高速高精度ADC系统研究

由于单个ADC模拟输入带宽的限制,混合滤波器组ADC系统不能够直接对高达数GHz的模拟信号进行采样.本文提出了基于混频器和低通滤波器的抽取器数学模型,并且从时域和频域进行详细的分析和证明.最后在混合滤波器组ADC系统的基础上,提出了基于混频器和低通滤波器的高速高精度混合滤波器组ADC系统,它完全满足软件无线电和雷达等多个领城的高速高精度要求.     

FPGA芯片的多路模拟信号源设计

基于国产FPGA芯片FMK50设计了一种多路高精度模拟信号源。设计由FPGA控制14位高精度DAC完成D/A转换,将产生的信号通过高速模拟开关及采样保持电路实现96路输出;采用内部ADC配合上位机设计自检模块对96路输出信号进行回采与标定。测试结果表明,系统在100%国产化的基础上稳定输出可配置的0～5 V电压信号且精度优于0.2%FS,自检模块设计大大提高了系统的输出精度及自动化程度。     

Constructing Facial Identity Surfaces for Recognition

We present a novel approach to face recognition by constructing facial identity structures across views and over time, referred to as identity surfaces, in a Kernel Discriminant Analysis (KDA) feature space. This approach is aimed at addressing three challenging problems in face recognition: modelling faces across multiple views, extracting non-linear discriminatory features, and recognising faces over time. First, a multi-view face model is designed which can be automatically fitted to face images and sequences to extract the normalised facial texture patterns. This model is capable of dealing with faces with large pose variation. Second, KDA is developed to compute the most significant non-linear basis vectors with the intention of maximising the between-class variance and minimising the within-class variance. We applied KDA to the problem of multi-view face recognition, and a significant improvement has been achieved in reliability and accuracy. Third, identity surfaces are constructed in a pose-parameterised discriminatory feature space. Dynamic face recognition is then performed by matching the object trajectory computed from a video input and model trajectories constructed on the identity surfaces. These two types of trajectories encode the spatio-temporal dynamics of moving faces.     

Image coding quality assessment using fuzzy integrals with a three-component image model

Based on importance measures and fuzzy integrals, a new assessment method for image coding quality is presented in this paper. The proposed assessment is based on two subevaluations. In the first subevaluation, errors on edges, textures, and flat regions are computed individually. The errors are then assessed using an assessment function. A global evaluation with Sugeno fuzzy integral is then obtained based on the importance measure of edge, texture, and flat region. In the second subevaluation, an importance measure is first established depending on the types of regions where errors occur, a subtle evaluation is then obtained using Sugeno fuzzy integral on all pixels of the image. A final evaluation is obtained based on the two subevaluations. Experimental results show that this new image quality assessment closely approximates human subjective tests such as mean opinion score with a high correlation coefficient of 0.963, which is a significant improvement over peak signal-to-noise ratio, picture quality scale, and weighted mean square error, three other image coding quality assessment methods, which have the correlation coefficients of 0.821, 0.875, and 0.716, respectively.     

填充介质倒梯形脊波导衰减特性的有限元分析

脊波导在传播电磁波的过程中伴随有能量损耗,为了研究填充介质脊波导的衰减特性,本文采用有限元法借助Matlab软件计算了TE模式下部分填充介质倒梯形对称双脊波导的衰减常数和功率容量.分析了脊波导衰减常数和功率容量与脊波导尺寸、工作频率、填充介质相对介电常数之间的关系,给出关系曲线图.这些结果将丰富现有的填充非均匀介质脊波导的数据,为填充介质脊波导的设计和优化提供有价值的依据.     

新时代背景下数据结构教学改革

数据结构课程在计算机及相关专业具有重要的核心地位,但是由于手机控现象、90后特点、信息爆炸等新时代特点使数据结构的课堂效率并不理想.针对这些新时代特点,提出提升课堂魅力、夯实前导课程、客户体验管理、渗透不确定理论、树立正确挫折观、利用网络平台六个对策.通过这六个对策,大大提高了学生的学习积极性,从而提高了教学质量.     

Finite time agreement protocol design of multi‐agent systems with communication delays

In this paper, the finite‐time agreement problem of continuous‐time multi‐agent systems with communication delays is considered. First, the multi‐agent system researched in the paper is described. Second, some notations and lemmas used in the paper are given. Then, agreement protocols for continuous (but non‐smooth) multi‐agent systems are proposed, which ensure that the states of agents reach agreement in finite time. The stability analysis and simulations are presented to show the effectiveness of the method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于云端的未来课堂模型构建研究

未来课堂是针对未来创新人才培养需求、以新课程改革为支撑,以互动为核心,以促进课堂主体和谐、自由发展的一种高效课堂。本文分析了未来课堂的必要性和特性的基础上,构建了基于云端的未来课堂理论模型,该模型对创新教育有一定的借鉴作用。     

A hierarchical test methodology for systems on chip

We present a hierarchical test methodology for testing a SOC with heterogeneous cores, including the 1149.1-wrapped, P1500-wrapped, and BIST memory cores. We propose an 1149.1-based hierarchical test manager that also provides P1500 test control signals. This scheme includes a memory BIST interface, providing both serial and parallel access ports for BIST circuits. Our approach offers low area and pin overhead, and high flexibility     

钙[Ca(NO3)2和CaO]对茶树氟吸收的影响

通过水培和土壤盆栽试验,研究了Ca对茶树F吸收的影响。结果显示,在含F溶液中添加Ca显著降低茶树对F的吸收。在土壤盆栽试验中也得到了类似结果,在2种土壤F含量条件下,加入Ca(NO3)2后显著降低茶树成熟叶和新梢F含量。同样土壤加入CaO后,显著降低茶树对F的吸收。土壤分析表明加入Ca(NO3)2后并没有显著改变土壤水溶性F含量,而加入CaO后还增加了土壤水溶性F含量。因此,Ca减少F吸收可能并不单纯是因为形成CaF2后降低土壤F的有效性。