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1.
为了在空气炮内弹道测速中提高光纤准直器的工作距离,对光纤准直器结构进行改进,以实现远距离探测。列举了几种常见的准直透镜。从高斯光束原理以及可实现光学探测工作距离的角度出发,在C-LENS透镜原理基础上,提出了直径为16 mm的空气炮弹丸测速装置,并设计了长距离光纤准直器。在ZEMAX软件中对准直器进行仿真,利用优化函数求出透镜最大工作距离,并通过光束质量分析仪检测准直器性能指标。仿真结果进一步验证了准直器的可行性。通过在导轨上进行长距离返回光耦合效率试验,证明了该设计基本满足10~1 500 mm的探测要求,为光纤准直器的长距离测量提供了技术参考。  相似文献   

2.
基于分水岭变换的粘连颗粒图像分割方法   总被引:1,自引:0,他引:1  
提出了一种基于分水岭变换的粘连颗粒图像分割方法. 首先对图像进行预处理,进行二值化;然后通过距离变换和灰度形态重构得到每个目标的种子区域(目标标记);再根据目标标记使用强制最小技术修正距离变换图;最后,对修正后的距离变换图进行分水岭变换,得到分割结果. 在Matlab环境下进行实验,结果表明该算法效果良好,能有效的抑制过分割.  相似文献   

3.
为解决现有汉字细化算法中的骨架断裂、交叉点畸变等问题,提出一种K-P (Kmeans++-PCA)算法,优化现有的手写汉字细化算法。提出交叉点匹配模板,减少骨架毛刺去除时对非交叉点的遍历,借助主成分分析算法与端点距离对骨架断点进行连接判断,对骨架交叉点畸变进行处理,使用点到边界方向距离算法提取交叉区域后结合Kmeans++聚类对畸变区域进行分析,利用笔画走势信息对骨架进行修复并使用B样插值算法完成骨架重建。将优化后的算法在手写汉字数据集上进行实验,验证了优化后的算法优于优化前的算法。  相似文献   

4.
针对离散Reeb图(Discrete Reeb Graph,DRG)描述人体骨架时分支部位骨架线偏离中轴的问题,采用了能量函数最小化的方法对DRG曲线进行优化。将人体模型的DRG曲线作为初始骨架,定义其能量函数,在点云模型的距离场梯度的作用下,迭代地调整偏离中轴目标段的曲线位置使其逐渐逼近中轴,能量函数最小时得到优化的骨架。将该算法应用于同一模特四个不同姿势和四个不同模特同一姿势的人体点云模型,并与基于拉普拉斯算子的点云收缩的骨架提取方法进行了比较。结果表明,该算法能够很好地适应各种不同姿势和体型,模型分叉部位的特征得到更加完善的描述,得到的骨架曲线更接近模型的中轴。  相似文献   

5.
针对有向传感器网络(Directional Sensor Networks, DSNs)探测区域中PIR(Pyroelectric Infrared Sensor)传感器节点部署问题,设计了4种基于几何形状的节点部署方案,计算了各部署方案的节点密度。基于修改后的TIS测试编写仿真算法,在Matlab平台上对各节点部署方案进行了仿真实验,统计不同部署方案下的目标检测率,并对实验数据进行分析。结果表明,设计的4种部署方案的目标检测率均高于随机部署约10%;等腰三角形部署方案适用于节点数目充足的情况,能实现探测区域全覆盖,目标检测率可达80%以上;正方形部署方案适用于节点数目有限的情况,能实现探测区域大部分覆盖,目标检测率可达75%以上。  相似文献   

6.
自适应提升小波变换及飞机发动机故障分析   总被引:1,自引:1,他引:0       下载免费PDF全文
小波提升方案通过改变预测器和更新器构造出所需要的小波,这为机械设备故障特征分析中小波基函数的选择提供了方便。为了能在每个尺度上自适应选择与机械振动信号特征匹配的小波基函数,提出了一种更新器和预测器同时自适应地提升小波变换方法。在此方法中,采用先更新后预测的提升方案,分别通过信号的局部梯度大小和最小化预测误差来实现自适应更新和预测。将此方法应用在某飞机发动机故障分析中,实验结果表明,与经典小波变换相比该自适应提升小波变换分离的故障特征更明显效果更好。  相似文献   

