Reconstruction algorithm of computerized ionospheric tomography

Applying the technique of computer tomography to ionosphere detection, Computerized Ionospheric Tomography (CIT) can produce the large scale distribution of electron density in a two dimentional longitudinal section of ionosphere. According to the actual detecting condition of sparse receiver and limited projecting angle, polynomial interpolation method and projecting angle expansion method are proposed. A new energy function is formulated according to the constraint of least neighbourhood error. Simulated annealing is incorporated in the iteration of ART to get the global minimum of energy function. Sun Xiaon; born in May 1968, Ph. D. Current research interest is in computer graphics & Image processing Supported by the National Natural Science Foundation of China     

Two methods to solve the ionospheric electron concentration horizontal gradient at Chongqing

The electron concentration horizontal gradient vector of the ionosphere and its south-north and east-west components over Chongqing station are analyzed and calculated, using the first approximation, time correlation and space correlation and another approach introduced. And then, the validity of the two methods is analyzed and compared. Foundation item: Supported by the National Natural Science Foundation of China (69571020) and the Research Fund for the Doctoral Program of Higher Education (RFDP1999048602) Biography: Chong Yan-wen(1972-), male, Ph. D. candidate, research direction: ionospheric modeling and inversion.     

The research progress on lateral shift of reflected electromagnetic wave at the interface of two conductive media

In this paper the research status of lateral shift of reflected electromagnetic wave at the interface of conductive media was reviewed, the lateral shift and the lateral delay were analyzed, and the charac- teristic of lateral shift curves varying with the angle of incidence was introduced in detail. For electro- magnetic wave logging, the error correction method of lateral shift was stressed in this paper, the magnitude of measured errors caused by the lateral shift was established. It is noticed that the longer wavelength, the larger error of measured results. With respect to the effect of lateral shift, the problem which still needs to be settled in the measurement of electromagnetic wave, as well as prospects on the further research and applications of lateral shift are described.     

短波单站定位中电离层的模型选择与修正

短波单站定位实现了仅用一个测向站就能确定短波发射台的方向及位置,在短波单站定位中,影响单站定位精度的主要因素来源于电离层模型及电离层参数是否与实际情况相符.作者介绍了短波单站定位机理和两种实用的电离层模型,并对基于这两种电离层模型的射线反跟踪算法进行了分析比较.为了进一步提高单站定位精度,还提出了利用已知台修正电离层模型,并设计实现了该模型.     

无序对准一维矢势束缚中无质量Dirac电子的影响

通过有限差分的方法,数值计算了一个相对论性质的Dirac电子在磁场和无序同时存在时的能谱结构,并讨论了不同磁场强度和无序强度时电子密度分布的变化情况.结果发现:随着无序强度的增大,无序势削弱了磁场对电子的捕获,使局域化现象减弱,使得无质量Dirac电子出现了有别于Anderson局域化的现象.     

加强层的设置对超高层框筒结构水平位移的影响

分析了加强层对控制结构水平位移的力学过程,建立了8个带有水平加强层的框架-核心筒高层结构模型（本文的基本模型是以西安市某大厦为背景,主体结构37层,塔楼2层,地下2层;结构总高度158．80m。下部采用桩筏基础。在这个模型基础上稍作改动,将其中的第4层、17层、37层做成加强层,产生7个新模型）。并用有限元软件分析了水平地震荷载作用下结构的顶点位移和最大层间位移,并根据理论分析和一系列数值比较,得出了加强层的设置数量和最优位置的结论。另外提出了对梁式加强层提高结构抗侧刚度的有效手段。研究结果可供实际工程参考。     

局域波法的多分辨分析特性及其应用

局域波法通过局域波分解和瞬时频率的求解,将任何复杂的信号分解成为有限数目并且具有一定物理意义的基本模式分量,每一个分量描述了时变信号中不同频率和尺度范围的固有振动模式,所获得的各分量局域波时频分布具有多分辨分析特征.由于局域波分解是自适应的,它的多分辨分析特征也是自适应的.经理论分析与对变速箱轴承座处拾取的振动信号的分析验证了方法的有效性,局域波法为工程测试中的时频分析提供了一种有效的手段.     

Relating the probability distribution of a de Broglie wave to its phase velocity

We show that the phase velocity in a stationary state of a de Broglie wave can be directly obtained from the probability distribution, i.e. the quantum trajectories, without detailed knowledge of the phase term itself. In other words, the amplitude of a de Broglie wave function describes not only the probability distribution but also the phase velocity distribution. Using this relationship, we comment on two calculations of the Goos-H nchen shift in de Broglie waves.     

基于数字测高仪和 GPS 观测的三亚地区电离层-等离子体层总电子含量特征分析

基于2012年海南三亚台站(18.34°N,109.62°E)的数字测高仪和GPS观测资料,分别研究了数字测高仪和GPS反演得到的总电子含量、等离子体层总电子含量(PTEC)的变化特征.结果显示:GPS观测得到的总电子含量(GTEC)与数字测高仪观测得到的总电子含量(ITEC)的变化特征一致,PTEC和PTEC占GTEC的百分比变化具有明显的日变化特征.PTEC数值在3~22 TECU(1 TECU=10~(16)el/m~2)范围内变化,PTEC的极大值大约出现在地方时日落时分,PTEC极小值大约出现在地方时日出时分,PTEC占GTEC百分比在夜间一般能达到40%左右,甚至能达到80%,白天一般在20%以下.     

