Novel Design of Thermal-Via Configurations for Collector-Up HBTs

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Pei-Hsuan Lee ◽  
Hsien-Cheng Tseng ◽  
Jung-Hua Chou
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Heterojunction Bipolar Transistors ◽  
Heat Dissipation ◽  
Element Model ◽  
Bipolar Transistors ◽  
Maximum Temperature ◽  
3D Analysis ◽  
2D And 3D ◽  
Novel Design

We devise a finite-element model to analyze the thermal performance of collector-up (C-up) heterojunction bipolar transistors (HBTs) with a thermal-via configuration. A demonstration on the GaInP/GaAs C-up HBT is presented in this Brief, and the novelty of this work is that both 2D and 3D temperature-distribution analyses are performed. The 2D results indicate that the original thermal-via configuration can be reduced by 29%. Furthermore, the results show that the maximum temperature within the collector calculated from 3D analysis is lower than that from the 2D analysis. Based on the 3D analysis, it is revealed that the reported configuration can be reduced by 32%. Therefore, the C-up HBT with a compact thermal-via should be helpful for miniaturization of heat-dissipation packaging configurations within HBT-based high-power amplifiers.

Numerical study of heat transfer characteristics in positional wire and arc additive manufacturing

2020 ◽  
Vol 26 (9) ◽  
pp. 1627-1635
Author(s):  
Dongqing Yang ◽  
Jun Xiong ◽  
Rong Li
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Temperature Distribution ◽  
Finite Element Model ◽  
Heat Dissipation ◽  
Element Model ◽  
Heat Transfer Characteristics ◽  
Content Type ◽  
Thin Walled

Purpose This paper aims to fabricate inclined thin-walled components using positional wire and arc additive manufacturing (WAAM) and investigate the heat transfer characteristics of inclined thin-walled parts via finite element analysis method. Design/methodology/approach An inclined thin-walled part is fabricated in gas metal arc (GMA)-based additive manufacturing using a positional deposition approach in which the torch is set to be inclined with respect to the substrate surface. A three-dimensional finite element model is established to simulate the thermal process of the inclined component based on a general Goldak double ellipsoidal heat source and a combined heat dissipation model. Verification tests are performed based on thermal cycles of locations on the substrate and the molten pool size. Findings The simulated results are in agreement with experimental tests. It is shown that the dwell time between two adjacent layers greatly influences the number of the re-melting layers. The temperature distribution on both sides of the substrate is asymmetric, and the temperature peaks and temperature gradients of points in the same distance from the first deposition layer are different. Along the deposition path, the temperature distribution of the previous layer has a significant influence on the heat dissipation condition of the next layer. Originality/value The established finite element model is helpful to simulate and understand the heat transfer process of geometrical thin-walled components in WAAM.

scholarly journals Design Synchronous Generator Using Taguchi-Based Multi-Objective Optimization

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3337
Author(s):  
Ruiye Li ◽  
Peng Cheng ◽  
Yingyi Hong ◽  
Hai Lan ◽  
He Yin
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Optimization Algorithm ◽  
Continuous Optimization ◽  
Element Model ◽  
Optimization Method ◽  
Geometric Parameters ◽  
Maximum Temperature ◽  
Design Decision ◽  
Multi Objective

The extensive use of finite element models accurately simulates the temperature distribution of electrical machines. The simulation model can be quickly modified to reflect changes in design. However, the long runtime of the simulation prevents any direct application of the optimization algorithm. In this paper, research focused on improving efficiency with which expensive analysis (finite element method) is used in generator temperature distribution. A novel surrogate model based optimization method is presented. First, the Taguchi orthogonal array relates a series of stator geometric parameters as input and the temperatures of a generator as output by sampling the design decision space. A number of stator temperature designs were generated and analyzed using 3-D multi-physical field collaborative finite element model. A suitable shallow neural network was then selected and fitted to the available data to obtain a continuous optimization objective function. The accuracy of the function was verified using randomly generated geometric parameters to the extent that they were feasible. Finally, a multi-objective genetic optimization algorithm was applied in the function to reduce the average and maximum temperature of the machine simultaneously. As a result, when the Pareto front was compared with the initial data, these temperatures showed a significant decrease.

Multidisciplinary Placement Optimization of Heat Generating Semiconductor Logic Blocks

2008 ◽  
Author(s):  
Tohru Suwa ◽  
Hamid Hadim
Keyword(s):  
Temperature Distribution ◽  
Integrated Circuit ◽  
Element Model ◽  
Multidisciplinary Optimization ◽  
Maximum Temperature ◽  
Superposition Method ◽  
Design And Optimization ◽  
Placement Optimization ◽  
Optimization Methodology ◽  
Logic Blocks

A multidisciplinary optimization methodology for placement of heat generating semiconductor logic blocks on integrated circuit chips is presented. The methodology includes thermal and wiring length criteria, which are optimized simultaneously using the genetic algorithm. An effective thermal performance prediction methodology based on a superposition method is used to determine the temperature distribution on a silicon chip due to multiple heat generating logic blocks. Using the superposition method, the predicted temperature distribution in the silicon chip is obtained in much shorter time than with a detailed finite element model and with comparable accuracy. The main advantage of the present multidisciplinary design and optimization methodology is its ability to handle multiple design objectives simultaneously for optimized placement of heat generating logic blocks. Capabilities of the present methodology are demonstrated by applying it to several standard benchmarks. The multidisciplinary logic block placement optimization results indicate that the maximum temperature on a silicon chip can be reduced by up to 7.5°C, compared with the case in which only the wiring length is minimized.

