高效节能LED驱动电路设计

采用NPN三极管8050构建的驱动电路和单片机STC89C52实现了高亮度白光LED控制系统.系统分为主控制单元和驱动单元两个部分,采用主从式传输控制方式,驱动单元控制电路实时采集所需的数据,并及时上传至主控制器,而主控制器则根据上传的实时数据,对驱动单元下达设定数据以及控制命令;通过单片机发送PWM脉冲控制高亮度白光LED开关以及自动调光和故障自诊断报警.该系统具有传输距离远、响应速度快、操作简便、性价比高、工作稳定、可靠性高等优点.     

《会合》，值得珍视的序曲

《会合》是动荡时代与诗人纯正心灵的结晶，可以说，时代产生了《会合》，《会合》产生了一位杰出的诗人。《会合》浸透着艾青美学原则的精粹，它以清纯而又明确的主题，写实且具现代的艺术手法，歌唱热血青年的可贵精神。《会合》，表明艾青诗歌创作的起点，远比同样从法国艺术的氛围中走出的“象征派诗人”李金发、“雨巷诗人”戴望舒要高，他是浩瀚无垠的大海。     

Investigation of blood pulse PPG signal regulation on toe effect of body posture and lower limb height

Objective: To study the regulation of blood pulse volume via photoplethysmography (PPG) signal detected from toe, while the lower limb is passively raised in different height positions. Methods: Use a modified non-invasive PPG technique to detect the blood pulse signal on toe with infrared (IR) photo sensor. A protocol consisting of two postures, i.e., supine and 45° reclining, was designed to conduct laboratory trial in this study. During the period of performing the protocol of these postures, the lower limb was passively raised from the heights of 10 cm to 60 cm randomly and individually with sponge blocks underneath the foot. Results: In the supine posture, the higher the foot was passively raised, the more the blood PPG signal decreased. In the 45° reclining posture, the blood PPG signal increased at the beginning and then decreased in the foot height position from 10 cm to 60 cm. In both postures the normalized AC signal changes significantly while the normalized DC signal changes little. Conclusion: The toe PPG signals can obviously indicate the regulated blood volume change with the designated postural procedures due to the heart level position.     

高职高专“建筑工程测量”课程教学改革初探

针对目前高职高专"建筑工程测量"课程体系和课程内容滞后于行业发展和科技进步的问题,为了提高教学质量,文章从课程体系构建、教学内容设置、教学方法改革以及职业道德及素质培养四个方面进行探讨,提出课程教学改革思路。     

超高斯脉冲在光子晶体光纤中的传输特性

基于非线性薛定谔方程和应用变分法导出的具有不同陡峭程度的超高斯光脉冲在光子晶体光纤中传输时的演化方程组,研究了超高斯脉冲在光子晶体光纤中的传输特性.导出了超高斯脉冲参数随传输距离的变化关系式,并对结果进行了分析讨论.结果表明:脉冲振幅和脉冲宽度满足绝热关系,频率保持不变,脉冲前后沿锐度对超高斯脉冲中心位置没有影响和脉冲在传输过程中会产生啁啾.     

分光光度计有效测量范围的生化实验验证

为了在生物化学实验讲解中更直观地说明使用分光光度计时的有效测量范围,分别测定了不同浓度的苯丙氨酸和pSK质粒的光吸收值,与相应的标准浓度对照,计算出不同光吸收值的偏差,得到光吸收值与测量偏差的曲线。实验结果表明,当光吸收值小于0.1和大于1.0时,测量偏差超过10%,而当光吸收值在0.1~1.0之间时,测量偏差小于10%(当光吸收值在0.3~0.7之间时,测量偏差小于4%),测量值有效可信。本实验以氨基酸和核酸两种物质为例,验证了分光光度计的有效测量范围为0.1~1.0。     

电容式强脉冲电源的改进

改进后的电容式强脉冲电源性能稳定,操作方便,用于磁铁充磁和演示通电导线、线圈的磁场,能取得理想的实验效果,尤其能适用于中学生开展科技活动的需要.     

GS-1光栅式弹性模量实验仪的研制

利用光栅尺精细刻度和位移检测探头的关系，设计方波脉冲发生电路来记录弹性模量，并用单片机进行数据采集和处理，同时在数码管上进行位移量的显示．本仪器的研制，使得弹性模量实验测量精度大大提高，操作更加快捷．     

光脉冲传输方程中不同傅立叶变换形式的讨论和仿真分析

对光脉冲传输过程中的准单色光波正负频表示、傅立叶变换的正负频形式进行分析,由此得出了两种不同表示形式的光脉冲传输方程．指出了在采用分步傅立叶法进行数值仿真时必须采用正确形式,并结合实例验证了讨论结果．     

Effects of parameters in femtosecond laser micromachining on ablation of silicon

A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope (AFM),scanning electron microscope (SEM),focused ion beam (FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.