This paper introduces an optimized planning approach for integrating photovoltaic as distributed generation (PV-DG) into the radial distribution power systems, utilizing exhaustive load flow (ELF), loss sensitivity fa...This paper introduces an optimized planning approach for integrating photovoltaic as distributed generation (PV-DG) into the radial distribution power systems, utilizing exhaustive load flow (ELF), loss sensitivity factor (LSF), genetic algorithms (GA) methods, and numerical method based on LSF. The methodology aims to determine the optimal allocation and sizing of multiple PV-DG to minimize power loss through time series power flow analysis. An approach utilizing continuous sensitivity analysis is developed and inherently leverages power flow and loss equations to compute LSF of all buses in the system towards employing a dynamic PV-DG model for more accurate results. The algorithm uses a numerical grid search method to optimize PV-DG placement in a power distribution system, focusing on minimizing system losses. It combines iterative analysis, sensitivity assessment, and comprehensive visualization to identify and present the optimal PV-DG configurations. The present-ed algorithms are verified through co-simulation framework combining MATLAB and OpenDSS to carry out analysis for 12-bus radial distribution test system. The proposed numerical method is compared with other algorithms, such as ELF, LSF methods, and Genetic Algorithms (GA). Results show that the proposed numerical method performs well in comparison with LSF and ELF solutions.展开更多
The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic...The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic applications. However, such conventional DEP-based device is relatively complicated and difficult for fabrication. A concise microfluidic device is presented for effective continuous separation of multiple size particle mixtures. A pair of acupuncture needle electrodes are creatively employed and embedded in a PDMS（poly-dimethylsiloxane） hurdle for generating non-uniform electric field thereby achieving a continuous DEP separation. The separation mechanism is that the incoming particle samples with different sizes experience different negative DEP（n DEP） forces and then they can be transported into different downstream outlets. The DEP characterizations of particles are calculated, and their trajectories are numerically predicted by considering the combined action of the incoming laminar flow and the n DEP force field for guiding the separation experiments. The device performance is verified by successfully separating a three-sized particle mixture, including polystyrene microspheres with diameters of 3 μm, 10 μm and 25 μm. The separation purity is below 70% when the flow rate ratio is less than 3.5 or more than 5.1, while the separation purity can be up to more than 90% when the flow rate ratio is between 3.5 and 5.1 and meanwhile ensure the voltage output falls in between 120 V and 150 V. Such simple DEP-based separation device has extensive applications in future microfluidic systems.展开更多
Airlift reactors are used in a wide range of industries,such as hydrometallurgy,biochemical processes,chemical process industry and wastewater treatment.Despite the simple structure of airlift reactors,the flow field ...Airlift reactors are used in a wide range of industries,such as hydrometallurgy,biochemical processes,chemical process industry and wastewater treatment.Despite the simple structure of airlift reactors,the flow field becomes complex with increasing gas velocity,and gas bubbles in the circulating regime can be observed in practice.In this paper,a numerical modelling method based on computational fluid dynamics(CFD)is presented for gas-liquid flow in airlift reactors under different bubble recirculation regimes.Gas-liquid flow was modelled using the Eulerian two-fluid equations,and extra user defined subroutines were incorporated to consider the complex physics,such as bubble-induced turbulence and turbulent dispersion force.Some alternative correlations for drag coefficient were tested to compare their ability to capture the bubble distributions in the riser and downcomer of the airlift reactors,with consideration of the interaction between bubbles.A model including multiple bubble sizes was applied to obtain more accurate simulation results of gas holdup and water velocity.Also,the use of the inhomogeneous multiple-size-group(MUSIG)model was explored as a way to better predict the complex flow regimes.The modelling method was applied to a laboratory internal loop airlift reactor,and the simulation results were compared with the published experimental measurements for gas holdup and water velocity.Reasonable agreement was obtained over a range of operating conditions,and an improvement was demonstrated using the proposed method.The simulations have shown that the inhomogeneous MUSIG model is a suitable tool to describe the complex gas-liquid interaction in the airlift reactor at a high gas superficial velocity.展开更多
Page migration has long been adopted in hybrid memory systems comprising dynamic random access memory(DRAM)and non-volatile memories(NVMs),to improve the system performance and energy efficiency.However,page migration...Page migration has long been adopted in hybrid memory systems comprising dynamic random access memory(DRAM)and non-volatile memories(NVMs),to improve the system performance and energy efficiency.However,page migration introduces some side effects,such as more translation lookaside buffer(TLB)misses,breaking memory contiguity,and extra memory accesses due to page table updating.In this paper,we propose superpagefriendly page table called SuperPT to reduce the performance overhead of serving TLB misses.By leveraging a virtual hashed page table and a hybrid DRAM allocator,SuperPT performs address translations in a flexible and efficient way while still remaining the contiguity within the migrated pages.展开更多
文摘This paper introduces an optimized planning approach for integrating photovoltaic as distributed generation (PV-DG) into the radial distribution power systems, utilizing exhaustive load flow (ELF), loss sensitivity factor (LSF), genetic algorithms (GA) methods, and numerical method based on LSF. The methodology aims to determine the optimal allocation and sizing of multiple PV-DG to minimize power loss through time series power flow analysis. An approach utilizing continuous sensitivity analysis is developed and inherently leverages power flow and loss equations to compute LSF of all buses in the system towards employing a dynamic PV-DG model for more accurate results. The algorithm uses a numerical grid search method to optimize PV-DG placement in a power distribution system, focusing on minimizing system losses. It combines iterative analysis, sensitivity assessment, and comprehensive visualization to identify and present the optimal PV-DG configurations. The present-ed algorithms are verified through co-simulation framework combining MATLAB and OpenDSS to carry out analysis for 12-bus radial distribution test system. The proposed numerical method is compared with other algorithms, such as ELF, LSF methods, and Genetic Algorithms (GA). Results show that the proposed numerical method performs well in comparison with LSF and ELF solutions.
