一种自整角机信号发生器设计

自整角机信号发生器将输入的数字角度信号转化为模拟量,驱动自整角机旋转,广泛应用于控制系统中。国外的自整角机信号发生器产品进口周期长,并且进行技术封锁,国内产品转换精度较差,转换速度较慢。针对国内外自整角机信号发生器存在的问题,介绍了一种以单片机为控制和处理核心的能够将自整角机信号数字角量转化为模拟角度的信号发生器的设计方案,分析了如何用单片机及D/A芯片实现将数字角量信号转化为自整角机所需的三路模拟信号,改善了转换速度和精度的问题,提高了稳定性和抗干扰性等性能。     

基于虚拟仪器的可控转角信号源设计与实现

针对测控领域中可控转角信号复杂多变的特点,利用虚拟仪器技术设计并开发了可控转角信号源,该信号源包含控制式自整角机方式、力矩式自整角机方式和旋转变压器方式3个模块,能够根据需要生成高精度的控制式自整角机、力矩式自整角机和旋转变压器3种转角信号,满足现代工程测量的需要.     

自整角机／旋转变压器测角传感器的信息处理

浊角传感器自整角机（或称同步器）和旋转变压器（或称解算器）已广泛用于数控机床、机器人和军事装备的火控等控制系统中，在这些系统中除用于测角直接显示外，更多的是用于输入微处理机对输出轴角进行控制，为此需要将自整角机和旋转变压器输出的正、余弦交流信号变换成微处理机能接受数字信号；或将表征角度的数字信号变换成自整角机或旋转变压器能接受的正、余弦交流信号。下面简单介绍自整角机和旋转变压器测角控制过程的信息处     

交流力矩式自整角机仪表的微机控制方法

利用微机接口输出的直流电信号，经直流放大器放大后直接驱动交流力矩式自整角机仪表工作，是一种新方法。采用这种方法实现微机控制交流力矩式自整角机仪表工作，电路简单，工作可靠，经济实用。     

基于单片机的自整角机转角测量研究

介绍了一种基于单片机的自整角机转角测量方法,该方法省略了自整角机/数字转换器(SDC)和交流激磁电源,直接利用单片机进行激磁和采样来确定自整角机的转角,不仅硬件系统组成简单、满足测量精度,降低系统开发成本,而且,提高了系统的可靠性。本方法已经应用到航空仪表伺服控制系统中。     

自整角机工艺误差的修正方法

在系统阐述自整角机工作原理的基础上 ,详细论述了在航空炮塔随动系统中 ,如何利用现有的自整角机来减小随动系统的误差以及消除假协调 ,从而使随动系统满足技战术指标。     

航空发动机智能自整角机传感器的设计

根据航空发动机自整角机传感器的原理,提出一种基于DSP与CAN的智能自整角机传感器.设计了上电自检电路、热电偶信号处理电路、DSP与CAN总线接口电路以及电源电路.该传感器系统集成度高,测量和处理速度快.实验表明,该自整角机传感器测量误差小,测量精度高、实时性好,可应用于航空发动机全权限数字式电子控制(FADEC)系统中,具有重要的实用价值.     

航空发动机智能自整角机传感器的设计

根据航空发动机自整角机传感器的原理,提出一种基于DSP与CAN的智能自整角机传感器。设计了上电自检电路、热电偶信号处理电路、DSP与CAN总线接口电路以及电源电路。该传感器系统集成度高,测量和处理速度快。实验表明,该自整角机传感器测量误差小,测量精度高、实时性好,可应用于航空发动机全权限数字式电子控制(FADEC)系统中,具有重要的实用价值。     

也谈自整角机角度信号的数字转换

以数字表述方式提出一种自整角机的编码方法，具有普遍意义。     

一种基于CORDIC算法的自整角机信号解码研究

自整角机是一种用于角度测量的微型电机,其输出包含角度的模拟信号经过简单处理和A/D变换后再通过CORDI算法解码。CODIC算法具有精度灵活可调、运算速度快、硬件实现简单等优点;通过对CORDC算法角度及对自整角机输出信号的象限修正,设计了一种基于CORDIC算法流水线技术的自整角机解码算法,并以FPGA为平台进行模拟和仿真,验证其准确性及可行性。     

Load mapping for seamless interface between hydrodynamics and structural analyses

This paper addresses the problem of a seamless interface between hydrodynamics and structural analyses. A pressure distribution on a hydro model computed from seakeeping analysis needs to be transferred to a structural model for evaluating structural strength and its integrity. However, due to the differences in the computation and representation methods for both analyses, the load on the hydro model may not be correctly transferred to the structural model, leading to a different load distribution on the structural model and resulting in some unbalanced force and moment components. In this paper, a method is proposed to solve this problem. A pressure distribution on the hydro model is mapped on the structural model through projection, and force and moment imbalances on the structural model are eliminated through optimization of the nodal forces on the structural model. Moreover, a viscous force distribution along the center of each member of the hydro model is transferred to the nodal forces on the structural model based on the minimum distance measure with resolving any force and moment imbalance. Examples are presented to demonstrate the validity of the proposed method.     

