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1
Yin, Ying. "Automatic defect localisation and classifiacation for X-ray weld images." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506501.
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Lu, Yicheng. "Real time defect detection in welds by ultrasonic means." Thesis, Brunel University, 1992. http://bura.brunel.ac.uk/handle/2438/4966.
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A computer controlled weld quality assurance system has been developed to detect weld defects ultrasonically whilst welding is in progress. This system, including a flash analogue to digital converter and built-in memories to store sampled data, a peak characters extractor and a welding process controller, enabled welding processes to be controlled automatically and welding defects to be detected concurrently with welding. In this way, the weld quality could be satisfactorily assured if no defect was detected and the welding cost was minimised either through avoiding similar defects to occur or by stopping the welding process if repair was necessary. This work demonstrated that the high temperature field around the weld pool was the major source of difficulties and unreliabilities in defect detection during welding and, had to be taken into account in welding control by ultrasonic means. The high temperatures not only influence ultrasonic characteristic parameters which are the defect judgement and assessment criterion, but also introduce noise into signals. The signal averaging technique and statistical analysis based on B-scan data have proved their feasibility to increase 'signal to noise ratio' effectively and to judge or assess weld defects. The hardware and the software for the system is explained in this work. By using this system, real-time 'A-scan' signals on screen display, and, A-scan, B-scan or three dimensional results can be printed on paper, or stored on disks, and, as a result, weld quality could be fully computerized.
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Xie, Lei [Verfasser]. "Study on relevant factors influencing the strength of weld line defect in micro injection molding process / Lei Xie." Clausthal-Zellerfeld : Universitätsbibliothek Clausthal, 2010. http://d-nb.info/1007800674/34.
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Zia, Tabari M. "Design, development and assessment of an automated ultrasonic inspection system in production and experimental analysis if tubular butt welds for identification and characterisation of weld defect." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376231.
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Kocak, Okan Okay. "Defect Assessment Of Spot Welds By Ndi." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1027382/index.pdf.
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Resistance spot welding is used frequently as a successful joining method for
a variety of work commonly in automotive and other manufacturing
processes. Spot weld nugget is generally hidden between two sheets,
causing its inspection difficult and expensive. Undersized nuggets, brittle or
cracked nuggets, and excessive indentation of electrodes reveals the lack of
fusion between the parts that can make the weld sub-standard.
Visual inspection, pry testing and physical teardown with chisel and hammer
method or a combination of them are being used traditionally. However, this
study presents a more effective nondestructive inspection method based
upon an ultrasonic pulse-echo technique. The theory of the technique together with the experimental verification are presented and its advantages over the other destructive and nondestructive
techniques are considered.
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Kountouris, Ioannis Savvas. "The assessment of weld defects in offshore structures." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47520.
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Lawson, Shaun W. "Automatic defect detection in industrial radioscopic and ultrasonic images." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/843944/.
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This thesis describes a number of approaches to the problems of automatic defect detection in ultrasonic Time of Flight Diffraction (TOFD) and X-ray radioscopic images of butt welds in steel plate. A number of novel image segmentation techniques are developed, two of which feature the use of backpropagation artificial neural networks. Two new methods for defect detection in ultrasonic TOFD images are described - the first uses thresholding of individual one-dimensional A-scans, and the second uses a neural network to classify pixels using two dimensional local area statistics. In addition, three new methods for defect detection in radioscopic images are described - the first is based on the use of two conventional spatial filters, the second uses grey level morphology to replace the 'blurring' stage of conventional "blur and subtract' procedures, and the third uses a neural network to classify pixels using raw grey level data at the input layer. It is considered that all five methods which have been developed show novelty in their methodology, design and implementation, most specifically in that (1) no previous methods for automatic defect detection in TOFD images, (2) very few successful implementations of grey level data processing by neural networks, and (3) few examples of local area segmentation of 'real' textured images for automatic inspection have been reported in the literature. The methods developed were tested against data interpreted by skilled NDT inspectors. In the case of the ultrasonic TOFD image processing, both automatic methods performed exceptionally well, producing results comparable to that of a human inspector. In the case of the radioscopic image processing, the ANN method also produced results comparable to that achieved by a human inspector and also gave comparable or consistently better results than those obtained using a number of existing techniques.
