Browsing by Author "Chiou, Hong-Wen"

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Learning Based Mesh Generation for Thermal Simulation in Handheld Devices with Variable Power Consumption
(2019-01-01)
Lo, Wen-Sheng
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Chiou, Hong-Wen
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Hsu, Shih-Chieh
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Lee, Yu-Min
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Cheng, Liang-Chia
This work utilizes machine learning techniques to achieve learning based mesh generation for the thermal simulator. In the learning stage, first, we generate many power value sets of application processors and apply the superposition technique to obtain the temperature raw data of material blocks. We, then, use these thermal data and several defined thermal gradient ranges to obtain different appropriate mesh-size sets of material blocks for each power value set. We construct the regressions that are capable of predicting targets as a supervised learning task, and the architecture of regression model includes seven hidden layers. After the learning stage, we integrate the learning based mesh decision engine into a developed system-level thermal simulator, which is built by the finite difference method. The experimental results show that the temperature profiles of the handheld device calculated by the developed thermal simulator with learning based mesh generation fits the results obtained by a commercial tool pretty well with less runtime usages. Moreover, the learning based mesh decision engine is much more efficient than the artificial mesh decision.
Multi-Angle Bended Heat Pipe Design Using X-Architecture Routing with Dynamic Thermal Weight on Mobile Devices
(2019-01-01)
Hsiao, Hsuan-Hsuan
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Chiou, Hong-Wen
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Lee, Yu-Min
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交大名義發表
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電信工程研究所
Heat pipe is an effective passive cooling technique for mobile devices. This work builds a multi-angle bended heat pipe thermal model and presents an X-architecture routing engine guided by developed dynamic thermal weights to construct the heat pipe path for reducing the operating temperatures of a smartphone. Compared with a commercial tool, the error of the thermal model is only 4.79%. The routing engine can efficiently reduce the operating temperatures of application processors at least 13.20% in smartphones.
Phone-nomenon: A System-Level Thermal Simulator for Handheld Devices
(2019-01-01)
Chiou, Hong-Wen
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Lee, Yu-Min
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Shiau, Shin-Yu
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Pan, Chi-Wen
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Chen, Tai-Yu
This work presents a system-level thermal simulator, Phone-nomenon, to predict the thermal behavior of smartphone. First, we study the nonlinearity of internal and external heat transfer mechanisms and propose a compact thermal model. After that, we develop an iterative framework to handle the nonlinearity. Compared with a commercial tool, ANSYS Icepak, Phonenomenon can achieve two and three orders of magnitude speedup with 3:58% maximum error and 1:72 degrees C di fference for steady-state and transient-state simulations, respectively. Meanwhile, Phone-nomenon also fits the measured data of a built thermal test vehicle pretty well.
Thermal Modeling and Design on Smartphones with Heat Pipe Cooling Technique
(2017-01-01)
Chiou, Hong-Wen
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Lee, Yu-Min
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Hsiao, Hsuan-Hsuan
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Cheng, Liang-Chia
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電信工程研究所
While the performance of smartphones becomes much higher, the application processor consumes considerable power. Thus, it is hard to meet thermal constraints by using conventional cooling techniques. Fortunately, since heat pipes can efficiently transfer the thermal energy from hot regions to cool regions, temperatures in hot regions can be reduced greatly. Hence, in the past three years, the heat pipe cooling techniques have been applied to smartphones by industries. However, although the time-consuming commercial simulation tools, such as ANSYS Fluent, can provide accurate thermal maps, they may lead to inefficiency during design stages. Besides, the compact thermal model for bended heat pipes is still underdeveloped. Therefore, efficient thermal simulation for smartphones with bended heat pipes should be developed for the design stage. Furthermore, the routing of bended heat pipe should be optimized to obtain more thermal energy transfer. This work presents a compact thermal model for bended heat pipes and an efficient thermal simulator for smartphones. Moreover, with inconsistent maze routing and dynamic thermal weight assignment, a thermal-driven routing algorithm is proposed for optimizing the design of bended heat pipe. Compared with ANSYS Fluent, the thermal simulation with bended heat pipe thermal model can achieve at least three orders of magnitude speedup with only 3.58% maximum error for all chips. The proposed heat pipe routing algorithm can reduce at least 10.86% of the maximum temperatures for application processors.