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51.
Pin Yang Carolina A. Gomez Samantha Andrews Josef D. Sorenson Ken S. Chen 《Journal of the American Ceramic Society》2021,104(7):3247-3259
The electric discharge across a varistor granule filled air gap under a fast-rising voltage pulse was investigated for surge protection applications. The effects of temperature and pressure on the arc and the electrical conduction were analyzed by the characteristic changes in voltage waveforms triggered by a fast-rising high voltage pulse. In addition to the gap size, experimental results show that competing mechanisms among arc conduction, conduction through the varistor granule network, thermionic emission from Joule heating at granule-to-granule contact points, and the magnitude of the switching voltage dictate the maximum surge protection voltage for the filled air gap. Experimental evidence indicated that accumulated degradation was created at small contact points between varistor granules by repetitive assaults from longer duration, high voltage pulses. The uniqueness of using varistor over other dielectric granules in an air gap for surge protection is identified and discussed. 相似文献
52.
Flash pyrolysis, which combines conventional pyrolysis with flash sintering, was first conducted to produce polymer derived SiC-TiC nanocomposites. Pre-pyrolysis at 800℃ allows the conversion from titanium isopropoxide (TTIP) modified polysiloxane to an amorphous SiTiOC ceramic. The subsequent application of an electric field gives rise to the formation of turbostratic carbon and creates Joule heating to obtain a sample internal temperature of ~1400℃. The precipitation of β-SiC, TiC, as well as titanium oxides is realized upon carbothermal reduction of extensively phase separated SiO2 and TiO2 with carbon. Increasing TTIP content embodies the nanocomposites with prominent electrical percolation behaviors. The electrical transport of the synthesized ceramics follows an amorphous semiconductor mechanism. High thermal stability in air is guaranteed, thanks to the in-situ formed TiC nanocrystals and preferentially reduced amorphous carbon. Flash pyrolyzed nanocomposite with a Ti:Si molar ratio of 0.20 exhibits the highest electrical conductivity (0.696 S/cm) and minimum mass change (~2%) at 1000℃, serving as a competitive candidate for electro-discharge machining (EDM) applications or self-standing conducting devices that must withstand high temperature conditions. 相似文献
53.
The software that simulates the flow, temperature, concentration and the heat generation field in the Outkumpu flash smelting furnace, was developed by a numerical method of the particle-gas flow together with some chemical reaction models. Many typical operating conditions were chosen for simulation in order to obtain the effect of the distribution air, process air, central oxygen and the oil-burner position etc. The concepts about optimum op-eration, 3C(concentration of high temperature, high oxygen and laden concentrate particles), are concluded from these simulated results, which have been checked primarily by operational experiments. 相似文献
54.
利用闪光对焊的方法对所制备的SiCp/3003Al复合材料进行焊接,并对不同SiCp增强相体积分数的复合材料的接头强度和显微组织进行了分析。结果表明,接头的强度和悍缝区碳他硅颗粒富集带的宽度,均随着母材中碳化硅颗粒含量的增加而增加。 相似文献
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本文通过将三个较典型的Flash交互动画的程序案例作为《Flash交互动画》的实训教学案例,循序渐进由简到难,旨在让学生初步掌握通过AS 3.0的脚本语言编程实现用鼠标或键盘对动画播放的控制。 相似文献
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根据某新型装备特点,介绍了一种基于ARM Cortex-M3和SD卡的数据采集系统的硬件设计和软件设计;硬件部分包括信号调理电路、微控制器外围电路和SD卡接口电路3个方面;其中微控制器是基于ARM Cortex-M3微处理器设计的STM32F205VG,该设计采用微控制器自带的ADC模数转换器完成模数转换;软件部分包括系统软件和应用软件两部分,其中系统软件主要有主程序模块、初始化程序模块等;应用软件主要有信息采集、SD卡读写程序等;该系统设计采用ARM微处理器,充分利用了ARM的低功耗、高效率、体积小的优点,具有广泛的应用前景. 相似文献
59.
高位ADC的测试中,对输入信号的质量要求较高,一般的混合信号测试系统难以达到要求。论文提出了一种基于电流积分法的高位ADC典型静态参数测试方法,充分利用了聚丙烯电容在积分线性度方面的优势,搭建了合理的测试电路,并在ATE上完成了对某款14bit ADC的典型静态参数测试,实验表明,该方法设计简便,通用性强,而且测试效果良好,具有较强的实用性。 相似文献
60.
The increasing architecture complexity of data converters makes it necessary to use behavioral models to simulate their electrical performance and to determine their relevant data features. For this purpose, a specific data converter simulation environment has been developed which allows designers to perform time-domain behavioral simulations of pipelined analog to digital converters (ADCs). All the necessary blocks of this specific simulation environment have been implemented using the popular Matlab simulink environment. The purpose of this paper is to present the behavioral models of these blocks taking into account most of the pipelined ADC non-idealities, such as sampling jitter, noise, and operational amplifier parameters (white noise, finite DC gain, finite bandwidth, slew rate, and saturation voltages). Simulations, using a 10-bit pipelined ADC as a design example, show that in addition to the limits analysis and the electrical features extraction, designers can determine the specifications of the basic blocks in order to meet the given data converter requirements. 相似文献