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The contouring error is a crucial index characterizing the surface quality of machines parts. And how to achieve an accuracy contouring error estimation value, has always been an important problem in industrial applications. Based on different desired contours, many existing methods have been introduced and analyzed. This paper proposes a contouring error computation method.
Multiobjective optimization evolutionary algorithm was used to find a set of optimum designs for non-uniform helical antennas, with turns varying from 3 to 9. The antenna parametrization proposed herein allows radii continuous variation with independent parameter per turn. The optimization procedure of antennas designs aimed to: a) maximize axial gain; b) minimize length; c) minimize impedance matching...
A novel iterative physical optics (IPO) algorithm is proposed, for the analysis of scattering from large complex geometries involving multiple reflections and complex self-shadowing effects. The algorithm involves two types of nested iterations: reflection (“bounce”) iterations and self-shadowing iterations. At each bounce iteration, the physical optics sources induced on the surface of the scatterer...
By relying on a stochastic geometry abstraction modeling for the locations of the base stations and by considering an accurate channel model based on measurements, the author of [1] has recently proposed a tractable mathematical framework for evaluating coverage and rate of millimeter wave cellular networks. The approach proposed in [1] however, relies on a noise-limited approximation for millimeter...
Discrete sinusoidal quadrature signal generators whose output frequency is numerically and instantaneously controlled are in widespread use in digital communication systems. In this paper, a numerically controlled quadrature sinusoidal signal generator that uses De Moivre trigonometric identity is proposed. Fine samples between coarsely generated De Moivre oscillator outputs are obtained using linear...
Excitation and propagation of surfaces waves in graphene and graphene nanoribbons are analyzed, within a frequency band of 1 to 300 THz, based on time dependent density functional theory, in linear response regime. The key outputs of the simulation is the ab-initio complex impeance of the materials. This is shown to tend to a continuous integral relations in graphene, when the valence and conduction...
This paper shows a frequency domain Method of Moments scattering code where spatial unknown grouping has led to low rank blocks in the system matrix and thus enabled use of the Adaptive Cross Approximation to very significantly increase the problem sizes doable on PC Workstations. Example scattering results are shown for three geometries ranging from 898,995 to 3,99,522 unknowns. Included is a 2 GHz...
The effective permittivity of a planar dielectric layer formed by 1D- and 2D-periodic structures with dielectric elements of rectangular cross section is determined by hybrid projective methods using the concept of a layer of half-wavelength thickness. Some numerical results are presented and compared to the results based on analytical expressions corresponding to the quasi-static approximation.
Gate-enclosed MOSFETs are commonly used for extreme environments with constant radiation exposure due to its radiation tolerance. Because of its annular geometry, the standard BSIM3 models do not accurately represent what happens physically on the device. An accurate model extraction can take months to complete, thus the need for a fast extraction method. Of the several model extraction methods, the...
In this paper, we build a unified analytical framework that allows for analysis and comparison of three device-to-device (D2D) mode selection schemes proposed in the literature to date, namely the distance cut-off scheme, the link gain scheme and the guard zone scheme. In the framework we adopt Poisson point process (PPP) assumptions to model the cellular and D2D interference, respectively. Using...
In this paper free-viewpoint rendering is addressed and a new fast approach for virtual views synthesis from view-plus-depth 3D representation is proposed. Depth layering in disparity domain is employed in order to optimally approximate the scene geometry by a set of constant depth layers. This approximation facilitates the use of connectivity information for segment-based forward warping of the reference...
The goal of this paper is to find the global minimum for three impulses orbital transfer between coplanar non co-axial orbits. Since there is no analytical solution for the problem, it is necessary to resort to a numerical approach. As first step, we extensively cover the space of possible solutions with the aim to get approximations for independent parameters to use as initial values for a gradient-based...
The results of experimental research of both homogeneous and heterogeneous image superimposition quality by means of multiple view geometry. One of the most important tasks in the problem of image superimposition which has not been solved till now is the task to make the right selection of a set of key (corresponding) point pairs on superimposed images. The research shows image superimposition by...
In this paper, we use stochastic geometry to characterize spatially distributed multi-antenna users within a cell that consists of a single multiple-input multiple-output (MIMO) base station (BS) equipped with a large antenna array. We also use large dimensional random matrix theory (RMT) to achieve deterministic approximations of the sum rate of this system. In particular, we consider the users inside...
Adaptive dictionary learning has become a hot-topic research field during the past decade. Though several algorithms have been proposed and achieved impressive results, they are all computationally intensive due to the lack of structure in their output dictionaries. In this paper we build upon our previous work and take a geometric approach to develop better, more efficient algorithms that can learn...
Oceanic turbulence causes distortions of the bounded beam waves propagating underwater. The most obvious effects are the beam spread and beam wandering. Propagation theory identifies two distinct measures of the beam spread: Long-Term (LT) beam spread when the beam size is measured in the fixed coordinate system, and the Short-Term (ST) beam spread when the beam size is measured relative to the instantaneous...
This work presents a simple method for estimating the nearshore wave angle along weakly curvilinear coasts. Our approach is considered an alternative to the existing, more sophisticated and precise (but also time-consuming) numerical models for practical applications at large spatial scales. The method corrects the nearshore results of Snells law using (1) the shoreline angle and (2) a coefficient...
What is it that makes movement around obstacles hard? The answer seems clear: obstacles contort the geometry of the workspace and make it difficult to leverage what we consider easy and intuitive straight-line Cartesian geometry. But is Cartesian motion actually easy? It's certainly well-understood and has numerous applications. But beneath the details of linear algebra and pseudoinverses, lies a...
This paper presents a framework for coarse scene geometry estimation, based on sparse representations of omnidirectional images with geometrical basis functions. We introduce a correlation model that relates sparse components in different views with local geometrical transforms, under epipolar constraints. By combining selected pairs of features represented by sparse components, we estimate the disparity...
This paper concerns itself with compression strategies for orientation signals, seen as signals evolving on the space of quaternion's. The compression techniques extend classical signal approximation strategies used in data mining, by explicitly taking into account the quotient-space properties of the quaternion space. The approximation techniques are applied to the case of human gesture recognition...
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