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REVO测头在非正交式三坐标测量机中的探测矢量修正算法 被引量:5
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作者 刘书桂 张海涛 苏智琨 《天津大学学报(自然科学与工程技术版)》 EI CSCD 北大核心 2016年第9期956-960,共5页
REVO测头是基于正交式三坐标测量机设计和应用的,针对在非正交悬臂式整体叶盘原位测量机下应用REVO测头探测姿态不正确的问题,根据悬臂式测量机的结构特点,提出了一种探测矢量修正算法,通过将控制器返回的数据进行分离,并经过建立的旋... REVO测头是基于正交式三坐标测量机设计和应用的,针对在非正交悬臂式整体叶盘原位测量机下应用REVO测头探测姿态不正确的问题,根据悬臂式测量机的结构特点,提出了一种探测矢量修正算法,通过将控制器返回的数据进行分离,并经过建立的旋转臂与测头之间的准刚体模型变换,得到REVO测头探测矢量与机器坐标系下被测工件表面法矢的关系,达到探测矢量修正的目的.实验结果表明:探测矢量经过修正后,测量30,mm长的量块,平均误差值从0.015,6,mm降低到0.003,7,mm,提高了测量机的测量精度,为REVO测头在非正交式三坐标测量机中的应用和深入研究奠定了坚实的基础. 展开更多
关键词 整体叶盘 非正交式三坐标测量机 REVO测头 探测矢量修
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非正交坐标测量机下REVO测头参数及误差标定 被引量:1
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作者 张海涛 刘书桂 +1 位作者 李杏华 苏智琨 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2017年第10期50-54,共5页
针对基于正交式坐标测量机设计和应用的REVO五轴测量系统,在非正交式坐标测量机下应用不能实现自标定的问题,基于对称和反转原理,提出了测头参数和误差项的一系列单项标定方法,通过测量机单轴小范围辅助运动测量量块,实现了非正交坐标... 针对基于正交式坐标测量机设计和应用的REVO五轴测量系统,在非正交式坐标测量机下应用不能实现自标定的问题,基于对称和反转原理,提出了测头参数和误差项的一系列单项标定方法,通过测量机单轴小范围辅助运动测量量块,实现了非正交坐标测量机下REVO测头的参数和误差标定,避免了大范围运动测量机主轴所产生的运动误差给标定结果带来的影响.通过实验验证了所提出标定方法的精确性和有效性,经过标定和误差补偿后,平均测量误差从18.1μm降低到了0.8μm.实验结果表明:所提出的方法操作简便,精确度高,具有很好的溯源性. 展开更多
关键词 非正交式 坐标测量机 REVO测头 参数与误差项 标定
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认知无线电非正交多址接入随机网络物理层安全性能分析 被引量:7
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作者 于宝泉 蔡跃明 胡健伟 《电子与信息学报》 EI CSCD 北大核心 2020年第4期950-956,共7页
该文针对干扰源以及窃听节点均随机分布的通信场景,分析了认知无线电启发式非正交多址接入(CRNOMA)网络中次用户通信对的安全通信性能。采用随机几何理论,将窃听节点和干扰节点建模为服从特定分布的齐次泊松点过程(PPP)。首先,在保证主... 该文针对干扰源以及窃听节点均随机分布的通信场景,分析了认知无线电启发式非正交多址接入(CRNOMA)网络中次用户通信对的安全通信性能。采用随机几何理论,将窃听节点和干扰节点建模为服从特定分布的齐次泊松点过程(PPP)。首先,在保证主用户通信对通信可靠性的前提下,得到了发端设定的功率分配系数,进一步得到了次用户通信对的连接中断概率和安全中断概率的闭式表达式。随后,得到了功率分配系数随主用户可靠性能约束的变化规律。最后,研究了次用户对的中断概率随着窃听节点密度、发端发送功率的变化情况,结果表明干扰信号的增强在降低网络可靠性能的同时,换来了安全性能的提高。仿真结果验证了理论分析的正确性。 展开更多
关键词 认知无线电 物理层安全 启发多址接入 随机分布 功率分配
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REVO五轴测量系统重构与建模方法研究 被引量:1
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作者 张海涛 刘书桂 +1 位作者 李杏华 苏智琨 《天津大学学报(自然科学与工程技术版)》 EI CSCD 北大核心 2017年第7期753-757,共5页
REVO五轴测量系统是基于正交式坐标测量机设计和应用的高效率、高精度测量系统.针对在非正交式坐标测量机环境下应用REVO五轴测量系统,提出了REVO五轴测量系统的重构与数学模型.建立了REVO五轴测量系统原始返回数据的构成模型,从返回的... REVO五轴测量系统是基于正交式坐标测量机设计和应用的高效率、高精度测量系统.针对在非正交式坐标测量机环境下应用REVO五轴测量系统,提出了REVO五轴测量系统的重构与数学模型.建立了REVO五轴测量系统原始返回数据的构成模型,从返回的合成数据中分离出光栅数据;基于准刚体理论,建立了REVO测头误差补偿模型.通过实验验证了误差补偿模型的正确性和有效性,经过误差补偿,测量误差平均值从-0.190,3,mm降低到0.001,1,mm.本文的研究内容对于在非正交式坐标测量机下应用REVO五轴测量系统具有重要意义. 展开更多
关键词 非正交式坐标测量机 REVO测头 数据分离 建模 误差补偿
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基于统计模型的结构损伤识别 被引量:10
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作者 黄斌 史文海 《工程力学》 EI CSCD 北大核心 2006年第12期47-52,18,共7页
提出了一种基于递推随机有限元方法(RSFEM)的随机结构损伤识别方法。在定义了随机损伤指数概念的基础上,考虑模型误差的不确定性和测量噪声的影响,建立了关于随机损伤指数的控制方程。然后,利用RSFEM得到了结构随机损伤指数的统计特性... 提出了一种基于递推随机有限元方法(RSFEM)的随机结构损伤识别方法。在定义了随机损伤指数概念的基础上,考虑模型误差的不确定性和测量噪声的影响,建立了关于随机损伤指数的控制方程。然后,利用RSFEM得到了结构随机损伤指数的统计特性。数值算例的结果显示,新的方法能在考虑模型误差和测量噪声的情况下对结构损伤进行有效识别,且在结构随机参数有较大涨落情况下,该方法仍能有效识别出结构损伤,识别结果与蒙特卡洛模拟解非常吻合。 展开更多
关键词 随机结构 损伤识别 统计模型 递推随机有限元 多项
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随机结构重特征值分析的递推随机有限元法 被引量:2
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作者 黄斌 刘文军 《振动工程学报》 EI CSCD 北大核心 2006年第2期156-160,共5页
利用递推随机有限元方法研究了具有随机参数结构的重特征值问题。采用随机收敛的非正交多项式展式表示未知的随机重特征值和随机特征向量,建立了和摄动法类似的一系列确定的递推方程,通过求解这些递推方程,得到了重特征值的统计值。算... 利用递推随机有限元方法研究了具有随机参数结构的重特征值问题。采用随机收敛的非正交多项式展式表示未知的随机重特征值和随机特征向量,建立了和摄动法类似的一系列确定的递推方程,通过求解这些递推方程,得到了重特征值的统计值。算例表明,同基于二阶泰勒展开的摄动随机有限元法相比,递推随机有限元法的结果能在较宽的随机涨落范围内更好地逼近蒙特卡洛模拟结果。 展开更多
关键词 随机振动 重特征值 有限元方法 多项 摄动法
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多种概率分布的随机参数结构屈曲特征值分析 被引量:1
