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This work presents the design of acoustic Bragg reflectors (ABRs) for unreleased MEMS resonators through analysis and simulation. Two of the greatest challenges to the successful implementation of MEMS are those of packaging and integration with integrated circuits. Development of unreleased RF MEMS resonators at the transistor level of the CMOS stack will enable direct integration into front-end-of-line...
Electrically small antennas have remained a significant topic of interest for a number of applications, particularly low frequency systems and wireless networks requiring small devices. As is well-known, there are a number of techniques whereby an electrically small antenna can be efficiently matched to a 50 Ω system impedance. Ultimately, the primary design challenge is achieving as wide an efficient...
In this paper, we investigate material perturbation as a means to introduce frequency reconfigurability into microstrip patch antennas (MPAs) and Multiple-Input Multiple-Output dielectric resonator antennas (MIMO DRAs). A detailed analysis via eigenvalue perturbation has been carried out to determine the optimal material perturbation placement for maximum frequency agility. The results obtained agree...
This paper presents part of a joint venture between Dstl and LJMU. The purpose of this work is to investigate the interaction of electromagnetic (EM) waves within a resonant microwave cavity to sense and characterise filter materials for residual life indication. This paper looks at a single filter material, ASZM-TEDA activated carbon, which is commonly used for military applications where personnel...
Applying the mixed layer wise theories and Ressiner's mixed variational theorem, the dynamics equations of viscoelastic laminated plates were deduced and the numerical solutions for simple-support laminated plates were derived through Navier solutions. Computing the natural frequency and the loss factor in the plates corresponding to the lower-rank models and analyzing the viscoelastic layer' influence...
Music is an integral part of high school students' daily lives, and most use digital music devices and services. The one-week Summer Music Technology (SMT) program at Drexel University introduces underclassmen high school students to music technology to reveal the influence and importance of engineering, science, and mathematics. By engaging participants' affinity for music, we hope to motivate and...
This paper presents a small review on the different issues that appear when miniaturizing antennas, as well as an introduction on the different techniques that are commonly used towards miniaturization. Also some alternatives based on recent developments are introduced.
The motivation for this article is to investigate properties of finite periodical structures with resonant elements immersed in a conventional dielectric. It is well known that such combination could have the properties of complex material. Particularly our goal is to apply this kind of structure to design an antenna with a circularly polarized irradiated field and with a flat pattern in a chosen...
In this work, we study for the first time the nonlinearity of AlN piezoelectric material subjected to high RF electric field (E). Nonlinear effects in BAW (Bulk Acoustic Wave) resonators are seen as a frequency shift and an amplitude variation at the resonance (fr) and anti-resonance (fa) frequencies. Moreover the coupling factor increases for high power measurements (high E). By model fittings, these...
Stents are widely used to maintain vessel patency after dilating a stenosed vessel (angioplasty). However, restenosis may occur post stent placement after weeks or months. Therefore it is necessary to monitor the patency of the stent. Non-invasive imaging methods such as CT, echocardiography, or MRI perform poorly in the detection of in-stent restenosis. As a solution of this problem a novel stent...
In order to characterize dielectric materials having very high permittivity (εr ≈ 40–140) through a non destructive method, and derived from a resonant cavity is proposed and the determination uncertainties are evaluated.
Through testing investigation and theoretical analysis, the performance change of a traveling wave ultrasonic motor is studied at cryogenic temperature. An experimental system was built up, and the motor's characteristics were tested at cryogenic conditions. The influence of temperature on the friction interface was studied by comparing the material's surface appearances. This paper provides some...
Sensing liquids and their contaminations is very important for many applications. In this paper, the LC-resonance response of circular split rings illuminated with a normal incidence light is analyzed. The tuning response of the resonant frequency upon loading various samples of liquids is described. The liquids are deposited on the array of the rings. The sensor allows to extract various information...
Frequency-selection properties for composite periodic structures are presented in this paper. The periodic cell consists of one or two scattering elements of different refractive index material situated in a background slab medium. Both high and low permittivity material are investigated in order to achieve possible resonance that can serve a particular useful purpose. It is important that the proper...
This paper presents a new improved compact, low-insertion loss, sharp-rejection, and easy to manufacture compact microstrip resonant cell (CMRC) structure [1] as microstrip or suspended-substrate microstrip lowpass filter (LPF) used in terahertz (THz) Subharmonically pumped mixer (SHM). In comparison to traditional high/low step-impedance filter used in SHM, this improved CMRC structure could shorten...
A cylindrical traveling wave ultrasonic motor using outer excitation of two bending transducers is proposed in this paper. To avoid the drawbacks of conventional traveling wave ultrasonic motors, sandwich structure of PZT elements and d33 mode of PZT are used here. Working principle and design analysis by means of FEM method are detailed. A prototype motor has been fabricated and tested. Although...
Based on the ANSYS software platforms, the structural vibration and noise of the truck cab structures have been systematically simulated and studied with test modal technology, the finite element and the boundary element methods in this text. First, modal analysis is made to obtain the structure's modal parameters. Then, the finite element modal is checked and verified by the test results. The dynamic...
New distributed multilayer microstrip structures are investigated in microwaves. The amplitude and phase responses are analyzed for different geometrical parameters, number of cells and dielectric constants of the dielectric layers. It is shown that the proposed structures exhibit left-handed properties in a frequency range near the resonance.
As the shielding effectiveness is greatly influenced by cavity resonance, the resonance frequency of rectangular cavity is simulated numerically using the finite-difference time-domain (FDTD) method. The influence of aperture size, embedded metal and nonmetal materials on resonance frequency of cavity is analyzed. Computation results indicate that shielding performance decreases with increment of...
Shear Wave Induced Resonance Elastography (SWIRE) has been applied to confined mimicking breast tumors. These latter have been idealized as a spherical heterogeneity embedded in an homogeneous medium transmitting torsional shear waves. First, we present a theoretical model that served to verify and physically understand the resonance induction of spheres by torsional waves. Then, experimental measurements...
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