848 resultados para NonDestructive Evaluation, Compressive Sensing, Lamb waves, Structural Health Monitoring
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ABSTRACT: Background: Childhood is a critical time for social and emotional development, educational progress and mental health prevention. Mental health for children and adolescents is defined by the achievement of expected developmental, cognitive, social and emotional skills. The development of child-adolescent mental health services (CAMHS) is a necessity for each country, not only as a prevention measure for the wellbeing of people, but also as an investment to the future of countries. Qualitative evaluation of services is the only way to ensure whether services function under quality standards and increase the possibility of better outcomes for their patients. This study examines the greek outpatient CAMHS against the British Standards of National Institute of Excellence for community CAMHS. The Standards assessed refer to the areas of Assessment, Care and Intervention. Objectives: The main objectives of the study are 1) to evaluate Greek outpatient CAMHS in the Attica region 2) to promote the evaluation process for mental health services in Greece. Methods: Due to the fact that Greek services are based on the British model, the tool used was the British self-review questionnaire of Quality Network for Community CAMHS(QNCC).The tool was translated, adapted and posted to services. Twelve out of twenty outpatient CAMHS of Attica (including Athens) responded. Data was collected and performed by the Statistical Package for Social Sciences SPSS. Results: The study resulted that the CAMHS examined, meet moderately the British Standards of 1) Referral and Access, 2) Assessment & Care planning, 3) Care & Intervention. Two out of twelve services examined, meet the standards of "Assessment and Care" in a higher percentage between 75% and 100%. Conclusions: The paper describes a satisfactory function of CAMHS in Attica prefecture taking into consideration the extremely difficult political situation of Greece at the time of the research. Strong and weak domains are identified. Also the translation and adaptation of British tools promote the evaluation process and quality assurance of Greek CAMHS.
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Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2011
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Of the approximately 25,000 bridges in Iowa, 28% are classified as structurally deficient, functionally obsolete, or both. Because many Iowa bridges require repair or replacement with a relatively limited funding base, there is a need to develop new bridge materials that may lead to longer life spans and reduced life-cycle costs. In addition, new and effective methods for determining the condition of structures are needed to identify when the useful life has expired or other maintenance is needed. Due to its unique alloy blend, high-performance steel (HPS) has been shown to have improved weldability, weathering capabilities, and fracture toughness than conventional structural steels. Since the development of HPS in the mid-1990s, numerous bridges using HPS girders have been constructed, and many have been economically built. The East 12th Street Bridge, which replaced a deteriorated box girder bridge, is Iowa’s first bridge constructed using HPS girders. The new structure is a two-span bridge that crosses I-235 in Des Moines, Iowa, providing one lane of traffic in each direction. A remote, continuous, fiber-optic based structural health monitoring (SHM) system for the bridge was developed using off-the-shelf technologies. In the system, sensors strategically located on the bridge collect raw strain data and then transfer the data via wireless communication to a gateway system at a nearby secure facility. The data are integrated and converted to text files before being uploaded automatically to a website that provides live strain data and a live video stream. A data storage/processing system at the Bridge Engineering Center in Ames, Iowa, permanently stores and processes the data files. Several processes are performed to check the overall system’s operation, eliminate temperature effects from the complete strain record, compute the global behavior of the bridge, and count strain cycles at the various sensor locations.
