The existing research of the flow behavior in emitter micro-channels mainly focuses on the single-phase flow behavior.And the recent micro-particle image velocimetry（PIV） experimental research on the flow characteri...The existing research of the flow behavior in emitter micro-channels mainly focuses on the single-phase flow behavior.And the recent micro-particle image velocimetry（PIV） experimental research on the flow characteristics in various micro-channels mainly focuses on the single-phase fluid flow.However,using an original-size emitter prototype to perform the experiments on the two-phase flow characteristics of the labyrinth channels is seldom reported.In this paper,the practical flow of water,mixed with sand escaped from filtering,in the labyrinth channel,is investigated.And some research work on the clogging mechanism of the labyrinth channel＇s structure is conducted.Computational fluid dynamics（CFD） analysis has been performed on liquid-solid two-phase flow in labyrinth-channel emitters.Based on flow visualization technology-micro-PIV,the flow in labyrinth channel has been photographed and recorded.The path line graph and velocity vector graph are obtained through the post-treatment of experimental results.The graphs agree well with CFD analysis results,so CFD analysis can be used in optimal design of labyrinth-channel emitters.And the optimized anti-clogging structures of the rectangular channel and zigzag channel have been designed here.The CFD numerical simulation and the micro-PIV experiments analysis on labyrinth-channel emitter,make the ＂black box＂ of the flow behavior in the emitter channel broken.Furthermore,the proposed research promotes an advanced method to evaluate the emitter＇s performance and can be used to conducting the optimal design of the labyrinth-channel emitters.展开更多
Xi'an Jiaotong University (XJTU)has carded out the research of additive manufacturing (AM)since 1993,who is one of the earliest institutes majoring in AM.After 20years of effort,XJTU has made great progress on the...Xi'an Jiaotong University (XJTU)has carded out the research of additive manufacturing (AM)since 1993,who is one of the earliest institutes majoring in AM.After 20years of effort,XJTU has made great progress on the additive manufacturing of polymer,metals,ceramics,composite materials and intelligent materials.XJTU has established a research team that features the engineering application of rapid manufacturing system.展开更多
Aiming at the part quality and building time problems in stereolithography （SL） caused by unreasonable building orientation, a part building orientation decision method in SL rapid prototyping （RP） is carried out....Aiming at the part quality and building time problems in stereolithography （SL） caused by unreasonable building orientation, a part building orientation decision method in SL rapid prototyping （RP） is carried out. Bringing into full consideration of the deformation, stair-stepping effect, overcure effect and building time related to the part fabrication orientation, and using evaluation function method, a multi-objective optimization model for the building orientation is defined. According to the difference in the angles between normal vectors of triangular facets in standard triangulation language （STL） model and z axis, the expressions of deformation area, stair-stepping area, overcure area are established. According to the characteristics in SL process, part building time is divided into four sections, that is, hatching scanning time, outline scanning time, support building time and layer waiting time. Expressions of each building time section are given. Considering the features of this optimization model, genetic algorithm （GA） is used to derive the optimization objective, related software is developed and optimization results are tested through experiments. Application shows that this method can effectively solve the quality and efficiency troubles caused by unreasonable part building orientation, an automatic orientation-determining program is developed and verified through test.展开更多
For reducing traffic jams without widening streets,we come up with a tenement rearrangement problem.In this paper,we study a tenement allocation model which includes two types of tenants,i.e.,typical tenants and speci...For reducing traffic jams without widening streets,we come up with a tenement rearrangement problem.In this paper,we study a tenement allocation model which includes two types of tenants,i.e.,typical tenants and special tenants who owned houses by themselves.The optimal allocation is that total transportation cost is minimized without undermining tenants’individual housing preference or increasing individual cost.Besides,we present a Modified Hungarian Algorithm for the above tenement allocation problem and prove that it can be solved in polynomial time.Furthermore,computational tests show that this algorithm has a good performance.展开更多
基金supported by National Natural Science Foundation of China (Grant Nos. 50675172,50975227)Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No.FANEDD200740)National Hi-tech Research and Development of China (863 Program,Grant No. 2011AA100507-04)
文摘The existing research of the flow behavior in emitter micro-channels mainly focuses on the single-phase flow behavior.And the recent micro-particle image velocimetry（PIV） experimental research on the flow characteristics in various micro-channels mainly focuses on the single-phase fluid flow.However,using an original-size emitter prototype to perform the experiments on the two-phase flow characteristics of the labyrinth channels is seldom reported.In this paper,the practical flow of water,mixed with sand escaped from filtering,in the labyrinth channel,is investigated.And some research work on the clogging mechanism of the labyrinth channel＇s structure is conducted.Computational fluid dynamics（CFD） analysis has been performed on liquid-solid two-phase flow in labyrinth-channel emitters.Based on flow visualization technology-micro-PIV,the flow in labyrinth channel has been photographed and recorded.The path line graph and velocity vector graph are obtained through the post-treatment of experimental results.The graphs agree well with CFD analysis results,so CFD analysis can be used in optimal design of labyrinth-channel emitters.And the optimized anti-clogging structures of the rectangular channel and zigzag channel have been designed here.The CFD numerical simulation and the micro-PIV experiments analysis on labyrinth-channel emitter,make the ＂black box＂ of the flow behavior in the emitter channel broken.Furthermore,the proposed research promotes an advanced method to evaluate the emitter＇s performance and can be used to conducting the optimal design of the labyrinth-channel emitters.
文摘Xi'an Jiaotong University (XJTU)has carded out the research of additive manufacturing (AM)since 1993,who is one of the earliest institutes majoring in AM.After 20years of effort,XJTU has made great progress on the additive manufacturing of polymer,metals,ceramics,composite materials and intelligent materials.XJTU has established a research team that features the engineering application of rapid manufacturing system.
基金This project is supported by National Hi-tech Research and Development Program of China(863 Program, No.2005AA414020).
文摘Aiming at the part quality and building time problems in stereolithography （SL） caused by unreasonable building orientation, a part building orientation decision method in SL rapid prototyping （RP） is carried out. Bringing into full consideration of the deformation, stair-stepping effect, overcure effect and building time related to the part fabrication orientation, and using evaluation function method, a multi-objective optimization model for the building orientation is defined. According to the difference in the angles between normal vectors of triangular facets in standard triangulation language （STL） model and z axis, the expressions of deformation area, stair-stepping area, overcure area are established. According to the characteristics in SL process, part building time is divided into four sections, that is, hatching scanning time, outline scanning time, support building time and layer waiting time. Expressions of each building time section are given. Considering the features of this optimization model, genetic algorithm （GA） is used to derive the optimization objective, related software is developed and optimization results are tested through experiments. Application shows that this method can effectively solve the quality and efficiency troubles caused by unreasonable part building orientation, an automatic orientation-determining program is developed and verified through test.
基金the National Natural Science Foundation of China(No.61221063)a Special Financial Grant from the China Postdoctoral Science Foundation(No.2015T81040).
文摘For reducing traffic jams without widening streets,we come up with a tenement rearrangement problem.In this paper,we study a tenement allocation model which includes two types of tenants,i.e.,typical tenants and special tenants who owned houses by themselves.The optimal allocation is that total transportation cost is minimized without undermining tenants’individual housing preference or increasing individual cost.Besides,we present a Modified Hungarian Algorithm for the above tenement allocation problem and prove that it can be solved in polynomial time.Furthermore,computational tests show that this algorithm has a good performance.
