the new schedule. The ant colony optimization (ACO) algorithm used to solve the rescheduling problem has a weakness in that the search may fall into a local optimum. Mutation operation is employed to enhance the ACO performance. Numerical experiments demonstrated that the proposed algorithm has high computation repeatability and efficiency.
基金Supported by the National Natural Science Foundation of China(21176172)Top Talents Program of Yunnan Province,China(2011HA010)
文摘The purification and separation of durene from the mixture containing durene isomers were studied.Since the boiling points of tetramethyl benzene isomers are very close but their melting points are of great differences,static melt crystallization was applied to separate and purify durene from its isomers.Crystallization experiments were carried out under various operating conditions.The effects of cooling rate,crystallization temperature,sweating temperature and sweating time on the yield and purity of crystal were investigated.Orthogonal experimental design method was adopted to analyze the factors that may affect the yield of durene.Under the optimal crystallization conditions,the purity of durene could reach as high as 99.06%with the yield of 75.3%through one crystallization process.By fitting purification data based on sweating time in isothermal operations,the purification rate coefficient was obtained.
文摘Mathematical investigations of the dynamic response of buried systems to thermal and/or electromagnetic stimulation continues to be of great importance. The size of such systems can range from the microelectronic scale to large underground structures. Stimulation can occur from unwanted electromagnetic signals entering the buried system, and for assessing the operating state of a buried system that is not usually physically accessible. In both cases detecting damage or status can be accomplished by examining the time dependence of the resultant surface temperature. This study shows how to determine surface temperature for a hypothetical thermal-plus-systems using a combination of Fourier-space and Laplace-time transform techniques. The hypothetical model can be generalized from scaling the relevant relationships.
文摘The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order to predict the behaviors of the adsorption chiller system and find the influence of working conditions on its operation. For the working process of the main components of the system, including adsorber, condenser and evaporator, the coupled unsteady equations were set up for each stage. The model was then solved using stable numerical methods from EES （equation engineering solver）, and the performance of the adsorber and condenser/evaporator of the system was analyzed. The condensation, evaporation and adsorber temperature values as well as the adsorption ratio and desorption ratio were obtained as function of operating time. Also, the coefficient of performance was analyzed in function of the heat source temperature and the cooling source temperature.
