Coupled thermal‐acoustic simulation results with temperature‐dependent tissue parameters for therapeutic ultrasound

1998 ◽  
Vol 104 (3) ◽  
pp. 1844-1844 ◽  
Author(s):  
Ibrahim M. Hallaj ◽  
Robin O. Cleveland ◽  
Ronald A. Roy ◽  
R. Glynn Holt
Keyword(s):  
Therapeutic Ultrasound ◽  
Temperature Dependent ◽  
Acoustic Simulation ◽  
Simulation Results

Mushy Zone Resolidification in a Temperature Gradient in Multiphase and Multicomponent Alloys

2014 ◽  
Vol 790-791 ◽  
pp. 109-114 ◽  
Author(s):  
Andrea Löffler ◽  
Markus Rettenmayr
Keyword(s):  
Temperature Gradient ◽  
Mushy Zone ◽  
Liquid Fraction ◽  
Peritectic Temperature ◽  
Temperature Dependent ◽  
Full Agreement ◽  
Multiphase Alloys ◽  
Multiphase Equilibria ◽  
Simulation Results ◽  
Annealing Experiments

A model for simulating mushy zone resolidification in a temperature gradient is presented. For describing macroscopic mass transport in the liquid phase in the mushy zone, an extended diffusion equation is solved numerically using the Finite Difference Method. Temperature dependent local equilibria at each position in the mushy zone are calculated using the thermodynamic software package ChemApp. The resolidification model treats multicomponent alloying systems and accounts for multiphase equilibria. Simulation results for peritectic Cu-40wt%Al and eutectic Al-5wt%Si-1wt%Mg alloys are compared with microstructures from temperature gradient annealing experiments. It is shown that the model is well suited to predict mushy zone resolidification in multicomponent and multiphase alloys. The predicted evolution of the liquid fraction is qualitatively in full agreement with the observed microstructures, including local remelting at the peritectic temperature prior to resolidification, an effect that was first predicted by the model and confirmed by the experiments.

scholarly journals Detection, Integration, and Optimization of Acoustic Field Simulation in the Closed Space

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Siming Meng ◽  
Ge Lin ◽  
Xiaoyan Liang
Keyword(s):  
Wave Propagation ◽  
Acoustic Field ◽  
Geometric Analysis ◽  
Noise Pollution ◽  
Closed Space ◽  
Acoustic Simulation ◽  
Field Simulation ◽  
Sound Barrier ◽  
Simulation Results ◽  
Acoustic Field Simulation

Noise pollution in the closed space such as railway carriage is an important problem because the noise pollution seriously affects comfort and health of people in the closed space. We propose the method to detection, integration, and optimization of acoustic field simulation in the closed space. First, we analyze the acoustic field distribution in the virtual 3D close space. We use harmonic sound wave propagation in the closed space and present the distribution according to geometric analysis. Second, we introduce Delaunay triangulation and k-means clustering into visualization to form the quiet zone and show it in 3D perspective. Our method used acoustic simulation to develop the sound barrier system. The simulation results show that our method can improve the analysis of the noise problem in the closed space.

scholarly journals An Airborne Offner Imaging Hyperspectrometer with Radially-Fastened Primary Elements

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3411 ◽  
Author(s):  
Nikolay Kazanskiy ◽  
Nikolay Ivliev ◽  
Vladimir Podlipnov ◽  
Roman Skidanov
Keyword(s):  
Optical Characteristics ◽  
Space Vehicles ◽  
Optical Scheme ◽  
Temperature Dependent ◽  
Small Space ◽  
Optical Components ◽  
Temperature Range ◽  
Optical Experiment ◽  
Simulation Results ◽  
Cold Chamber

We propose a new layout for the Offner imaging hyperspectrometer that is utilized onboard small space vehicles. The layout is based on a method of adjusting the adaptive temperature-dependent optical scheme by moving just two coaxial optical components located inside the hyperspectrometer. We present the results of modeling for a temperature range of −40 to +45 °C and an optical experiment using a heat and cold chamber for the range of 12 to 40 °C, proving the basic functionality of the proposed layout. Based on simulation results, the new layout is supposed to allow the hyperspectrometer to operate in a temperature range of −40 to +45 °C without its optical characteristics deteriorating, thus making it suitable for work onboard space or stratospheric vehicles.

