Development of Transient Thermal Models Based on Theoretical Analysis and Vehicle Test Data

2014 ◽  
Vol 7 (1) ◽  
pp. 188-195 ◽  
Author(s):  
Alaa El-Sharkawy ◽  
Ahmed Uddin
Keyword(s):  
Theoretical Analysis ◽  
Test Data ◽  
Thermal Models ◽  
Vehicle Test ◽  
Transient Thermal

scholarly journals Effects of operating and material parameters on the thermal characteristics of a wet clutch

2021 ◽  
Vol 13 (7) ◽  
pp. 168781402110341
Author(s):  
Zhigang Zhang ◽  
Ling Zou ◽  
Hang Liu ◽  
Yonglong Chen ◽  
Benzhu Zhang
Keyword(s):  
Heat Flux ◽  
Applied Pressure ◽  
Thermal Characteristics ◽  
Thermal Models ◽  
Material Parameters ◽  
Heat Transfer Theory ◽  
Friction Disk ◽  
Viscous Shear ◽  
Wet Clutch ◽  
Transient Thermal

Based on the frictional mechanism of a wet clutch, frictional models of wet clutch engagement were established using the modified Reynolds equation and the elastic contact model between frictional pairs. Then, the heat flux models for the viscous shear and asperity friction were built, and the two-dimensional transient thermal models for the separator plate, friction disk, and ATF heat convection model were deduced based on the heat transfer theory and conservation law of energy. Finally, the Runge–Kutta numerical method was used to solve the frictional and thermal models. The average temperature of the separator plate, friction disk, and ATF were calculated. The effects of operating and material parameters, such as applied pressure, initial angular velocity, friction lining permeability, surface combined roughness RMS, equivalent elastic modulus, and ATF flow, on the thermal characteristics of friction pairs and ATF during engagement, were studied. The simulation results show that the temperature characteristics of the separator plate, friction disk, and ATF depend mainly on the viscous shear and asperity friction heat flux, and that the operating and material parameters of the wet clutch also have significant impacts on the overall variation trend of the thermal characteristics of the separator plate, friction disk, and ATF.

Efficient Thermal Analysis of Lab-Grown Diamond Heat Spreaders

2021 ◽  
Author(s):  
Zihao Yuan ◽  
Tao Zhang ◽  
Jeroen Van Duren ◽  
Ayse K. Coskun
Keyword(s):  
Steady State ◽  
Real World ◽  
High Performance ◽  
Silicon Layer ◽  
Maximum Temperature ◽  
Cooling Performance ◽  
Thermal Models ◽  
Heat Spreaders ◽  
Transient Simulations ◽  
Transient Thermal

Abstract Lab-grown diamond heat spreaders are becoming attractive solutions compared to traditional copper heat spreaders due to their high thermal conductivity, the ability to directly bond them on silicon, and allow for an ultra-thin silicon layer. Researchers have developed various thermal models and prototypes of lab-grown diamond heat spreaders to evaluate their cooling performance and heat spreading ability. The majority of existing thermal models are built using finite-element method (FEM) based simulators such as COMSOL and ANSYS. However, such commercial simulators are computationally expensive and lead to long solution times along with large memory requirements. These limitations make commercial simulators unsuitable for evaluating numerous design alternatives or runtime scenarios for real-world high-performance processors. Because of this modeling challenge, none of the existing works have evaluated the thermal behavior of lab-grown diamond heat spreaders on real-world high-performance processors running realistic application benchmarks. Recently, we have developed a parallel compact thermal simulator, PACT, that is able to carry out fast and accurate steady-state and transient thermal simulations and can be extended to support emerging integration and cooling technologies. In this paper, we use PACT to evaluate the steady-state and transient cooling performance of lab-grown diamond heat spreaders against traditional copper heat spreaders on various real-world high-performance processors (e.g., Intel i7 6950X, IBM Power9, and PicoSoC). By using PACT with architectural performance and power simulators such as Sniper and McPAT, we are able to run transient simulations with realistic benchmarks. Simulation results show that lab-grown diamond heat spreaders achieve maximum temperature and thermal gradient reductions of up to 26.73 °C and 13.75 °C when compared to traditional copper heat spreaders, respectively. The maximum steady-state and transient simulation times of PACT for the real-world high-performance chips and realistic applications used in our experiments are 259 s and 22 min, respectively.

scholarly journals Extraction of Boundary Condition Independent Dynamic Compact Thermal Models of LEDs—A Delphi4LED Methodology

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1628 ◽  
Author(s):  
Robin Bornoff
Keyword(s):  
Boundary Condition ◽  
Ad Hoc ◽  
Thermal Response ◽  
System Level ◽  
Detailed Model ◽  
Thermal Models ◽  
Level Model ◽  
System Level Model ◽  
Transient Thermal ◽  
Transient Thermal Response

Multi-domain electro-thermal-optical models of LEDs are required so that their thermal and optical behavior may be predicted during a luminaire design process. Today, no standardized approach exists for the extraction of such models. Therefore, models are not readily provided by LED suppliers to end-users. This results in designers of LED-based luminaires wasting time on LED characterization and ad hoc model extraction themselves. The Delphi4LED project aims to address these deficiencies by identifying standardizable methodologies to extract both electro-optical and thermal compact models of LEDs that together can be used in a multi-domain simulation context. This article describes a methodology to extract compact thermal models of LEDs that are dynamic, in that they accommodate transient thermal effects, and are boundary condition-independent, in that their accuracy is independent of their thermal operating environment. Such models are achieved by first proposing an equivalent thermal nodal network topology. The thermal resistances and capacitances of that network are identified by means of optimization so that the transient thermal response of the network matches that of either an equivalent calibrated 3D thermal model or a transient thermal measurement of a physical sample. The accuracy of the thermal network is then verified by comparing the thermal compact model with a 3D detailed model, which predicts thermal responses within a 3D system-level model.

