大功率白光LED倒装焊方法研究

介绍了一种大功率、高亮度LED倒装散热封装技术。采用背面出光的蓝宝石LED芯片,倒装焊接在有静电放电（LED）保护电路的硅基板上。该封装技术针对传统LED出光效率低下和散热问题做出了改进,有效提高了LED芯片的寿命,降低了制造成本。     

太阳耀斑爆发对我国夏季雷暴活动的影响

本文研究了我国１８５个气象测站１９７１～１９８０年夏季雷暴活动频数对２级以上太阳耀斑的影响。江、浙、皖、赣一带耀斑爆发后雷暴平均频数比爆发前提高（４０～４３）％；而华北地区和东北地区则降低（１９～３１）％。经Ｓｔｕｄｅｎｔ－ｔ检验，耀斑爆发前后雷暴频数平均值的差异显著性分别通过了优于１０－５、５×１００３及１０－４的置信度检验．     

中纬度地区粒子沉降和太阳耀斑对甚低频传播的影响分析

通过观测俄罗斯Alpha甚低频导航台到中纬度地区(新乡)之间的甚低频(VLF)信号的相位变化数据,发现在2002-07-17-2002-07-20期间,VLF信号发生了多次相位超前现象,观测到在2002-07-19和2002-07-20发生了高能粒子沉降事件,并分析出此次事件是由2002-07-17和2002-07-18发生的太阳耀斑引起.通过与美国发布的GOES卫星数据进行对比,发现两者的数据有很好的一致性.粒子沉降和太阳耀斑都会使甚低频信号的相位发生相位超前.粒子沉降大多数情况发生在极区,本次在新乡地区观测到高能粒子沉降,是一次极为宝贵的观测数据,对研究中纬度地区的高能粒子沉降有很大的作用.     

Tricolor white emitting phosphor co-doped with Eu, Dy in SiO2 matrix

A Eu, Dy co-doped SiO2 matrix, white emitting phosphor was prepared by the sol-gel technique. Strong red, green and blue emissions located at 618 nm, 573 nm and 400-550 nm were observed under UV laser excitation at room temperature. Such techniques as FT-IR and TGA-DSC were used to measure the microstructure of the luminescent material. The influence of the preparation techniques on the luminescence property of the Eu, Dy co-doped SiO2 matrix, such as anneal temperature, anneal time, dried atmosphere and the components of the matrix, was systematically studied, and the luminescence mechanism was interpreted. The red emission is the strongest when annealed at 750℃. However, blue emission appears when annealed at 700℃ and is the intensest at 900℃. For the samples dried in vacuum, Eu^3＋ is more easily deoxidized to Eu^2＋ at lower temperatures, because the samples dried in the air compared with that dried in vacuum need higher temperature to form network structures. Only the SA and SAB matrix annealed at 850℃ had blue emission in the four matrices （SA, SAB, SB, S） xerogel and the emission in the SAB matrix was stronger than that in the SA matrix. This may be due to the eutectic phase formed by the oxide boron, alkaline oxide and alumina in the SAB matrix, which constructs network structures and stabilizes the emission center and enhances the blue emission.     

Where do flare ribbons stop?

The standard flare model,which was proposed based on observations and magnetohydrodynamic theory,can successfully explain many observational features of solar flares.However,this model is just a framework,with many details awaiting to be filled in, including how reconnection is triggered.In this paper,we address an unanswered question:where do flare ribbons stop?With the data analysis of the 2003 May 29 flare event,we tentatively confirmed our conjecture that flare ribbons finally stop at the intersection of separatrices(or quasi-separatrix layer in a general case)with the solar surface.Once verified,such a conjecture can be used to predict the final size and even the lifetime of solar flares.     

孔边残余应变与疲劳循环次数相关性实验

对有限宽中心带孔拉伸试样进行疲劳试验.在疲劳加载过程中,按一定的疲劳周次在零载荷状态下停机,并采集试件表面上预先制备的白光散斑图.再应用数字散斑相关技术测量了不同疲劳循环次数后孔周的残余变形场,并给出了孔边最大残余应变与疲劳循环次数的关系曲线.