7.
无线传感器网络(WSNs)覆盖是WSNs的关键问题,它反映了网络对目标区域的探测能力,节点的感知距离的优化能够很好地解决WSNs区域覆盖要求的同时使得能量消耗最低.研究了基于节点感知距离参数调节的WSNs节能区域覆盖方案,建立了感知半径之和最小的数学模型,采用遗传算法求解该模型,得到一个最优解.仿真结果表明:与传统覆盖方案比较,所提方案在满足覆盖要求的同时有效地降低了网络能量消耗.  相似文献   

8.
变尺度法是优化方法中应用较广的一个分枝。Davidon提出了一个方案。在每个迭代步中只须计算一次目标函数及其梯度而省去对目标函数的一维寻查。这样的方法对容易用解析法计算梯度而目标函数计算量较大的问题尤其有利。作者近年已将此法先后应用于CNDO/2几何优化、MNDO几何优化、Mossbauer谱分解、流体状态方程中常数的确定、键能与键长的非线性相关等工作。这些实践表明此法有对初值依赖不大、收敛性  相似文献   

9.
针对调强放射治疗中基于等效均匀剂量线性目标函数的物理生物混合准则模型的不足,利用正则化理论构造了最大函数的平滑和凸正则化函数,改进了基于等效均匀剂量线性目标函数的混合准则放疗规划模型,解决了原模型限制优化算法寻优能力和难以确定梯度算法步长的问题。实验证明,该方法可以在保证相似靶区剂量覆盖特性的前提下,更好地保护危及器官,提高了放疗计划质量。  相似文献   

10.
导向式灰盒模糊测试是一种能够快速对程序指定位置进行测试的技术。通过对当前导向式灰盒模糊测试技术导向不够精确的问题进行分析,提出一种新的导向式灰盒模糊测试方法,并引入基本块权重与函数路径长度的概念。通过对被测程序的静态分析,构建被测程序的函数调用图和控制流程图,计算更准确的基本块距离并插桩到被测程序中。在模糊测试时通过插桩追踪并计算每个测试用例到指定目标的距离,模糊测试器依据该距离计算种子能量以实现对目标区域的导向,并基于该方法实现原型系统Afl-guide。实验结果表明,与现有的导向式模糊测试方法相比,该方法对目标区域导向更精确、路径覆盖更广,能够更快地生成覆盖程序指定位置的测试用例。  相似文献   

11.
In this paper, we propose an improvement of the classical parametric active contours. The method, presented here, consists in adding a new energy term based on attraction point distance map chosen on the object. This additional term acts as attraction forces that constrain the contour to remain in the vicinity of the object. The distance map introduced here differs from the classical one since it is not based on the whole binary image, but rather constitutes a simplified and very fast version that relates only to one point. The additional forces, so introduced, act as a kind of balloon method. The attracting point is selected on an image based the shape of the object of interest. To improve convergence, we also propose the use of weighting factors for the externals forces as dependent on snake points. The method is evaluated for object segmentation in images, and is also tested for multi-object segmentation. Compared to the conventional balloon method, the presented approach admits a faster convergence and provides better results in particular at object concavities.  相似文献   

12.
Variational sphere set approximation for solid objects   总被引:1,自引:0,他引:1  
We approximate a solid object represented as a triangle mesh by a bounding set of spheres having minimal summed volume outside the object. We show how outside volume for a single sphere can be computed using a simple integration over the object’s triangles. We then minimize the total outside volume over all spheres in the set using a variant of iterative Lloyd clustering that splits the mesh points into sets and bounds each with an outside volume-minimizing sphere. The resulting sphere sets are tighter than those of previous methods. In experiments comparing against a state-of-the-art alternative (adaptive medial axis), our method often requires half as many spheres, or fewer, to obtain the same error, under a variety of error metrics including total outside volume, shadowing fidelity, and proximity measurement.  相似文献   

13.
周飞  刘桂华  徐锋 《测控技术》2019,38(11):76-80
针对实际水面复杂环境提出了一种基于视觉显著性的水面垃圾目标检测算法。首先对输入图像进行超像素分割,在CIELab、RGB和HSV颜色空间中提取超像素级的显著性特征,然后使用随机森林回归器将显著性特征进行融合得到疑似显著性图,并使用自适应阈值分割得到疑似二值显著性图,最后使用MLP分类器对原始图像中的疑似垃圾目标区域进行判别,去除水波、倒影和反光的干扰,最终检测出水面的垃圾目标。实验结果表明所提基于视觉显著性的水面垃圾目标检测算法的性能优于其他水面目标检测算法。  相似文献   

