In order to understand the interaction between large-scale vortex structure and particles, a two-way coupling temporal mixing layer laden with particles at a Stokes number of 5 with different mass loading planted init...In order to understand the interaction between large-scale vortex structure and particles, a two-way coupling temporal mixing layer laden with particles at a Stokes number of 5 with different mass loading planted initially in the upper half region is numerically studied. The pseudospectral method is used for the flow fluid and the Lagrangian approach is employed to trace particles. The momentum coupling effect introduced by a particle is approximated to a point force. The simulation results show that the coherent structures are still dominant in the mixing layer, but the large-scale vortex structure and particle dispersion are modulated. The length of large-scale vortex structure is shortened and the pairing is delayed. At the same time, the particles are distributed more evenly in the whole flow field as the mass loading is increased, but the particle dispersion along the transverse direction differs from that along the spanwise direction, which indicates that the effect by the addition of particle on the spanwise large-scale vortex structure is different from the streamwise counterpart.展开更多
Experiments were conducted to investigate the flow characteristics in the riser pipe and the suction pipe of airlift pump at a series of air flow rates and submergence ratios by using a high speed camcorder and a Lase...Experiments were conducted to investigate the flow characteristics in the riser pipe and the suction pipe of airlift pump at a series of air flow rates and submergence ratios by using a high speed camcorder and a Laser Doppler Velocimetvy system (LDV). A modified model was developed to predict the performance of airlift pump operating in gas-liquid two-phase flow, The results show that an unstable flow structure composed by a water falling film, a bubbly mixture, a water ascending film appearing alternately in riser pipe dominates the performance of airlift pump at large air flow rates. The bubbly mixture with a strongest capacity for pumping water first increases to its maximum and then slightly decreases. In suction pipe, the average velocity shows a flat profile and increases with increasing submergence ratio. Moreover, the predicted results of modified model are in good agreement with the experimental data in a margin of ± 12%.展开更多
Ecological economics and sustainable development economics are the basic theories to research on circulareconomy. Through the systemically research on the relationship of the three above, this paper thinks that the re...Ecological economics and sustainable development economics are the basic theories to research on circulareconomy. Through the systemically research on the relationship of the three above, this paper thinks that the reuse andrecycle of circular economy is a way that the stall is mended after a sheep is lost. Although the reduction technicallycontrols the production process, it cannot solve the waste caused by blind production and excess competition. We haveexperienced variety obstacles when implementing the circular economy, whose main reason is the conflict between theindividual ration and the social ration. Therefore, only when the individual ration and social ration incline to conformity,the cooperating Nash equilibrium will be appeared. In order to realize the harmony of ecology, economy and society, wehave to explore effective evaluation theory. This paper cites the "five flows of wealth operation theory" from professorMa Chuandong to search operation mechanism of circular economy, makes clear the developing thoughts of circulareconomy based on the realities, and brings forward some countermeasures to develop circular economy based on theabove theoretical analysis.展开更多
Taking B2C E-commerce enterprises as the center, it can be divided into a set of logistics activities upstream supply chain logistics producer to B2C e-commerce enterprises, and the B2C e-commerce enterprise logistics...Taking B2C E-commerce enterprises as the center, it can be divided into a set of logistics activities upstream supply chain logistics producer to B2C e-commerce enterprises, and the B2C e-commerce enterprise logistics to client consumer, and the paper focuses on the study of self-supporting logistics for the E-commerce enterprise. According to the development status of current B2C electronic commerce enterprise in our country and logistics, the paper study B2C electric business enterprise how to correctly choose the logistics mode and how to promote the business logistics operation level.展开更多
This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated pla...This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.展开更多
DAR (diffusion absorption refrigeration) cycle is driven by heat and has no moving parts. It is based on refrigerant and absorbent as the working fluid together with hydrogen as an auxiliary inert gas. To circulate ...DAR (diffusion absorption refrigeration) cycle is driven by heat and has no moving parts. It is based on refrigerant and absorbent as the working fluid together with hydrogen as an auxiliary inert gas. To circulate the working fluid without a mechanical pump, the diffusion absorption cycle relies on a bubble pump. Experimental system was designed and operated. Its aim was to investigate the performance of a bubble pump operating with three lifting tubes. The experimental results of the system were compared to existing models. The comparison showed that there was a bad agreement between the experimental and the theoretical results.展开更多
