共查询到20条相似文献,搜索用时 109 毫秒
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何海涛 《CAD/CAM与制造业信息化》2011,(12):53-55
本文以二维绘图软件AutoCAD为平台,利用VBA开发工具,依据平面图形的平行移轴公式、转轴公式,实现了计算截面对任意轴的静距和惯性矩的程序设计。从而简化了计算过程,减少重复性工作。 相似文献
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基于变极距电容传感器工作原理,导出测容或测频方法求算物体微小伸长量或固体材料杨氏弹性模量的基本公式,用该公式对合金钢材料弹性模量进行了计算分析,计算结果与实测值吻合良好,表明该公式具有工程实用价值。 相似文献
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针对复杂函数的数值积分问题,给出了若干个任意分割积分区间的数值积分的误差结果,并提出一种基于遗传算法的不等距节点分割的数值积分方法。该方法初始时在积分区间内任意选取一定的节点,通过遗传算法优化这些节点,在相邻节点间利用Simpson公式近似计算积分,最后得到较准确的积分结果。数值计算结果表明,该方法计算精度高,而且可以计算奇异函数及震荡函数的积分。 相似文献
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摄像机内参数自标定——理论与算法 总被引:3,自引:0,他引:3
讨论如何通过摄像机的旋转运动标定其内参数.当摄像机绕其坐标轴旋转时,运用
代数方法给出了计算内参数的公式.该公式在2D投影变换接近理论值P时是非常实用的.
在摄像机绕未知轴旋转时,根据相应的2D投影变换,运用矩阵特征向量理论给出了内参数的
通解公式.通过摄像机绕两个不同未知轴的旋转,摄像机内参数能被唯一地确定.这些结果为
摄像机自标定算法提供了理论基础,同时也给出了实用性算法.模拟实验和真实图像实验的
结果表明本文所给的算法具有一定实用价值. 相似文献
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基于walker星座拓扑结构的碰撞分析 总被引:1,自引:0,他引:1
针对walker星座,研究了轨道拓扑结构,得到了星座特有的一些性质.根据特性,分析了walker星座卫星的几个常量参数,并推导了轨道交点的交点卫星角距计算公式和严格碰撞判决公式.根据walker星座最小卫星间距的搜索计算方法,为优化确定卫星最小距离约束值,提出和推导了最小卫星间距快速计算方法,方法仅依据星座基本常量参数,与时间不关联,具有计算速度快的特点,最后给出了广义碰撞的判决条件.通过仿真实验,验证了walker星座最小卫星间距快速计算方法的精确性和快速性,体现了方法在星座设计碰撞分析中的可行性和有效性. 相似文献
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首先对椭圆线构造一个带域,并证明在此带域中所确定的像素点是误差最小的。应用带域提出了一种误差最小的椭圆生成算法,得到递推公式,每次要计算的是朝X方向或Y方向取像素点的个数,跟过去一贯采用的每生成一个像素点都要计算判别函数的传统方法比较,具有较强的优越性,尤其是对长轴与短轴相差越大的椭圆优越性越明显,最后给出了计算实例。 相似文献
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考虑现有多轴磁传感器的标定补偿方法普遍存在计算量较大、操作时间长、场地要求面积大、标定设备要求高等问题,提出了基于椭球拟合的三轴磁传感器误差标定补偿方法。在分析传感器误差产生机理的基础上,建立了磁传感器误差模型,推导了误差系数的解算公式,并利用椭球拟合的方法对三轴磁传感器进行了测试标定与误差补偿。实验结果表明,该方法能够正确、有效地标定补偿三轴磁传感器不正交误差、灵敏度误差和零偏误差,具有修正过程简捷、省时、精度高特点不依赖于精密仪器提供准确的方向基准、水平基准等,能够广泛应用于多轴矢量传感器的误差标定和有效补偿。 相似文献
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介绍了一种基于边界点计算形状矩特征的算法,并采用该算法计算了目标的形状特征。结果表明该算法比传统的矩特征计算方法是具有高的运算速度。 相似文献
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Robust excitation of a large spin ensemble is a long-standing problem in the field of quantum information science and engineering and presents a grand challenge in quantum control. A formal theoretical treatment of this task is to formulate it as an ensemble control problem defined on an infinite-dimensional space. In this paper, we present a distinct perspective to understand and control quantum ensemble systems. Instead of directly analyzing spin ensemble systems defined on a Hilbert space, we transform them to a space where the systems have reduced dimensions with distinctive network structures through the introduction of moment representations. In particular, we illustrate the idea of moment quantization for a spin ensemble and illuminate how this technique leads to a dynamically equivalent control system of moments. This equivalence enables the control of spin ensembles through the control of their moment systems, which in turn creates a new control analysis and design paradigm for quantum ensemble systems based on the use of truncated moment systems. 相似文献
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基于不变矩特征和神经网络的人脸识别模型 总被引:9,自引:1,他引:9
不变矩是图像的一种统计特征,具有平移不变性、旋转不变性和比例不变性,广泛应用于图像识别。该文将图像矩阵的不变矩作为识别特征,建立了人脸识别模型。将人脸图像经过不变矩特征提取、不变矩矢量标准化及不变矩矢量排列处理后,运用BP网络进行识别,经过竞争选择,获得识别结果。利用ORL人脸数据库进行仿真实验,结果表明,该文的人脸识别模型实现简单、识别率高、训练速度与识别速度较快、便于实时实现。 相似文献
