• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 63
  • 26
  • 17
  • 7
  • 5
  • 3
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 150
  • 32
  • 23
  • 21
  • 19
  • 18
  • 18
  • 16
  • 16
  • 15
  • 15
  • 15
  • 14
  • 13
  • 13
  • 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.
21

Improving the Nursing Practice Environment With Point of Care Specimen Collection

Saathoff, April Marie 01 January 2017 (has links)
Specimen collection and identification errors are a significant problem in healthcare, contributing to incorrect diagnoses, delayed care, lack of essential treatments, patient injury or death, increased length of stay and increased healthcare costs, and decreased patient satisfaction. The purpose of the project was to evaluate the implementation of specimen collection technology with barcode scanning and bedside label printing in the maternal child health division of a community teaching hospital. The project was driven from Donabedian's quality framework for healthcare implementations, indicating that evaluating the quality of health care can be drawn from the categories of structure, process, and outcomes. The project featured a quantitative analysis with a pretest-posttest design. Mislabeled specimen rates and collection turnaround times were generated from laboratory quality data and measured before, during, and after implementation of specimen collection technology. Data analysis using an independent samples t test in SPSS 17.0 compared the changes in the mean scores of specimen collection turnaround times and mislabeled specimen rates. Mislabeled specimen percentages in all areas decreased from 0.0250% preimplementation to 0.0023% postimplementation with a p value less than 0.001. Collection turnaround times greater than 60 minutes decreased following implementation of specimen collection technology by 22% with a p value less than 0.001. The implementation of specimen collection technology has positive implications for social change, including the expectation that as technology is proven to significantly improve the safety and quality of laboratory collections, there will be a mandate for implementation of safer collection processes in healthcare.
22

Criação de um biobanco institucional no Brasil: protocolos e padronização / Creation of an institutional biobank in Brazil: protocols and standardization

Zalaf, Bianca Rapini 11 March 2019 (has links)
Biobanco é definido como uma coleção organizada de material biológico humano e informações associadas, coletado e armazenado para fins de pesquisa, conforme regulamento, sob responsabilidade institucional, sem fins comerciais. Abordam ainda a saúde humana de uma maneira multidisciplinar, combinando a biologia e a medicina com tecnologias informativas de bioinformática e computação. Para um bom planejamento de um biobanco, deve-se ter conhecimento dos tipos de bioespécimes que serão armazenados, as condições necessárias de manuseio e armazenamento, bem como o período de permanência e possível aumento da quantidade de amostras. Por isso, este trabalho objetivou a criação de protocolos padrões para a elaboração de um Biobanco. Para isso, foram desenvolvidos protocolos específicos, os quais foram realizados de acordo o Guia de Boas Práticas, considerado o mais atual e de grande impacto, desenvolvido pela ISBER (Sociedade Internacional de Repositórios Biológicos e Ambientais). Também foram utilizadas a Portaria número 2.201, de 14 de setembro de 2011, a Resolução CNS 441 de 2011 e a Resolução RDC Nº 306, de 7 de Dezembro de 2004, todas do Ministério da Saúde. Os protocolos foram divididos em: 1) Informações Pessoais; 2) Bancos de Dados, 3) Coleta Geral de Amostras; 4) Quadro de Funcionários; 5) Instalações; 6) Segurança; 7) Leis e Ética; 8) Descarte de Materiais e 9) Elaboração da documentação para envio ao CONEP. Portanto, espera-se através deste trabalho, trazer as melhores práticas para a implementação e desenvolvimento de biobancos, visando melhorias na pesquisa e na ciência no quesito tecnológico e laboratorial, com base nos regulamentos éticos e legais. / Biobank is defined as an organized collection of human biological material and associated information, collected and stored for research purposes, according to regulation, under institutional responsibility, with no commercial purposes. It also addresses human health in a multidisciplinary way, combining biology and medicine with informative bioinformatics and computing technologies. For a suitable planning it must be aware of the types of biospecimens that will be stored, the appropriate conditions of handling and storage, as well as the period of permanence and possible increase of the quantity of samples. Therefore, this study aimed to the creation of standard protocols for the elaboration of a Biobank. For this, specific protocols have been developed, which were carried out according to the Best Practices Guide, considered the most updated and of great impact, such as the protocol developed by ISBER (International Society of Biological and Environmental Repositories). Also, was used an Administrative Order number 2.201, dated September 14, 2011, Resolution CNS 441 of 2011 and Resolution RDC No. 306, of December 7, 2004, all of the Ministry of Health. The protocols were divided into: 1) Personal Information; 2) Databases, 3) General Collection; 4) Staff Regulations; 5) Installation; 6) Security; 7) Laws and Ethics; 8) Materials Disposal and 9) Preparation of documentation for sending to CONEP. Therefore, it is expected through this work, to bring the best practices for implementation and development of biobanks, aiming for improvements in research and science regarding technological and laboratory aspects, based on ethical and legal regulations.
23

