Quasistatic analysis of cylindrical coplanar waveguide with multilayer dielectrics

CAD-oriented analytic formulas are given for calculating the quasistatic parameters of the cylindrical CPW with three dielectrics. The effects of the dielectric materials on the quasistatic characteristics are investigated by using conformal mapping techniques. The calculated results are compared with those obtained for a corresponding planar CPW and a cylindrical CPW with a single dielectric. The curvature effects on the quasistatic characteristics are discussed. Moreover, the present expressions can also be extended to the cylindrical CPW with multilayer dielectrics. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 303–314, 1998.     

CAD model of a gap in a coplanar waveguide

The partial capacitance approach and conformal mapping techniques are used to evaluate simple closed-form models for parallel and series capacitances of equivalent π-network of a symmetric gap in a CPW. Models are compared with experimental data and full wave analysis. They are useful for a wide range of CPW parameters and frequencies. © 1996 John Wiley & Sons, Inc.     

Design and simulation of a novel bridge-like coplanar waveguide for microelectromechanical systems

In this paper, a kind of novel bridge-like coplanar waveguide has been designed and simulated at 10 GHz. Compared with conventional CPW, this design has lower attenuation and wider available characteristic impedance range. In addition, this design can avoid the interference among the adjacent components of RF MEMS devices.     

A comparative study between shielded and open coplanar waveguide discontinuities

A comparative study between open and shielded coplanar waveguide (CPW) discontinuities is presented. In this study, the space domain integral equation method is used to characterize several discontinuities such as the open-end CPW and CPW series stubs. Two different geometries of CPW series stubs (straight and bent stubs) are compared with respect to resonant frequency and radiation loss. In addition, the encountered radiation loss due to different CPW shunt stubs is evaluated experimentally. The notion of forced radiation simulation is presented, and the results of such a simulation are compared to the actual radiation loss obtained rigorously. It is shown that such a simulation cannot give reliable results concerning radiation loss from printed circuits.     

Shielded edge-coupled coplanar waveguide structures: Modes and field configurations

In this article we present the dispersion characteristics as well as frequency-dependent field configuration and characteristic impedance for edge-coupled, shielded, coplanar waveguide structures. The structures studied include conductor-backed and suspended configurations. Phenomena such as mode conversion and dispersion of the dominant modes are explained. The characteristic impedance behavior is shown to be directly related to the phenomenon of mode conversion. The analysis uses the method of lines. © 1996 John Wiley & Sons, Inc.     

基于共平面波导的可调低通滤波器的设计和制作

介绍了一种使用多触点MEMS开关实现的新型可调微波MEMS低通滤波器,应用MEMS制作工艺在石英衬底上实现滤波器结构.滤波器基于慢波共平面波导周期性结构,具有尺寸小、插损低、可与单片微波集成电路工艺兼容等优点.滤波器截止频率的大小取决于MEMS开关的状态.实验结果表明,当MEMS开关受到激励时,低通滤波器的3-dB截止频率从12.5GHz转换至6.1GHz,带内纹波小于0.5dB,带外抑制大于40dB,开关的驱动电压在25V左右.     

A microfluidic sensor in coplanar waveguide configuration for localized micrometric liquid spectroscopy in microwaves regime

Microsystem Technologies - In this work, we present a sensor suitable for performing the spectroscopy on a localized micrometric volume of a generic liquid, in the spectral range comprised between...     

Analysis of a shielded elevated coupled coplanar waveguide using a modified finite element method

An elevated coupled coplanar waveguide is proposed and analyzed with a view to exploit the advantage of miniaturization that is possible with elevated coplanar waveguide structures. The influence of elevation on the directional characteristics of the elevated coupled coplanar waveguide has also been studied. The proposed structure is analyzed using a modified universal matrices finite element method. © 1996 John Wiley & Sons, Inc.     

A solution method for the linear static Stackelberg problem usingpenalty functions

A new solution technique is presented for the linear constrained static Stackelberg problem. For a given value of x, the leader's decision vector, the follower is at its rational reaction set when the duality gap of the second-level problem becomes zero. The outer problem is solved by appending to the leader's objective, a function that minimizes the duality gap of the follower's problem. This structure leads to the decomposition of the composite problem into a series of linear programs leading to an efficient algorithm. It is proved that optimality is reached for an exact penalty function, and the method is illustrated with some examples     

Product form solution for generalized stochastic Petri nets

In this paper, we show the structural characteristics that a particular class of generalized stochastic Petri nets must exhibit in order for their stationary probabilities to have a product-form. Sufficient conditions for identifying such a class are derived and proven with the development of a series of transformations that can also be used to construct, for any GSPN of the class, an equivalent SPN. These resulting SPNs represent the structures that can be analyzed with standard methods for product-form SPNs to establish whether the original GSPNs have product-form solutions and to compute their performance indices with effective approaches based on computationally efficient algorithms that avoid the generation of their underlying state spaces.     

On a static generalization of the Schwarzschild solution

By mean of the method of singular sources it is possible to construct gravitational multipoles which generalize the Schwarzschild solution. Talk given at the International Conference RUSGRAV-13, June 23–28, 2008, PRUR, Moscow.     

A solution method for the static constrained Stackelberg problem via penalty method

This note presents a new solution method for the static constrained Stackelberg problem. Through our approach, the Stackelberg problem is completely transformed into a one-level unconstrained problem such that the newly introduced overall augmented objective function is minimized with repect to the leader's and the follower's variables jointly. It can be proved that a sequence of solutions to the transformed problems converges to the solution of the original problem, when the penalty parameters are updated.     

