建筑结构胶粘剂的发展和展望

建筑结构胶粘剂经过30多年的发展已成为重要的结构粘接材料。本文综述了建筑结构胶粘剂发展与技术进步。并针对研发、原材料、生产及标准中存在的问题,探讨了其发展方向。     

一种可用于高盐废水处理的纳滤膜研究

使用三乙烯四胺（TETA）和2,3-环氧丙基三甲基氯化铵（EPTAC）混合溶液为水相单体,均苯三甲酰氯（TMC）为油相单体,通过界面聚合制备纳滤膜。结果表明在水相溶液中TETA浓度为0.2 wt%,EPTAC浓度为0.4 wt%,油相溶液 TMC 为 0.2 wt%,反应时间 30 s,在 90 ℃下热处理为最佳条件。该复合膜在 25 ℃、0.5 MPa 条件下纯水通量为80 L/（m²·h）,是未添加 EPTAC 时水通量的 5.5 倍,对 NaCl 和 Na₂SO₄的截留率分别为 15% 和 98%;对于 15 000 mg/L NaCl 和 8 000 mg/L Na₂SO₄混盐溶液体系,Cl^-截留率低于 1%,SO₄^2-截留率高于 99.2%,显示了高分离选择性,满足高盐废水分盐要求。抗污染实验结果表明,该膜具有较好的抗污染性能,水通量恢复率可达99%。     

停车场远程视频监控系统的设计与开发

提出和实现了一种基于嵌入式设备的停车场视频监控和车位检测方案。在嵌入式Linux操作系统下,通过调用计算机视觉库OpenCV中的图像处理函数,实现多车位的检测,检测结果保存到嵌入式数据库中。通过嵌入式设备将车位信息发送给PC或手持设备,并以图像的形式显示,达到远程车位检测的目的。本系统还移植了Mjpgstreamer实现停车场的远程视频监控。车位状态的检测采用2种判据:一是车位范围内差影的均值;二是车位区域内的边缘点数。测试结果表明,该方案可以很好地运行在嵌入式平台,为停车诱导提供支持。     

统计视角下动物源性食品安全监管问题及对策

<正>当前动物源性食品安全监管现状随着社会和经济水平的不断发展,人们的生活质量也逐步提升,对于生活水平的要求也变得越来越高,动物源性食品已经成为食品种比重较高的一个类型。所谓的动物源性食品,其实就是指的是生活中一切可供食用的动物组织、奶类以及蛋等,涵盖动物的肉类以及相关的制品等。这些动物源性食品为人们提供了丰富的蛋白质、维生素、脂肪以及各种营养物质和微量元素。发展到现在,动物性视食品已经成为人类生活中不可或缺的物质需求。随着社会经济水平的不断提高,动物源性食品使人们的饮食结构产生了非常大的变化。     

Influence of growth conditions on the V-defects in InGaN/GaN MQWs

The influence of the growth temperature,TMIn/TEGa andⅤ/Ⅲratio on the V-defects of InGaN/GaN multi-quantum wells（MQWs） has been investigated and discussed.When the TMIn flow increases from 180 to 200 sccm,the density of V-defects increases from 2.72×10¹⁸ to 5.24×10¹⁸ cm^-2,and the V-defect width and depth increase too.The density also increases with the growth temperature.The densities are 2.05×10⁸,2.72×10¹⁸ and 4.23×10⁸ cm^-2,corresponding to a growth temperature of 748,753 and 758℃respectively.When the NH₃ flows are 5000,6600 and 8000 sccm,the densities of the V-defects of these samples are 6.34×10¹⁸,2.72×10¹⁸ and 4.13×10¹⁸ cm^-2,respectively.A properⅤ/Ⅲratio is needed to achieve step flow growth mode.We get the best quality of InGaN/GaN MQWs at a growth temperature of 753℃TMIn flow at 180 sccm,NH₃ flow at 6600 sccm,a flatter surface and less V-defects density.The depths of these V-defects are from 10 to 30 nm,and the widths are from 100 to 200 nm.In order to suppress the influence of V-defects on reverse current and electro-static discharge of LEDs,it is essential to grow thicker p-GaN to fill the V-defects.     

插入n-AlGaN/GaN超晶格改善GaN基LED的droop效应

在GaN基LED的n-GaN和InGaN/GaN发光区之间插入n-AlGaN/GaN超晶格来改善其droop效应。注入电流低于100mA时,插入n-AlGaN/GaN超晶格的LED的流明效率低于没有插入层的LED。注入电流高于100mA时,插入n-AlGaN/GaN超晶格的LED的流明效率高于没有插入层的LED。插入n-AlGaN/GaN超晶格后,GaN基LED在-5V的反向电压下,漏电由2.568029μA减少到0.070543μA。人体模式下,插入n-AlGaN/GaN超晶格的LED在2000V的静电电压下的通过率从60%提高到了90%。LED droop效应的改善是因为n-AlGaN/GaN超晶格过滤了穿透位错并改善了电流扩展能力。     

Improvement of the efficiency droop of GaN-LEDs using an AlGaN/GaN superlattice insertion layer

With an n-AlGaN(4 nm)/GaN(4 nm) superlattice(SL) inserted between an n-GaN and an InGaN/GaN multiquantum well active layer,the efficiency droop of GaN-based LEDs has been improved.When the injection current is lower than 100 mA,the lumen efficiency of the LED with an n-AlGaN/GaN SL is relatively small compared to that without an n-AlGaN/GaN SL.However,as the injection current increases more than 100 mA,the lumen efficiency of the LED with an n-AlGaN/GaN SL surpasses that of an LED without an n-AlGaN/GaN SL. The wall plug efficiency of an LED has the same trend as lumen efficiency.The improvement of the efficiency droop of LEDs with n-AlGaN/GaN SLs can be attributed to a decrease in electron leakage due to the enhanced current spreading ability and electron blocking effect at high current densities.The reverse current of LEDs at -5 V reverse voltage decreases from 0.2568029 to 0.0070543μA,and the electro-static discharge(ESD) pass yield of an LED at human body mode(HBM)-ESD impulses of 2000 V increases from 60%to 90%.     

P 型氮化镓层生长压力对InGaN/GaN基发光二极管性能的影响

The advantages of In Ga N/Ga N light emitting diodes(LEDs) with p-Ga N grown under high pressures are studied.It is shown that the high growth pressure could lead to better electronic properties of p-Ga N layers due to the eliminated compensation effect.The contact resistivity of p-Ga N layers are decreased due to the reduced donor-like defects on the p-Ga N surface.The leakage current is also reduced,which may be induced by the better filling of V-defects with p-Ga N layers grown under high pressures.The LED efficiency thus could be enhanced with high pressure grown p-Ga N layers.