电热型复合绝缘子防覆冰性能分析

复合绝缘子覆冰会对电网的安全运行造成威胁,将电热型涂料涂覆于复合绝缘子表面能有效防止覆冰。基于传热学理论,建立了复合绝缘子雨凇覆冰时的传热平衡模型,提出了临界防冰功率的计算方法并总结了其影响因素。复合绝缘子临界防冰功率介于0~136.8 W之间,临界防冰电流介于0~4.15 mA之间,环境温度与风速对临界防冰功率与电流有显著影响,而水滴中值体积直径影响较小。根据电路理论,给出了复合绝缘子电热功率的计算方法,推算出防冰用电热型涂层体积电阻率介于0.11 M?·cm与2.36 M?·cm之间。对涂覆石墨含量为20%、23%、25%电热型硅橡胶涂料的复合绝缘子进行了覆冰试验,试验表明以上绝缘子均有一定的防冰效果,防冰性能随涂层电阻的减小而提升。

基于超顺排碳纳米管/高分子复合材料的手臂状电热型致动器（英文）

与超顺排碳纳米管薄膜相互浸润的高分子具有均匀的导电性、良好的生物兼容性、合适的力学性能,它在电热型致动器研究领域具有广阔的应用前景。在本文中,首先利用这种具有双层结构的复合材料制作了一个简单的U型小器件来展示电热致动器的工作原理,在电热的作用下该小器件能够产生730°的卷曲。其次,本文介绍了一种具有旋转结构手臂状的致动器(人工手臂)。在低电场(小于41 V or 500 V/m)的作用下,该人工手臂能够产生大的形变(大于700°旋转,49.2%的长度收缩和26.4%的直径收缩)。所制作的人工手臂和U型小器件能够受电压(或电功率)的精确控制。该人工手臂能够握起4 g(自重的26倍)的重物,展示了一种新的抓取物体的方式,在仿生领域具有良好的应用前景。

电热型X荧光分析熔样机的研制及性能测试

介绍了自行研制的电热型X荧光分析熔样机的结构、特点及性能指标。熔样机本体采用新型高性能保温隔热材料、马弗炉式结构,炉内安装了拥有自主知识产权的、可旋转的高温陶瓷载样盘,可放置4个自动成形用的坩埚;炉体可进行程控摆动,通过载样盘的旋转和炉体的摆动实现样品的均匀化。熔样温度、熔样时间、转摆频率和总次数等参数由配备有大型液晶显示屏的控制面板设置,简便、易学。利用载样盘的手动旋转功能,可以将任意样品旋转至炉口位置后取出,减少炉温对操作者的热辐射量。性能测试结果表明,熔样机的最大温升为1250℃,温控精度为±1℃,可在15min内制备4个样品,制样精度优于0.3%(RSD,n=11)。

涂覆电热型涂料的复合绝缘子直流电场仿真与电气特性试验研究

复合绝缘子覆冰会对电网的安全运行造成威胁。将电热型涂料涂覆于复合绝缘子表面能有效防止覆冰,但会对安全性能造成影响。为研究电热型涂层对复合绝缘子电场的影响,基于有限元法对涂覆电热型涂料的复合绝缘子进行直流电场仿真计算,得出"开关"数量越多,对复合绝缘子电位分布的改变程度越弱,沿面电场畸变点越多,并以沿面电场低于电晕起始场强作为标准,选择出最优的涂层布置方式。通过对电热型复合绝缘子进行直流电气特性试验,得出涂层电阻会使污闪电压下降,污层盐密对污闪电压和冰闪电压的影响规律取决于涂层电阻,并以最大耐受电压高于系统目标耐受电压作为标准,筛选出满足安全性能的电热型复合绝缘子。

基于GA-BP神经网络控制的电热型流量调节阀

针对供暖系统在实际运用中为一个滞后过程,难以保证其供暖介质流量控制精度的问题,利用感温石蜡的热胀冷缩效应作为电热型流量调节阀执行结构的动力源,获取石蜡温度与流量之间的关系,提出基于遗传算法的BP神经网络(GA-BP)方法。首先获取供暖系统温度,通过电热器加热石蜡得到其温度变化量与流量,然后应用GA-BP神经网络方法,对流量进行预测。通过与3次B样条函数递推最小二乘法、BP神经网络法对流量的预测结果对比试验验证,预测值和真实值的最大绝对误差分别为0.19、0.35、0.87,且均能满足实际应用的控制周期。结果表明,GA-BP神经网络对流量的控制更为精确。