基于CUDA技术城市小区电波传播并行计算的研究

无线电射线跟踪效率一直是电波传播场强模拟预测的核心问题之一。随着计算统一设备架构(compute u-nified device architecture,CUDA)技术的提出彻底改变传统的x86硬件架构体系,从硬件底层上为并行计算提供了可能。在CUDA被提出用于通用计算的前提下,提出了CUDA技术与射线跟踪相结合,介绍了CUDA如何实现异构体计算,如何在CUDA硬件平台上实现并行化编程,然后通过一个简单的三维地理数据模型实现了无线电波射线跟踪的并行化计算。最后对实验结果进行了分析与总结,证明CUDA技术能很好地提高运算效率。     

钢管混凝土嵌岩桩力学性能研究综述

钢管混凝土嵌岩桩在内河航运工程中的应用日趋广泛。钢管作为混凝土填充的模板和钢筋,实现了每种材料(混凝土和钢)的最佳性能,同时提供两种材料相互补充,以缓解不良的失效模式。填料增加了管道的抗压强度和刚度,延迟和抑制了管道的局部屈曲,并在复合作用下提高了管道的延性和阻力。从理论、数值和试验分析的角度阐述了钢管混凝土嵌岩桩研究现状,包括横向承载特性、纵向承载特和钢-混凝土界面力学特性。最后对钢管混凝土嵌岩桩尚待研究的问题进行了展望,研究分析认为钢-混凝土界面局部劣化和发展是未来钢管混凝土嵌岩桩力学性能研究重点。     

Climatological analysis and modeling of the ionospheric global electron content

In this paper, we calculate the ionospheric global electron content （GEC） from the GPS TEC data along the geographic longitude 120°E during the period of 1996-2004, and investigate the relationship between GEC and 10.7 cm solar radio flux F10.7 and its seasonal dependence with partial correlation analysis. Our results show that GEC is closely correlated with solar activity index F10.7 and is also related with annual and semiannual variations. An empirical GEC model driven by those factors is then to examine the influences of different solar activity proxies for the model input. The results suggest that GEC mainly depends on solar activity and the seasonal variations; the latter is also modulated by solar activity. Furthermore, the magnitude of semiannual variation is a little greater than that of annual variation. Our empirical GEC model is proved to be better than the model proposed by Afraimovich et al.     

苯分子的溴代反应研究

应用量子化学密度泛函理论在UB3LYP/6-31G（d）水平上, 结合MP4和AM1方法研究了苯的溴代反应过程. 计算结果表明, 这是包括一个过渡态和两个中间态的多步反应, 反应过程中Br⁺所带的正电荷经正离子中间体［C₆H₆Br］⁺转移给H, 是电子转移过程.     

水平荷载作用下群桩效率及影响因素分析

水平荷载作用下的群桩效率是影响群桩基础水平抗力的重要参数.基于弹性叠加原理,在假设岩土体的应力扩散角恒定的同时,考虑了岩土体物理参数对相邻桩干涉效应的影响,重新推导了不同排列形式下单桩的群桩效应系数,并基于群桩效应系数,求解了1×2、2×2、3×3布置形式的群桩效率公式.同时通过有限元研究桩距与桩径比、弹性模量及泊松比...     

CH_3X键断裂电子转移反应的密度泛函理论研究

用密度泛函理论 (DFT)研究CH3 X的键断裂电子转移反应。从几种计算方法的结果比较中选出B3 LYP的DFT方法。随后用B3 LYP方法优化CH3 X的结构 ;计算CH3 X的键断裂电子转移反应的能量变化 ;找到了过渡态并进行了验证。     

隧道内圆极化电磁波传播特性的研究

交通隧道的发展要求实现全程的无线通信.运用波导理论及格林函数法对固极化电磁波在长直圆形隧道中的场分布及传播特性进行了研究,得到了轴向距离的电场分布计算表达式,与已有隧道内传播损耗模型的比较也表明此模型更准确有效,其结果对于隧道内通信网络的优化有一定的指导意义.     

氯诺昔康的NMR研究

用1H NMR,1H-1H COSYdftp技术研究了新抗炎药物氯诺昔康,并对其氢谱进行了归属.     

杜氏藻细胞的无性增殖过程

杜氏藻细胞的无性增殖过程刘广发，楼士林（生物学系）由于杜氏藻富含蛋白质、甘油和β－胡萝卜素等物质，美、澳、以等国自７０年代起已竞相投入巨资进行研究和大规模养殖￣［１，２］。杜氏藻通常以细胞纵裂方式进行无性增殖￣［３］。本文借助光学和电子显微镜观察，剖...     

正态分布根方差的估计及其应用

用四分位极差的方法估计正态分布的根方差,研究了子样四分位极差及根方差估计的密度函数,并结合实例,说明了四分位极差估计具有稳健性.