Automated Discovery of Pedigrees and Their Structures in Collections of STR DNA Specimens Using a Link Discovery Tool

Haun, Alex Brian 01 May 2010 (has links)
In instances of mass fatality, such as plane crashes, natural disasters, or terrorist attacks, investigators may encounter hundreds or thousands of DNA specimens representing victims. For example, during the January 2010 Haiti earthquake, entire communities were destroyed, resulting in the loss of thousands of lives. With such a large number of victims the discovery of family pedigrees is possible, but often requires the manual application of analytical methods, which are tedious, time-consuming, and expensive. The method presented in this thesis allows for automated pedigree discovery by extending Link Discovery Tool (LDT), a graph visualization tool designed for discovering linkages in large criminal networks. The proposed algorithm takes advantage of spatial clustering of graphs of DNA specimens to discover pedigree structures in large collections of specimens, saving both time and money in the identification process.
24

Crack lengths calculation by unloading compliance technique for Charpy size specimens

Dzugan, Jan 31 March 2010 (has links) (PDF)
The problems with the crack length determination by the unloading compliance method are well known for Charpy size specimens. The final crack lengths calculated for bent specimens do not fulfil ASTM 1820 accuracy requirements. Therefore some investigations have been performed to resolve this problem. In those studies it was considered that measured compliance should be corrected for various factors, but satisfying results were not attained. In the presented work the problem was attacked from the other side, the measured specimen compliance was taken as a correct value and what had to be adjusted was the calculation procedure. On the basis of experimentally obtained compliances of bent specimens and optically measured crack lengths the investigation was carried out. Finally, a calculation procedure enabling accurate crack length calculation up to 5mm of plastic deflection was developed. Applying the new procedure, out of investigated 238 measured crack lengths, more than 80% of the values fulfilled the ASTM 1820 accuracy requirements, while presently used procedure provided only about 30% of valid results. The newly proposed procedure can be also prospectively used in modified form for the specimens of different than Charpy size.
25

Automated Discovery of Pedigrees and Their Structures in Collections of STR DNA Specimens Using a Link Discovery Tool

Haun, Alex Brian 01 May 2010 (has links)
In instances of mass fatality, such as plane crashes, natural disasters, or terrorist attacks, investigators may encounter hundreds or thousands of DNA specimens representing victims. For example, during the January 2010 Haiti earthquake, entire communities were destroyed, resulting in the loss of thousands of lives. With such a large number of victims the discovery of family pedigrees is possible, but often requires the manual application of analytical methods, which are tedious, time-consuming, and expensive. The method presented in this thesis allows for automated pedigree discovery by extending Link Discovery Tool (LDT), a graph visualization tool designed for discovering linkages in large criminal networks. The proposed algorithm takes advantage of spatial clustering of graphs of DNA specimens to discover pedigree structures in large collections of specimens, saving both time and money in the identification process.
26

Effects of geometric and material property changes on the apparent elastic properties of cancellous bone

