基于最小字符投影的车牌图像错切校正方法

为解决车牌图像倾斜对字符分割与识别带来的不利影响,提出一种基于字符投影的车牌图像错切校正方法.对旋转后的车牌字符区域向水平坐标上投影,利用最小投影距离获取水平错切角,采用二维几何变换对图像进行校正.试验结果表明,该方法不依赖车牌边框特征,抗干扰性强,具有较高的鲁棒性.     

基于字符投影最小距离的车牌校正方法

提出一种利用字符投影距离进行车牌校正的方法。根据伴生与互补颜色特征提取车牌中的字符区域,将车牌旋转计算字符区域在垂直坐标轴上的投影,利用投影的最小距离获取垂直倾斜角度。将车牌水平错切计算字符区域在水平方向投影,利用投影最小距离获得水平错切角度,采用双线性插值对图像进行校正。该方法不依赖车牌边框特征,抗干扰性强。实测车牌图像试验证明,该方法具有较高的鲁棒性和工程实用性。     

利用ActiveX Automation在AutoCAD中自动切取地质剖面

为进一步提高在AutoCAD中的工程地质图上进行切取剖面图的工作效率,本文从原理和细节上探讨了通过Delphi语言利用ActiveX Automation技术来操纵AutoCAD,从而实现自动切取地质剖面的技术方法。     

加速透视投影体绘制技术研究

针对可视化中透视体绘制计算量大、耗时较长的不利因素,算法将三维体数据集按照三种主要的观察方向(X,Y,Z)抽取出切片数据,对切片数据进行错切操作,设立一个与切片平行的中间图像平面;在绘制中间图像时使用图形硬件所提供的纹理混和功能;最终图像经过中间图像的变形而得到,从而使绘制速度得到了较大提高。     

基于AutoCAD的CAD模型直接切层方法研究

本文在AutoCAD环境下,利用其内嵌的AutoLISP语言开发出一种等厚度直接切层方法,并对此切层方法进行了实验验证。以该切层方法得到的截面图形为动态掩膜,利用面曝光快速成形系统成功制作出了三维实体原形,结果表明该直接切层方法适用于面曝光快速成形系统。     

基于边界体素的Shear-warp Splatting体绘制算法

将错切空间中体素投影到中间图像平面的过程中,要影响到该体素对应象素周围的其它象素,该文重新设计了计算对应象素权值的简单方法,使结果图像的质量与最近邻点投影方法相比有较大提高。为了加速体绘制,方法是先找出切片数据集中包围同种物质的边界体素,由于被这一边界所包围的体素有相同的属性,可以一次投影这一体素块,从而提高了绘制速度。文章还设计了低、中、高三种不同分辨率的投影模式,可根据需要选择一种。在数据结构上,使用了索引和游程编码方式,缩减了存储容量并加快了查找边界体素的速度。     

基于局部投影方差的快速车牌校正方法

车牌倾斜与错切校正作为车牌识别的重要环节,虽已提出不少方法,但仍存在准确度低、效率低等不足。鉴于现有方法的不足提出一种高效的车牌倾斜与错切校正方法。首先,根据车牌图像的投影方差存在着明显的局部性规律,提取车牌的局部特征图像用于角度检测。并提出一种基于坐标旋转的最大投影方差获取方法,快速得到车牌水平倾斜角度和垂直错切角度。此外,针对字符本身的结构对于垂直错切角度检测的影响,提出相应的解决策略。最终使用3000张情况各异的车牌进行实验。实验结果表明,在正确率比现有传统方法略高的情况下,算法效率也得到大幅提升。     

CAN协议的错帧漏检率改进

过去对CAN的漏检错帧概率的研究很有限,数据的获得主要依靠大量的仿真测试.由于要仿真的量太大,实际上仿真的仍然是极小的样本,所以得到的漏检错帧概率可信性不足.本文介绍了漏检实例的构造方法,从而进行漏检错帧概率下限的分析计算.得到的CAN协议的漏检错帧概率远大于以前的结论,因此对CAN的应用有巨大的冲击.由于已有大量应用...     

