雷达低仰角偏轴跟踪测量偏差补偿算法的改进研究

由于多径回波信号的干扰,严重影响了单脉冲测角体制雷达对低仰角目标俯仰角的测量,并使其对低仰角目标俯仰角的闭环跟踪测量实现极为困难;通过对多路径反射环境模型分析,同时考虑镜面反射和漫反射的干扰,得出了单脉冲雷达低仰角跟踪时俯仰角测量误差的产生原因,用传统的多目标分辨算法(C~2算法)弥补偏差补偿算法在目标飞行高度很低(5 m以下)时和距离近时补偿效果较差的不足;在给定的测量环境下对不同高度目标进行了仿真,得到良好的仿真结果,表明两种算法结合使用,可较大地提高低仰角目标偏轴跟踪俯仰角的测量精度。     

基于数据优先级的雷达目标跟踪偏差补偿方法

传统雷达目标跟踪偏差补偿方法雷达跟踪目标偏差补偿的精准程度较低,导致研究成果可靠性及稳定性较差。为了解决上述问题,基于数据优先级提出一种雷达目标跟踪偏差补偿方法,利用雷达极化测量目标信号,并建立三维空间坐标,引导操作数据,通过对相位控制偏差的校准操作实现对数据目标的精准测量,提升系统检验的准确性,根据数据优先级原则,对极化脉冲进行角度测量,选取适宜测量方案,设置雷达目标方向图,进行雷达目标超分辨成像,加强实验研究力度,综合考虑优化信息与操作条件,实现对雷达目标跟踪偏差补偿方法的研究。实验结果表明,基于数据优先级的雷达目标跟踪偏差补偿方法具备较高的雷达跟踪目标偏差补偿的精准程度,研究可靠性较高,稳定性有了显著提升。     

改进的IMU传感器安装误差正交补偿方法

针对传统的正交补偿方法难以保证惯性测量单元具有较高的正交补偿精度的问题,提出了一种改进的适用于大角度和小角度安装误差角情形的正交补偿方法,该方法分别建立三轴加速度计和三轴光纤陀螺传感器的安装误差方程,对惯性测量单元进行速率标定和多位置静态标定,并利用最小二乘法求解惯性测量单元的安装误差方程参数.仿真和实验结果表明:该方法较传统的正交补偿方法具有较高的正交补偿精度和传感器标定精度,且回避了静态标定时在较大安装误差角下利用转位机构获得零偏存在较大误差的问题,大大地提高了标定效率.     

强海杂波背景下雷达低仰角跟踪技术研究

海杂波抑制和低仰角跟踪是雷达系统中需要解决的关键技术难题,需要对雷达系统进行针对性设计。某跟踪测量雷达通过综合运用时间灵敏度控制、动目标显示与检测、双门限检测等海杂波抑制手段和自适应偏轴跟踪、频率分集、雷遥协同等低仰角跟踪技术,在对掠海目标跟踪过程中取得了理想的跟踪效果,测量精度达到了设计要求。     

被动相控阵雷达自适应调度算法研究

研究被动相控阵资源优化调度.相控阵雷达实现目标跟踪,精度和实时性是主要的指标.针对现有的主动相控阵资源调度不能很好地解决被动环境下搜索截获概率低,跟踪精度差的问题,提出一种被动相控阵雷达自适应调度算法(以下简称为被动自适应调度算法).算法根据被动截获、跟踪的特点,设计被动自适应调度算法的实现框架,重点研究了被动自适应调度的任务参数自适应生成、任务优先级评估及调度自适应执行等算法过程,并给出了被动自适应调度算法性能评估指标.仿真结果表明,该算法能优化安排被动相控阵雷达时、空、频等资源,缩短目标发现时间,保证跟踪稳定性.     

