Long-term seismic activity prior to the December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake was investigated using the Harvard CMT catalogue. It is observed that before this great e...Long-term seismic activity prior to the December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake was investigated using the Harvard CMT catalogue. It is observed that before this great earth-quake, there exists an accelerating moment release (AMR) process with the temporal scale of a quarter century and the spatial scale of 1 500 km. Within this spatial range, the MW=9.0 event falls into the piece-wise power-law-like frequency-magnitude distribution. Therefore, in the perspective of the critical-point-like model of earthquake preparation, the failure to forecast/predict the approaching and/or the size of this earthquake is not due to the physically intrinsic unpredictability of earthquakes.展开更多
当前,无线电引信面临严峻的信息型干扰环境,为保证无线电引信在战场上稳定发挥毁伤效能,抗信息型干扰相关技术成为无线电引信抗干扰领域的研究热点。根据引信干扰机先截获后转发干扰的工作流程,着眼于无线电引信的低截获波束设计,并结...当前,无线电引信面临严峻的信息型干扰环境,为保证无线电引信在战场上稳定发挥毁伤效能,抗信息型干扰相关技术成为无线电引信抗干扰领域的研究热点。根据引信干扰机先截获后转发干扰的工作流程,着眼于无线电引信的低截获波束设计,并结合频控阵(Frequency Diverse Array,FDA)-多输入多输出(Multiple-Input Multiple-Output,MIMO)技术独特的S形弯曲阵列方向图,探索基于FDA-MIMO的无线电引信低截获点状波束设计方法。在分析FDA-MIMO的波束函数后,聚焦于阵元频偏设置对波束合成的影响这一关键点。通过将波峰点与功率下降点设置在较近距离范围Δr内,实现在波峰点附近以Δr为半径的较小邻域内波束幅值较大,而在其他范围波束幅值快速下降的目标,进而运用波束函数解算出各阵元频偏,得到以阵元频偏设置公式为核心的低截获点状波束设计方法。仿真结果表明:在低截获点状波束设计方法的指导下,FDA-MIMO波束在距离维半功率波束宽度为1 m和角度维半功率波束宽度为9°,波束汇聚性能和低截获性能明显好于其他经典频偏设置方法;该设计方法为基于FDA-MIMO的无线电引信低截获波束设计提供了理论支撑,可以提高无线电引信的低截获性能,更好的发挥战场毁伤效能。展开更多
In this study, we focus into the non-relativistic wave equation described by the Schrodinger equation, specifically considering angular-dependent potentials within the context of a topological defect background genera...In this study, we focus into the non-relativistic wave equation described by the Schrodinger equation, specifically considering angular-dependent potentials within the context of a topological defect background generated by a cosmic string. Our primary goal is to explore quasi-exactly solvable problems by introducing an extended ring-shaped potential. We utilize the Bethe ansatz method to determine the angular solutions, while the radial solutions are obtained using special functions. Our findings demonstrate that the eigenvalue solutions of quantum particles are intricately influenced by the presence of the topological defect of the cosmic string,resulting in significant modifications compared to those in a flat space background. The existence of the topological defect induces alterations in the energy spectra, disrupting degeneracy.Afterwards, we extend our analysis to study the same problem in the presence of a ring-shaped potential against the background of another topological defect geometry known as a point-like global monopole. Following a similar procedure, we obtain the eigenvalue solutions and analyze the results. Remarkably, we observe that the presence of a global monopole leads to a decrease in the energy levels compared to the flat space results. In both cases, we conduct a thorough numerical analysis to validate our findings.展开更多
针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦...针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦合效应,对导引头典型状态的流场进行了模拟,获得了流场的密度、温度、压力等参数和窗口的温度场参数。基于流场参数,利用HyFLOW气动光学传输效应计算功能,开展了红外光学传输成像计算;利用HyFLOW气动光学辐射效应计算模块,开展了流场和光学窗口的热辐射计算。计算结果表明,类THAAD导引头在30 km以上飞行时,流场和光学窗口基本不会影响目标信号的光学传输成像,但流场和窗口的热辐射效应会对导引头识别目标造成影响。不过随着飞行高度的升高,这种影响会减小。展开更多
基金Ministry of Science and Technology Project (2004CB418406).