单视点生成体视图的方法研究

简述了体视投影的原理,根据透视变换矩阵推出了体视投影的变换矩阵,研究了基于单视点透视功能生成体视投影的方法,即将原对象物体沿x错切和平移变换后,即可由当前视点（右视点）得到第二视点（左视点）的投影图,并用射影几何从理论上证明了算法的正确性。用AutoCAD生成算法的体视投影,结果表明方法正确。     

硬件中冗余探错研究

本文深入分析和总结了计算机系统中针对硬件错误的传统冗余探错技术的各种思想,对于解决不同问题的各类方法进行了剖析,给出了一些研究热点上最新的研究进展与技术,最后在深入研究硬件中冗余探错方法的基础上提出了目前已有技术还存在的一些亟待解决的关键问题,对于进一步提高硬件可靠性打下了坚实的基础.     

Motion and stereoscopic tilt perception

Abstract— Stereoscopic perception of tilt about a vertical or horizontal axis is influenced by size and shear disparities, respectively. Other researchers have reported that, under certain conditions, stereoscopic perception deficits occur when the dots in a random-dot stereogram move at a velocity that produces optokinetic nystagmus. Here we examine how size disparity and shear disparity affect stereoscopic tilt perception under various motion conditions. We hypothesized that visual stimulus motion may interact with these disparities to affect tilt perception. Our results indicate that shear disparity and size disparity effects under static conditions are maintained under motion conditions. A possible explanation for the conflict between the current and previous results is discussed, as are implications for binocular head-mounted display applications.     

机载前视风切变雷达AMTI杂波抑制技术

在机载前视风切变雷达的低空风切变探测中,所面临的不仅仅是复杂的运动杂波,而且飞机高度低(300米左右),杂波功率相当大,信杂比可达-25dB左右。用传统的杂波抑制方法无法有效地抑制杂波,提出一种基于功率输出最小准则的自适应MTI技术。根据准则技术可以自适应地调整滤波器的加权系数,从而保证滤波器输出功率最小,使输出的信杂比最大,达到充分抑制强杂波的目的。计算机仿真结果表明AMTI杂波抑制技术在甚低信杂比(-25dB)情况下具有较好的杂波抑制能力,可以主动跟踪主瓣杂波的多普勒频率,能够很好的满足机载前视风切变雷达杂波抑制的需求,同时方法结构简单,便于工程实现。     

Intelligent design of shear wall layout based on graph neural networks

Structural scheme design of shear wall structures is important because it is the first stage that guides the project along its entire structural design process and significantly impacts the subsequent design stages. Design methods for shear wall layouts based on deep generative algorithms have been proposed and achieved some success. However, current generative algorithms rely on pixel images to design shear wall layouts, which have many model parameters and require intensive calculations. Moreover, it is challenging to use pixel image-based methods to reflect the topological characteristics of structures and connect them with the subsequent design stages. The above defects can be effectively solved by representing a shear wall structure in graph data form and adopting graph neural networks (GNNs), which have a robust topological-characteristic-extraction capability. However, there is no existing research using GNN methods in the design of shear wall structures owing to the lack of graph representation methods and high-quality structural graph data for shear walls. Therefore, this study develops an intelligent design method for shear wall layouts based on GNNs. Two graph representation methods for a shear wall structure—graph edge representation and graph node representation—are examined. A data augmentation method for shear wall structures in graph data form is established to enhance the universality of the GNN performance. An evaluation method for both graph representation methods is developed. Case studies show that the shear wall layout designed using the established GNN method is highly similar to the design by experienced engineers.     