二维滑窗数字跟踪

本文提出一种处理全景雷达回波图象的二维滑窗检测原理与方法,达到了边扫描边跟踪的目的。这种工作方式既能大大提高全景雷达的测量精度,又能有效地跟踪多个目标。     

相控阵雷达系统功能仿真及应用

在国土防空预警网优化问题的研究中,相控阵雷达具有频率捷变等特点和多目标跟踪能力,是构成国土防空预警网的重要组成部分.以雷达组网、组网雷达资源管理及相关算法测试为背景,嵌入到雷达组网仿真平台中并获得实测数据,提供了一种相控阵雷达功能仿真方法,重点讨论了波位编排、目标检测和相控阵雷达的任务调度算法等模块的实现.最后仿真系统对三个普通目标以及一个隐身目标在雷达扫描空域的搜索、验证、跟踪、失跟等雷达事件进行了仿真结果分析,验证了相控阵雷达系统和相关算法的有效性.     

回转轴运动精度的干涉测量与误差补偿分析

采用激光干涉仪检测混联数控机床回转轴的运动精度,达到对其综合评价的目的,为机床的运动精度误差补偿做准备.对雷尼绍激光干涉仪的结构和角度测量原理进行了详细探讨,分析了干涉仪在回转轴运动精度测量中的主要影响因素和误差诱因;作出了角度测量中正弦近似误差特性曲线,并提出了该测量误差的数学模型;讨论了激光波长补偿的机理,提出了一种通用、简便易行的回转轴角位移精度检测方法.     

基于补偿卡尔曼滤波的姿态估计算法实现

九轴的姿态测量单元包括加速度计、磁力计和陀螺仪,它采用微机电加工工艺,价格低廉但精度较差.为了获得更好的滤波稳定性和估计精度,基于补偿卡尔曼滤波原理,讨论了姿态估计算法的实现.具体过程如下:基于补偿卡尔曼滤波原理,讨论九轴测量信息的融合方法;利用加速度计和磁力计估算姿态初始值;使用手动转台实现静态标定,纠正零偏;使用高精度陀螺仪STIM210实现动态标定,设置滤波系数.结果表明,估计算法具有良好性能.     

六轴工业机器人在线误差补偿方法的研究

提出一种机器人动态误差在线补偿方法,用以提高机器人的轨迹精度。在机器人参数误差得到离线补偿之后,基于ANFIS构建自适应模糊神经网络轨迹控制器,建立在线补偿系统控制模型,通过ADAMS与Matlab的协同仿真对系统仿真分析;仿真结果验证了所提出方法的可行性。在自主研发制造的六轴工业机器人的平台上,借助于API激光跟踪仪对机器人末端跟踪测量,进行实验分析;实验结果验证了该方法的有效性。     

ARCADE — An architecture for CAD in electronics

Ever since the introduction of computers in development and engineering departments, design activities have been supported by computer methods in a growing number of design functions, in the interest of reducing development time and cost, and increasing the quality of the products. Computer Aided Design (CAD) — a generic term for these computerized tools — is recognized as a method for drastically reducing the development time of industrial products.CAD methods are currently being used during each of the various phases in the development activity. The introduction of these CAD tools for the various stages in the development cycle, however, was to a large extent effected in isolation, i.e. not as a “subset” of an overall concept. Lack of such a concept, with its inherent disciplines and compatibility aspects, has given rise to sub-optimal efficiency and effectivity. To remedy this situation, a generalized architecture for CAD has been developed. This architecture drastically reduced the large variety if input methods, combines all product data in one well-structured product file, supports all necessary design functions, assures the proper generation of technical documents, and above all, facilitates maximum efficiency by integrating the processes for various stages in the development cycle.The essentials of ARCADE will be described in this article, together with how the system is designed.The “ARCADE” way and method of working in an organization in which development, engineering, manufacturing, logistic and documentation departments are concerned with technical automation issues will, as such, be discussed.Benefits will, of course, also be elucidated.     

The dark side of the Internet: Attacks,costs and responses

The Internet and Web technologies have originally been developed assuming an ideal world where all users are honorable. However, the dark side has emerged and bedeviled the world. This includes spam, malware, hacking, phishing, denial of service attacks, click fraud, invasion of privacy, defamation, frauds, violation of digital property rights, etc. The responses to the dark side of the Internet have included technologies, legislation, law enforcement, litigation, public awareness efforts, etc. In this paper, we explore and provide taxonomies of the causes and costs of the attacks, and types of responses to the attacks.     

