As the Welch-Berlekamp (W-B) theorem accurately predicts structure of error locator polynomials of the error patterns, it results in the Welch-Berlekamp algorithm of decoding cyclic codes. However, it is only valid wi...As the Welch-Berlekamp (W-B) theorem accurately predicts structure of error locator polynomials of the error patterns, it results in the Welch-Berlekamp algorithm of decoding cyclic codes. However, it is only valid within the BCH bound. Now, a prediction formula for error locator determination is presented based on the study of theory of minimal homogeneous interpolation problem, which extends the Welch-Berlekamp theorem and expands the Welch-Berlekamp algorithm so that the constraint from the BCH展开更多
In this paper, we further study the connections between linear network error correction codes and representable matroids. We extend the concept of matroidal network introduced by Dougherty et al. to a generalized case...In this paper, we further study the connections between linear network error correction codes and representable matroids. We extend the concept of matroidal network introduced by Dougherty et al. to a generalized case when errors occur in multi- ple channels. Importantly, we show the necessary and sufficient conditions on the existence of linear network error correction mul- ticast/broadcast/dispersion maximum distance separable （MDS） code on a matroidal error correction network.展开更多
By extending the notion of the minimum distance for linear network error correction code(LNEC), this paper introduces the concept of generalized minimum rank distance(GMRD) of variable-rate linear network error correc...By extending the notion of the minimum distance for linear network error correction code(LNEC), this paper introduces the concept of generalized minimum rank distance(GMRD) of variable-rate linear network error correction codes. The basic properties of GMRD are investigated. It is proved that GMRD can characterize the error correction/detection capability of variable-rate linear network error correction codes when the source transmits the messages at several different rates.展开更多
As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between ...As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between the corresponding wax pattern and the internal ceramic core.However, due to locating errors, the actual position of ceramic core is always deviated from the ideal position, which makes it difficult to guarantee the wall-thickness precision of the wax pattern.To solve this problem, a wall-thickness compensation strategy is proposed in this paper. Firstly,based on the industrial computed tomography(ICT) technique and curve matching algorithms, a model reconstruction method is developed, with which the 3D model of a trial wax pattern can be easily constructed. After that, focusing on eliminating the wall-thickness errors of the trial wax pattern, an optimization method for the pose of the ceramic core in the wax pattern is proposed. Then, by mapping the optimal pose of the ceramic core to length adjustments of the locating rods, the wall-thickness errors of the wax pattern can be greatly reduced. A case study is also given to illustrate the effectiveness of the proposed compensation strategy.展开更多
The plane wave spectrum surface integration (PWS SI) is a practical and efficient method for antenna radome system analysis, especially for determining the boresight error (BSE) in the system. But it is only used f...The plane wave spectrum surface integration (PWS SI) is a practical and efficient method for antenna radome system analysis, especially for determining the boresight error (BSE) in the system. But it is only used for sum pattern calculation till now, and BSE is calculated by the beam maximum searching method. In this paper, the aperture distribution for difference pattern is formulated as the product of that for sum pattern and a two dimensional periodic window function. A series representation for the spectrum of difference pattern is then obtained according to the convolution theorem. The truncation error of the series has been analyzed by introducing the coverage radius of the spectrum of sum pattern. Based on this representation, the PWS SI technique is extended to difference pattern calculation of radome enclosed antennas. The BSE of a three dimensional multilayered radome, with thickness tapers in all layers, is calculated through the difference pattern null searching. Owing to the steep slope of difference pattern near the nulls, this method for BSE calculation is more stable and reliable than the original beam maximum searching method in PWS SI analysis. The results are compared with those from aperture integration surface integration (AI SI) analysis and the measured ones.展开更多
稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope, DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分,工作在150–450 MHz频段,可提供高空间、高时间分辨率的太阳爆发亮温图像.针对DSRT天线的高精度指向测量以及对指向...稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope, DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分,工作在150–450 MHz频段,可提供高空间、高时间分辨率的太阳爆发亮温图像.针对DSRT天线的高精度指向测量以及对指向误差批量标定和校正的需求,首先根据DSRT独有的三轴座架系统,通过四元数旋转变换法建立了天线3参数编码器零点误差模型;然后提出了基于射电源的漂移扫描法获得16个单元天线功率方向图,并根据2维方向图确定波束中心的方法精确测量了DSRT天线指向误差;最后用最小二乘法拟合得到模型参数,并通过天线控制软件重新调整各个轴的零点,后对调整结果进行验证.结果表明指向校正方法可靠有效,校正后16个天线的指向精度为0.5°之内,明显优于校正前3.5°的指向误差,满足误差小于DSRT天线最高工作频率下的1/10波束范围内的要求.展开更多
为满足人机系统概率风险评估的需要,提出一种人为差错概率量化方法。分析技能、规则和知识为基础(skill,rule and knowledge-based,SRK)框架和行为模式的确定方法Hanaman决策树法,指出在确定行为模式的过程中考虑行为模式影响因素的不...为满足人机系统概率风险评估的需要,提出一种人为差错概率量化方法。分析技能、规则和知识为基础(skill,rule and knowledge-based,SRK)框架和行为模式的确定方法Hanaman决策树法,指出在确定行为模式的过程中考虑行为模式影响因素的不确定性是必要的;使用模糊逻辑方法处理行为模式各个影响因素的不确定性,根据Hanaman决策树构建模糊推理规则,利用系统人为行为可靠性程序(systematic human action reliability procedure,SHARP)方法所提供的人为差错概率区间确定人为差错概率的隶属度函数。结果表明:该方法考虑了任务场景的不确定性,可以得到人为差错概率的精确值,满足人机系统概率风险评估的需要。展开更多
基金the National Natural Science Foundation of China and the Military Science Foundation in Ministry of Electronic Industry of China.