基于模糊C均值的低空风切变预警算法

针对新一代多普勒天气雷达CINRAD在径向或切向检测风切变时容易丢失小切变的问题,提出了一种基于模糊C均值（FCM）的低空风切变预警算法用于阵风锋和龙卷风引起的风切变识别中。该算法的核心思想是运用8邻域系统,根据风速梯度识别不同程度切变,从而实现高切变及低切变预警。首先,采用全变分（TV）模型对雷达速度基数据进行去噪,同时保持速度基数据的细节特征;其次,采用每个速度基数据及其8邻域系统分别对应的速度值依次与4个方向模板卷积,获取4个方位速度梯度值;然后,采用FCM算法将梯度值分为高低两类,实现不同强度的风切变预警。采用武汉暴雨研究所提供的实测基数据进行测试和验证,能较为准确地识别出小切变。实验结果表明,该算法检测出来的风切变在定位精度和边缘识别两个方面均优于基于径向或切向的风切变识别算法,这对判断风切变的位置和强度以及分析不同天气引起的风切变具有重要指导意义。     

Adaptive modelling of plates in bending and shear

As an alternative to a direct finite element approximation of the Reissner–Mindlin plate equations we propose an adaptive modeling starting with a finite element solution according to the Germain–Kirchhofff equation and in an adaptive manner adding shear deformations calculated from the Germain–Kirchhoff shear forces. The system matrix need not be changed, so the extra cost, compared to the first solution, can be kept small.     

Nonlinear surface waves interacting with a linear shear current

To describe the evolution of fully nonlinear surface gravity waves in a linear shear current, a closed system of exact evolution equations for the free surface elevation and the free surface velocity potential is derived using a conformal mapping technique. Traveling wave solutions of the system are obtained numerically and it is found that the maximum wave amplitude for a positive shear current is much smaller than that in the absence of any shear while the opposite is true for a negative shear current. The new evolution equations are also solved numerically using a pseudo-spectral method to study the Benjamin–Feir instability of a modulated wave train in both positive and negative shear currents. With a fixed wave slope, compared with the irrotational case, the envelope of the modulated wave train grows faster in a positive shear current and slower in a negative shear current.     

微管道内的剪应力传感器

制作了一个微管道内的剪应力传感器,该传感器通过热传递的原理工作.采用硅微加工技术制作微管道,在玻璃上通过溅射方法形成钛铂合金热膜,最后将两者键合封装,形成埋置了热膜的封闭微管道.测量了热膜的电阻温度系数,确定了热膜处于不同输入功率下的过热比.对该剪应力传感器进行了方波实验,确定其工作在不同过热比下的时间常数.对传感器进行实验标定,得到不同进出口压差下,微管道内的壁面剪应力大小.     

高层建筑结构CAD中剪力墙节点几何归并的点阵表示？…

对高层建筑结构ＣＡＤ系统中剪力墙节点的归并进行了研究,给出了剪力墙节点的数据结构和生成算法,提出了剪力墙节点归并的点阵表示法和矢量表示法。该文建议的方法准确,高效,能够很好地实现体型复杂的高层三维空间结构剪力墙节点的归并。     

Maximum Intensity Projection Using Splatting in Sheared Object Space

In this paper we present a new Maximum Intensity Projection (MIP) algorithm which was implemented employing splatting in a shear-warp context. This algorithm renders a MIP image by first splatting each voxel on two intermediate spaces called "worksheet" and "shear image". Then, the maximum value is evaluated between worksheet and shear image. Finally, shear image is warped on the screen to generate the result image. Different footprints implementing different quality modes are discussed. In addition, we introduced a line encoded indexing speed-up method to obtain interactive speed. This algorithm allows for a quantitative, predictable trade-off between interactivity and image quality.     

无人机着陆抗风鲁棒H_∞控制器设计研究

无人机在进场着陆过程中存在低空风切变和外界各种不确定性干扰等因素,根据无人机精确进场自动着陆性能要求,利用线性矩阵不等式凸优化方法设计鲁棒H∞控制器,在满足自动着陆系统轨迹跟踪及速度控制性能的同时,能够有效抑制低空风切变及外界不确定性干扰,将所设计的自动着陆控制律在低空风切变大气干扰下进行验证,仿真结果表明,无人机着陆下滑及拉平轨迹响应具有良好的动态跟踪性能和鲁棒性,验证了该设计方法的正确性和有效性。