To solve the problem of the large Doppler frequency offset in the LEO communication system, this paper studies a rapid PN code acquisition method based on the PMF-FFT architecture, which searches the phase and frequen...To solve the problem of the large Doppler frequency offset in the LEO communication system, this paper studies a rapid PN code acquisition method based on the PMF-FFT architecture, which searches the phase and frequency offset and at the same time reduces the acquisition time. It presents an improved method equivalent to windowing function and uses windowing process to overcome the attenuation of related peak envelope caused by partial matched filters.展开更多
Background: The conventional HIV testing algorithm in most of the developed countries consists of two tests: an HIV enzyme immunoassay capable of identifying HIV-1 and HIV-2 antibodies and a confirmatory HIV-1 Western...Background: The conventional HIV testing algorithm in most of the developed countries consists of two tests: an HIV enzyme immunoassay capable of identifying HIV-1 and HIV-2 antibodies and a confirmatory HIV-1 Western blot or immunofluorescence assay. However, the current algorithm for HIV diagnosis in India uses three sequential antibody assays. There has always been doubt regarding the benefits of this algorithm. Objective: To determine the utility of the current diagnostic algorithm and to find out the proportion of indeterminate or discrepant results. Methods: Retrospective analysis of HIV antibody testing data was carried out over a period of five years after institutional ethics committee approval. The specimens positive with the screening test and negative with both the supplemental tests were labeled as discrepant. Specimens positive with any of the two tests (screening and one of the supplemental tests) and negative with the remaining supplemental test were labeled as indeterminate. These indeterminate specimens were confirmed by immunoblotting. Results: A total of 141,296 samples were tested. Of these, 71 (0.05%) samples were indeterminate and 292 (0.21%) were discrepant. Western blot was done on 60 indeterminate samples of which 10 (16.67%) were positive for HIV 1 antibodies, 14 (23.33%) were negative for HIV antibodies and 36 (60%) had indeterminate result. Conclusion: In view of the low numbers of indeterminate and discrepant results, the current algorithm appears to be appropriate in our resource constrained setting. However, the algorithm for HIV testing should also include DNA PCR testing facility to resolve western blot indeterminate results.展开更多
Rapid solidifiation is a kind of new process for enhancing the hardness and electrical conductivity of Cu-Cr-Zr copper alloy.The use of BP neural network(NN) is presented to model the non-linear relationship between p...Rapid solidifiation is a kind of new process for enhancing the hardness and electrical conductivity of Cu-Cr-Zr copper alloy.The use of BP neural network(NN) is presented to model the non-linear relationship between parameters of age hardening processes and the mechanical and electrical properties of rapdily solidified Cu-Cr-Zr alloy.The improved model is developed by the Levenberg-Marquardt training algorithm and the good generalization performance is demonstrated.So,an important foundation has been laid for optimisticaly controlling the rapidly solidified aging processes of Cu-Cr-Zr alloy.展开更多
针对快速搜索随机树(RRT)算法在航迹规划过程中存在采样点扩展随机性强、航迹曲折不平滑等问题,提出了一种基于约束随机采样点的RRT(Constrained Random Sampling-based RRT,CRS-RRT)算法。该算法引入人工势场法中的引力场势能函数约束...针对快速搜索随机树(RRT)算法在航迹规划过程中存在采样点扩展随机性强、航迹曲折不平滑等问题,提出了一种基于约束随机采样点的RRT(Constrained Random Sampling-based RRT,CRS-RRT)算法。该算法引入人工势场法中的引力场势能函数约束随机采样点在目标点附近采样,引导随机树朝着目标点生长,提高算法的规划速度,并结合去除冗余节点策略和Minimum Snap航迹平滑方法,在复杂三维环境中可快速生成一条安全、平滑且满足无人机动力学约束的航迹。仿真结果表明,该算法有效提高航迹规划速度并缩短航迹长度。展开更多
文摘To solve the problem of the large Doppler frequency offset in the LEO communication system, this paper studies a rapid PN code acquisition method based on the PMF-FFT architecture, which searches the phase and frequency offset and at the same time reduces the acquisition time. It presents an improved method equivalent to windowing function and uses windowing process to overcome the attenuation of related peak envelope caused by partial matched filters.
文摘Background: The conventional HIV testing algorithm in most of the developed countries consists of two tests: an HIV enzyme immunoassay capable of identifying HIV-1 and HIV-2 antibodies and a confirmatory HIV-1 Western blot or immunofluorescence assay. However, the current algorithm for HIV diagnosis in India uses three sequential antibody assays. There has always been doubt regarding the benefits of this algorithm. Objective: To determine the utility of the current diagnostic algorithm and to find out the proportion of indeterminate or discrepant results. Methods: Retrospective analysis of HIV antibody testing data was carried out over a period of five years after institutional ethics committee approval. The specimens positive with the screening test and negative with both the supplemental tests were labeled as discrepant. Specimens positive with any of the two tests (screening and one of the supplemental tests) and negative with the remaining supplemental test were labeled as indeterminate. These indeterminate specimens were confirmed by immunoblotting. Results: A total of 141,296 samples were tested. Of these, 71 (0.05%) samples were indeterminate and 292 (0.21%) were discrepant. Western blot was done on 60 indeterminate samples of which 10 (16.67%) were positive for HIV 1 antibodies, 14 (23.33%) were negative for HIV antibodies and 36 (60%) had indeterminate result. Conclusion: In view of the low numbers of indeterminate and discrepant results, the current algorithm appears to be appropriate in our resource constrained setting. However, the algorithm for HIV testing should also include DNA PCR testing facility to resolve western blot indeterminate results.
文摘Rapid solidifiation is a kind of new process for enhancing the hardness and electrical conductivity of Cu-Cr-Zr copper alloy.The use of BP neural network(NN) is presented to model the non-linear relationship between parameters of age hardening processes and the mechanical and electrical properties of rapdily solidified Cu-Cr-Zr alloy.The improved model is developed by the Levenberg-Marquardt training algorithm and the good generalization performance is demonstrated.So,an important foundation has been laid for optimisticaly controlling the rapidly solidified aging processes of Cu-Cr-Zr alloy.
文摘针对快速搜索随机树(RRT)算法在航迹规划过程中存在采样点扩展随机性强、航迹曲折不平滑等问题,提出了一种基于约束随机采样点的RRT(Constrained Random Sampling-based RRT,CRS-RRT)算法。该算法引入人工势场法中的引力场势能函数约束随机采样点在目标点附近采样,引导随机树朝着目标点生长,提高算法的规划速度,并结合去除冗余节点策略和Minimum Snap航迹平滑方法,在复杂三维环境中可快速生成一条安全、平滑且满足无人机动力学约束的航迹。仿真结果表明,该算法有效提高航迹规划速度并缩短航迹长度。
