基于STM32单片机的照度稳定可调LED台灯设计与实现

基于STM32单片机设计制作照度稳定,可根据环境变化自动调节的LED台灯,系统由LED灯板、光照检测电路、电压控制电路构成。数字可调电阻模块、降压模块构成高效、低损耗的稳压电源电路,单片机编程控制LED灯板电源的输入,达到调节LED灯板亮度的目的,照度传感器检测LED灯板下方任意位置的亮度,显示屏实时显示系统状态。     

基于STM32单片机的照度稳定可调LED台灯设计与实现

基于STM32单片机设计制作照度稳定,可根据环境变化自动调节的LED台灯,系统由LED灯板、光照检测电路、电压控制电路构成。数字可调电阻模块、降压模块构成高效、低损耗的稳压电源电路,单片机编程控制LED灯板电源的输入,达到调节LED灯板亮度的目的,照度传感器检测LED灯板下方任意位置的亮度,显示屏实时显示系统状态。     

基于STM32的舞台灯光控制系统设计

根据舞台灯光的应用场合和应用模式,设计了一种基于STM32的舞台灯光控制系统。阐述了以STM32F103系列芯片为核心处理器的整体硬件平台架构,然后以模块化的角度详细介绍了如何完成DMX512数据通信、电机驱动和RGBW四色灯芯驱动,最后软件上采用PWM调光技术实现调光曲线输出、LED彩虹效果和频闪设计。该系统具有混色纯正和调光输出曲线顺滑、线性等特点,能够稳定运行且成功应用于产品中。     

小型户外专业设备的多功能移动电源设计

基于当前户外专业设备缺乏移动电源的现状,设计了一款小型户外专业设备便携式供电移动电源。该移动电源具有多种功能,可实现3.3 V～12 V的供电。设计过程中,优选移动电源的外形构造及多种功能,创新研发了两种供电方式,既可基于太阳能电池板实现移动电源电压输入,采用共射放大器控制整流二极管的导通与截止,经变压器降压为5 V直流电;也可通过变压器与整流电桥直接将220 V市电转化为5 V直流电,存储于蓄电池。进而,深入研究了移动电源的调压功能,采用基本放大电路和AMS1117三端线性降压电路实现固定调压,并利用PWM原理实现手动控制输出电压,在单片机的辅助控制下,实现在3.3 V～12 V间自由调压输出。最后,设计移动电源安全保护电路,通过仿真模拟可调电压与整流电路实验,得到的实验结果与预期目标符合率达99.95%,表明了所设计的可移动电源具有可行性和合理性。     

家庭交直流多功能语音报警器系统分析

本系统主要实现防盗语音报警、火灾语音报警和煤气、天然气等气体泄漏报警;防盗语音报警器采用无线遥控控制。本设计由STC90C58AD单片机、MQ2传感器、热释电红外传感器、交直流电源电路、语音报警电路、显示电路、无线遥控电路、LED电路等组成。电路的电源部分有两块,一块是交流电通过开关电源变成直流电供电,另一块是电池供电。语音报警声电路由特制OTP语音芯片发出救火声、防盗声、及语音提示声。电路开始报警器时LED灯打开,可以提供照明。通过声音报警吓跑小偷或提醒用户气体泄漏或着火等实用功能。     

同步降压电路的EMI改进

同步降压电路广泛应用于DC-DC电源电路中,本文针对该拓扑进行了电磁干扰分析,提出了可以改进EMI的各种措施及PCB设计需要注意的事项,并最终进行了试验对比验证。对同类电路的EMC设计有一定参考价值。     

工程机械中电源处理电路的优化设计

市政工程中所用到的工程机械,如挖掘机、吊车、叉车、铺路机等,因输出功率大,需采用柴油机作为动力源;然而,柴油机所提供的电源非常不稳定,影响了监控其运行状态的电子设备。介绍了一般的电源处理电路中采取的三端稳压芯片降压、稳压芯片和滤波电容组合以及前置熔丝等3种方法。着重就电源处理电路的优化设计、电路构成及功能分析进行了论述。该项技术运用于叉车的监控系统,能保证其正常运行。该叉车组合仪表用电源电路已申请专利并获批准。     