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作者 史文海 李正农 黄斌 《武汉理工大学学报(交通科学与工程版)》 2007年第2期348-351,共4页
采用随机收敛的非正交的多项式展式表示未知的随机屈曲特征对,对随机结构的随机变量在服从多种概率分布情况下的屈曲特征值进行了研究.算例表明,对于服从多种概率分布的随机结构屈曲特征值问题,当参数变异性较大时,即使只采用前4阶非正... 采用随机收敛的非正交的多项式展式表示未知的随机屈曲特征对,对随机结构的随机变量在服从多种概率分布情况下的屈曲特征值进行了研究.算例表明,对于服从多种概率分布的随机结构屈曲特征值问题,当参数变异性较大时,即使只采用前4阶非正交多项式展式,逼近的结果仍然较好.计算结果还表明,如果把非高斯分布的随机参数模型用高斯分布模型进行分析,将给研究带来相当大的误差,而且这种误差随参数变异性的增大而增大. 展开更多
关键词 递推求解方法 随机结构 多项 摄动法 屈曲特征值
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随机结构弹性屈曲的递推求解方法 被引量:1
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作者 黄斌 史文海 《工程力学》 EI CSCD 北大核心 2006年第8期36-41,共6页
采用随机收敛的非正交的多项式展式表示未知的随机屈曲特征值和屈曲模态,利用摄动技巧,建立了随机结构弹性屈曲的递推求解方法。算例表明,和基于泰勒展开的摄动随机有限元方法相比,方法的结果能在较宽的随机涨落范围内更好地逼近蒙特卡... 采用随机收敛的非正交的多项式展式表示未知的随机屈曲特征值和屈曲模态,利用摄动技巧,建立了随机结构弹性屈曲的递推求解方法。算例表明,和基于泰勒展开的摄动随机有限元方法相比,方法的结果能在较宽的随机涨落范围内更好地逼近蒙特卡洛模拟结果,即使只采用前四阶非正交多项式展式,逼近的结果仍然较好。 展开更多
关键词 随机结构 多项 摄动随机有限元法 屈曲特征值 递推求解方法
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REFINED HYBRID MINDLIN PLATE ELEMENT FOR GEOMETRICALLY NON LINEAR ANALYSIS
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作者 郑世杰 陶宝祺 陈万吉 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2000年第1期90-94,共5页
Based upon a generalized variational principle, which relaxed the inter element continuity requirements, a novel refined hybrid Mindlin plate element is developed, its non linear element stiffness matrices are decom... Based upon a generalized variational principle, which relaxed the inter element continuity requirements, a novel refined hybrid Mindlin plate element is developed, its non linear element stiffness matrices are decomposed into a series of matrices with respect to the assumed strain modes. The formulation presented in this paper is different from any other non linear mixed/hybrid element formulation all successful experience of linear hybrid formulation is absorbed into the formulation(adding non conforming modes and realizing orthogonalization) Numerical results show that the present approach is more effective than any other non linear hybrid element formulation over the accuracy and computational efficiency. In addition, non conforming modes can also overcome the shear locking effect. 展开更多
关键词 non linear mechanics non conforming mode orthogonal approach geometrically non linear refined element
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Approximation to NLAR(p) with Wavelet Neural Networks
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作者 朱石焕 吴曦 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第4期94-98,共5页
Recently, wavelet neural networks have become a popular tool for non-linear functional approximation. Wavelet neural networks, which basis functions are orthonormal scalling functions, are more suitable in approximati... Recently, wavelet neural networks have become a popular tool for non-linear functional approximation. Wavelet neural networks, which basis functions are orthonormal scalling functions, are more suitable in approximating to function. Based on it, approximating to NLAR(p) with wavelet neural networks is studied. 展开更多
关键词 wavelet neural networks orthonormal scaling functions NLAR(p)
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Free vibration analysis of non-homogeneous orthotropic plates resting on Pasternak elastic foundation by Rayleigh-Ritz method 被引量:1
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作者 Ahmad Rahbar-Ranji Arash Shahbaztabar 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第2期413-420,共8页
