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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.
451

Development of an Investigator-designed Questionnaire Concerning Childbirth Delivery Options based on the Theory of Planned Behavior

Tai, Chun-Yi 01 January 2013 (has links)
This study responds to the globally increasing rate of caesarean section, and specifically to the very high rate of elective caesarean section among Taiwanese mothers as evidence suggests that such elective caesareans pose potential health risks for mothers and babies. The purpose of this study was to develop and evaluate a multi-component instrument based on the theory of planned behavior (TPB) to better understand Taiwanese pregnant women's decisions regarding their childbirth delivery options (spontaneous vaginal delivery or elective caesarean section). The study was a four-phased mixed method design. First, the TPB guided item development and instrument drafting. Second, pretesting and instrument refinement used cognitive interviewing with a small sample of Taiwanese pregnant women. Third, the instrument was administered to 310 such women to examine psychometric properties of the component scales. Fourth, the phase 3 instrument was re-administered to 30 women to estimate item stability. Confirmatory factor analyses (CFA) were used to assess construct validity of the multi-item, multi-component measurement model with LISREL 9.1. Based on the TPB, the 52-item self-administered Childbirth Delivery Options Questionnaire (CDOQ) was developed to measure three components: intention regarding delivery options, attitudes toward delivery options, and perceptions of significant others' (partner, mother, and mother-in-law) feelings about delivery options. Respondents from phase two thought that the items on the CDOQ were easy to read and comprehend; they reported favorably on the wording and formatting. Preliminary item analysis revealed that the items referring to dangerousness of delivery options did not function as intended and were dropped because they did not differentiate between the two delivery options, leaving 36 items. Test-retest reliability indicated that responses to each item were positively correlated and those referring to spontaneous vaginal delivery were more stable than those referring to elective caesarean section. Corrected item-to-total correlations and expected change in Cronbach's alpha if item deleted revealed that four items might form a measure of general social norms associated with the Taiwanese culture. The Cronbach's alphas for the components of the CDOQ ranged from .55 to .89. The measurement model incorporating the design features of the CDOQ fitted the data well using the CFA. Because serious problems with multicollinearity and suppression were revealed, Beckstead's (2012) criterion-irrelevant-variance-omitted (CIVO) regression method was used to untangle the suppressor effects when predicting intention from the other components of the CDOQ. The results indicated that attitude and partner's feelings were significant and explained the bulk of the variance in intentions. The TPB-based instrument developed here will be of considerable use to maternal-child health researchers. The findings of this study suggest that decisions regarding delivery options may be modified by interventions geared toward pregnant women's attitudes within family- and cultural-centered prenatal programs.
452

Traditional Cultural Properties : a potential tool for community-driven historic preservation / Potential tool for community-driven historic preservation

Lapham, Rebecca Scott 07 June 2012 (has links)
National Register Bulletin 38: Guidelines for Evaluating and Documenting Traditional Cultural Properties was first published in 1990 as a response to the Secretary of the Interior's report Cultural Conservation. Submitted to Congress and the President in 1983, Cultural Conservation "recommended in general that traditional cultural resources...be more systematically addressed in implementation of the National Historic Preservation Act and other historic preservation authorities." Bulletin 38 defined Traditional Cultural Properties (TCPs), as those "whose significance is derived from the role the property plays in a community's historically rooted beliefs, customs, and practices." Bulletin 38 provides guidance in determining whether properties of traditional cultural significance are potentially eligible for inclusion in the National Register of Historic Places (NRHP). This thesis investigates whether or not the NRHP Criteria, and guidelines set forth in Bulletin 38, provide adequate protection for non-tribal TCPs under the NHPA. An outline of applicable federal regulations and procedures for identification and evaluation of historic properties provides a framework for evaluating TCPs. Examination of four cases studies, Mt. Graham, Bighorn Medicine Wheel/Medicine Mountain, the Dune Shacks of the Peaked Hill Bars, and Gladesmen Folk Culture, illustrates several fundamental difficulties in the treatment of TCPs. First, emphasis on professionalization within the fields of Cultural Resource Management and Historic Preservation has discouraged consideration of community perspectives in the identification and evaluation of both tribal and non-tribal historic sites. Second, divergent viewpoints between federal agencies, Native American tribes, professional practitioners, and individual communities prevent meaningful consultation and cooperation. Third, the existing standards and guidelines for identification and evaluation of TCPs are vague, and subject to variable interpretation. Finally, a conflict of interest exists between agencies and communities when considering properties located on federally owned land. In order for TCPs, especially non-tribal TCP's, to receive adequate attention and protection agencies and professionals need to change how they implement and interpret the procedures and guidelines set forth in the NHPA. This thesis concludes with suggestions for improving the process of identifying and evaluating non-tribal TCPs. It advocates creating independent, regional sub-committees to make informed recommendations and determinations of eligibility for TCPs located on federally owned land. Finally, it outlines strategies for promoting more community involvement in the NRHP review process through training programs administered by the Advisory Council on Historic Preservation. / text
453

