Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.A...Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.展开更多
为进一步提高压缩感知重构算法的重构成功率和重构精度,从原子匹配准则和预选阶段原子选择方式的角度出发,提出一种基于Dice系数的弱选择回溯匹配追踪(weak-selection backtracking matching pursuit based on Dice coefficient,DWBMP)...为进一步提高压缩感知重构算法的重构成功率和重构精度,从原子匹配准则和预选阶段原子选择方式的角度出发,提出一种基于Dice系数的弱选择回溯匹配追踪(weak-selection backtracking matching pursuit based on Dice coefficient,DWBMP)算法.首先,采用Dice系数匹配准则度量两个向量之间的相似性,选出最匹配的原子,以优化支撑集;然后,结合回溯思想和弱选择思想剔除相似性较小的原子,完成预选阶段原子的二次筛选.MATLAB仿真结果显示,相同条件下,DWBMP算法较经典的压缩感知重构算法具有更优的重构精度和重构成功率.展开更多
Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the...Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.展开更多
In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship...In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.展开更多
为提升欠定盲源分离问题中混合矩阵的估计精度,在噪声环境下基于密度的空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法的基础上,提出一种自适应确定输入参数的DBSCAN算法(adaptive DBSCAN,A-DBSCAN...为提升欠定盲源分离问题中混合矩阵的估计精度,在噪声环境下基于密度的空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法的基础上,提出一种自适应确定输入参数的DBSCAN算法(adaptive DBSCAN,A-DBSCAN)用于混合矩阵估计。针对DBSCAN算法邻域半径(Eps)及邻域点数(MinPts)依赖人为设定的问题,首先利用曲线拟合方法得出Eps,然后通过分析聚类输出类别数与噪声点数关系确定MinPts,并将其与混合矩阵估计模型相结合,最后通过最短路径算法实现源信号恢复。实验结果表明,提出的算法在估计混合矩阵和恢复源信号时,相关性能与对比算法相较均有明显提升。展开更多
文摘Pulsed power technology,whereas the electrical energy stored in a relative long period is released in much shorter timescale,is an efficient method to create high energy density physics(HEDP)conditions in laboratory.Around the beginning of this century,China Academy of Engineering Physics(CAEP)began to build some experimental facilities for HEDP investigations,among which the Primary Test Stand(PTS),a multi-module pulsed power facility with a nominal current of 10 MA and a current rising time~90 ns,is an important achievement on the roadmap of the electro-magnetically driven inertial confinement fusion(ICF)researches.PTS is the first pulsed power facility beyond 10 TW in China.Therefore,all the technologies have to be demonstrated,and all the engineering issues have to be overcome.In this article,the research outline,key technologies and the preliminary HEDP experiments are reviewed.Prospects on HEDP research on PTS and pulsed power development for the next step are also discussed.
文摘为进一步提高压缩感知重构算法的重构成功率和重构精度,从原子匹配准则和预选阶段原子选择方式的角度出发,提出一种基于Dice系数的弱选择回溯匹配追踪(weak-selection backtracking matching pursuit based on Dice coefficient,DWBMP)算法.首先,采用Dice系数匹配准则度量两个向量之间的相似性,选出最匹配的原子,以优化支撑集;然后,结合回溯思想和弱选择思想剔除相似性较小的原子,完成预选阶段原子的二次筛选.MATLAB仿真结果显示,相同条件下,DWBMP算法较经典的压缩感知重构算法具有更优的重构精度和重构成功率.
基金Project(51974278)supported by the National Natural Science Foundation of ChinaProject(E2018203446)supported by the Natural Science Foundation of Hebei Province Distinguished Young Fund Project,ChinaProject(2018YFA0707303)supported by the National Key Research and Development Project of China。
文摘Unequal diameter twin-roll casting(UDTRC)can improve the formability,surface conditions,and production efficiency during the fabrication of clad strips.Using Fluent software,a numerical simulation is used to study the asymmetric heat transfer characteristics of Cu/Al clad strips fabricated by UDTRC.The effects of roller velocity ratio,Cu strip thickness,and inclination angle on the kissing point position,as well as the entire temperature distribution are obtained.The heat transfer model is established,and the mechanism is discussed.The Cu strip and rollers are found to be the main causes of asymmetric heat transfer,indicating that the roller velocity ratio changes the liquid zone proportion in the molten pool.The Cu strip thickness determines the heat absorption capacity and the variations in thermal resistance between the molten Al and the big roller.The inclination angle of the small roller changes the cooling time of big roller to molten Al.Moreover,the microstructure of Al cladding under different roller velocity ratios is examined.The results show significant grain refinement caused by the shear strain along the thickness direction of Al cladding and the intense heat transfer at the moment of contact between the metal Al cladding and Cu strip.
基金supported by the National Natural Science Foundation of China(6167309361370152)the Science and Technology Project of Shenyang(F16-205-1-01)
文摘In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.
文摘为提升欠定盲源分离问题中混合矩阵的估计精度,在噪声环境下基于密度的空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法的基础上,提出一种自适应确定输入参数的DBSCAN算法(adaptive DBSCAN,A-DBSCAN)用于混合矩阵估计。针对DBSCAN算法邻域半径(Eps)及邻域点数(MinPts)依赖人为设定的问题,首先利用曲线拟合方法得出Eps,然后通过分析聚类输出类别数与噪声点数关系确定MinPts,并将其与混合矩阵估计模型相结合,最后通过最短路径算法实现源信号恢复。实验结果表明,提出的算法在估计混合矩阵和恢复源信号时,相关性能与对比算法相较均有明显提升。