Free vibration analysis of non-homogeneous orthotropic plates resting on a Pasternak type of elastic foundation is investigated. A set of admissible orthogonal polynomials are generated with Gram-Schmidt orthogonaliza... Free vibration analysis of non-homogeneous orthotropic plates resting on a Pasternak type of elastic foundation is investigated. A set of admissible orthogonal polynomials are generated with Gram-Schmidt orthogonalization procedure and adopted in the Rayleigh-Ritz method. Accuracy and applicability of the method are examined by comparison of the results for different boundary conditions and material types with those available in literature. It is found that this method has good accuracy regardless of type of boundary condition and yields very accurate results even with low number of terms of orthogonal polynomials for the first mode of vibration. For higher modes of vibration, higher terms of orthogonal polynomials should be used. The effects of foundation parameter, density and non-homogeneity parameters on natural frequency are examined. It is concluded that natural frequency of plates are more sensitive to shearing layer coefficient rather than Winkler coefficient and density parameter has weakening effect on natural frequency. 展开更多
关键词 free vibration non-homogeneous orthotropic plate Pastemak foundation Rayleigh-Ritz method Gram-Schmidt procedure
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Development of practical postprocessor for 5-axis machine tool with non-orthogonal rotary axes 被引量:13
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作者 JUNG Hyoun-Chul HWANG Jong-Dae +1 位作者 PARK Ki-Beom JUNG Yoon-Gyo 《Journal of Central South University》 SCIE EI CAS 2011年第1期159-164,共6页
In order to develop a practical postprocessor for 5-axis machine tool,the general equations of numerically controlled(NC) data for 5-axis configurations with non-orthogonal rotary axes were exactly expressed by the in... In order to develop a practical postprocessor for 5-axis machine tool,the general equations of numerically controlled(NC) data for 5-axis configurations with non-orthogonal rotary axes were exactly expressed by the inverse kinematics,and a windows-based postprocessor written with Visual Basic was developed according to the proposed algorithm.The developed postprocessor is a general system suitable for all kinds of 5-axis machines with orthogonal and non-orthogonal rotary axes.Through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment,the effectiveness of the proposed algorithm is confirmed.Compatibility is improved by allowing exchange of data formats such as rotational total center position(RTCP) controlled NC data,vector post NC data,and program object file(POF) cutter location(CL) data,and convenience is increased by adding the function of work-piece origin offset.Consequently,a practical post-processor for 5-axis machining is developed. 展开更多
关键词 post-processor 5-axis machining non-orthogonal rotary axes numerically controlled (NC) data CL data
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Channel Capacity of DWDM Networks with Cross-phase Modulation Effect
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作者 QI Jun-xuan WEN Shuang-cun 《Semiconductor Photonics and Technology》 CAS 2006年第1期51-53,共3页
In dense wavelength division multiplexing(DWDM) optical transmission systems, cross phase modulation(XPM) due to Kerr effect causes phase shift and intensity modulation in each channel, which will lead the channel cap... In dense wavelength division multiplexing(DWDM) optical transmission systems, cross phase modulation(XPM) due to Kerr effect causes phase shift and intensity modulation in each channel, which will lead the channel capacity to be a random variable. An expression of the channel capacity dealing with XPM effect is presented, and the correctness and accuracy of this method are demonstrated by numerical simulation. 展开更多
