Fast Calculation Method of Energy Flow for Combined Electro-Thermal System and Its Application

In recent years, Combined electro-thermal system has developed rapidly. In order to provide the initial data for the analysis of the combined electro-thermal system, a practical energy flow calculation method for the combined electro-thermal system is proposed in this paper. Based on the detailed analysis of the topology structure of the heating network and its hydraulic and thermodynamic model, the forward-backward sweep method for the heat flow of the heating network is established, which is more suitable for the actual radial heating network. The electric and thermal coupling model for heating source, such as thermoelectric unit and electric boiler is established, and the heat flow of heating network and the power flow of power grid are calculated orderly, thus a fast calculation method for the combined electro-thermal system is formed. What’s more, a combined electro-thermal system with two-stage peak-shaving electric boiler is used as the example system. This paper validates the effectiveness and rapidity of this method through the example system, and analyzes the influence for the energy flow of combined electro-thermal system caused by the operating parameters such as the installation location of electric boiler, the outlet water temperature of heat source and the outlet flow rate, etc.

Model of Polysilicon Electro-thermal Micro Actuator and Research of Micro Scale Effect

A type of crank beam electro-thermal micro actuator was prescribed. Mechanical model of the actuator was established, and the static characteristic was analyzed.Comparing the theoretical analysis with experimental data, it is found that the thermodynamic character of material in micro actuator has a different variable regularity contrasted to that used in macro scale machines. It is the micro scale effect that results in the deviation between the simulating result and experimental results. The thermodynamic expression of polysilicon, which was fitted by means of the experimental data concerned, was used to modify the mechanical model. The modified model, in which the micro scale thermodynamic characteristic was considered, was more reasonable and could make the optimal design and control strategies analyzing the straight-line micro actuator more feasible.

ELECTRO-THERMAL EFFECTS AND DEFORMATION RESPONSE OF CARBON FIBER MAT CEMENT BEAMS

A carbon fiber mat is a sheet composed of intercrossing short carbon fibers,which has more stable and lower electrical resistivity compared with dispersed short carbon fiber mixed in cement.Thereby carbon fiber mat cement could exhibit obvious electro-thermal effect.When electrified,the temperature of composite structures made up of cement mortar and carbon fiber mat will rise rapidly.If the temperature field is not uniform,temperature difference will cause structures to deform,which can be used to adjust the deformation of structures.The temperature field and deformation response driven by the electro-thermal effects of a type of carbon fiber mat cement beams are studied.Firstly,the temperature and deformation responses are studied using theories of thermal conduction and elasticity.Secondly,experimental results are given to verify the theoretical solution.These two parts lay the foundation for temperature and deformation adjustment.

Microstructure and wear resistance of electro-thermal explosion sprayed stellite coating used for remanufacturing

Electro-thermal explosion directional spraying was used to prepare the stellite coating on substrate of the AISI 1045 steel. The morphologies of cross-section and worn scar, porosity, distribution of elements, micro- hardness and wear resistance of the coating were determined by means of SEM, EDAX, micro-hardness tester and sliding wear tester. Because of the compact construction, good bonding and high hardness, the coating is characterized by good wear resistance. The results show that the mainly failure mode of the stellite coating is micro- plowing.

STUDY ON THE THERAPEUTIC EFFECT AND MECHANISMS OF ELECTRO-THERMAL NEEDLING FOR TREATMENT OF VULVAL LEUKOPLASIA

In the present paper,444 patients with vulvar leukoplasia were treated by selectingacupoints in the local area and along the meridian plus Qugu（CV 2）and Huiyin（CV 1）and usingelectro-thermal needling.The total effective rate was up to 100.0％and the cure rate 87.3％.Theelectro-thermal effect directly acted on the affected area but strengthened the immunologic function ofthe whole body and raised the content of serum copper.

High-temperature corrosion-resistance performance of electro-thermal explosion spraying coating

As a new spraying technology used in the remanufacturing engineering, electro-thermal explosion spraying holds a lot of advantages. Electro-thermal explosion spraying coating aliquation phenomena are reduced and non-crystal, micro-crystal and millimicron-crystal and other microstructure are formed. The corrosion-resistance ability of electro-thermal explosion spraying coating in high temperature environment was surveyed respectively. SEM equipped with EDS was employed to analyze the microstructure of spraying coating before and after corrosion. The corrosion-resistance mechanism of the spraying coating was discussed.