文摘As the Welch-Berlekamp (W-B) theorem accurately predicts structure of error locator polynomials of the error patterns, it results in the Welch-Berlekamp algorithm of decoding cyclic codes. However, it is only valid within the BCH bound. Now, a prediction formula for error locator determination is presented based on the study of theory of minimal homogeneous interpolation problem, which extends the Welch-Berlekamp theorem and expands the Welch-Berlekamp algorithm so that the constraint from the BCH
基金Supported by the National Natural Science Foundation of China(6127117461272492)
文摘In this paper, we further study the connections between linear network error correction codes and representable matroids. We extend the concept of matroidal network introduced by Dougherty et al. to a generalized case when errors occur in multi- ple channels. Importantly, we show the necessary and sufficient conditions on the existence of linear network error correction mul- ticast/broadcast/dispersion maximum distance separable （MDS） code on a matroidal error correction network.
文摘By extending the notion of the minimum distance for linear network error correction code(LNEC), this paper introduces the concept of generalized minimum rank distance(GMRD) of variable-rate linear network error correction codes. The basic properties of GMRD are investigated. It is proved that GMRD can characterize the error correction/detection capability of variable-rate linear network error correction codes when the source transmits the messages at several different rates.
基金co-supported by the National Natural Science Foundation of China (Nos. 51475374 and 51505387)the Fundamental Research Funds for the Central Universities (No. 3102015ZY087)
文摘As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between the corresponding wax pattern and the internal ceramic core.However, due to locating errors, the actual position of ceramic core is always deviated from the ideal position, which makes it difficult to guarantee the wall-thickness precision of the wax pattern.To solve this problem, a wall-thickness compensation strategy is proposed in this paper. Firstly,based on the industrial computed tomography(ICT) technique and curve matching algorithms, a model reconstruction method is developed, with which the 3D model of a trial wax pattern can be easily constructed. After that, focusing on eliminating the wall-thickness errors of the trial wax pattern, an optimization method for the pose of the ceramic core in the wax pattern is proposed. Then, by mapping the optimal pose of the ceramic core to length adjustments of the locating rods, the wall-thickness errors of the wax pattern can be greatly reduced. A case study is also given to illustrate the effectiveness of the proposed compensation strategy.
文摘The plane wave spectrum surface integration (PWS SI) is a practical and efficient method for antenna radome system analysis, especially for determining the boresight error (BSE) in the system. But it is only used for sum pattern calculation till now, and BSE is calculated by the beam maximum searching method. In this paper, the aperture distribution for difference pattern is formulated as the product of that for sum pattern and a two dimensional periodic window function. A series representation for the spectrum of difference pattern is then obtained according to the convolution theorem. The truncation error of the series has been analyzed by introducing the coverage radius of the spectrum of sum pattern. Based on this representation, the PWS SI technique is extended to difference pattern calculation of radome enclosed antennas. The BSE of a three dimensional multilayered radome, with thickness tapers in all layers, is calculated through the difference pattern null searching. Owing to the steep slope of difference pattern near the nulls, this method for BSE calculation is more stable and reliable than the original beam maximum searching method in PWS SI analysis. The results are compared with those from aperture integration surface integration (AI SI) analysis and the measured ones.
文摘稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope, DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分,工作在150–450 MHz频段,可提供高空间、高时间分辨率的太阳爆发亮温图像.针对DSRT天线的高精度指向测量以及对指向误差批量标定和校正的需求,首先根据DSRT独有的三轴座架系统,通过四元数旋转变换法建立了天线3参数编码器零点误差模型;然后提出了基于射电源的漂移扫描法获得16个单元天线功率方向图,并根据2维方向图确定波束中心的方法精确测量了DSRT天线指向误差;最后用最小二乘法拟合得到模型参数,并通过天线控制软件重新调整各个轴的零点,后对调整结果进行验证.结果表明指向校正方法可靠有效,校正后16个天线的指向精度为0.5°之内,明显优于校正前3.5°的指向误差,满足误差小于DSRT天线最高工作频率下的1/10波束范围内的要求.
文摘为满足人机系统概率风险评估的需要,提出一种人为差错概率量化方法。分析技能、规则和知识为基础(skill,rule and knowledge-based,SRK)框架和行为模式的确定方法Hanaman决策树法,指出在确定行为模式的过程中考虑行为模式影响因素的不确定性是必要的;使用模糊逻辑方法处理行为模式各个影响因素的不确定性,根据Hanaman决策树构建模糊推理规则,利用系统人为行为可靠性程序(systematic human action reliability procedure,SHARP)方法所提供的人为差错概率区间确定人为差错概率的隶属度函数。结果表明:该方法考虑了任务场景的不确定性,可以得到人为差错概率的精确值,满足人机系统概率风险评估的需要。