Experimental studies on passive dynamic bipedal walking

Passive dynamic walking is a gait developed, partially or in whole, by the energy provided by gravity. The research on passive dynamic bipedal walking helps create an understanding of walking mechanics. Moreover, the experimental passive dynamic research provides a base to compare and validate computer simulation results. An improved kneed bipedal walking mechanism was designed and built to study the passive gait patterns. The first aim of this study is to determine the equivalency of testing a passive dynamic biped walker on a treadmill to testing on a ramp. Based on the small difference between the gait patterns measured on the two test platforms, testing on a treadmill was found equivalent to testing on a ramp. Gait measurements were then conducted on the treadmill to evaluate the effects of the treadmill inclination angle, mass distribution of the biped, and the length of flat feet on the gait pattern. Results show that most of these parameters had significant effects on the step length, step period and hip velocity of the passive walker. Our experimental results are also compared with previous experimental results.     

地铁站楼梯行人流交通特征的数据拟合分析

随着中国城市化水平的不断提高,行人在整个城市交通体系中的影响越来越大,越来越多的研究开始关注行人交通。但目前国内外对行人交通的研究都集中在水平步道上,尚没有对楼梯的行人流特征的研究,特别是缺少对大城市重要人流重要集散地的步行楼梯行人流特征的分析研究。通过对上海市赤峰路轻轨车站、上海人民广场地铁站和上海火车站地铁站等几个重要的行人集散地的楼梯行人流的特征调查,以定性分析为基础得到楼梯行人流的密度－速度、密度－流率的函数关系类型,并采用Matlab等软件进行函数拟合,得到换乘枢纽的行人流特征函数及楼梯行人流特征模型。为合理设置换乘枢纽内楼梯设施,提高楼梯的通行能力,更好组织行人流提供依据。     

Assessment of anti-slip devices from healthy individuals in different ages walking on slippery surfaces

The interest for effective preventive strategies for slips and falls is growing. Much remains to be done, however, to prevent slips and falls in the traffic environment. Using an appropriate anti-slip device may reduce the risk of slips and falls on different surfaces outdoors during winter. The aim of this study was to evaluate the best anti-slip devices of different designs in the Swedish market on a larger group of healthy individuals in different ages on five different slippery surfaces as a way to develop a standard method to test anti-slip devices. Three different designs of anti-slip devices: heel device, foot-blade device and whole-foot device were evaluated on ice surfaces uncovered or covered with gravel, sand, salt or snow. The evaluations were done according to subject's perceived walking safety and balance, videorecordings of walking postures and movements, time to take on and off each anti-slip device, advantages/disadvantages with each anti-slip device and a list of priorities for own use according to three criteria: safety, balance and appearance. The heel device was perceived to be the most safe on all five surfaces, followed by the toe device and the whole-foot device. The heel device was also perceived to be the one with the best walking balance on uncovered ice and on snow covered ice. There were some significant differences due to gender and age. Most subjects walked with a normal muscle function in the hip and knee when walking with or without an anti-slip device on all surfaces. The heel device was perceived as the most rapid one to take on and the toe device as the most rapid one to take off. All three devices were perceived as having a good foothold. The heel device was perceived to fit the shoe and to be stable at heel-strike. The toe device was easily portable and stable on uncovered ice. The whole-foot device was comfortable to walk with and safe on snow covered ice. The heel device had the highest priority according to walking safety, walking balance and choice for own use.     