ELECTRO-THERMAL MOXIBUSTION ON ACUPOINTS FOR TREATMENT OF 98 CASES OF SCIATICA

98 patients with sciatica are treated.by stimubting acupoints using a self-made electro-thermal moxibustion instrument.Results show that 82 cases arecured,8 improved and 5 effective,with the total effective rate of 96.9％.The temperature relesed from this instrument is adjustable.The electro-thermal moxibustion therapy is short in treatment duration and rapid in taking effect.Ithas no needling-induced pain and no side-effects,and is accepted preferably by patients.

Microstructure and Deposition Mechanism of C/SiCN Composites Prepared by Rapid Electro-thermal Pyrolysis CVD

Carbon fiber-reinforced silicon carbonitride ceramic matrix composites （C/SiCN） were prepared by rapid electro-thermal pyrolysis CVD using liquid polymer hexamethyldisilazane （HMDS, （CH3）3SiNHSi（CH3）3） as precursor. Microstructure morphology and production technique of C/SiCN composites were investigated. Scanning electron microscopy and transmission electron microscopy were respectively employed to characterize microstructures of the as-received C/SiCN composites samples. The high temperature pyrolysis of HMDS results in destruction of molecular chain, fracture of bonds, as well as liquid-gas-solid conversion from polymer to ceramic. Microstructures observation indicates that there is a high degree of coalescence between SiCN matrix and C fiber. The deposition model of liquid precursor electro-thermal pyrolysis CVD is different from that of gas precursor isothermal chemical vapor infiltration. Rapid liquid flow and slow gas diffusion are key factors for the difference of two methods. Preparation of rapid electro-thermal pyrolysis CVD consists of four steps including liquid polymer infiltration, polymer pyrolysis, rapid deposition of pyrolyzed substances and rapid densification, respectively.

THE FUZZY NUMERICAL VALUE SIMULATION OF NANOMETER ELECTRO-THERMAL IN HOT-WORKING

The fuzzy numerical value analysis method is adopted for the first time, which solves the problem of nanometer electro-thermal in filming process, The key technique is embodied by controlling the time distribution, temperature and press in the filming process. The concrete technique of filming is showed by establishing the fuzzy mumbership function of above three indexes, which improves the precision of the materials of nanometer electro-thermal in hot-working. At the same time, the principles of the fuzzy relationship mapping inversion （FRMI） is put forward, Therefore, the standardization and continuity can be met.

Design and Fabrication of 2-DOF Micromirror Array Based on Electro-Thermal Actuators

With surface- and bulk-micromachining, an 8 × 8 mirrors array is designed, fabricated and tested, which is based on electro-thermal actuators and can be addressed individually. The micromirror is square shaped, 4-corner-actuated. Its dimension is 200 μm × 200 μm. The substrate below it is caved away to ensure a tilt at an angle as large as possible. To protect the etch-sensitive features on the front side of the wafer undamaged during wet deep silicon etch on the backside, the wax protective coating process is used. Mirror actuated by powering an alternative pair of heaters will tilt in 2-DOF. If its 4 cantilevers/heaters are powered synchronously, it will move in a piston mode. The effective arrays are more than 80% out of the three finished wafers. When the ramp voltage frequency applied to a pair of neighboring cantilevers is 5 Hz at 10 V, the average tilting angle can be ± 8°.

Study on Approach of Static Security Assessment Accounting for Electro-thermal Coupling

A static security assessment approach considering electro-thermal coupling of transmission lines is proposed in this paper. Combined with the dynamic thermal rating technology and energy forecasting, the approach can track both the electrical variables and transmission lines’ temperature varying trajectory under anticipated contingencies. Accordingly, it identifies the serious contingencies by transmission lines’ temperature violation rather than its power flow, in this case the time margin of temperature rising under each serious contingency can be provided to operators as warning information and some unnecessary security control can also be avoided. Finally, numerical simulations are carried out to testify the validity of the proposed approach.

