傅里叶描述子相位与幅值融合方式比较

傅里叶描述子是物体轮廓分类的重要方法,当前大多数研究只利用了其幅值特征,不能满足轮廓分类的精确度要求。针对这一问题,提出了三种融合傅里叶描述子幅值和相位特征的方法对轮廓进行分类,对三种融合方法的准确性进行了比较。实验表明,基于像素级的融合方法对轮廓分类最为有效,相比于只采用幅值特征的方法准确率提高了10%,但需要的特征向量维数大大增加,判别的时效性有所降低。通过像素级融合的傅里叶描述子与曲率尺度空间描述子以及形状上下文特征在目标识别应用中的比较可以看出,傅里叶描述子具有较高的时效性。     

基于扇区投影-小波描述子的图像轮廓识别

针对传统轮廓描述子不能识别相似样本或者确定图像方向复杂等一系列缺陷,本丈提出了基于主轴归一化方法的轮廓扇区投影-小波描述子.该方法根据图像识别中的畸变不变性原理,采用先位置、大小、方向归一化,后扇区投影和小波分析的方法.该描述子不仅能消除掉主轴归一化方法的不精确性对轮廓描述的影响,而且还能够解决傅里叶描述子和环投影方法不能解决的一些特殊轮廓样本的分类问题.实验结果表明,无论是差别比较大的轮廓样本还是差别细微的轮廓样本,扇区投影-小波描述子都有着很好识别效果.     

轮廓特征与神经网络相结合的行人检测

传统的基于方向梯度直方图与支持向量机的行人检测方法运算量大,针对这一问题,本文从轮廓特征的角度出发,提出了头肩轮廓特征与神经网络相结合的检测方法。该方法根据人体头肩模型具有相对稳定性,且轮廓特征可以作为人体识别的依据,采用边缘检测与均值漂移相结合的方式提取人体轮廓,采用经PCA降维的傅里叶描述子提取轮廓特征,结合神经网络分类器完成初次人体识别。采用RGB头发模型和均值漂移方法,对遮挡情况下被判别为非人体的目标图像做进一步处理,聚类出多个人体头肩模型,重新参与分类。实验结果表明,本方法人体检测的准确率和检测速度与现有的算法相比都有所提高,且克服了遮挡情况下人体头肩模型提取错误的弊端,提高了人体检测的识别率和应用范围。     

精确型傅里叶高度函数描述子的服装款式识别方法

针对服装款式自动识别时存在提取特征困难、识别率低和分类效率低等问题,该文在精确型傅里叶高度函数(accurate Fourier height functions 2, AFHF2)与线性核函数支持向量机(support vector machine, SVM)基础上提出一种新的服装款式识别方法。首先,利用AHFH2描述子对衣服轮廓进行特征提取,对服装轮廓全局信息和局部信息进行充分表征;然后,在不需要调整参数的情况下使用线性核函数SVM对AFHF2描述子特征进行快速训练与测试。通过自建的服装图形库验证该方法的有效性,实验结果表明该算法优于现有的算法,其中AFHF2描述子优于傅里叶描述子、高度函数(HF)和TCDs等算法,线性核函数SVM算法优于径向基函数SVM算法、K-近邻算法、概率神经网络以及反向传播神经网络算法,其平均识别率能达到97.91%。     

基于Gabor小波变换的图像轮廓角点检测

传统的基于图像轮廓角点检测方法大都对图像轮廓采用高斯平滑,使得角点定位准确性较低,且对局部细微变化和噪声比较敏感.针对此问题,本文利用Gabor滤波器可以很好的表征边缘和角点梯度幅值变化信息的优良特性,采用Gabor滤波器虚部对图像轮廓进行平滑,提出基于Gabor滤波器的图像轮廓角点检测算法.与将轮廓的几何特性作为角点测度的传统算法不同,本文将Gabor滤波器平滑后轮廓像素的主方向与相邻像素方向角度差作为角点测度,提高了对噪声的鲁棒性和角点定位的准确性.实验结果表明,新算法具有较优的定位性和噪声鲁棒性.     

基于极坐标和傅里叶算子的产品形态描述方法

随着经济的发展,产品极大丰富,但同时导致了产品之间的同质性.产品形态创新设计可有效提升产品的品质,因此急需发展产品图像检索和产品形态设计自动推理技术,而其中形态描述是研究的关键之一.应用极坐标和傅里叶变换,提出产品形态描述的一种新方法,主要包括以下4个步骤：预处理,从产品图像中获取形态的轮廓信息;形态信号提取,用一个函数代表产品形态轮廓信息;信号标准化,将不同的形态进行采样点数量和大小的标准化处理;傅里叶转换,将形态信号转换到频域,即用谐波信号描述产品形态.经实例研究表明,一定数量的谐波信号就可满足产品形态的描述,该方法鲁棒性高、结构紧凑、操作简单.     

基于形状内容描述子的点特征匹配

针对两幅图像中特征点的匹配问题,本文提出了一种新的基于形状内容描述子的点特征匹配方法.该方法首先利用基于曲率尺度空间(CSS)的角点检测技术获得两幅图像中的角点及其所在的曲线;然后,计算两幅图像中每个角点的形状内容描述子,运用x2统计检验函数得到描述子的匹配度,对该匹配度进行评估,如果高于某一个阈值,则认为初始匹配成功;最后对初始匹配成功的点对,利用半局域限制完成点集之间的最终匹配.实验结果表明,本文所提出的匹配算法具有较高的点特征匹配准确率.     

Shi-Tomasi角点区域的拷贝图像检测

针对由于裁剪、翻转和旋转等产生的图像拷贝问题,提出一种Shi-Tomasi角点的拷贝检测算法.先使用Shi-Tomasi角点检测算法提取图像的局部角点;然后在以Shi-Tomasi角点为中心的圆环区域内计算特征向量的协方差描述子(多特征融合);最后通过协方差描述子的相似性度量来检测圆环区域的相似性,并以此判断检测图像是否为原图像的拷贝.实验结果证明,该检测算法对图像的裁剪、旋转等攻击具有较好的鲁棒性.     

基于支持向量机的轮胎标识点形状识别

轮胎标识点在轮胎分类中发挥着重要的作用,为了解决人工识别标识点工作强度大、误差较高等问题,提出了一种基于支持向量机的轮胎标识点形状识别算法.首先利用中值滤波对标识点图像进行降噪处理,根据标识点图像的灰度直方图对图像进行分割以去除背景,并利用Canny边缘检测算子提取标识点边缘轮廓.然后,提取标识点轮廓的傅立叶描述子系数,最后利用支持向量机对标识点的傅立叶描述子系数进行分类以识别标识点的形状.实验结果表明,该算法能准确地识别出轮胎标识点的形状,提高了标识点识别效率.     

空间傅里叶光谱仪高精密大范围动态测角技术

动态校准系统是空间傅里叶光谱仪的关键技术之一,而动态测角作为动态校准技术的一个重要环节,其测角精度和测角范围是动态校准系统性能的保证.空间傅里叶光谱仪的工作环境要求测角算法能够实现高精度和大范围的倾角检测,基于此设计了基于瞬时激光信号功率检测的动态测角算法,介绍了该算法实现的关键技术环节,给出了实验结果.算法原理和实验结果均表明该算法可以实现精度高于0.03 md和范围超过±π rad的倾角检测,可为空间傅里叶光谱仪实时获取高质量的地球大气红外辐射干涉图提供保证.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.