螺旋埋弧焊管预精焊生产线导电刷结构改进

在螺旋埋弧焊管预精焊焊接过程中,导电刷与钢管表面接触是否良好,直接影响钢管埋弧焊缝及管体表面质量。通过增强导电刷底板强度,增加导电刷数量,优化导电刷角度调节及固定结构等,解决了焊接过程中由于导电刷与钢管表面接触不良产生的焊缝缺陷及钢管表面电弧烧伤问题,提高了焊接质量,减少了导电刷更换频次及使用数量,节约了材耗,实现了改进的目的。     

基于ICE与HTTP Tunnel技术的NAT/FW穿越方案

在现代网络中,越来越多的主机被部署在NAT和防火墙(FW)之后,这就要求VoIP、P2P等通信软件必须具备穿越NAT/FW的能力,才能实现端到端的数据传输.现有的STUN、TURN、ICE等方案虽然可以穿越大部分NAT/FW,但对有端口或协议限制的防火墙却无能为力.本文提出了将ICE和HTTP Tunnel技术相结合的穿越方案,设计并实现了可跨平台运行的HTTP Tunnel模块来配合ICE进行穿越.实验证明,在防火墙只开放80端口这种苛刻的条件下,该HTTP Tunnel模块也能够成功穿越大部分防火墙,实现数据流的稳定传输.     

Polydimethylsioxane fluidic interconnects for microfluidic systems

This paper presents novel polydimethylsioxane (PDMS) based interconnects for microfluidic systems with a low dead volume. Through-hole type and "/spl lceil/" type PDMS interconnects have been designed, fabricated, and tested for glass and plastic capillary tubing. Oxygen reactive ion etching and epoxy bonding methods are employed to bond PDMS interconnects to different substrate materials including silicon, glass, polymer and other thin film materials. Leakage pressure, leakage rate, and pull-out force are characterized for these interconnects. For reusable PDMS interconnects, the maximum leakage pressure reaches 510 kPa (75 psi) and the maximum pull-out force is about 800 mN. For nonreusable PDMS interconnects, the maximum leakage pressure is found to be 683 kPa (100 psi) and the maximum pull-out force is 2 N. For both types of PDMS interconnects, the leakage rate test demonstrates that the leakage is not detectable at a working pressure of 137 kPa (20 psi).     

聚乙烯催化剂表面分形和多重分形特征

应用分形和多重分形理论研究了负载型聚乙烯催化剂(简称催化剂)表面形态。提出一种图片处理和计算过程更加完备的基于扫描电子显微镜照片的分形维数和多重分形谱计算程序,对4种催化剂进行分析计算。探讨了分形维数、多重分形谱相关参数与催化剂表面形态及与聚合活性的对应关系。实验结果表明,催化剂表面形态的复杂程度可以用表面分形维数来表征,聚合活性高的催化剂表面形态更加复杂,有更大的比表面积,对应的分形维数值也越大。催化剂表面分形维数的变化程度可以用多重分形谱来表征,聚合活性高的催化剂表面分形维数的跨度和分散程度更高。提出的分形维数和多重分形谱计算程序为催化剂的评定与设计提供了一种实用的手段。     

陆地移动卫星通信系统设计中的多径衰落研究

分析和讨论了陆地移动卫星系统设计中的多径误落分布，根据Ｎａｋａｇａｍｉ－Ｒｉｃｅ分布和实验数据提出了ＬＭＳＡ中的多径衰落预测新方法。经比较，该方法预测值同数据吻合较好且有合理的物理解释和较大的适用范围。     

地物介电常数测量和分析

详细分析了基于矢量风络分析仪的同轴线探头介电常数测量系统和地物介电常数的测量方法。给出了几种典型地物（沙子、岩石、树木、棉叶）介电常数的测量和分析结果，并在模型进行了比较。本文实测数据可用于地物散射和辐射特性研究。     

Achieving High‐Performance Nondoped OLEDs with Extremely Small Efficiency Roll‐Off by Combining Aggregation‐Induced Emission and Thermally Activated Delayed Fluorescence

Luminescent materials with thermally activated delayed fluorescence (TADF) can harvest singlet and triplet excitons to afford high electroluminescence (EL) efficiencies for organic light‐emitting diodes (OLEDs). However, TADF emitters generally have to be dispersed into host matrices to suppress emission quenching and/or exciton annihilation, and most doped OLEDs of TADF emitters encounter a thorny problem of swift efficiency roll‐off as luminance increases. To address this issue, in this study, a new tailor‐made luminogen (dibenzothiophene‐benzoyl‐9,9‐dimethyl‐9,10‐dihydroacridine, DBT‐BZ‐DMAC) with an unsymmetrical structure is synthesized and investigated by crystallography, theoretical calculation, spectroscopies, etc. It shows aggregation‐induced emission, prominent TADF, and interesting mechanoluminescence property. Doped OLEDs of DBT‐BZ‐DMAC show high peak current and external quantum efficiencies of up to 51.7 cd A^?1 and 17.9%, respectively, but the efficiency roll‐off is large at high luminance. High‐performance nondoped OLED is also achieved with neat film of DBT‐BZ‐DMAC, providing excellent maxima EL efficiencies of 43.3 cd A^?1 and 14.2%, negligible current efficiency roll‐off of 0.46%, and external quantum efficiency roll‐off approaching null from peak values to those at 1000 cd m^?2. To the best of the authors' knowledge, this is one of the most efficient nondoped TADF OLEDs with small efficiency roll‐off reported so far.     

2000-2019年新疆水-能源-粮食系统耦合协调发展研究

水、能源和粮食是区域可持续发展的关键要素。以新疆维吾尔自治区为研究区,构建水-能源-粮食(W-E-F)系统综合评价指标体系,利用耦合协调度模型和灰色GM(1,1)模型,分析新疆2000-2019年W-E-F系统耦合协调发展水平,并对2020-2031年的耦合协调度进行预测。结果表明：2000-2019年新疆W-E-F系统的综合评价指数由0.39增大至0.61,整体上呈现上升趋势;耦合协调度从0.59增大至0.77,3个子系统之间存在着密切的联系,目前整体表现为中级协调发展水平,并预测在2025年将过渡为高级协调发展阶段。水资源子系统仍是制约W-E-F系统协调发展的关键,农业用水占比过大,导致新疆总体上结构型缺水严重。未来应积极调整用水结构,提高水资源利用效率,优化粮食消费结构,以提升系统内部的协调性。     

阶梯栅氧结构的NLDMOS热载流子效应研究

本文对一种新型的阶梯栅氧结构的NLDMOS（Step Gate Oxide NLDMOS , SG-NLDMOS）的热载流子效应进行了研究。采用直流电压应力实验、TCAD仿真、电荷泵测试等方法,对退化现象进行了分析,并提出了退化机制。然后研究了漂移区注入剂量对器件热载流子效应的影响,结果表明低的漂移区注入剂量可以更有效地减小器件导通电阻的退化。     

多波段多极化海杂波特性的实验研究

长期以来,海杂波特性研究一直是雷达和微波遥感界普遍关心的问题。本文讨论基于矢量网络分析仪组建的波谱计对海杂波特性所进行的多波段(S,C,X,Ku)多极化测量,包括测量系统、实验描述和数据处理方法,通过数据分析得到不同海态下杂波特性(散射系数、多普勒谱等)随频率、极化和人射角(含小擦地角)的变化关系并给出一些典型结果。