Synthesis of Ti₃SiC₂-Bicarbide Based Ceramic by Electro-Thermal Explosion

A polycrystalline dense Ti3SiC2 based ceramic material has been produced by several techniques. The effect of addition of TiC and SiC is also studied. The Ti3SiC2 material shows extraordinary electrical, thermal and mechanical properties. Furthermore, it shows a damage tolerance capability and oxidation resistance. In this work, we have synthesized Ti3SiC2 by electro-thermal explosion chemical reaction (ETE) with high current density (900 Amperes/a.u) followed by uniaxial pressure. The structural properties of the as-prepared materials are studied by x-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDX) techniques. The chemical cartography, imaging and electronic properties are investigated using Ultra-STEM and electron high energy loss resolution spectroscopy (EELS) techniques, respectively. The surface of Ti3SiC2 is characterized by means of X-ray photoelectron spectroscopy (XPS). High resolution C 1s, Si 2p, Ti 2p, Ti 3s core level spectra are explained in terms of crystallographic and electronic structure. Valence band spectrum is performed to confirm the validity of the theoretical calculations.

A study on temperature monitoring method for inverter IGBT based on memory recurrent neural network

The power module of the Insulated Gate Bipolar Transistor(IGBT)is the core component of the traction transmission system of high-speed trains.The module's junction temperature is a critical factor in determining device reliability.Existing temperature monitoring methods based on the electro-thermal coupling model have limitations,such as ignoring device interactions and high computational complexity.To address these issues,an analysis of the parameters influencing IGBT failure is conducted,and a temperature monitoring method based on the Macro-Micro Attention Long Short-Term Memory(MMALSTM)recursive neural network is proposed,which takes the forward voltage drop and collector current as features.Compared with the traditional electricalthermal coupling model method,it requires fewer monitoring parameters and eliminates the complex loss calculation and equivalent thermal resistance network establishment process.The simulation model of a highspeed train traction system has been established to explore the accuracy and efficiency of MMALSTM-based prediction methods for IGBT power module junction temperature.The simulation outcomes,which deviate only 3.2% from the theoretical calculation results of the electric-thermal coupling model,confirm the reliability of this approach for predicting the temperature of IGBT power modules.

基于金属化薄膜电容器状态在线监测的剩余寿命评估方法

模块化多电平变流器(MMC)是柔性直流输电系统的核心装备,其中子模块(SM)金属化薄膜电容器是MMC中的薄弱环节之一,故研究金属化薄膜电容器的状态监测和寿命评估对于提高MMC运行可靠性和制定系统维护计划具有重要意义。目前,现有金属化薄膜电容器的寿命评估方法未考虑电容器老化进程对电容值和等效串联电阻(ESR)的影响,难以准确实现不同服役状态下的电容器剩余寿命评估问题。因此,该文提出考虑当前电容值状态在线监测的金属化薄膜电容器的剩余寿命评估方法。首先,在考虑电容器老化速率与温度耦合关系的基础上建立了电容器ESR和电容值的老化模型。其次,在进行寿命计算时考虑到电容器的老化效应,根据提出的容值在线监测方法得到当前的电容值,推断出电容器已使用年限及电容器目前的ESR值,并代入建立的场路协同仿真电热耦合模型中计算得到电容器温度。最后,根据提出的剩余寿命模型对电容器当前剩余寿命进行预测。该文研究成果将为设备选型、系统设计和MMC系统子模块电容器的可靠性评估提供参考。

光栅MOEMS加速度计温度特性

由于硅微机械加速度计受温度影响,导致硅弹性模量和热膨胀系数发生变化,造成微光机电系统(MOEMS)加速度计标度因数漂移、测量稳定性下降等问题。首先,采用COMSOL软件对光栅MOEMS加速度计微机械结构部分进行了温度特性仿真,分析了硅弹性模量温度系数和热膨胀系数对光栅MOEMS加速度计微机械结构标度因数和零位的影响。其次,设计了温控精度达0.1℃的温度控制系统,并利用该系统对加速度计进行温度控制。最后,对光栅泰伯效应MOEMS加速度计温度特性展开测试,结果表明,加速度计的标度因数随温度升高而增大,零偏稳定性随温度的升高而降低,加速度计标度因数温度系数为0.30 V·g^(-1)·℃^(-1),零偏稳定性温度系数为-7.78μg/℃,其变化趋势与仿真结果一致。这为实现全温范围下高精度MOEMS加速度计奠定了基础。

