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木材横纹压缩应力-应变关系及其影响因素研究进展

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林产工业 2018年第11期45卷 11-16页

作者：伍艳梅黄荣凤高志强王艳伟李任中国林业科学研究院木材工业研究所 Jiusheng Flooring corporation

木材横向压缩下应力-应变关系对压缩材料热压工艺的设计和最终产品的物理力学性能有着重要的影响。从木材横纹压缩应力-应变关系和屈服点的确定入手,重点阐述从微观到宏观角度的木材自身组织构造特性,以及压缩工艺参数中温度、含水率等... 详细信息

木材横向压缩下应力-应变关系对压缩材料热压工艺的设计和最终产品的物理力学性能有着重要的影响。从木材横纹压缩应力-应变关系和屈服点的确定入手,重点阐述从微观到宏观角度的木材自身组织构造特性,以及压缩工艺参数中温度、含水率等因素对木材横纹压缩应力-应变关系的影响,并对今后木材横纹压缩技术研究方向提出了建议。目前木材横纹压缩变形机制的研究多是围绕木材整体压缩开展,缺乏木材应力-应变关系随木材自身特性及含水率、温度交互作用变化规律的系统研究,以及湿热状态下层状压缩木材内部屈服应力差形成机制的研究。要实现层状压缩木材压缩层位置和厚度的可控性,需要在准确确定木材屈服点和掌握木材应力-应变关系的湿热响应规律的前提下,科学构建适用于湿热条件下木材层状压缩应力-应变关系模型。

关键词：横纹压缩应力-应变关系层状压缩屈服点屈服应力

Effect of off-zenith observations on reducing the impact of precipitation on ground-based microwave radiometer measurement accuracy

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Effect of off-zenith observations on reducing the impact of ...

MORPHOLOGY And MECHANICAL PROPERTIES OF HIGH PERFORMANCE NYLON-6 COMPOSITES REINFORCED BY MULTIWALLED CARBON NANOTUBES

第31届中国气象学会年会

作者： Guirong Xu Randolph (Stick) Ware Wengang Zhang Guangliu Feng Kewen Liao Yibing Liu Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research Institute of Heavy Rain China Meteorological Administration Radiometrics 4909 Nautilus Court North Boulder CO USA Wuhan Meteorological Bureau of Hubei Province

Microwave radiometers(MWR) can be useful for the detection of mesoscale phenomena because they provide thermodynamic profiles in a minute time scale. These profiles are mainly used in non-precipitation conditions due to degraded accuracy of the MWR measurements in precipitation. Recently, Radiometrics corporation used proprietary neural network methods to retrieve temperature, humidity and liquid profiles from off-zenith(15° elevation) radiometer observations to provide higher accuracy during precipitation. In this paper, using the MWR-retrieved temperature and humidity profiles with collocated radiosondes from June 2010 to September 2013 in Wuhan, the impact of precipitation on the MWR measurement accuracy as well as the effect of off-zenith neural network methods on it is investigated. In precipitation, the correlation coefficients of the MWR temperature and vapour density profiles against radiosondes are smaller than that in non-precipitation, and the bias and RMS against radiosondes also increase, especially around 2 km heights. For the MWR relative humidity profile, the correlation coefficient in precipitation is obvious smaller than that in non-precipitation below 4.5 km, and the bias and RMS against radiosondes are clearly larger above 5.5 km. Moreover, the differences between the precipitation and non-precipitation cases mostly are statistically significant. Compared with the results of the zenith observation, the off-zenith observation makes a positive effect on reducing the impact of precipitation on the accuracy of MWR temperature and vapour density retrievals. On the whole, the MWR temperature bias and RMS against radiosondes in precipitation are reduced from 3.6 and 4.2 K to 1.3 and 3.1 K, respectively, and the MWR vapour density bias is also reduced from 1.10 g/m3 to 0.18 g/m3 with the RMS decreasing from 2.90 g/m3 to 1.91 g/m3. The temperature correlation coefficient between the MWR and radiosonde in precipitation is clearly improved above 3 km height

关键词： microwave radiometer off-zenith observation precipitation accuracy

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MORPHOLOGY AND MECHANICAL PROPERTIES OF HIGH PERFORMANCE NYL...

