Daubechies Wavelet Meshless Method for 2-D Elastic Problems

This paper introduces a meshless method based on Daubechies （DB） wavelets for 2-D elastic problems. The scaling and wavelet functions of the DB wavelet are used as basis functions to approximate the unknown field functions, so there is no need to construct costly shape functions as in the finite element method （FEM） and other meshless methods. In addition, the properties of the DB wavelets facilitate implementation of the method. The new method is used to analyze the elastic problem of a plain plate with a circle hole, and the numerical results agree well with the FEM. This method is effective and can be extended to solve complicated two or three dimensional problems.     

甲苯胺蓝共振瑞利散射光谱法测定硫酸皮肤素

在适宜pH条件下,甲苯胺蓝与硫酸皮肤素作用形成结合产物时将导致溶液共振瑞利散射(RRS)明显增强并产生新的RRS光谱,最大散射峰位于356.0 nm处.硫酸皮肤素在0.1～4.0 μg·mL-1范围内与RRS强度成正比;检出限(3σ)为 8.5 × 10-2 μg·mL-1.本文研究了适宜的条件和影响因素,考察了共存物质的影响.实验证明,该方法有较好的选择性和灵敏性;应用于合成样品的测定,结果令人满意.     

一类高阶Rayleigh型方程周期解的存在性

本文利用重合度理论研究一类高阶Rayleigh型方程x(n)(t)+f(x’(t))+g(x(t-τ(t)))=p(t)周期解的存在性,获得了其2π-周期解存在性的若干结论。     

干扰温度约束下的最优源功率控制与协作波束成形

文中研究在主用户干扰温度约束下,如何优化认知源节点发送功率以及认知中继波束成形权值来最大化认知目的节点的信噪比.信噪比最大化问题被转化为广义Rayleigh商问题,最优中继波束成形权值等于相关信道系数与源节点发送功率构成的矩阵的最大特征值所对应的特征向量.文中考虑了严格与宽松两种干扰温度约束,对于严格约束,给出了最优源节点发送功率与中继波束成形权值的解析解;对于宽松约束,推导了包含最优源发送功率的一个紧缩区间,并在该区间内使用基于最速下降的梯度方法有效计算最优解.     

基于广义S变换的动态滤波技术及应用

分频解释技术已广泛应用于地震资料综合解释流程中。以广义Stockwell变换时频谱为基础,提出了一种针对瞬时谱的动态滤波技术,该方法分别对各时刻瞬时谱进行频率域滤波,且各时刻滤波参数由该时刻瞬时谱动态决定。详细介绍了该方法的原理及实现流程;通过单道地震信号分析了动态滤波技术的优势;并结合实际工区和衰减梯度含油气性检测技术,对比了滤波前后检测的衰减异常,得出利用动态滤波方法处理后的地震数据能够更准确的检测气藏的衰减异常,更符合工区实际情况,证实了该方法的可行性和实用性。动态滤波方法为地震信号分频处理提出了一种新思路。     

Influence of cross correlation step length on the surface stress of thin laser cladding Fe314 alloy coatings

To measure the surface stress of thin laser cladding coatings with Rayleigh waves based on the cross correlation function, this paper introduced the influence of cross correlation step length on the stress measurement. Flat-shaped specimens made of laser cladding Fe314 alloy coatings were performed by static tensile tests, and Rayleigh wave signals were collected during the test process with an ultrasonic pulser and receiver instrument combined with two Rayleigh wave transducers. The difference in time of flight between two signals was determined based on the cross correlation function. The microstructure was observed by scanning electronic microscopy. The influence of the stress on the propagation velocity of Rayleigh waves and the relationship between the difference in time of flight and tensile stress under different cross correlation step lengths were analyzed. The inhomogeneous deformation of the coatings affects the relationship between the difference in time of flight and tensile stress; the stress measurement of the coatings is nearly constant with the increase of cross correlation step length when it attains one cycle.     

光栅衍射问题数值计算的最小二乘方法

针对光栅衍射问题提出一种最小二乘算法. 在计算区域简单剖分的基础上, 选取平面波函数近似解的局部性态, 并利用Rayleigh展开的有限项截断近似解在无穷远处的性态. 结果表明, 该方法适用于一般形状的衍射光栅和大波数情形, 应用过程简单, 所需剖分单元少, 收敛速度快. 数值实验验证了算法的有效性.     

RS编码的EBPSK调制解调器性能仿真

EBPSK是一类不对称的二元相移键控调制技术,即在码元周期T内的键控调制时段τ相似文献   

频率分集MC-CDMA在瑞利衰落信道下的性能分析

分析多载波码分多址系统的基带发射、接收信号模型以及多径Rayleigh衰落信道模型,进而提出 一种系统的通用矩阵分析模型。对多载波码分多址系统的单用户理论误码性能进行了深入探讨,给出了一 种新颖的单用户误码率分析方法。数值仿真结果表明:多载波频率分集CDMA系统在无线宽带数据传输中 性能大大优于CDMA具有良好的应用前景。     

Kinetic study of the Rayleigh-Bénard flows

The present paper employs the direct simulation Monte Carlo (DSMC) method to study the Rayleigh-Bénard flows, where the temperature ratio of the upper to lower plate is fixed to 0.1. For a Knudsen number (Kn) of 0.01, as the Rayleigh number (Ra) increases, the flow changes from the thermal conductive state to the convective state at about Ra=1700, and the calculated relation of heat flux through the lower plate versus Ra is in good agreement with classical experimental and theoretical results. For Kn=0.05, ...