Search

This paper provides a comprehensive methodology for accurate analysis and design of miniaturized radio frequency (RF) surface acoustic wave (SAW) duplexer package. Full-wave analysis based on the three dimensional (3-D) finite element method (FEM) is applied to get the package model. The die model is obtained by combining the parasitics and acoustics models. The modeling of bonding wire is also discussed. The models of package, die, and bonding wires are assembled together to get the total response. Based on this methodology, several novel ideas are proposed to significantly improve the isolation. Simulation and measurement results are compared, and excellent agreement is found. The technique developed in this paper reduces the design cycle time greatly and can be applied to various RF SAW device packages. [ABSTRACT FROM AUTHOR]

This paper aims to analyse the behavior of dc corona discharge in wire-to-plane electrostatic precipitators (ESP) depending on the pressure. Current-voltage curves are analyzed particularly. Experimental results show that discharge current is strongly affected by the pressure for a given atmospheric condition. Changing the values pressure does not only changes the property of the gas but also affects the corona onset conditions and ion mobility. The finite-element method is used to solve Poisson?s equation and a modified method of characteristics is used to satisfy the current continuity condition. The two methods are repeated iteratively to obtain a selfconsistent solution of the describing equations. We used the model which separates the corona in two distinct regions. Comparing the computed results with previously obtained experimental and calculated values tests the effectiveness of this approach. The agreement with experimental results is found to be satisfactory. [ABSTRACT FROM AUTHOR]

This paper proposes a discontinuous Galerkin (DG) method combined with hierarchical reconstruction to simulate the fluid model of streamer discharges. To simulate the rapid transient streamer discharge process, a method with high resolution and high order accuracy is highly desired. Combining the advantages of finite volume and finite element method, DG is such a choice. A simulation of a double-headed streamer discharge in Nitrogen was performed using 2-dimensional fluid model. The preliminary results are quantitatively agreed with those obtained by finite volume method combined with moving mesh, indicating the potential of extending the method to general streamer simulations in complex geometries. [ABSTRACT FROM AUTHOR]

In this paper, a methodology based on shell elements is presented to model the electromagnetic behavior of multilayered conductive composite materials. The standard 3-D finite-element formulation is accomplished by a multilevel shell element representation. This leads to a reduced number of unknowns which improve the system convergence and consequently the computational time. The model developed will be validated with classical 3-D finite-element method and experimental results. [ABSTRACT FROM PUBLISHER]

A magnetically levitated motor (MLM) with two directions of movement is presented in this paper. The thrust and the levitation force of the proposed motor can be achieved simultaneously by using only a single power source. Analytical equations for the operation principle of the proposed MLM are derived. Computer simulations of the MLM characteristics by using the finite-element-analysis method are also presented. The same trend can be found between analytical equations and computer-simulation results. Then, some experimental results are provided to confirm the theoretical analysis. All of the results can provide very useful information of mechanical-structure design and control scheme development for the MLM. [ABSTRACT FROM AUTHOR]

In order to reduce the influence of axial displacement and/or to ease the assembly, certain capacitive angular sensors use symmetric designs limiting their absolute measuring range to (360°/n) where it is the number of blades. This paper presents a combined sensor that utilizes a Wiegand sensor to obtain ad. ditional information needed to resolve 360°. Since magnetic and electric fields required by the sensing principles do not interfere, one single rotor design can be used for both fields. When the receiver coil on a Wiegand sensor has to drive a current, this current influences the shape and duration of the pulse generated by the sensor. We found that shape and amplitude of the pulse vary depending on the strength of the applied fields and the location of the initial inverse nucleation. Since most of design optimization for capacitive sensors is done by means of simulations, an adequate model of the combined sensor is needed. For the capacitive part, numerical approches such as the finite element method are available. For the pulse wire part, an extended king model has been developed; results of measurements and numerical simulations are reported. [ABSTRACT FROM AUTHOR]

This paper reports on a new means of generating higher-order mode clusters of guided waves (HOMC-GW) using a meander-coil (MC) electromagnetic acoustic transducer (EMAT) in plates at frequencies significantly higher than the lower-order plate modes. These wave modes are considerably less dispersive and they occur at much higher frequency?thickness (f x d) products. Our studies cover the f x d range of 13 to 20 MHz·mm. Experimental measurements were carried out on Al plate samples of different thicknesses using three different EMAT coil periods. To understand the generation and propagation characteristics of HOMC-GW with EMATs, several simulations were carried out using 2-D finite element models at different f x d products. These simulations captured all features observed in the experiments. The time?frequency smoothed pseudo Wigner-Ville distribution (SPWVD) was used to analyze the HOMC-GW modes. Defect detection measurements using HOMC-GW generated using EMATs were made on Al plates with machined defects. [ABSTRACT FROM PUBLISHER]