An approximate solution for the static beam problem and nonlinear integro-differential equations

We consider a Kirchhoff type nonlinear static beam and an integro-differential convolution type problem, and investigate the effectiveness of the Optimal Homotopy Asymptotic Method (OHAM), in solving nonlinear integro-differential equations. We compare our solutions via the OHAM, with bench mark solutions obtained via a finite element method, to show the accuracy and effectiveness of the OHAM in each of these problems. We show that our solutions are accurate and the OHAM is a stable accurate method for the problems considered.     

Iterative procedure for solution of sylvester generalized matrix equation

An iteration procedure for solving Sylvester generalized matrix equation is proposed in this paper. The sufficient conditions of stability of the iteration procedure for solving this equation are obtained. Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 183–186, May–June, 2000.     

Quasi-analytical finite element procedures for axisymmetric anisotropic shells and solids

Using complex series representations, a quasi-analytical finite element procedure is developed which can analyze the static and dynamic mechanical fields of anisotropic axisymmetric shells and bodies. Due to its generality the procedure can handle arbitrary laminate construction with possible meridional and radial variations in locally or globally mechanically anisotropic materials. In this respect, in contrast to traditional quasi-analytical procedures which are limited to the ‘specially’ orthotropic case, the present treatment reveals several important effects of material and/or structural anisotropy. To illustrate the procedure as well as the significant effects of material anisotropy, several numerical examples are given along with comparisons with known analytical treatments.     

An asymmetric coplanar waveguide （ACPW） resonant antenna based on the composite right/left-handed transmission line

An asymmetric coplanar waveguide （ACPW） resonant antenna based on a composite right/left- handed transmission line （CRLH TL） is presented. The proposed antenna consists of an asymmetric coplanar waveguide feeding line and mushroom unit cells. Based on the fundamental structure, an improvement on the antenna is implemented. Two novel structures including a strip-shaped extended ground plane and a rectangular extended ground plane are studied. The antenna with the strip-shaped extended ground plane exhibits bandwidth enhancement characteristics. The operating bandwidths with 10 dB return loss over 210 MHz （1.57-1.78 GHz） is obtained. The fractional bandwidth is enhanced from 0.31% to 12.5%, an improvement factor of approximately 40.32. Meanwhile, the antenna with the rectangular extended ground plane presents broadband features. From measured results, the impedance bandwidth over 3.19 GHz （2.65-5.84 GHz） was occupied. It covers WiMAX 3.5/5.5 GHz and WLAN 5.2/5.8 GHz bands, and therefore could well apply to WiMAX/WLAN systems. Further, the radiation patterns, peak gain and radiation efficiency are also presented and discussed.     

On the stability of solution mapping for parametric generalized vector quasiequilibrium problems

In this paper, we study the solution stability for a class of parametric generalized vector quasiequilibrium problems. By virtue of the parametric gap function, we obtain a sufficient and necessary condition for the Hausdorff lower semicontinuity of the solution mapping to the parametric generalized vector quasiequilibrium problem. The results presented in this paper generalize and improve some main results of Chen et al. (2010) [34], and Zhong and Huang (2011) [35].     

A numerical method for the solution of static and dynamic three-dimensional elasticity problems

Kupradze's functional equation, reduced to a regular Fredholm integral equation of the first kind, was solved by applying a new numerical method, based on numerical integration, whose collocation points are chosen in self-similar surfaces. An application of the method to a particular problem of elasticity demonstrated a sufficient accuracy and stability of the method. It was shown that the proposed method is faster, simpler and more easily programmable than the existing classical methods. Finally, suggestions were made for a better use of the method and for possible improvements.     

An analytical solution for static stability of multi-scale hybrid nanocomposite plates

An analytical answer to the buckling problem of a composite plate consisted of multi-scale hybrid nanocomposites is presented here for the first time. In other words, the constituent material of the structure is made of an epoxy matrix which is reinforced by both macro- and nanosize reinforcements, namely, carbon fiber (CF) and carbon nanotube (CNT). The effective material properties such as Young’s modulus or density are derived utilizing a micromechanical scheme incorporated with the Halpin–Tsai model. To present a more realistic problem, the plate is placed on a two-parameter elastic substrate. Then, on the basis of an energy-based Hamiltonian approach, the equations of motion are derived using the classical theory of plates. Finally, the governing equations are solved analytically to obtain the critical buckling load of the system. Afterward, the normalized form of the results is presented to emphasize the impact of each parameter on the dimensionless buckling load of composite plates. It is worth mentioning that the effects of various boundary conditions are covered, too. To show the efficiency of presented modeling, the results of this article are compared to those of former attempts.

     

Algorithms for coplanar camera calibration

Abstract. Coplanar camera calibration is the process of determining the extrinsic and intrinsic camera parameters from a given set of image and world points, when the world points lie on a two-dimensional plane. Noncoplanar calibration, on the other hand, involves world points that do not lie on a plane. While optimal solutions for both the camera-calibration procedures can be obtained by solving a set of constrained nonlinear optimization problems, there are significant structural differences between the two formulations. We investigate the computational and algorithmic implications of such underlying differences, and provide a set of efficient algorithms that are specifically tailored for the coplanar case. More specifically, we offer the following: (1) four algorithms for coplanar calibration that use linear or iterative linear methods to solve the underlying nonlinear optimization problem, and produce sub-optimal solutions. These algorithms are motivated by their computational efficiency and are useful for real-time low-cost systems. (2) Two optimal solutions for coplanar calibration, including one novel nonlinear algorithm. A constraint for the optimal estimation of extrinsic parameters is also given. (3) A Lyapunov type convergence analysis for the new nonlinear algorithm. We test the validity and performance of the calibration procedures with both synthetic and real images. The results consistently show significant improvements over less complete camera models. Received: 30 September 1998 / Accepted: 12 January 2000