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Hollander, Jonathan Lee. "Defect-reduced growth and characterisation of off-basal III-nitride quantum well structures." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609372.
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Al-Ataby, Ali. "Automatic detection, sizing and characterisation of weld defects using ultrasonic time-of-flight diffraction." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/6413/.
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Ultrasonic time-of-flight diffraction (TOFD) is known as a reliable non-destructive testing technique for weld inspection in steel structures, providing accurate aw positioning and sizing. Despite all its good features, TOFD data interpretation and reporting are still performed manually by skilled inspectors and interpretation software operators. This is a cumbersome and error-prone process, leading to inevitable delay and inconsistency. The quality of the collected TOFD data is another issue that may introduce a host of error to the overall interpretation process. Manual interpretation focuses only on the compression waves portion of the collected TOFD data and overlooks the mode-converted waves region and considers it redundant. This region may provide useful and accurate aw sizing and classification information when there is uncertainty or ambiguity due to the nature of the collected data or the type of aw, and can reduce the number of supplementary (parallel) B-scans by utilising the (longitudinal) D-scans only. The automation of data processing in TOFD is required to minimise time and error and towards building a comprehensive computer-aided TOFD interpretation tool that can aid human operators. This project aims at proposing interpretation algorithms to size and characterise flaws automatically and accurately using data acquired from D-scans only. In order to achieve this, a number of novel data manipulation and processing techniques have been specifically developed and adapted to expose the information in the mode-converted waves region. In addition, several multi-resolution approaches employing the Wavelet transform and texture analysis have been used in aw detection and for de-noising and enhancing quality of the collected data. Performance of the developed algorithms and the results of their application have been promising in terms of speed, accuracy and consistency when compared to human interpretation by an expert operator, using the compression waves portion of the acquired data. This is expected to revolutionise the TOFD data interpretation and be in favour of a real-time processing of large volumes of data. It is highly anticipated that the research findings of this project will increase significantly the reliance on D-scans to obtain high sizing accuracy without the need to perform further B-scans. The overall inspection and interpretation time and cost will therefore be reduced significantly.
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Larsson, Anton, and Oliver Prytz. "Simulering av defekten “charge weld” analyserad mot verkligheten." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105275.
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Inom strängpressning av aluminium uppstår defekten charge weld vid byte av göt, då det gamla materialet sammanbinds med det nya. Denna defekt medför bland annat försämrad hållfasthet hos materialet. Med en ökad användning av aluminium i världen ökar även kvalitetskraven hos användarna. Defekten medför att en mängd aluminium måste skrotas och företag vill vara på den säkra sidan, därför kan mer än nödvändigt skrotas. Detta medför till en större mängd skrot och en större energianvändning då mer aluminium måste förbrukas och även smältas om. Företag har idag börjat använda sig av simulering för att ta fram den korrekta längden på profilerna som innehåller defekten charge weld. Men då simulering inom detta område är relativt nytt litar företag inte fullt ut på den då de inte vet om det är korrekt eller inte. Denna studie undersöker hur tillförlitlig simuleringen av charge weld är mot verkligheten samt ger en ökad förståelse för defekten som skall bidra till framtida utveckling. För att underlätta undersökningen av defekten på profiler genomfördes olika oförstörande provningsmetoder, för att detektera defektens längd. Det utfördes även kontroller över materialegenskaper med hjälp av dragprover. Studiens resultat säger att simuleringen inte är helt fullständig för att vissa profiler inte stämmer överens med verkligheten. Studien bekräftar även att defekten ger en försämrad hållfasthet. Den undersökning som gjordes med oförstörande provningsmetoder gav resultatet att materialet är massivt. OFP-metoder kan inte detektera defektens sammanbindning mellan gammalt och nytt göt.
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Cantin, G. M. Delphine. "An investigation of the formation of hollow bead defects in pipeline field welds /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phc231.pdf.
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Maher, David. "The relationship between defeat and entrapment and adolescent mental health and well-being." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30832/.