14.
In this paper we present a novel method to approximate the force field of a discrete 3d object with a time complexity that is linear in the number of voxels. We define a rule, similar to the distance transform, to propagate forces associated with boundary points into the interior of the object. The result of this propagation depends on the order in which the points of the object are processed. Therefore we analyze how to obtain an order‐invariant approximation formula. With the resulting formula it becomes possible to approximate the force field and to use its features for a fast and topology preserving skeletonization. We use a thinning strategy on the body‐centered cubic lattice to compute the skeleton and ensure that critical points of the force field are not removed. This leads to improved skeletons with respect to the properties of centeredness and rotational invariance.  相似文献   

15.
We present a method for rendering approximate soft shadows and diffuse indirect illumination in dynamic scenes. The proposed method approximates the original scene geometry with a set of tightly fitting spheres. In previous work, such spheres have been used to dynamically evaluate the visibility function to render soft shadows. In this paper, each sphere also acts as a low‐frequency secondary light source, thereby providing diffuse one‐bounce indirect illumination. The method is completely dynamic and proceeds in two passes: In a first pass, the light intensity distribution on each sphere is updated based on sample points on the corresponding object surface and converted into the spherical harmonics basis. In a second pass, this radiance information and the visibility are accumulated to shade final image pixels. The sphere approximation allows us to compute visibility and diffuse reflections of an object at interactive frame rates of over 20 fps for moderately complex scenes.  相似文献   

16.
为了实现养殖场环境下无接触、高精度的奶牛个体有效识别,针对SSD(single shot multibox detector)算法识别准确率不高的问题,提出一种基于浅层特征模块的改进SSD(shallow feature module SSD,SFM-SSD)算法。将原始SSD算法的主干网络由VGG16替换为MobileNetV2,以降低网络的运算量,改善检测的实时性;针对SSD网络结构的浅层特征图设计浅层特征模块,扩大浅层特征图的感受视野,提高浅层特征图对目标物体的特征提取能力;利用[K]均值聚类算法重构区域候选框,提高算法的检测精度。实验结果表明:在奶牛个体识别任务中,SFM-SSD算法的平均准确率比原始的SSD算法提升3.13个百分点。同时检测的实时性也得到改善。  相似文献   

17.
计算机动画关键帧插补技术综述   总被引:1,自引:0,他引:1  
对计算机辅助动画制作过程中关键帧的插补技术进行了研究。线性插值法通过给定的起始帧和结束帧对应点之间的直线距离算出中间插值帧。移动点约束条件插补法利用随时间空间变化的曲线与彩体上的点相关联,来控制关键帧上对应控制点的轨迹以厦动态特征。骨架插补法是将图形抽象成骨架,然后进行插补。  相似文献   

18.
Collision detection is critical for applications that demand a great deal of spatial interaction among objects. In such applications the trajectory of an object is often not known in advance either since a user is allowed to move an object at his/her will, or since an object moves under the rules that are hard to describe by exact mathematical formulas. In this paper we present a new algorithm that efficiently detects the collisions among moving spheres with unknown trajectories. We assume that the current position and velocity of every sphere can be probed at any time although its trajectory is unknown. We also assume that the magnitude of the acceleration of each sphere is bounded. Under these assumptions, we represent the bounding volume of the sphere as a moving sphere of variable radius, called a time-varying bound. Whenever the time-varying bounds of two spheres collide with each other, they are checked for actual collision. Exploiting these bounds, the previous event-driven approach for detecting the collisions among multiple moving spheres with ballistic trajectories is generalized for those with unknown trajectories. The proposed algorithm shows an interactive performance for thousands of moving spheres with unknown trajectories without any hardware help.  相似文献   

19.
A semidistributed approach is given for load balancing in large parallel and distributed systems which is different from the conventional centralized and fully distributed approaches. The proposed strategy uses a two-level hierarchical control by partitioning the interconnection structure of a distributed or multiprocessor system into independent symmetric regions (spheres) centered at some control points. The central points, called schedulers, optimally schedule tasks within their spheres and maintain state information with low overhead. The authors consider interconnection structures belonging to a number of families of distance transitive graphs for evaluation, and, using their algebraic characteristics, show that identification of spheres and their scheduling points is in general an NP-complete problem. An efficient solution for this problem is presented by making exclusive use of a combinatorial structure known as the Hadamard matrix. The performance of the proposed strategy has been evaluated and compared with an efficient fully distributed strategy through an extensive simulation study. The proposed strategy yielded much better results  相似文献   

20.
COLLISIONDETECTIONAMONGMOVINGOBJECTSINMACHININGPROCESSSIMULATIONYangHeming;LuAnsheng;ZhouJiCOLLISIONDETECTIONAMONGMOVINGOBJEC...  相似文献   

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