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surface-acoustic-waves
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Effect of out-of-band blockers on the required linearity, phase noise, and harmonic rejection of sdr receivers without input saw filter
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 66, Issue 11 , 2018 , Pages 4913-4926 ; 00189480 (ISSN) ; Bakhtiar, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
The required linearity of wideband receivers for applications, such as software-defined radio in the absence of input surface-acoustic wave (SAW) filters, is studied. It is shown that the required linearity of wideband SAW-less receivers is surprisingly higher than what has been commonly assumed. For these receivers, although the out-of-band blockers can reduce the compression point of the receiver, they can also potentially generate interferers that appear in the desired frequency band, resulting in higher noise floor and signal corruption. The required out-of-band IIP2 and IIP3 of low-noise amplifier (LNA) and mixer for single and concurrent applications are analytically derived. The...
Design and Fabrication of Phase Locked Loop Circuit Using SAW Oscillator
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
Low noise oscillator design has always been an important subject. Oscillators aren’t usually applicable in free-run mode. Thermal instability and high phase noise level near the carrier frequency are some of the reasons which makes the oscillator not to be used in free-run mode. Using the oscillator in a phase locked loop overcomes the mentioned problems. The oscillator considered in this project, uses a SAW resonator(1GHz). Low phase noise level at far carrier offsets, is the main feature of this oscillator. However, the near carrier phase noise isn’t good enough. Consequently, using a phase locked loop, we lock the oscillator to a low noise and stable source in order to increasing thermal...
Love Waves Propagation in a One-layered Piezo-electromagnetic Medium with Imperfect Medium-layer Interface
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
The propagation of love waves in a one-layered piezoelectric medium with slightly curved boundaries of sinusoidal type have been investigated in this study. Because of the widespread use of piezoelectric materials as surface acoustic wave (SAW) devices, sensors, actuators and in vibration control, the study of Love wave propagation in this Medias has been in the forefront of present studies in this era. But there always will be imperfection on surfaces. By employing the Taylor expansion up to the first order and using perturbation technic on the case with no irregularity and solving the problem, it has been found that along with the usual displacement components for stratified boundaries,...
Design and Fabrication of a 1GHz Low phase Noise SAW Oscillator
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
For decades Crystal Oscillators (XO) have been the unequaled references for stable and low noise frequency sources. This leadership is due to their high Q-factor. The resonant frequency of such crystal resonator is inversely proportional to the thickness of the quartz disk (the resonant cavity) and is today limited , by physical manufacturing constraints , to about 150 MHz . in order to avoid such limitation , the solution is to start with an oscillator at higher fundamental frequency. SAW technology on quartz offers this opportunity . with SAW the resonant cavity size is not linked to the thickness of the substrate and resonant frequencies up to the GHz range are achievable. In this thesis...
Surface acoustic waves as control actuator for drop removal from solid surface
, Article Fluid Dynamics Research ; Volume 53, Issue 4 , 2021 ; 01695983 (ISSN) ; Taleghani, A. S ; Rahni, M. T ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Several types of research are performed on flow control and this fact highlights the importance of this topic. Over the last two decades, actuators based on acoustic waves have attracted much attention and have been used in widespread applications from mixing to pumping. This paper reveals the effects of some control parameters such as wave amplitude and wave frequency on the dynamical behavior of a sessile drop in order to change the flow characteristics. For this purpose, the removal of water from surfaces and drop movement against gravity are considered. Flow dynamics is simulated using lattice Boltzmann method. The results show that the drop can be removed from the surface in a short...
Shear horizontal surface acoustic waves in functionally graded magneto-electro-elastic half-space
, Article Journal of Engineering Mathematics ; Volume 97, Issue 1 , 2016 , Pages 83-100 ; 00220833 (ISSN) ; Eskandari, S ; Eskandari, M ; Sharif University of Technology
Springer Netherlands
Abstract
The propagation of shear horizontal surface acoustic waves (SHSAWs) in an inhomogeneous magneto-electro-elastic (MEE) half-space with 6-mm symmetry is studied. By virtue of both the direct approach and Stroh-formalism, the dispersion relations corresponding to two general cases of material properties variation are obtained. In the first case, it is assumed that all material properties involving the MEE properties and density vary similarly in depth, whereas, the second case considers identical variation for the MEE properties, which differs from the variation of the density. The non-dispersive SHSAW velocities pertinent to the homogeneous MEE media are obtained under eight different surface...