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Strip noise will cover the real radiation information of remote sensing image,which not only reduces image quality,but also application effect.Aiming at the problem that window moment matching is difficult to remove strip noise thoroughly for the non\|uniform image,the wavelet moment matching algorithm is proposed.Firstly,the low frequency wavelet coefficient and the high frequency wavelet coefficients are separated which based on the wavelet multiresolution characteristic.Secondly,the low frequency wavelet coefficients were filtering by window moment matching,while strip noise of high frequency wavelet coefficients was performed by threshold method.Finally,reconstruction of the wavelet coefficients obtained destriping image.The above mentioned algorithm was evaluated quantitatively by local PSNR,local SSIM,Fuzzy coefficient and goodness of fit index.Results show that the wavelet moments matching algorithm is superior to the moment matching,wavelet soft threshold and window moment matching algorithm.Wavelet moment matching improves limitation of uniform distribution of grayscale value based on window moment matching,combining the advantages of spatial and frequency domain denosing,which can remove the noise while preserving the details of the image. 相似文献
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Florica Mindru Tinne Tuytelaars Luc Van Gool Theo Moons 《Computer Vision and Image Understanding》2004,94(1-3):3
Generalised color moments combine shape and color information and put them on an equal footing. Rational expressions of such moments can be designed, that are invariant under both geometric deformations and photometric changes. These generalised color moment invariants are effective features for recognition under changing viewpoint and illumination. The paper gives a systematic overview of such moment invariants for several combinations of deformations and photometric changes. Their validity and potential is corroborated through a series of experiments. Both the cases of indoor and outdoor images are considered, as illumination changes tend to differ between these circumstances. Although the generalised color moment invariants are extracted from planar surface patches, it is argued that invariant neighbourhoods offer a concept through which they can also be used to deal with 3D objects and scenes. 相似文献
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介绍了一种基于边缘点计算矩特征的方法,该算法实现思路清晰,编程实现简单,结果准确,且可应用到其他形状特征的计算中。 相似文献
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This paper concerns with numerical approximations of solutions of fully nonlinear second order partial differential equations
(PDEs). A new notion of weak solutions, called moment solutions, is introduced for fully nonlinear second order PDEs. Unlike
viscosity solutions, moment solutions are defined by a constructive method, called the vanishing moment method, and hence,
they can be readily computed by existing numerical methods such as finite difference, finite element, spectral Galerkin, and
discontinuous Galerkin methods. The main idea of the proposed vanishing moment method is to approximate a fully nonlinear
second order PDE by a higher order, in particular, a quasilinear fourth order PDE. We show by various numerical experiments
the viability of the proposed vanishing moment method. All our numerical experiments show the convergence of the vanishing
moment method, and they also show that moment solutions coincide with viscosity solutions whenever the latter exist.
This work was partially supported by the NSF grants DMS-0410266 and DMS-0710831. 相似文献