Track-Before-Detect(TBD) is an efficient method to detect dim targets for radars. Conventional TBD usually follows an approximate motion model of the target, which may cause an inaccurate integration of the target ene...Track-Before-Detect(TBD) is an efficient method to detect dim targets for radars. Conventional TBD usually follows an approximate motion model of the target, which may cause an inaccurate integration of the target energy. A TBD technique on basis of pseudo-spectrum in mixed coordinates adopting an accurate motion model for bistatic radar system is developed in this paper.The predicted position in bistatic polar plane is derived according to a nonlinear function that exactly describes the constant Cartesian velocity motion. Then around the predicted position, a pseudo-spectrum is formulated and its samples are accumulated to the integration frame for energy integration. The evolution of the state and the procedure of accumulation of the target energy are derived elaborately. The superior performance of the proposed method is demonstrated by some simulations.展开更多
Propagation of stationary random waves in viscoelastic stratified transverse isotropic materials is investigated. The solid was considered multi-layered and located above the bedrock, which was assumed to be much stif...Propagation of stationary random waves in viscoelastic stratified transverse isotropic materials is investigated. The solid was considered multi-layered and located above the bedrock, which was assumed to be much stiffer than the soil, and the power spectrum density of the stationary random excitation was given at the bedrock. The governing differential equations are derived in frequency and wave-number domains and only a set of ordinary differential equations ( ODEs) must be solved. The precise integration algorithm of two-point boundary value problem was applied to solve the ODEs. Thereafter, the recently developed pseudo-excitation method for structural random vibration is extended to the solution of the stratified solid responses.展开更多
针对现有浅地层电磁探测设备受现场各种大型用电设备干扰强,导致信号失真严重,系统整体零件分散导致稳定性及使用维护不便,且体积较大不利于运输携带等问题,采用了一种智能功率管理模块(Intelligent Power Module,IPM)的电源功率组和抗...针对现有浅地层电磁探测设备受现场各种大型用电设备干扰强,导致信号失真严重,系统整体零件分散导致稳定性及使用维护不便,且体积较大不利于运输携带等问题,采用了一种智能功率管理模块(Intelligent Power Module,IPM)的电源功率组和抗噪性能优越的人工编码源伪随机码相结合设计的伪随机电磁发射机系统进行优化。文中从伪随机恒流方波脉冲电磁发射系统的原理、系统整体结构设计、硬件软件组成、样机实物形体描述以及实验结果方面进行了介绍,设计完成后整体体积较现有设备缩减了30%以上,经室外实验验证设计的发射机在抗噪性、稳定性、整装集成度以及后续维保便捷性方面都有较大程度的改善。展开更多
Since carbon nanotubes（CNTs） possess unique one dimensional（1D） structure, considerable attention has been paid to constructing CNTs into macroscopic materials with different dimensions, including 1D fibers,2D fil...Since carbon nanotubes（CNTs） possess unique one dimensional（1D） structure, considerable attention has been paid to constructing CNTs into macroscopic materials with different dimensions, including 1D fibers,2D films, and 3D foams. Such macroscopic CNT materials exhibit high conductivity, large surface area, as well as good mechanical properties, and thus can be directly used as the flexible supercapacitor（SC） electrodes or the scaffolds for supporting pseudo-capacitive electrode materials. Based on these macroscopic CNT electrodes, diverse SCs with different structures, including flexible, stretchable and/or compressible fiber and thin film SCs, have been designed. This review provides an overview of recent progress towards the development of flexible SCs based on macroscopic CNTs-based electrodes, with a focus on electrode preparation and configuration design as well as their integration with other multifunctional devices.Future development and prospects in the CNTs-based flexible SCs are also discussed.展开更多
以2000—2019年CNKI和Web of Science为数据源,运用CiteSpace的文献计量、可视化分析与内容分析对国内外人居环境研究进行探究与展望。研究表明:①主题演化上,国内外人居环境研究呈现出波动增长伴随阶段式跨越的特点,研究主题起源于城...以2000—2019年CNKI和Web of Science为数据源,运用CiteSpace的文献计量、可视化分析与内容分析对国内外人居环境研究进行探究与展望。研究表明:①主题演化上,国内外人居环境研究呈现出波动增长伴随阶段式跨越的特点,研究主题起源于城市问题并逐步扩展到政策制定、城市规划等层面,学科主题从最初的规划学趋向于多元化学科发展,交叉学科的融合已成为该主题发展的重要特征;②研究热点上,国外人居环境研究热点多涉及环境、城市、气候变化等领域,国内多集中在人居环境、城市与农村、城市化等方面,可持续发展为国内外人居环境研究的共有属性;③数据方法上,多元化新数据、集成化新方法赋予新时代人居环境研究更多可能性;④研究动向上,有望在地理大数据、遥感影像数据以及“大+小数据”等多源数据的基础之上,将计量地理学、地理信息科学以及其他新兴学科的研究方法有机整合,深度学习与研究拟态人居环境、人居主体行为以及美丽人居环境。展开更多
基金supported in part by the National Natural Science Foundation of China (No. 61671181)the Heilongjiang Outstanding Youth Science Fund,China (No.JQ2022F002)。
文摘Track-Before-Detect(TBD) is an efficient method to detect dim targets for radars. Conventional TBD usually follows an approximate motion model of the target, which may cause an inaccurate integration of the target energy. A TBD technique on basis of pseudo-spectrum in mixed coordinates adopting an accurate motion model for bistatic radar system is developed in this paper.The predicted position in bistatic polar plane is derived according to a nonlinear function that exactly describes the constant Cartesian velocity motion. Then around the predicted position, a pseudo-spectrum is formulated and its samples are accumulated to the integration frame for energy integration. The evolution of the state and the procedure of accumulation of the target energy are derived elaborately. The superior performance of the proposed method is demonstrated by some simulations.