A High Order Curvature-Compensated Bandgap Voltage Reference with a Novel Error Amplifier

2017 ◽  
Vol 26 (09) ◽  
pp. 1750127 ◽  
Author(s):  
Gongyuan Zhao ◽  
Mao Ye ◽  
Yiqiang Zhao ◽  
Kai Hu ◽  
Ruishan Xin
Keyword(s):  
Monte Carlo Simulation ◽  
Power Supply ◽  
Supply Voltage ◽  
High Order ◽  
Cmos Process ◽  
Voltage Reference ◽  
Temperature Dependent ◽  
Error Amplifier ◽  
Bandgap Voltage Reference ◽  
Simulation Results

This paper presents a bandgap voltage reference (BGR), utilizing high order curvature-compensated technique with the temperature dependent resistor. Based on an improved error amplifier, [Formula: see text]80[Formula: see text]dB power supply rejection (PSR) @1[Formula: see text]kHz is achieved without additional complicated circuits. The circuit is fabricated in a standard [Formula: see text]m CMOS process, consuming 50[Formula: see text][Formula: see text]A at 25[Formula: see text]C with a supply voltage of 3.3[Formula: see text]V. Simulation results show that the proposed BGR can achieve a temperature coefficient as low as 1.18[Formula: see text]ppm/[Formula: see text]C over the temperature range from [Formula: see text]C to 120[Formula: see text]C. Monte Carlo simulation and Experimental Results validate the design.

The Bending Behaviour Characterisation of Thermoplastic Prepregs and its Influence on the Wrinkling

2015 ◽  
Vol 651-653 ◽  
pp. 356-362 ◽  
Author(s):  
Biao Liang ◽  
Nahiene Hamila ◽  
Philippe Boisse
Keyword(s):  
Room Temperature ◽  
Bending Test ◽  
Viscous Effect ◽  
Temperature Dependent ◽  
Bending Properties ◽  
Influence Of Temperature ◽  
Simulation Results ◽  
Thermoforming Process ◽  
Deformation Modes ◽  
Bending Behaviour

The bending deformation of thermoplastic prepregs is one of the key deformation modes in the thermoforming due to its crucial role in the wrinkling occurrence. The influence of temperature is of main importance because the viscous effect of resin is temperature dependent and prepregs thermoforming is usually performed closed to resin’s melting point. The currently available bending test devices are not adapted for thermoplastic prepregs since these devices can only be operated at room temperature. To solve this problem, a new cantilever test with an optical measuring performed in an environmental chamber is proposed. The bending properties of PPS-carbon satin prepregs are measured at a series of high temperatures. It’s shown that the bending stiffness of the fore-mentioned pepregs is strongly affected by the temperature and shows a non-linear bending behaviour. The measured bending properties are used to simulate a thermoforming process. The influence of bending properties on the simulation results, especially to the wrinkling is presented as well.

scholarly journals Analysis on Structural Stress of 64 × 64 InSb IRFPAs with Temperature Dependent Elastic Underfill

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Liwen Zhang ◽  
Wei Tian ◽  
Qingduan Meng ◽  
Mengfang Sun ◽  
Na Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Maximum Stress ◽  
Elastic Model ◽  
Structural Stress ◽  
Temperature Dependent ◽  
Stress Maximum ◽  
Maximal Stress ◽  
Indium Bump ◽  
Simulation Results ◽  
Short Time

To improve the reliability of InSb IRFPAs, underfill has usually been filled between InSb chip and Si ROIC. Around the glass transition temperature, underfill shows viscoelasticity, yet, far below it, which shows apparently temperature dependent mechanical properties. Basing on the temperature dependent elastic model of underfill, firstly a small format array of8×8elements InSb IRFPAs is investigated by changing indium bump diameters and heights; simulated results show that the maximum stress in InSb chip has nothing to do with underfill height and is dependent on indium bump diameter; the varying tendency is just like the horizontally extended letter U. When indium bump diameter is set to 24 μm with height 21 μm, the maximal stress in InSb chip reaches minimum. To learn the stress in64×64elements in short time, with the above optimal structure, InSb IRFPAs array scale is doubled once again from8×8to64×64elements. Simulation results show that the stress maximum in InSb chip is strongly determined by arrays format and increases with array scale; yet, the stress maximum in Si ROIC almost keeps constant and is independent on array sizes; besides, the largest stress locates in InSb chip, and the stress distribution in InSb chip is uniform.

scholarly journals Temperature dependent analytical model for submicron GaAs-MESFET

2021 ◽  
Vol 10 (3) ◽  
pp. 1271-1282
Author(s):  
Mohamed Djouder ◽  
Arezki Benfdila ◽  
Ahcene Lakhlef
Keyword(s):  
Analytical Model ◽  
Temperature Dependent ◽  
Gaas Mesfet ◽  
Voltage Variation ◽  
Proposed Model ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Simulation Results ◽  
Parameter Values ◽  
Good Agreement