高速公路环境下北斗+5G高精度定位服务性能评估（英文）

Asia Conference on Nanoscience and Nanotechnology Abstracts Book

作者： IN YEE PHANG SHUE YIN CHOW institute of Materials Research and Engineering Singapore 117602Republic of Singapore institute of Materials Research and Engineering Singapore 117602Republic of Singapore

＜正＞ Since the discovery of carbon nanotubes （CNTs） by Iijima in 1991, increasing attention has been attracted to this newly emerging material due to its remarkable mechanical and electrical properties. Based on their unique and excellent physical properties, many structural and smart applications of CNTs have been proposed including transistors, sensors, and field emission devices, as well as lighter, smaller and higher performance structures for aerospace and many other industrial fields. Among them, one of the most intriguing applications of CNTs is the polymer/CNTs nanocomposites. However, the challenges for developing high performance CNTs/polymer composites are: （i） homogeneous dispersion of CNTs in the matrix, and （ii） strong interfacial interactions so as to effect efficient load transfer from the polymer matrix to the CNTs.

关键词： Carbon nanotubes composites mechanical properties.

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aerospace china 2024年第2期 15-20页

作者： LI Qi ZHU Peilin DING Zhenke Beijing Research institute of Telemetry Zhejiang Highway & Water Transportation Engineering Consulting corporation Beijing University of Posts and Telecommunications

With the rapid development of intelligent connected vehicles, high-precision 3D navigation has become a key supporting technology. This article conducted a series of drive tests using the high-precision navigation technology of BeiDou and BeiDou+5G hybrid positioning technology, aiming to verify the positioning performance in complex highway traffic environments. The test was conducted on actual roads in Beijing and Hangzhou showed that the positioning accuracy of BeiDou high-precision navigation reached a real-time centimeter level, with a fixed rate of about 95% and a convergence time of less than 2 s. The elevation accuracy of BeiDou+5G hybrid positioning was better than 0.2 m. Combined with three-dimensional high-precision laser point cloud maps, the overlay verification showed that the model can support three-dimensional lane level navigation, verifying the application potential of BeiDou high-precision positioning and BeiDou+5G hybrid positioning technology in the fields of autonomous driving and intelligent connected vehicles.

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Russia and china Signed a Statement on a Joint GNSS Monitoring and Assessment Service

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aerospace china 2017年第3期18卷 63-63页

作者： GUO Qian LIU Yingwen china Space News

At the recent, 4th meeting of the Chinese-Russian Committee on Impor- tant Projects of Strategic Cooperation in the field of Satellite Navigation held in St. Petersburg, Russia. The china academy of aerospace Electronics technology and FSUE TsNIIMASS, the main research institute of Roscosmos State corporation signed a statement on a new joint GNSS monitoring and assessment service.

关键词： Russia china GNSS

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轮轨垂向力地面连续测量的复合测区方法

中国铁道科学 2019年第5期40卷 87-94页

作者：李旭伟曾宇清李甫永田光荣秦菊中国铁道科学研究院集团有限公司铁道建筑研究所北京100081 Transportation technology Center Inc.Pueblo CO USA 81001 中国铁道科学研究院集团有限公司机车车辆研究所北京100081

对既有广泛运用的“剪力+支撑力”轮轨垂向力测量方法进行分析,表明在共用剪力传感器位置存在长度约1个钢轨高度的剪力测量过渡(无效)区,导致测量结果不能真实反映左右侧钢轨间剪力的大小;为此提出轮轨垂向力地面全连续测量的复合测区方... 详细信息

对既有广泛运用的“剪力+支撑力”轮轨垂向力测量方法进行分析,表明在共用剪力传感器位置存在长度约1个钢轨高度的剪力测量过渡(无效)区,导致测量结果不能真实反映左右侧钢轨间剪力的大小;为此提出轮轨垂向力地面全连续测量的复合测区方法,在不改变“剪力+支撑力”轮轨垂向力测量方法连续单元测区布置的同时,通过增加约束条件、构建复合测区,提取各连续单元测区与相邻连续单元组成的复合测区有效轮轨垂向力,并按照时序进行组合,实现在不增加硬件条件下完成轮轨垂向力的地面长距离全连续测量。基于铁路车辆运行状态地面安全监测系统(TPDS)实测数据,进行复合测区方法的具体实施,并与仿真结果对比,验证该方法对轮轨垂向力全连续测量的有效性。将该方法应用在TPDS中,拓展其功能,结果表明:复合测区方法的应用,能实现车轮多边形和辋裂的监测,为安全监测、评估提供有效手段。

