光纤传感技术在覆岩“两带”高度探测中的应用

为准确地掌握工作面采动过程中顶板岩层破规律及其特征,获得相应的技术参数,消除突水威胁、保障煤层安全开采等煤矿防治水工作。运用分布式光纤监测技术可以在其长度范围内连续监测覆岩在开采过程中应力应变的分布及大小,获得煤层覆岩的变形规律。结果表明,这种监测方法的突出优点就是改变了传统的点式监测方式,弥补了点式监测的不足,实现了实时、长距离和分布式的监测目标。该技术在内蒙古某煤矿"两带"高度探测中取得结果和并行电法监测相互验证,证明了该方法的可行性。     

Development of a Ground-Based LIF Instrument for Measuring HOx Radicals: Instrumentation and Calibrations

An instrument for measuringtropospheric OH/HO₂ radicals by laser-inducedfluorescence developed in our laboratory is presentedin detail. It is based on FAGE (fluorescence assay bygas expansion) technique and OH is both excited anddetected at 308 nm corresponding to its A-X(0,0) band.The alignment of the laser beam, the design of thesample gas inlet, and the devices for the fluorescencedetection are optimized so as to reduce the backgroundsignal while keeping the OH sensitivity as high aspossible. A thermalized position of the expanding gasbeam is probed in our system and we did not observe asevere decrease of the HO_x sensitivities under humidconditions. An optical fiber is used for deliveringthe laser light to the fluorescence detection cellmounted outside at a high position. Thus the laserbeam alignment is by far simplified and is made highlyreproducible, once settled properly. For thecalibration, two methods are employed: a system withlaser absorption measurements of OH and a system ofsimultaneous photolysis of H₂O and O₂. Thecalibration factors are compared well within thecombined uncertainty. Using the latter system, theconversion efficiency of HO₂ to OH by NO additionis measured to be around 90%. The detection limitsfor OH and HO₂ (S/N = 2) are estimated to be3.3 × 10⁶ and 3.6 × 10⁶cm^–3 at noon,respectively, with an integration time of 1 min. Theresults of test observations at our institute are alsopresented.     

碳纤维布改善高强混凝土柱延性的试验研究

本文进行了8根高强混凝土柱在低周反复荷载作用下的试验，研究了使用碳纤维布横向包裹的高强混凝土柱来提高其延性这种加固方法的有效性。本文研究了碳纤维布横向包裹高强混凝土柱的受力特性，分析了加荷角度，碳纤维布拉伸强度以及碳纤维布的包裹层数等因素对构件抗震加效果的影响，并对碳纤维布加固高强混凝土柱使其延性提高的机理进行了探讨，试验结果表明，横向缠裹碳纤维布可显著提高高强混凝土柱的延性。     

我国第四纪地质科学应用的新领域——海底光缆工程路由勘察

文章介绍了第四纪地质学的一个新的应用领域--海底光缆工程路由勘察.该项勘察是在全球经济发展,人类从工业化向信息化社会转变,信息化基础建设蓬勃兴起的时代出现并逐步完善的一个新的海洋工程领域.海底光缆建设在国内外得到迅速发展.我国修建的国内外海底光缆已达20余条.海底光缆工程路由勘察与第四纪地质学关系密切.海洋第四纪地质现象是它进行勘察和研究的主要内容.海底光缆路由勘察使用先进的仪器设备,采集的是数字化信息,能快速准确的成图.该图反映路由区海底所有的自然环境特征.勘察融汇了现代化的高新技术,拓宽了第四纪研究的领域,推动了第四纪地质学的发展.     

棉纤维生长各阶段的土壤水分状况对其束强的影响

在纤维伸长前期、填充后期充足的土壤水分对提高束强有利，纤维生长扭曲期土壤干旱对提高束强有利，反之则不利。     

反复荷载下碳纤维布加固钢筋混凝土框架梁的试验研究

通过2个碳纤维布加固钢筋混凝土框架梁和1个未加固框架梁的对比试验，分析了低周反复荷载作用下碳纤维布加固框架梁的加固效果，提出了加固梁的正截面承载力计算方法。     

Seismic performance of laminated timber frames with fiber‐reinforced joints

A series of dynamic experiments was performed on two‐story glue‐laminated timber frames. The tests included sinusoidal sweeps in one direction, arbitrary signals simulating earthquake loads in two directions, and harmonic free vibration at the fundamental frequency. Two experimental frames were manufactured and tested: (1) a control with horizontal laminations and no reinforcement at joint areas, and (2) a new frame design with densified material in the joint area that was further reinforced by glass‐fiber composite material. Preliminary tests of scaled and full‐size beam‐to‐column connections were performed to obtain connection characteristics needed for subsequent analytical modeling. Copyright © 2004 John Wiley & Sons, Ltd.     

Analysis of tubular steel bridge piers

A one‐dimensional model is proposed for the static and dynamic analysis of tubular steel bridge piers subjected to strong ground motions. The present formulation does not require experimental results nor shell analysis to obtain the constitutive equation of the model, which shows strength deterioration. The material properties and dimensions of bridge piers are required for static and dynamic analysis of the present model. The present analysis consists of two steps. The first step is to obtain the stress and strain relationship of the base plastic‐hinge region, where local inelastic buckling is observed. The modified Shanley's model and fiber elements are used to establish the compressive skeleton curve. The strength deterioration is taken into account in the resulting constitutive model. The second step is to analyze static and dynamic responses of tubular steel bridge piers. For overall analysis, the base plastic‐hinge region is discretized in the circumferential direction by using fiber elements whose constitutive equation was obtained in the first step. The validity of the present model has been confirmed through comparisons with existing experimental results. Copyright © 2005 John Wiley & Sons, Ltd.     

International Competition Between Satellite and Fiber Optic Carriers: A Geographic Perspective*

International telecommunications traffic relies entirely on two modes of transmission, satellites and fiber optics, which exhibit considerable but not complete fungibility. This article explores the economic and geographic dimensions of these two industries in the context of the growing market in global data and telephony traffic. First, it summarizes the changing conditions that have accentuated competition between them, including deregulation, technological change, and globalization. Next, it examines the changing cost structures, transmission capacities, and traffic volumes for each technology in the critical transatlantic and transpacific markets. Throughout, it documents the steady encroachment by fiber optics firms that threatens the viability of commercial satellite operators, a challenge the latter hope to meet though the growth of the cellular telephone market.     

结晶膜蒸馏处理吸收炼矿烟气酸性废水的研究

采用天然碳酸钙中和烟气吸收酸性废水,研究中空纤维结晶膜蒸馏技术对中和后废水处理的效果。考察了料液温度、起始浓度、流速、pH值等因素对膜通量的影响。在选定的条件下对水样进行连续膜蒸馏处理。结果表明,在料液温度50℃,料液速度为18.5mL/min,pH值为7,运行18h后,浓缩溶液开始出现结晶,结晶效果较好。截留率均接近100%。