MESFET are used in circuitsof gigahertz frequencies as they are based on gallium arsenide (GaAs) having electron mobility six times higher than that of silicon. An analytical model simulating different device current-voltage characteristics, i.e., output conductance and output transconductance of a 0.3μm gate MESFET with temperature dependence is proposed. The model is validated by comparing the results of the proposed model and those of the numerical simulation. The parameter values are computed using an intrinsic MESFET of two-dimensional geometry. In this work, the distribution of different output loads for varied applied voltages is considered. Simulation results obtainedunder temperature variation effectsfor load distribution and applied driven voltage variation are considered. The RMS and average errors between the different models and GaAs MESFET simulations are calculated to evidence the proposed model accuracy. This was demonstrated by a good agreement between the proposed model and the simulation results, which are found in good agreement. The simulation results obtained under temperature variations were discussed and found to complement those obtained in the literature. This clarifies the relevance of the suggested model analytical.

Computational Modeling of Homogeneous Nucleation and Particle Growth During Chemical Vapor Deposition of Silicon Films from Silane Plasmas

2002 ◽  
Vol 715 ◽  
Author(s):  
S Warthesen ◽  
U Bhandarkar ◽  
S Girshick ◽  
U Kortshagen
Keyword(s):  
Plasma Chemistry ◽  
Chemical Vapor ◽  
Electron Attachment ◽  
Particle Growth ◽  
Nucleation And Growth ◽  
Gas Temperature ◽  
New Materials ◽  
Temperature Dependent ◽  
Excited Species ◽  
Simulation Results

AbstractWe have been developing a model to study the nucleation and growth of particles in silane plasmas. Presently we are experimenting with parameters that could potentially be important. It has been found that an increase in the heavy species gas temperature leads to a delay in the nucleation of particles in low pressure silane plasmas. This effect could be useful in tailoring processes for the manufacture of new materials such as polymorphous silicon. We have made an effort to study this effect using a plasma chemistry model. The model includes gas temperature dependent electron attachment and vibrational relaxation of excited species with a view to study their importance in relation to the gas temperature. Preliminary simulation results predict that these two processes do not contribute substantially to slowing the nucleation process when the gas temperature is increased. Extra efforts must be made to study this potentially important effect.

Numerical and Experimental Study of Strain Rate Effects in Laser Forming

2000 ◽  
Vol 122 (3) ◽  
pp. 445-451 ◽  
Author(s):  
Wenchuan Li ◽  
Y. Lawrence Yao
Keyword(s):  
Strain Rate ◽  
Material Properties ◽  
Peak Temperature ◽  
Laser Forming ◽  
Temperature Dependent ◽  
Strain Rate Effects ◽  
Temperature Method ◽  
Rate Effects ◽  
Forming Efficiency ◽  
Simulation Results

Experimental investigation and numerical simulation of the influence of the strain rate in laser forming are presented. To isolate and effectively study the strain rate effects, which are temperature dependent, a “constant peak temperature” method is developed with the aid of numerical modeling and solution. Under the condition of the constant peak temperature, the effects of strain rate on forming efficiency, residual stress and hardness of the formed parts are studied both experimentally and numerically. In the numerical model, the temperature dependence and strain-rate dependence of the flow stress and other material properties are considered. The simulation results are consistent with the experimental observations. [S1087-1357(00)01004-2]

Modeling and Experimental Studies of Particles Velocity and Temperature in Plasma Spraying Processes

1997 ◽  
Author(s):  
A.Ph. Ilyuschenko ◽  
V.A. Okovity ◽  
S.P. Kundas ◽  
A.N. Kuz’menkov
Keyword(s):  
Particle Temperature ◽  
Experimental Studies ◽  
Al2o3 Particle ◽  
Temperature Dependent ◽  
Program Complex ◽  
Real Process ◽  
Process Error ◽  
Simulation Results ◽  
Temperature Dependent Properties ◽  
Intensity Radiation

Abstract Mathematical and computer models of movement and heating of particles in low pressure conditions are developed. The mathematical models are based on the molecular-kinetics theory of gases. A program complex for computer realization of models is developed. It contains a built-in data base of temperature dependent properties of substances, system of processing and graphic visualization of simulation results. For verification of the developed models, computer simulation and experimental measurments of Al2O3 particle temperature and velocity are conducted. These materials were sprayed in Plasma-Technik equipment at pressure 60 mBar in argon. Particle velocity was measured with a special optical device, particle temperature was defined by intensity radiation method. It was established that the developed models are adequate to real process (error of 5-8 %) and may be used for study and improvement of VPS processes.

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