With the rapid development of China' s economy and the accelerating pace of economic globalization, the rapid expansion of trade appears in goods, materials; space to move also will expand in breadth and depth, and t...With the rapid development of China' s economy and the accelerating pace of economic globalization, the rapid expansion of trade appears in goods, materials; space to move also will expand in breadth and depth, and thus the efficiency of the logistics activities, rapid response capabilities and the level of information logistics put forward higher requirements. Meanwhile, the logistics needs of personalization, diversification and sophistication, require that logistics service companies must constantly improve and optimize enterprise business model, and target to develop new logistics services to adapt to changes in the logistics market, and improve the competitiveness of enterprises.Modem logistics enterprises refer to the concept of modem logistics as a guide, and the use of modem logistics and organization of modem logistics technology, it is to provide customers help and reduce logistics costs and improve the level of integrated logistics services to rationalize logistics enterprises. Modem logistics enterprises are in terms of philosophy, mode of operation, services, information technology degree, logistics technology, enterprise systems and others have higher requirements to react quickly, service serialization, standardization of operations, the target of systematic, modem means are the features of the organization which are different from the traditional network of logistics enterprises.展开更多
This paper evaluates the performances of the models that incorporate forecasting inflow for cascaded hydropower reservoirs operation. These models are constructed separately on the concepts of explicit stochastic opti...This paper evaluates the performances of the models that incorporate forecasting inflow for cascaded hydropower reservoirs operation. These models are constructed separately on the concepts of explicit stochastic optimization (ESO) and implicit sto- chastic optimization (ISO) as well as parametefization-simulation-optimization (PSO). Firstly, the aggregation-disaggregation method is implemented in ESO models to reduce the complexity of stochastic dynamic programming (SDP). And the aggre- gate flow SDP (AF-SDP) and aggregation-disaggregation SDP (AD-SDP) are constructed respectively. Secondly, in ISO mod- el, decision tree is the well-known and widespread algorithm. The algorithm C 5.0 is selected to extract the if-then-else rules for reservoir operation. Thirdly, based on the PSO model, the hedging rule curves (HRCs) are pre-defined by fusing the storage and inflow as state variable. The parameters of the HRCs are determined by using the simulation-optimization model. Finally, China's Hun River cascade hydropower reservoirs system is taken as an example to illustrate the efficiency and reliability of the models. In addition, the values of quantitative precipitation forecasts of the global forecast system (10 days lead-time) are implemented to forecast the 10 days inflow.展开更多
The hyporbeic zone plays an important role in groundwater and stream water quality protection. To investigate the stream-groundwater interaction mechanisms in the lateral hyporheic zone, this study examined Ma'an Cre...The hyporbeic zone plays an important role in groundwater and stream water quality protection. To investigate the stream-groundwater interaction mechanisms in the lateral hyporheic zone, this study examined Ma'an Creek in Chongqing during the dry season from December 2015 to April 2016. The water level, water temperature, pH and CF concentration in the hyporheic zone and groundwater were monitored in situ. The sediment permeability coefficient, stable isotopes of hydrogen and oxygen and concentration of DOC were analyzed. The results show that the water level changes of hyporheic zone and the movement of hyporheic flow were influenced significantly by the permeability coefficient of sediment. The hyporheic flow approximately 10 cm from the stream bank was clearly affected by precipitation infiltration and evapotranspiration. During the study period, the groundwater recharged the stream, and the impact of groundwater on the hyporheic flow gradually decreased with the flow path. The hyporheic flow approximately 30 cm from the stream bank was still mainly affected by groundwater. Approximately 10-30 cm from the stream bank, the mixing of groundwater with precipitation and stream water intensified. Due to the sediment properties, moisture accumulated approximately 10 cm from the stream bank and drained into the stream via hyporheic flow, with potential impacts on stream water quality.展开更多
基金Supported by the National Natural Science Foundation of China (No. 50236030, No. 50076038) and the Major State Basic Research Development Program of China (No. G19990222).