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Objective: Perceptions of defeat and entrapment are becoming increasingly important psychological constructs within research and clinical work that is focused on understanding the aetiology of mental health and promotion of well-being. Defeat and entrapment have been shown to be associated with depression, anxiety and suicidal behaviour within adult populations. Within the research literature, there is an ongoing debate as to whether defeat and entrapment should be considered as separate or single constructs. This study sought to bridge two gaps in the literature, by investigating the extent to which defeat and entrapment are associated with mental health and well-being measures within an adolescent non-clinical population and to which extent they are best conceptualised as separate or single constructs. Method: In total, 280 secondary school pupils aged 14 to 17 years old (M=14.83, SD=0.7) took part in this cross-sectional questionnaire-based study. Participants completed the study at their respective schools within North Lanarkshire Council, Scotland and participation remained anonymous. Participants completed the defeat and entrapment scale along with a variety of mental health and well-being measures including depression, anxiety, suicidal and self-harm thoughts and behaviour, frequency of alcohol and drug use, stress, self-esteem, optimism and overall life satisfaction. Results: Confirmatory factor analyses indicated that defeat and entrapment show a better fit with a two-factor model indicating that they are separate but highly related constructs. Female participants and those who previously attended mental health services had significantly higher defeat and entrapment scores. Multivariate hierarchical regression analyses reveal that perceptions of defeat were associated with anxiety, depression and stress symptomology and inversely associated with optimism, however these relationships were not significant after controlling for entrapment suggesting mediation. Entrapment was associated with depression, anxiety, deliberate self-harm ideation, stress and inversely associated with life satisfaction. Conclusion: This research has been novel in exploring the conceptual relationship of defeat and entrapment and adolescent mental health and well-being. Strengths, limitations and clinical implications are discussed.
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BUENO, SERGIO IBAJE OLIVEIRA. "STRUCTURAL ASSESSMENT OF PIPELINES WITH BLUNT CORROSION DEFECTS COINCIDENT WITH LONG-SEAM WELDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10728@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA redução de espessura de parede causada por corrosão é um dos defeitos que mais afetam a integridade dos dutos. Estes defeitos podem ocorrer no metal base, nas soldas longitudinais ou circunferenciais, bem como nas zonas afetadas pelo calor. Os métodos de avaliação da resistência remanescente introduzem ressalvas ou proíbem o tratamento de defeitos de corrosão coincidentes com as juntas soldadas. No presente trabalho foram avaliados os níveis de segurança dos métodos usuais de avaliação da resistência de dutos com defeitos introduzidos na região da solda longitudinal de tubos soldados por arco submerso. Os tubos testados eram de aço C-Mn fabricados na década de 60 e foram retirados de operação após uma campanha superior a 30 anos. Com estes tubos foram fabricados 5 espécimes, cada qual com 1 defeito externo produzido por eletro-erosão, sendo posteriormente submetidos a testes de pressão monitorados. Foram realizados ensaios de tração, ensaios de impacto Charpy e ensaios de dobramento, para determinação das propriedades mecânicas do metal de base, do metal de solda e da zona termicamente afetada (ZTA). Foram realizados também ensaios metalográficos do metal de base e do metal de solda, análise química do metal de base e do metal de solda e medição das tensões residuais no metal de solda. A aplicação dos métodos de nível 1 (ASME B31G, 085dL, RPA, DNV isolado e PCORRC) resultou em pressões previstas inferiores às pressões reais de ruptura para defeitos de formato esférico. Para defeitos de seção retangular a aplicação dos métodos de nível 1 resultou em pressões superiores às pressões reais. A aplicação dos métodos de nível 2 (Effective Area e DNV geometria complexa) resultou em pressões previstas superiores às pressões reais de ruptura para defeitos de formato esférico e de seção retangular. As análises das fraturas indicaram que não ocorreu falha por deficiência de tenacidade em nenhum espécime. A corrosão alveolar leve pré-existente na superfície interna dos espécimes foi apontada como causa mais provável das pressões previstas superiores às pressões reais de ruptura.
