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Finite element methods are often used to simulate surface acoustic wave (SAW) resonators. Usually, only bi-dimensional or periodic models are practical on long resonators. The hierarchical cascading method proposed in 2016 uses the repetitive structure of a SAW resonator to obtain a computation time proportional to the logarithm of the electrode number. Using this approach, a full 3D simulation of...
The normal way to simulate SAW resonators is to use a phenomenological model like coupling of modes or P matrix. Numerical methods can also be used but are very costly in computing resources. Models based on combination of finite elements and boundary elements models are a possible approach but are mostly limited two dimensional models. Also, they are less versatile than models using only finite elements...
Cochlear implants (CI) provide opportunities for people with profound hearing impairment to recover partial hearing. An acoustic CI model based on specific stimulating strategy can be used to study sounds processed in CI, and allows test subjects with normal hearing to evaluate stimulating strategy performance. However, there is still a significant performance difference between hearing test results...
Capacitive Micromachined Ultrasonic Transducer (CMUT) is a new type of ultrasound wave generator and detector. Analytical method is intuitive to understand the mechanism and physical effects through modeling of CMUT. To optimize the design procedures of CMUT membrane undergoing large deflection, a new analytical model with the consideration of the lateral force using Von Kármán equations is proposed...
Application of finite element methods (FEM) to the simulation of SAW devices has been constrained by the large number of degrees-of-freedom required, resulting in large memory usage and long computation times. Here, we propose a hierarchical cascading approach which takes advantage of the periodic structure typical of SAW devices. In this approach, each unique electrode period is modeled and simulated...
Although bipolar nerve cuff electrodes (NCEs) are used in clinical neurostimulation therapies (e.g., epilepsy, obstructive sleep apnea), the use of this electrode as part of a closed-up controlled system is very limited. The literature points to high noise content (i.e., poor signal-to-noise ratio, SNR) as the primary reason for not using bipolar NCEs to record neural activity. In fact, over the past...
The paper considers a focusing piezoelectric transducer in the form of a spherical segment with technological hole in the center and with separated electrodes. This transducer is designed to generate high-intensity ultrasonic fields with controllable characteristics in the focal spot in the external acoustic medium. In order to enhance the efficiency of the acoustic wave excitation, porous piezoceramics...
We consider a problem of waves propagation in a multi-layered piezoelectric substrate under a periodic electrode grating utilizing a full-FEM approach for a unit cell with periodic boundary conditions. The perfectly matched layer is employed in order to truncate the computational domain. The simulations are done for the structures containing one- and two-layered piezoelectric substrates. The COM parameters...
Mouse models are widely used in studies of various forms of transcranial electric stimulation (TES). However, there is limited knowledge of the electric field distribution induced by TES in mice, and computational models to estimate this distribution are lacking. This study examines the electric field and current density distribution in the mouse brain induced by TES. We created a high-resolution...
This research work is mainly focused on modeling and simulation of Electrical Capacitance Tomography (ECT) sensor which comprises of 12 electrodes that are fabricated externally. The arrangement of electrodes is in the form of multi-plane (i.e. single and twin-plane electrodes). The Finite Element Method (FEM) can be utilized to simulate and compute capacitance values. This simulation method can provide...
Finite Element Analysis (FEA) of CMUT arrays offers flexibility with membrane geometry, but it can become computationally expensive as the transducer array and fluidic space increases in size. The objective is to combine the modeling flexibility of 3D FEA with the computational effectiveness of 2D numerical methods to analyze and design CMUT arrays with arbitrary membrane shapes. Effective numerical...
This paper presents two numerical evaluation schemes to simulate the dielectric breakdown phenomena for the capacitive micro-arrayed ultrasonic transducers (CMUT). The performance of dielectric strength was investigated using a commercial finite element method (FEM) software package of ANSYS. The electro-mechanical model was established using the ANSYS parametric design language (APDL) technique....
A novel dynamical model for a single cell electric double-layer capacitor is proposed. The model was derived from a distributed-parameter electrochemical model, first reformulated and then approximated to reduce its order. Finite dimension approximations were obtained by applying finite differences, finite element and differential quadrature semidiscretization methods. The best approach was obtained...
The goal of this digest is to develop a quantitative understanding about the shape and the volume of tissue activated (VTA) and stimulation site by deep brain stimulation (DBS) in deep brain area like subthalamic nucleus (STN) to improve neural stimulation. Current steering approach has been used in cochlear implant systems. In this digest, a novel current steering approach is applied to deep brain...
In this paper, we propose a new transcranial direct current stimulation (tDCS) system which uses multiple electrode arrays. Once a target location inside a human brain is selected, optimal injection current at each electrode is determined by solving a constrained optimization problem, of which the objective function is evaluated by 3D finite element method (FEM) adopting the superposition principle...
The initial filamentary streamers in liquid dielectrics drastically changes by the tip curvature of the electrode and the applied voltage. In this paper to get the non uniform field a sphere-to-plane electrodes configuration is used. Also, an immersed air bubble adjacent to the sphere electrode is presented, to obtain the sharp tip, after the air bubble compressed against the sphere electrode i.e...
Radiofrequency ablation has been used to treat some types of cardiac arrhythmias. We have previously proposed an ARMAX model (non structural) to estimate the temperature in the tissue during ablation. Computer modeling has allowed us to study the temperature distribution by means of solving numerically theoretical models based on partial differential equations, which represent physical phenomena....
Radiofrequency (RF) ablation uses RF current to heat and kill cancer applied via an electrode inserted under image-guidance, and is in clinical use for tumors in liver, lung kidney, and bone. Mathematical models are frequently used to determine tissue temperature during RF ablation, but most prior models do not include accurate implementation of power control algorithms as are used in clinical devices...
Electroconvulsive therapy (ECT) is the most effective treatment for severe depressive disorder, and yet the mechanisms of its therapeutic effects remain largely unknown. A novel computational model is presented in this study to simulate and investigate direct cortical excitation caused by bitemporal electroconvulsive therapy (BT ECT), using a finite element model (FEM) of the human head. The skull...
The simulation of electrical activity in the heart, such as normal and abnormal ventricular rhythms and ischemia, utilize computational methods that rely on an underlying geometric model, or polygonal mesh of cardiac tissues and boundaries. Because of the complex shape of many biological structures, it is often difficult to create meshes that conform to the boundaries between distinct regions. The...
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