基于位置预测的靶场图像实时判读方法

在靶场经纬仪对目标实时跟踪测量时,会发生相机随机抖动的情况,引起目标在图像中大幅度运动。应对大幅度运动时,基于搜索窗口的跟踪方法容易丢失目标,而基于全图搜索的跟踪方法时效性差。针对以上问题,提出一种结合核相关滤波算法(Kernelized Correlation Filter, KCF)和目标位置预测的改进的跟踪学习检测算法(Tracking-Learning-Detection, TLD)跟踪框架。利用正交多项式最优线性滤波器及相机角度信息预测目标下一帧位置,在此区域利用KCF进行快速跟踪,可以提高跟踪的成功率和时效性,跟踪失败时再进行检测。仿真实验表明,最优线性滤波器能较准确预测目标位置,给KCF提供较准确的搜索位置,算法每帧耗时仅为1.1 ms,且定位精度优于TLD和KCF,能有效应对相机抖动的问题。靶场实际试验证明该方法可提高靶场自动判读水平,减少人工干预。     

多管火箭武器储运发射箱长期储存蠕变性能预测

为探究火箭武器储运发射箱长期储存的蠕变性能,制备复合材料层压板并开展单轴拉伸蠕变试验,获得了单向纤维复合材料主方向的蠕变本构模型参数。采用有限元方法并借助用户自定义材料子程序建立储运发射箱长期储存蠕变的数值分析模型,预测了堆码储存15年后底层发射箱的蠕变变形。以储存后的发射箱作为初始状态建立弹管耦合发射动力学仿真计算模型,进一步分析蠕变对火箭弹发射过程的影响。仿真结果表明:蠕变引起的定向器平行度和发射箱底面平面度的变化均小于技术指标规定值,定向器束的最大残余变形在三维空间内呈马鞍状分布,上、下两行中间位置定向器的变形最大,左、右两列中间位置定向器的变形最小。定向器蠕变变形使得弹管间隙减小,火箭弹在管内运动使弹管之间的动态接触碰撞力增大,离轨速度降低。     

基于矢量分配的组合导航容错联邦滤波算法

针对高动态环境下飞行器组合导航系统因不确定故障导致导航精度下降的问题,提出了一种基于矢量信息分配的容错联邦滤波算法。设计矢量形式的故障检测函数,对各观测量进行单独的故障程度划分,克服了将故障子系统所有观测量同时隔离的缺陷;根据观测量是否异常,重构时变量测噪声矩阵和信息分配矢量系数,对子滤波器的状态变量进行信息分配,在隔离故障子系统异常观测量的同时,最大限度地利用正确观测信息。仿真结果表明,采用该算法能够充分发挥各导航子系统的优势,极大提高了导航子系统信息利用率,具有较高的精确性和容错性。     

Robust adaptive UKF based on SVR for inertial based integrated navigation

Aiming at the problem that the traditional Unscented Kalman Filtering (UKF) algorithm can’t solve the problem that the measurement covariance matrix is unknown and the measured value contains outliers, this paper proposes a robust adaptive UKF algorithm based on Support Vector Regression (SVR). The algorithm combines the advantages of support vector regression with small samples, nonlinear learning ability and online estimation capability of adaptive algorithm based on innovation. Firstly, the SVR model is trained by using the innovation in the sliding window, and the new innovation is monitored. If the deviation between the estimated innovation and the measured innovation exceeds a given threshold, then measured innovation will be replaced by the predicted innovation, and then the processed innovation is used to calculate the measurement noise covariance matrix using the adaptive estimation algorithm. Simulation experiments and measured data experiments show that SVRUKF is significantly better than the traditional UKF, robust UKF and adaptive UKF algorithms for the case where the covariance matrix is unknown and the measured values have outliers.     

Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites

The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide (NaOH) on physical and dynamic mechanical analysis (DMA) viscoelastic properties of kenaf fibre filled natural rubber (NR)/thermoplastic polyurethane (TPU) composites. The treated kenaf fiber, NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine. The polymer composites were then fabricated using the hot press to form a sample board. The sample was cut and prepared and water absorption, density, thickness swelling and DMA tests were performed. As far as physical properties are concerned, composites with the highest NR amount of shows the best results, which indicates good fiber bonding adhesion. The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature.     

一起灭火器爆炸案的原因调查

全面调查和分析了某住宅公寓灭火器爆炸事故的事故原因及相关责任,得出造成灭火器爆炸的根本原因是灭火器所充装的ABC干粉存在严重质量问题的认定,并依据相关法律将该案件作为刑事案件移交公安部门。     

拟声修辞对英语语言音、意、形的辅助作用

拟声作为一种修辞格,主要有基本拟声和次要拟声两种形式,它常用于文学创作中,创造出所需要的音响效果,使人有身临其境之感,在语言的音韵,意像,形式上发挥着重要的修辞作用。     

运动液滴蒸发时传热传质过程的理论分析

对突然置入气体环境中的运动液滴的非稳态蒸发过程进行了传热传质过程的理论分析,建立了初始瞬间液滴非稳态蒸发的数学模型,并对模型进行数值求解.结果表明,在一定情况下,运动液滴突然置于气体环境中的初始瞬间,由于气液界面上与周围环境之间存在较大的浓度差,使得液滴在初始瞬间的蒸发速率很大,将会使气液界面的温度有所下降,这一温度的下降范围与液滴的初始温度、环境的初始温度以及液滴的运动速度有关.     

基于核主成分分析的高校科技创新能力评价研究

高校在国家创新体系中占有举足轻重的地位,高校科技创新能力评价研究对提高高校科技创新能力具有积极的意义.基于核主成分分析的评价方法能够有效去除高校科技创新能力评价指标体系中的废咝韵喙匦畔?从而取得较好的评价结果.以15所教育部直属高校科研统计数据为样本,利用核主成分分析法进行了高校科技创新能力评价的实证分析,并与主成分分析结果进行了比较,结果表明,核主成分分析能够取得更高的主特征值累积贡献率,从而产生更为合理的评价结果.     

Ambulance location for maximum survival

This article proposes new location models for emergency medical service stations. The models are generated by incorporating a survival function into existing covering models. A survival function is a monotonically decreasing function of the response time of an emergency medical service (EMS) vehicle to a patient that returns the probability of survival for the patient. The survival function allows for the calculation of tangible outcome measures—the expected number of survivors in case of cardiac arrests. The survival‐maximizing location models are better suited for EMS location than the covering models which do not adequately differentiate between consequences of different response times. We demonstrate empirically the superiority of the survival‐maximizing models using data from the Edmonton EMS system. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2008