Two-dimensional finite element model to study temperature distribution in peripheral regions of extended spherical human organs involving uniformly perfused tumors

2015 ◽  
Vol 08 (06) ◽  
pp. 1550074 ◽  
Author(s):  
Akshara Makrariya ◽  
Neeru Adlakha
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Finite Element Model ◽  
Metabolic Activity ◽  
Element Model ◽  
The Body ◽  
Tissue Response ◽  
Two Dimensional ◽  
Human Breast ◽  
Peripheral Regions

Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, human breast involving uniformly perfused tumor is investigated in this paper. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different layers of the breast. An elliptical-shaped tumor is assumed to be present in the dermis region of human breast. A finite element model is developed for a two-dimensional steady state case incorporating the important parameters like blood flow, metabolic activity and thermal conductivity. The triangular ring elements are employed to discretize the region. Appropriate boundary conditions are framed using biophysical conditions. The numerical results are used to study the effect of tumor on temperature distribution in the region.

Frictional heating of bearing materials tested in a hip joint wear simulator

1997 ◽  
Vol 211 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Z Lu ◽  
H McKellop
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frictional Heating ◽  
Element Model ◽  
Maximum Temperature ◽  
Zirconia Ceramic ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Surface Temperatures ◽  
Ability To Act

In a hip simulator wear test using bovine serum as a lubricant, the heat generated by ball-cup friction may cause precipitation of the proteins from the lubricant. The resultant accumulation of a solid layer of precipitated protein between the ball and cup could artificially protect the bearing surfaces from wear, in a manner that does not occur in vivo. Alternatively, the gradual depletion of the soluble proteins could interfere with their ability to act as boundary lubricants on the bearing surfaces, thereby artificially increasing the wear rate. Because the rate of protein precipitation may depend on the maximum temperature at the bearing surfaces during sliding, rather than the mean temperature of the bulk lubricant, this study determined the transient surface temperatures using an array of thermocouples embedded in acetabular cups of GUR 415 ultra-high molecular weight polyethylene (UHMWPE) and femoral balls of metal or ceramic, in conjunction with a finite element model of the temperature distribution. The prostheses were tested at one cycle/s under a Paul-type, physiological load profile with 2030 N maximum force, with the load cycle synchronized to the motion cycle. The steady state temperatures of the bulk lubricant were 38°C for the zirconia balls, 36°C for the cobalt-chromium and 33°C for the alumina. However, the corresponding surface temperatures of the polyethylene, calculated with the finite element model, were 99°C with zirconia ceramic, 60°C with cobalt-chromium alloy, and 45°C with alumina ceramic. The rank order of the surface temperatures corresponded to the relative amounts of protein that were precipitated in the test chambers during wear tests with these materials.

Finite element modeling and experimental validation of radio frequency heating (RFH) of curved laminated wood-based panels

Holzforschung ◽  
2014 ◽  
Vol 68 (6) ◽  
pp. 699-705 ◽  
Author(s):  
Jianhui Zhou ◽  
Chuanshuang Hu ◽  
Xiaoying Ma ◽  
Xingwei Guo
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Hot Pressing ◽  
Core Layer ◽  
Ambient Air ◽  
Element Model ◽  
Time Dependent ◽  
Heating Process ◽  
Radio Frequency Heating ◽  
Shape Effects

Abstract Thin medium-density fiberboards (MDF) are often used for the production of curved laminated furniture components by post-hot pressing with radiofrequency heating (RFH). Dimensional instability is one of the major quality problems of these products, and inappropriate heating process was discussed as the main reason for this. In the present study, a finite element model (FEM) was developed in this context, and the temperature distribution within laminated MDF panels was predicted aiming at optimizing the hot-pressing process with RFH. The time-dependent temperatures were collected by temperature sensing strips (TSS). The results agreed well with those obtained by the simulation model. Accordingly, the FEM developed here is well suited for predicting the heating behavior during hot pressing with RFH. The temperature distribution of the curved laminated MDF panels was not symmetric and not uniform because of curved shape effects and the heat convection between MDF panels and ambient air. The time-dependent temperatures of the top and bottom layers were lower than that of the core layer.

Temperature Field Numerical Simulation Analysis of 1000MW Ultra Supercritical Boiler’s Starting Water Separator

2012 ◽  
Vol 482-484 ◽  
pp. 651-654
Author(s):  
Na Li ◽  
Feng Ye
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Simulation Analysis ◽  
Element Model ◽  
Maximum Temperature ◽  
Safe Operation ◽  
Maximum Temperature Difference ◽  
Start Up ◽  
Water Separator ◽  
Distribution Laws

Aiming at the structural feature of starting water separator, a 3-D finite element model of temperature field is proposed. The starting water separator of a Ultra Supercritical Boiler(USB) has been numerically simulated by using of finite element soft ware Ansys. The boundary condition of the separator is determined. All of the working conditions are simulated. The results have the same distribution laws with the monitoring data of power plant. The maximum temperature difference between out wall and inner wall occurs in the temperature-rise period during the cold start-up, but the value between top wall and bottom wall is very lower. The simulation results can not only provide a basis for the thermal stress analysis and the life loss calculation but also provide rationalization proposal for the plant safe operation.

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