Pr0.6-xNdxSr0.4FeO3-δ电极材料的光谱及性能研究

以柠檬酸-硝酸盐自蔓延燃烧法合成了ABO₃型钙钛矿结构的Pr_0.6-xNd_xSr_0.4FeO_3-δ(x=0.0～0.6)系列稀土复合氧化物粉体。利用傅立叶变换红外光谱(FTIR)和激光共焦拉曼光谱(LRS)对产物的晶体结构进行了表征。分别采用热膨胀仪测定烧结陶瓷体的热膨胀系数(TEC)；TG-DTA记录材料的热稳定性；XRD研究阴极材料与中温电解质Sm_0.2Ce_0.8O_1.9(SDC)及La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ(LSGM)的化学相容性；SEM观察阴极/电解质复合材料的断口形貌。结果表明，该系列样品在高、低温热循环过程中化学稳定、晶型稳定；在室温至1 100 ℃范围内的平均热膨胀系数为1.16 × 10^-5 K^-1，与SDC及LSGM的热膨胀系数十分接近。阴极/电解质混合粉体1 200 ℃煅烧10 h，XRD未检测到新物质；SEM显示复合层断面界面清晰，没有相互扩散现象。该体系有望成为以SDC或LSGM为电解质的中温固体氧化物燃料电池合适的阴极材料。     

半导体激光器温控电路分析与测试

阐述了半导体热电致冷器(TEC)的基本工作原理,分析了TEC线性驱动和PWM驱动的原理以及采用PWM驱动的优点,介绍了PID温度补偿控制的原理,并设计了实验.采用相同的测试条件,对MAX1978、ADN8830和线性功率管进行了性能测试,实验数据表明温度控制电路采用PWM驱动功耗更小,全温(-40～60℃)控制效果更好.     

基于FPGA的半导体激光器温度控制系统设计

介绍了半导体激光器的温度控制原理,设计了基于FPGA的半导体激光器温度控制系统。系统采用数字温度传感器DS18820作为温度测量器件,TEC作为控温执行元件,并采用模糊控制算法、PWM机制来控制TEC的驱动电流从而实现温控。基于QuartusⅡ开发平台采用Verilog HDL设计了软件部分,最后进行了功能仿真。整个系统对硬件要求不高,实现简单。从仿真结果可以看出,控制系统能够满足半导体激光器温度控制的精度和稳定度的要求。     

Cold fiber solid-phase microextraction device based on thermoelectric cooling of metal fiber

A new cold fiber solid-phase microextraction device was designed and constructed based on thermoelectric cooling. A three-stage thermoelectric cooler (TEC) was used for cooling a copper rod coated with a poly(dimethylsiloxane) (PDMS) hollow fiber, which served as the solid-phase microextraction (SPME) fiber. The copper rod was mounted on a commercial SPME plunger and exposed to the cold surface of the TEC, which was enclosed in a small aluminum box. A heat sink and a fan were used to dissipate the generated heat at the hot side of the TEC. By applying an appropriate dc voltage to the TEC, the upper part of the copper rod, which was in contact to the cold side of the TEC, was cooled and the hollow fiber reached a lower temperature through heat transfer. A thermocouple was embedded in the cold side of the TEC for indirect measurement of the fiber temperature. The device was applied in quantitative analysis of off-flavors in a rice sample. Hexanal, nonanal, and undecanal were chosen as three off-flavors in rice. They were identified according to their retention times and analyzed by GC-flame ionization detection instrument. Headspace extraction conditions (i.e., temperature and time) were optimized. Standard addition calibration graphs were obtained at the optimized conditions and the concentrations of the three analytes were calculated. The concentration of hexanal was also measured using a conventional solvent extraction method (697+/-143ng/g) which was comparable to that obtained from the cold fiber SPME method (644+/-8). Moreover, the cold fiber SPME resulted in better reproducibility and shorter analysis time. Cold fiber SPME with TEC device can also be used as a portable device for field sampling.     

