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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Behavior of Full-Scale Reinforced Concrete Members with External Confinement or Internal Composite Reinforcement under Pure Axial Load

De Luca, Antonio 21 December 2009 (has links)
The need to satisfy aerospace industry's demand not met by traditional materials motivated researchers and scientists to look for new solutions. The answer was found in developing new material systems by combining together two or more constituents. Composites, also known as fiber reinforced polymers (FRP) consisting of a reinforcing phase (fibers) embedded into a matrix (polymer), offered several advantages with respect to conventional materials. High specific modulus and strength together with other beneficial properties, corrosion resistance and transparency to electrical and magnetic fields above all, made FRP also suitable for use as construction materials in structural engineering. In the early years of the twenty-first century, the publication by the American Concrete Institute (ACI) of design guidelines for the use of FRP as internal reinforcement and for external strengthening of concrete members accelerated their implementation for structural engineering applications. To date, FRP have gained full acceptance as advanced materials for construction and their use is poised to become as routine as the use of conventional structural materials such as masonry, wood, steel, and concrete. However, new concrete columns internally reinforced with FRP bars and FRP confinement for existing prismatic reinforced concrete (RC) columns have currently important unsolved issues, some of which are addressed in this dissertation defense. The dissertation is articulated on three studies. The first study (Study 1) focuses on RC columns internally reinforced with glass FRP (GFRP) bars; the second (Study 2) on RC prismatic columns externally confined by means of FRP laminates using glass and glass/basalt fibers; and the third (Study 3) is a theoretical attempt to interpret and capture the mechanics of the external FRP confinement of square RC columns. Study 1 describes an experimental campaign on full-scale GFRP RC columns under pure axial load undertaken using specimens with a 24 by 24 in. (0.61 by 0.61 m) square cross section. The study was conducted to investigate whether the compressive behavior of longitudinal GFRP bars impacts the column performance, and to understand the contribution of GFRP ties to the confinement of the concrete core, and to prevent instability of the longitudinal reinforcement. The results showed that the GFRP RC specimens behaved similarly to the steel RC counterpart, while the spacing of the ties strongly influenced the failure mode. Study 2 presents a pilot research that includes laboratory testing of full-scale square and rectangular RC columns externally confined with glass and basalt-glass FRP laminates and subjected to pure axial load. Specimens that are representative of full-scale building columns were designed according to a dated ACI 318 code (i.e., prior to 1970) for gravity loads only. The study was conducted to investigate how the external confinement affects ultimate axial strength and deformation of a prismatic RC column. The results showed that the FRP confinement increases concrete axial strength, but it is more effective in enhancing concrete strain capacity. The discussion of the results includes a comparison with the values obtained using existing constitutive models. Study 3 proposes a new theoretical framework to interpret and capture the physics of the FRP confinement of square RC columns subjected to pure compressive loads. The geometrical, physical and mechanical parameters governing the problem are analyzed and discussed. A single-parameter methodology for predicting the axial stress - axial strain curve for FRP-confined square RC columns is described. Fundamentals, basic assumptions and limitations are discussed. A simple design example is also presented.
272

Physical and Mental Health Interventions in a Rural, School-Based Setting: A comparative analysis of academic performance, behavioral outcomes, and attendance

parris, heather n 01 August 2010 (has links)
Abstract The purpose of this study was to determine the differences in academic achievement, behavioral health outcomes and attendance in poor, rural children receiving physical and mental health services regularly as opposed to those children not receiving the intervention. The intervention was a school-based health and mental health clinic located on the school’s campus. This study was analyzed by providing descriptive information for several variables including the number of suspensions per year, number of times corporal punishment was used as a means of correction, educational outcomes, total number of clinic visits per year, attendance percentages per year, and number of teacher and parent referrals to the school clinic. Data for this study were presented in multiple charts and graphs and schools are compared using descriptive information. The results suggested that as the number of clinic visits increased across the three year period, the numbers of, and rates of, corporal punishment in the clinic school decreased. In contrast, the available data suggested that across the first two years the numbers of, and rates of, corporal punishment increased in the control school. Further, in the majority of subject areas, the percentage of students’ proficiency levels in the clinic school increased across time and the percentages exceeded these in the control school. These findings were consistent with the hypotheses that there will be improvements in the behavioral outcomes associated with the presence of the clinic in the school. Unfortunately there were not enough data to conduct a test of statistical significance of the differences between schools for the third year.
273

Enhancing the understanding of healing through a seminar /

Lee, Il-Seung. January 2004 (has links)
Applied research project (D. Min.)--School of Theology and Missions, Oral Roberts University, 2004. / Includes abstract. Translated from Korean. Includes bibliographical references (leaves 249-257).
274

[Enhancing the understanding of healing through a seminar] /

Lee, Il-Seung. January 2004 (has links)
Applied research project (D. Min.)--School of Theology and Missions, Oral Roberts University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 184-191).
275

Conducting Online Research Undergraduate Preferences of Sources.