Wide-Band RF front end for saw-less receivers employing active feedback and far out-of-band blocker rejection circuit
, Article IEEE Journal of Solid-State Circuits ; Volume 54, Issue 6 , 2019 , Pages 1528-1540 ; 00189200 (ISSN) ; Sharif Bakhtiar, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Elimination of the surface acoustic wave (SAW) filter from the input of a receiver can render it extremely vulnerable to various blockers and interferers. The presence of large out-of-band (OOB) blockers will result in the required linearity of the SAW-less receiver to be considerably higher than that of the conventional receivers with the input SAW filter. The ever-present undesirable signals that arise in the absence of the input SAW filter can be divided into two classes of far and near OOB blockers and interferers. Removal of these harmful signals requires two distinct approaches according to their nature. Two different methods for blocker and interferer rejection are introduced in this...
Simulation of blood particle separation in a trapezoidal microfluidic device by acoustic force
, Article IEEE Transactions on Electron Devices ; Volume 66, Issue 3 , 2019 , Pages 1495-1503 ; 00189383 (ISSN) ; Yazdan Parast, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Nowadays, the importance of the blood particles separation is undeniable in medical fields and there are different sorts of separation methods accordingly. Acoustic cell separation is chosen in this paper. Also, numerical methods have been used to study the effect of geometrical factors on the separation of the particles before spending time and expenses in a trial and error manner experimentally. We have implemented a plenary finite-element-based simulation of separatingblood particles such as white blood cells and platelets in an acoustic field using standing surface acoustic waves. In this paper, unlike previous works in which the channel is rectangular; the channel is trapezoidal in...
Surface/interface effect on the propagation of high-frequency SH surface waves in an ultra-thin FGP over-layer bonded to a substrate
, Article Acta Mechanica ; Volume 232, Issue 12 , 2021 , Pages 4677-4689 ; 00015970 (ISSN) ; Shodja, H. M ; Sharif University of Technology
Springer
2021
Abstract
Shear horizontal surface acoustic waves (SAW) propagation in an ultra-thin functionally graded piezoelectric (FGP) layer bonded to a homogeneous substrate is analytically formulated in the mathematical framework of surface/interface elasticity theory. It is assumed that the FGP over-layer is made of a hexagonal 6-mm crystal with a single axis of rotational symmetry coinciding with the axis of polarization. The mechanical and piezoelectric properties of the layer are assumed to vary linearly with thickness. The half-space is made of a transversely isotropic material. It should be mentioned that this model is of great interest in investigating SAW devices at high frequencies. Accounting for...
Computational simulation of water removal from a flat plate, using surface acoustic waves
, Article Wave Motion ; Volume 111 , 2022 ; 01652125 (ISSN) ; Shams Taleghani, A ; Sheikholeslam, M ; Ahmadi, G ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Minimization of drop contact time is so important and critical for applications such as self-cleaning and anti-corrosion. In recent years, surface acoustic waves are presented as a powerful method for the manipulation of the drops. In this manuscript, a numerical study of drop shedding under the effect of acoustic waves is presented, which may have potential use in the anti-icing systems. Therefore, the effects of different parameters, such as acoustic wave frequency, amplitude, and direction of the wave on the water removal, are investigated. For this purpose, a color gradient lattice Boltzmann method (LBM) is developed and used in these simulations. The acoustic actuator effect is added as...
