RLC暂态电路的理论分析和数值模拟

利用Maple符号计算软件做RLC电路方程的拉普拉斯变换,得到电路的精确解,绘制解的图像,并且理论分析了这些解的特点,得到了一些有助于教学应用的结论.     

The impulse response function of apertured and misaligned ABCD optical system in phase-space

By expanding the aperture into complex Gaussian functions, the approximate analytical impulse response function of apertured and misaligned ABCD optical system in phase-space is determined, which allows us to formulate the input-output relation completely in terms of Wigner distribution functions. Its shown that the hard-aperture placed before the optical system will change the shape of output signal Wigner distribution and the misalignment of optical system will introduce the output Wigner distribution function a coordinate shift in phase-space. For examining the analytical results some numerical simulation are done and the graphical results as well as the absolute errors between analytical results and numerical integral ones are presented.     

基于倒双谱的套管井声学评价系统特性辨识

将发射探头(T)、接收探头(R)和TR之间介质视为套管井声学评价系统的组成部分，由套管井声波测井响应，采用倒双谱技术辨识该声学系统的冲激响应，计算得到了该声学系统的特性曲线(冲激响应曲线)。当T、R同时位于自由套管区域时，声学系统特性曲线幅度最高，并且曲线的两端和中心点附近都有比较大的起伏；当T、R同时位于水泥完全胶结区域时，特性曲线幅度最低且比较平坦；随着T、R间窜槽面积的增大，特性曲线幅度逐渐增加并且中心点附近幅度的增加比较明显。通过对该声学系统特性的辨识，从冲激响应曲线瀑布图中可直观反映出套管井水泥胶结的质量。该方法对丰富、完善声波水泥胶结测井资料解释工作具有重要参考价值。     

Feasibility of subjective speech intelligibility assessment based on auralization

Subjective speech intelligibility can be assessed by speech recorded in an anechoic chamber and then convolved with room impulse responses that can be created by acoustic simulation. The speech intelligibility (SI) assessment based on auralization was validated in three rooms. The articulation scores obtained from simulated sound field were compared with the ones from measured sound field and from direct listening in rooms. Results show that the speech intelligibility prediction based on auralization technique with simulated binaural room impulse responses (BRIRs) is in agreement with reality and results from measured BRIRs. When this technique is used with simulated and measured monaural room impulse responses (MRIRs), the predicted results underestimate the reality. It has been shown that auralization technique with simulated BRIRs is capable of assessing subjective speech intelligibility of listening positions in the room.     

空间双折射干涉滤光器的主动补偿研究

 空间太阳望远镜中的双折射干涉滤光器对于温度的变化十分敏感,传统的滤光器在空间环境中很难做到高精度的温度控制。改进传统滤光器的结构,在每一单级中加入LCVR(液晶位相延迟器),通过LCVR主动引入的附加位相延迟补偿由于温度波动引起的晶体位相延迟,可使滤光器透过率峰值波长始终保持稳定。以Lyot滤光器为研究对象,通过理论计算和模拟分析证明了该方法的可行性。该方法应用到空间双折射干涉滤光器可以使滤光器在卫星制造部门提供的环境温度下不使用任何温控系统依然正常使用,成功解决了空间双折射干涉滤光器温控精度的问题。由于摒弃了传统的两级温控装置,有效减小了滤光器的体积,减轻了滤光器的质量,使其更符合空间有效载荷的使用要求。     

系统电磁脉冲综合环境中导线响应的计算

采用时域有限差分法(FDTD)、粒子模拟(PIC)方法和Holland细线算法,对圆柱腔体内带负载导线的系统电磁脉冲(SGEMP)综合环境响应进行了模拟。计算结果表明:导线负载上的响应电流从大到小依次由透射X射线、SGEMP场和前向电子产生;透射X射线和前向电子产生的响应电流极性相反;SGEMP场在导线负载上响应电流的极性与场分布有关;3种环境在负载上的综合响应中透射X射线的响应最大。对于腔体内的导线来说,SGEMP综合环境防护时透射X射线是重点考虑的因素。     

线性压缩机驱动的微型同轴脉冲管制冷机寿命试验

介绍了一种用于测试线性压缩机驱动的微型同轴脉冲管制冷机系统可靠性的试验系统 ,此试验台的建立将用来获得目前国内的同类系统的可靠性数据 ,为今后此种制冷系统用于国防、航空、航天打下基础     

用拉普拉斯变换得到N维谐振子的精确解

通过拉普拉斯变换可以把N维谐振子的Schr?dinger方程退化为一次微分方程，然后得到精确的束缚态解。结果显示这种求解Schr?dinger方程方法跟低维一样可以代替标准的函数分析方法。     

坐席低谷效应的时域有限差分多项模拟

介绍了交错网格下,以声压和质点振动速度为声场参量的室内声学时域有限差分递推格式,给出了在建筑边界截断计算区域的边界条件差分格式。在水平地面房间模型下,应用时域有限差分法模拟了坐席低谷效应对于空间和时间的多种特性;此外,模拟了地面起坡时的低谷效应。     