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OBJECTIVE: To extract and to validate a brief version of the DISCERN which could identify mental health-related websites with good content quality. METHOD: The present study is based on the analysis of data issued from six previous studies which used DISCERN and a standardized tool for the evaluation of content quality (evidence-based health information) of 388 mental health-related websites. After extracting the Brief DISCERN, several psychometric properties (content validity through a Factor analysis, internal consistency by the Cronbach's alpha index, predictive validity through the diagnostic tests, concurrent validity by the strength of association between the Brief DISCERN and the original DISCERN scores) were investigated to ascertain its general applicability. RESULTS: A Brief DISCERN composed of two factors and six items was extracted from the original 16 items version of the DISCERN. Cronbach's alpha coefficients were more than acceptable for the complete questionnaire (alpha=0.74) and for the two distinct domains: treatments information (alpha=0.87) and reliability (alpha=0.83). Sensibility and specificity of the Brief DISCERN cut-off score > or =16 in the detection of good content quality websites were 0.357 and 0.945, respectively. Its predictive positive and negative values were 0.98 and 0.83, respectively. A statistically significant linear correlation was found between the total scores of the Brief DISCERN and those of the original DISCERN (r=0.84 and p<0.0005). CONCLUSION: The Brief DISCERN seems to be a reliable and valid instrument able to discriminate between websites with good and poor content quality. PRACTICE IMPLICATIONS: The Brief DISCERN is a simple tool which could facilitate the identification of good information on the web by patients and general consumers.
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This report is divided into two volumes. This volume (Volume I) summarizes a structural health monitoring (SHM) system that was developed for the Iowa DOT to remotely and continuously monitor fatigue critical bridges (FCB) to aid in the detection of crack formation. The developed FCB SHM system enables bridge owners to remotely monitor FCB for gradual or sudden damage formation. The SHM system utilizes fiber bragg grating (FBG) fiber optic sensors (FOSs) to measure strains at critical locations. The strain-based SHM system is trained with measured performance data to identify typical bridge response when subjected to ambient traffic loads, and that knowledge is used to evaluate newly collected data. At specified intervals, the SHM system autonomously generates evaluation reports that summarize the current behavior of the bridge. The evaluation reports are collected and distributed to the bridge owner for interpretation and decision making. Volume II summarizes the development and demonstration of an autonomous, continuous SHM system that can be used to monitor typical girder bridges. The developed SHM system can be grouped into two main categories: an office component and a field component. The office component is a structural analysis software program that can be used to generate thresholds which are used for identifying isolated events. The field component includes hardware and field monitoring software which performs data processing and evaluation. The hardware system consists of sensors, data acquisition equipment, and a communication system backbone. The field monitoring software has been developed such that, once started, it will operate autonomously with minimal user interaction. In general, the SHM system features two key uses. First, the system can be integrated into an active bridge management system that tracks usage and structural changes. Second, the system helps owners to identify damage and deterioration.
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Wiss, Janney, Elstner Associates, Inc. (WJE) evaluated potential nondestructive evaluation (NDE) methodologies that may be effective in 1) identifying internal defects within slip formed concrete barriers and 2) assessing the corrosion condition of barrier dowel bars. The evaluation was requested by the Bridge Maintenance and Inspection Unit of the Iowa Department of Transportation (IaDOT) and the Bureau of Bridges and Structures of the Illinois Department of Transportation (IDOT). The need arose due to instances in each Department’s existing inventory of bridge barriers where internal voids and other defects associated with slip forming construction methods were attributed to poor barrier performance after completion of construction and where, in other barrier walls, unintentional exposure of the dowel bars revealed extensive corrosion-related section loss at previously uninspectable locations, reducing the capacity of the barriers to resist traffic impact loads. WJE trial tested potential NDE techniques on laboratory mock-up samples built with known defects, trial sections of cast-in-place barriers at in-service bridges in Iowa, and slip formed and cast-in-place barrier walls at in-service bridges in Illinois. The work included review of available studies performed by others, field trial testing to assess candidate test methods, verification of the test methods in identifying internal anomalies and dowel bar corrosion, and preparation of this report and nondestructive evaluation guidelines.
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This work present the application of a computer package for generating of projection data for neutron computerized tomography, and in second part, discusses an application of neutron tomography, using the projection data obtained by Monte Carlo technique, for the detection and localization of light materials such as those containing hydrogen, concealed by heavy materials such as iron and lead. For tomographic reconstructions of the samples simulated use was made of only six equal projection angles distributed between 0º and 180º, with reconstruction making use of an algorithm (ARIEM), based on the principle of maximum entropy. With the neutron tomography it was possible to detect and locate polyethylene and water hidden by lead and iron (with 1cm-thick). Thus, it is demonstrated that thermal neutrons tomography is a viable test method which can provide important interior information about test components, so, extremely useful in routine industrial applications.
