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1.
一种连续波多站发射机及频谱分析 总被引:2,自引:2,他引:0
介绍了一种连续波多站发射机的新方案,从理论上对该机的发射频谱进行了分析,并与实际结果进行比较。理论和实际都证明该方案具有很好的交调抑制、谐波抑制和杂波抑制、相噪低等诸多优点。 相似文献
2.
The aim of the paper is to design high-order artificial boundary conditions for the Schrödinger equation on unbounded domains in parallel with a treatment of the heat equation. We first introduce a circular artificial boundary to divide the unbounded definition domain into a bounded computational domain and an unbounded exterior domain. On the exterior domain, the Laplace transformation in time and Fourier series in space are applied to achieve the relation of special functions. Then the rational functions are used to approximate the relation of the special functions. Applying the inverse Laplace transformation to a series of simple rational function, we finally obtain the corresponding high-order artificial boundary conditions, where a sequence of auxiliary variables are utilized to avoid the high-order derivatives in respect to time and space. Furthermore, the finite difference method is formulated to discretize the reduced initial–boundary value problem with high-order artificial boundary conditions on a bounded computational domain. Numerical experiments are presented to illustrate the performance of our method. 相似文献
3.
For the analysis of noise problems in medium-to-high frequency ranges, the energy flow boundary element method (EFBEM) has been studied. EFBEM is numerical analysis method of energy flow analysis (EFA), and solves energy governing equations using a boundary element method in complex structures. Based on EFBEM, a noise prediction software, “noise analysis system by energy flow analysis” (NASEFA), was developed. For effective maintenance, NASEFA is composed of three main modules: the translator, the model converter, and the main solver. The translator changes the FE model to the NASEFA BE model, and the model converter changes the BE model to an EFBE model, including various data, such as structural materials, medium properties, sources, and boundary conditions. NASEFA then solves the acoustic energy density and intensity on boundary and in the field. Moreover, it analyzes interior and exterior noise problems for single and multiple domains in two and three dimensions. Finally, for the validation of the software developed, interior and exterior noise predictions of various structures were performed. The results obtained with NASEFA were compared with those of the commercial SEA program and experiment. From these comparative studies, the usefulness of NASEFA was established. 相似文献
4.
5.
Sang-Eon Han 《Information Sciences》2006,176(3):332-348
During the past 20 years the research of digital surfaces has proceeded to find their properties in the digital space Zn, such as a topological number, a simple k-point, the 3D-Jordan theorem, a k-separating set, a boundary detecting algorithm and so on. Actually, unlike surfaces in a continuous space, the features of digital surfaces have different characteristics. The aim of this paper is to introduce the notion of a digital closed k-surface in Zn, n ? 3, with the general k-adjacency relations as a generalization of Malgouyres’ and Morgenthaler’s k-surfaces in Z3, to establish some minimal simple closed k-surfaces in Z3 and to find their digital topological properties in relation with the k-fundamental group and k-contractibility. Moreover, a connected sum of two digital closed surfaces is introduced and its digital topological properties are investigated. 相似文献
6.
Richard I. Hartley Frederik Schaffalitzky 《International Journal of Computer Vision》2009,83(3):274-293
In this paper a general procedure is given for reconstruction of a set of feature points in an arbitrary dimensional projective
space from their projections into lower dimensional spaces. This extends the methods applied in the well-studied problem of
reconstruction of scene points in ℘3 given their projections in a set of images. In this case, the bifocal, trifocal and quadrifocal tensors are used to carry
out this computation. It is shown that similar methods will apply in a much more general context, and hence may be applied
to projections from ℘
n
to ℘
m
, which have been used in the analysis of dynamic scenes, and in radial distortion correction. For sufficiently many generic
projections, reconstruction of the scene is shown to be unique up to projectivity, except in the case of projections onto
one-dimensional image spaces (lines), in which case there are two solutions.
Projections from ℘
n
to ℘2 have been considered by Wolf and Shashua (in International Journal of Computer Vision 48(1): 53–67, 2002), where they were applied to several different problems in dynamic scene analysis. They analyzed these projections using
tensors, but no general way of defining such tensors, and computing the projections was given. This paper settles the general
problem, showing that tensor definition and retrieval of the projections is always possible. 相似文献
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9.
冷成型工艺多用于实体件和套筒件的加工,对于具有台阶孔的零件,在生产领域应用极少。EPB传动螺母是一个异形台阶孔件,其台阶小孔与大孔值差较小,且外部成形端在大孔端,成形工艺较为复杂。根据经验,利用三维软件设计加工工艺,并利用冷成型分析软件Deform-3D进行数值模拟,分析其可行性。 相似文献
10.
文章以南京理工大学“十五”三期教工集资住宅为例,介绍了挤塑聚苯乙烯泡沫板(FWB)外墙外保温系统的施工工艺和质量控制要点,以及在施工实践中的一些体会。 相似文献