Interface as Exordium: The Rhetoric of Interactivity

In this article, I outline how the interface of new media functions rhetorically as an exordium to engage users and to dispose them to persuasion. The modular, networked, and interactive nature of new media requires an interface: a central place of interaction for the technological, human, social, and cultural aspects of new media. I propose that the interface functions rhetorically through three modes of interactivity, including multi-directionality, manipulability, and presence. By understanding these modes of interactivity and how they function to create various degrees of interaction and engagement, we can begin to develop the analytic tools needed to increase critical awareness of the interface. A rhetorical understanding of the interface enables us and our students to see that the shape and design of the interface is not natural and inevitable. The design of the interface is a design of human experience and, as such, the interface becomes a locus of power. The modes of interactivity it deploys are capable of enabling empowerment and enacting rhetorical patterns of control.     

Inter-digit co-ordination and object-digit interaction when holding an object with five digits

The current study investigated inter-digit co-ordination and object-digit interaction during sustained object holding tasks by using five, six-component force/torque sensors. The sum of the individual finger normal forces and the thumb normal force showed a parallel variation with a mean median correlation coefficient of 0.941. The normal force traces demonstrated the lowest coefficient of variation (about 9% as averaged across digits) as compared with other force/torque traces. The sum for the variances of the normal forces of the index, middle, ring, and little fingers was about 50% of the variance of the summed normal force of the four fingers. Of the five digits, the thumb, index, middle, ring and little fingers accounted for 50.0, 15.4, 14.6, 11.7 and 7.3% of the total normal force; and 39.4, 9.9, 19.3, 14.0 and 17.5% of the total vertical shear force (i.e. the load), respectively. The ratios of the normal force to the resultant shear force were 2.6, 4.5, 1.8, 2.2 and 1.3 for the thumb, index, middle, ring and little finger, respectively. The centre of pressure migration area of a single digit at the object-digit surface during object holding ranged from 0.30 to 1.21 mm². The current study reveals a number of detailed object-digit mechanics and multiple digits co-ordination principle. The results of this study may help to improve ergonomic designs that involve the usage of multiple digits.     

当前人工智能技术创新特征和演进趋势

近年来，全球人工智能发展进入新一轮技术创新活跃期，新的理论、模型、算法快速迭代。本文从模型算法、软硬件实现以及技术形态等角度分析了当前全球人工智能技术的主要特征，总结了国内外人工智能前沿研究的一些创新热点和新动向，并从基础理论突破、底层计算模式创新、模型算法演进等方面，展望和探讨了未来人工智能技术进一步突破的几个可能趋势。     

仿生机器人运动步态控制:强化学习方法综述

仿生机器人是一类典型的多关节非线性欠驱动系统，其步态控制是一个非常具有挑战性的问题。对于该问题，传统的控制和规划方法需要针对具体的运动任务进行专门设计，需要耗费大量时间和精力，而且所设计出来的控制器往往没有通用性。基于数据驱动的强化学习方法能对不同的任务进行自主学习，且对不同的机器人和运动任务具有良好的通用性。因此，近年来这种基于强化学习的方法在仿生机器人运动步态控制方面获得了不少应用。针对这方面的研究，本文从问题形式化、策略表示方法和策略学习方法3个方面对现有的研究情况进行了分析和总结，总结了强化学习应用于仿生机器人步态控制中尚待解决的问题，并指出了后续的发展方向。     

基于Bully算法的Redis集群选举方案优化

随着互联网的迅速发展,用户从系统获取的信息越来越多,访问系统的频率也在迅速增加。当大量客户端访问系统时,请求的响应时间也会大幅增加,传统关系型数据库已经无法满足用户的需求,而内存数据库在保证系统稳定的前提下,改善了用户体验,并得到了越来越广泛的应用。作为NoSQL内存数据库,Redis支持很多数据类型,适用于多种情况下的缓存与存储需求。文中主要介绍Redis集群,它是Redis的分布式实现,支持主从复制,也具有一定的容错性和线性可扩展性,当前使用Redis集群的网站有新浪微博、github等。虽然 Redis集群 应用广泛,但目前它在节点下线后会出现恢复时间长的现象,这与现有Redis集群的选举算法有关,即与Raft算法的实现有关。分析了Redis集群的可靠性,并优化了集群的选举算法。测试结果显示,在单个主节点下线50s内,优化后的集群都能成功恢复,比社区版本的集群提高了40%。     

