首先,简要介绍了国内外卫星导航抗干扰研究现状,结合BLMS(Block Least MeanSquare)算法在GNSS抗干扰方面的应用,给出了其硬件实现的方框图和信号流程图,并对实现中存在的问题进行了分析;其次给出了一种实验室条件下模拟干扰环境,进行抗...首先,简要介绍了国内外卫星导航抗干扰研究现状,结合BLMS(Block Least MeanSquare)算法在GNSS抗干扰方面的应用,给出了其硬件实现的方框图和信号流程图,并对实现中存在的问题进行了分析;其次给出了一种实验室条件下模拟干扰环境,进行抗干扰算法研究的方法,即用信号发生器模拟干扰源和卫星信号,使其通过由功分器和合路器搭建的模拟阵列信号单元模拟干扰环境;最后,用单频干扰和扫频宽带干扰测试算法的抗干扰性能,并用Matlab编写的基带处理程序对算法的输出进行码相关,测量输出信号信干噪比(SINR)变化,以检验其有效性。数据表明,该算法具有良好的抑制干扰能力,为GNSS抗干扰研究提供了参考。展开更多
Various Wireless Sensor Network(WSN)applications require the common task of collecting the data from the sensor nodes using the sink.Since the procedure of collecting data is iterative,an effective technique is necess...Various Wireless Sensor Network(WSN)applications require the common task of collecting the data from the sensor nodes using the sink.Since the procedure of collecting data is iterative,an effective technique is necessary to obtain the data efficiently by reducing the consumption of nodal energy.Hence,a technique for data reduction in WSN is presented in this paper by proposing a prediction algorithm,called Hierarchical Fractional Bidirectional Least-Mean Square(HFBLMS)algorithm.The novel algorithm is designed by modifying Hierarchical Least-Mean Square(HLMS)algorithm with the inclusion of BLMS for bidirectional-based data prediction and Fractional Calculus(FC)in the weight update process.Data redundancy is achieved by transmitting only those data required based on the data predicted at the sensor node and the sink.Moreover,the proposed HFBLMS algorithm reduces the energy consumption in the network by the effective prediction attained by BLMS.Two metrics,such as energy consumption and prediction error,are used for the evaluation of performance of the HFBLMS prediction algorithm,where it can attain energy values of 0.3587 and 0.1953 at the maximum number of rounds and prediction errors of just 0.0213 and 0.0095,using air quality and localization datasets,respectively.展开更多
为探明Ca2+浓度增加是否会使鱼类早期发育阶段对铅毒性的敏感性升高,以及Ca2+单独减弱铅毒性的浓度范围,选用斑马鱼胚胎作为实验材料,记录在不同的水化学参数条件下,胚胎发育过程中一些具有代表性的毒理学终点,采用相对易于观察且敏感...为探明Ca2+浓度增加是否会使鱼类早期发育阶段对铅毒性的敏感性升高,以及Ca2+单独减弱铅毒性的浓度范围,选用斑马鱼胚胎作为实验材料,记录在不同的水化学参数条件下,胚胎发育过程中一些具有代表性的毒理学终点,采用相对易于观察且敏感的指标——72 h孵化率进行分析.用Visual MINTEQ2.5.2软件进行溶液中离子的化学形态分析.结果表明,当Ca2+浓度从0.25 mmol/L增加到2.00 mmol/L时,导致了以自由铅离子活度({Pb2+})和溶解态铅总浓度([Pb]T)表示的72 h EC50的增加(表现为发育延迟),两者之间存在良好的线性关系.通过这一线性关系,可以对Ca2+浓度对铅毒性的影响进行预测.这一结果支持了生物配体模型(BLM)概念的假设,说明在胚胎的表面,铅离子与钙离子可能在传输和毒性作用位点上存在竞争作用.而当Ca2+浓度从2.00 mmol/L增加到4.00 mmol/L时,72 h EC50{Pb2+}和72 h EC50[Pb]T并没有显著的增加.展开更多
文摘首先,简要介绍了国内外卫星导航抗干扰研究现状,结合BLMS(Block Least MeanSquare)算法在GNSS抗干扰方面的应用,给出了其硬件实现的方框图和信号流程图,并对实现中存在的问题进行了分析;其次给出了一种实验室条件下模拟干扰环境,进行抗干扰算法研究的方法,即用信号发生器模拟干扰源和卫星信号,使其通过由功分器和合路器搭建的模拟阵列信号单元模拟干扰环境;最后,用单频干扰和扫频宽带干扰测试算法的抗干扰性能,并用Matlab编写的基带处理程序对算法的输出进行码相关,测量输出信号信干噪比(SINR)变化,以检验其有效性。数据表明,该算法具有良好的抑制干扰能力,为GNSS抗干扰研究提供了参考。
文摘Various Wireless Sensor Network(WSN)applications require the common task of collecting the data from the sensor nodes using the sink.Since the procedure of collecting data is iterative,an effective technique is necessary to obtain the data efficiently by reducing the consumption of nodal energy.Hence,a technique for data reduction in WSN is presented in this paper by proposing a prediction algorithm,called Hierarchical Fractional Bidirectional Least-Mean Square(HFBLMS)algorithm.The novel algorithm is designed by modifying Hierarchical Least-Mean Square(HLMS)algorithm with the inclusion of BLMS for bidirectional-based data prediction and Fractional Calculus(FC)in the weight update process.Data redundancy is achieved by transmitting only those data required based on the data predicted at the sensor node and the sink.Moreover,the proposed HFBLMS algorithm reduces the energy consumption in the network by the effective prediction attained by BLMS.Two metrics,such as energy consumption and prediction error,are used for the evaluation of performance of the HFBLMS prediction algorithm,where it can attain energy values of 0.3587 and 0.1953 at the maximum number of rounds and prediction errors of just 0.0213 and 0.0095,using air quality and localization datasets,respectively.
文摘为探明Ca2+浓度增加是否会使鱼类早期发育阶段对铅毒性的敏感性升高,以及Ca2+单独减弱铅毒性的浓度范围,选用斑马鱼胚胎作为实验材料,记录在不同的水化学参数条件下,胚胎发育过程中一些具有代表性的毒理学终点,采用相对易于观察且敏感的指标——72 h孵化率进行分析.用Visual MINTEQ2.5.2软件进行溶液中离子的化学形态分析.结果表明,当Ca2+浓度从0.25 mmol/L增加到2.00 mmol/L时,导致了以自由铅离子活度({Pb2+})和溶解态铅总浓度([Pb]T)表示的72 h EC50的增加(表现为发育延迟),两者之间存在良好的线性关系.通过这一线性关系,可以对Ca2+浓度对铅毒性的影响进行预测.这一结果支持了生物配体模型(BLM)概念的假设,说明在胚胎的表面,铅离子与钙离子可能在传输和毒性作用位点上存在竞争作用.而当Ca2+浓度从2.00 mmol/L增加到4.00 mmol/L时,72 h EC50{Pb2+}和72 h EC50[Pb]T并没有显著的增加.
