温度对ABS塑料冲击行为的影响

本文研究了温度对ABS塑料抗冲击性能和断口形貌的影响。结果指出:ABS抗冲击强度随试验温度下降而降低。低温冲击断面由断裂源、光滑区、放射区和粗糙区组成,随温度升高,光滑区和放射区尺寸增大;高温下的冲击断面由断裂源,应力发白区、放射区和粗糙区组成,随温度升高,应力发白区尺寸增大。观察到两种类型抛物线形貌,结合断口分析探讨了温度对抗冲性能的影响。     

Influence of slip system combination models on crystal plasticity finite element simulation of NiTi shape memory alloy undergoing uniaxial compression

The influence of various slip system combination models on crystal plasticity finite element simulation of Ni Ti shape memory alloy subjected to uniaxial compression deformation is investigated according to three combinations of slip systems, including combination of {010}100and {110}111slip modes, combination of {110}100and {110}111slip modes and combination of {110}100, {010}100and {110}111slip modes, which consist of 18, 18 and 24 slip systems, respectively. By means of simulating mechanical response,strain distribution, stress distribution and Schmid factor, it can be found that in terms of simulation accuracy,combination of {110}100and {110}111slip modes is in good agreement with combination of {110}100,{010}100and {110}111slip modes. The contribution of {110}100slip mode to plastic strain is primary in plastic deformation of Ni Ti shape memory alloy, whereas {010}100slip mode, which makes small contribution to plastic deformation, can be regarded as the unfavorable slip mode. In the case of large plastic strain, the {010}100slip mode contributes to the formation of(001) [010] texture component, while {110}100and {110}111slip modes facilitate the formation of γ-fibre(111) texture.     

杈干现象对南方红豆杉树冠形态、生长和形质的影响

【目的】探明杈干对南方红豆杉树冠形态、生长和形质的影响,揭示杈干作用于树木生长、树冠形态的分级机制,分析树冠形态与生长和形质间关系的杈干效应,明确杈干木和未杈干木类型的树冠形态调控措施。【方法】在福建省明溪县南方红豆杉15年生人工林分中设置标准地,调查分析杈干木、未杈干木的树冠形态及生长、形质间差异,统计不同杈干木类型红豆杉胸径、树高、冠幅、冠形率、树冠率的分级分布,通径分析不同杈干木类型红豆杉树冠形态特征与生长形质间的关系。【结果】杈干显著抑制南方红豆杉的冠长、冠形率、树冠率,但对冠幅无显著性影响;杈干显著促进南方红豆杉地径、胸径、树高、单株材积、枝下高以及生长形质总体表现,但对树干尖削度、圆满度无显著性影响。不同杈干木类型间胸径、树高、冠形率、树冠率的分级分布明显不同,胸径、树高、单株材积、总体表现与树冠形态特征间关系也明显不同。【结论】杈干明显改变南方红豆杉胸径、树高、冠形率、树冠率的分级分布,杈干对胸径、树高、冠形率、树冠率的影响是通过改变高、低分级区间的分布比例来实现。杈干改变南方红豆杉胸径、单株材积、总体表现与树冠形态特征间关系,其相应的树冠形态调控措施不同。促进总体表现时...     

螯合剂辅助水热合成DyF3纳米晶

采用螯合剂辅助水热法,在较低的温度下合成了DyF3纳米晶。通过调节反应条件,实现了对产物形貌的控制合成。用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)等对样品的形貌和晶体结构进行表征。结果表明:当反应温度为180℃,反应时间为48h,反应溶液pH=3,添加EDTA螯合剂的浓度为1.67μmol/L的条件下,能够制备出晶体形貌均一的截角八面体DyF3纳米晶体。     

光子晶体光纤压力传感器输出信号监测技术研究

光子晶体光纤压力传感器在各种压力环境监测中具有极其重要的作用.文章提出了光子晶体光纤压力传感器系统模型和输出信号检测方案,设计了一种用多片高速运放并联的方式来对PCF压力传感器输出电信号的放大,采用双极型定时器5G555新型整形电路对PCF压力传感器输出电信号进行有效的整形,为了满足PCF压力传感器对信号的相位和幅频特性以及计算工具的条件等多方面的因素,提出了一种用MAX293实现的无源BiQuad滤波电路对传感器输出电信号进行滤波.采用我们提出的放大、整形和滤波电路系统可以优良检测PCF压力传感器输出信号.     

基于〔V_(16)O_(38)(CO_3)〕~(6-)钒氧簇化合物的水热合成与结构表征

利用水热方法合成了新化合物〔N(ien)3〕〔2N(ien)(2H2O)2〕〔(CO3)V16O38〕·3H2O,对化合物进行了X射线单晶结构分析、元素分析、红外光谱、X射线光电子能谱等测试,结果表明,该化合物属于单斜晶系,C2/c空间群·〔V16O3(8CO3)〕6-簇阴离子是由16个畸变的VO5四方锥通过20个三桥氧、2个双桥氧和16个端氧以共棱和共顶点方式连接而成的钒氧笼,笼的中心容纳着CO32-,而镍-乙二胺配离子作为平衡阳离子存在.     

Investigation of silicon on insulator fabricated by two-step O~+ implantation

In this paper,we investigated the dose window of forming a continuous buried oxide(BOX) layer by single implantation at the implantation energy of 200 keV. Then,an improved two-step implantation process with second implantation dose of 3×1015 cm-2 was developed to fabricate high quality separation by implanted oxygen(SIMOX) silicon on insulator(SOI) wafers. Compared with traditional single implantation,the implantation dose is reduced by 18.2%. In addition,the thickness and uniformity of the BOX layers were evaluated by spectroscopic ellipsometry. Defect-free top Si as well as atomic-scale sharp top Si/buried oxide interfaces were observed by transmission electron microscopy,indicating a high crystal quality and a perfect structure of the SOI fabricated by two step implantation. The top Si/BOX interface morphology of the SOI wafers fabricated by single or two-step implantation was also investigated by atomic force microscopy.     

各向异性与量子点平衡形态及应变分布

向异性对于半导体量点光学和电学性能有较大影响.本文基于向异性弹性理论的有限元方法,研究了金字塔组织生长半导体量点平衡态与应变分随外延材料向异性系数的变化规律,讨论了向异性系数与应变弛豫的关系,出了同向异性系数的量点体系平衡态及其应力、应变、静水应变及双轴应变分等.结果可作为进一研究量点光电性能及制备量点的理论参考.     

指纹图象局部纹线周期的准确提取

指纹图象的局部纹线周期是预处理中构造滤波函数（如Aabor滤波器）的重要参数,在先求得指纹图象局部纹线方向的基础上,分析了局部纹线周期错误对滤波的影响及造成错误的原因,提出了一种基于数学形态学的准确求取局部纹线周期的方法。该方法在大量试验中取得良好应用效果。     

水稻动态株型材料的遗传特性

从引进的水稻材料中发现了在生育前期叶片披垂，后期叶片直立的动态株型材料泸香90A.动态株型材料90A分别与正常株型恢复系蜀恢527和泸香恢1号杂交，F1代均表现显性，即动态型，杂交组合的F2代群体发生分离，动态型植株与正常型植株的比例表现为3：1．初步的遗传分析表明，上述动态株型属单基因显性遗传．