Aim To investigate the spray particle velocity and its distribution characteristics. Methods\ A set of PIV (particle image velocimetry) system was developed and used to observe and analyze the spray particle velocity...Aim To investigate the spray particle velocity and its distribution characteristics. Methods\ A set of PIV (particle image velocimetry) system was developed and used to observe and analyze the spray particle velocity field. Results and Conclusion\ Double exposure image of the spray particle within the region of 10-50 mm from the nozzle tip was recorded and analyzed by the IBAS2000 analysis system. Some characteristics of the spray particle velocity and its distribution were obtained.展开更多
传统对含缺陷管道失效应力的预测方法存在误差偏大的问题。针对该问题,利用MATLAB软件建立基于PSO–GPR(particle swarm optimization–Gaussian process regression)含缺陷管道失效应力预测模型。通过对60组含缺陷管道的试验数据进行测...传统对含缺陷管道失效应力的预测方法存在误差偏大的问题。针对该问题,利用MATLAB软件建立基于PSO–GPR(particle swarm optimization–Gaussian process regression)含缺陷管道失效应力预测模型。通过对60组含缺陷管道的试验数据进行测试,发现预测结果与实测结果均在95%置信区间内,表明可以将均值作为预测结果。对预测结果进行分析表明:高斯过程回归的预测结果与实测结果的最小相对误差为0.003%,最大相对误差为1.205%,平均相对误差为0.319%,基于预测结果和实测结果的散点均落在曲线y=x的±1.3%误差带中,验证了高斯过程回归预测模型的准确性,为管道的工程实际应用与维修提供较为精准的判断依据。展开更多
Big Data applications face different types of complexities in classifications.Cleaning and purifying data by eliminating irrelevant or redundant data for big data applications becomes a complex operation while attempt...Big Data applications face different types of complexities in classifications.Cleaning and purifying data by eliminating irrelevant or redundant data for big data applications becomes a complex operation while attempting to maintain discriminative features in processed data.The existing scheme has many disadvantages including continuity in training,more samples and training time in feature selections and increased classification execution times.Recently ensemble methods have made a mark in classification tasks as combine multiple results into a single representation.When comparing to a single model,this technique offers for improved prediction.Ensemble based feature selections parallel multiple expert’s judgments on a single topic.The major goal of this research is to suggest HEFSM(Heterogeneous Ensemble Feature Selection Model),a hybrid approach that combines multiple algorithms.The major goal of this research is to suggest HEFSM(Heterogeneous Ensemble Feature Selection Model),a hybrid approach that combines multiple algorithms.Further,individual outputs produced by methods producing subsets of features or rankings or voting are also combined in this work.KNN(K-Nearest Neighbor)classifier is used to classify the big dataset obtained from the ensemble learning approach.The results found of the study have been good,proving the proposed model’s efficiency in classifications in terms of the performance metrics like precision,recall,F-measure and accuracy used.展开更多
本文介绍了二维PIC(Particle in cell)方法,这种方法常用于粒子动力学模拟中空间电荷作用的计算。并比较了以时间为自变量(t-code)和以纵向位置为自变量(z-code)的两种动力学模拟程序;针对“国家重点基础研究发展规划”洁净核能项目中...本文介绍了二维PIC(Particle in cell)方法,这种方法常用于粒子动力学模拟中空间电荷作用的计算。并比较了以时间为自变量(t-code)和以纵向位置为自变量(z-code)的两种动力学模拟程序;针对“国家重点基础研究发展规划”洁净核能项目中的射频四极(RFQ)加速器结构参数,给出了单束加速和正、负离子束同时加速两种情况下,t-code和z-code模拟得出的传输效率。结果表明,当束团的相位宽度大或能散大时,z-code 在计算空间电荷作用时会引入相对较大的误差,从而应该使用t-code来进行动力学模拟,以获得更准确的结果。展开更多
For the purpose of improving turbine efficiency,a detailed investigation of flow field near rim seal region in the main annulus is absolutely essential.Purge flow egressed from the seal gap penetrates the hub boundary...For the purpose of improving turbine efficiency,a detailed investigation of flow field near rim seal region in the main annulus is absolutely essential.Purge flow egressed from the seal gap penetrates the hub boundary layer and travels along with the secondary flow in the main path.The propagation of the purge flow and its influence on the turbine performance are crucial and cannot be neglected in the aerodynamic and thermal design.In addition,the interaction of vane wake and blade potential field also has a significant impact on the turbine stage performance.In this study,flow field between inlet guide vanes(IGV)and rotor blades was experimentally investigated at specific positions with the help of a two-dimensional particle image velocimetry(2-D PIV).A phase-locking technique was also employed to capture the images of flow field at different rotor blade positions.Data acquired characterizes the impact of emergent purge flow on the flow structures within the main annulus.The impacts of vane wake and blade potential field on the flow fields were analyzed through characterizations provided by the time-averaged field results.Finally,flow fields at different main flow rates and under different seal gap widths were also presented and assessed.展开更多
文摘Aim To investigate the spray particle velocity and its distribution characteristics. Methods\ A set of PIV (particle image velocimetry) system was developed and used to observe and analyze the spray particle velocity field. Results and Conclusion\ Double exposure image of the spray particle within the region of 10-50 mm from the nozzle tip was recorded and analyzed by the IBAS2000 analysis system. Some characteristics of the spray particle velocity and its distribution were obtained.