关键词：轮轨垂向力连续测量 TPDS 车轮多边形辋裂

高分辨率定量遥感的偏振光效应与偏振遥感新领域

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遥感学报 2018年第6期22卷 901-916页

作者：晏磊顾行发褚君浩尤政刘世元 Hugh Motimor V.Chandrasekar 北京大学地球与空间科学学院遥感与地理信息系统研究所、空间信息集成与3S工程应用北京市重点实验室北京100871 中国科学院遥感与数字地球研究所北京100101 中国科学院上海技术物理研究所上海200083 清华大学精密仪器系北京100084 华中科技大学数字制造装备与技术国家重点实验室武汉430074 Rutherford Appleton Laboratory Space Science and Technologies Facilities Counci Colorado State University Fort CollinsColorado 80523

随着航空航天高分辨率观测手段的逐步成熟,定量遥感在有效解决了光学地表多尺度效应后,更高分辨率的光学偏振效应在地表、大气、仪器3大要素方面逐步全面凸显出来,并直接决定或影响高分辨率观测系统的定量遥感效能实现和质量保障。例如... 详细信息

随着航空航天高分辨率观测手段的逐步成熟,定量遥感在有效解决了光学地表多尺度效应后,更高分辨率的光学偏振效应在地表、大气、仪器3大要素方面逐步全面凸显出来,并直接决定或影响高分辨率观测系统的定量遥感效能实现和质量保障。例如,植被冠层极其微弱的多次散射反射偏振效应,如果不加扣除其模型误差达到136%;大气衰减本质是大气偏振效应,是遥感反演的最大误差源,误差达到5%—30%,偏振手段扣除大气误差目前已可以降低一半以上的误差;观测仪器扣除多次散射透射偏振光后,可以实现5 nm分辨率下0.1—0.3 nm高光谱定标能力,并借助偏振强化光噪声分离出中心波长偏移和带宽退化的误差根源。借助偏振"强光弱化,弱光强化",能够实现稳定度达10^(-8)月球辐亮度基准观测,为遥感辐亮度定标不确定度由7%到1%—2%跨越提供可能。

关键词：高分辨率定量遥感偏振光效应地表偏振效应大气偏振效应仪器偏振效应偏振遥感

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通用分组网络寻址路由与标识演进方法及系统

中国科学：信息科学 2023年第8期53卷 1629-1644页

作者：李挥邬江兴韦国华孟详帧白鹤林立宏杨昕伊鹏宗泽斌魏进武朱伏生陆以勤缪伟豪杨伟豪郑泽峰马军锋张明龙张汉裕褚晓理何品翰王泽华北京大学深圳研究生院深圳518055 国家数字交换系统工程技术研究中心郑州450002 鹏城实验室深圳518055 中国电信股份有限公司北京100033 中国联合网络通信有限公司北京100032 广东省新一代通信与网络创新研究院广州510289 华南理工大学电子与信息学院广州510006 香港科技大学电子与计算机工程系中国香港香港中文大学信息工程系中国香港澳门科技大学资讯科技学院中国澳门中国信息通信研究院北京100191 Department of Electrical and Electronic Engineering Auckland University of TechnologyAuckland 1142NewZealand Department of Electronic and Electrical Engineering The University of SheffieldSheffield S102TNUK Department of Electrical and Computer Engineering University of WaterlooWaterloo N2L 3G1Canada Department of Electrical and Computer Engineering The University of British ColumbiaVancouver V6T 1Z2Canada

未来的网络通信需求动态多样,网络层功能也应适时而变,因此对网络可演进性的研究具有重要意义.多标识网络作为一种兼容性极强的网络架构,网络层功能十分丰富,但仍缺少网络演进性设计.本文为多标识网络设计了一种通过标识扩展来支持网络... 详细信息

未来的网络通信需求动态多样,网络层功能也应适时而变,因此对网络可演进性的研究具有重要意义.多标识网络作为一种兼容性极强的网络架构,网络层功能十分丰富,但仍缺少网络演进性设计.本文为多标识网络设计了一种通过标识扩展来支持网络体系不断演进的方案,包括对标识空间进行形式化定义,设计标识回退候选标识的优先级排序算法以及设计支持标识扩展的路由转发协议;并且在ndnSIM网络仿真环境和多标识网络测试床中实现了上述方案,评估了标识扩展方案的可行性和性能.实验结果表明相比于标识扩展机制给网络架构带来的益处,其性能损失在可接受的范围内.

关键词：多标识网络标识扩展网络演进原型系统 ndnSIM仿真