Scalable Flexible Hybrid Membranes with Photonic Structures for Daytime Radiative Cooling

Passive radiative cooling technology can cool down an object by reflecting solar light and radiating heat simultaneously. However, photonic radiators generally require stringent and nanoscale‐precision fabrication, which greatly restricts mass production and renders them less attractive for large‐area applications. A simple, inexpensive, and scalable electrospinning method is demonstrated for fabricating a high‐performance flexible hybrid membrane radiator (FHMR) that consists of polyvinylidene fluoride/tetraethyl orthosilicate fibers with numerous nanopores inside and SiO₂ microspheres randomly distributed across its surface. Even without silver back‐coating, a 300 µm thick FHMR has an average infrared emissivity >0.96 and reflects ≈97% of solar irradiance. Moreover, it exhibits great flexibility and superior strength. The daytime cooling performance this device is experimentally demonstrated with an average radiative cooling power of 61 W m^?2 and a temperature decrease up to 6 °C under a peak solar intensity of 1000 W m^?2. This performance is comparable to those of state‐of‐the‐art devices.     

基于FPGA技术的智能导盲犬

利用FPGA技术设计出一种智能导盲犬,可以有效减少费用和提高实用性,克服普通导盲犬训练费用高、培养时间长的缺点。设计基于Altera公司的DE1开发系统,在使用中进行实时图像处理,波形处理,以及多进程并行处理;利用超声波测速测距系统以及图像采集系统采集外部环境信息,经综合处理系统对信息进行处理分析,并进行多模块输出,利用人性化语音提示向使用者反馈当前信息,利用受控电机控制导盲犬的行动。系统还可通过GPS模块进行短消息发送,亲属可及时掌握盲人的行踪,可实现多种实用功能。     

光时域反射光纤光栅传感系统中双激光器的驱动设计

为了扩大应变测量的范围,提出了使用两个分布反馈式(DFB)激光器作为光时域反射光纤光栅(OTDR-FBG)传感系统的光源的方法,并设计了相应的纳秒脉冲驱动电路和温控电路,得到两个激光器的驱动脉冲宽度分别为3.10 ns和3.18 ns,脉冲幅值分别为4.40 V和4.08 V,温度控制电路精度达到±0.04 ℃。经测试得到的纳秒脉冲和温控精度满足OTDR-FBG传感系统的要求。     

基板预变形下激光立体成形直薄壁件应力和变形的有限元模拟

针对单道多层的直薄件激光立体成形过程,建立了基板预变形和无预变形条件下的3D参数化有限元模型,进行了应力和变形的瞬时热弹塑性有限元模拟分析。模拟结果表明,基板预变形处理影响成形件应力和变形的分布与大小,并可减轻基板的翘曲变形。预变形下基板下表面具有初始拉应力点的残余应力值比无预变形要小,基板与熔覆层接触的界面中间位置残余应力也小于无预变形的情况,直薄壁件最大残余压应力所在位置也发生变化。在两模型中,熔覆层两侧边缘位置变形严重,而中间位置变形较小。熔覆层首层的沉积对基板变形量影响最大,后续熔覆层的沉积对基板变形量影响程度逐渐减小并最终趋于稳定。成形前对基板进行适当的预变形处理可以有效控制成形件变形和改善应力分布。     

用于宽带偏振无关耦合器的双芯光子晶体光纤

提出一种可用于宽带偏振无关光定向耦合器的新型双芯光子晶体光纤(PCF),利用全矢量有限元方法分析了光纤结构参数对其光学特性的影响,得到了一组优化的双芯PCF结构参数,满足易于制作、易于接续和接续损耗低等应用要求,在此基础上对光纤结构进行了改进,进一步降低了制作难度,基于该光纤可以设计出在1.26～1.625μm范围内分光比误差小于1%、两偏振态分光比误差小于0.2%的50:50耦合器,并在现有实验条件下,试制了近似结构的双芯PCF。     

基于ARM嵌入式图像处理平台的太阳跟踪系统

基于计算机视觉原理,以ARM微控制器为核心构建嵌入式图像处理平台,实现了对太阳的实时跟踪。系统采用CMOS图像传感器采集太阳图像,通过微控制器计算太阳角度,通过串口控制转台,实现对太阳的高精度跟踪。同时,与视日运动规律相结合,保证系统的可靠性。试验表明,该系统在降低系统能耗的同时,能可靠有效地跟踪太阳运动。     

Campus View: An Innovative Location and Context-Aware Video Sharing Application on Smart Phone

Mobile devices have steadily gained acceptance as a multimedia platform, not only that, one of the most valuable pieces of contextual information for an intelligent mobile application is the user??s location. The university campus is an interesting application environment for location-based and context-aware mobile services: wherever the students are, they are eager to announce to others and want to know what happens in the university campus, even alumni always care about the latest in his or her campus. The Campus View, what is described in this article, is a smart-phone based context and location-aware video sharing mobile application implemented on Android 2.1. It first gives a full panorama to one Chinese university campus, which will provide a campus overview and variations to alumni and potential students. Different from Street-view of Google which was only created once and demands not to drive anywhere more than once, our campus panorama is timely updated by our DIYed Street-view camera. What??s more, the application users inside the campus can use it to recode the latest happenstance and then upload the video short with Geo-information to the server. The recoded video short will be further shared as a H. 264 stream attached to a specific panorama. This paper presents the development framework of Campus View application and an evaluation of key framework components to assess their consumption of mobile device??s resources.     

热红外相机光机系统设计

以气象观测应用为目标,提出一种基于非制冷微测辐射计的热红外波段相机光学设计方案,该光学系统焦距60 mm,光谱范围8～14 μm,视场角7°.综合三片分离式结构和双高斯光学结构设计了红外物镜,优化后物镜成像质量达到衍射极限.进行了物镜的无热化结构设计,分析结果表明在-20℃～60℃范围内,物镜成像弥散斑直径接近爱里斑直...     

基于第三方控制的量子双向传态

提出一个基于第三方控制的量子双向传态方案：通信双方Alice、Bob和控制方Charlie事先共享一个六粒子团簇态,通信开始后,Alice、Bob分别对自己拥有的部分粒子作Bell基联合测量（BSM）,若控制方同意双方通信,则对自己拥有的粒子对作测量,将粒子所处的态公布;通信双方根据控制方公布的测量结果,对各自的某些粒子作适当的幺正变换,即可在这些粒子上重建对方要传的态。由于加入了第三方的控制,双向传态的安全性得到了提高。     

基于BP网络的血液气味识别模型的建立

以血液气味样品的气相色谱质谱分析结果为基础,建立了一个基于BP人工神经网络的血液气味识别模型,并利用Matlab计算平台对此模型进行了优化、训练和测试.此模型的网络结构为9×13×1,隐含层传递函数为tansig,输出层传递函数为logsig,训练函数为trainrp.优化后的模型对血液样品的正确识别率为100％.