The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based ...The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based on the encoding structure,three theorems are proved,two related to the relationship between the length and rate of the polar code,and one related to the relationship between frozen-bit positions,information-bit positions,and codewords.With these three theorems,polar codes can be quickly reconstruced.In addition,to detect the dual vectors of codewords,the statistical characteristics of the log-likelihood ratio are analyzed,and then the information-and frozen-bit positions are distinguished based on the minimumerror decision criterion.The bit rate is obtained.The correctness of the theorems and effectiveness of the proposed algorithm are validated through simulations.The proposed algorithm exhibits robustness to noise and a reasonable computational complexity.展开更多
The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the...The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.展开更多
正交时频空(orthogonal time frequency space,OTFS)调制在高多普勒环境下可实现可靠通信,适用于卫星通信等高动态场景。然而,其峰值与平均功率比(peak-to-average power ratio,PAPR)易超出功放线性范围,导致非线性失真。部分传输序列(p...正交时频空(orthogonal time frequency space,OTFS)调制在高多普勒环境下可实现可靠通信,适用于卫星通信等高动态场景。然而,其峰值与平均功率比(peak-to-average power ratio,PAPR)易超出功放线性范围,导致非线性失真。部分传输序列(partial transfer sequence,PTS)算法通过对数据符号分块再选取合适的旋转因子可以抑制PAPR。为提高PTS算法抑制PAPR的能力,提出了一种基于改进的灰狼优化(improved grey wolf optimizer,IGWO)算法的PTS算法,即IGWO-PTS算法,以适应离散组合优化问题并获得更优的子块划分方案,从而获得更好的PAPR抑制能力。推导证明了当相位旋转因子集合元素具有旋转对称性时,相位旋转因子组合空间可以收缩为原来的1 K(K为集合中元素个数),极大程度上降低了系统复杂度。仿真实验表明,IGWO-PTS算法相对于传统算法具有更好的PAPR抑制性能,并且在星地高动态场景下可以保持良好的传输可靠性。展开更多
基金supported by the National Natural Science Foundation of China(62371465)Taishan Scholar Project of Shandong Province(ts201511020)the Chinese National Key Laboratory of Science and Technology on Information System Security(6142111190404).
文摘The syndrome a posteriori probability of the log-likelihood ratio of intercepted codewords is used to develop an algorithm that recognizes the polar code length and generator matrix of the underlying polar code.Based on the encoding structure,three theorems are proved,two related to the relationship between the length and rate of the polar code,and one related to the relationship between frozen-bit positions,information-bit positions,and codewords.With these three theorems,polar codes can be quickly reconstruced.In addition,to detect the dual vectors of codewords,the statistical characteristics of the log-likelihood ratio are analyzed,and then the information-and frozen-bit positions are distinguished based on the minimumerror decision criterion.The bit rate is obtained.The correctness of the theorems and effectiveness of the proposed algorithm are validated through simulations.The proposed algorithm exhibits robustness to noise and a reasonable computational complexity.
基金Project(2023YFC2907403)supported by the National Key R&D Program of ChinaProject(52074021)supported by the National Natural Science Foundation of China+1 种基金Project(2242045)supported by Beijing Natural Science Foundation,ChinaProject(ZD202216)supported by the Beijing Association of Higher Education,China。
文摘The macroscopic mechanical properties of rocks are significantly influenced by their microstructure.As a material bonded by mineral grains,the grain morphology of crystalline rock is the primary factor influencing the strength.However,most strength criteria neglect the strength variations caused by different grain characteristics in rocks.Furthermore,the traditional linear criteria tend to overestimate tensile strength and exhibit apex singularity.To address these shortcomings,a piecewise strength criterion that considers the grain size effect has been proposed.A part of an ellipse was employed to construct the envelope of the tensive-shear region on the meridian plane,to accurately reproduce the low tensile-compressive strength ratio.Based on the analysis of experimental data,both linear and exponential modification functions that account for grain size effects were integrated into the proposed criterion.The corresponding finite element algorithm has been implemented.The accuracy and applicability of the proposed criterion were validated by comparing with the experimental data.
文摘正交时频空(orthogonal time frequency space,OTFS)调制在高多普勒环境下可实现可靠通信,适用于卫星通信等高动态场景。然而,其峰值与平均功率比(peak-to-average power ratio,PAPR)易超出功放线性范围,导致非线性失真。部分传输序列(partial transfer sequence,PTS)算法通过对数据符号分块再选取合适的旋转因子可以抑制PAPR。为提高PTS算法抑制PAPR的能力,提出了一种基于改进的灰狼优化(improved grey wolf optimizer,IGWO)算法的PTS算法,即IGWO-PTS算法,以适应离散组合优化问题并获得更优的子块划分方案,从而获得更好的PAPR抑制能力。推导证明了当相位旋转因子集合元素具有旋转对称性时,相位旋转因子组合空间可以收缩为原来的1 K(K为集合中元素个数),极大程度上降低了系统复杂度。仿真实验表明,IGWO-PTS算法相对于传统算法具有更好的PAPR抑制性能,并且在星地高动态场景下可以保持良好的传输可靠性。