基于TSV的三维集成系统电热耦合仿真设计

三维集成系统利用垂直堆叠技术,实现高性能与低功耗,其中硅通孔(TSV)技术是三维互连成功实施的关键。TSV技术缩短互连距离,提升信号传输效率和电磁兼容性,但同时引发电热耦合问题,威胁三维集成电路性能的进一步提升。综述了基于TSV的三维集成电路中电热耦合现象的仿真设计进展,详细介绍了电气和热仿真设计方法,并探究了电热耦合问题的潜在影响及缓解策略。为理解和应对三维集成系统中的电热耦合挑战提供了系统的分析,并对未来研究方向提供了指导。

计及电热耦合的动态最优潮流模型与算法

在电热协调概念基础上,结合输电元件随载流变化的电与热之间耦合的规律,以输电元件运行最大允许温度为其热载荷限值,并与传统方法相结合,构建新的动态最优潮流模型。该模型能够实现运行调度中对输电元件随载流变化的热惯性性质的利用,达到有效发挥输电元件输电能力的目的。在此基础上,采用求解微分方程的数值积分方法将该模型转化为代数表达形式的方程,基于内点法进行求解。针对问题的复杂性,进一步结合电热耦合的物理规律,以及内点法迭代过程中修正方程的特点,分别在模型和算法上提出约束数缩减技术和解耦的处理手段,从而降低求解复杂度,提高求解效率。最后通过算例分析验证了该模型和算法的有效性。

计及电热耦合的潮流数学模型与算法

电热协调(ETC)理论的提出对实时环境下输电元件载荷能力的有效利用具有重要意义,但由于电与热之间的紧密耦合,使电力系统的潮流计算变得复杂,文中针对该问题进行了深入研究。将输电线路热动态微分方程引入到现有的电力系统潮流模型之中,利用隐式梯形的差分方法将该微分方程代数化,使输电线路温度成为电力系统运行的一个新的状态量,从而提出了计及电热耦合的潮流计算数学模型,并在推导得到牛顿法求解该模型的修正方程基础上,进一步提出了适应电热耦合处理的简化计算方法,该模型和算法实现了电气量和其温度的统一处理,不仅反映潮流的电的信息,而且能够提供输电线路热惯性的动态过程,即温度变化信息,从而实现输电线路载荷能力由温度评判的目的。最后通过算例分析验证了该模型和算法的有效性,为进一步开展电力系统运行调度中的电热协调理论研究奠定了基础。

微电子机械系统中微尺度热物性研究进展

微电子机械系统 (MEMS)是结合微电子技术和微机械加工技术制造而成的微型机电一体化系统。MEMS中薄膜材料的厚度可达到微米、亚微米直至纳米量级。由于微尺度效应 ,薄膜材料的导热规律及其各种热物性参数 (如比热、热导率、热扩散率等 )与常规材料显著不同。设计MEMS时必须充分考虑微尺度效应 ,并使用合理的热物性参数值 ,才能保证微电子机械系统的热稳定性。本文从理论建模、实验测试和计算机模拟三个方面总结了近年来微尺度薄膜热物性的研究进展。

计及线路电阻随温度变化影响的电力系统最优潮流

传统最优潮流(OPF)虽然将电网的经济性、安全性和电能质量进行了很好的统一,但在其数学模型中,仅考虑了电网线路的电气模型,而忽略了实际情况下线路的电热耦合关系,因此采用传统OPF计算结果作为实际电网调度运行的参考有着较大的偏差。在电热协调理论的基础上,根据线路温度和线路电阻之间的电热联系,建立了考虑电热耦合关系的温度OPF模型。此外,为进一步提高算法的计算效率,对电、热模型进行解耦计算,然后基于内点法进行求解。最后,通过对IEEE 5节点系统,MATPOWER中的Case 30、Case 2736、Case 3012节点系统以及一个实际1856节点系统进行仿真测试,验证了该模型和算法的有效性与正确性。