GaN氢化物气相外延生长系统的设计与制作

根据GaN氢化物气相外延生长(HVPE)的原理,设计制作了双温区卧式HVPE系统．根据实际生长中出现的问题和CaN样品的测试情况,对系统进行了逐步的调试和改进．     

金属有机化学气相沉积法制备钛酸铅铁电薄膜

利用低压ＭＯＣＶＤ工艺分别在（００１）取向的ＬａＡｌＯ_３，ＳｒＴｉＯ_３和重掺杂硅单晶衬底上制备ＰｂＴｉＯ_３铁电薄膜，并通过Ｘ射线衍射谱对薄膜的微结构进行分析．Ｘ射线θ－２θ扫描显示硅衬底上得到了ＰｂＴｉＯ_３多晶薄膜，另两种衬底上得到了择优取向的ＰｂＴｉＯ_３薄膜．ＬａＡｌＯ_３衬底上的ＰｂＴｉＯ_３薄膜有ａ和ｃ两个取向，也就是薄膜中存在着９０°畴结构，而生长在ＳｒＴｉＯ_３衬底上的ＰｂＴｉＯ_３薄膜中只存在ｃ方向的择优取向．由于薄膜的尺度效应，发现ｃ轴晶格常数与块材相比均缩短．Ｘ射线的φ扫描验证了后两类薄膜的外延特性，利用同步辐射的高强度和高能量分辨率用摇摆曲线方法研究了这两种外延薄膜的品质，进一步证明了ＳｒＴｉＯ_３衬底上的ＰｂＴｉＯ_３薄膜的单畴特性．利用重掺杂的硅衬底作底电极，测量显示直接生长于硅衬底上的ＰｂＴｉＯ_３多晶薄膜具有良好的铁电性能 关键词：     

FOURIER TRANSFORM FAR INFRARED SPECTRA AND NORMAL COORDINATE ANALYSIS OF FIFTEEN RARE-EARTH OXALATE HYDRATES

The Fourier transform far infrared spectra of oxalate hydrates of whole rare-earth series except Pm and Sc are investigated in the range of 100-400 cm~(-1). The assignment of vibrational frequencies is made on the basis of normal coordinate analysis using our NORVIB program. The model used for the hghter elements of the lanthanide series (La to Eu) is based on the crystal structure of Nd_2(C_2O_4)_3. 10H_2O, in which each lanthanide ion is surrounded by nine O atoms, six from three oxalate ions and three from Water molecules.The model adopted for the heavier elements of the lanthanide series (Gd to Lu) and Ytterbium is based on the crystal structure of Yb_2(C_2O_4)_3· 6H_2O, in which each ion is surrounded by eight atoms, six from three oxalate ions and two from water molecules. The variation of the metal-ligand frequencies and force constants with the atomic numbers of lanthanides is plotted and discussed.     

二胺扩链剂对RIM聚氨酯－脲弹性体的结构与性能的影响

采用实验室小型ＲＩＭ机制备了一组不同芳香二胺扩链的嵌段聚氨酯－脲（ＰＵＵ）弹性体，借助于ＩＲ、ＤＳＣ、ＤＭＴＡ、ＳＥＭ以及拉伸试验等测试手段对其结构与性能进行了研究．通过比较由ＭＤＡ、ＤＥＴＤＡ以及ＣＡＭＤＡ三种不同活性和结构的芳香二胺扩链剂与二异氰酸酯反应形成的硬链段对ＲＩＭＰＵＵ弹性体的结构与性能的影响，表明：ＭＤＡ基ＲＩＭＰＵＵ中软、硬链段微区界面作用指数很小，微相分离程度却很大，其性能最差；ＤＥＴＤＡ基ＲＩＭＰＵＵ弹性体有理想的界面作用指数，以及适当的微相分离程度，其性能位于三者之中最佳．ＤＭＴＡ研究证实在一定的温度范围内ＤＥＴＤＡ基ＲＩＭＰＵＵ的模量稳定性最好．     