文摘传统对含缺陷管道失效应力的预测方法存在误差偏大的问题。针对该问题,利用MATLAB软件建立基于PSO–GPR(particle swarm optimization–Gaussian process regression)含缺陷管道失效应力预测模型。通过对60组含缺陷管道的试验数据进行测试,发现预测结果与实测结果均在95%置信区间内,表明可以将均值作为预测结果。对预测结果进行分析表明:高斯过程回归的预测结果与实测结果的最小相对误差为0.003%,最大相对误差为1.205%,平均相对误差为0.319%,基于预测结果和实测结果的散点均落在曲线y=x的±1.3%误差带中,验证了高斯过程回归预测模型的准确性,为管道的工程实际应用与维修提供较为精准的判断依据。
文摘Big Data applications face different types of complexities in classifications.Cleaning and purifying data by eliminating irrelevant or redundant data for big data applications becomes a complex operation while attempting to maintain discriminative features in processed data.The existing scheme has many disadvantages including continuity in training,more samples and training time in feature selections and increased classification execution times.Recently ensemble methods have made a mark in classification tasks as combine multiple results into a single representation.When comparing to a single model,this technique offers for improved prediction.Ensemble based feature selections parallel multiple expert’s judgments on a single topic.The major goal of this research is to suggest HEFSM(Heterogeneous Ensemble Feature Selection Model),a hybrid approach that combines multiple algorithms.The major goal of this research is to suggest HEFSM(Heterogeneous Ensemble Feature Selection Model),a hybrid approach that combines multiple algorithms.Further,individual outputs produced by methods producing subsets of features or rankings or voting are also combined in this work.KNN(K-Nearest Neighbor)classifier is used to classify the big dataset obtained from the ensemble learning approach.The results found of the study have been good,proving the proposed model’s efficiency in classifications in terms of the performance metrics like precision,recall,F-measure and accuracy used.
文摘本文介绍了二维PIC(Particle in cell)方法,这种方法常用于粒子动力学模拟中空间电荷作用的计算。并比较了以时间为自变量(t-code)和以纵向位置为自变量(z-code)的两种动力学模拟程序;针对“国家重点基础研究发展规划”洁净核能项目中的射频四极(RFQ)加速器结构参数,给出了单束加速和正、负离子束同时加速两种情况下,t-code和z-code模拟得出的传输效率。结果表明,当束团的相位宽度大或能散大时,z-code 在计算空间电荷作用时会引入相对较大的误差,从而应该使用t-code来进行动力学模拟,以获得更准确的结果。
基金funded by the National Natural Science Foundation of China(Grant No.51776011)National Science and Technology Major Project(2017-V-0016-0068)。
文摘For the purpose of improving turbine efficiency,a detailed investigation of flow field near rim seal region in the main annulus is absolutely essential.Purge flow egressed from the seal gap penetrates the hub boundary layer and travels along with the secondary flow in the main path.The propagation of the purge flow and its influence on the turbine performance are crucial and cannot be neglected in the aerodynamic and thermal design.In addition,the interaction of vane wake and blade potential field also has a significant impact on the turbine stage performance.In this study,flow field between inlet guide vanes(IGV)and rotor blades was experimentally investigated at specific positions with the help of a two-dimensional particle image velocimetry(2-D PIV).A phase-locking technique was also employed to capture the images of flow field at different rotor blade positions.Data acquired characterizes the impact of emergent purge flow on the flow structures within the main annulus.The impacts of vane wake and blade potential field on the flow fields were analyzed through characterizations provided by the time-averaged field results.Finally,flow fields at different main flow rates and under different seal gap widths were also presented and assessed.
