电机过热的原因及处理办法

针对三相异步电动机过热的各种原因，从电机外部和内部两方面进行了详细分析，提出了相应的处理措施，以保证电机的正常运行。     

全面掌握Prescott主板最新供电技术

Prescott核心的P4处理器在推出时正值产品与技术新旧交替的过渡期,由于部分主板对其支持不够完备,特别是电源部分不符合新规范，加上用户对新规范不了解,致使装配和使用的问题接踵而至．如果您正被这些问题所困扰,这篇文章应该能帮助您弄清P4E对电源系统的要求,并让您了解最新的供电技术与规范。     

PPTC保护器件在无线电子产品中的应用

无线电子市场的蓬勃发展对电路保护提出了新要求，这是因为数字器件对过大的电流或者过高的电压变得更加敏感。由于锂电池的发展，以及电池充电技术的广泛应用，新的PPTC(聚合物正温度系数)保护器件应运而生。PPTC保护器件的性能好，体积小，对于要求元器件尺寸很小、重量很轻的产品是极为重要的。     

读友信箱

耳机的基本知识及选购 Q市面上耳机那么多,它们都有什么不同,又该如何选购呢?另外,好些耳机标称的低频下限都在20Hz以下,真有这么低?     

Photoluminescence and X-ray Diffraction of Distributed Bragg Reflector

Spectral and structural characteristics of distributed Bragg reflector (DBR) in vertical-cavity surface-emitting lasers were studied with photoluminescence and double- crystal X- ray diffraction measurement. The expected high quality epitaxial DBR structure was verified. In the X- ray double- crystal rocking curves of DBR the zeroth- order peak, the first and second order satellite peaks were measured. Splitting of diffraction peak appeared in the rocking curves was analyzed. The effects of introduced deep energy levels on the structural perfection and optical properties were discussed.     

Distributed Optical Fiber Sensor for Multi-point Temperature Measurement

The distributed optical fiber sensing technology is overviewed, which is based on Raman scattering light theory. Basic operation principle, structure, system characteristics and signal processing are discussed. This structure and method of the signal processing possess of certain spatial resolution, hence will ensure the practicability of system.