基于分时复用的可见光通讯方法研究

可见光信息传输是利用分时复用技术实现多通道数据同时传输,将要传递的信息以极高的频率闪烁形式(1为亮0为灭)进行传输。通过光敏设备检测这种人眼不可见的高频后,将其还原为要传输的数据信息。本文设计了一套基于可贝光的信息传输系统。该系统由两个单片机分别控制两个独立的部分:LED控制电路、光测量电路。其中LED控制电路包括单片机stm32主控模块、白光LED、LED驱动电路;光测量电路包括硅光电池板、MP3模块、LCD液晶显示模块、按键。该系统由LED控制电路控制光源分时高频闪烁,再由光测量电路接收上述高频闪烁光,根据前导码来区分对应的LED灯,然后再进行有效数据的光电解码。     

基于PT4115的LED照明灯系统设计

本文设计了一种基于PT4115的控制大功率LED照明灯控制系统。系统LED采用由PT4115构成的恒流源驱动电路进行驱动,采用STM32对PT4115进行控制能够实现亮度从0~100%可调,同时通过DS128B20温度传感器实时检测LED散热板的温度,调整输出可防止LED温度过高,从而提高LED的使用寿命。     

黄疸光疗仪LED光源PWM调光电路仿真研究

为进一步提高新生儿黄疸光疗仪LED光源降解胆红素的效率,本文设计了一种能够实现多通道控制的黄疸光疗仪LED驱动电路,对数目不同的五种不同峰值波长单色LED进行独立调光。利用NE555定时器输出可调脉冲波以及MAX16823芯片具有三个亮度调节输入可在宽范围内实现独立脉宽调制调光(PWM调光)的特性组成多通道脉宽调制LED驱动电路,并分析调光方式的优缺点。通过Multisim10对该电路设计方案进行仿真验证。仿真结果表明:该LED驱动电路方案可对黄疸光疗仪LED光源实现多通道独立PWM调光。     

基于UC3844控制的双管正激式变换器在电动自行车充电器中的应用

设计一种恒压充电器,本质是由UC3844控制的双管正激式开关电源,本文给出了主电路和控制电路的拓扑结构,并对其工作原理进行了详细分析,通过实验对其效果进行了验证,达到设计要求。     

关于武汉市都市核的初步战略研究

武汉作为一个跨两江、分三片同时发展的区域中心型特大城市,从其发展历史和现实条件看,均有发展CBD的必要.武汉的CBD应具有组合型特征.武汉需要一个能对三镇进行有效整合的中央都市核心空间,这个核心空间由江北分核、江南分核、南岸嘴及其延伸段三部分组成,以"两桥两隧"的过江交通、四条轨道交通线为主体的交通输配环围合.     

The Way It Was

Reflecting on 50 years as a planning educator, Teitz describes planning education in one institution, the University of California, Berkeley, especially in the 1960s and 1970s, carrying through to the reorganization of the Association of Collegiate Schools of Planning (ACSP) in the 1980s. How theory and practice engaged him during that time and later is discussed through the lens of his involvement in research, teaching, and planning consultancy and the formative phases of two research institutes.     

