A new high dynamic synchronization algorithm using cyclic spectral density was presented according to the theories of cyclic spectral density and its anti-interface and anti-noise properties.The closed forms of freque...A new high dynamic synchronization algorithm using cyclic spectral density was presented according to the theories of cyclic spectral density and its anti-interface and anti-noise properties.The closed forms of frequency error and phase error were obtained,and their performances were analyzed.The in-phase signal throw costas loop was normalized to obtain a cosine signal.Cyclic spectral density of the cosine signal of was computed to obtain the frequency error and the phase error and then results were put into NCO to synchronize.Finally,the performance of the presented algorithms was compared with the conventional algorithms by virtue of simulations,and the simulation results proved the correctness and the superiority of the new algorithms.展开更多
A k-cyclic graph is a connected graph of order n and size n + k-1. In this paper, we determine the maximal signless Laplacian spectral radius and the corresponding extremal graph among all C_4-free k-cyclic graphs of ...A k-cyclic graph is a connected graph of order n and size n + k-1. In this paper, we determine the maximal signless Laplacian spectral radius and the corresponding extremal graph among all C_4-free k-cyclic graphs of order n. Furthermore, we determine the first three unicycles and bicyclic, C_4-free graphs whose spectral radius of the signless Laplacian is maximal. Similar results are obtained for the(combinatorial)展开更多
A new five-heterocyclic-biphosphine-substituted Fe-only hydrogenase mimic,[（μ-pdt）Fe_2（CO）_5]_2（PTP）（1）,has been synthesized at room temperature. 1·H_2O crystallizes in triclinic system,space group P1,wi...A new five-heterocyclic-biphosphine-substituted Fe-only hydrogenase mimic,[（μ-pdt）Fe_2（CO）_5]_2（PTP）（1）,has been synthesized at room temperature. 1·H_2O crystallizes in triclinic system,space group P1,with a = 11.5897（4）,b = 13.6156（4）,c = 18.0333（6） ？,α = 76.306（3）,β = 72.742（3）,γ = 68.939（3）°,V = 2508.84（14） ？~3,Dc = 1.570 g/cm3,Z = 2,M_r = 1186.37,F（000） = 1204,the final R = 0.0748,and wR = 0.2012. In the tetranuclear complex 1·H_2O,each [2Fe_2S] butterfly unit is attached to one P atom of the diphosphine bridge and exhibits a square-pyramidal geometry. Complex 1 was characterized by elemental analysis,IR spectra,UV-vis absorption spectra,~1H-NMR and ^（31）P-NMR. The cyclic voltammetry behavior of compound 1 was investigated as well.展开更多
Second-order almost cycloststionary complex processes are complex random signals with almost periodically time-varying statistics. Smoothed periodograms are proposed for related to cyclic spectral estimation and are s...Second-order almost cycloststionary complex processes are complex random signals with almost periodically time-varying statistics. Smoothed periodograms are proposed for related to cyclic spectral estimation and are shown to be consistent. Asymptotic covariance expressions are derived along with their computable forms.展开更多
为了应对复杂环境下非合作通信、电磁频谱监管等宽带接收中存在的先验信息缺失,针对单通道混合信号的参数盲估计问题,提出了一种基于比特谱相关算法改进循环谱估计的快速算法。针对信号集{BPSK、QPSK、OQPSK、8PSK、8QAM、16QAM、16APSK...为了应对复杂环境下非合作通信、电磁频谱监管等宽带接收中存在的先验信息缺失,针对单通道混合信号的参数盲估计问题,提出了一种基于比特谱相关算法改进循环谱估计的快速算法。针对信号集{BPSK、QPSK、OQPSK、8PSK、8QAM、16QAM、16APSK、32APSK、CPM},系统给出整套参数估计算法流程,通过高阶累积量以及功率中心方法确定信号个数以及载波频率,然后利用改进循环谱提取符号速率谱线,完成单通道混合信号参数估计。论文对改进算法的统计特性进行了理论推导。理论和实验表明:算法不需要同步码等先验信息,适用于高斯噪声信道和多径平坦衰落信道,同时降低了计算复杂度、存储空间、估计方差以及数据量的需求,当混合信号等功率混合时,且信噪比分别为-4 d B和-1 d B时,算法对载波频率和符号速率的估计正确率可以达到90%,验证了算法的有效性和可行性。展开更多
基金Sponsored by the National Basic Research Program (Grant No. 2007CB310601)the High Technology Research and Development Program of China(Grant No. 2007AA12Z338)
文摘A new high dynamic synchronization algorithm using cyclic spectral density was presented according to the theories of cyclic spectral density and its anti-interface and anti-noise properties.The closed forms of frequency error and phase error were obtained,and their performances were analyzed.The in-phase signal throw costas loop was normalized to obtain a cosine signal.Cyclic spectral density of the cosine signal of was computed to obtain the frequency error and the phase error and then results were put into NCO to synchronize.Finally,the performance of the presented algorithms was compared with the conventional algorithms by virtue of simulations,and the simulation results proved the correctness and the superiority of the new algorithms.
