镍基单晶高温合金短时时效过程中取向变化的原位研究

利用TEM和XRD原位研究了一种镍基单晶高温合金在时效过程中的取向变化.研究发现固溶-时效热处理后的初始样品内部不同γ′相之间存在~4°的小角度晶界.对材料在950℃下进行10 min短时时效处理,原位TEM和XRD结果表明γ′相的取向偏离初始取向~5°,且该取向变化在降温之后也不会完全恢复;该短时升、降温过程使γ′相的取向集中度增加.     

Taming Charge Transport in Semiconducting Polymers with Branched Alkyl Side Chains

The solid‐state packing and polymer orientation relative to the substrate are key properties to control in order to achieve high charge carrier mobilities in organic field effect transistors (OFET). Intuitively, shorter side chains are expected to yield higher charge carrier mobilities because of a denser solid state packing motif and a higher ratio of charge transport moieties. However our findings suggest that the polymer chain orientation plays a crucial role in high‐performing diketopyrrolopyrrole‐based polymers. By synthesizing a series of DPP‐based polymers with different branched alkyl side chain lengths, it is shown that the polymer orientation depends on the branched alkyl chain lengths and that the highest carrier mobilities are obtained only if the polymer adopts a mixed face‐on/edge‐on orientation, which allows the formation of 3D carrier channels in an otherwise edge‐on‐oriented polymer chain network. Time‐of‐flight measurements performed on the various polymer films support this hypothesis by showing higher out‐of‐plane carrier mobilities for the partially face‐on‐oriented polymers. Additionally, a favorable morphology is mimicked by blending a face‐on polymer into an exclusively edge‐on oriented polymer, resulting in higher charge carrier mobilities and opening up a new avenue for the fabrication of high performing OFET devices.     

CdTe and HgTe surface growth kinetics for molecular and metalorganic molecular beam epitaxy

The surface growth kinetics of CdTe and HgTe have been investigated during molecular and metalorganic molecular beam epitaxy. The surface growth kinetics was studied through in-situ measurements of the growth rate as a function of flux ratio and substrate temperature on the (001), (111)B, and (211)B CdTe surface orientations. For the (001) and (111)B CdTe growth kinetics, the existence of low binding energy surface precursor sites was proposed for both molecular and atomic growth species before lattice incorporation. Intensity oscillations were observed during HgTe growth on misoriented (111)B surfaces and during CdTe growth on the (211)B orientation. The (211)B surface reconstructions displayed both vicinal and singular surface characteristics, depending on the growth flux ratio.     

基于预处理的气动退化图像边缘定位

为了便于解决气动退化图像因图像模糊退化不易进行复原处理的问题,提出了一种气动退化红外图像的边缘定位算法。首先对退化图像进行基于像素疑似度的去噪预处理;然后使用Canny算子进行了边缘定位,进而对边缘区域进行了边缘修复和滤波处理。通过对多组气动退化图像的仿真实验及与多种边缘检测算法的对比分析表明,算法具有较好的边缘定位能力,较好地去除了气动退化图像模糊的问题,图像质量得以恢复,同时算法复杂度较低。     

The Adjustment on Service Structure and Strategic Orientation of Postal Service

1　Introduction1 1　PresentSituationofPostalServiceStructure　Table 1indicatesthatin 1 992theproportionofletters postservicerevenuecouldreachashighas1 7 2 %andtheNewspapersandPeriodicals (NandP)distributionrevenueoccupied 31 8% ,whilein2 0 0 2the proportionsofthetwodroppedinto1 1 0 % .Themajorreasonforthesituationisthatthedevelopmentofthenewservices,especiallythedevelopmentofEMSand postalsavingsservice .Sincetheletter postservicehasalwaysbeenmonop olizedbyChinapost,thepostoccupiesadomi…     

c轴择优取向ZnO薄膜RF溅射工艺研究

通过射频磁控溅射在Si(100)基片上制备了ZnO薄膜,该文着重研究了磁控溅射中各生长参数如衬底温度、氧分压及后处理工艺等因素对氧化锌薄膜结晶性能、表面形貌、择优取向与微结构的影响,并对溅射工艺与取向、结构的关系进行了分析比较,从而确定了最佳溅射及后处理条件并获得了c轴择优取向的ZnO薄膜。     

Negative giant surface potential of vacuum-evaporated tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)3] film

Negative giant surface potential was realized in a vacuum-evaporated film of tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)₃]. Electroabsorption response of the film presented an inverted polarity to that of tris(8-hydroxyquinolinolato) aluminum (Alq₃), suggesting opposite noncentrosymmetry of molecular orientation. Asymmetric dice model with molecular geometric effect has been proposed, and propyl substitution at 7 position of the ligands was indicated to affects the molecular posture on the surface to invert the polarity of noncentrosymmetry. Our results opened a new possibility of controlling molecular orientation in a film for device applications.     

热电Ca3Co4O9薄膜的一致取向生长及其激光感生电压效应

利用脉冲激光沉积(PLD)法,在蓝宝石(0001)平衬底上成功制备了c轴一致取向的Ca3Co4O9薄膜。利用X射线衍射(XRD)分析测定了薄膜的相结构和生长取向。研究了不同衬底温度与不同原位氧压对Ca3Co4O9薄膜结晶质量与生长取向的影响,确定了最佳生长条件。利用这一条件在倾斜Al2O3(0001)衬底上制备了Ca3Co4O9薄膜。研究发现,当Ca3Co4O9薄膜被波长248nm,脉冲宽度20ns的脉冲激光照射时,在薄膜两端存在较大的激光感生热电电压(LITV)信号,峰值电压达到4.4V,其上升沿为36ns,半峰全宽(FWHM)为131ns。可以认为这种激光感生热电电压信号是由于Ca3Co4O9薄膜面内与面间泽贝克(Seebeck)系数张量的各向异性引起的。     

无线Ad-Hoc网络

无线Ad—Hoc网络是由一组自主的无线节点或终端相互合作而形成的、独立于固定基础设施并且采用分布式管理的网络，具有自主性、无严格的控制中心、动态拓扑等特点。路由技术、安全问题和QoS等是目前无线Ad—Hoc网络发展中的关键。尽管无线Ad—Hoc网络具有带宽受限等缺点。由于具备灵活机动、组网迅速的优势．尤其适用于野战军用通信．目前它在民用领域的应用也在逐步扩大。     

一种带权动态调整的总体布线算法及其实现

本文对现有的总体布线方法及宏单元阵列总体布线问题进行了详细分析,提出了一种基于带权动态调整思想的适合于宏单元阵列一层半和双层版图模式的总体布线算法,其目标是合理地利用已确定的布线区域,使各线网均匀地分布在芯片上,获得尽可能高的布通率。