LIEVERS, WILLIAM BRENT 24 April 2009 (has links)
Osteoporosis is a disease characterized by reduced bone mass and reduced bone quality. This deterioration manifests itself in osteoporotic fractures at skeletal sites containing large proportions of cancellous bone (ie. forearm, hip, spine). Given the costs associated with these fractures, improvements in our ability to model and predict the behaviour of cancellous bone would be of great financial and social benefit to society. This thesis makes contributions in three areas within the much larger goal of developing a comprehensive model for describing the mechanical behaviour of cancellous bone. Since the accuracy of model predictions can only be as good as the test data against which it is compared, the effect of experimental artifacts introduced by specimen geometry is examined for cored samples. The apparent elastic modulus of cancellous bone is found to be relatively insensitive to specimen (or gauge) length, such that it can be reduced below the recommended 2:1 aspect ratio without introducing detectable artifact. Conversely, apparent modulus is found to be much more sensitive to specimen diameter. The role of water is also examined. Dehydration at room temperature was found to increase the apparent elastic modulus by roughly 14%. This net increase results from the competing effects of an increased tissue modulus and a decreased bone volume fraction due to shrinkage. Finally, preliminary work is presented which attempts to relate micro-CT voxel intensity and locally measured nanoindentation moduli, in order to provide an experimental basis for assigning heterogeneous material properties to finite element method (FEM) models. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-04-24 14:28:17.772
27

An Inverse Finite Element Analysis and A Parametric Study of Small Punch Tests

Xu, Zhenzhen 2011 December 1900 (has links)
Small punch test (SPT) has been widely used to evaluate in-service materials in nuclear fusion facilities. Early use of SPTs is largely based on empirical relations or curve fitting from experimental data, while recent applications of SPTs take advantage of finite element methods. In this study, an improved inverse finite element analysis procedure is proposed to obtain constitutive relations from load-displacement curves recorded in SPTs. In addition, a parametric study is performed to evaluate the effects of SPT parameters including friction coefficient, punch head diameter, sample thickness, specimen scale and boundary conditions. The proposed inverse finite element (FE) method improves the accuracy of existing inverse FE methods, and the current parametric study provides a basis for the standardization of SPT procedures in the future.
28