Development and commercialization of ionic-type photosensitive polyimides

Toray's ionic-type photosensitive polyimide, “Photoneece”, is widely used as an interdielectric and as a protection layer for microelectronics, because of its properties, such as the removal of photoreactive groups at low temperature, excellent thermal, mechanical and electrical film properties and excellent adhesion to various substrates. Toray has developed a new type of “Photoneece”, UR-5100, which is a low-stress photosensitive polyimide. In addition to a low thermal expansion coefficient (25 ppm/°C), “Photoneece” UR-5100 also features high resolution with an aspect ratio of more than 2.0 in 40 μm imaged film, and excellent mechanical properties in the cured film such as high elongation (>20%) and tensile strength (>200 MPa), even after 60 hr heat treatment at 350°C. “Photoneece” UR-5100 can be applied in multichip modules (MCMs), hybrid circuits, ICs and LSIs. In this paper the characterization and processing of this “Photoneece” UR-5100 are described.     

基于C8051F120的TEC温度控制系统

文章以C8051F120为核心,采用高精度的PT100温度传感器作为测温元件,在PID温度控制算法的基础上利用第三代制冷技术——半导体制冷设计了一种小型自动控温系统。可以将温度控制在3℃以下,控温精度可达±0.5℃。     

光纤熔接机加热扩芯制作模场适配器的研究

为了改善不同类型光纤熔接时的模场失配,通过调整普通光纤熔接机的熔接参数,对模场直径较小的光纤进行加热扩芯,实现了10/130μm大模场面积双包层光纤和6/125μm单模光纤的低损耗熔接,光纤耦合效率可达到91%,并成功应用于自主研发的小型1064nm光纤激光器中。对利用光纤熔接机加热扩芯制作模场适配器进行了理论分析,并用1064nm光纤激光器测量其实际传输损耗。实验结果表明:采用普通光纤熔接机,适当的调整熔接参数,可以有效地提高大模场面积光纤到单模光纤的耦合效率,为制作模场适配器提供了一种简单实用的方法。     

基于半导体制冷器的非均匀性校正

非均匀性是红外系统中影响图像质量的重要因素。为了更好地拟合探测器的响应曲线,充分发挥探测器的最佳性能,以获得良好的图像效果,在两点校正的理论基础上提出了一种更为实用的两点校正方法。通过单片机(MCU)控制半导体制冷器(TEC)以产生两个不同的校正温度点,系统分别读取在这两个温度点下所采集的两幅图像,利用两点校正算法计算探测器的响应率和暗电流。通过实验验证,这种校正算法实用,易于实现。     

L3中心径迹室顶点位置分辨的改进

运用两种方法对L3中心任迹漂移室的顶点位置分辨进行了改进,一种是利用高能量分辨的电子和高动量分辨的μ子测量,限定轻子径迹的曲率半径,对径迹进行重新拟合;另一种是对中心径迹室每半边单元的径迹零位置位移进行校正.结合两种改进方法将轻子的顶点位置分辨由原来的137μm提高到60μm.     

Integrated Acousto-Optical Temperature Sensor

In this work, we investigate the performance of a novel integrated acousto-optical temperature sensor fabricated in LiNbO₃ and operating with ultrashort light pulses (2 ps). Five parameters (time duration, bandwidth, time intensity maximum, frequency intensity maximum, and output energy on the output pulse converted for the TM mode, as a function of temperature) were observed for the switched pulse at the output of the sensor (TM mode) with and without the presence of an increasing linear self-phase modulation (SPM) profile. Comparing all analyzed parameters, one can conclude that the pulse intensity is presenting the larger variation (100.09%) as a function of the temperature change (24.5 to 400°C) in a configuration without profile. Considering the increasing linear SPM profile, all the analyzed parameters are presenting a significant increase in the percentile variations in the studied range of temperature (24.5 to 400°C). Comparing all the five parameters, in two configurations (with and without the use of linear SPM profile), one can conclude that the time intensity maximum showed to be the most suitable parameter as measurement to be accomplished in a schematic detection for the temperature sensing in the range 24.5 to 400°C. We can conclude that the sensitivity of the AOTS is improving in the configuration with the increasing nonlinearity profile (β = 2) and for higher temperature.