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X-rays were initially used for the inspection of special-purpose wood pieces for quantitative evaluation properties of different species. X-ray densitometry has had its use expanded ill dendroclimatology of Picea engelmannii trees. Subsequent laboratories developed applications of X-ray densitometry for environmental, wood science and technology, and related areas. This paper describes the basic methodology of X-ray densitometry applied to the eucalypt wood analysis, as well its presenting the results of applications in three areas: (i) evaluation of wood biodegradation by white rot fungi, (ii) detection of sapwood and heartwood, and (iii) determination of the effect of management oil wood properties. The wood decayed by white rot fungi was detected by X-ray densitometry with it decreasing wood density due to the biodegradation of cell wall components. The sapwood and heartwood of eucalypts were separated in response to the attenuation of X-rays, reflected by the wood anatomical structure and chemical composition. Also, Ill eucalypt trees after the application of irrigation and i characteristic wood density profiles were detected. Ill addition, the significant potential of X-ray densitometry for eucalypt wood research and analysis is discussed.
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Pós-graduação em Engenharia Mecânica - FEIS
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It is usual to hear a strange short sentence: «Random is better than...». Why is randomness a good solution to a certain engineering problem? There are many possible answers, and all of them are related to the considered topic. In this thesis I will discuss about two crucial topics that take advantage by randomizing some waveforms involved in signals manipulations. In particular, advantages are guaranteed by shaping the second order statistic of antipodal sequences involved in an intermediate signal processing stages. The first topic is in the area of analog-to-digital conversion, and it is named Compressive Sensing (CS). CS is a novel paradigm in signal processing that tries to merge signal acquisition and compression at the same time. Consequently it allows to direct acquire a signal in a compressed form. In this thesis, after an ample description of the CS methodology and its related architectures, I will present a new approach that tries to achieve high compression by design the second order statistics of a set of additional waveforms involved in the signal acquisition/compression stage. The second topic addressed in this thesis is in the area of communication system, in particular I focused the attention on ultra-wideband (UWB) systems. An option to produce and decode UWB signals is direct-sequence spreading with multiple access based on code division (DS-CDMA). Focusing on this methodology, I will address the coexistence of a DS-CDMA system with a narrowband interferer. To do so, I minimize the joint effect of both multiple access (MAI) and narrowband (NBI) interference on a simple matched filter receiver. I will show that, when spreading sequence statistical properties are suitably designed, performance improvements are possible with respect to a system exploiting chaos-based sequences minimizing MAI only.
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The research presented in this thesis was conducted to further the development of the stress wave method of nondestructively assessing the quality of wood in standing trees. The specific objective of this research was to examine, in the field, use of two stress wave nondestructive assessment techniques. The first technique examined utilizes a laboratory-built measurement system consisting of commercially available accelerometers and a digital storage oscilloscope. The second technique uses a commercially available tool that incorporates several technologies to determine speed of stress wave propagation in standing trees. Field measurements using both techniques were conducted on sixty red pine trees in south-central Wisconsin and 115 ponderosa pine trees in western Idaho. After in-situ measurements were taken, thirty tested red pine trees were felled and a 15-foot-long butt log was obtained from each tree, while all tested ponderosa pine trees were felled and an 8 1/2 -foot-long butt log was obtained, respectively. The butt logs were sent to the USDA Forest Products Laboratory and nondestructively tested using a resonance stress wave technique. Strong correlative relationships were observed between stress wave values obtained from both field measurement techniques. Excellent relationships were also observed between standing tree and log speed-of-sound values.
