复杂场景中基于变块差分的运动目标检测

针对复杂场景中包含的摄像机扫描运动、随机抖动和目标运动,提出一种基于帧间可变块差分的运动目标检测算法.首先,利用全局特征点估计运动参数对帧间背景进行补偿,提取图像的全局特征点并匹配,以特征点集的最小位置误差和作为目标进行迭代,获取误差不大于0.5 pixel的全局运动参数,并精确补偿当前帧实现背景校正.然后,利用可变块...     

基于改进SIFT算子的动态障碍物检测方法

针对行车辅助驾驶系统在进行动态障碍物检测时遇到的背景复杂和实时性要求,提出了一种基于快速鲁棒的动态目标假设检测算法,算法首先采用相邻帧间特征点位置估计改进SIFT匹配算子,实现全局背景运动补偿参数快速估计,然后利用三帧差分法对图像处理后,通过改进背景方差估计,改善传统假设检验方法对图像边缘目标漏检的问题,进一步提高动态目标检测的准确性。实验表明,算法不仅保持了SIFT算子的优越性能,提高了参数估计精确性,而且极大地提高了特征配准和检测速度,满足系统的实时性要求。     

基于背景差和多层背景的目标持续检测研究

传统的目标检测方法只能检测出运动的前景目标,而进入监控场景后停止或移动缓慢的目标将被更新到背景里.文章提出了一种基于背景差和多层背景模型的前景目标持续检测方法,将背景分为动态背景和参考背景两层,采用改进的Surendra算法快速提取背景;曰标检测中,采用动态背景检测运动前景,通过动态背景与参考背景之差检测出静止前景.对...     

基于图像融合的运动目标检测与跟踪方法研究

从运动背景中检测与跟踪运动目标是计算机视觉研究领域的热点,根据帧差法的基本原理,提出了一种针对复杂背景的运动目标检测方法.首先通过设定阈值滤除序列图像中的噪声,然后对三帧算法进行改进,即利用序列中多帧图像融合运动信息,并确定参考区域,通过对原图像进行回扫描,最终提取出完整的运动目标轮廓.最后采用一种运动物体跟踪算法,实现了运动物体和静止物体的识别,克服了以往算法中的误检和空洞问题,实验结果表明,该方法能够满足实时性的要求.     

移动相机下基于三维背景估计的运动目标检测

室内环境中的运动目标检测是计算机视觉领域的研究热点,而移动相机造成的动态背景是运动目标检测的难点。本文提出一种基于同步定位与地图创建(ORB-SLAM)三维背景估计的运动目标检测算法,首先使用移动相机遍历整个室内环境,采用ORB-SLAM技术建立当前全局环境的三维背景特征点云模型;然后基于局部视频建立局部三维特征点云,根据定位信息将当前局部三维特征点云与环境三维背景特征点云进行嵌入,基于环境背景信息,采用三维均值漂移(3DMS)算法,对局部三维特征点云进行前景特征点提取;运用深度卷积神经网络,对提取的前景特征点所在候选区域进行运动目标确认。通过多个室内场景的实际实验进行验证,结果表明本文方法具有较高的运动目标检测准确率和召回率,提出的运动目标检测算法充分利用了三维背景信息,采用深度卷积神经网络进行确认,有效地改善了检测的准确性和鲁棒性。     

基于相位相关和差分相乘的动态背景下运动目标检测

本文提出一种基于相位相关和差分相乘的动态背景下运动目标检测方法。首先用相位相关算法配准由于摄像机运动导致的图像背景旋转、缩放和平移量,然后用连续四帧图像差分相乘的方法分割出运动目标的轮廓,最后用形态学图像处理方法填补运动目标中的小空洞,并滤除残留的孤立噪声点。经过对多个视频序列的试验验证,结果表明该方法具有良好的性能,它对于各种因素的影响,如光照变化、背景中树叶晃动等局部微小变化、背景配准误差等,都有很强的适应能力。     

