用于桥梁结构挠度自动监测的新型传感技术

挠度是评价桥梁安全性和开展桥梁监测的重要指标.分析了用于桥梁结构挠度自动监测各种新型传感技术的基本原理、性能特点及应用范围,并对比这些传感技术的测量精度、测量方式和适用桥型等.结果表明,长期在线自动动态测量和大量程测量是未来桥梁结构挠度自动监测的发展方向.     

中小型桥梁广域健康监测系统的研究

我国是桥梁大国,由于结构老化、运营管理以及建设质量等问题,近年来全国各地相继出现桥梁垮塌事故,造成了严重的人员伤亡和巨大的财产损失。为了保证既有桥梁的安全运营和尽可能延长其安全使用年限,对既有桥梁进行实时健康监测是非常必要的。由于桥梁健康监测系统投资、运营费用巨大和监测技术的不成熟,除少数特大型桥梁安装了监测系统9,9%以上的大、中、小跨径的桥梁都处于监测系统覆盖的盲区。文章主要探讨中小型桥梁健康监测系统的现状及近年来的进展,提出了一种基于智能传感器的中小型桥梁广域健康监测系统结构。     

光纤Bragg光栅传感技术在桥梁预应力监测中的应用研究

针对桥梁预应力检测的问题,提出了采用光纤Bragg光栅(FBG)传感技术进行监测的新方案,分析了光纤Bragg光栅传感器的传感原理,进行了室内、工程现场与常规的电测技术的对比试验.结果表明:光纤Bragg光栅传感器比电检测系统传感器具有更高精度,能绝对数值测量,抗干扰能力强,结构简单,长期稳定性高,实现对工程结构的实时、在线监测.该技术在土木工程界具有广泛的应用前景.     

光纤光栅传感技术在特大跨桥梁施工监测中的应用

本文在光纤Bragg光栅理论研究基础上,结合理论计算,着重对光纤传感技术在特大跨桥梁施工监测中的应用进行了系统的研究,论证了光纤光栅用于大型桥梁施工监测的优越性,具有广阔的应用前景.     

CFRP加固初始损伤桥梁构件性能监测试验研究

由于使用过程中的汽车超载作用和环境侵蚀作用导致既有钢筋混凝土桥梁不可避免地发生损伤,引起变形过大和承载力下降从而影响其使用性能,必须采取维修加固措施方可继续服役.本文通过静载试验模拟汽车超载作用,通过恒电流加速锈蚀试验模拟氯盐侵蚀环境下混凝土构件承载力退化,采用CFRP对存在初始损伤的桥梁构件进行了加固,并采用分布式光纤传感技术(BOTDA)监测了构件内部应变,对比分析了加固前后的挠度、裂缝及应变变化情况.试验结果表明,不同的初始损伤对碳纤维加固效果影响不同,引起较大残余变形的超载损伤对加固后桥梁构件的协同工作能力有明显的降低影响.构件内布设传感光纤在超载状况和钢筋锈蚀情况下均可保证稳定、可靠的性能监测,可用于智能桥梁的设计实施和既有桥梁的实时监测.     

PPP-BOTDA分布式光纤传感技术在水工结构物健康监测中的可行性探讨

基于脉冲预泵浦(pulse-prepump,PPP)布里渊光时域分析的PPP-BOTDA分布式光纤传感技术,作为新近发展起来的一种监测手段,在空间分辨率和精度方面具有明显优势。针对水工结构物健康监测的领域特点,通过多组试验,分析了PPPBOTDA分布式光纤传感技术的平均化次数、重复性、扫频范围、扫频步长、监测时间、长短距离空间定位精度、空间分辨率和采样间隔等各项性能指标,在此基础上,进行了基于该技术的水工结构物温度和应变监测试验,验证了该技术在水工结构物健康监测中的感知性能和可行性。     

基于监测数据的桥梁结构可靠性评估

桥梁结构健康监测系统能有效监测影响桥梁结构的各种作用及其在结构上产生的效应,可为准确评估桥梁结构的各种性能提供信息.影响桥梁结构性能的因素具有随机性,基于概率的方法是处理随机性的有效工具.研究了结构健康监测与可靠性评估相结合的桥梁结构性能评估方法.分析了纵向应变监测信号的特点,提出一种新的监测信息处理方法.结合工程实例,验证了该方法的可行性,并对可靠性评估结果进行分析.     

光纤传感网络在桥梁施工应力监测中的应用

随着桥梁结构施工技术发展和桥跨的不断增长,为确保其施工的质量和安全性,在桥梁建设中对其应力进行实时的监测显得尤为重要.而传统的传感器在恶劣的施工环境中成活率极低,受环境影响较大,具有精度低等缺点.在新建桥梁的应力监测中采用光纤光栅传感技术,然后在有限元模拟的基础上,监测数据与普通传感器所测数据进行比较.结果表明:光纤光栅传感器在桥梁应力监测中具有可行性,为以后桥梁的应力应变监测提供了新方法.     

对桥梁健康监测系统理论的研究

桥梁设计理论的验证以及对桥梁结构和结构环境未知问题的调查与研究扩充了桥梁健康监测的内涵。本文结合近十年来桥梁健康监测的研究状况以及大跨度桥梁工程的研究与发展，较系统地阐述桥梁健康监测的内涵。     

桥梁振动远程监测系统的研究

桥梁振动监测是桥梁健康监测的重要内容,桥梁的振动状态是反映桥梁健康状况的重要参数。本文采用先进的传感监测技术和远程通信技术,开发了基于虚拟仪器的桥梁振动远程监测与预报系统,为桥梁结构健康监测系统的进一步发展应用提供更加丰富的理论成果。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。