基金Project supported by the National Natural Science Foundation of China (No. 10472023)the Special Fund for PhD Program of Education Ministry of China (No. 20040141020)
文摘Propagation of stationary random waves in viscoelastic stratified transverse isotropic materials is investigated. The solid was considered multi-layered and located above the bedrock, which was assumed to be much stiffer than the soil, and the power spectrum density of the stationary random excitation was given at the bedrock. The governing differential equations are derived in frequency and wave-number domains and only a set of ordinary differential equations ( ODEs) must be solved. The precise integration algorithm of two-point boundary value problem was applied to solve the ODEs. Thereafter, the recently developed pseudo-excitation method for structural random vibration is extended to the solution of the stratified solid responses.
文摘针对现有浅地层电磁探测设备受现场各种大型用电设备干扰强,导致信号失真严重,系统整体零件分散导致稳定性及使用维护不便,且体积较大不利于运输携带等问题,采用了一种智能功率管理模块(Intelligent Power Module,IPM)的电源功率组和抗噪性能优越的人工编码源伪随机码相结合设计的伪随机电磁发射机系统进行优化。文中从伪随机恒流方波脉冲电磁发射系统的原理、系统整体结构设计、硬件软件组成、样机实物形体描述以及实验结果方面进行了介绍,设计完成后整体体积较现有设备缩减了30%以上,经室外实验验证设计的发射机在抗噪性、稳定性、整装集成度以及后续维保便捷性方面都有较大程度的改善。
基金supported by the MOST (Ministry of Science and Technology of China) (No. 2017YFA0206701)NSFC (National Natural Science Foundation of China) (Nos. 51602218, 21573116, 11604242)+1 种基金MOE (Ministry of Education of China) (No. B12015)Tianjin Basic and High-Tech Development (No. 15JCYBJC17300)
文摘Since carbon nanotubes（CNTs） possess unique one dimensional（1D） structure, considerable attention has been paid to constructing CNTs into macroscopic materials with different dimensions, including 1D fibers,2D films, and 3D foams. Such macroscopic CNT materials exhibit high conductivity, large surface area, as well as good mechanical properties, and thus can be directly used as the flexible supercapacitor（SC） electrodes or the scaffolds for supporting pseudo-capacitive electrode materials. Based on these macroscopic CNT electrodes, diverse SCs with different structures, including flexible, stretchable and/or compressible fiber and thin film SCs, have been designed. This review provides an overview of recent progress towards the development of flexible SCs based on macroscopic CNTs-based electrodes, with a focus on electrode preparation and configuration design as well as their integration with other multifunctional devices.Future development and prospects in the CNTs-based flexible SCs are also discussed.
文摘以2000—2019年CNKI和Web of Science为数据源,运用CiteSpace的文献计量、可视化分析与内容分析对国内外人居环境研究进行探究与展望。研究表明:①主题演化上,国内外人居环境研究呈现出波动增长伴随阶段式跨越的特点,研究主题起源于城市问题并逐步扩展到政策制定、城市规划等层面,学科主题从最初的规划学趋向于多元化学科发展,交叉学科的融合已成为该主题发展的重要特征;②研究热点上,国外人居环境研究热点多涉及环境、城市、气候变化等领域,国内多集中在人居环境、城市与农村、城市化等方面,可持续发展为国内外人居环境研究的共有属性;③数据方法上,多元化新数据、集成化新方法赋予新时代人居环境研究更多可能性;④研究动向上,有望在地理大数据、遥感影像数据以及“大+小数据”等多源数据的基础之上,将计量地理学、地理信息科学以及其他新兴学科的研究方法有机整合,深度学习与研究拟态人居环境、人居主体行为以及美丽人居环境。
