单片机控制的直流PWM调速装置的研究

与交流电动机相比，直流电动机结构复杂，成本高，运行维护困难。但是直流电动机具有良好的调速性能、较大的起动转矩和过载能力强等许多优点，因此在许多行业中仍有应用。文章介绍了一种利用单片机控制的PWM调速装置实现小功率赢流电动机调速的方法，具体详述了电路的设计思想、电路的组成以及工作原理。     

Ni层厚度对p-GaN/Ni/Au欧姆接触特性的影响

对p-GaN/Ni/Au欧姆接触特性与Ni金属层厚度之间的相关性进行了对比实验研究,利用XRD衍射结果与表面金相显微分析手段对Ni/Au双层金属电极在合金退火过程中的行为特性进行了细致探讨。分析结果表明:在Ni/Au电极结构中,由双层互扩散机制与NiO氧化反应机理决定,Ni层与Au层之间的厚度比率对p型GaN欧姆接触特性的优劣有重要影响,在Ni、Au层厚度相当时可获得最佳的p型欧姆接触。     

太阳电池掩膜窗口宽度与电极宽度比对光生电流性能的影响

提出了一个有效工艺设计参数——选择性扩散掩膜窗口宽度与电极宽度的比值T。研究结果表明,对不同的衬底浓度和掺杂浓度均存在一个最佳T值可以获得最大短路电流。选择性扩散浓度为1×1018~1×10-3cm-3时,其最佳T值为1;选择性扩散浓度为1×10-3cm-3时,最佳T值小于0.5。电极宽度的增加减小了光生电流,但对最佳T值影响较小。选择性掺杂浓度的增加会使得最佳T值减小。     

AEQ数字调音台维护及温度监测系统

我台广播设备数字化改造已经多年,改造核心设备AEQ数字调音台等由于使用年限增加故障率也逐年上升,对于广播安全播出是重大的隐患。针对AEQ调音台故障特点,探索出AEQ数字调音台的维修方法以及改进之处,并设计开发基于物联网技术对调音台等重要数字设备多点实时监测系统。     

Color-stable,ITO-free white organic light-emitting diodes with enhanced efficiency using solution-processed transparent electrodes and optical outcoupling layers

In this work, we demonstrate color-stable, ITO-free white organic light-emitting diodes (WOLEDs) with enhanced efficiencies by combining the high-conductivity conducting polymer PEDOT:PSS as transparent electrode and a nanoparticle-based scattering layer (NPSL) as the effective optical out-coupling layer. In addition to efficiency enhancement, the NPSL is also beneficial to the stabilization of electroluminescent spectra/colors over viewing angles. Both the PEDOT:PSS and the NPSL can be fabricated by simple, low-temperature solution processing. The integration of both solution-processable transparent electrodes and light extraction structures into OLEDs is particularly attractive for applications since they simultaneously provide manufacturing, cost and efficiency advantages.     

Thermal analysis and design of a 75-W hybrid-type DC–DC converter for space applications

Hybrid DC–DC converters for space applications should be designed for operation at full rated power within the military specification for temperature range of −55 to +125 °C. Hence, the thermal design is a crucial step in the design process of converter, ensuring that no component of the converter exceeds its rated maximum operating temperature. One of the objectives of this work is to guarantee that all electronic components operate below their maximum allowable temperature. For this purpose, a three dimensional model of a converter based on the finite element method was developed. Results based on numerical simulation were validated by experimental data from infrared camera. The total amount of dissipated power in every component was determined experimentally based on a prototype converter. In the case of a component with high power consumption, such as the field effect transistor, the increase in temperature was minimized by applying designed heat sink with a high-thermal-conductivity material.     

喷雾热解法制备功能材料研究进展

综合评述了喷雾热解技术在超导陶瓷、介质材料、固体燃料电池电极、催化剂、磁性材料、人工骨材料以及气体传感器薄膜等领域的研究进展,并指出了进一步发展的方向。     

铝电解电容器用国产电极箔发展概况

论述铝电解电容器用国产电极箔的现状和发展趋势。分析我国电极箔生产厂家在生产规模、工艺技术和产品质量等方面同国外同行间的差距。探讨国产电极箔的发展前景。     

一种基于图像DC系数的多比特水印

提出了一种新的多比特水印算法。该算法把基于图像自身的水印信息嵌入到图像的DC系数中,通过视觉模型控制DC系数的改变程度,在保证水印不可见性的同时,提高了水印的鲁棒性。为实现水印的盲检测,采用Gold码序列对水印信息进行了扩频。在检测阶段,充分利用Gold序列良好的相关性恢复出水印。应用所提出算法,把水印信息嵌入到一幅512×512的灰度图像中。实验表明,该算法对常规信号处理攻击和几何攻击具有很强的鲁棒性。