On multi-rigid-body system dynamics

A computer-oriented method for obtaining dynamical equations of motion for large mechanical systems or “chain systems” is presented. A chain system is defined as an arbitrarily assembled set of rigid bodies such that adjoining bodies have at least one common point and such that closed loops are not formed. The equations of motion are developed through the use of Lagrange's form of d'Alembert's principle.The method has been applied with human-body models and finite-segment cable models. The numan-body models are configured to simulate a crash-victim. Results obtained with several deceleration profiles agree very well with available experimental data.     

基于遥感图像水体识别与检测研究综述

地表水的勘测对于海岸线变化、环境保护、防灾减灾、水质检测都有重要的意义,借助遥感图像可以快速、反复、精确地获取到地表水的时空分布特征.文章调研国内外学者在遥感图像水体识别方向的研究成果,简述基于遥感技术的水体识别方法.其中,阈值法通过对水体和背景地物的光谱曲线进行分析,选取适合的阈值进行图像分割,操作简单便利,存在信噪...     

三维复杂地质体的布尔运算算法研究与实现

提出一种稳定快速的三维复杂地质体的布尔运算算法。该算法不需要跟踪交线,利用带拓扑信息的交边对实体区域进行分类,避免面在体内的判断,提高运算速度。算法在进行布尔运算前解决了数值计算误差引起的相关分类间的冲突,保证运算的稳定性。将该方法应用于蓝光矿山数字化平台系统,实践结果证明其适合数据分散、数据密集及带孔洞的实体,特别是大规模、奇异的三维复杂地质体。     

用通用MSI,LSI组件实现逻辑网络CAD

本文着重论述了用通用ＭＳＩ，ＬＳＩ组件进行计算机辅助逻辑设计的意义和实现方法，并例举了两个实例。论述了作者开发的应用软件－逻辑ＣＡＤ软件的突出特点，即；操作简便，输入方式符合日常惯例；数据结构２新颖，运算速度快；具有丰富的图形编辑功能。     

非单点证据体数据融合的Dempster组合规则适用性评价方法

针对待融合的证据体包含基本概率分配值相差较大的非单点证据时,基于pignistic距离的Dempster组合规则适用性评价方法判定结果存在模糊性甚至不准确的问题,提出了一种表示证据体之间关联性的改进pignistic距离,并将改进的pignistic距离与经典冲突系数相结合,提出了对Dempster组合规则适用性评价的新方法。在新方法中,定义了一种新的证据体冲突衡量系数用于判定Dempster规则的适用性。当经典冲突系数为0时,新系数与改进pignistic距离一致;当经典冲突系数不为0时,新系数与改进pignistic距离和经典冲突系数之和的平均值一致。算例分析的结果表明,与基于pignistic距离的Dempster规则适用性评价方法相比,新的基于改进pignistic距离的Dempster组合规则适用性评价方法有较好的适用性和合理性。     

一种基于众信度函数的相关证据合成方法

实际应用中,Dempster规则要求的证据独立性可能难以满足.在相关源证据已知的假设条件下,基于证据的众信度函数,提出一种相关证据合成方法. 该方法无需辨识独立证据的过程,可直接得到解析的合成结果,并且对相关源证据的形式没有要求.最后通过算例验证了所提出方法的有效性.     

布尔运算算法研究及其在地质体建模中的应用*

针对三维复杂地质体建模中存在的问题,提出了布尔运算算法。算法的实现采用四步法,即通过测试、求交、剖分和标记实现了区域划分,选择不同标记的三角面片即可得到不同的布尔运算结果。为解决数值计算误差对运算结果的影响,算法在求交运算前先进行逻辑判断,对共面求交的特殊情况进行处理。该方法已应用到蓝光矿山数字化平台系统中,能够实现任意复杂地质体的建模。     

Generalized Jeffrey’s rule of conditioning and evidence combining rule for a priori probabilistic knowledge in conditional evidence theory

In Bayesian probabilistic approach for uncertain reasoning, one basic assumption is that a priori knowledge about the uncertain variable is modeled by a probability distribution. When new evidence representable by a constant set is available, the Bayesian conditioning is used to update a priori knowledge. In the conventional D-S evidence theory, all bodies of evidence about the uncertain variable are imprecise and uncertain. All bodies of evidence are combined by so-called Dempster’s rule of combination to achieve a combined body of evidence without considering a priori knowledge. From our point of view, when identifying the true value of an uncertain variable, Bayesian approach and evidence theory can cooperate to deal with uncertain reasoning. Firstly all imprecise and uncertain bodies of evidence about the uncertain variable are fused to achieve a combined evidence based on a priori knowledge, then the a posteriori probability distribution is achieved from a priori probability distribution by conditioning on the combined evidence. In this paper we firstly deal with the knowledge updating problem where a priori knowledge is represented by a probability distribution and new evidence is represented by a random set. Then we review the conditional evidence theory which resolves the knowledge combining problem based on a priori probabilistic knowledge. Finally we discuss the close relationship between knowledge updating procedure and knowledge combining procedure presented in this paper. We show that a posteriori probability conditioned on fused body of evidence satisfies the Bayesian parallel combination rule.     