基金Supported by National Natural Science Foundation of China(Grant No.51305106)Fundamental Research Funds for the Central Universities,China(Grant Nos.HIT.NSRIF.2014058,HIT.IBRSEM.201319)Open Foundation of State Key Laboratory of Fluid Power Transmission and Control,China(GZKF-201402)
文摘The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic applications. However, such conventional DEP-based device is relatively complicated and difficult for fabrication. A concise microfluidic device is presented for effective continuous separation of multiple size particle mixtures. A pair of acupuncture needle electrodes are creatively employed and embedded in a PDMS（poly-dimethylsiloxane） hurdle for generating non-uniform electric field thereby achieving a continuous DEP separation. The separation mechanism is that the incoming particle samples with different sizes experience different negative DEP（n DEP） forces and then they can be transported into different downstream outlets. The DEP characterizations of particles are calculated, and their trajectories are numerically predicted by considering the combined action of the incoming laminar flow and the n DEP force field for guiding the separation experiments. The device performance is verified by successfully separating a three-sized particle mixture, including polystyrene microspheres with diameters of 3 μm, 10 μm and 25 μm. The separation purity is below 70% when the flow rate ratio is less than 3.5 or more than 5.1, while the separation purity can be up to more than 90% when the flow rate ratio is between 3.5 and 5.1 and meanwhile ensure the voltage output falls in between 120 V and 150 V. Such simple DEP-based separation device has extensive applications in future microfluidic systems.
基金support from National Key R&D Program of China(No.2021YFC2902700)pilot project of BGRIMM Technology Group(No.02-2407)special fund of National Key Laboratory of Ni&Co Associated Minerals Resources Development and Comprehensive Utilization(No.GZSYS-KY-2022-014).
文摘Airlift reactors are used in a wide range of industries,such as hydrometallurgy,biochemical processes,chemical process industry and wastewater treatment.Despite the simple structure of airlift reactors,the flow field becomes complex with increasing gas velocity,and gas bubbles in the circulating regime can be observed in practice.In this paper,a numerical modelling method based on computational fluid dynamics(CFD)is presented for gas-liquid flow in airlift reactors under different bubble recirculation regimes.Gas-liquid flow was modelled using the Eulerian two-fluid equations,and extra user defined subroutines were incorporated to consider the complex physics,such as bubble-induced turbulence and turbulent dispersion force.Some alternative correlations for drag coefficient were tested to compare their ability to capture the bubble distributions in the riser and downcomer of the airlift reactors,with consideration of the interaction between bubbles.A model including multiple bubble sizes was applied to obtain more accurate simulation results of gas holdup and water velocity.Also,the use of the inhomogeneous multiple-size-group(MUSIG)model was explored as a way to better predict the complex flow regimes.The modelling method was applied to a laboratory internal loop airlift reactor,and the simulation results were compared with the published experimental measurements for gas holdup and water velocity.Reasonable agreement was obtained over a range of operating conditions,and an improvement was demonstrated using the proposed method.The simulations have shown that the inhomogeneous MUSIG model is a suitable tool to describe the complex gas-liquid interaction in the airlift reactor at a high gas superficial velocity.
文摘Page migration has long been adopted in hybrid memory systems comprising dynamic random access memory(DRAM)and non-volatile memories(NVMs),to improve the system performance and energy efficiency.However,page migration introduces some side effects,such as more translation lookaside buffer(TLB)misses,breaking memory contiguity,and extra memory accesses due to page table updating.In this paper,we propose superpagefriendly page table called SuperPT to reduce the performance overhead of serving TLB misses.By leveraging a virtual hashed page table and a hybrid DRAM allocator,SuperPT performs address translations in a flexible and efficient way while still remaining the contiguity within the migrated pages.
