多旋翼无人机微多普勒特性分析与特征提取

针对多旋翼无人机目标的识别问题，提出一种基于伽柏（Gabor）变换的瞬时频率估计与快速傅里叶变换（FFT）相结合的微多普勒特征提取算法。首先建立多旋翼无人机旋翼回波模型，并通过仿真分析叶片数目、旋翼转速和初始相位等参数对微多普勒特征的影响，利用Gabor变换得到时频特征。在此基础上通过瞬时频率极大值法提取微多普勒频率，并对瞬时频率采用FFT提取旋翼数和转动频率，从而获得叶片长度估计值。实测数据验证了该算法较为准确地提取无人机的微多普勒参数。     

基于马尔可夫模型的容错系统可靠性分析

容错系统的可靠性分析是容错系统设计过程中最重要的步骤之一.在容错控制系统的可靠性分析中,利用马尔可夫过程和半马尔可夫过程理论对容错系统进行可靠性建模能够较为真实地描述系统的实际工作情况.但是,由于容错系统为了达到高可靠性而采用了大量的冗余配置及重构技术,使得该可靠性模型往往变得相当复杂.因此,对系统可靠性模型进行必要的化简,可以减少许多计算量并使该模型更加符合实际使用要求.     

试卷质量和考试成绩评判指标的分析研究

本文对试题警告系数、考试成绩的信度、考试成绩的效度及学生警告系数的计算式做了修正 ,使之能适合计算机处理。提出试卷平均得分、试卷区分度、试卷警告系数和学生试卷得分度评判指标 ,使试卷质量 ,教学质量和学生学习水平的评判量化 ,可用于教学评估     

平稳正态过程反正弦定理在信号谱估计中的应用

本文利用平稳过程反正弦定理估计了信号的相关西数和话密度，实例计算表明本文所述方法与实测结果相当一致。     

The fourth dimension: A motoric perspective on the anxiety–performance relationship

This article focuses on raising concern that anxiety–performance relationship theory has insufficiently catered for motoric issues during, primarily, closed and self-paced skill execution (e.g., long jump and javelin throw). Following a review of current theory, we address the under-consideration of motoric issues by extending the three-dimensional model put forward by Cheng, Hardy, and Markland (2009) (‘Toward a three-dimensional conceptualization of performance anxiety: Rationale and initial measurement development, Psychology of Sport and Exercise, 10, 271–278). This fourth dimension, termed skill establishment, comprises the level and consistency of movement automaticity together with a performer's confidence in this specific process, as providing a degree of robustness against negative anxiety effects. To exemplify this motoric influence, we then offer insight regarding current theories’ misrepresentation that a self-focus of attention toward an already well-learned skill always leads to a negative performance effect. In doing so, we draw upon applied literature to distinguish between positive and negative self-foci and suggest that on what and how a performer directs their attention is crucial to the interaction with skill establishment and, therefore, performance. Finally, implications for skill acquisition research are provided. Accordingly, we suggest a positive potential flow from applied/translational to fundamental/theory-generating research in sport which can serve to freshen and usefully redirect investigation into this long-considered but still insufficiently understood concept.     

基于核密度估计多样性采集的背景建模算法

1IntroductionBackground subtraction methods are extensively ex-ploited for moving object detection in videos in manyapplications ,such as traffic monitoring[1],human mo-tion capture[2]and video surveillance[3]. The centralidea behind such methods is to segment foreground ini mage sequences taken from a fixed camera by com-paring each newframe to a model of the scene back-ground . Therefore , correctly and efficiently modelingand updating the background model is one of the mostchallenging aspec…     

Curvatures estimation on triangular mesh

Curvatures are important geometric attributes of surfaces. There are many applications that require as a first step the accurate estimation of curvatures at arbitrary vertices on a triangulated surface. Chen and Schmitt (1992) and Taubin (1995)presented two simple methods to estimate principal curvatures. They used circular arcs to approximate the normal curvature. We find this may cause large error in some cases. In this paper, we describe a more accurate method to estimate the normal curvature,and present a novel algorithm to estimate principal curvatures by simplifying the Chen and Schmitt's method. Some comparison results are also shown in this paper.     

一种在MPEG-4编码过程中提高实时性的算法

本文提出了一种新的在MPEG-4编码过程中提高实时性的算法。算法采用双重筛选机制,充分利用了运动估计的结果提取运动对象。首先在运动估计过程中加入背景优先准则进行第一重筛选;然后根据运动估计后宏块的最小平均绝对差值分利用区域自适应门限进行第二重筛选,从而获得运动区域掩模;最后对掩模进行形态滤波和填充消除噪声点,最终得到运动区域。算法分别在硬件和软件平台上进行测试,结果表明提出的算法得到了理想的分割效果,较传统的在编码前进行运动对象提取的方法实时性大大提高了。     

区间时变细胞神经网络周期解的鲁棒指数稳定性

本文研究一类区间时变扰动神经网络系统周期解的鲁棒指数稳定性.获得了一系列关于鲁棒指数稳定性的判据.     

人工海水的配制及经济可行性评估

按天然海水成份，由NaCl、MgCl2、CaSO4、K2SO4等无机盐配制人工海水，海水中含盐量3.5％左右，其配方简单，成本低廉，是制造人工海水好方法。