A multi-region collision probability method for determining neutron spectra and reaction rates

Dembia, Christopher Lee 06 November 2012 (has links)
The collision probability approach to neutron transport can be used to obtain the energy-dependent neutron spectrum in nuclear reactor systems as well as other quantities of interest. This method makes the approximation that the neutron distribution is constant within homogeneous regions, or cells, in the system. This assumption restricts geometries that can be modeled by the collision probability approach. The geometry modeled is typically an infinite lattice of two homogeneous cells: a fuel pin cylinder and the coolant that surrounds it. The transport of neutrons between the homogeneous cells is done using probabilities describing the chance that a neutron having a collision in one cell has its next collision in another cell. These collision probabilities can be cast in terms of escape and transmission probabilities for each cell. Some methods exist that extend the collision probability approach to systems composed of more than two homogeneous cells. In this work, we present a novel collision probability method, based on previous work by Schneider et al. (2006a), for an arbitrary number of cells. The method operates by averaging the transmission probabilities across cells of the same shape, and thus assumes a certain level of homogeneity across all cells. When using multigroup cross sections, which the collision probability approach requires, it is necessary to consider the effect that a system's geometry and composition has on those multigroup cross sections. The cross sections must be computed in a way that accounts for the resonance self-shielding that may reduce the reaction rates in the resonance region. The process of developing self-shielded cross sections in a heterogeneous system utilizes an escape cross section. We compute this escape cross section using the same collision probabilities used to obtain the energy spectrum. Results are presented for simple two-cell systems, and preliminary results for four-cell simulations are also given. An extension to the method is provided that accounts for the fact that in thermal systems the assumption of homogeneity is not always valid. / text
454

Neutron transmissions, capture yields, and resonance parameters in the energy range of 0.01 eV to 1 keV in rhenium

Epping, Brian Edward 18 March 2014 (has links)
The focus of this thesis is to improve upon the existing neutron cross section data for rhenium (Re) in the energy range 0.01 eV to 1 keV. Neutron transmission and capture yield measurements were performed using natural rhenium samples at the Rensselaer Polytechnic Institute Gaerttner Linear Accelerator Center. Measurements were performed using the time of flight method, in which neutron energies are differentiated using the elapsed times between neutron emission from a pulsed neutron source and the subsequent detector interactions. Transmission measurements were performed using ⁶Li glass scintillation detectors. Capture measurements were performed utilizing a 16-segment NaI(Tl) multiplicity detector. Most measurements were performed at a flight path length of 25 meters, with one set of experiments (thermal transmission) performed at 15 meters. The experiments used several metallic, elemental rhenium samples of various thicknesses, ranging from 1 mil to 100 mils. (1 mil = 0.001 inch = 0.0254 mm) Following the reduction of the experimental data, SAMMY was used to perform the data analysis. SAMMY is a shape-fitting Bayesian analysis code that determines resonance parameters by fitting neutron time of flight data using the Reich-Moore approximation of R-matrix theory. The combined transmission and capture yield data analysis determined resonance parameters for rhenium resonances in the energy range of 0.01 eV to 1 keV. The updated rhenium resonance parameters are compared to previously published parameters and ENDF/B-VII.1. / text
455

