空间光学遥感器主镜加工过程中疲劳寿命研究

针对空间光学遥感器主镜镜面加工过程中,磨盘与主镜间磨削动作往复运行引起的主镜柔性支撑结构疲劳寿命问题,通过建立主镜组件的有限元模型,利用MSC.Fatigue软件按应力-寿命(S-N)法对主镜组件进行了疲劳寿命分析,确定了支撑结构的薄弱部位,并对仿真过程进行了误差分析,讨论了影响仿真结果的各个因素.对比热真空试验和动力学试验前后主镜镜面面型数据,验证了支撑结构加工、设计参量的合理性.通过疲劳寿命仿真分析,可以有效预示光学结构在加工过程中的疲劳情况,为空间光学遥感器结构的设计、加工提供理论依据和参考.     

Enhancement of upconversion luminescence of YAlO3:Er3+ by Gd3+ doping

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.     

Design of undercuts and dipole stabilizer rods for the CPHS RFQ accelerator

As part of the design and machining of the RFQ accelerator in the Compact Pulsed Hadron Source (CPHS) project at Tsinghua University, the design process of the undercuts and dipole stabilizer rods is presented in this paper. In particular, the relationship between the inter-vane voltage slope and the local frequency of the undercut section is described quantitatively. With the identification of modes existing in the cavity, the specific parameters are optimized by the SUPERFISH and MAFIA codes. In addition, the water-cooling requirement of the dipole stabilizer rods is briefly discussed.     

First-principles study of lithium intercalated bilayer graphene

Lithium intercalated bilayer graphene has been investigated using first-principles density functional theory calculations. Results show that there exist AB and AA stacking sequences for bilayer graphene in which the latter is more favorable for the Li storage and the former will evolve into the latter with the intercalation of Li ions. The relationship between the interlayer distance of two graphene sheets and the intercalated capacity of Li ions is discussed. It is found that structural defect is identified to store Li ions more favorably than pristine bilayer graphene and an isolated C atom vacancy in bilayer graphene can capture three Li ions between two graphene sheets.     

防护板尺寸对Whipple防护结构撞击损伤影响的实验研究

通过高速撞击实验,探讨了采用小尺寸防护板的可行性。实验中采用的Whipple结构由尺寸变化的1 mm厚防护板（前板）和尺寸固定的3 mm厚舱壁板（后板）组成,防护板与舱壁板间隔10 cm。防护板为边长分别为8、12、16和20 cm的方形2A12铝合金板,舱壁板为边长为20 cm的方形5A06铝合金板。实验过程中均采用直径为4 mm的铝合金球形弹丸,撞击速度为1.45~1.71 km/s。实验结果表明:Whipple防护结构在舱壁板被击穿的概率大于0.8的条件下和击穿概率为0的条件下的极限速度以及舱壁板临界击穿条件下的速度都与防护板尺寸无关;并且,防护板前后表面击穿孔的直径及击穿孔侧壁的倾斜角也与防护板尺寸无关;但是,在速度相同的条件下随着板尺寸的增大,防护板板面的最大挠度增大,而且,防护板挠曲面的凸凹方向也由单一的凹向变成凸凹方向交替出现;随着速度的增加和板尺寸的增大,防护板最大挠度的增量减小。     

卷曲折叠充气管展开实验研究

运用气垫导轨模拟微重力条件,通过实验研究了卷曲折叠充气管在不同充气速率条件下的展开动力性能,以及不同的充气方式、不同的卷曲形式等对充气管展开性能的影响,研究表明,随着充气速率、充气方式和卷曲形式的变化,充气管端部的动力性能、管内“充气铰”的大小和展开的半径以及＂增压滞后＂现象等都发生相应的改变;且充气速率越大,充气管展开端的速度就越大。最后,本文还对不同材料的充气管的展开性能进行了研究,发现充气管内壁用钢卷尺加强,成为充气硬化（STR）管后,不仅能提高充气管的屈曲承载力,还能改善充气管的展开性能。     

岱衢族大黄鱼不同组织的同工酶谱

于2006年11月,在象山港采集30尾网养岱衢族大黄鱼,采用聚丙烯酰胺凝胶垂直电泳方法,研究分析了岱衢族大黄鱼眼睛、肌肉、肝脏、肾脏、脾脏、心脏、胸鳍、鳃和脑9种组织中16种同工酶（LDH、ADH、MDH、ME、SOD、POD、EST、GAD、ALP、ATP、FDH、SCD、IDH、GDH、ACP、GcDH）的表达情况,发现除IDH、GDH、ACP、GcDH 4种酶只显示微弱且不稳定的区带外,其他酶类在各组织中都显示出清晰稳定的酶谱,且这些酶在表型、分布和活性上均表现出高度的组织特异性,与各组织的生理功能相一致.     

蛋白质三级结构对蛋白质内部形成紧密接触对速率的影响

通过蛋白质分子内两残基间距的概率分布函数P（r）,计算了641个蛋白质分子内近程和远程紧密接触对的形成速率．分析了不同蛋白质结构,不同紧密接触对半径以及DNA的绑定对速率的影响．结果表明：不同结构类型蛋白近程和远程紧密接触对的形成速率的变化趋势恰好相反．近程紧密接触对的形成速率ks随着n（n≡｜j—i｜）的增大而增大,远程紧密接触对的形成速率kL随着n的增大而减小,并且远程紧密接触对的形成速率AL满足AL（n）∝^-γ的关系、γ值随着紧密接触对半径α的增大而变小,当α=0．6nm时,全α蛋白的γ值等于0．382,α/β蛋白的γ值等于0．343,全β和α＋β蛋白的γ值等于0．218．DNA的绑定使蛋白质分子内近程和远程紧密接触对的形成速率都减小．     

A New Type of Seiberg-Witten Map and Its Application

Deformation quantization is a powerful tool to deal with systems in noncommutative space to get their energy spectra and corresponding Wigner functions, especially for the case of both coordinates and momenta being noncommutative. In order to simplify solutions of the relevant *-genvalue equation, we introduce a new kind of Seiberg-Witten-like map to change the variables of the noncommutative phase space into ones of a commutative phase space, and demonstrate its role via an example of two-dimensional oscillator with both kinetic and elastic couplings in the noncommutative phase space.