关键词 Fiber nonlinearity Information theory Optical fiber communication systems Cross-phase modulation
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A New Differential Quadrature Methodology Based on Bernstein Polynomials for Solving the Equations Governing the Unsteady Flow of a Polytropic Gas
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作者 Abdul-Sattar J. A1-Saif Firas A. Al-Saadawi 《Journal of Physical Science and Application》 2015年第1期38-47,共10页
Aims of this paper are to improve ADI differential quadrature method (ADI-DQM) based on Bernstein polynomials and add a new application to the differential quadrature method. By using the new methodology, the numeri... Aims of this paper are to improve ADI differential quadrature method (ADI-DQM) based on Bernstein polynomials and add a new application to the differential quadrature method. By using the new methodology, the numerical solutions of the governing equations of unsteady two-dimensional flow of a polytropic gas are investigated. The numerical results reveal that the new technique is very effective and gives high accuracy, good convergence and reasonable stability. 展开更多
关键词 Differential quadrature method polytropic gas Bemstein polynomial ADI accuracy.
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Enhanced uplink non-orthogonal multiple access for 5G and beyond systems
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作者 Wen-jia LIU Xiao-lin HOU Lan CHEN 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2018年第3期340-356,共17页
Uplink non-orthogonM multiple access (NOMA) is a promising technique to meet the requirements of the fifth generation (5G) and beyond systems. Various NOMA schemes have been proposed in both academia and industry.... Uplink non-orthogonM multiple access (NOMA) is a promising technique to meet the requirements of the fifth generation (5G) and beyond systems. Various NOMA schemes have been proposed in both academia and industry. However, most existing schemes assume equal average received power, which limits the performance. We propose three enhancements of uplink NOMA to achieve the requirements of massive connectivity and high reliability in 5G, where unequal average received power is exploited as part of the multiple access signature. First, the optimal sequences targeting to generalized Welch-bound equality (GWBE) are obtained for unequal average received power. Then user grouping with multi-level received powers is proposed for better successive interference cancellation (SIC) at the receiver. Finally, sequence grouping based on the cross-correlation properties of sequences is proposed to reduce inter-and intra-group interference. Simulation results show that by incorporating multi-level received powers and sequence grouping into existing NOMA schemes, for an NOMA system with 400% overloading and fixed signature allocation, 3 dB and 10 dB signal-to-noise ratio (SNR) gains at 0.1 block error rate (BLER) target can be achieved compared with existing NOMA schemes and orthogonal multiple access (OMA), respectively. Besides, 0.01 BLER target can be achieved while an error floor exists in existing NOMA schemes. Under random sequence selection, collision probability is reduced by multi-level powers. In addition, GWBE sequences achieve lower BLER than existing sequences and the gain is large especially for low BLER requirements. This shows that the proposed scheme can support larger connectivity and higher reliability. 展开更多
关键词 Uplink non-orthogonal multiple access Generalized Welch-bound equality Multi-level received powers Sequence grouping
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