Fast electro-optical mode in photo-aligned reflective deformed helix ferroelectric liquid crystal cells

The electro-optical behavior of deformed helix ferroelectric liquid crystal in reflective mode is described in this paper. The electrically controlled reflectance has been measured at subkilohertz driving voltage frequency for different polarizations of the incident light and compared quite successfully with the simulation results.     

The stress relief mechanism in laser irradiating on porous films

Stress relief effect is believed to be the main reason why the porous structure films have high laser induced damage threshold. But there is little systematic theoretical investigation of this view. This essay adopts spherical coordinate model to calculate the temperature and stress distribution in the film and analyzes the local stress redistribution after phase transformation or crush happens. The influences of porosity and pore radius on stress redistribution have been studied. The results show that: for the case of only local crush occurrence, the changes of porosity and pore radius have little influence on the stress relief effect. For the films with low porosity, the formed thermal stress cannot be alleviated effectively. When local phase transformation happens, the permeation action of high pressure fluid can reduce the local high pressure in the phase transformation zone; on the other hand, it can make the high pressure fluid permeate to film's surface and cause surface tensile stress increase. The final effect is the competitive result of these two mechanisms. Overall, when the permeation action of phase transformation materials happens, the higher porosity or larger pore radius, the higher capability of films to resist laser damage.     

A novel Si-based photodetector with flat-top and steep-edge spectral response

To meet the requirement of the dense wavelength-division-multiplexed (DWDM) system and optoelectronic integrated circuit, we design a Si-Based InGaAs photodetector, which is fabricated by bonding InGaAs/InP photodetector on a Si-Based dielectric film Fabry–Perot filter. The photodetector can exhibit an extremely good flat-top and steep-edge spectral response through designing the structure of Si-Based dielectric film Fabry–Perot filter. The simulation result of phtodetector demonstrates that the spectral response linewidth, ?at-top and steep-edge characteristics of these photodetectors are suitable to be used in 50 GHz, 100 GHz, 200 GHz DWDM system.     

Structural, elastic, and electronic properties of orthorhombic NH3BH3: An ab initio study

At the generalized gradient approximation (GGA), the elastic constants of the orthorhombic phase of NH₃BH₃ were calculated with plane-wave pseudo-potential method. Our calculation showed that the orthorhombic phase NH₃BH₃ is a loose and brittle material, as well as hard to be deformed, also we calculated the elastic anisotropies and the Debye temperatures from the elastic constants. And from the band structure and density of state (DOS), we concluded that NH₃BH₃ is a wide-gap semiconductor and the band gap is almost 6.0 eV. The bonds between N atoms and H atoms show a strong covalent characteristic, B atoms and H atoms form ironic bonds, and so as to the B-N bonds. Electrons from the B atoms are absorbed by the H atoms around the B atoms, and the H atoms display electronegativity.     

氘氘中子产额铟活化诊断方法

提出了活化法测量DD中子产额的实验方法,该方法可提高DD中子产额测量的精度。方法基于铟同位素115In与DD中子的非弹性散射反应,活化反应释放的射线被HPGe探测器记录,根据活化系统标定灵敏度推算出中子产额。分析了探测器记录的活化射线数与中子产额间的关系。介绍了一套活化测量的系统设计。通过蒙特卡罗方法模拟了活化样品出射的射线数与样品厚度的关系,模拟结果表明:样品厚度取为1 cm可兼顾活化效率和测量精度。在加速器上对铟活化样品进行了标定实验,实验结果表明:在聚变中子产额大于2109的实验中可使用铟活化诊断方法,中子产额测量的相对标准误差在10%以内。随着聚变中子产额的不断提高,铟活化测量中子产额的精度可进一步提高。     

便携式近红外光谱仪的苹果糖度模型温度修正

样品温度对近红外光谱有很大影响,在近红外技术评价水果品质的实际应用时,需要修正温度变化对模型预测结果的影响。便携式近红外光谱仪采集不同温度下(0～30℃)苹果的漫透射光谱,采用二阶导数和卷积平滑进行预处理。选取20℃下代表性样本的光谱数据,建立基准PLS模型。斜率/偏差法分别计算苹果糖度PLS模型在0,10和30℃下的修正方程。分析结果表明:斜率/偏差法对0,10和30℃下外部样本预测结果进行修正,预测精度得到显著提高,其修正前后的Q值分别为0.525cv 0.810,0.680cv0.822,0.669cv 0.802。温度修正模型可以有效提高预测精度,也扩展了近红外仪器的适用性,为自主研发便携式近红外光谱仪提供参考。     

惯性约束聚变点火靶候选靶丸特点及制备研究进展

获得能量增益实现点火是目前激光惯性约束聚变领域研究的主要方向和标志性成果. 在点火靶的设计中有多种可能的候选靶丸,包括碳氢掺杂锗、铍掺杂铜、聚酰亚胺、 碳化硼和金刚石靶丸,其中碳氢和铍靶丸是最主要的候选靶丸.文中主要总结了几种候选靶丸的优缺点及目前研制现状.在国外,碳氢靶丸是目前点火靶的首选靶丸. 与铍靶丸相比,不存在明显的微结构缺陷,制备较容易;靶丸光学透明, 适宜于燃料分层和表征;靶丸在制备上更容易达到点火靶要求. 美国的碳氢点火靶靶丸基本达到了设计要求,这些要求包括几何尺寸、壳层密度、 壳层缺陷、表面光洁度、掺杂水平和杂质含量等.我国的点火靶靶丸研究还处在起步阶段.     

氯苯的同步辐射光电离研究

利用真空紫外同步辐射和反射式飞行时间质谱仪对氯苯进行了光电离研究,通过测量各离子的光电离效率(PIE)曲线,得到了氯苯的电离势为(9.11±0.05)eV及两种主要碎片离子C6H+5和C4H+3的出现势分别为(12.96±0.05)和(16.27±0.05)eV.结合有关文献的热力学数据,推导出C6H5Cl+、C6H+5及C4H+3的离子生成焓及一些键的解离能.实验获得了118.0nm同步辐射光电离下氯苯的质谱图.     

δ函数的定义及其性质

对δ函数的传统定义及由此引起的奇性展开讨论,说明了在经典意义下δ函数可以被看成是弱收敛函数序列的弱极限以及阶跃函数Heaviside函数的导数;最后,借用泛函分析中广义函数的概念给出了δ函数的严格数学定义,并就其性质进行了讨论．     

用于中温烟气脱硫的新型钙基脱硫剂

研究了高效钙基脱硫剂的制备原理,在石灰水合反应生成氢氧化钙和提高比表面积两个关键环节上,采用了一系列方法提高钙利用率,获得突破性进展。进一步研究了中温范围内脱硫温度对钙利用率的影响,得到700℃时超过95％的钙利用率,为发展中温干式烟气脱硫工艺开辟了新的道路。