基于DDS与数字电位器的正弦信号发生器设计

为了实现医用电磁导航系统波形发生装置的小型化、便捷化,介绍了一种采用DDS芯片AD9833与数字电位器AD5252芯片来产生幅值、频率、相位均可调的正弦信号发生装置。系统利用C8051F320单片机通过SPI通信控制AD9833来调节正弦波的频率、相位,通过IIC通信控制数字电位器AD5252配合运算放大器实现正弦波幅值的调节。同时,开发了一个基于VB语言的上位机界面,能实现直观、便捷的控制。实验结果表明,本信号发生装置工作可靠、易于控制、输出信号精度高。     

隧道磁电阻(TMR)磁传感器的特性与应用

基于TMR效应的磁传感器具有灵敏度高、体积小、功耗低等诸多优点,可广泛应用于信息技术、电子电力、能源工业、汽车电子、工业自动控制及生物医学等领域。采用国内某公司开发的TMR传感器芯片,我们对TMR芯片在电子罗盘、电流传感器、角度传感器、双极锁存开关传感器、验钞机磁头等方面的应用进行了研究。本文主要介绍这些传感器的工作原理及其性能特征,并展望了TMR传感器的应用前景。     

稳步增长,挑战与机遇并存 中国吸尘器市场2011年回顾与2012年展望

随着我国国民经济快速发展,国民的生活水平和生活质量日益提高,特别体现在对于小家电的需求增长。2011年,吸尘器市场零售量保持稳定增长,各大厂商在产品设计和研发上向环保智能化发展,推动整体高价位段市场份额提升。另一方面,以美的、莱克等为代表的国内品牌经过多年发展,依靠其庞大的销售网络,推动了整体吸尘器市场的增长。     

箱式变压器噪声治理的研究与应用

通过对某35 kV变电站箱武变压器噪声传播的分析与研究,在保证变压器正常通风的条件下,设计了整体式消声器,制定了空气声和固体声的具体治理措施并加以实施,有效降低了箱式变压器的噪声辐射,减少了对附近居民的声环境影响.可为电网运行部门应对环保投诉和变压器噪声治理提供成功案例借鉴.     

积极创新课堂教学方法 不断提升研究生教学质量

研究生课堂教学是研究生培养的基础环节,积极创新课堂教学方法,对于提高研究生教学质量具有重要意义。论述了研究生课堂教学方法的重要地位和作用,分析了当前课堂教学方法存在的主要问题,明确了研究生课堂教学方法创新的基本原则,探索了几种研究生课堂教学的创新方法。     

油流放电和绝缘降低缺陷的原因分析及处理对策

分析了220kV变电站主变压器内部油流放电和绝缘降低故障的原因,提出了处理办法和预防措施.     

35 kV线路悬挂式避雷器的应用

胜利油田部分地区35kV输电线路每年雷雨季节经常发生因雷击造成线路跳闸事故,普通的防雷设施已经不能适应恶劣环境的要求,因此,提出了在雷击多发地区的35kV输电线路安装带脱离器的悬挂式避雷器。     

Effect of Center High Explosive in Dispersion of Fuel

The dispersion of the fuel due to the center high explosive, including several different physical stages,is analyzed by means of experimental results observed with a high speed motion analysis system, and the effect of center high explosive charge is suggested. The process of the fuel dispersion process can be divided into three main stages, acceleration, deceleration and turbulence. Within a certain scope, the radius of the final fuel cloud dispersed is independent of the center explosive charge mass in an FAE (fuel air explosive) device, while only dependent both on the duration of acceleration stage and on that of the deceleration. In these two stages, the dispersion of the fuel dust mainly occurs along the radial direction. There is a close relation between the fuel dispersion process and the center explosive charge mass. To describe the motion of fuel for different stages of dispersion, different mechanical models should be applied.     

电镀漂洗水无排放自动生产线的研究

介绍一种新型的环保型电镀自动线,采用微量雾化水反喷射清洗技术和强化清洗效果等方法,在电镀自动线上可使多种电镀漂洗水无排放,实现了清洁生产.     

纳米γ-Fe2O3/SiO2复合氧化物的制备及气敏性质

Nanostructured γ-Fe2O3/SiO2 complex oxide was prepared by sol-gel method with tetraethoxysilane and iron nitrate as precursors. The particle size distribution, thermal and phase stabilities and gas sensing properties were systematically characterized by TEM, granularity distribution, TG-DTA, XRD and gas sensitivity measurements. The particle size is about 10 nm and size distribution is very narrow. The sensitivity of the sensing element to CO, H2, C2H4, C6H6 and the effects of zalcination temperature on the sensitivity and conductance of gases were examined. The combination of excellent thermal stability and tunable gas sensing properties through careful control of the preparation and judicious selection of material compositions gives rise to novel nanocomposites, which is attractive for the sensitive and selective detection of reducing gases and some hydrocarbon gases.