系统电磁脉冲综合环境中导线响应的计算

采用时域有限差分法(FDTD)、粒子模拟(PIC)方法和Holland细线算法,对圆柱腔体内带负载导线的系统电磁脉冲(SGEMP)综合环境响应进行了模拟。计算结果表明：导线负载上的响应电流从大到小依次由透射X射线、SGEMP场和前向电子产生;透射X射线和前向电子产生的响应电流极性相反;SGEMP场在导线负载上响应电流的极性与场分布有关;3种环境在负载上的综合响应中透射X射线的响应最大。对于腔体内的导线来说,SGEMP综合环境防护时透射X射线是重点考虑的因素。     

ST-X石英基片上铬栅阵中单根栅条反射系数实验研究

精确的栅条反射系数对于声表面波器件的设计至关重要。本文利用网络分析仪的时域功能,采用短脉冲方法实验研究了ST-X石英基片上铬栅阵中单根栅条的反射系数。并推导出计算反射系数的公式。实验测量了不同铬膜厚度条件下单根指条的反射系数,再对实验结果作最小方差法拟合,得到反射系数随铬膜厚度变化的表达式,即反射系数中压电短路贡献和铬的力学负载贡献之和。最后将实验结果与采用有限元方法计算的理论结果比较,发现两者基本吻合。     

脉冲响应法测量混响时间技术的研究

本文介绍了一种根据厅堂脉冲响应特性,利用计算机数字信号处理技术,迅速,准确地测量混响时间的实现方法。     

A hybrid model for the acoustic response of a two-dimensional rough surface to an impulse incident from a refracting medium

A numerical model to calculate the impulse response of a two-dimensional, impenetrable, rough surface directly in the time domain has been recently introduced [J. Acoust. Soc. Am. (2000) 107, 27]. This model is based on wedge diffraction theory and assumes that the half-space containing the source and receiver is homogeneous. In this work, the model is extended to handle media where the index of refraction varies with the distance to the surface by merging the scattering model with a ray-based propagation model. The resulting hybrid model is tested against a Finite-Difference Time-Domain (FDTD) method for the problem of backscattering from a corrugated surface in the presence of a refractive layer. This new model can be applied, for example, to calculate acoustic reverberation from the sea surface in cases where the water mass is inhomogeneous and in the presence of a subsurface bubble layer at low frequencies where dispersion is negligible. It can also be used for atmospheric propagation problems where there is a sound speed gradient overlying rough terrain.     

Effect of carrier transit time on the bandwidth of traveling-wave photodetector

We present an impulse response of traveling-wave photodetector considering the photo-excited carrier transit time as well as the velocity mismatch between lightwave and microwave. The transit time effect on the bandwidth is found to be more significant than the velocity mismatch effect, if the thickness of the intrinsic absorption region is over 0.2μm. The effect of the intrinsic absorption region thickness is also examined. The optimal thickness of the intrinsic absorption region is determined considering the transit time, the optical confinement factor, and the velocity mismatch.     

Experimental verification of the parasitic bipolar amplification effect in PMOS single event transients

The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event charge collection is composed of diffusion, drift, and the parasitic bipolar effect, while for PMOSs in the special layout, the parasitic bipolar junction transistor cannot turn on. Heavy ion experimental results show that PMOSs without parasitic bipolar amplification have a 21.4% decrease in the average SET pulse width and roughly a 40.2% reduction in the SET cross-section.     

Nearsightedness-related indices of finite systems based on linear response function: one-dimensional cases

ABSTRACT

We have investigated nearsightedness of electronic matter (NEM) of finite systems on the basis of linear response function to examine theoretical foundation of contemporary computational chemistry such as quantum mechanics/molecular mechanics methods. In this study, we introduce several nearsightedness-related indices to assess the magnitude of localisability of responses for one-dimensional finite model systems. We started from two electrons' systems, which are beyond the scope of the original concept of NEM, and increased the number of electrons (N) to a hundred electrons to analyse dependency of such indices on N. In the process of construction of the indices, we analysed the factors, because of which the magnitude of nonlocal parts of linear response functions becomes small, into several ones, and extracted purely the magnitude of propagation of responses.     

12 MeV直线感应加速器主开关的优化设计

 介绍了12MeV直线感应加速器主开关的一种优化设计。在保持原有主开关的设计风格和接口结构的条件下，通过优化设计局部结构和调整开关电极尺寸，把主开关的结构电感从63.7nH减小到35nH，使得加速腔的高压脉冲前沿从39.6ns减小到27ns，从而有利于提高12MeV直线感应加速器的性能，验证了优化设计的可行性。     

模拟封闭声场脉冲响应的圆锥束跟踪法

本文简要介绍了声场脉冲响应计算机模拟技术的基本状况,给出了一种将虚源法和声线法相结合的模拟方法－圆锥束跟踪法的原理和算法,并将其对一个实例的计算结果与虚源法进行了比较,最后对其实现过程中需要注意的问题进行了讨论。     

Laplace Sequences of Surfaces in Projective Space and Two-Dimensional Toda Equations

We find that the Laplace sequences of surfaces of period n in projective space P _n–1 have two types, while type II occurs only for even n. The integrability condition of the fundamental equations of these two types have the same form