PENTAX首部数码相机问世

日本PENTAX公司推出的全自动相机一向都颇为出色,但随着数码时代的来临,PENTAX现在亦要推出他们首部数码相机应市。新机的CCD像素虽然只有211万,但功能却相当全面,而且具有“大机”风范。PENTAX这次首度加入激烈的数码相机市场,又让消费者多了一个选择！     

CST可控驱动装置在煤矿胶带机上的应用

CST可控驱动装置可对胶带输送机进行优化控制 ,且有较强的组网能力。还可与胶带机控制系统配套使用 ,改善胶带机的技术性能 ,延长了胶带机的使用寿命。     

氟氯化碳:全球变暖的罪魁祸首?

龙年春节前后,全国各地乃至世界各地的酷冷空前,人们不禁感到困惑,不是说地球一直在变暖吗?此前,中国科学家崔伟宏、美国科学家S.弗雷德·辛格等人也强烈反对"全球变暖"的观点,认为自然是气候变化的主要驱动因素。2007年,联合国气候变化政府间专门委员会(IPCC)提出:"人类将会经历全球     

基于分层递增验证的可信管理软件构造方法

为了保证管理软件在整个生命周期内都具有可信性,在ICEMDA架构基础上融入可信性理论与方 法,提出了一种可信管理软件的模型驱动构造参考方法．通过分析国内外的研究现状,明确界定了管理软件 可信性概念,给出可信性判定问题描述．结果表明该方法以ICEMDA各层次上的构造体为中心,逐层进行可 信模型描述、可信指标度量、可信性判定与优化,借助ICEMDA的模型语义保持技术实现各层间可信性的保 持与传递,并以业务构件PSM模型的可信性判定为例简要介绍了该体系的具体实施机制     

飞思卡尔单片机在自动排爆车控制系统中的应用

系统以飞思卡尔公司MC9S12DG128单片机为主、以STC12C5410AD单片机为辅实现排爆车的控制核心,采用CCD图像识别技术,将检测到的数据传送给单片机,对数据进行相应处理,LCD液晶显示及语音播报。实验证明,系统方案合理,性能良好,能够实现竞赛题目的各项要求。     

利用恒流驱动技术的10～80V宽电压输入串联型开关电源

为拓宽开关电源产品的电压范围,提出了1种基于恒流驱动模式的能在10～80V宽电压范围工作的串联型开关稳压电源.该开关电源采用恒流方式驱动开关管,开关管在宽电压范围内始终能够得到理想的驱动电流.实验表明,该开关电源效率高、工作稳定、成本低,因此,可使用于工业用各种报警器产品和爆闪式信号灯中.     

Robust tracking control for micro machine tools with load uncertainties

The quality of the micro-mechanical machining outcome depends significantly on the tracking performance of the miniaturized linear motor drive precision stage. The tracking behavior of a direct drive design is prone to uncertainties such as model parameter variations and disturbances. Robust optimal tracking controller design for this kind of precision stages with mass and damping ratio uncertainties was researched. The mass and damping ratio uncertainties were modeled as the structured parametric uncertainty model. An identification method for obtaining the parametric uncertainties was developed by using unbiased least square technique. The instantaneous frequency bandwidth of the external disturbance signals was analyzed by using short time Fourier transform technique. A two loop tracking control strategy that combines the μ-synthesis and the disturbance observer (DOB) techniques was proposed. The μ-synthesis technique was used to design robust optimal controllers based on structured uncertainty models. By complementing the μ controller, the DOB was applied to further improving the disturbance rejection performance. To evaluate the positioning performance of the proposed control strategy, the comparative experiments were conducted on a prototype micro milling machine among four control schemes: the proposed two-loop tracking control, the single loop μ control, the PID control and the PID with DOB control. The disturbance rejection performances, the root mean square (RMS) tracking errors and the performance robustness of different control schemes were studied. The results reveal that the proposed control scheme has the best positioning performance. It reduces the maximal errors caused by disturbance forces such as friction force by 60% and the RMS errors by 63.4% compared with the PID control. Compared to PID with DOB control, it reduces the RMS errors by 29.6%.