Rosalyn Metz 2006 April 1900 (has links)
When students write research papers they use a variety of sources in their paper. These sources range from web pages to research articles. The purpose of this study was to decide whether or not undergraduate students would choose to use scholarly or non-scholarly sources when presented with both types of sources in a set of search results. Twenty Duke University students were recruited for the study. They were given a research topic and asked to perform a search. Both the search results and interface were fabricated by the researcher in order to control the experimental environment. The students were asked to rate the sources found in the results, choose four sources to use for their research scenario, and finally, were asked to explain reasoning behind their choices. The findings concluded that the students in this study were more likely to choose scholarly sources over non-scholarly sources and give these scholarly sources higher ratings.
276

Développement d'une méthode de reconstruction ultrasonore pour la localisation et la caractérisation de défauts

Fidahoussen, Alex 21 September 2012 (has links) (PDF)
Les techniques de contrôle non-destructif s'appuyant sur des traducteurs ultrasons multi-éléments sont maintenant de plus en plus utilisées dans l'industrie. Ces traducteurs offrent en effet de nombreux avantages, en particulier une polyvalence d'utilisation et une adaptabilité à des configurations complexes. De plus des techniques d'acquisition avancées, telle que la Full Matrix Capture, permettent d'avoir accès à des données beaucoup plus riches et complètes que celles fournies par les techniques conventionnelles, offrant ainsi de nouvelles possibilités en terme de localisation et de caractérisation de défauts. Les travaux de cette thèse ont pour objectif de mettre en œuvre des méthodes d'imagerie et de reconstruction adaptées aux diverses acquisitions multi-éléments possibles. Pour cela, nous proposons différentes méthodes dérivées de l'approche dite de focalisation synthétique. Ces méthodes s'appuient sur des modèles directs développés au CEA LIST et implémentés dans la plateforme CIVA. Ces derniers peuvent, en outre, prendre en compte les configurations de contrôle complexes, notamment en ce qui concerne l'état de surface -irrégulier- des pièces inspectées. Dans un premier temps, nous nous sommes intéressés à la localisation de diffracteur quasi-ponctuel. Sous cette hypothèse, nous avons évalués les performances des méthodes proposées lorsqu'elles sont appliquées à différents types d'acquisitions. La suite des travaux s'est recentrée sur l'étude de la Full Matrix Capture couplée à l'algorithme dit de " Focalisation en Tous Points (FTP) ", cette combinaison ayant montré de bonnes performances en terme de localisation. Dans un second temps, nous avons prolongé notre approche à la reconstruction de défauts étendus et à la prise en compte de trajets ultrasonores multiples. En particulier, nous avons appliqué la généralisation de l'algorithme FTP à la localisation et à la caractérisation d'entaille proche du fond de la pièce à l'aide d'échos de coin, échos dus à des réflexions successives de l'onde ultrasonore sur le fond et le défaut. Les différentes méthodes envisagées dans ces travaux ont été appliquées avec des données simulées ainsi qu'avec des mesures expérimentales.
277

An Empirical Analysis of Family Cost of Children : A Comparison of Ordinary Least Square Regression and Quantile Regression

Li, Yang January 2010 (has links)
Quantile regression have its advantage properties comparing to the OLS model regression which are full measurement of the effects of a covariate on response, robustness and Equivariance property. In this paper, I use a survey data in Belgium and apply a linear model to see the advantage properites of quantile regression. And I use a quantile regression model with the raw data to analyze the different cost of family on different numbers of children and apply a Wald test. The result shows that for most of the family types and living standard, from the lower quantile to the upper quantile the family cost on children increases along with the increasing number of children and the cost of each child is the same. And we found a common behavior that the cost of the second child is significantly more than the cost of the first child for a nonworking type of family and all living standard families, at the upper quantile (from 0.75 quantile to 0.9 quantile) of the conditional distribution.
278

Energy Calibration of Different Modes of a pn-CCD-camera on board the X-Ray Observatory XMM-Newton

Winroth, Gustaf January 2007 (has links)
The X-ray Multi-mirror Mission, XMM-Newton was launched by the European Space Agency, ESA, in 1999. XMM-Newton carries six cameras, including a silicon pn-junction Charge Coupled Device, or pn-CCD camera. This camera has six operating modes, spatially as well as time resolved. The main objective of this project is to refine the Burst mode energy correction in order to align the measured energy spectra observed in the Burst mode with the spectra taken in the Full Frame mode. An observation of the line-rich supernova remnant called Cassiopeia A is used to evaluate the line positions in each mode such that the energy correction function used for the alignment can be modified accordingly. The analysis further treats the application of the correction on a source with a continuous spectrum, the Crab nebula. Discussion shows how to reduce eventual residuals in the Crab spectrum by modifying the correction function while keeping the alignment of the Cas-A spectra. The final product is an update of the corresponding published calibration file.
279

Mild Hybrid System in Combination with Waste Heat Recovery for Commercial Vehicles

Namakian, Mohsen January 2013 (has links)
Performance of two different waste heat recovery systems (one based on Rankine cycle and the other one using thermoelectricity) combined with non-hybrid, mild-hybrid and full hybrid systems are investigated. The vehicle under investigation was a 440hp Scania truck, loaded by 40 tons. Input data included logged data from a long haulage drive test in Sweden.All systems (waste heat recovery as well as hybrid) are implemented and simulated in Matlab/Simulink. Almost all systems are modeled using measured data or performance curves provided by one manufacturer. For Rankine system results from another investigation were used.Regardless of practical issues in implementing systems, reduction in fuel consumption for six different combination of waste heat recovery systems and hybrid systems with different degrees of hybridization are calculated. In general Rankine cycle shows a better performance. However, due to improvements achieved in laboratories, thermoelectricity could also be an option in future.This study focuses on “system” point of view and therefore high precision calculations is not included. However it can be useful in making decisions for further investigations.
280

低出生体重児の社会的発達に関する研究の概観

NAGATA, Masako, YAMASHITA, Saori, 永田, 雅子, 山下, 沙織 28 December 2012 (has links)
No description available.

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