Development of the Technique for Fabricating Submicron Moire Gratings on Metal Materials Using Focused Ion Beam Milling

A focused gallium ion （Ga＋） beam is used to fabricate micro/submicron spacing gratings on the surface of porous NiTi shape memory alloy （SMA ）. The crossing type of gratings with double-frequency （25001/mm and 50001/mm） using the focused ion beam （FIB） milling are successfully produced in a combination mode or superposition mode. Based on the double-frequency gratings, high-quality scanning electron microscopy （SEM） Moird patterns are obtained to study the micro-scale deformation of porous NiTi SMA. The grating fabrication technique is discussed in detail. The experimental results verify the feasibility of fabricating high frequency grating on metal surface using FIB milling.     

First-Principles Study of Structural and Electronic Properties of Layered B2CN Crystals

Based on the hexagonal BN structure, six possible layered B~ CN structures are constructed. Their total energies, lattice constants as well as electronic properties are calculated using the ab initio pseudopotential density functional method within the local density approximation. The calculated results show that the B2 CN-V configuration with AA stacking sequence is the most stable among the six B2CN layered structures. The characteristics of electronic structures indicate that the B2 CN-V shows metallicity, which mainly comes from -B1-C-B1-C- chains.     

交联萘沥青的组成与结构特征

萘与硫在较低温度下交联聚合，制得了可溶性好、残炭值高、软化点较低，流动性良好的交联萘沥青。结构分析发现，此沥青分子量分布较窄，主要由三到四个萘分子交联而成，推测其反应机理，估计聚合物经萘环侧位交联成环而形成长链状硫杂环类结构。     

微波强场中的光谱激发现象

本文报道了元素，化合物和放电灯在微波强场产生的激发现象。介绍了一种在微波强场中产生原子发射光谱的新方法。采用作者自行改制的微波激发装置，即可使固态的元素和化合物产生光谱辐射，也可使各种放电灯和气体光谱管得以激发，用一种装置实现了几种装置的功能，对于该方法存在的问题，文中也作了一定的说明。     

LiTaO_3和LiNbO_3中超声传播时间及等效弹性模量的温度系数

应用脉冲回波重合法(Pulse-Echo-Overlap Method),在—100℃— 100℃温度范围内,精确地测量了钽酸锂和铌酸锂晶体中八种体波模式超声传播时间随温度的变化关系,并由此计算了声速温度系数和等效弹性模量的一级、二级温度系数。     

旋转压电纳米梁的振动分析

本文基于非局部弹性理论，对旋转压电纳米梁模型的振动进行了分析．首先由哈密顿原理导出旋转压电纳米梁的动力学控制方程及相应的边界条件；再通过微分求积法对控制方程和两类边界条件进行离散；最后通过数值计算分析振动特性．通过改变旋转角速度、轮毂半径、非局部参数以及外部电压分析它们对压电纳米梁振动频率的影响关系．数值结果表明这些参数对压电纳米梁固有频率有不可忽略的影响，本文进一步讨论了旋转角速度对结构模态的影响．     

动失速型非定常分离涡结构的控制

本文对动失速型非定常分离涡结构的控制方法，在低速风洞中应用相平均测压技术进行了实验研究。在二元平板模型中部安装一作俯仰振荡的扰流板产生动失速型分离涡，在其上游安装另一用作控制的小扰流板。实验结果表明，应用前置的振荡小扰流板可影响并改变动失速分离涡的强度和对流特性。在最有利的控制相位下，涡吸力峰可降低４８％，涡对流时间可以推迟０．１９周期。对于间歇式振荡扰流板，采用相位提前控制方式比相位滞后控制方式更有效。     

高效液相色谱法测定全血中直链烷基苯磺酸钠

提出了高效液相色谱法测定全血中直链烷基苯磺酸钠同系物的含量。全血样品用酸性提取溶液稀释,过Bakerbond SPE C18固相萃取小柱,经甲醇-乙酸-水(49+2+49)混合溶液淋洗后用甲醇-氨水(98+2)混合溶液洗脱。经纯化后的洗脱液在Wakopak WS AS-Aqua(250 mm×4.6 mm,5μm)柱上进行分离,流动相为乙腈与水(60+40)混合溶液,检测波长为228 nm。5种n-ABS同系物的C10~C14的质量分数在10.0~100.0 ng.g-1范围内与其峰面积呈线性关系,全血中各同系物回收率为78%~107%;日内相对标准偏差(n=5)≤10%,日间相对标准偏差(n=5)≤13%。     

Proposal of metal bellows-based fiber Bragg grating accelerometer

A metal bellows-based fiber Bragg grating(FBG) accelerometer is proposed and experimentally demonstrated. The optical fiber(containing the FBG) is pre-tensioned,and the two ends of the optical fiber are fixed directly from the shell to the inertial mass. In this design,the FBG is uniformly tensioned to obtain a constant strain distribution over it. By employing this configuration,the FBG always has a sharp reflection characteristic with no broadening in its reflection spectrum during wavelength shifting. Dy...     

关于Rankin-Selberg问题: Riesz余项的高次均值

设$\Delta_1(x;\varphi)$ 表示Rankin-Selberg问题中的第1 Riesz余项, 研究其高次积分均值. 利用大值估计及其他技巧得到了$\Delta_1(x;\varphi)$的3次、4次和5次积分均值的渐近公式.