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Developed Techniques (developed + techniques)
Selected AbstractsHealth Monitoring of Rehabilitated Concrete Bridges Using Distributed Optical Fiber SensingCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2006Wei Zhang As newly developed techniques, distributed optical fiber sensing (DOFS) have gradually played a prominent role in structural health monitoring for the last decade. This article focuses on the employment of two types of DOFS, namely fiber Bragg grating (FBG) and Brillouin optical time domain reflectometry (BOTDR), into an integrated HMS for rehabilitated RC girder bridges by means of a series of static and dynamic loading tests to a simply supported RC T-beam strengthened by externally post-tensioned aramid fiber reinforced polymer (AFRP) tendons. Before the loading tests, a calibration test for FBG and another one for BOTDR were implemented to, respectively, obtain good linearity for both of them. Monitoring data were collected in real time during the process of external strengthening, static loading, and dynamic loading, respectively, all of which well identified the relevant structural state. The beam was finally vibrated for 2 million cycles and then loaded monotonously to failure. Based on the bending strength of externally prestressed members, ultimate values for the test specimen were numerically computed via a newly developed simplified model, which satisfactorily predicted the ultimate structural state of the beam. And then the alert values were adopted to compare with the monitoring results for safety alarm. The investigation results show a great deal of applicability for the integrated SHM by using both DOFS in rehabilitated concrete bridges strengthened by external prestressing. [source] The loose coupling mechanism in molecular machines of living cellsGENES TO CELLS, Issue 1 2000Fumio Oosawa Living cells have molecular machines for free energy conversion, for example, sliding machines in muscle and other cells, flagellar motors in bacteria, and various ion pumps in cell membranes. They are constructed from protein molecules and work in the nm (nanometer), pN (piconewton) and ms (millisecond) ranges, without inertia. In 1980s, a question was raised of whether the input,output or influx,efflux coupling in these molecular machines is tight or loose, and an idea of loose coupling was proposed. Recently, the long-distance multistep sliding of a single myosin head on an actin filament, coupled with the hydrolysis of one ATP molecule, was observed by Yanagida's group using highly developed techniques of optical microscopy and micromanipulation. This gave direct evidence for the loose coupling between the chemical reaction and the mechanical event in the sliding machine. In this review, I will briefly describe a historical overview of the input,output problem in the molecular machines of living cells. [source] Characterizing user-perceived impairment events using end-to-end measurementsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2005Soshant Bali Abstract Measures of quality of service (QoS) must correlate to end-user experience. For multimedia services, these metrics should focus on the phenomena that are observable by the end-user. Metrics such as delay and loss may have little direct meaning to the end-user because knowledge of specific coding and/or adaptive techniques is required to translate delay and loss to the user-perceived performance. Impairment events, as defined in this paper, are observable by the end-users independent of coding, adaptive playout or packet loss concealment techniques employed by their multimedia applications. Time between impairments and duration of impairments are metrics that are easily understandable by a network user. Methods to detect these impairment events using end-to-end measurements are developed here. In addition, techniques to identify Layer 2 route changes and congestion events using end-to-end measurements are also developed. These are useful in determining what caused the impairments. End-to-end measurements were conducted for about 26 days on 9 different node pairs to evaluate the developed techniques. Impairments occurred at a high rate on the two paths on which congestion events were detected. On these two paths, congestion occurred for 6,8 hours during the day on weekdays. Impairments caused by route changes were rare but lasted for several minutes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Frequency-multiplier design using negative-image device modelsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010Nam-Tae Kim Abstract This article presents a novel design methodology for wireless frequency multipliers using negative-image device models applicable to nonlinear devices. Negative-image device models of nonlinear devices are generated by incorporating optimization techniques into a hypothetical negative-image multiplier model. The negative-image device-modeling methodology provides the following advantages over previously developed techniques: (1) It can predict achievable multiplier performance in the device-modeling stage and (2) it provides an accurate starting point for the synthesis of impedance-matching networks. The negative-image device-modeling method is described, and its application to the design of a field-effect transistor (FET) frequency multiplier is presented. Results of an experimental implementation of the multiplier demonstrate the effectiveness of the proposed methodology. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2544,2548, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25521 [source] Delay-dependent robust passive control for a class of nonlinear systems with time-varying delaysOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5 2008Jiqing Qiu Abstract In this paper, the problem of robust passive control for a class of nonlinear systems with time-varying delays is considered. The uncertainties investigated in this paper are norm bounded and time varying, and they enter all system matrices. Based on the Lyapunov,Krasovskii functionals approach, a new robust passive control criterion is proposed in terms of linear matrix inequalities, which is dependent on the size of time delay. We also design a state feedback controller that guarantees a robust asymptotically stable and strictly passive closed-loop system for all admissible uncertainties. Finally, two numerical examples are given to illustrate the effectiveness of the developed techniques. Copyright © 2007 John Wiley & Sons, Ltd. [source] THE COMPOSITION AND MANUFACTURE OF EARLY MEDIEVAL COLOURED WINDOW GLASS FROM SION (VALAIS, SWITZERLAND),A ROMAN GLASS-MAKING TRADITION OR INNOVATIVE CRAFTSMANSHIP?*ARCHAEOMETRY, Issue 2 2005S. WOLF Archaeological excavations between 1984 and 2001 at the early Christian cemetery church in Sion, Sous-le-Scex (Rhône Valley, Switzerland), brought to light more than 400 pieces of coloured window glass dating from the fifth or sixth centuries ad. The aims of this paper are threefold: first, to characterize the shape, colour and chemical composition of the glass; secondly, to understand whether the production of the coloured window panes followed traditional Roman glazing techniques or was of a more innovative nature; and, thirdly, to provide some indications as to the overall design of these early ornamental glass windows. Forty samples of coloured glass have been analysed by wavelength-dispersive X-ray fluorescence. The results of the chemical and the technological studies showed that most of the glass was produced using recycled glass, particularly as a colouring agent. Some of the glass was made of essentially unmodified glass of the Levantine I type. The results taken together seem to confirm that raw glass from this region was widely traded and used between the fourth and seventh centuries ad. The artisans at Sion were apparently still making use of the highly developed techniques of Roman glass production. The colour spectrum, manufacture and design of the windows, however, suggest that they represent early examples of ornamental coloured glass windows. [source] Fault tolerant control design via hybrid petri nets,ASIAN JOURNAL OF CONTROL, Issue 5 2010Hao Yang Abstract This paper proposes a novel fault tolerant control (FTC) scheme for hybrid systems modeled by hybrid Petri nets (HPNs). The HPNs model consists of discrete and continuous PNs. The faults are represented by unobservable discrete transitions or the normal observable discrete transitions with abnormal firing time in discrete PNs. First, an observer-based fault diagnosis method is proposed to estimate the marking in discrete places with unknown initial marking and diagnose the faulty behavior simultaneously. Then, an adaptive fault tolerant controller is designed to maintain the general mutual exclusion constraints (GMEC) of discrete PNs, and a scheme that adjusts firing speeds of continuous transitions is provided to maintain the optimality of continuous PNs. Finally, an example of an intelligent transportation system consisting of automated vehicles on a bridge is included to demonstrate the effectiveness of our developed techniques. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] | ||||||||||