UC伯克莱土木与环境工程系本科教学计划浅析

本简要介绍并分析了美国伯克莱加州大学土木与环境工程系1996－1997学年的本科教学计划,从中可以略窥美国土木工程高等教育的某些特点。     

UC Berkeley能源与环境课程教学观察与感悟

美国UC Berkeley能源与环境课程从教学内容和教学目的看,类似于中国建筑环境与设备专业的建筑环境学课程。基于课程的网站信息和笔者30余学时的课程旁听记录,介绍该课程的定位、课程结构、课堂教学状况以及笔者的感悟和体会,旨在让国内同行对国际一流大学相关课程的教学内容、方法和手段有更多的了解和认识,为中国同类课程的教学改革提供参考。     

水泥改性聚乙烯醇固化轻质土的强度特性

为改善水泥固化轻质土存在的不足,采用水泥-改性聚乙烯醇(SH)对轻质土进行固化.分析探讨了水泥-SH固化轻质土的受压破坏方式、应力-应变曲线类型以及龄期、养护环境、SH掺量、土质成分对水泥-SH固化轻质土无侧限抗压强度的影响.结果表明:水泥-SH固化轻质土受压破坏没有出现明显的破裂面,且破坏应变较大,有较高的残余强度;室温养护下水泥-SH固化轻质土的无侧限抗压强度显著高于恒温恒湿养护;SH固化剂显著提高水泥固化轻质土无侧限抗压强度的最低掺量为4.5%(质量比);SH固化剂可以减小土质成分对水泥固化轻质土无侧限抗压强度的影响.     

Bridging the gap between laboratory and field moduli of asphalt layer for pavement design and assessment: A comprehensive loading frequency-based approach

Asphalt pavement is a key component of highway infrastructures in China and worldwide. In asphalt pavement design and condition assessment, the modulus of the asphalt mixture layer is a crucial parameter. However, this parameter varies between the laboratory and field loading modes (i.e., loading frequency, compressive or tensile loading pattern), due to the viscoelastic property and composite structure of the asphalt mixture. The present study proposes a comprehensive frequency-based approach to correlate the asphalt layer moduli obtained under two field and three laboratory loading modes. The field modes are vehicular and falling weight deflectometer (FWD) loading modes, and the laboratory ones are uniaxial compressive (UC), indirect tensile (IDT), and four-point bending (4PB) loading modes. The loading frequency is used as an intermediary parameter for correlating the asphalt layer moduli under different loading modes. The observations made at two field large-scale experimental pavements facilitate the correlation analysis. It is found that the moduli obtained via laboratory 4PB tests are pretty close to those of vehicular loading schemes, in contrast to those derived in UC, IDT, and FWD modes, which need to be adjusted. The corresponding adjustment factors are experimentally assessed. The applications of those adjustment factors are expected to ensure that the moduli measured under different loading modes are appropriately used in asphalt mixture pavement design and assessment.     

Protective effects of plasma alpha-tocopherols on the risk of inorganic arsenic-related urothelial carcinoma

Arsenic plays an important role in producing oxidative stress in cultured cells. To investigate the interaction between high oxidative stress and low arsenic methylation capacity on arsenic carcinogenesis, a case-control study was conducted to evaluate the relationship among the indices of oxidative stress, such as urinary 8-hydroxydeoxyquanine (8-OHdG), as well as plasma micronutrients and urinary arsenic profiles on urothelial carcinoma (UC) risk. Urinary 8-OHdG was measured using high-sensitivity enzyme-linked immunosorbent assay kits. The urinary arsenic species were analyzed using high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Plasma micronutrient levels were analyzed using reversed-phase high-performance liquid chromatography. The present study showed a significant protective effect of plasma alpha-tocopherol on UC risk. Plasma alpha-tocopherol levels were significantly inversely related to urinary total arsenic concentrations and inorganic arsenic percentage (InAs%), and significantly positively related to dimethylarsinic acid percentage (DMA%). There were no correlations between plasma micronutrients and urinary 8-OHdG. Study participants with lower alpha-tocopherol and higher urinary total arsenic, higher InAs%, higher MMA%, and lower DMA% had a higher UC risk than those with higher alpha-tocopherol and lower urinary total arsenic, lower InAs%, lower MMA%, and higher DMA%. These results suggest that plasma alpha-tocopherol might modify the risk of inorganic arsenic-related UC.