非牛顿幂律流体有界双重介质渗流模型实空间解析解与样版曲线

在前人工作的基础上,建立了非牛顿幂律流体有界双重介质试井模型.根据模型的特点,提出了相应的特征值问题,求出了特征值和特征函数.定义了油层压力关于空间变量的正交积分变换.根据特征函数系的完备正交性和矩阵微分方程理论,获得了油层压力分布以及井底压力,压力导数的实空间解析解(无穷级数形式).首次直接根据实空间解析解绘制了样版曲线,并在同一张双对数坐标纸上描出拉普拉斯方法制作的样版曲线,同时给出二者间的误差走势图.通过对比分析发现,随着级数项数的增大,根据解析解制作的样版曲线逐渐逼近拉普拉斯方法制作的样版曲线.新疆油田实例证实了该方法的有效性.研究结果进一步补充,完善了试井分析理论.     

红外双视场光学系统的初始结构求解

介绍了红外双视场光学系统的变焦理论和二次成像理论,利用高斯成像原理物像交换原则求解了各透镜组元的焦距及间隔,详细介绍了双分离镜组初始结构的求解方法.分析了利用PW方法进行求解的基本理论.最后根据上述理论设计了基于中波红外致冷型320×240元凝视焦平面阵列的红外双视场光学系统,并利用光学调制传递函数对其像质进行了评价....     

一种应用于WLAN相位可调的本振缓冲器

该文提出了一种应用于WLAN相位可调的本振缓冲器,用于校准直接下变频收发机的I/Q两路不平衡。该电路通过开关输入MOS管源极的电容阵列,延迟本振信号,从而调节信号的相位。该文采用SMIC 0.18m工艺实现了4.8~6GHz的I/Q两路本振缓冲器的设计,其版图面积为650550m2。仿真结果表明,在5位控制字作用下,I或者Q路本振缓冲器的相移在0~8的范围内呈现近乎线性的变化,而本振缓冲器的输出功率的变化范围只有0.2dB。     

基于双积分模拟重构大动态范围CIS系统研究

提出一种采用列共用模拟重构电路和双积分三采样工作时序的CMOS图像传感器(CIS)系统架构,可实现光电响应曲线压缩和像素固定模式噪声(FPN)消除,提高传感器动态范围到83 dB,使成像质量提高.该结构具有与单采样相同的像素阵列,仅增加很小的处理电路.改进的工作时序优化了长积分、短积分和信号处理的时序分配.系统控制由FPGA实现.功能和数模混合仿真验证表明,方案是可行的.     

介观金属双环系统中的量子效应

基于电荷离散化的事实,运用最小平移算符的性质,计算介观金属双环系统中电荷、电流以及能量的量子涨落,研究影响量子涨落的因素.结果表明:量子电流、量子能谱的量子涨落不仅与介观金属环的电参量、Plank常数有关,而且还明显地依赖于电荷的量子化性质.     

A Dual Approach for Solving Nonlinear Infinity-Norm Minimization Problems with Applications in Separable Cases

In this paper,we consider nonlinear infinity-norm minimization problems.We device a reliable Lagrangian dual approach for solving this kind of problems and based on this method we propose an algorithm for the mixed linear and nonlinear infinity- norm minimization problems.Numerical results are presented.     

受控源“电阻性”和“有源性”的研究

首先对受控源的电阻性和有源性进行了分析,然后比较完整系统地讨论了受控源的双重特性在线性时不变含受控源网络中的作用,并通过实例说明了受控源的双重特性在电路等效变换以及叠加定理中的具体的应用。     

A study of gridless method with dynamic clouds of points for solving unsteady CFD problems in aerodynamics

When solving unsteady computational fluid dynamics problems in aerodynamics with a gridless method, a cloud of points is usually required to be regenerated due to its accommodation to moving boundaries. In order to handle this problem conveniently, a fast dynamic cloud method based on Delaunay graph mapping strategy is proposed in this paper. A dynamic cloud method makes use of algebraic mapping principles and therefore points can be accurately redistributed in the flow field without any iteration. In this way, the structure of the gridless clouds is not necessarily changed so that the clouds regeneration can be avoided successfully. The spatial derivatives of the mathematical modeling of the flow are directly determined by using weighted least‐squares method in each cloud of points, and then numerical fluxes can be obtained. A dual time‐stepping method is further implemented to advance the two‐dimensional Euler equations in arbitrary Lagarangian–Eulerian formulation in time. Finally, unsteady transonic flows over two different oscillating airfoils are simulated with the above method and results obtained are in good agreement with the experimental data. Copyright © 2009 John Wiley & Sons, Ltd.