新闻推荐算法可信评价研究

随着AI、5G、AR/VR等新技术的快速发展,内容类应用如电子商务、社交网络、短视频等层出不穷,导致信息过载问题日益严重。人工智能技术的发展推动了智能算法的爆炸式运用,作为智能算法的一种,推荐算法在大数据、应用场景和计算力的推动下,通过信息过滤技术,为用户提供适应兴趣及行为的个性化及高质量的推荐服务,逐步提高了用户的使用体验、内容分发效率,在一定程度上缓解了信息过载的问题。但推荐算法的潜在偏见、黑盒化特性及内容分发方式也逐渐带来了决策结果不公平性、不可解释性,信息茧房、侵犯用户隐私等安全挑战。如何提高推荐算法的可解释性、公平性、可信程度等越来越受到国内外政府监管部门、产业及学术界的重点关注,推荐系统和推荐算法也由此从发展期进入管制期。为此,本文针对新闻推荐领域,分析推荐算法的稿件画像、用户画像、推荐推送、反馈干预和人工复审等关键要素,围绕推荐算法生态的参与者,如内容生产者、受众、算法模型、新闻平台,从公平性、可解释性和抗抵赖性三个方面提出了一种新闻推荐算法可信评价体系,并进行定量或定性分析。公平性、可解释性和抗抵赖性是正相关关系,当公平性和抗抵赖性越强、可解释程度越高,新闻推荐算法的可信度越高。希望弥补新闻推荐算法领域的可信研究的空白,建立可信推荐算法生态,加速安全推荐系统的建立和推广,同时为智能算法可信研究提供参考,为智能算法的监管和治理提供思路。     

Resin下CMP的开发

针对Resin下的应用,详细地阐述了Resin-CMP的开发、部署,以及调用的全部过程,并系统地阐述了多种关系的映射、管理,以及如何快速生成Resin-CMP。应用EJB、JNDI、CMR、ANT、EJB-QL、XDoelet等J2EE关键技术,充分体现了J2EE在开发分布式应用系统中的优势。     

Large area mapping of southwestern forest crown cover, canopy height, and biomass using the NASA Multiangle Imaging Spectro-Radiometer

A rapid canopy reflectance model inversion experiment was performed using multi-angle reflectance data from the NASA Multi-angle Imaging Spectro-Radiometer (MISR) on the Earth Observing System Terra satellite, with the goal of obtaining measures of forest fractional crown cover, mean canopy height, and aboveground woody biomass for large parts of south-eastern Arizona and southern New Mexico (> 200,000 km²). MISR red band bidirectional reflectance estimates in nine views mapped to a 250 m grid were used to adjust the Simple Geometric-optical Model (SGM). The soil-understory background signal was partly decoupled a priori by developing regression relationships with the nadir camera blue, green, and near-infrared reflectance data and the isotropic, geometric, and volume scattering kernel weights of the LiSparse–RossThin kernel-driven bidirectional reflectance distribution function (BRDF) model adjusted against MISR red band data. The SGM's mean crown radius and crown shape parameters were adjusted using the Praxis optimization algorithm, allowing retrieval of fractional crown cover and mean canopy height, and estimation of aboveground woody biomass by linear rescaling of the dot product of cover and height. Retrieved distributions of crown cover, mean canopy height, and aboveground woody biomass for forested areas showed good matches with maps from the United States Department of Agriculture (USDA) Forest Service, with R² values of 0.78, 0.69, and 0.81, and absolute mean errors of 0.10, 2.2 m, and 4.5 tons acre^- 1 (10.1 Mg ha^- 1), respectively, after filtering for high root mean square error (RMSE) on model fitting, the effects of topographic shading, and the removal of a small number of outliers. This is the first use of data from the MISR instrument to produce maps of crown cover, canopy height, and woody biomass over a large area by seeking to exploit the structural effects of canopies reflected in the observed anisotropy patterns in these explicitly multiangle data.