用二元光学技术制作计算全息波面变换元件

基于计算全息原理与二元光学技术设计制作了应用于机载平视显示器（HUD）中的计算全息波面变换元件,该元件具有较高的衍射效率,一块二元相位型计算全息元件的衍射效率比一般计算全息图的衍射效率提高了四倍,并能产生传统光学元件不能实现的光学波面,如非球面,环状面和锥面等,制作工艺简单,复制简便。     

氧化铝负载多孔沸石球的制备及其在As 吸收中的应用

通过粉末烧结法制备了多孔沸石球, 烧结温度为1100～1300 ℃, 烧结时间为1 h. 所用原料为天然斜发沸石粉末, 烧结所得多孔沸石球的直径为3～5 mm, 宏孔孔径约为1 mm, 抗压强度可达1.703×10⁶ Pa. 通过对比烧结前后沸石的X射线衍射谱和红外光谱, 对烧结机理进行了初步分析. 采用BET气体吸附法测得该多孔沸石的比表面积为7.053m⁶/g. 通过SEM 分析也观察到了该多孔沸石具有优良的大孔和宏孔结构. 在上述多孔沸石表面负载活性氧化铝, 得到了对砷离子具有较强吸附能力的活性氧化铝负载多孔沸石球, 并对其吸附机理进行了研究. 研究表明, 该沸石球在水处理方面有广阔的应用前景.     

高超声速自适应激波针数值研究

针对传统的与钝体轴线共线安装的固定式激波针方法在有攻角状态所存在的问题, 在前人工作基础上得到一种新型高超声速飞行器减阻/降热方法------自适应激波针方法. 将该方法应用于三维高超声速轴对称钝锥外形以及扁平楔外形, 并采用数值模拟的方法对其进行了概念验证. 在0○~120○攻角范围内, 对不同L/D参数的激波针外形流场以及前缘壁面的压力、热流分布等进行了对比分析. 结果表明, 这种新型自适应激波针方法无论在无攻角还是有攻角状态, 均可有效降低高超声速飞行器头部壁面的压力和热流, 可以有效解决传统激波针方法在较大攻角情况状态下失效的问题.      

EFFECTS OF 2-TUNNEL AND 3-TUNNEL FIXATION ON BIOMECHANICS OF TIBIOFEMORAL JOINT

基于正常膝关节4个屈曲角度(0°, 25°, 60°, 80°)下的磁共振(MR)图像数据, 建立正常/两隧道固定/三隧道固定内侧半月板移植术后的胫股关节模型. 对各屈曲角度下的4种模型分别施加单一轴向压载和压扭组合载荷进行有限元仿真, 得到各模型在2种载荷作用下的应力及位移分布. 提取关节软骨、半月板表面的等效应力以及半月板的最大位移进行对比分析, 得到内侧半月板移植术后两/三隧道固定对胫股关节中软骨及半月板的影响. 总体上讲内侧半月板移植中的三隧道固定要优于双隧道固定, 更利于胫股关节恢复正常的应力特性.     

大型液体火箭姿控与跷振大回路耦合动力学建模与分析

大型液体火箭结构模态的空间化分布特征导致结构振动、姿态运动和推进系统液路脉动存在相互耦合,进而影响传统姿控回路的稳定性. 针对大型液体火箭, 充分考虑姿态控制系统对箭体姿态动力学和弹性振动的影响, 以及箭体结构弹性振动与推进系统的耦合作用(跷振(POGO)), 建立了姿控与跷振大回路耦合模型. 该模型包含了推进系统、结构系统与姿控系统之间的耦合因素, 可进行姿控-结构-推进大回路耦合机理研究. 该模型具有非奇异的优点, 可以直接用于频域分析和时域仿真. 基于该模型研究了我国某型号液体捆绑火箭推进系统参数——泵增益和蓄压器能量值对姿态运动与结构振动稳定性的影响. 研究得出, 泵增益和蓄压器能量值的变化不仅导致了结构振动的不稳定, 而且也导致了姿态运动的发散. 因此, 对于大型液体捆绑火箭, 推进系统与姿控系统之间存在不可忽略的耦合作用, 在设计姿控系统时, 有必要考虑推进系统对姿控系统稳定性的影响.      

Anti-wear beam effects on gas-solid hydrodynamics in a circulating fluidized bed

Anti-wear beams installed on water walls of circulating fluidized bed(CFB) boilers are one of the most effective ways to protect against water-wall erosion.Beam effects from,for example,beam size and superficial gas velocity were investigated on gas-solid hydrodynamics in a CFB test rig using CFD simulations and experimental methods.The downward flow of the wall layer solids is observed to be disrupted by the beam but is then restored some distance further downstream.When falling solids from the wall layer hit the anti-wear beam,the velocity of the falling solids decreases rapidly.A fraction of the solids accumulates on the beam.Below the beams,the falling solids have reduced velocities but upward-moving solids were observed on the wall.The effect of the beam increases with width and superficial gas velocity.Wear occurs mainly above the beam and its variation with width is different above to below the beam.There is an optimum width that,when combined with beam height,results in less erosion.     

基于相位恢复的光学元件面形检测技术研究

利用标量衍射的角谱理论,研究了基于两幅光强分布的相位恢复算法,并将此算法应用到光波的波前及光学元件面形的检测中。实验研究了球面光波波前的相位恢复及面形检测,给出了恢复波前与理想波前之间的偏差,采用求Zernike系数的广义逆矩阵的方法,用程序实现了光学元件面形的Zernike拟合。     

Synthesis of a bulky and electron-rich derivative of SEGPhos and its application in Ru-catalyzed enantioselective hydrogenation of beta-ketoesters

The synthesis and resolution of a bulky and electron-rich derivative of SEGPhos and its application in Ru-catalyzed asymmetric hydrogenation reaction of beta-ketoesters are reported. Up to 99.5% ee was achieved. Under solvent-free reaction conditions, acetoacetates could be reduced with good enantioselectivity and high efficiency; a TON of 20 000 was obtained within 3.5 h. The results obtained were comparable to those when SEGPhos was applied.     

H2O和N2的谱线碰撞增宽的理论计算

采用Ｔｅｊｗａｎｉ修正的Ａｎｄｅｒｓｏｎ模型和Ａｓｈｏｋ、Ｔｈｏｍｐｓｏｎ计算水的转动能级和波函数的最新程序，计算了水和Ｎ２碰撞谱线增宽，获得了较高量子数的半宽数据     

Revealing Isolated M−N3C1 Active Sites for Efficient Collaborative Oxygen Reduction Catalysis

Single atom catalysts (SACs) are of great importance for oxygen reduction, a critical process in renewable energy technologies. The catalytic performance of SACs largely depends on the structure of their active sites, but explorations of highly active structures for SAC active sites are still limited. Herein, we demonstrate a combined experimental and theoretical study of oxygen reduction catalysis on SACs, which incorporate M−N₃C₁ site structure, composed of atomically dispersed transition metals (e.g., Fe, Co, and Cu) in nitrogenated carbon nanosheets. The resulting SACs with M−N₃C₁ sites exhibited prominent oxygen reduction catalytic activities in both acidic and alkaline media, following the trend Fe−N₃C₁ > Co−N₃C₁ > Cu−N₃C₁. Theoretical calculations suggest the C atoms in these structures behave as collaborative adsorption sites to M atoms, thanks to interactions between the d/p orbitals of the M/C atoms in the M−N₃C₁ sites, enabling dual site oxygen reduction.