文摘Long-term seismic activity prior to the December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake was investigated using the Harvard CMT catalogue. It is observed that before this great earth-quake, there exists an accelerating moment release (AMR) process with the temporal scale of a quarter century and the spatial scale of 1 500 km. Within this spatial range, the MW=9.0 event falls into the piece-wise power-law-like frequency-magnitude distribution. Therefore, in the perspective of the critical-point-like model of earthquake preparation, the failure to forecast/predict the approaching and/or the size of this earthquake is not due to the physically intrinsic unpredictability of earthquakes.
文摘当前,无线电引信面临严峻的信息型干扰环境,为保证无线电引信在战场上稳定发挥毁伤效能,抗信息型干扰相关技术成为无线电引信抗干扰领域的研究热点。根据引信干扰机先截获后转发干扰的工作流程,着眼于无线电引信的低截获波束设计,并结合频控阵(Frequency Diverse Array,FDA)-多输入多输出(Multiple-Input Multiple-Output,MIMO)技术独特的S形弯曲阵列方向图,探索基于FDA-MIMO的无线电引信低截获点状波束设计方法。在分析FDA-MIMO的波束函数后,聚焦于阵元频偏设置对波束合成的影响这一关键点。通过将波峰点与功率下降点设置在较近距离范围Δr内,实现在波峰点附近以Δr为半径的较小邻域内波束幅值较大,而在其他范围波束幅值快速下降的目标,进而运用波束函数解算出各阵元频偏,得到以阵元频偏设置公式为核心的低截获点状波束设计方法。仿真结果表明:在低截获点状波束设计方法的指导下,FDA-MIMO波束在距离维半功率波束宽度为1 m和角度维半功率波束宽度为9°,波束汇聚性能和低截获性能明显好于其他经典频偏设置方法;该设计方法为基于FDA-MIMO的无线电引信低截获波束设计提供了理论支撑,可以提高无线电引信的低截获性能,更好的发挥战场毁伤效能。
文摘In this study, we focus into the non-relativistic wave equation described by the Schrodinger equation, specifically considering angular-dependent potentials within the context of a topological defect background generated by a cosmic string. Our primary goal is to explore quasi-exactly solvable problems by introducing an extended ring-shaped potential. We utilize the Bethe ansatz method to determine the angular solutions, while the radial solutions are obtained using special functions. Our findings demonstrate that the eigenvalue solutions of quantum particles are intricately influenced by the presence of the topological defect of the cosmic string,resulting in significant modifications compared to those in a flat space background. The existence of the topological defect induces alterations in the energy spectra, disrupting degeneracy.Afterwards, we extend our analysis to study the same problem in the presence of a ring-shaped potential against the background of another topological defect geometry known as a point-like global monopole. Following a similar procedure, we obtain the eigenvalue solutions and analyze the results. Remarkably, we observe that the presence of a global monopole leads to a decrease in the energy levels compared to the flat space results. In both cases, we conduct a thorough numerical analysis to validate our findings.
文摘针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦合效应,对导引头典型状态的流场进行了模拟,获得了流场的密度、温度、压力等参数和窗口的温度场参数。基于流场参数,利用HyFLOW气动光学传输效应计算功能,开展了红外光学传输成像计算;利用HyFLOW气动光学辐射效应计算模块,开展了流场和光学窗口的热辐射计算。计算结果表明,类THAAD导引头在30 km以上飞行时,流场和光学窗口基本不会影响目标信号的光学传输成像,但流场和窗口的热辐射效应会对导引头识别目标造成影响。不过随着飞行高度的升高,这种影响会减小。
