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Three-stage Nonlinear thermal model for Microspeakers in Mobile Phones

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Sound & Vibration 2018年第5期52卷 28-33页

作者： Zhiliang Zhang Yong Shen Jie Xia Yuchen Shen Institute of Acoustics Key Laboratory of Modern Acoustics of Ministry of EducationNanjing UniversityNanjing210093China

Since microspeakers are widely used in mobile phones,high power is usually applied to obtain sufficient output sound ***,the electric power is almost converted into heat,leading to the thermal problem in *** with large loudspeaker,microspeakers are smaller and the under yoke is relatively closed,causing the heat transfer more *** this study,a three-stage nonlinear thermal model was proposed for analyzing the thermal behavior in *** inside air is a buffer area between the voice coil and magnet,and modeled as a middle stage of the heat *** forced convection is still significant in microspeakers while the eddy current can be *** order to obtain the thermal parameters of the model,a corresponding parameter identification method was put *** basic linear parameters and forced convection parameters were all obtained by measuring and fitting the temperature curves of voice coil at different single tones.A series of experiments were conducted to verify the proposed model and parameter identification method,and the results showed good aggrement between the measured and predicted temperature curves for different input *** proposed model was valid and accurate,and may be helpful for the design and application of microspeakers.

关键词： Microspeakers heat transfer thermal model mobile phones

Rate-equation-based VCSEL thermal model and simulation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第12期7卷 1968-1972页

作者： LIU Jie CHEN Wen-lu LI Yu-quan Jiangnan Institute of Computing Technology Wuxi 214083 China Institute of Communications Engineering PLA Univ. of Sci. ＆ Tech.. Nanjing 210007 China

In this paper, we present a simple thermal model of Vertical-Cavity Surface-Emitting Laser （VCSEL） light-current （L1） characteristics based on the rate-equation. The model can be implemented in conventional SPICE-like circuit simulators, including HSPICE, and be used to simulate the key features of VCSEL. The results compare favorably with experimental data from a device reported in the literature. The simple empirical model is especially suitable for Computer Aided Design （CAD）, and greatly simplifies the design of optical communication systems.

关键词： Carrier leakage Vertical-Cavity Surface-Emitting Lasers (VCSELs) Rate-equation thermal model SPICE simulation

Four-parameter Real-time thermal model for DRY DCTs

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Four-parameter Real-time Thermal Model for DRY DCTs

thermal modeling optimization and experimental validation for a single concentrator solar cell system with a heat sink

2019中国汽车工程学会年会

作者： Qiu Zhiyang Zheng Zhilin Charlie Miao Dongxiao Chen Li State Key Laboratory of Ocean Engineering Institution of Power Plant and AutomationShanghai Jiao Tong University

Excessive temperatures tend to occur in dual clutch transmissions（DCTs） due to large amount of friction heat generated in the compact space,but seriously deteriorate shift quality and even reduce *** order to accurately obtain the DCT temperature in real-time,a four-parameter model is proposed to modify the previously studied static two-parameter model by introducing two dynamic *** to the deduction of energy balance equation based on a one-dimension assumption,the two dynamic coefficients are found to inherently change along with the friction heat and ambient *** changing rates constitute a four-parameter *** new model is verified by dynamometer experiments,which show higher accuracy and better adaptability to working conditions than the static two-parameter model.

关键词： dry dual clutch transmission thermal model real-time model four-parameter dynamometer experiment

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Chinese Physics B 2013年第8期22卷 456-461页

作者：崔敏陈诺夫邓金祥刘立英 College of Applied Sciences Beijing University of Technology New and Renewable Energy of Beijing Key Laboratory North China Electric Power University

A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7 ~C and 36.3 ~C respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37 ℃-38 ℃ and 35 ℃-36 ℃respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells.

关键词： heat sink concentrator solar cell thermal model cooling

Autoregressive neural networks with exogenous variables for indoor temperature prediction in buildings

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Building Simulation 2021年第1期14卷 165-178页

作者： Benoit Delcroix Jérôme Le Ny Michel Bernier Muhammad Azam Bingrui Qu Jean-Simon Venne Department of Mechanical Engineering Polytechnique Montréal2500 Chemin de PolytechniqueMontréalQCH3T 1J4Canada Department of Electrical Engineering and GERAD Polytechnique Montréal2500 Chemin de PolytechniqueMontréalQCH3T 1J4Canada Smart Building Lab BrainBox AIMontréalQCCanada

thermal models of buildings are helpful to forecast their energy use and to enhance the control of their mechanical ***,these models are building-specific and require a tedious,error-prone and time-consuming development effort relying on skilled building energy *** to white-box and gray-box models,data-driven(black-box)models require less development time and a minimal amount of information about the building *** this paper,autoregressive neural network models are compared to gray-box and black-box linear models to simulate indoor *** models are trained,validated and compared to actual experimental data obtained for an existing commercial building in Montreal(QC,Canada)equipped with roof top units for air *** show that neural networks mimic more accurately the thermal behavior of the building when limited information is available,compared to gray-box and black-box linear *** gray-box model does not perform adequately due to its under-parameterized nature,while the linear models cannot capture non-linear phenomena such as radiative heat transfer and ***,the neural network models outperform the alternative models in the presented application,reaching a coefficient of determination R2 up to 0.824 and a root mean square error down to 1.11℃,including the error propagation over time for a 1-week period with a 5-minute *** considering a 50-hour time horizon,the best neural networks reach a much lower root mean square error of around 0.6℃,which is suitable for applications such as model predictive control.