WTZ Russland - Fluenzberechnungen für Voreilproben beim WWER-440

Konheiser, Jörg, Grahn, Alexander 29 October 2014 (has links) (PDF)
Der Reaktordruckbehälter (RDB) zählt zu den nicht auswechselbaren Komponenten eines Kernkraftwerkes (KKW). Durch die hohen Neutronen- und Gammaflüsse ist er beschleunigten Alterungsprozessen unterworfen, welche die Lebensdauer eines KKW bestimmen könnten. So haben neben der chemischen Zusammensetzung des RDB-Stahls vor allem die Strahlungsparameter (Neutronen- und Gammafluenzen und deren Spektren) Auswirkungen auf die Versprödungseigenschaften des RDB. Für einen sicheren Betrieb eines KKW ist es daher sehr wichtig, die mögliche Änderung des Materialzustandes vom RDB im Voraus bewerten zu können. Die sogenannten Voreilprobenprogramme gehören deshalb zu den wichtigsten Überwachungsmaßnahmen im KKW. Mit ihnen kann die Restlebensdauer des RDB realistisch und zuverlässig beurteilt werden. In dieser Arbeit werden, neben der Bestimmung der Fluenzen an sich, auch Auswirkungen auf den Teilchenfluss in den Voreilproben, wie zum Beispiel die verschiedenen geometrischen Positionen, untersucht. Damit können mögliche Unsicherheiten bei der Bestimmung der realen Fluenzwerte abgeschätzt werden. Die Berechnungen wurden sowohl mit dem Code TRAMO als auch mit dem Code DORT durchgeführt. Die berechneten Ergebnisse wurden an Aktivierungsmonitoren, die an der RDBAußenoberfläche des KKW Kola, Unit 3 (WWER-440/213), bestrahlt wurden, überprüft. Hauptsächlich kamen Aktivierungsmonitore mit den Reaktionen 54Fe(n,p)54Mn und 58Ni(n,p)58Co zum Einsatz. Die Aktivitätsmessungen wurden vom russischen Partner, dem „Scientific and Engineering Centre for Nuclear and Radiation Safety“ (SEC NRS) durchgeführt. Es konnte gute Übereinstimmung sowohl zwischen den deterministischen und den stochastischen Berechnungsergebnissen als auch zwischen den berechneten und gemessenen Ergebnissen erzielt werden. Die durchschnittliche Differenz zwischen gemessenen und berechneten Werten betrug nur 5%. Ein Einfluss der Bestrahlungskanäle und der Versteifungsrippen der Kernumfassung auf die Monitoraktivität konnte festgestellt werden. Für die Voreilproben im Bereich des Flussmaximums wurden für den Neutronenfluss E> 0.5 MeV ein Mittelwert von rund 2.45*1012 Neutronen/cm2 berechnet. Dabei können die Unterschiede in Abhängigkeit von der Ausrichtung der Proben zum Reaktorkern bis zu 20% betragen. Abweichungen bis zu 10% können durch die Änderung der Position der Bestrahlungskapseln im Kanal entstehen. Auf Basis dieser Rechnungen wurden die Voreilfaktoren der Bestrahlungsproben bestimmt. Bei mittleren Zykluslängen würde die „End of Life“-Fluenz in den Bestrahlungsproben bereits nach 2 Jahren erreicht werden. Der berechnete maximale Gammafluss beträgt rund 3.4*1012 g/cm2s für E > 1.0 MeV und rund 8.4*1012 g/cm2s für E > 0.5 MeV, wobei der größte Anteil des Flusses (rund 97%) aus Neutronenreaktionen stammt. Damit sind die Gammaflüsse in den Proben zwei bis drei Mal so groß wie die der Neutronen. Trotzdem spielt die Materialschädigung durch die Gammastrahlung eine untergeordnete Rolle, da die DPAQuerschnitte (displacement per atom) von Gammas um etwa zwei bis drei Größenordnungen kleiner sind. Des Weiteren wurde untersucht, ob mögliche Ausheilprozesse durch zu hohe Temperaturen in den Bestrahlungsproben stattfinden könnten. Zu diesem Zweck wurde der Energieeintrag in den Bestrahlungsproben basierend auf den berechneten Teilchenflüssen bestimmt und mit einfachen thermohydraulischen Modellen die mögliche Aufheizung ermittelt. Eine Temperaturerhöhung von rund 20 K wurde mit einem konservativen Ansatz berechnet. Unter vergleichsweise realistischen Bedingungen reduzierte sich die Aufheizung auf unter 5 K. / Reactor pressure vessels (RPV) are non-restorable equipment and their lifetime may restrict the nuclear power plant-life as a whole. Surveillance specimen programs for RPV materials are among the most important measures of in-service inspection pro-grams that are necessary for realistic and reliable assessment of the RPV residual lifetime. In addition to the chemical composition of the RPV steel, the radiation pa-rameters (neutron and gamma fluences and spectra) have the most important impact on the RPV embrittlement characteristics. In this work, different geometric positions which have influence on the radiation conditions of the samples are investigated. Thus, the uncertainties can be determined in the fluence values of surveillance specimens. The fluence calculations were carried out by the codes TRAMO and DORT. This study was accompanied by ex-vessel neutron dosimetry experiments at Kola NPP, Unit 3 (VVER-440/213), which provide the basis for validation of calculated neutron fluences. The main neutron-activation monitoring reactions were 54Fe(n,p)54Mn and 58Ni(n,p)58Co. The activity measurements were carried out by “Scientific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS). Good agreement between the deterministic and stochastic calculation results as well as between the calculations and the ex-vessel measurements was found. The aver-age difference between measured and calculated values is 5%. The influence of the channels for surveillance specimens and the shielding effect of a baffle rib on the monitors and on the Monte-Carlo calculated results was studied. For the surveillance specimens in the maximum of the flux, an average flux of around 2.45 * 1012 neutrons/cm2 was calculated for the neutron flux E> 0.5 MeV. The differences in the surveillance specimens could be up to 20% depending on the direction to the core. Discrepancies up to 10% can be caused by the change of the position of the capsules in the irradiation channel. Based on these calculations the lead factor of specimens was determined. The maximum fluence of RPV may be achieved after two cycles. The calculated maximum gamma flux is around 3.4 * 1012 g/cm2s for E> 1.0 MeV and around 8.4 * 1012 g/cm2s for E> 0.5 MeV, with the largest part of the flux (around 97%) from the neutron reactions. The gamma fluxes in the surveillance specimens are two to three times bigger than the neutron fluxes. Nevertheless, the material damage by the gamma radiation is very small, because the dpa (displacement per atom) cross sections of gamma rays are about two to three orders of magnitude smaller. In order to exclude the possibility of healing effects of the samples due to excessive temperatures, the heat release in the surveillance specimens was determined based on the calculated gamma fluences. The analytic treatment of the heat conduction equation and simplified SS geometries were adopted to calculate the range of tem-peratures to be expected. The temperature increase of 20 K above the inlet coolant temperature was estimated using a conservative approach. Under comparatively re-alistic conditions, the heating was reduced to less than 5 K.
29