电热型皮托管焊接工艺特殊过程的识别和确认

电热型皮托管部分焊接工艺形成的特性和质量特征不能或无法经济地验证,属于特殊过程。论述了电热型皮托管焊接工艺中特殊过程识别和确认的原则。利用FMEA方法对特殊过程进行识别,明确了特殊过程中需要确认的影响因素,并且提出了确认方法和再确认的条件。

基于电热型扫描微镜的微型双光子显微镜探头设计

双光子荧光显微镜的微型化对在体脑部神经活动研究和体内组织病理状态检测具有非常重要意义。本文设计了一种基于电热型扫描微镜的微型化双光子荧光显微镜探头,其微镜设计采用反向串联双S型双层材料结构,通过对微镜四个侧面执行器分别施加周期信号,实现了±3.5°的扫描范围;其光学设计是通过单模光纤导入800 nm飞秒激光,激光经微镜扫描,由光学系统聚焦作用于生物样品,激发样品产生荧光,荧光信号通过采集光路汇集并耦合到多模光纤输出,最后通过显微镜的图像采集系统成像。探头尺寸为26 mm(L)×12 mm(W)×8 mm(H),重量为5.6 g。利用该显微镜探头,对含有不同尺寸凹槽的微结构进行了成像测试,其结果表明,其扫描成像的范围可以实现150μm×150μm,横向分辨率可达到5μm;利用该探头对荧光染色小鼠肾脏冷冻切片进行的成像测试,成功得到了双光子二维荧光图像。基于本装置以及进一步的改进,将有助于构建便携式双光子荧光显微镜,置于活体动物头部,在体进行脑部神经活动研究。

电热型空调器结构设计分析

冷热型空调器主要分为电热型空调器和热泵型空调器。由于热泵型空调器受气候影响干预较大，电热型空调器得到了广泛的使用。本文对电热型空调器的结构设计进行了深入的分析和讨论。首先，给出了电热型空调器的系统结构图，详细介绍了构成电热型空调器系统的各个组成部分。然后根据系统结构图讨论分析了电热型空调器的制冷和制热工作过程。最后，根据电热型空调器的特点给出了其安装过程的一些建议。

防覆冰涂覆材料的应用分析与研究

对电热型、光热型、憎水性3种防覆冰涂覆材料的防冰原理进行分析,指出在这3种防覆冰涂覆材料中,电热型徐覆材料因其在运行中带来的负面影响较大,因此没有必要深入研究;光热型涂覆材料因受连续阴雨天气的限制而使其防冰效果大打折扣:憎水型防覆冰涂覆材料的技术关键在于对较高接触角聚合物的研究。文章对硅基与氟基聚合物的性能进行了对比,结合已经在电网中使用过的硅类聚合物的生产实践,指出了氟基类聚合物是防覆冰涂覆材料的研究方向,具有良好的应用前景。

Electrotransformation of Thermotoga maritima MS8

[Objective] The aim was to study on the electrotransformation of Thermotoga maritima MS8.[Method] Square waves,exponential waves and high voltage shock were used for the electrotransformation of T.maritima MS8,and the obtained transformants were detected by PCR.[Result] A single square electric pulse could be applied to cell sample in 0.2 cm ET cuvettes by using a Bio-Rad Gene Pulser set at 150 V,25 ms at room temperature,but the transformation efficiency was very low.[Conclusion] This research may improve the transformation efficiency of T.maritima MS8.

Heat transfer model for microwave hot in-place recycling of asphalt pavements

In order to solve for temperature fields in microwave heating for recycling asphalt mixtures, a two-dimensional heat transfer model for the asphalt mixtures within the heating range is built based on the theory of unsteady heat conduction. Four onedimensional heat transfer models are established for the asphalt mixtures outside the heating range, which are simplified into four half-infinite solids. The intensity of the radiation electric field is calculated through experiment by using heating water loads. It is suggested that the mathematical model of boundary conditions can be established in two ways, which are theoretical deduction and experimental reverse. The actual temperature field is achieved by fitting temperatures of different positions collected in the heating experiment. The simulant temperature field, which is solved with the Matlab PDE toolbox, is in good agreement with the actual temperature field. The results indicate that the proposed models have high precision and can be directly used to calculate the temperature distribution of asphalt pavements.