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Routine bridge inspections require labor intensive and highly subjective visual interpretation to determine bridge deck surface condition. Light Detection and Ranging (LiDAR) a relatively new class of survey instrument has become a popular and increasingly used technology for providing as-built and inventory data in civil applications. While an increasing number of private and governmental agencies possess terrestrial and mobile LiDAR systems, an understanding of the technology’s capabilities and potential applications continues to evolve. LiDAR is a line-of-sight instrument and as such, care must be taken when establishing scan locations and resolution to allow the capture of data at an adequate resolution for defining features that contribute to the analysis of bridge deck surface condition. Information such as the location, area, and volume of spalling on deck surfaces, undersides, and support columns can be derived from properly collected LiDAR point clouds. The LiDAR point clouds contain information that can provide quantitative surface condition information, resulting in more accurate structural health monitoring. LiDAR scans were collected at three study bridges, each of which displayed a varying degree of degradation. A variety of commercially available analysis tools and an independently developed algorithm written in ArcGIS Python (ArcPy) were used to locate and quantify surface defects such as location, volume, and area of spalls. The results were visual and numerically displayed in a user-friendly web-based decision support tool integrating prior bridge condition metrics for comparison. LiDAR data processing procedures along with strengths and limitations of point clouds for defining features useful for assessing bridge deck condition are discussed. Point cloud density and incidence angle are two attributes that must be managed carefully to ensure data collected are of high quality and useful for bridge condition evaluation. When collected properly to ensure effective evaluation of bridge surface condition, LiDAR data can be analyzed to provide a useful data set from which to derive bridge deck condition information.
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Introduction: The Texas Occupational Safety & Health Surveillance System (TOSHSS) was created to collect, analyze and interpret occupational injury and illness data in order to decrease the impact of occupational injuries within the state of Texas. This process evaluation was performed midway through the 4-year grant to assess the efficiency and effectiveness of the surveillance system’s planning and implementation activities1. ^ Methods: Two evaluation guidelines published by the Centers for Disease Control and Prevention (CDC) were used as the theoretical models for this process evaluation. The Framework for Program Evaluation in Public Health was used to examine the planning and design of TOSHSS using logic models. The Framework for Evaluating Public Health Surveillance Systems was used to examine the implementation of approximately 60 surveillance activities, including uses of the data obtained from the surveillance system. ^ Results/Discussion: TOSHSS planning activities omitted the creation of a scientific advisory committee and specific activities designed to maintain contacts with stakeholders; and proposed activities should be reassessed and aligned with ongoing performance measurement criteria, including the role of collaborators in helping the surveillance system achieve each proposed activity. TOSHSS implementation activities are substantially meeting expectations and received an overall score of 61% for all activities being performed. TOSHSS is considered a surveillance system that is simple, flexible, acceptable, fairly stable, timely, moderately useful, with good data quality and a PVP of 86%. ^ Conclusions: Through the third year of TOSHSS implementation, the surveillance system is has made a considerable contribution to the collection of occupational injury and illness information within the state of Texas. Implementation of the nine recommendations provided under this process evaluation is expected to increase the overall usefulness of the surveillance system and assist TDSHS in reducing occupational fatalities, injuries, and diseases within the state of Texas. ^ 1 Disclaimer: The Texas Occupational Safety and Health Surveillance System is supported by Grant/Cooperative Agreement Number (U60 OH008473-01A1). The content of the current evaluation are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health.^
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The latest technology and architectural trends have significantly improved the use of a large variety of glass products in construction which, in function of their own characteristocs, allow to design and calculate structural glass elements under safety conditions. This paper presents the evaluation and analysis of the damping properties of rectangular laminated glass plates of 1.938 m x 0.876 m with different thickness depending on the number of PVB interlayers arranged. By means of numerical simulation and experimental verification, using modal analysis, natural frequencies and damping of the glass plates were calculated, both under free boundary conditions and operational conditions for the impact test equipment used in the experimental program, as the European standard UNE-EN 12600:2003 specifies.