Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in th...Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in the longer term. Renewable energy generation technologies including onshore wind, offshore wind, wave,tidal, marine current, and ocean thermal energy generation as well as PV power generation, which are considered展开更多
Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbin...Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,camera calibration,distortion correction,the semi-automatic high-precision extraction of targets,coordinate systems unification,and bundle adjustment,etc. The relatively convenient construction method of the measuring system can provide an abundant measuring content,a wide measuring range and post processing.The experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement higher than 0.1mm.展开更多
At the background of urban and rural integration,this paper analyzed and discussed factors restricting large-scale farmland operation in China's hilly areas from the qualitative perspective. It recognized large-sc...At the background of urban and rural integration,this paper analyzed and discussed factors restricting large-scale farmland operation in China's hilly areas from the qualitative perspective. It recognized large-scale farmland operation on the basis of the long tail theory. Finally,it came up with recommendations for developing large-scale farmland operation in hilly areas.展开更多
Bunsen burner is a typical geometry for investigating the turbulence-flame interaction.In most experimental studies,only turbulence intensity u′and integral scale l0 are used to characterize the turbulent flow field,...Bunsen burner is a typical geometry for investigating the turbulence-flame interaction.In most experimental studies,only turbulence intensity u′and integral scale l0 are used to characterize the turbulent flow field,regardless of the perforation geometry of perforated plates.However,since the geometry influences the developing process and vortex broken,the plate geometry has to be considered when discussing the flame-turbulence interaction.In order to investigate conditions at the same l0 and u′using different geometries,large eddy simulation of CH_(4)/air flames with dynamic TF combustion model was performed.The model validation shows good agreement between Large Eddy Simulation(LES)and experimental results.In the non-reacting flows,the Vortex Stretching of circular-perforated plate condition is always larger than that of slot-perforated plate condition,which comes from the stresses in the flow fields to stretch the vorticity vector.In reacting flows,at the root of the flame,the Vortex Stretching plays a major role,and the total vorticity here of circular-perforated plate condition is still larger(53.8%and 300%larger than that of the slot-perforated plate at x/D=0 and x/D=2.5,respectively).More small-scale vortex in circular-perforated plate condition can affect and wrinkle the flame front to increase the Probability Density Function(PDF)at large curvatures.The 3D curvature distributions of both cases bias to negative values.The negative trend of curvatures at the instant flame front results from the Dilatation term.Also,the value of the Vortex Stretching and the Dilatation at the flame front of circular-perforated plate condition is obviously larger.展开更多
The increasing penetration of wind power brings great uncertainties into power systems,which poses challenges to system planning and operation.This paper proposes a novel probabilistic load flow(PLF)method based on cl...The increasing penetration of wind power brings great uncertainties into power systems,which poses challenges to system planning and operation.This paper proposes a novel probabilistic load flow(PLF)method based on clustering technique to handle large fluctuations from large-scale wind power integration.The traditional cumulant method(CM)for PLF is based on the linearization of load flow equations around the operation point,therefore resulting in significant errors when input random variables have large fluctuations.In the proposed method,the samples of wind power and loads are first generated by the inverse Nataf transformation and then clustered using an improved K-means algorithm to obtain input variable samples with small variances in each cluster.With such pre-processing,the cumulant method can be applied within each cluster to calculate cumulants of output random variables with improved accuracy.The results obtained in each cluster are combined according to the law of total probability to calculate the final cumulants of output random variables for the whole samples.The proposed method is validated on modified IEEE 9-bus and 118-bus test achieve a better performance with the consideration of both traditional CM,2 m+1 point estimate method(PEM),Monte Carlo simulation(MCS)and Latin hypercube sampling(LHS)based MCS,the proposed method can achieve a better performance with the consideration of bothcomputational efficiency and accuracy.展开更多
The interconnect temperature of very large scale integration（VLSI） circuits keeps rising due to self-heating and substrate temperature, which can increase the delay and power dissipation of interconnect wires. The t...The interconnect temperature of very large scale integration（VLSI） circuits keeps rising due to self-heating and substrate temperature, which can increase the delay and power dissipation of interconnect wires. The thermal vias are regarded as a promising method to improve the temperature performance of VLSI circuits. In this paper, the extra thermal vias were used to decrease the delay and power dissipation of interconnect wires of VLSI circuits. Two analytical models were presented for interconnect temperature, delay and power dissipation with adding extra dummy thermal vias. The influence of the number of thermal vias on the delay and power dissipation of interconnect wires was analyzed and the optimal via separation distance was investigated. The experimental results show that the adding extra dummy thermal vias can reduce the interconnect average temperature, maximum temperature, delay and power dissipation. Moreover, this method is also suitable for clock signal wires with a large root mean square current.展开更多
为提高Exp-Golomb码的编解码效率,提出了一种基于快速"首位1检测"的Exp-Golomb编解码器硬件实现方法,降低了计算量并节省了硬件资源。该Exp-Golomb编解码器已通过RTL(Register Transfer Level)级仿真和综合,并在FPGA(Field Pr...为提高Exp-Golomb码的编解码效率,提出了一种基于快速"首位1检测"的Exp-Golomb编解码器硬件实现方法,降低了计算量并节省了硬件资源。该Exp-Golomb编解码器已通过RTL(Register Transfer Level)级仿真和综合,并在FPGA(Field Programmable Gate Array)开发平台进行了验证,在133 MHz时钟频率下编解码器的综合门数分别为765门和632门。该编解码器能满足Baseline档次(30帧/s),分辨率为352×288视频序列的实时编解码对质量和速度的要求。展开更多
文摘Guest Editor in Chief:Professor Xiao-Ping Zhang, University of Birmingham The potential for renewable energy to make contributions to mitigating the impact of climate change is expected to increase significantly in the longer term. Renewable energy generation technologies including onshore wind, offshore wind, wave,tidal, marine current, and ocean thermal energy generation as well as PV power generation, which are considered
文摘Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,camera calibration,distortion correction,the semi-automatic high-precision extraction of targets,coordinate systems unification,and bundle adjustment,etc. The relatively convenient construction method of the measuring system can provide an abundant measuring content,a wide measuring range and post processing.The experimental results show that the accuracy of the integral deformation measurement is higher than 0.5 mm and that of the buckling deformation measurement higher than 0.1mm.
