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火炮发射冲击载荷对制退机性能的影响研究 被引量:4
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作者 杨玉栋 张培林 +3 位作者 郭化平 田铖 吴晓明 王成 《振动与冲击》 EI CSCD 北大核心 2014年第12期111-116,共6页
为了研究火炮发射冲击载荷对制退机性能的影响,采用超声检测和压力测试相结合的方法分别对人工后坐和实弹射击条件下的制退机性能进行了对比研究。结果表明,火炮后坐结束时非工作腔内不存在传统意义上的真空段,复进时非工作腔提供的液... 为了研究火炮发射冲击载荷对制退机性能的影响,采用超声检测和压力测试相结合的方法分别对人工后坐和实弹射击条件下的制退机性能进行了对比研究。结果表明,火炮后坐结束时非工作腔内不存在传统意义上的真空段,复进时非工作腔提供的液压阻力远小于传统理论计算值,复进节制腔提供的复进液压阻力大于传统理论计算值。当制退机"主流"复进液压阻力系数取拟合值0.036,"支流"复进液压阻力系数取"主流"后坐液压阻力系数的约4.5倍时,复进速度计算结果与火炮实弹射击时的实测复进速度较为吻合;传统方法复进速度计算结果与人工后坐时的实测速度较为一致,传统的非工作腔真空段假设并不适用于有冲击载荷作用的火炮发射过程,据此改进的复进制动图可以更好地指导制退机设计。 展开更多
关键词 制退机 复进计算 液压阻力系数 超声检测 空化 压力测试
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An Approach to Formulation of FNLP with Complex Piecewise Linear Membership Functions 被引量:1
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作者 闻博 李宏光 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第4期411-417,共7页
Traditionally, extra binary variables are demanded to formulate a fuzzy nonlinear programming(FNLP) problem with piecewise linear membership functions(PLMFs). However, this kind of methodology usually suffers increasi... Traditionally, extra binary variables are demanded to formulate a fuzzy nonlinear programming(FNLP) problem with piecewise linear membership functions(PLMFs). However, this kind of methodology usually suffers increasing computational burden associated with formulation and solution, particularly in the face of complex PLMFs. Motivated by these challenges, this contribution introduces a novel approach free of additional binary variables to formulate FNLP with complex PLMFs, leading to superior performance in reducing computational complexity as well as simplifying formulation. A depth discussion about the approach is conducted in this paper, along with a numerical case study to demonstrate its potential benefits. 展开更多
关键词 fuzzy nonlinear programming piecewise linear membership functions MODELING
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Antenna selection based on large-scale fading for distributed MIMO systems
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作者 施荣华 Yuan Zexi +2 位作者 Dong Jian Lei Wentai Peng Chunhua 《High Technology Letters》 EI CAS 2016年第3期233-240,共8页
An antenna selection algorithm based on large-scale fading between the transmitter and receiver is proposed for the uplink receive antenna selection in distributed multiple-input multiple-output(D-MIMO) systems. By ut... An antenna selection algorithm based on large-scale fading between the transmitter and receiver is proposed for the uplink receive antenna selection in distributed multiple-input multiple-output(D-MIMO) systems. By utilizing the radio access units(RAU) selection based on large-scale fading,the proposed algorithm decreases enormously the computational complexity. Based on the characteristics of distributed systems,an improved particle swarm optimization(PSO) has been proposed for the antenna selection after the RAU selection. In order to apply the improved PSO algorithm better in antenna selection,a general form of channel capacity was transformed into a binary expression by analyzing the formula of channel capacity. The proposed algorithm can make full use of the advantages of D-MIMO systems,and achieve near-optimal performance in terms of channel capacity with low computational complexity. 展开更多
关键词 distributed MIMO systems antenna selection particle swarm optimization large-scale fading
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Binary Image Watermarking Algorithm Using Matrix of Complexity Index
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作者 张帆 张军亮 沈夏炯 《Journal of Shanghai Jiaotong university(Science)》 EI 2008年第6期651-654,共4页
A new watermarking algorithm of binary image is proposed.The complexity index of pixels is presented to reflect the change degree of pixels and to evaluate the modifiable degree of pixels.Firstly, in a small image blo... A new watermarking algorithm of binary image is proposed.The complexity index of pixels is presented to reflect the change degree of pixels and to evaluate the modifiable degree of pixels.Firstly, in a small image block, the complexity index of"jumping-change"is calculated in vertical and horizontal direction.Secondly, the matrix of the complexity index is calculated by integrating the complexity index of pixels in two directions.Finally, the matrix of the complexity index is used to embed the watermark in binary images.Experimental results show that the proposed algorithm has a good performance. 展开更多
关键词 binary image WATERMARK complexity index complexity index matrix
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Theoretical modeling of steel reinforced ECC column under eccentric compressive loading 被引量:4
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作者 PAN JinLong GU Jie CHEN JunHan 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2015年第5期889-898,共10页
Fiber reinforced cementitious composites(ECC) are a class of advanced composites with strain hardening and multiple cracking behaviors. Substitution of concrete with ECC can significantly improve the seismic resistanc... Fiber reinforced cementitious composites(ECC) are a class of advanced composites with strain hardening and multiple cracking behaviors. Substitution of concrete with ECC can significantly improve the seismic resistance and durability of the infrastructures. In this paper, it is proposed to use ECC as the matrix of frame columns for improving its load carrying capacity, ductility, and avoiding the brittleness of concrete. Based on the assumption of plane remaining plane and constitutive models of materials, theoretical models for calculating the load-carrying capacity of the steel reinforced ECC columns under small and large eccentric compression are proposed. With the parameters of the constitutive models from the existing experimental data, the relationship between ultimate axial load and moment capacities is also derived with the proposed models. To verify the validity of the proposed theoretical models, finite element analysis with the software of ATENA is conducted to simulate the mechanical behavior of the steel reinforced ECC columns under eccentric compressive loading. The calculation results from the theoretical models show good consistency with the simulated results, indicating that the proposed models are feasible and reliable for design. Finally, based on the theoretical models, the effect of the ultimate tensile strain and compressive strength of ECC, longitudinal reinforcement ratio on the load carrying capacity of the steel reinforced ECC column are comprehensively studied. 展开更多
关键词 compressive reinforced ultimate durability constitutive reinforcement tensile columns carrying calculating
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