等通道转角挤压自增强等规聚丙烯研究

为了研究等通道转角挤压等规聚丙烯的挤压工艺条件、结构与性能之间的关系,采用90°转角模具及挤压路径A、在熔点以下的160℃制备了不同挤压次数的等规聚丙烯样品,利用广角X射线衍射(WAXD)、差示扫描量热分析(DSC)等手段对其结构进行表征.结果表明,随挤压次数增加,等规聚丙烯分子取向明显增加,材料结晶度提高,试样的力学性能提高十分显著,未挤压试样的抗拉强度为17.13 MPa,经过三次挤压后,抗拉强度提高到59.38 MPa.     

电力线通信(PLC)技术综述

论述了电力线通信技术概况、技术分类、功能定位、主要用途、网络体系结构特征、发展动态、标准化进展、EMC问题等，侧重于宏观分析，不涉及技术细节。     

基于电磁感应的钢筋定位及埋深检测新方法研究

钢筋混凝土结构广泛运用于电力基础设施中,对其内部钢筋参数进行检测能够有效判断其结构耐久性,对保障电力系统安全稳定运行有重要的意义。针对传统钢筋混凝土检测方法无法判断混凝土内钢筋走向及埋深测量不够精确的问题,通过对钢筋测量原理分析和霍尔传感器布局设计,提出了一种基于电磁感应的钢筋定位及埋深检测方法。该方法用于判断钢筋的中心位置并测量其偏转角度,同时利用拟合得到的函数反应检测值与钢筋埋深之间的关系。实验表明,埋深检测值受到相邻钢筋的影响而存在较大误差,间距越小误差越大,因此通过BP（Back propagation）神经网络对不同间距下的检测值进行了数据修正,有效地提高了混凝土中钢筋埋深的检测精度。     

厚度方向性能Q345EZ35中厚板的开发

介绍了厚度方向性能Q345EZ35中厚板开发的主要技术和关键环节,该中厚板的实物质量符合国家标准要求。     

The effect of roll-processing orientation on stress corrosion cracking of warm-rolled 304L stainless steel in oxygenated and deoxygenated high temperature pure water

Stress corrosion crack growth rates of 304L stainless steel after one-directionally warm-rolled along the longitudinal (L) direction were measured in oxygenated and deoxygenated pure water at 288 °C. The fracture mode is mainly intergranular in the Transverse-longitudinal (T-L) orientation specimen, while it is occasionally intergranular in the Longitudinal-transverse (L-T) orientation specimen. The crack growth rates in the T-L orientation are higher than those in the L-T orientation in both oxygenated and deoxygenated environments, which is related to the effective cracking growth path as the result of microstructural anisotropy and applied loading direction.     

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…