Numerical Analysis of Drop Motion over a Flat Solid Surface Due to Surface Acoustic Waves, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Mohammad Taiebi Rahni (Supervisor) ; Shams Taleghani, Arash (Co-Supervisor)
Abstract
In recent years, there have been a tremendous research performed in the field of sestems containing small scales. However, besides all advantages of such systems, microfluidic systems have extraordinary difficulties and pumping liquid drops as part of some of these systems has been very important issue. An approach related to flow control is use of surface acoustic waves (SAW), which is known as acoustofluidic device. So far, most researches have only qualitatively investigated acoustic flux phenomenon. On the other hand, computational research is ongoing more emphasizing on accuracy, optimization, and obtaining more detailed physical understanding of SAW applications. Investigation of the...
Design and simulation of a microfluidic device for acoustic cell separation
, Article Ultrasonics ; Volume 84 , March , 2018 , Pages 234-243 ; 0041624X (ISSN) ; Boodaghi, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Experimental acoustic cell separation methods have been widely used to perform separation for different types of blood cells. However, numerical simulation of acoustic cell separation has not gained enough attention and needs further investigation since by using numerical methods, it is possible to optimize different parameters involved in the design of an acoustic device and calculate particle trajectories in a simple and low cost manner before spending time and effort for fabricating these devices. In this study, we present a comprehensive finite element-based simulation of acoustic separation of platelets, red blood cells and white blood cells, using standing surface acoustic waves...
Effects of contact angle hysteresis on drop manipulation using surface acoustic waves
, Article Theoretical and Computational Fluid Dynamics ; Volume 34, Issue 1-2 , 2020 , Pages 145-162 ; Taeibi Rahni, M ; Shams Taleghani, A ; Sharif University of Technology
Springer
2020
Abstract
Surface acoustic waves have gained much attention in flow control given the effects arising from acoustic streaming. In this study, the hydrodynamic interference of a drop under surface acoustic waves is comprehensively investigated and the contact angle hysteresis effects are considered, too. This paper reveals the effects of some control parameters such as wave amplitude and wave frequency on the dynamical behaviors of drop. For these purposes, a multiple-relaxation-time color-gradient model lattice Boltzmann method is developed. In these case studies, wave frequency and amplitude were in the ranges of 20–60 MHz and 0.5–2 nm, respectively. In addition, the density ratio of 1000, the...
Numerical analysis of droplet motion over a flat plate due to surface acoustic waves
, Article Microgravity Science and Technology ; Volume 32, Issue 4 , 2020 , Pages 647-660 ; Taeibi Rahni, M ; Shams Taleghani, S. A ; Sharif University of Technology
Springer
2020
Abstract
Micro-scale systems have gained considerable attention in recent years and a large amount of researches have been done in this field. In this study, the hydrodynamic interference of a droplet is comprehensively investigated under surface acoustic waves. This paper reveals the effects of some control parameters such as wave amplitude and wave frequency on the dynamical behavior of droplet. For these purposes, a two-dimensional multiple-relaxation-time color-gradient model lattice Boltzmann method is developed. This model is first validated by dynamical behaviors of a droplet subjected to shear flow. Moreover, displacement of a droplet affected by surface acoustic waves is comprehensively...
Phenomenological investigation of drop manipulation using surface acoustic waves
, Article Microgravity Science and Technology ; Volume 32, Issue 6 , 2020 , Pages 1147-1158 ; Shams Taleghani, A ; Taeibi Rahni, M ; Sharif University of Technology
Springer Science and Business Media B.V
2020
Abstract
This paper aims at the investigation of acoustic streaming produced by surface acoustic waves (SAWs) in a drop. Computational simulation of acoustofluidic phenomenon, using lattice Boltzmann method (LBM), presenting acoustic applications in flow control, and a relatively complete parametric study are the motivations of this work. For this purpose, a computational fluid dynamics modeling based on multi-relaxation time multi-component multiphase color gradient lattice Boltzmann method was used. The simulations were carried out at wave frequencies ranging from 20 MHz to 271 MHz and wave amplitudes ranging from 0.5 nm to about 350 nm. First, the non-dimensional form of Navier-Stokes equations...