关键词： thermal model building simulation experimental validation multi-layer perceptron linear vs.non-linear black-box vs.gray-box

Quantum“contact”friction:The contribution of kinetic friction coefficient from thermal fluctuations

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Friction 2023年第10期11卷 1877-1894页

作者： Rasoul KHEIRI Skolkovo Institute of Science and Technology Moscow 121205Russia

A thermal model of kinetic friction is assigned to a classical loaded particle moving on a fluctuating smooth surface.A sinusoidal wave resembles surface fluctuations with a relaxation *** Hamiltonian is approximated to the mean energy of the wave describing a system of Harmonic *** quantization of amplitudes yields in terms of annihilation and creation operators multiplied by a quantum ***,we consider acoustic dispersion relation and evaluate the friction coefficient from the force autocorrelation *** the sliding particle remains classical describing a nano-particle or a tip with negligible quantum effects like tunneling or delocalization in the wave function,the quantized model of the surface fluctuations results in the temperature dependence of the kinetic friction *** follows an asymptotic value for higher temperatures and supper-slipperiness at low temperatures.

关键词： kinetic friction coefficient fluctuation-dissipation quantum friction thermal model phonon

Measurement of thermal boundary conductance between metal and dielectric materials using femtosecond laser transient thermoreflectance technique

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Science China(Technological Sciences) 2012年第4期55卷 1044-1049页

作者： ZHANG ChungWei BI KeDong WANG JianLi NI ZhongHua CHEN YunFei JiangSu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments School of Mechanical EngineeringSoutheast UniversityNanjing 211189China

The thermal boundary conductance of Al/SiO2, Al/Si, Au/SiO2, and Au/Si are measured by a femtosecond laser transient thermoreflectance technique. The distinct differences of the interfacial thermal conductance between these samples are observed. For the same metal film, the thermal boundary conductance between metal and substrate decreases with the thermal conductivity of the substrate. The measured results are explained with the phonon diffusion mismatch model by introducing a phonon transmission coefficient across the interface.

关键词： femtosecond transient thermoreflectance technique thermal boundary conductance thermal model phonon transimis- sion probability

Hybrid modeling for Soft Sensing of Molten Steel Temperature in LF

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Journal of Iron and Steel Research International 2009年第4期16卷 1-6页

作者： TIAN Hui-xin MAO Zhi-zhong WANG An-na School of Electrical and Automation Engineering Tianjin Polytechnic University Tianjin 300160 China School of Information Science and Engineering Northeastern University Shenyang 110004 Liaoning China Key Laboratory of Integrated Automation of Process Industry of Ministry of Education NortheasternUniversity Shenyang 110004 Liaoning China

Aiming at the limitations of traditional thermal model and intelligent model, a new hybrid model is established for soft sensing of the molten steel temperature in LF. Firstly, a thermal model based on energy conservation is described; and then, an improved intelligent model based on process data is presented by ensemble ELM （extreme learning machine） for predicting the molten steel temperature in LF. Secondly, the self-adaptive data fusion is pro- posed as a hybrid modeling method to combine the thermal model with the intelligent model. The new hybrid model could complement mutual advantage of two models by combination. It can overcome the shortcoming of parameters obtained on-line hardly in a thermal model and the disadvantage of lacking the analysis of ladle furnace metallurgical process in an intelligent model. The new hybrid model is applied to a 300 t LF in Baoshan Iron and Steel Co Ltd for predicting the molten steel temperature. The experiments demonstrate that the hybrid model has good generalization performance and high accuracy.

关键词： ladle furnace hybrid modeling soft sensing thermal model data fusion

Performance and Optimization for a Ground-Coupled Liquid Loop Heat Recovery Ventilation System

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Journal of Donghua University(English Edition) 2007年第6期24卷 749-755页

作者：周亚素 Per FAHLEN Torbjrn LINDHOLM Department of Building Environment and Equipment Engineering Donghua University Department of Building Services Engineering Chalmers University of TechnologySE-412 96GothenburgSweden

Ground-coupled heat pumps(GCHP)are commonly used in residential heating *** mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is *** new recharging system can be used in three operational *** this paper,a ground-coupled heat recovery ventilation(HRV)model is discussed.A thermal model is set up to find the optimal brine flow rate and heat transfer allocation ratio between exhaust and supply coils for maximum heat recovery *** to the conventional liquid-loop HRV systems,the brine temperature entering the exhaust coil never goes blow zero(0℃),and hence defrosting is needless in the ground-coupled HRV *** can make the ground-coupled HRV system over 20% more efficient than a conventional HRV system at low outdoor temperatures.

关键词： a ground-coupled HRV system thermal model heat recovery efficiency coils allocation ratio brine flow rate