文摘In order to understand the interaction between large-scale vortex structure and particles, a two-way coupling temporal mixing layer laden with particles at a Stokes number of 5 with different mass loading planted initially in the upper half region is numerically studied. The pseudospectral method is used for the flow fluid and the Lagrangian approach is employed to trace particles. The momentum coupling effect introduced by a particle is approximated to a point force. The simulation results show that the coherent structures are still dominant in the mixing layer, but the large-scale vortex structure and particle dispersion are modulated. The length of large-scale vortex structure is shortened and the pairing is delayed. At the same time, the particles are distributed more evenly in the whole flow field as the mass loading is increased, but the particle dispersion along the transverse direction differs from that along the spanwise direction, which indicates that the effect by the addition of particle on the spanwise large-scale vortex structure is different from the streamwise counterpart.
基金Supported by the National Key Basic Research Development Program of China(2014CB239200)the National Natural Science Foundation of China(51474158)
文摘Experiments were conducted to investigate the flow characteristics in the riser pipe and the suction pipe of airlift pump at a series of air flow rates and submergence ratios by using a high speed camcorder and a Laser Doppler Velocimetvy system (LDV). A modified model was developed to predict the performance of airlift pump operating in gas-liquid two-phase flow, The results show that an unstable flow structure composed by a water falling film, a bubbly mixture, a water ascending film appearing alternately in riser pipe dominates the performance of airlift pump at large air flow rates. The bubbly mixture with a strongest capacity for pumping water first increases to its maximum and then slightly decreases. In suction pipe, the average velocity shows a flat profile and increases with increasing submergence ratio. Moreover, the predicted results of modified model are in good agreement with the experimental data in a margin of ± 12%.
文摘Ecological economics and sustainable development economics are the basic theories to research on circulareconomy. Through the systemically research on the relationship of the three above, this paper thinks that the reuse andrecycle of circular economy is a way that the stall is mended after a sheep is lost. Although the reduction technicallycontrols the production process, it cannot solve the waste caused by blind production and excess competition. We haveexperienced variety obstacles when implementing the circular economy, whose main reason is the conflict between theindividual ration and the social ration. Therefore, only when the individual ration and social ration incline to conformity,the cooperating Nash equilibrium will be appeared. In order to realize the harmony of ecology, economy and society, wehave to explore effective evaluation theory. This paper cites the "five flows of wealth operation theory" from professorMa Chuandong to search operation mechanism of circular economy, makes clear the developing thoughts of circulareconomy based on the realities, and brings forward some countermeasures to develop circular economy based on theabove theoretical analysis.
文摘Taking B2C E-commerce enterprises as the center, it can be divided into a set of logistics activities upstream supply chain logistics producer to B2C e-commerce enterprises, and the B2C e-commerce enterprise logistics to client consumer, and the paper focuses on the study of self-supporting logistics for the E-commerce enterprise. According to the development status of current B2C electronic commerce enterprise in our country and logistics, the paper study B2C electric business enterprise how to correctly choose the logistics mode and how to promote the business logistics operation level.
基金the National Science Foundation for Creative Re-search Groups of China (Grant No.50921001) for supporting this work
文摘This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.
文摘DAR (diffusion absorption refrigeration) cycle is driven by heat and has no moving parts. It is based on refrigerant and absorbent as the working fluid together with hydrogen as an auxiliary inert gas. To circulate the working fluid without a mechanical pump, the diffusion absorption cycle relies on a bubble pump. Experimental system was designed and operated. Its aim was to investigate the performance of a bubble pump operating with three lifting tubes. The experimental results of the system were compared to existing models. The comparison showed that there was a bad agreement between the experimental and the theoretical results.
