基于大功率LED扩展光源的均匀光斑光辐射模拟器设计

基于边缘光线原理和光学扩展量守恒思想,结合复合抛物面聚光器和轴对称自由曲面透镜,设计并研制了大功率发光二极管扩展光源的反射/折射准直器.运用Tracepro软件对系统进行光束追迹模拟仿真和实验,研制出均匀光斑的光辐射模拟器.模拟器输出发散角为±12°光束,测量距离出射面50cm处光屏的光斑,在尺寸为14cm×14cm的光照范围内,测得光斑水平方向中心线上的光度均匀度优于4.1%,竖直方向中心线上的光度均匀度优于3.8%.     

2014年最有趣的20项光电子技术盘点

1.增强现实显示器大千世界,光电子装置发展的最突出形式之一是头戴眼镜式显示器。然而,谷歌眼镜自面市以来一直都没有很成功的发展,为什么呢?嗯,是因为奇怪的外观;它只有一个单一的、侧边小屏幕;而用户使用时常常会发生斗眼。北卡罗来纳大学教堂山分校(UNC)和Nvidia研究中心的研究人员开发出一个眼镜显示器的设计,可以解决上述所有问题:增强现实眼镜是透明的,可以是3D立体的,至少看起     

A fluorescent probe for Hg2+sensing in solutions and living cells with a wide working pH range简

In this paper, 2-carboxybenzaldehyde rhodamine B thiohydrazine(1) was synthesized and developed as a fluorescent probe to recognize Hg2+in DMF/H2 O(1:9, v/v) solution with high selectivity. The probe can be applied to the quanti?cation of Hg2+with a linear concentration range covering from 1.0×10-7mol/L to 1.0×10-5mol/L(R2= 0.9985) and a detection limit of 4.2×10-8mol/L. The experiment results show that the response of probe 1 to Hg2+is pH-independent in a wide range from 4.0 to 9.0. Moreover, the probe 1 exhibits excellent selectivity toward Hg2+over other common metal cations. Most importantly, the probe can be employed to monitor Hg2+in living cells using fluorescent imaging technique with satisfied results.     

Influence of Gd doping on the absolute quantum efficiency and lifetime of EuxGd1-x（TTA）3phens

Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.     

The effects of ultrasound frequency and power on the activation energy in Si-KOH reaction system

The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz （interval by 20kHz） and 10-50W （interval by 10W）, respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.     

关于一元酸准确滴定判据的商榷

化学分析教科书中给出的弱酸能被准确滴定的条件是cKa≥1.0×10-8。本文根据这一判据的来源(滴定突跃≥0.3pH单位),对一元酸体系的滴定情况进行了严格数学处理。计算结果表明,只有同时满足弱酸的浓度c1.0×10-3mol/L和cKa≥1.0×10-8条件下,弱酸才能被准确滴定。对于浓度极稀的酸溶液(c≤1.4×10-4mol/L),无论强酸还是弱酸都不能被准确滴定。对教材很少涉及的不同浓度酸碱互相滴定的情况也给出了有价值的结论。     

高韧性合金钢断裂韧性及疲劳裂纹扩展门槛值的联合试验方法

在柴油机曲轴、连杆等关键零部件的可靠性设计和失效评估中,断裂韧性及疲劳裂纹扩展门槛值分别是衡量材料抵抗裂纹失稳扩展和裂纹开始扩展的重要指标．但是,对于高韧性合金材料,难以通过常规试验所推荐的厚度确定平面应变断裂韧性,而门槛值的测定通常不但非常耗时,且难以直接应用于不同循环特性的实际结构．本文针对高韧性合金钢34CrNi3MoA,提出一种将断裂韧性和疲劳裂纹扩展门槛值试验合二为一的试验方法,即用同一个试件可以同时测定门槛值和断裂韧性．利用断裂韧性关于试件厚度的渐近特性,以几种较薄试件的试验,确定平面应变状态下的断裂韧性．试验结果还表明,裂纹扩展门槛值的试件厚度依存性可以忽略,并给出了任意循环特性（应力比）下的门槛值计算公式．     

节理煤体低温损伤机理及影响范围研究

节理普遍存在于地下煤储层中,是煤层气存储和运移的主要通道。为了研究冻融作用下煤体自身含水饱和度的不同,对节理结构损伤和液氮作为煤体的制冷剂逆传热至-45℃作用范围的影响,利用低温保存箱为不同含水饱和度煤样提供-45℃低温环境,对煤样进行循环冻融交叉实验;并建立以液氮作为制冷剂的传热模型,进行单周期低温加载数值模拟。结果表明：(1)煤样表面以及内部节理扩展量随着低温循环冻融周期的增加而逐渐增大,单轴抗压强度逐渐降低;煤样表面维度逐渐从二维向三维转化、表面及内部节理结构损伤程度加剧;(2)煤样节理结构损伤程度随含水饱和度的增加而增大,100%饱和度时,煤样循环冻融41周期后破碎;(3)单周期传热模型随着含水饱和度的升高,影响范围变小,且传热时间变长,100%含水饱和度下煤体传热至-45℃的传热半径仅为2.77m,所用时间为2531.2s,表明含水饱和度制约着传热半径及传热时间,含水饱和度越高,制约越明显。     

内窥式共聚焦成像系统分析

基于点扩展函数和傅立叶光学理论,推导出系统的相干传递函数,并详细研究了光纤对轴向分辨率的影响.研究结果表明：该系统为相干成像系统,系统的轴向分辨率随光纤半径A的增加而降低.最后,搭建了一套内窥式共聚焦成像系统,并测得光栅样品的共聚焦图像.实验结果表明,该系统具有良好的分辨率.     

高铁锻钢制动盘热疲劳裂纹扩展仿真及寿命评价

巨大的制动热能导致高铁制动盘面出现热斑或热点,形成沿径向扩展的热疲劳裂纹,严重危及行车安全.通过仿真获得热疲劳裂纹扩展规律,据此制定出合适、经济的检测周期,具有重要意义.基于断裂力学理论,采用扩展有限单元法和自主研发的裂尖网格加密技术,得到热点形成规律,植入半椭圆形裂纹进行热疲劳断裂仿真,得到制动速度为400 km/h...