基于嵌入式技术的数字装备通用控制器

提出一种基于嵌入式技术的数字装备通用控制器，其主控模块选用嵌入式PC104主板，基于DSP和FPGA技术开发了可控制伺服电机或步进电机的运动控制单元和内置PLC模块．对数字装备通用控制器的硬件系统和软件系统的结构框架进行了总体阐述，并对系统主要功能模块的技术细节进行了分析．     

一种新型高频开关直流电源的硬件设计

电力系统中传统的相控整流型电源正在逐步被具有高精度、低纹波、高效率等特性的开关电源取代.作者介绍了一种专为电力系统研发的新型高频开关电源系统的结构组成原理,侧重介绍了系统的两个主要模块高频整流单元和监控单元的设计方法及在设计中的几个关键问题.系统采用80C196单片机硬件技术,实现了智能化控制,取得了良好的应用效果.     

时滞系统输出动态反馈H-infinity控制——LMI方法

考虑线性时滞系统输出动态反馈H∞控制问题,通过求解动态反馈控制器以实现给定的干扰抑制水平及指数稳定性.基于适当的状态变换,结合相应的Lyapunov-Krasovskii泛函设计方法,导出了以双线性矩阵不等式表述的检验控制器与泛函存在性的时滞相关性判据,较之于时滞无关性条件具有较小的保守性.通过引入待定参数集的方法,实现控制器与泛函的适当参数化,从而利用矩阵变换与运算技巧将控制器与泛函的存在性判据归结为关于参数集的线性矩阵不等式可解性条件,其数值解可以通过凸优化算法有效地求解.     

Sintering and Electronic Conducting Properties of Lao.7Ca0.3CrO3 Perovskite Synthesized by a Glycine-nitrate Process

La0.7 Ca0.3 CrO3 powder consisting of superfine and uniform particles （ 100-200 nm ） were synthesized using a glycine-nitrate process （ GNP ）. The sintering and electronic conducting properties of La0.7 Ca0.3 CrO3 were invetigated in the sintering temperature range of 1 200-1 450 ℃. The desired morphology of the powder significantly improved its sinterability. La0.7 Ca0.3 CrO3 ceramics sintered at 1 250-1 450 ℃ show high relative densities above 95 % . The ceramics sintered at 1 250-1 400 ℃ have very similar electronic conduct- ing properties, providing electronic conductivities around 55 Ω^-1 cm^-1 at a measuring temperature of 800 ℃ . Further increasing the sintering temperature to 1450 ℃ led to an apparent degradation of electronic conducting properties. This research demonstrates the advantage of the GNP in producing La0.7 Ca0.3 CrO3 with respect to the enhanced sintering properties and superior electronic conducting properties.     

武汉市电网用电量、电力负荷与气温的关系及预测模型研究

分析了用电量、电力负荷与气温的关系，对武汉市2002-2004年日用电量、电力负荷与日平均气温、最高气温、最低气温进行对比分析，计算出日用电量、最高负荷与气温之间一系列相关关系，其中夏季一般大于0．8，冬季一般低于-03；通过回归分析建立夏季用电量和用电负荷预测模型，利用气温预报，可实现对用电量和电力负荷的预测，对2004年实际结果进行回代检验，预测精度超过90％。     

基于Matlab的交直流混合输电系统的仿真研究

利用S imPowerSystem s工具箱建立了一个两交一直的交直流混合输电系统模型,并对交流故障、直流故障下的系统稳定性和动态响应进行了分析,并给出了仿真结果。通过与交流输电系统仿真结果进行了比较,可以看出,由于直流输电系统的调节速度快和短时过载能力强的特点,所以交直流输电系统具有更好的稳定性能和响应速度。     

技术本科院校公共关系策划的几点思考

如何树立学校社会组织良好的社会形象,拓展公共关系网络,争取社会资源在教学、实训、科研、就业等方面对学校的支持和发展相当关键,从公共关系角度针对外部公众的公众对象,谈谈对技术本科院校公共关系重要性、公共关系策划等对学校的推进作用。     

增益增强型CMOS运算放大器的自动优化算法

在增益增强型运算放大器优化中采用了自动设计方法,此方法在电路性能方程式和自适应遗传优化算法基础上对电路性能指标进行优化。该放大器在0.18μm CM O S工艺条件下中开环增益为92.1 dB,单位增益带宽积为1.78 GH z,相位裕度为55.1°和0.2%建立时间为1.27 ns,同时说明此优化设计方法的有效性。     

A spectral Integral method (SIM) for layered media

A spectral integral method is presented for electromagnetic scattering from dielectric and perfectly electric conducting (PEC) objects with a closed boundary embedded in a layered medium. Two-dimensional layered medium Green's functions are computed adaptively by using Gaussian quadratures. The singular terms in the Green's functions and the non-smooth terms in their derivatives are handled appropriately to achieve exponential convergence. Numerical results, compared with the ones obtained by using other methods, demonstrate the spectral accuracy and high efficiency of the proposed method. They also confirm that the spectral integral method (SIM) is applicable to concave objects.     

Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array

We report the use of a /spl sim/50-mW peak power 4.3-THz quantum cascade laser (QCL) as an illumination source for real-time imaging with a 320 /spl times/ 240 element room-temperature microbolometer focal-plane array detector. The QCL is modulated synchronously with the focal-plane array for differential imaging. Signal-to-noise ratios of /spl sim/340 are achieved at a 20-frame/s acquisition rate, and the optical noise equivalent power of the detector array at 4.3 THz is estimated to be /spl sim/320 pW//spl radic/Hz. Both reflection and transmission mode imaging are demonstrated.