动态特征块匹配的背景更新在运动检测的应用

为解决传统监控设备视场小、非智能等缺陷,结合全景成像技术和计算机视觉技术,建立无人环境下外来入侵自动检测系统,从而实现了全景监控视场下运动目标快速准确的检测及跟踪。该技术关键在于如何在复杂的动态背景下有效地提取运动目标,为此提出一种基于动态特征块匹配的自适应背景更新算法。在采用帧间差分与背景差分融合算法检测到目标的基础上,利用目标的矩信息进行跟踪,避免了全景视觉下颜色及轮廓特征缺失的弊端。根据目标的轮廓及位置提取特征块,将视频序列的每一帧图像与初始背景图像进行特征块区域的局部匹配,首先通过分析特征块图像的颜色特征,构建基于区间统计的RGB颜色直方图,提取颜色特征序列。然后通过计算序列相关性来判断该区域是否需要背景更新,从而降低对单个像素更新的冗余计算。实验表明,该更新算法具有较强的鲁棒性和可行性,能够有效提高监控系统的稳定性。     

基于色彩相似度的前景有效提取算法研究

提出一种将辅助背景滤波与色彩相似度检测相结合的前景有效提取算法。该算法首先运用背景差分构建辅助背景来描述环境噪声分布,并用辅助背景对疑似前景区域进行空域滤波,以增强算法对背景变化的适应能力;然后建立色彩相似度作为前景目标评价标准,进行前景目标检测;最后对检测结果进行形态学操作,得到比较完整的前景目标。多场景实验表明,该算法检测效果良好,具有较强的鲁棒性,对阴影和光照变化具有很好地抑制作用;同时实时性好,空间复杂度低。     

机载复杂场景下的低虚警红外目标检测

机载红外光电探测系统进行下视复杂场景目标探测时,地面虚警干扰源同弱小目标在空间分布上一致,传统算法会导致大量虚警。因此,提出一种基于运动目标特征的多维度特征关联检测算法。该算法首先对复杂场景进行特征点检测,引入基于相对速高比的跳帧机制,对经过图像配准的帧间图像进行差分处理检出候选目标。同时,结合基于核相关滤波的目标相似度方法进行多维多帧关联,进一步抑制虚警并确认目标。实验结果表明,在载机速高比大于30 mrad/s、系统帧时小于10 ms的机载环境下,该算法的平均检测率达到99.13%,虚警率降至10-5。该方法在多种机载复杂场景下得到验证,适合流水并行运算操作,满足工程实践需求。     

一种高效的背景重建与更新算法研究

为了实时准确地重建出背景,提出了一种基于帧间差分的背景重建算法.该算法等间隔采样视频帧.然后对视频序列进行帧间差分,对得到的差分图像分块处理,通过比较各子块的亮度与能量均值,将各帧中满足要求的子块进行组合,从而快速地重建出背景.当背景发生整体或局部变化时,该算法能够快速地检测出背景变化,并采用相应算法实时更新背景.实验结果表明,该算法能快速、准确地重建出背景,从而能够完整地提取场景中的运动目标.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.     

OPTIMIZATION METHOD ON IMPELLER MERIDIONAL CONTOUR AND 3D BLADE

An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics (CFD) analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories: the meridional contour design variables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network (ANN) techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller performance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.     

5083H111轧制铝合金的低周疲劳行为

在室温下对5083H111轧制铝合金板三个典型方向——轧制方向(RD方向)、与轧制方向成45°角方向(MD方向)、垂直于轧制方向(TD方向)的试样进行了单轴对称应变控制的低调疲劳试验,研究了不同方向试样的循环变形行为和疲劳寿命差异。结果表明:铝合金板在三个方向上都表现出了明显的循环硬化特性,即在恒定的应变幅下,三个方向的响应应力幅均随着循环次数的增加而增大,并且外加应变幅越大,响应应力幅也越大;三个方向的低周疲劳ε-Nf曲线差别不明显;三参数幂函数寿命模型可以很好地预测5083H111铝合金的低周疲劳寿命。