Deformation Analysis of Sand Specimens using 3D Digital Image Correlation for the Calibration of an Elasto-Plastic Model

Song, Ahran 2012 August 1900 (has links)
The use of Digital Image Correlation (DIC) technique has become increasingly popular for displacement measurements and for characterizing localized material deformation. In this study, a three-dimensional digital image correlation analysis (3D-DIC) was performed to investigate the displacements on the surface of isotropically consolidated and drained sand specimens during triaxial compression tests. The deformation of a representative volume of the material captured by 3D-DIC is used for the estimation of the kinematic and volumetric conditions of the specimen at different stages of deformation, combined with the readings of the global axial compression of the specimen. This allowed for the characterization of a Mohr-Coulomb plasticity model with hardening and softening laws. In addition, a two-dimensional axisymmetric finite element model was built to simulate the actual experimental conditions, including both the global and local kinematics effects captured by 3D digital image correlation analysis on the boundary of the specimen. A comparison between the axisymmetic model predictions and the experimental observations showed good agreement, for both the global and local behavior, in the case of different sand specimen configuration, including loose, dense and half-loose half-dense specimens.
30

Determination of Flow Stress and Coefficient of Friction for Extruded Anisotropic Materials under Cold Forming Conditions

Han, Han January 2002 (has links)
The work material in metal working operations always showssome kind of anisotropy. In order to simplify the theoreticalanalysis, especially considering bulk deformation processes,anisotropy is usually neglected and the material is assumed tobe isotropic. On the other hand, the analysis that consideredthe influence of anisotropy seldom incorporates the influenceof friction. For predicting the material flow during plasticdeformation and for predicting the final material properties ofthe product, adequate descriptions of both flow stress curvesand coefficients of friction have to be developed. In the present work a number of experimental methods fordetermining the anisotropy have been utilized and compared:Yield loci, strain ratios (R-values) and establishing flowstress-curves in different directions. The results show thatthe yield loci measurements are weak in predicting anisotropywhen the material strain hardening is different in differentdirections. It is concluded that also the strain ration(R-value) measurements are unreliable for describinganisotropy. The most trustable and useful results were foundfrom multi-direction determinations of the flow stresses. Three typical cases of ring upsetting conditions wereanalyzed by theory (3D-FEM) and experiments:     An anisotropic ring, oriented 900 to the axis ofrotational symmetrical anisotropy. The friction coefficientwas the same in all directions     An isotropic ring. The friction coefficient was differentin different directions     An anisotropic ring oriented 00 to the axis of rotationalsymmetrical anisotropy. The friction coefficient was the samein all directions The cases 1) and 2) reveal that the influence of anisotropyon the ring deformation is quite similar to that obtained bychanging the frictional condition. The case 3) exposes that ifthe material flow caused by anisotropy is incorrectly referredto friction, the possible error of the friction coefficient canbe as high as 80% for a pronounced anisotropic material. Amodified two-specimen method (MTSM) has been establishedaccording to an inverse method. Experiments were carried ascylinder upsetting. Here both ordinary cylinders were used aswell as so-called Rastegaev specimen. Also plane straincompression tests were utilized. The results show that MTSM isable to evaluate the validity of a selected mathematical modelwhen both the friction coefficient and the flow stress areunknown for a certain process. MTSM can also be used toestimate the friction coefficient and flow stress provided thatthe selected mathematical model is adequate. <b>Key words:</b>Anisotropy, friction coefficient, flowstress, modified two-specimen method and FE-analysis / NR 20140805

Page generated in 0.0452 seconds