Initial Alignment Algorithm Study Based on Rotating Modulation and Kalman Filtering

2014 ◽  
Vol 513-517 ◽  
pp. 585-588 ◽  
Author(s):  
Zhi Wei Zhang ◽  
Hua Dong Sun
Keyword(s):  
Theoretical Analysis ◽  
Test Data ◽  
Kalman Filtering ◽  
Alignment Algorithm ◽  
Environmental Disturbance ◽  
Initial Alignment

Kalman filtering is used to restrain the influence of environmental disturbance to the initial alignment precision. Meanwhile, rotating modulation is utilized to reduce the influence of peg-top excursion and accelerometer zero deflection. The theoretical analysis and test data demonstrate that the proposed algorithm can improve the alignment precision by the combination of the two methods.

Design and Tests of Audio Directional System

2012 ◽  
Vol 198-199 ◽  
pp. 1047-1052
Author(s):  
Yang Zhang ◽  
Li Min Tao
Keyword(s):  
Theoretical Analysis ◽  
Light Beam ◽  
Test Data ◽  
Harmonic Distortion ◽  
Experimental System ◽  
The Self ◽  
Far Field ◽  
Sound Beam ◽  
System Components ◽  
Working Principle

Audio directional system is a new-style loudspeaker, which can project the sound beam onto a given region as light beam. In this paper, the basic working principle and the system components of audio directional system are proposed. The total harmonic distortion of the self-demodulated signal is analyzed based on “Berktay far-field solution”. Besides, this paper has designed the audio directional experimental system whose performances have been tested. The shortcomings of the self-demodulation theory are pointed out after the comparison between the test data and the theoretical analysis results.

scholarly journals Steady-State Steering Characteristics of Mathematical Model for Semitrailer Based on Variations in Camber Parameters

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yi Wei ◽  
Shuilong He ◽  
Enyong Xu ◽  
Genge Zhang ◽  
Rongjiang Tang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Test Data ◽  
Dynamic State ◽  
Model Parameters ◽  
Stability Factor ◽  
Camber Angle ◽  
Body Roll ◽  
Vehicle Test ◽  
Real Vehicle

To master the basic characteristics of steady-state cornering for a semitrailer, this paper summarises the current modelling methods for handling and stability and discusses their limitations. The classical linear mathematical model for a two-degree-of-freedom (DOF) handling and stability system is used to develop a new model. Analysis methods are proposed to introduce the influence of the camber angle and body roll into the model parameters. Thus, a mathematical model for the lateral stability of semitrailer with five DOFs is established. At the same time, a modified formula to calculate the stability factor of the semitrailer is developed with a MATLAB model to solve the dynamic state equation. The mathematical model, which considers the body roll and the changes in the camber angle caused by roll, compares the turning radius ratio and yaw rate as the evaluation index with the classical linear mathematical model of a two-DOF system. The vehicle parameters for three different types of semi-tractor trailers are used to calculate and compare two mathematical models for handling and stability using real vehicle test data. The results show that the new modelling and analysis method proposed in this paper has a high calculation accuracy and fast calculation speed, is clear and concise, and is consistent with the real vehicle test data. In addition, the accuracy of the new mathematical model for handling and stability and the improved stability factor are verified.

Compact Thermal and System Modeling of Chip-Scale Pyroelectric Infrared Imager

2007 ◽  
Author(s):  
Brian Smith ◽  
Cristina Amon
Keyword(s):  
System Modeling ◽  
Three Dimensional ◽  
System Model ◽  
Thermal Mass ◽  
Specific System ◽  
Thermal Models ◽  
Sensor Material ◽  
Infrared Imager ◽  
Transient Thermal ◽  
Thermal Phenomena

The performance of pyroelectric infrared detectors is directly related to the ability of the sensor material to retain infrared energy (heat) incident from the source and to react fast to changing heat loads. This leads to a complicated, three dimensional, transient thermal models when many detectors are assembled into an infrared focal plane array (IRFPA) for thermal imaging. Adjacent pixels and the underlying substrate conduct heat away from the sensor material and add thermal mass to the system. This paper describes efforts and drawbacks in deriving a system model to capture thermal phenomena in a candidate IRFPA. Of particular interest is the tradeoff between cumbersome finite element models (long solve time, complicated meshes) and a reduced-size RC network circuit model that is simple to solve and integrate with the electrical design but may not capture the full thermal behavior of the system adequately. The thermal models are cast in terms of the operating principles of pyroelectric devices to describe a full electrical-thermal system model that adapts existing literature in the field to the specific system described in this work.

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