Progressive filling partitioning and mapping algorithm for Spark based on allocation fitness degree

The job execution mechanism of Spark was analyzed,task efficiency model and Shuffle model were established,then allocation fitness degree (AFD) was defined and the optimization goal was put forward.On the basis of the model definition,the progressive filling partitioning and mapping algorithm (PFPM) was proposed.PFPM established the data distribution scheme adapting Reducers’ computing ability to decrease synchronous latency during Shuffle process and increase cluster the computing efficiency.The experiments demonstrate that PFPM could improve the rationality of workload distribution in Shuffle and optimize the execution efficiency of Spark.     

半定矩阵秩极小的非凸精确松弛

本文主要研究半定矩阵秩极小问题(P)的非凸精确松弛及其性质.首先,为求解问题(P),我们引入其Schatten p-范数(0＜p＜1)松弛,记为(Sp).其次,通过定义半定限制等距常数和半定限制正交常数,我们给出了问题(P)有唯—解的充分条件.最后,利用半定限制等距性质,我们给出了问题(P)和(Sp)有相同唯一解的充分条件.特别地,对任意0＜p＜1,我们还得到—个一致的精确恢复条件.     

LTE通信基站市电引入设计中应该考虑的问题

LTE通信基站市电引入的设计是基站建设的首要环节,直接关系到基站供电的可靠性和安全性,对通信网络的安全运行起到关键的作用。基站市电引入的设计多数由施工单位自行设计施工,造成基站市电引入方式出现较混乱的局面,不合理的设计施工会造成巨大的经济损失。做好基站市电引入设计,使市电引入方式合理化、简单化,在加大可靠性和安全性的基础上,降低投资成本,减少维护量能保障通信畅通,提高经济效益。     

A temperature sensor based on the splicing of a core offset multi-mode fiber with two single mode fibers

In this paper, a temperature sensor based on the splicing of a core offset multi-mode fiber with two single mode fibers is proposed and demonstrated experimentally. The temperature sensing principle is analyzed and related experiment is performed. By controlling the core offset and splicing length of the specialty multi-mode fiber (SMMF), two sensors with different temperature sensing properties are obtained, and experimental results show that the temperature sensitivity can be up to 48.76 pm/°C in the range of 25—95 °C. Moreover, it has many advantages, including small size, high sensitivity, and simple structure. So it can be used in potential temperature sensing applications, such as industrial production, biomedical science, power electronics, and so on.     

高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱筛查和确证纺织品中的致癌染料

建立了高效液相色谱-线性离子阱/静电场轨道阱高分辨质谱(HPLC-LTQ/Orbitrap MS)筛查和确证生态纺织品中致癌染料的方法。样品在水浴(95 ℃)中用吡啶/水(1/1, v/v)振荡(150 r/min)提取,上清液过聚四氟乙烯(PTFE)滤膜后,CAPCELL PAK C₁₈色谱柱(100 mm×2.0 mm, 5 μm)分离,以乙腈和5 mmol/L乙酸铵水溶液(含0.01%甲酸)、乙腈和5 mmol/L乙酸铵水溶液分别作为正、负电喷雾离子化(ESI)模式的色谱流动相梯度洗脱。在m/z 200~800范围内进行一级质谱全扫描。以准分子离子峰的精确质量数和提取的色谱图峰面积进行筛查分析和定量,以保留时间和数据依赖扫描(data-dependent scan)模式获得的子离子质谱图进行定性确证。9种染料的质量准确度小于5×10^-6(5 ppm),线性良好,相关系数大于0.99,方法检出限为0.125~25 mg/kg。3个添加水平的回收率范围为62.13%~116.28%,相对标准偏差小于15%。应用该方法检测了棉、涤纶及混纺纤维等20余件纺织品样品中的致癌染料残留。该方法准确、可靠。