基金Supported by Fundamental Research Funds for the Central Universities(SWU1209377)of Southwest UniversityEnterprise Management to Foster Discipline of Rongchang Campus(RCQG207001)of Southwest University
文摘At the background of urban and rural integration,this paper analyzed and discussed factors restricting large-scale farmland operation in China's hilly areas from the qualitative perspective. It recognized large-scale farmland operation on the basis of the long tail theory. Finally,it came up with recommendations for developing large-scale farmland operation in hilly areas.
基金supported by National Science and Technology Major Project(J2019-III-0014-0058)Natural Science Foundation of Science and Technology Department of Shaanxi Province(2022JQ-712)Scientific Research Program of Shaanxi Provincial Education Department(21JK0642)。
文摘Bunsen burner is a typical geometry for investigating the turbulence-flame interaction.In most experimental studies,only turbulence intensity u′and integral scale l0 are used to characterize the turbulent flow field,regardless of the perforation geometry of perforated plates.However,since the geometry influences the developing process and vortex broken,the plate geometry has to be considered when discussing the flame-turbulence interaction.In order to investigate conditions at the same l0 and u′using different geometries,large eddy simulation of CH_(4)/air flames with dynamic TF combustion model was performed.The model validation shows good agreement between Large Eddy Simulation(LES)and experimental results.In the non-reacting flows,the Vortex Stretching of circular-perforated plate condition is always larger than that of slot-perforated plate condition,which comes from the stresses in the flow fields to stretch the vorticity vector.In reacting flows,at the root of the flame,the Vortex Stretching plays a major role,and the total vorticity here of circular-perforated plate condition is still larger(53.8%and 300%larger than that of the slot-perforated plate at x/D=0 and x/D=2.5,respectively).More small-scale vortex in circular-perforated plate condition can affect and wrinkle the flame front to increase the Probability Density Function(PDF)at large curvatures.The 3D curvature distributions of both cases bias to negative values.The negative trend of curvatures at the instant flame front results from the Dilatation term.Also,the value of the Vortex Stretching and the Dilatation at the flame front of circular-perforated plate condition is obviously larger.
基金supported by the National Key Research and Development Program of China(No.2017YFB0903400).
文摘The increasing penetration of wind power brings great uncertainties into power systems,which poses challenges to system planning and operation.This paper proposes a novel probabilistic load flow(PLF)method based on clustering technique to handle large fluctuations from large-scale wind power integration.The traditional cumulant method(CM)for PLF is based on the linearization of load flow equations around the operation point,therefore resulting in significant errors when input random variables have large fluctuations.In the proposed method,the samples of wind power and loads are first generated by the inverse Nataf transformation and then clustered using an improved K-means algorithm to obtain input variable samples with small variances in each cluster.With such pre-processing,the cumulant method can be applied within each cluster to calculate cumulants of output random variables with improved accuracy.The results obtained in each cluster are combined according to the law of total probability to calculate the final cumulants of output random variables for the whole samples.The proposed method is validated on modified IEEE 9-bus and 118-bus test achieve a better performance with the consideration of both traditional CM,2 m+1 point estimate method(PEM),Monte Carlo simulation(MCS)and Latin hypercube sampling(LHS)based MCS,the proposed method can achieve a better performance with the consideration of bothcomputational efficiency and accuracy.
基金Supported by the Guangdong Provincial Natural Science Foundation of China(2014A030313441)the Guangzhou Science and Technology Project(201510010169)+1 种基金the Guangdong Province Science and Technology Project(2016B090918071,2014A040401076)the National Natural Science Foundation of China(61072028)
文摘The interconnect temperature of very large scale integration（VLSI） circuits keeps rising due to self-heating and substrate temperature, which can increase the delay and power dissipation of interconnect wires. The thermal vias are regarded as a promising method to improve the temperature performance of VLSI circuits. In this paper, the extra thermal vias were used to decrease the delay and power dissipation of interconnect wires of VLSI circuits. Two analytical models were presented for interconnect temperature, delay and power dissipation with adding extra dummy thermal vias. The influence of the number of thermal vias on the delay and power dissipation of interconnect wires was analyzed and the optimal via separation distance was investigated. The experimental results show that the adding extra dummy thermal vias can reduce the interconnect average temperature, maximum temperature, delay and power dissipation. Moreover, this method is also suitable for clock signal wires with a large root mean square current.