电力系统暂态稳定性的数值仿真研究

由于系统暂态失稳引发的大停电等事故频繁,所以加强对电力系统暂态稳定分析的研究具有重要意义。数值计算是系统仿真的重要手段,计算结果可以为系统的规划、设计、运行、分析、控制等提供依据。首先介绍了电力系统暂态稳定分析的主要方法,并利用时域法讨论了单机无穷大系统的暂态稳定性。其次,采用龙格库塔方法求解离散发电机转子的运动方程,得到了系统δ-t曲线。最后,运用上述方法计算实际问题,结果表明暂态稳定分析与初始运行方式、故障点位置、故障切除时间、故障后状态有关。因此,在实际生产中应注意结合上述特点减少事故发生。     

一种基于极大特征点的三维椎骨分割方法

椎骨的精确分割对于椎骨形态学研究和脊柱疾病的诊断和治疗有重要意义。通过 对正常人脊柱 CT 图序列的变化规律进行研究,提出了一种基于 CT 图像序列并利用椎骨面积 变化规律进行分割的椎骨分割算法。该方法通过对预先处理后的 CT 图像序列进行椎骨区域面 积统计,找出用于分割的显著极大特征点,并利用连续图像相似性筛选出椎骨实际分割点,最 后从序列中提取图像并进行三维重建。实验表明,该算法对正常人体腰椎和胸椎下部的椎骨 CT 图像序列有良好地分割效果,自动化程度较高。对脊柱形态学研究和矫正手术模拟有重要意义。       

基于分类优化的离散证据推理

离散信息在专家系统、模式识别、决策分析等领域普遍存在, 为了解决这类信息融合问题, 提出一种离散证据推理方法. 首先, 将每个离散证据拆分成一类单点值证据; 然后, 以冲突最小化为目标修正类内证据, 并采用证据推理进行组合; 最后, 以同样的方法对类间证据进行修正与组合. 所提出方法不仅可以解决离散证据的内外部冲突问题, 而且能够克服运算量过大的问题. 算例分析表明了所提出的方法是合理且有效的.

     

基于无线传感器网络技术的水质监测系统

随着人们对赖以生存的水环境的重视,水质实时在线监测系统需求迫切。基于对无线传感器网络技术的研究,以无线传感器网络为通讯手段,结合水质评价模型,设计了一个水质在线监测系统。实现对特定水域的实时监测,对提高水质保护和水资源合理利用具有一定的意义。     

On the axiomatic justification of Dempster's rule of combination

Within the theory of belief functions Dempster's rule of combination is of particular importance for the integration of different bodies of evidence. In this article a set of axioms is presented that uniquely determines this rule. As the axioms reflect just the intuitive idea of partially moveable evidence masses the presented results emphasize the unicity of Dempster's rule. © 1992 John Wiley & Sons. Inc.     

基于证据理论物联网安全态势感知方法研究

社会物联网技术迅速发展,安全问题日益严重,对简便易用的物联网安全态势感知方法进行了研究。针对当前物联网安全态势感知系统缺乏通用性、过分依赖专家知识的缺点,提出了一种基于改进D-S证据理论的物联网安全态势感知方法。利用模糊高斯隶属函数计算漏洞信息隶属度矩阵,归一化后作为证据分布矩阵;利用改进Topsis方法衡量证据可信度,聚合两两证据间的局部可信度,根据态势评估场景改进期望正负解向量,充分抑制冲突性证据可信度,提高相互支持证据间可信度,利用加权平均方法进行漏洞信息融合得到态势评估结果;基于时间因子折扣和高危漏洞比例折扣证据理论融合形成态势感知结果,利用时间因子聚合多个态势评估数据,根据时间尺度对不同时刻的态势评估证据进行折扣,越接近当前时刻的证据折扣度越小,反之越大。同时,综合考虑不同时刻物联网漏洞信息,利用高危漏洞比例信息进行自适应动态加权,把不同时刻的高危信息折扣入识别框架,系统的危险变化信息集中体现在证据融合过程中。经过实验表明,在不同数量证据体融合和4种常见冲突证据融合中,改进Topsis方法对可信命题的融合概率更高;在态势评估方面,准确评估当前系统危险程度;在态势感知方面,折扣...     

