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11.
Howard T. Moncarz 《Journal of research of the National Institute of Standards and Technology》2002,107(2):193-205
Geometric dimensioning and tolerancing (GD&T) is a method to specify the dimensions and form of a part so that it will meet its design intent. GD&T is difficult to master for two main reasons. First, it is based on complex 3D geometric entities and relationships. Second, the geometry is associated with a large, diverse knowledge base of dimensional metrology with many interconnections. This paper describes an approach to create a dimensional metrology knowledge base that is organized around a set of key concepts and to represent those concepts as virtual objects that can be navigated with interactive, computer visualization techniques to access the associated knowledge. The approach can enable several applications. First is the application to convey the definition and meaning of GD&T over a broad range of tolerance types. Second is the application to provide a visualization of dimensional metrology knowledge within a control hierarchy of the inspection process. Third is the application to show the coverage of interoperability standards to enable industry to make decisions on standards development and harmonization efforts. A prototype system has been implemented to demonstrate the principles involved in the approach. 相似文献
12.
The current study replicated, in a sample of 2,300 outpatients seeking psychiatric treatment, a previous study (R. F. Krueger & M. S. Finger, 2001) that implemented an item response theory approach for modeling the comorbidity of common mood and anxiety disorders as indicators along the continuum of a shared latent factor (internalizing). The 5 disorders examined were major depressive disorder, social phobia, panic disorder/agoraphobia, specific phobia, and generalized anxiety disorder. The findings were consistent with the prior research. First, a confirmatory factor analysis yielded sufficient evidence for a nonspecific factor underlying the 5 diagnostic indicators. Second, a 2-parameter logistic item response model showed that the diagnoses were represented in the upper half of the internalizing continuum, and each was a strongly discriminating indicator of the factor. Third, the internalizing factor was significantly associated with 3 indexes of social burden: poorer social functioning, time missed from work, and lifetime hospitalizations. Rather than the categorical system of presumably discrete disorders presented in DSM-IV, these 5 mood and anxiety disorders may be alternatively viewed as higher end indicators of a common factor associated with social cost. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
由于在机器人导航等领域新的图像装置不符合透视规则,无法运用传统的透视位置估计方法,采用吴氏零点分解方法,给出非透视3点问题的解析解.利用新图像装置的几何条件,建立了非透视3点方程系统. 相似文献
14.
一种探测二维电磁目标的新方法 总被引:2,自引:0,他引:2
电磁目标的探测对通信而言有着十分重要的意义。本文描述一种收敛迅速、结果准确、抗强随机噪声的探测二维电磁目标的新方法。首先从体等效原理出发得到一个积分方程组,此方程组可求解散射问题。随后,对此方程组求变分,变形后得到散射场变化与介电参数变化之间关系的矩阵方程,即反演方程。文中列举了几个例子,通过数值实验结果证明本法收敛速度快、反演精度高、适应复杂目标的能力强,能抗强随机噪声干扰 相似文献
15.
1 IntroductionInmanyapplications,suchasradar,sonar,geophysics,radiocommunicationandmedicalimag ing ,theproblemoftwo dimensionalfrequencyesti mationhasreceivedalotofattentioninrecentyears.InthecaseofadditivewhiteGaussiannoise,numerousmethodssuchasMEMP[1 ] ,MUS… 相似文献
16.
从实践上论述了UHE电弧炉炼钢的工艺特点,提出UHE电炉的“新三期”的新观点,并作了定量的描述;对正在发展中的UHE电炉工艺与设备提出了策略性的意见. 相似文献
17.
Xu You-heng Dong Li-yun Huang Dong-qun Fudan University Shanghai P. R. China 《水动力学研究与进展(B辑)》1998,(3)
In this paper,the oscillation amplitude of the free end of a group of threecylinders are studied.The three cylinders are erected at the vertices of an equilateral trian-gle,and three arrangements are made in this study.One of the three cylinders is served asa working cylinder which is mounted by a flexible cantilever and two accelerometers areattached on the free end in two directions.The results of the three-cylinder arrangementare compared with those of two cylinders in tandem/side-by-side arrangement in the samecondition.The experimental results show that the rear cylinder of a group of three cylin-ders is affected more seriously than that of the corresponding two cylinders in the contrastarrangement.The main direction of oscillation is changed.The transversal oscillation isstronger than the longitudinal oscillation in the three-cylinder arrangement.On the con-trary,the transversal oscillation is much weaker than the longitudinal oscillation in two-cylinder arrangement.The largest transversal oscillat 相似文献
18.
本文针对金翅岭金矿矿体开采条件极其复杂的情况,在采矿方法试验中,率先在岩金矿山采用了三强作业技术,既保证了安全回采,又取是了较好的技术经济指标。 相似文献
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