基金Supported by the National Natural Science Foundation of China（11171273） Supported by the Seed Foundation of Innovation and Creation for Graduate Students in Northwestern Polytechnical Uni- versity（Z2016170）
文摘A k-cyclic graph is a connected graph of order n and size n + k-1. In this paper, we determine the maximal signless Laplacian spectral radius and the corresponding extremal graph among all C_4-free k-cyclic graphs of order n. Furthermore, we determine the first three unicycles and bicyclic, C_4-free graphs whose spectral radius of the signless Laplacian is maximal. Similar results are obtained for the(combinatorial)
基金supported by the NNSFC(Nos.21231003 and 21203195)
文摘A new five-heterocyclic-biphosphine-substituted Fe-only hydrogenase mimic,[（μ-pdt）Fe_2（CO）_5]_2（PTP）（1）,has been synthesized at room temperature. 1·H_2O crystallizes in triclinic system,space group P1,with a = 11.5897（4）,b = 13.6156（4）,c = 18.0333（6） ？,α = 76.306（3）,β = 72.742（3）,γ = 68.939（3）°,V = 2508.84（14） ？~3,Dc = 1.570 g/cm3,Z = 2,M_r = 1186.37,F（000） = 1204,the final R = 0.0748,and wR = 0.2012. In the tetranuclear complex 1·H_2O,each [2Fe_2S] butterfly unit is attached to one P atom of the diphosphine bridge and exhibits a square-pyramidal geometry. Complex 1 was characterized by elemental analysis,IR spectra,UV-vis absorption spectra,~1H-NMR and ^（31）P-NMR. The cyclic voltammetry behavior of compound 1 was investigated as well.
文摘Second-order almost cycloststionary complex processes are complex random signals with almost periodically time-varying statistics. Smoothed periodograms are proposed for related to cyclic spectral estimation and are shown to be consistent. Asymptotic covariance expressions are derived along with their computable forms.
文摘为了应对复杂环境下非合作通信、电磁频谱监管等宽带接收中存在的先验信息缺失,针对单通道混合信号的参数盲估计问题,提出了一种基于比特谱相关算法改进循环谱估计的快速算法。针对信号集{BPSK、QPSK、OQPSK、8PSK、8QAM、16QAM、16APSK、32APSK、CPM},系统给出整套参数估计算法流程,通过高阶累积量以及功率中心方法确定信号个数以及载波频率,然后利用改进循环谱提取符号速率谱线,完成单通道混合信号参数估计。论文对改进算法的统计特性进行了理论推导。理论和实验表明:算法不需要同步码等先验信息,适用于高斯噪声信道和多径平坦衰落信道,同时降低了计算复杂度、存储空间、估计方差以及数据量的需求,当混合信号等功率混合时,且信噪比分别为-4 d B和-1 d B时,算法对载波频率和符号速率的估计正确率可以达到90%,验证了算法的有效性和可行性。