Real ideal: Investigating how ideal and hyper-ideal video game bodies affect men and women

Media commonly feature imagery that celebrates idealized bodies and researchers have observed the adverse effects of such depictions. Although video games commonly feature idealized bodies, experimental work investigating the effects of game characters on body image disturbance remains underrepresented. This trend is surprising as the preponderance of hyper-muscular male and hyper-sexualized female characters speaks to the heteronormative, masculine fantasies often given prominence in game content. Using social comparison theory, the current work investigated how ideal and hyper-ideal video game bodies affected women's (study 1) and men's (study 2) body image dissatisfaction. The study also compared these outcomes to a non-exposure control condition. Generally, the data provided evidence that hyper-idealized game characters negatively affected men but positively affected women.     

Position‐based rigid‐body dynamics

We propose a position‐based approach for large‐scale simulations of rigid bodies at interactive frame rates. Our method solves positional constraints between rigid bodies and can therefore be seamlessly integrated into other position‐based methods. Interaction of particles and rigid bodies through common constraints enables two‐way coupling with deformables. The method exhibits exceptional performance and stability while being user controllable and easy to implement. Various results demonstrate the practicability of our method for the resolution of collisions, contacts, stacking and joint constraints. Copyright © 2014 John Wiley & Sons, Ltd.     

Sensor dynamic reliability evaluation based on evidence theory and intuitionistic fuzzy sets

This paper presents a new method for sensor dynamic reliability evaluation based on evidence theory and intuitionistic fuzzy sets when the prior knowledge is unknown. The dynamic reliability of sensors is evaluated based on supporting degree between basic probability assignments (BPAs) provided by sensors. First, the concept of asymmetric supporting degree is proposed. By transforming BPAs to intuitionistic fuzzy sets, supporting degree between BPAs is calculated based on intuitionistic fuzzy operations and similarity measure. Then the relationship between dynamic reliability and supporting degree is analyzed. The process of dynamic reliability evaluation is proposed. Finally, the proposed dynamic reliability evaluation is applied to evidence combination. A new evidence combination rule is proposed based on evidence discounting operation and Dempster’s rule. Comparative analysis on the performance of the proposed reliability evaluation method and evidence combination rule is carried out based on numerical examples. The proposed method for data fusion is also applied in target recognition to show its feasibility and validity.     

直方图反向投影多目标检测优化算法

针对目标检测中图像背景信息复杂以及反向投影方法目标颜色类型单一的问题,提出了一种改进的直方图反向投影目标检测优化算法．在建立多个目标模型弥补一般反向投影方法不能同时检测含有不同颜色信息目标这一不足的同时,通过对目标概率图像进行一系列优化处理以减小复杂背景对目标检测的干扰．实验结果表明,该算法在满足对视频图像实时处理要求的同时可准确检测目标位置,且检测效果及计算效率优于传统反向投影算法及其他方法．     

面向对象多特征融合的水域岸线目标变化检测

为认真落实河长制"清四乱"等专项行动,量化水域岸线监管测评工作,以岸线码头为目标,研究一种基于面向对象思想多特征融合的水域岸线目标变化检测方法。针对多时相高分辨率遥感影像,利用面向对象多尺度分割原理将具有空间连续性的同类区域划分为目标对象,提取目标对象的光谱、纹理及几何结构组成特征矩阵,并利用高斯径向基核函数支持向量机(RBF-SVM)进行分类;计算变化矢量差值,并与人工判读数据对比分析得到目标变化检测结果。实验结果表明,该研究应用于水域岸线上目标的变化检测中效果明显,RBFSVM分类误差影响最终目标变化检测的正确率,可为实现河湖水域岸线长效管护提供技术支撑。     

基于证据异常度的水下多源信息预处理方法

Dempster-Shafer证据理论在水下多源目标识别领域有着广泛而重要的应用, 但经典的证据理论在融合高度冲突的证据时往往会导致一些反常理的结果, 如Zadeh冲突悖论;针对这一问题,综合考虑证据体之间的冲突程度和支持程度,提出一种证据异常度的概念并对原始证据集进行异常检测,基于检测结果对原始证据体进行权重分配,引入全集项,修正证据源;在保持Dempster组合规则不变的前提下,进行有效的证据预处理,实验仿真结果验证了算法的有效性;证明对证据体进行有效的修正,可以改进经典证据理论的缺点,达到更好的融合结果。