Structure and Properties of Hydrotalcite Using Electrostatic Potential Energy Model

The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and the anionic stability of the hydrotalcites was investigated. The charge density of the layer and the distance between the adjacent anions varied with the molar ratio of Al^3＋/（Mg^2＋ ＋ Al^3＋）. Anionic potential energy depended on the charge and size of the anions. Calculation results remained consistent with thermal stability and the ion exchange ability reported. This model is able to predict anionic stability of the hydrotalcites.

Fabrication and thermal performance of grooved-sintered wick heat pipe

Some novel grooved-sintered composite wick heat pipes(GSHP) were developed for the electronic device cooling.The grooved-sintered wicks of GSHP were fabricated by the processes of oil-filled high-speed spin forming and solid state sintering.The wick could be divided into two parts for liquid capillary pumping flow:groove sintered zone and uniform sintered zone.Both of the thermal resistance network model and the maximum heat transfer capability model of GSHP were built.Compared with the theoretical values,the heat transfer limit and thermal resistance of GSHP were measured from three aspects:copper powder size,wick thickness and number of micro grooves.The results show that the wick thickness has the greatest effect on the thermal resistance of GSHP while the copper powder size has the most important influence on the heat transfer limit.Given certain copper powder size and wick thickness,the thermal resistance of GSHP can be the lowest when micro-groove number is about 55.

A Two-Layer Model for Superposed Electrified Maxwell Fluids in Presence of Heat Transfer

Based on a modified-Darcy-Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instability under an electric field, is an electrostatic force exerted on the free charges accumulated at the dividing interface. Normal mode analysis is considered to study the linear stability of the disturbances layers. The solutions of the linearized equations of motion with the boundary conditions lead to an implicit dispersion relation between the growth rate and wave number. These equations are parameterized by Weber number, Reynolds number, Marangoni number, dimensionless conductivities, and dimensionless electric potentials. The case of long waves interfaciaJ stability has been studied. The stability criteria are performed theoreticaily in which stability diagrams are obtained. In the limiting cases, some previously published results can be considered as particular cases of our results. It is found that the Reynolds number plays a destabilizing role in the stability criteria, while the damping influence is observed for the increasing of Marangoni number and Maxwell relaxation time.

Geometric Design of Anode-Supported Micro-Tubular Solid Oxide Fuel Cells by Multiphysics Simulations

High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.

The Upper Mixed Layer during Coastal Upwelling Events on the Northern Portugal Shelf

The upper mixed layer (UML) depth obtained from temperature is very close to that from density:the maximum is about 15m. This indicates that temperature is a good indicator of mixed layer during measurements. When the surface heat flux is balanced by a cross-shore heat flux, the surface mixed layer depth obtained from the WM model (Weatherly and Martin, 1978),hPRT, is roughly the same as observed. The mixed layer depth calculated from the PWP model (Price, Weller and Pinkel, 1986) is close to the depth obtained from thermistor chain temperature data. The results show that both the WM model and PWP model can provide a good estimate of stratification in the study area during the cruise. The value of log( h/u3) is about 9.5 in the study area, which shows that the study area is strongly stratified in summer. Observations on the northern Portugal shelf reveal high variability in stability, giving rise to semi-diurnal, semi-monthly and diurnal oscillations, and long term variations. The fortnightly oscillations are highlighted by post-springs and post-neaps. The stirring of spring tide is reinforced by strong wind mixing which brings about complete vertical homogeneity everywhere. The semi-diurnal periodic stratification is very pronounced because the major axis of the tidal ellipse is orientated acrossshore, even though the tidal current is weak in this area, the maximum stratification is observed around the middle of ebb, and, the water at this time is much warmer. The diurnal oscillation results from the upper ocean response to heating and wind mixing when solar heating warms and stabilizes the upper ocean. There is a clear relationship between upper mixed layer depth and wind-stress magnitude at subtidal frequencies. Stronger winds result in a deeper surface mixed layer. Typically, the surface mixed layer depth lags the wind stress by 6 -12 h.