Measurement of the WZ Production Cross Section in Proton-Proton Collision at \(\sqrt s = 7 TeV\) and Limits on Anomalous Triple Gauge Couplings with the ATLAS Detector

Jeanty, Laura Elizabeth 28 August 2013 (has links)
In this dissertation, we present a study of WZ production in proton-proton collisions at a center-of-mass energy of 7 TeV. The data analyzed was collected by the ATLAS detector and corresponds to an integrated luminosity of \(4.6 fb^{−1}\) provided by the Large Hadron Collider in 2011. We select WZ events in the fully leptonic decay mode with electrons, muons, and missing transverse energy in the final state. Events are required to have three isolated leptons with significant transverse momentum, a large missing transverse energy, a Z candidate reconstructed from two of the selected leptons, and a W candidate reconstructed from the missing transverse energy and third lepton. The major backgrounds to the WZ signal in the leptonic decay channel are Z+jets events, ZZ production, Z+photon events, and events with top quarks. We estimate the Z+jets and top quark background contributions from data and take the expected contribution for the other background processes from simulation. We observe 317 WZ candidates in data, with a background expectation of \(68\pm10\) events. The total production cross section is extracted from the selected sample using a maximum likelihood method and is determined to be \(19.0^{+1.4}_{-1.3} (stat) \pm0.9 (syst) \pm0.4 (lumi) pb\), which is consistent with the next-to-leading Standard Model prediction of \(17.6^{+1.1}_{-1.0} pb\). WZ production in the Standard Model includes a contribution from the WWZ triple gauge boson vertex. If new physics beyond the Standard Model exists and interacts with W and Z bosons, the coupling of the WWZ vertex could differ from the Standard Model prediction. We set limits on anomalous triple gauge boson couplings using the transverse momentum spectrum of Z bosons in the selected sample. We derive the 95% confidence interval for three model-independent anomalous triple gauge couplings using a frequentist approach and set the most stringent bounds to date on two of the three parameters. / Physics
456

Measurement of the muon neutrino inclusive charged current cross section on iron using the MINOS detector

Loiacono, Laura Jean 07 January 2011 (has links)
The Neutrinos at the Main Injector (NuMI) facility at Fermi National Accelerator Laboratory (FNAL) produces an intense muon neutrino beam used by the Main Injector Neutrino Oscillation Search (MINOS), a neutrino oscillation experiment, and the Main INjector ExpeRiment [nu]-A, (MINER[nu]A), a neutrino interaction experiment. Absolute neutrino cross sections are determined via [mathematical equation], where the numerator is the measured number of neutrino interactions in the MINOS Detector and the denominator is the flux of incident neutrinos. Many past neutrino experiments have measured relative cross sections due to a lack of precise measurements of the incident neutrino flux, normalizing to better established reaction processes, such as quasielastic neutrino-nucleon scattering. But recent measurements of neutrino interactions on nuclear targets have brought to light questions about our understanding of nuclear effects in neutrino interactions. In this thesis the [nu subscript mu] inclusive charged current cross section on iron is measured using the MINOS Detector. The MINOS detector consists of alternating planes of steel and scintillator. The MINOS detector is optimized to measure muons produced in charged current [nu subscript mu] interactions. Along with muons, these interactions produce hadronic showers. The neutrino energy is measured from the total energy the particles deposit in the detector. The incident neutrino flux is measured using the muons produced alongside the neutrinos in meson decay. Three ionization chamber monitors located in the downstream portion of the NuMI beamline are used to measure the muon flux and thereby infer the neutrino flux by relation to the underlying pion and kaon meson flux. This thesis describes the muon flux instrumentation in the NuMI beam, its operation over the two year duration of this measurement, and the techniques used to derive the neutrino flux. / text
457

