By taking advantage of three different computational analytical methods:the Lie symmetry analysis,the generalized Riccati equation mapping approach,and the modified Kudryashov approach,we construct multiple new analyt...By taking advantage of three different computational analytical methods:the Lie symmetry analysis,the generalized Riccati equation mapping approach,and the modified Kudryashov approach,we construct multiple new analytical soliton solutions to the nonlinear convection-diffusion-reaction equation(NCDR)with power-law nonlinearity and density-dependent diffusion.Lie symmetry analysis is one of the pow-erful techniques that reduce the higher-order partial differential equation into an ordinary differential equation by reduction of independent variables.By the Lie group technique,we obtain one-parameter in-variant transformations,determining equations and corresponding vectors for the considered convection-diffusion-reaction equation.By treating the parameters of the governing equation as constants,the ap-plied methods yield a variety of new closed-form solutions,including inverse function solutions,periodic solutions,exponential function solutions,dark solitons,singular solitons,combo bright-singular solitons,and the combine of bright-dark solitons and dark-bright solitons.Moreover,using the Bäcklund transfor-mation of the generalized Riccati equation and modified Kudryashov method,we can construct multiple solitons and other solutions of the considered equation.The obtained new solutions of this work demon-strate that the used approaches are powerful and effective in dealing with nonlinear equations,and that these solutions are required to explain many biological and physical phenomena.Comparing our obtained solutions of this paper with the ones obtained in the literature,we see that our solutions are new and not reported elsewhere.These newly formed soliton solutions will be more beneficial in the various dis-ciplines of ocean engineering,plasma physics,and nonlinear sciences.展开更多
本文是关于动态域上不连续动力系统理论进展的一个综述.笔者给出了具边界转换的不连续动力系统和具时间切换的不连续动力系统的基本概念;提出了不连续动力系统的两个特征:其一是所考虑的不连续动力系统具有随时间变化的定义域.其二是所...本文是关于动态域上不连续动力系统理论进展的一个综述.笔者给出了具边界转换的不连续动力系统和具时间切换的不连续动力系统的基本概念;提出了不连续动力系统的两个特征:其一是所考虑的不连续动力系统具有随时间变化的定义域.其二是所考虑的不连续动力系统具有关于边界或切换时刻的不连续性.由此自然提出了关于动态域上不连续动力系统的动力学问题,包括流的奇异性规律、周期运动特性、转换分支性态及复杂动力学等.笔者着重介绍了近年逐渐形成的动态域上不连续动力系统理论(2005年由Luo A C J提出):首先纵览不连续动力系统研究所经历的三次发展浪潮,致力于展现该理论形成的历史过程;接着勾画出该理论的基本架构,即以不连续动力系统流转换理论和映射动力学为基本内容,并由其自然派生拓展出不连续动力系统转换分支理论、流障碍理论、多值向量场理论等.动态域上不连续动力系统理论的关键之处在于:受物理能量层启发,针对不连续动力系统动边界提出了“G函数”的核心概念.G函数实质上是借助极限工具在动边界任一点局部给出一种度量方法,从而使得精细研究动态边界上流的转换成为可能.本文还介绍了关于不连续动力系统研究的一些新进展.展开更多
With an extended mapping approach and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions, and rational function solutions) ...With an extended mapping approach and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions, and rational function solutions) with arbitrary functions for (3+1)-dimensionai Burgers system is derived. Based on the derived excitations, we obtain some novel localized coherent structures and study the interactions between solitons.展开更多
Eight sets of coastal acoustic tomography (CAT) systems were deployed during November 29 to December 10, 2002 at the coasts on both sides of Tokyo Bay to measure tidal current structures at 15-min interval.Sound trans...Eight sets of coastal acoustic tomography (CAT) systems were deployed during November 29 to December 10, 2002 at the coasts on both sides of Tokyo Bay to measure tidal current structures at 15-min interval.Sound transmission across the Tokyo Bay (between Yokohama and Chiba)was successfully traced,even under severe interference from ship generated wakes and bubbles.Tidal current fields changing from northward to southward flow are well reconstructed by the inverse analysis of travel-time difference data for a period with the best sound transmission condition. It is suggested that the CAT is the most powerful tool to continuously map tidal current fields in the coastal seas with heavy shipping traffic and fisheries activity.展开更多
为了降低二维MUSIC(Two Dimensional Multiple Signal Classification,2-D MUSIC)算法的计算量,提高算法的实时处理能力,基于噪声子空间映射思想提出了一种适用于任意平面阵列结构的二维波达角(Direction Of Arrival,DOA)快速估计算法....为了降低二维MUSIC(Two Dimensional Multiple Signal Classification,2-D MUSIC)算法的计算量,提高算法的实时处理能力,基于噪声子空间映射思想提出了一种适用于任意平面阵列结构的二维波达角(Direction Of Arrival,DOA)快速估计算法.新算法利用空间角度划分及非线性变换将信号子空间与噪声子空间的正交性等价地压缩至某个角度分片内,使得真实DOA在该角度分片内产生虚拟镜像,通过搜索该角度分片得到虚拟DOA,最后利用数学式直接计算得到真实DOA.理论分析和实验结果表明新算法能够成倍地提高DOA估计的速度,同时具有比MUSIC算法更高的空间分辨率.展开更多
Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends a...Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells.展开更多
文摘By taking advantage of three different computational analytical methods:the Lie symmetry analysis,the generalized Riccati equation mapping approach,and the modified Kudryashov approach,we construct multiple new analytical soliton solutions to the nonlinear convection-diffusion-reaction equation(NCDR)with power-law nonlinearity and density-dependent diffusion.Lie symmetry analysis is one of the pow-erful techniques that reduce the higher-order partial differential equation into an ordinary differential equation by reduction of independent variables.By the Lie group technique,we obtain one-parameter in-variant transformations,determining equations and corresponding vectors for the considered convection-diffusion-reaction equation.By treating the parameters of the governing equation as constants,the ap-plied methods yield a variety of new closed-form solutions,including inverse function solutions,periodic solutions,exponential function solutions,dark solitons,singular solitons,combo bright-singular solitons,and the combine of bright-dark solitons and dark-bright solitons.Moreover,using the Bäcklund transfor-mation of the generalized Riccati equation and modified Kudryashov method,we can construct multiple solitons and other solutions of the considered equation.The obtained new solutions of this work demon-strate that the used approaches are powerful and effective in dealing with nonlinear equations,and that these solutions are required to explain many biological and physical phenomena.Comparing our obtained solutions of this paper with the ones obtained in the literature,we see that our solutions are new and not reported elsewhere.These newly formed soliton solutions will be more beneficial in the various dis-ciplines of ocean engineering,plasma physics,and nonlinear sciences.
文摘本文是关于动态域上不连续动力系统理论进展的一个综述.笔者给出了具边界转换的不连续动力系统和具时间切换的不连续动力系统的基本概念;提出了不连续动力系统的两个特征:其一是所考虑的不连续动力系统具有随时间变化的定义域.其二是所考虑的不连续动力系统具有关于边界或切换时刻的不连续性.由此自然提出了关于动态域上不连续动力系统的动力学问题,包括流的奇异性规律、周期运动特性、转换分支性态及复杂动力学等.笔者着重介绍了近年逐渐形成的动态域上不连续动力系统理论(2005年由Luo A C J提出):首先纵览不连续动力系统研究所经历的三次发展浪潮,致力于展现该理论形成的历史过程;接着勾画出该理论的基本架构,即以不连续动力系统流转换理论和映射动力学为基本内容,并由其自然派生拓展出不连续动力系统转换分支理论、流障碍理论、多值向量场理论等.动态域上不连续动力系统理论的关键之处在于:受物理能量层启发,针对不连续动力系统动边界提出了“G函数”的核心概念.G函数实质上是借助极限工具在动边界任一点局部给出一种度量方法,从而使得精细研究动态边界上流的转换成为可能.本文还介绍了关于不连续动力系统研究的一些新进展.
基金The project supported by the Natural Science Foundation of Zhejiang Province under Grant Nos.Y606128 and Y604106the Natural Science Foundation of Zhejiang Lishui University under Grant Nos.FC06001 and QN06009
文摘With an extended mapping approach and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions, and rational function solutions) with arbitrary functions for (3+1)-dimensionai Burgers system is derived. Based on the derived excitations, we obtain some novel localized coherent structures and study the interactions between solitons.
文摘Eight sets of coastal acoustic tomography (CAT) systems were deployed during November 29 to December 10, 2002 at the coasts on both sides of Tokyo Bay to measure tidal current structures at 15-min interval.Sound transmission across the Tokyo Bay (between Yokohama and Chiba)was successfully traced,even under severe interference from ship generated wakes and bubbles.Tidal current fields changing from northward to southward flow are well reconstructed by the inverse analysis of travel-time difference data for a period with the best sound transmission condition. It is suggested that the CAT is the most powerful tool to continuously map tidal current fields in the coastal seas with heavy shipping traffic and fisheries activity.
文摘为了降低二维MUSIC(Two Dimensional Multiple Signal Classification,2-D MUSIC)算法的计算量,提高算法的实时处理能力,基于噪声子空间映射思想提出了一种适用于任意平面阵列结构的二维波达角(Direction Of Arrival,DOA)快速估计算法.新算法利用空间角度划分及非线性变换将信号子空间与噪声子空间的正交性等价地压缩至某个角度分片内,使得真实DOA在该角度分片内产生虚拟镜像,通过搜索该角度分片得到虚拟DOA,最后利用数学式直接计算得到真实DOA.理论分析和实验结果表明新算法能够成倍地提高DOA估计的速度,同时具有比MUSIC算法更高的空间分辨率.
基金supported by the National Natural Science Foundation of China,No.81471308(to JL)the Stem Cell Clinical Research Project in China,No.CMR-20161129-1003(to JL)the Innovation Technology Funding of Dalian in China,No.2018J11CY025(to JL)
文摘Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells.