Soluble silica assisted synthesis and luminescent characteristics of yellow emitting CaSrSiO4:Eu2+ phosphors for warm white light production

To meet the challenges and additional requirements towards the development of white LED׳s with utmost efficacy, a sol–gel approach is adopted wherein a water soluble silicon compound is used as a silica source. The phosphor material obtained is subjected to detailed structural, morphological and luminescent studies. The results obtained show that the XRD patterns of Eu²⁺ doped CaSrSiO₄ phosphors are in good agreement with the CaSrSiO₄ (ICSD no. 49660) whose structure is orthorhombic. The output of the luminescence studies clearly portrays a broad yellow emission between 450 and 750 nm with a peak at ~600 nm under the broad excitation range. This confirms its efficient emission towards the development of a warm white light using blue LEDs. A red shift in the peak emission wavelength was observed for the prepared samples. This longer shift in wavelength can be credited to the sol–gel method adopted and is not offered by the conventional solid state reaction method. A warm white emitting LED was fabricated by combining near ultraviolet LED (400 nm) chip with our sol–gel synthesized CaSrSiO₄:Eu²⁺ phosphor. The CIE chromaticity coordinates (0.44 and 0.41), color correlated temperature (CCT) <4000 K, color rendering index (CRI) >80 provide their emission potentiality in the warm white light region.     

聚丙烯挤压机在高熔融指数的开车分析

掌握挤压机高、低熔融指数开车的参数是聚丙烯车间工艺专业和设备专业所要攻关的重要课题之一。本文根据聚丙烯车间2#装置挤压机CMP335在高速挡高熔融指数开车时出现的问题和从DCS获得的挤压机开车数据,分析影响挤压机开车的主要因素,结合不同指数的挤压机开车工艺参数所呈现出来的挤压机运行规律,提出可行的开车方法,如优化挤压机开车参数和调整挤压机的开车步骤等方法,实现挤压机不同牌号的开车。     

风城超稠油蒸汽吞吐后期转蒸汽驱开发方式研究

在新疆风城油田超稠油油藏注蒸汽吞吐开发后期,蒸汽驱开发方式是提高采收率的有效途径.研究表明,蒸汽驱过程体现了驱泄复合作用,即蒸汽超覆在油层上部形成蒸汽腔,加热原油在驱动力和重力双重作用下从生产井采出,由此可形成直井小井距蒸汽驱、直井与水平井组合蒸汽驱、水平井与水平井组合蒸汽驱3种吞吐后期接替方式,先导试验达到了预期效果,进一步拓展了蒸汽驱适用的地质条件和组合方式,对同类超稠油油藏的开发具有借鉴意义.     

模糊层次分析法在港西地区新近系储层大孔道识别中的应用

油藏水驱油开发后期其储层特征和流体性质与开发前期相比发生了较大的变化,大孔道的存在使得疏松砂岩油藏注入水循环流动,波及体积降低,水驱油效果变差,严重影响了水驱油藏开发效果。使用常规识别方法识别水淹层大孔道具有很大困难。通过对港西地区地质条件和储层特征的研究,提取水驱油藏大孔道形成的因素及判别特征,提出运用模糊决策理论识别大孔道的方法,通过决策模型的建立和对各测井曲线各特征数值的多层次因素分析,确定大孔道的划分方式和识别标准。将该方法运用于对港西地区部分储层的大孔道识别,取得了良好的效果。     

基于PLC控制技术和气压传动控制技术的汽车前悬架与转向轮螺纹装配设备研发

在装配汽车前悬架与转向轮时需要拧紧螺纹,一旦操作不当就会出现前倾角过大的缺陷,加快车轮胎的磨损,降低小轴承及轮毂紧固螺母的使用寿命。对此,本文设计了一种基于PLC控制技术和气压传动控制技术的装配设备,能有效避免上述问题。     

大功率LED散热用微通道铝基板的有限元仿真

对带微通道的铝基板上封装的不同功率LED,用Comsol Multiphysics软件对其温度场进行了有限元模拟,重点研究了微通道的孔大小、孔间距、绝缘层的厚度和热导率对基板散热性能的影响,结果表明:铝基板厚度为1.5mm左右,微通道方形孔,孔长0.8mm,孔间距0.8mm,绝缘层厚度50μm,热导率1.5 W/(m·K),为最佳散热性能铝基板.微通道铝基板封装3W灯珠与普通铝基板和氮化铝基板相比,热阻分别下降了5.44和3.21℃/W,表明微通道铝基板能更好地满足大功率LED散热的需求.     

LED外延片上芯片静电击穿的测试分析

利用静电仪和HBM模型研究了GaN基LED外延片上芯片的抗静电性能,并根据pn结势垒电容的特性,对实验结果进行了分析.实验结果表明,缺陷击穿与外延片的工艺有着密切的关系;随着外延片上芯片尺寸的增大,其抗静电能力也随之增强.     

InGaN/GaN多量子阱LED的电特性研究

针对InGaN/GaN多量子阱LED,分析了占据能态高于势垒的载流子和低于势垒的载流子参与的电流输运机制,从而推导出对应能态电流输运机制下的电流-电压关系,以及理想因子与温度的变化规律.实验结果证实,在低注入强度下,由材料缺陷引入的深能级辅助隧穿输运机制占主导,电流电压特性符合相应的推导结果,随着注入强度的增大,参与扩散-复合输运机制的载流子逐渐增加,温度对输运机制的影响逐渐增大.     

Failure analysis on reflector blackening between lead frame electrodes in LEDs under WHTOL test

Blackening induced lumen decay in a QFN LED after WHTOL reliability test was reported and analyzed in this paper. A new LED blackening failure mechanism was proposed based on solid experimental results. We concluded that the failure process underwent delamination between lead frame and reflector polymer composites followed by chemical penetration, composite corrosion, silver migration, and finally caused blackening failure. Delamination and corrosive de-flash agent were the key factors for the failure mode. Besides, we also estimated the influence of the failure to the optical performance through simulation. Apart from other reported factors, this study highlighted that both composite corrosion and Ag migration could generate serious illumination decrease as well. The outcome of this study is valuable for LED manufacture and quality control in the future.     

带虚拟LED功能的多屏控制系统设计

本文设计了一种带虚拟LED功能的多屏控制系统。介绍了虚拟LED功能的实现原理和实现方法;阐述了系统启动和虚拟LED功能的实现流程。将虚拟LED功能集成到多屏控制系统中,可以解决指挥中心大屏幕和LED显示屏两套设备、两套软件的问题。带虚拟LED功能的多屏控制器使得大屏幕系统的安装更方便、操作更简便、稳定性更高。