一种适用于GSM/WCDMA的双模有源RC低通滤波器

设计实现了一种基于SMIC 0.18μm CMOS混合信号工艺的4阶有源RC低通滤波器(LPF)。该LPF同时满足GSM和WCDMA的带宽性能,并且在两种模式下有元件最大的共享度。由于GSM和WCDMA的带宽存在很大的差异,给滤波器的设计带来了很多问题,例如噪声与线性度,功耗和面积等之间的平衡。该滤波器具有高线性度的特点。     

基于ASM的人脸特征点自动标定

针对经典弹性图匹配算法中人脸特征点的定位问题,本文提出了一种利用机器自标定来代替传统的手工标定的算法.本文算法首先利用可变形状模型拟合出人脸的轮廓,得到人脸关键特征点位置的初始估计,然后利用参考图像中对应特征点的Gabor系数调整初始位置,最终实现关键特征点的精确定位.实验结果表明,算法可以有效地定位出人脸特征点,定位结果稳定.     

激光主动探测系统的探测能力分析

为了能够准确获取"猫眼"光学系统激光反射回波信号方向性和发散度的信息,基于光学系统"猫眼"效应和高斯光束的变换规律,依据激光大气传输的衰减和强度闪烁特性,给出了激光主动探测系统回波能量衰减和起伏的数学模型.结合野外试验分别对焦平面光学系统和离焦光学系统的关键指标进行了工程计算、分析论证和比较,结果表明:在激光主动探测系统探测识别时,可根据回波信号强度来识别不同类型的目标:同时对激光在大气传输中能量的衰减和光强的起伏进行了工程计算和分析论证,结果表明:大气湍流会大幅度降低激光主动探测系统的探测距离.     

设计有源天线的一种新方法

本文对用一种负阻抗变换电路同电小天线导线相结合构成的有源天线进行了理论分析．并给出了该有源天线稳定的工作条件．分析结果表明：用该方法设计的有源天线具有较高的灵敏度和较小的最佳天线尺寸．实验结果证实该方法有效．     

Optimal Control of Elliptic Variational Inequalities

Optimality systems for optimal control problems governed by elliptic variational inequalities are derived. Existence of appropriately defined Lagrange multipliers is proved. A primal—dual active set method is proposed to solve the optimality systems numerically. Examples with and without lack of strict complementarity are included. Accepted 5 March 1999     

1:2 and 1:3 internal resonance active absorber for non-linear vibrating system

Vibration and dynamic chaos should be controlled in either structures or machines. An active vibration absorber for suppressing the vibration of the non-linear plant when subjected to external and parametric excitations is studied in the presence of one-to-two and one-to-three internal resonance. The main attention is focused on the study of the active control and stability of two systems, which can be used to reduce vibrations due to rotor blade flapping motion. The method of multiple scale perturbation technique is applied to determine four first-order non-linear ordinary differential equations that govern the modulation of the amplitudes and phases in the presence of internal resonance of the two systems with quadratic and cubic order of control. These equations are used to determine the steady state solutions and their stability. The stability study of non-linear periodic solution for two cases (1:2 and 1:3 internal resonance) and the stability of the obtained numerical solution are investigated using frequency, force-response curves and phase-plane method. Also, effects of some parameters on the steady state solution of the vibrating system are investigated and reported in this paper. Variation of some parameters leads to the bending of the frequency, force-response curves and hence to the jump phenomenon occurrence. The reported results are compared to the available published work.     

Active,self-motile,and driven emulsions

In this review, we focus on recent experiments involving transport and other dynamical aspects of emulsified droplets under nonequilibrium conditions. We include both active emulsions, where individual droplets develop self-propulsion or self-sustained motion at the expense of local energy sources, and driven emulsions, where droplets are activated through the local transduction of an external source. A common theme in the reported scenarios is the use of hybrid colloidal systems, where emulsions and liquid crystals are interfaced, providing with a rich scenario that features phenomena and mechanisms not found in traditional emulsions.     

The generation and use of graphical examples in calculus classrooms: The case of the mean value theorem

We analyzed video data of five instructors teaching the Mean Value Theorem (MVT) in a first-semester calculus course as part of a broader project investigating how active learning strategies were being implemented and supported in calculus courses. We sought to identify the ways examples of functions that did or did not satisfy the conclusion of MVT were generated and used in instruction. Using thematic analysis, we identified four themes that serve as characterizations of examples, which then allowed for the analysis of trends and patterns. We propose that attention to the generation and use of examples serves as one lens for considering how students can be engaged in the mathematical activity of the classroom, with implications for learning. This work contributes to an evolving notion of what is entailed in students’ active learning of mathematics and the role of the instructor in facilitating active learning opportunities.     

Sampling schemes and recovery algorithms for functions of few coordinate variables

When a multivariate function does not depend on all of its variables, it can be approximated from fewer point evaluations than otherwise required. This has been previously quantified e.g. in the case where the target function is Lipschitz. This note examines the same problem under other assumptions on the target function. If it is linear or quadratic, then connections to compressive sensing are exploited in order to determine the number of point evaluations needed for recovering it exactly. If it is coordinatewise increasing, then connections to group testing are exploited in order to determine the number of point evaluations needed for recovering the set of active variables. A particular emphasis is put on explicit sets of evaluation points and on practical recovery methods. The results presented here also add a new contribution to the field of group testing.     

A four-switch shunt active filter based on one cycle control for compensating non-linear loads

ABSTRACT

This paper introduces a Four-Switch Three-Phase Shunt Active Power Filter (FSTP-APF) based on One Cycle Control (OCC) technique for compensating the currents of three phase non-linear loads. The power stage of FSTP-APF uses only four semiconducting switches which leads to reduce the overall cost of APF. The proposed technique retains the advantages of the conventional OCC, such as no reference current calculation, no need for using Phase-Locked Loop (PLL), very simple control circuit and constant switching frequency. In addition, the modification reduces the number of semiconductor switches, reduces the filter output inductances, reducing the number of sensors to only four sensors, two of them for measuring supply currents and the others for measuring DC-link voltages, and the control algorithm becomes simpler. The feasibility and performance of the proposed technique are demonstrated through the simulation and experimental verifications.