文摘With the rapid development of China' s economy and the accelerating pace of economic globalization, the rapid expansion of trade appears in goods, materials; space to move also will expand in breadth and depth, and thus the efficiency of the logistics activities, rapid response capabilities and the level of information logistics put forward higher requirements. Meanwhile, the logistics needs of personalization, diversification and sophistication, require that logistics service companies must constantly improve and optimize enterprise business model, and target to develop new logistics services to adapt to changes in the logistics market, and improve the competitiveness of enterprises.Modem logistics enterprises refer to the concept of modem logistics as a guide, and the use of modem logistics and organization of modem logistics technology, it is to provide customers help and reduce logistics costs and improve the level of integrated logistics services to rationalize logistics enterprises. Modem logistics enterprises are in terms of philosophy, mode of operation, services, information technology degree, logistics technology, enterprise systems and others have higher requirements to react quickly, service serialization, standardization of operations, the target of systematic, modem means are the features of the organization which are different from the traditional network of logistics enterprises.
基金supported by the National Natural Science Foundation of China(Grant Nos.51379027,51109025)National Basic Research Program of China("973" project)(Grant No.2013CB036401)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.DUT13JS06)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20100041120004)the Hun River Cas-cade Hydropower Reservoirs Development Company,Ltd
文摘This paper evaluates the performances of the models that incorporate forecasting inflow for cascaded hydropower reservoirs operation. These models are constructed separately on the concepts of explicit stochastic optimization (ESO) and implicit sto- chastic optimization (ISO) as well as parametefization-simulation-optimization (PSO). Firstly, the aggregation-disaggregation method is implemented in ESO models to reduce the complexity of stochastic dynamic programming (SDP). And the aggre- gate flow SDP (AF-SDP) and aggregation-disaggregation SDP (AD-SDP) are constructed respectively. Secondly, in ISO mod- el, decision tree is the well-known and widespread algorithm. The algorithm C 5.0 is selected to extract the if-then-else rules for reservoir operation. Thirdly, based on the PSO model, the hedging rule curves (HRCs) are pre-defined by fusing the storage and inflow as state variable. The parameters of the HRCs are determined by using the simulation-optimization model. Finally, China's Hun River cascade hydropower reservoirs system is taken as an example to illustrate the efficiency and reliability of the models. In addition, the values of quantitative precipitation forecasts of the global forecast system (10 days lead-time) are implemented to forecast the 10 days inflow.
基金supported by the National Key Technology R&D Program of China(Grant No.2011BAC09B01)Fundamental Research Funds for the Central Universities(Grant Nos.XDJK2014A016&XDJK2016D046)Scientific and Technical Innovative Program of graduate students in Chongqing(Grant No.CYS16050)
文摘The hyporbeic zone plays an important role in groundwater and stream water quality protection. To investigate the stream-groundwater interaction mechanisms in the lateral hyporheic zone, this study examined Ma'an Creek in Chongqing during the dry season from December 2015 to April 2016. The water level, water temperature, pH and CF concentration in the hyporheic zone and groundwater were monitored in situ. The sediment permeability coefficient, stable isotopes of hydrogen and oxygen and concentration of DOC were analyzed. The results show that the water level changes of hyporheic zone and the movement of hyporheic flow were influenced significantly by the permeability coefficient of sediment. The hyporheic flow approximately 10 cm from the stream bank was clearly affected by precipitation infiltration and evapotranspiration. During the study period, the groundwater recharged the stream, and the impact of groundwater on the hyporheic flow gradually decreased with the flow path. The hyporheic flow approximately 30 cm from the stream bank was still mainly affected by groundwater. Approximately 10-30 cm from the stream bank, the mixing of groundwater with precipitation and stream water intensified. Due to the sediment properties, moisture accumulated approximately 10 cm from the stream bank and drained into the stream via hyporheic flow, with potential impacts on stream water quality.