The San José project : mining, repression and resistance in Oaxaca

Williams, Edward Sansom 21 February 2011 (has links)
This report chronicles a conflict over a Canadian-owned silver and gold mine in San José del Progreso, Oaxaca, as told by the author’s first-hand experience, eyewitness interviews, and research. Beginning with the Mexican Federal Government’s concession of ejidal land for use by the mining company, without the consent or consultation of the surrounding population, elaboration of the Trinidad mine in San José del Progreso has resulted in division in the community and intense activism, sometimes resulting in violent conflict. / text
458

Gluon propagator in classical color field of colliding hadrons and its implications for hadronic cross sections

Cheung, Man-Fung 28 September 2011 (has links)
We review the Regge theory and the minijet model for pp and pp collisions. We show that, in the conventional minijet approach, the asymptotic behavior of the total cross section calculated using currently accepted gluon distribution function and perturbative QCD rises too rapidly when compared with the data and fails to satisfy Froissart bound. To tame the rise, we have developed a new formalism for the interaction between QCD gluon and the classical color field of the colliding nucleons, and show how the gluon propagator is modified. The corresponding gauge invariance condition of the propagator is derived and shown to be satisfied. The modified gluon propagator leads to a suppression of the minijet cross section due to the gg [rightwards arrow] gg sub-process in the small-x region. We show that the pp and pp total cross section from [square root]s = 5 GeV to 30 TeV can be described as a sum of a hard component contributed by the classical field modified minijet model and a soft component due to the exchange of the Pomeron and the I=0 exchange-degenerate [omega] and f Regge trajectories. The soft-component model is motivated by the notion of duality. The predicted total cross section has a ln s asymptotic behavior. / text
459

Βελτιστοποίηση σχεδιασμού πυλώνων ανεμογεννητριών σύμμικτης διατομής χάλυβα - σκυροδέματος

