402 research outputs found

    A study of the stress wave factor technique for evaluation of composite materials

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    The acousto-ultrasonic approach for nondestructive evaluation provides a measurement procedure for quantifying the integrated effect of globally distributed damage characteristic of fiber reinforced composite materials. The evaluation procedure provides a stress wave factor that correlates closely with several material performance parameters. The procedure was investigated for a variety of materials including advanced composites, hybrid structure bonds, adhesive bonds, wood products, and wire rope. The research program focused primarily on development of fundamental understanding and applications advancements of acousto-ultrasonics for materials characterization. This involves characterization of materials for which detection, location, and identification of imperfections cannot at present be analyzed satisfactorily with mechanical performance prediction models. In addition to presenting definitive studies on application potentials, the understanding of the acousto-ultrasonic method as applied to advanced composites is reviewed

    Accounting for externalities in the measurement of productivity growth: The Malmquist cost productivity measure

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    This paper starts with the basic premise: that conventional measures of productivity growth-often used as a measure of corporate performance-which ignore external or social output, are biased. We then construct an alternative productivity growth measure using activity analysis which integrates the externality/social output into a generalized productivity measure reflecting social responsibility. This method is very general and could be applied to gauge corporate social responsibility. We provide an application to US agriculture to demonstrate the approach: We show that conventional measures of productivity are biased upward when production of negative externalities (or bad) outputs is increasing. Conversely, this same measure of productivity is biased downward when externalities in production are decreasing. © 2004 Elsevier B.V. All rights reserved

    Road safety assessments and road safety audits on the existing Abu Dhabi Internal road network

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    Paper presented at the 31st Annual Southern African Transport Conference 9-12 July 2012 "Getting Southern Africa to Work", CSIR International Convention Centre, Pretoria, South Africa.Road safety auditing is a process to pro-actively review the potential for road safety improvements on any road or transportation project, whether in a design phase or as an existing road facility. The process is based on the critical assessment of the project features as they would be experienced by any road user. ARRB Group Ltd (ARRB, the Australian Road Research Board) in co-operation with Parsons International Ltd (PIL) conducted road safety audits on a selection of the internal road network of the Municipality of Abu Dhabi City, UAE. The project was conducted in 2011 and consisted of various tasks: • Conducting a network level road safety assessment of 2 600 carriageway-km of roads and streets to identify high risk areas; • Conducting road safety audits on a sub-set of roads and streets of about 300 carriageway-km forming part of the high risk areas; • Recommending remedial measures; • Developing program level cost estimates for remedial treatments • Prioritising remedial treatments based on their cost effectiveness The network level road safety assessment had been conducted using the Hawkeye video survey system and the risk levels of different sections of the network determined by utilizing the proprietary NetRisk software. Available crash information was superimposed on maps showing the network risk levels. In this manner a clear impression could be formed of those areas where safety concerns existed, based on the pro-active review of road features in the road safety assessment process in coordination with the reactive process of crash analysis. Road safety audits were then conducted on the areas with the highest risk levels. The audits were undertaken by combining traditional on-site reviews with a comprehensive geo-referenced inventory of road safety problems extracted from the video surveys. A first order estimate of the cost of the works to remedy the safety concerns on the 300 carriageway-km of audited roads and streets indicated a programme value in excess of USD 93,5Million1 (at 2011 prices).This paper was transferred from the original CD ROM created for this conference. The material was published using Adobe Acrobat 10.1.0 Technology. The original CD ROM was produced by Document Transformation Technologies Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: nigel@doctech URL: http://www.doctech.co.zadm201

    Dual, orthogonal, backlit pinhole radiography in OMEGA experiments

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    Backlit pinhole radiography used with ungated film as a detector creates x-ray radiographs with increased resolution and contrast. Current hydrodynamics experiments on the OMEGA Laser use a three-dimensional sinusoidal pattern as a seed perturbation for the study of instabilities. The structure of this perturbation makes it highly desirable to obtain two simultaneous orthogonal backlighting views. We accomplished this using two backlit pinholes each mounted 12 mm12mm from the target. The pinholes, of varying size and shape, were centered on 5 mm5mm square foils of 50 μm50μm thick Ta. The backlighting is by KK-alpha emission from a 500 μm500μm square Ti or Sc foil mounted 500 μm500μm from the Ta on a plastic substrate. Four laser beams overfill the metal foil, so that the expanding plastic provides radial tamping of the expanding metal plasma. The resulting x-rays pass through the target onto (ungated) direct exposure film (DEF). Interference between the two views is reduced by using a nose cone in front of the DEF, typically with a 9 mm9mm Ta aperture and with magnets to deflect electrons. Comparison of varying types of pinholes and film exposures will be presented from recent experiments as well as an analysis of the background noise created using this experimental technique.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87894/2/10E327_1.pd
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