MoSi_2(001)表面的氧吸附行为

运用第一原理密度泛函理论方法,首先计算了MoSi_2各清洁表面的表面能,(001)Si-|-Si断面具有较低的表面能,是MoSi_2最可能的解理面;通过生成能及键布居分析研究了单氧原子、双氧原子及氧分子在(001)Si-|-Si断面的吸附行为,发现单氧原子在空位处吸附最稳定,此时O极易与Si结合,得到的Si-O-Si键长及键角与SiO_2的非常接近,表明低浓度下O极易与表面的Si结合生成SiO_2;双氧原子发生空位+顶位吸附时O原子除与Si有强作用外,可与Mo有一定相互作用;氧分子以平行的方式接近空位最有利于吸附,此时氧分子最易分解为氧原子,发生氧原子在空位的吸附.     

源气体对沉积的a-C∶F∶H薄膜结构的影响

采用微波电子回旋共振等离子体化学气相沉积(MWPECRCVD)方法,使用不同的源气体(CHF3CH4,CHF3C2H2,CHF3C6H6)体系制备了aC∶F∶H薄膜.由于CH4,C2H2,C6H6气体在等离子体中的分解反应不同导致了薄膜的沉积速率和结构上的差异.红外吸收谱的结果表明,用C6H6CHF3作为源气体沉积的薄膜中几乎不含H,而用C2H2CHF3所沉积的薄膜中的含氟量最高,其相应的CF振动峰位向高频方向偏移.薄膜的真空退火结果表明,aC∶F∶H薄膜的热稳定性除了取决于薄膜的CC键浓度外,还与CC键 关键词： 氟化非晶碳膜 电子回旋共振化学气相沉积 红外吸收光谱     

金属材料三维断裂韧度厚度效应的有限元模拟

随着金属材料大壁厚结构件在工程中的广泛应用,对其断裂韧度的厚度效应研究具有重要的科学意义和工程价值.该研究基于有限元和实验相结合的方法,对金属材料断裂韧度的厚度效应进行预测.首先,通过一组薄壁厚金属材料标准三点弯曲试验得到试样失效时的临界载荷值,并利用内聚力模型与基于虚拟裂纹闭合技术的裂纹扩展模拟方法得到裂纹扩展时的单元临界能量释放率.随后,以此临界能量释放率作为裂纹扩展的启裂准则门槛值,通过有限元计算得到不同试样厚度下裂纹启裂时的裂尖断裂参数随着厚度的变化规律.最后,为了验证有限元模拟结果的准确性,该研究进行了另外两组不同厚度下三点弯曲试样的断裂韧度试验,并将试验结果与有限元结果进行了对比,验证了有限元所模拟的断裂韧度厚度效应的准确性.该研究旨在,通过薄壁厚三点弯曲试样的实验结果结合有限元模拟工作,即可实现金属材料断裂韧度的整个厚度效应曲线,为任意厚度下金属材料断裂韧度预测提供一种可靠的研究方法,有益于缩减试验成本,为大壁厚工程结构件的失效预测提供依据.     

光子晶体垂直腔面发射850nm波长激光器研究

文章报道了国内首次研制成功的光子晶体垂直腔面发射850nm波长激光器, 实现了连续电注入激射.发现器件能否激射直接依赖于光子晶体结构参数,而激光器的阈值、输出功率、输出模式等与光子晶体的晶格常数、占空比、腔的大小等因素有关.     

Processing for laser radar range images

Imaging laser radar can give intensity and range images, which provide integrated 3-dimensional (3D)information about objects. However, dropouts and range anomalies exacerbate range images, which makes their background cluttered and target blurred. For background suppression, a new algorithm that combines intensity image and its mean is presented. By using this algorithm to process actual laser radar range images, most background noises are suppressed. According to range anomalies characteristics, multitemplate selection order mean filtering algorithm is presented and used for actual ladar range images where the distance between two targets is 77 m. This algorithm obtains the clear range image in which the interval of two objects is 75 m. The result shows that the processing algorithm is correct and effective.     

拟南芥高盐耐受突变体的筛选与鉴定

采用floral dip方法，将雌激素诱导激活标签系统PER16ACT转入拟南芥中，最终获得了18000株T-DNA插入株系．通过挑取能够在250mmol／L NaCl条件下萌发的拟南芥突变体，从200000粒该突变体库T2代种子中筛选到一株高盐耐受性突变体hst1(highs salt tolerant 1)，进一步分析表明hst1在种子萌发阶段和幼苗生长阶段都对NaCl具有耐受性，在没有盐胁迫的条件下，hst1同野生型没有明显的区别。     

脂肪酶催化苯甘氨酸甲酯两对映体的氨解反应

从6种脂肪酶中筛选出对苯甘氨酸甲酯具有较高氨解反应活性及较高对映体选择性的脂肪酶Novozym435,并研究了铵盐量、温度、有机溶剂及初始水活度对两种对映体的氨解反应的影响,当以叔丁醇为反应介质,反应温度为30℃,铵盐量为15.6mg,初始水活度为0.75时,酶表现出较高的氨解反应活性和对映体选择性。     

Structure Tuning of Line-Defect Waveguides Based on Silicon-on-Insulator Photonic Crystal Slabs

We present fabrication and experimental measurement of a series of photonic crystal waveguides. The complete devices consist of an injector taper down from 3 μm into a triangular-lattice air-hole single-line-defect waveguide with lattice constant from 410nm to 470nm and normalized radius 0.31. We fabricate these devices on a silicon- on-insulator substrate and characterize them using a t unable laser source over a wavelength range from 1510 nm to 1640nm. A sharp attenuation at photonic crystal waveguide mode edge is observed for most structures. The edge of guided band is shifted about 30nm with the 10nm increase of the lattice constant, We obtain high-efficiency light propagation and broad flat spectrum response of the photonic crystal waveguides.     

基于电磁拓扑的配电网络雷电过电压分析

将适用于复杂系统各个节点电磁响应同步求解的电磁拓扑方法引入到配电网络雷电过电压问题的分析中。首先,给出了传输线网络的BLT方程及其元素构建方法;然后,通过一个复杂的配电网络对电磁拓扑的分析流程进行了详细说明,并重点展示了理想节点散射矩阵的求解步骤。结果表明：电磁拓扑方法可以应用在配电网络节点雷电过电压的分析中,其计算结果与CST的结果非常吻合,且耗时远远低于CST。     

Processing for laser radar range images

Imaging laser radar can give intensity and range images,which provide integrated 3-dimensional (3D) information about objects.However, dropouts and range anomalies exacerbate range images, which makes their background cluttered and target blurred.For background suppression,a new algorithm that combines intensity image and its mean is presented.By using this algorithm to process actual laser radar range images, most background noises are suppressed.According to range anomalies characteristics,multitemplate selection order mean filtering algorithm is presented and used for actual ladar range images where the distance between two targets is 77 m. This algorithm obtains the clear range image in which the interval of two objects is 75 m.The result shows that the processing algorithm is correct and effective.