PAC-Bayesian Compression Bounds on the Prediction Error of Learning Algorithms for Classification

We consider bounds on the prediction error of classification algorithms based on sample compression. We refine the notion of a compression scheme to distinguish permutation and repetition invariant and non-permutation and repetition invariant compression schemes leading to different prediction error bounds. Also, we extend known results on compression to the case of non-zero empirical risk.We provide bounds on the prediction error of classifiers returned by mistake-driven online learning algorithms by interpreting mistake bounds as bounds on the size of the respective compression scheme of the algorithm. This leads to a bound on the prediction error of perceptron solutions that depends on the margin a support vector machine would achieve on the same training sample.Furthermore, using the property of compression we derive bounds on the average prediction error of kernel classifiers in the PAC-Bayesian framework. These bounds assume a prior measure over the expansion coefficients in the data-dependent kernel expansion and bound the average prediction error uniformly over subsets of the space of expansion coefficients.Editor Shai Ben-David     

基于桥梁用户的多社交网络影响最大化

单社交网络影响最大化问题已经得到了学术界的广泛关注与研究,然而如今多社交网络之间呈现信息互通的趋势.多社交网络中存在的桥梁用户（Bridge User,BU）（即同时拥有多个社交网络账户的用户）,可将信息从一个社交网络分享至另外一个社交网络,信息传播不再局限于单个网络.本文针对多社交网络信息影响最大化进行了相关研究,分析了桥梁用户在多社交网络信息传播中的作用,提出了基于桥梁用户的多社交网络聚合算法,并在得到的聚合图上对多社交网络影响最大化问题进行求解.仿真实验对多社交网络影响最大化问题进行了求解,并证实了桥梁用户在多社交网络信息传播时的作用.     

启发式算法设计中的骨架分析与应用

骨架是指一个NP-难解问题实例的所有全局最优解的相同部分, 因其在启发式算法设计中的重要作用而成为该领域的研究热点. 本文对目前骨架及相关概念的研究成果进行了全面综述, 将骨架本身的研究工作归纳为三个层面: 理论基础层面主要考虑骨架与计算复杂性的关系问题; 应用基础层面主要考虑如何高效地获取骨架; 应用层面主要考虑如何利用骨架进行高效启发式算法设计. 在此基础上, 本文详细讨论了骨架研究亟待解决的难题, 并指出了解决这些问题的努力方向.     

The effects of organizational learning environment factors on e-learning acceptance

Workplace learning is an important means of employees’ continuous learning and professional development. E-learning is being recognized as an important supportive practice for learning at work. Current research on the success factors of e-learning in the workplace has emphasized on employees’ characteristics, technological attributes, and training design elements, with little attention to workplace contextual effects. The study aims to investigate the impacts of organizational learning environment factors, including managerial support, job support, and organizational support, on employees’ motivation to use a workplace e-learning system. A model was proposed based on the expectancy theory of training motivation and the social influences and facilitating conditions in technology acceptance models. The model was tested on sample data collected from mainland China using Structural Equation Modeling and Moderated Structural Equation Modeling. The results suggested that employees’ perceived managerial support and job support had a significant impact on their perceived usefulness of the e-learning system for individual learning, and that perceived organizational support had a significant influence on the perceived usefulness of the e-learning system for social learning. Perceived usefulness for individual learning was found to completely mediate the environmental influences on individuals’ motivation to use the system, while perceived usefulness for social learning made partial mediation in the effects of the environmental factors on intention to use. In addition, perceived job support was found to have moderating effects on the relationship between employees’ perceived usefulness of the e-learning system and their intention to use the system. Consistent with previous findings, employees’ perceptions about the usefulness of the e-learning system have significant effects on their intention to use the system in the work setting.     

对地面防空雷达网干扰能力的模糊综合评估研究

地面防空雷达网是防空系统的重要组成部分,对其实施有效干扰并对干扰效果进行评估,具有重要的现实意义。目前,结合具体的干扰方法对地面雷达网进行干扰效果定量评估的研究并不多,更多的是评估指标的选择确定和从微观的角度分析干扰效果。该文探讨了作战情况下,对地面防空雷达网进行干扰效果定量评估的方法,给出了一种模糊综合评估模型用于评估对地面防空雷达网的干扰能力,并指出该模型使用范围和条件。该文对研究评估对地面防空雷达网干扰能力具有一定的参考价值和指导意义。     

科学计算软件快速开发技术的研究

讨论了C＋＋语言与Matlab语言结合快速开发科学计算软件的优越性和可行性，Visual C 调用Matlab函数的几种方法，其中着重探讨Matlab函数在Visual C 中的编译技术以及如何在Visual C 中调用Matlab Shared M-DII，开发Windows平台独立可执行文件的技术。作为例程给出了Visual C 中开发小波分析软件的步骤和要点，给出了源代码，程序在Win2000系统下成功编译，并能独立运行在Win9x和Win2000操作系统上。