Λιβιτσάνος, Γεώργιος 02 June 2015 (has links)
Σκοπός είναι η διερεύνηση της τεχνολογίας των χερσαίων (onshore) ανεμογεννητριών και συγκεκριμένα των πυλώνων των ανεμογεννητριών. Αν εξετάσουμε το αιολικό δυναμικό στις χερσαίες περιοχές της Ευρώπης, παρατηρούμε αμέσως τις τεράστιες δυνατότητες ανάπτυξης ανεμογεννητριών. Παρατηρούμε επίσης την πλεονεκτική θέση της χώρας μας που εμφανίζεται να διαθέτει στο Αιγαίο πέλαγος μια από τις πλουσιότερες, σε αιολικό δυναμικό, περιοχές της Ευρώπης. Για να έχουμε όμως μεγαλύτερη απόδοση στην ισχύ μιας ανεμογεννήτριας πρέπει να αυξήσουμε το ύψος της έτσι ώστε να εκμεταλλευτούμε τις υψηλότερες ταχύτητες ανέμου σε μεγαλύτερα ύψη. Αυτό με την σειρά του θα επιφέρει πιο μεγάλα φορτία και επομένως μεγαλύτερες καταπονήσεις (εντατικά μεγέθη) στην βάση του πυλώνα καθώς η ανεμογεννήτρια προσομοιώνεται με σύστημα προβόλου. Ως συνέπεια τούτου θα πρέπει να αυξήσουμε την αντοχή του πυλώνα είτε αυξάνοντας το πάχος του υλικού της διατομής (αποφεύγεται – απαιτούνται μεγάλα πάχη συνεπώς μεγάλα κόστη), είτε αυξάνοντας τη διάμετρο της διατομής (αποφεύγεται – περιορισμένο πλάτος οδικού δικτύου που αποτρέπει την μεταφορά τμημάτων του πυλώνα της ανεμογεννήτριας με μεγάλες διατομές), είτε αυξάνοντας την αντοχή του υλικού της διατομής (αντικείμενο διατριβής). Στην παρούσα διατριβή γίνεται μελέτη βελτιστοποίησης σχεδιασμού των πυλώνων των ανεμογεννητριών με σύμμικτη διατομή χάλυβα-σκυροδέματος η οποία οδηγεί σε σχετικά μικρά πάχη διατομών, μικρής διαμέτρου, μεγάλης επιθυμητής αντοχής και μειωμένου κόστους υλικά. Αρχικά γίνεται η ανάλυση διατομής με στόχο την βελτιστοποίηση - ελαχιστοποίηση του κόστους για δεδομένη αντίσταση και στη συνέχεια η ανάλυση επαναλαμβάνεται για την βελτιστοποίηση του κόστους για δεδομένη δυσκαμψία. Στη συνέχεια με τη βοήθεια του σχεδιαστικού αναλυτικού προγράμματος ANSYS θα γίνει η σχεδίαση του πυλώνα της ανεμογεννήτριας όπου θα εφαρμοστούν τα προβλεπόμενα φορτία. Κατόπιν αυτού του σχεδιασμού διεξάγουμε πείραμα στο εργαστήριο όπου προσομοιώνουμε την ανεμογεννήτρια ώστε να συγκρίνουμε τα πειραματικά αποτελέσματα με την αναλυτική διαδικασία στο πρόγραμμα ANSYS. Γίνεται παράθεση και σχολιασμός των αποτελεσμάτων ώστε να προκύψουν τα συμπεράσματά μας και τελικώς γίνονται προτάσεις για περαιτέρω έρευνα όσον αφορά τα υλικά της διατομής των πυλώνων καθώς και την καλύτερη αξιοποίηση της αιολικής ενέργειας. / The aim is to investigate the technology of land (onshore) wind turbines and specifically for the pillars of wind turbines. If we investigate the wind potential in inland areas of Europe, we see immediately the enormous growth potential of wind turbines. We also observe the vantage point of our country that appears to have the Aegean Sea, one of the richest in wind potential areas of Europe. In order to increase the power of a wind turbine we must increase its height so as to take advantage of higher wind speeds at higher altitudes. This leads to higher loads and thus higher stresses (section forces) at the base of the tower as the wind turbine system is simulated with the cantilever system. As a consequence we should increase the strength of the pillar by increasing the thickness of the section material (to be avoided - large thicknesses therefore high costs required) or by increasing the diameter of the cross section (to be avoided - narrow road network that prevents transfer of the turbine pillar parts with large cross-sections), or by increasing the strength of the section’s material (subject of thesis). This thesis deal with the Design Optimization of Composite Cross Section Steel – Concrete Wind Turbine Towers which leads to relatively low thickness cross-sections, with small diameters, desirable high strength and reduced cost of materials. Initially we conduct sectional analysis in order to optimize - minimize the cost for a given resistance, and then the analysis is repeated for cost optimization for a given stiffness. Then we develop equations which correlate the moment, the stiffness and the cost of the wind turbine tower with the thicknesses of the materials (steel – concrete) which the cross section is composed of. Consequently we plot the equations that give the materials’ dimensions ranges when both the moment and stiffness is modified. Also we can understand how all this procedure affects the whole cost of the cross section. Then we conduct analysis and design of the wind turbine pillar with the analytical program ANSYS according to the design loads. Afterwards, lab-scale tests are conducted in order to model the wind turbine behavior. The experimental results are compared to the analytical observations. Finally we display and comment the results of that research so as to draw conclusions regarding the pillar design and the efficient wind energy utilization and present suggestions to future research.
460

Εκτόπιση νευτωνικών και μη νευτωνικών ρευστών από αγωγούς μεταβαλλόμενης διατομής

Δημακόπουλος, Ιωάννης Ε. 10 March 2009 (has links)
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