One of the most important issues that affects pipeline integrity is corrosion-caused metal loss. This type of defect can occur over the pipe body, seam or girth welds or even on heat affected zones. Pipeline remaining strength criterions are restricted or even prohibited for assessing corrosion defects coincident with weld regions. This present work investigated the reliability of the most common assessment criteria for corroded pipes when defects were coincident with seam weld region in submerged arc welded pipes. The tested specimens were C-Mn steel pipe, from a pipeline manufactured in the 60´s and had operated for over 30 years. Five external defects were created on five pipe specimens and pressure tested until rupture. Stress, charpy V-notch and bending tests were carried out to find the mechanical properties of the welded joints. Microstructure and chemical composition from base metal and weld metal were also analyzed. Residual stresses on welds were measured. The level 1 criterion (ASME B31G, 085dL, RPA, DNV single and PCORRC) applications have underestimated failure pressure for spherical shaped defects. On the other hand, the same criterions have overestimated failure pressure for rectangular shaped defects. The level 2 criterions (Effective Area e DNV complex geometry) application overestimated failure pressure for all 5 specimens with both spherical and rectangular shaped defects. Fracture analyses have indicated that no specimen had a toughness controlled failure. Internal pit corrosion that was found after pressure testing is recognized as the most probable cause of underestimated pressure forecasts.
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Henon-Vernet, Christine. "Contribution à l'étude métallurgique d'une liaison bimétallique soudée 16MND5/309/308." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0021.
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Les liaisons bimetalliques soudees concernees par cette etude interessent les assemblages par soudage des tubulures de cuve en acier faiblement allie 16mnd5 et des tuyauteries en acier austenitique 316 du circuit rep. Certaines de ces liaisons presentent en peau externe des defauts intergranulaires en premiere couche de beurrage qui n'apparaissent que lorsque la structure de cette premiere couche est purement austenitique. Les materiaux assembles ayant des coefficients de dilatation tres differents, nous avons suppose que la fatigue thermique pouvait etre responsable de la presence de ces defauts. Aussi, afin de tester cette hypothese et estimer le degre de nocivite de la structure austenitique, nous avons etudie une liaison bimetallique presentant une structure austenitique en premiere couche et avons simule la fatigue thermique par de la fatigue oligocyclique a 320c. Nous nous sommes attaches a decrire les transformations metallurgiques induites par le caractere heterogene de l'assemblage. De nombreuses discontinuites ont ainsi pu etre mises en evidence au niveau de l'interface metal de base/premiere couche de beurrage : discontinuites chimiques, microstructurales et cristallographiques. Une analyse des conditions de solidification imposees par le caractere heterogene de la liaison a ete proposee permettant de rendre compte des phenomenes observes. D'un point de vue mecanique, il semble que ces heterogeneites aient peu d'influence sur la tenue en fatigue de la liaison. Quel que soit le mode de sollicitation envisage, nous ne recreons pas les decohesions intergranulaires observees sur site. Une modelisation par elements finis a ete menee pour determiner la repartition de la deformation plastique cumulee et expliquer la presence d'une zone sans bandes de glissements apparentes au niveau de l'interface, cote beurrage.
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Letal, Gregory. "Integrated distributed feedback lasers and electroabsorption modulators fabricated using helium-plasma-assisted InP defect induced quantum well intermixing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/NQ66279.pdf.
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SILVA, LUCIANA FERREIRA. "3D IMAGE ACQUISITION, PROCESSING AND ANALYSIS: MICROCT AND FIB-SEM IN THE CHARACTERIZATION OF DEFECTS IN WET WELDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25051@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A caracterização tridimensional tem sido mais utilizada na área da ciência dos materiais devido à necessidade de melhor compreensão e resultados mais precisos acerca da microestrutura dos materiais, que não são completamente revelados pelas técnicas tradicionais de microscopia bidimensional. No presente trabalho dois tipos de técnicas de caracterização 3D foram utilizadas: MicroTC - Microtomografia de Raios-X (com tomógrafos de bancada e baseados em fonte síncrotron) e FIB-SEM (feixe de íons focalizados acoplados a um MEV). Estas técnicas foram aplicadas a um sistema específico: descontinuidades em metal de solda subaquática molhada. Estas descontinuidades (poros, trincas e inclusões) apresentam tamanhos típicos variando de nanômetros a dezenas de micrômetros. Além disso, apresentam formas, distribuição espacial e orientação bastante variada e complexa. Assim, esta tese apresenta o desenvolvimento de metodologia de aquisição, processamento, análise e visualização 3D de poros, trincas e inclusões em solda subaquática molhada, a partir de imagens obtidas por MicroTC e FIB-SEM. As técnicas de aquisição foram otimizadas para os diferentes tipos de descontinuidades. Rotinas especializadas de processamento e análise de imagens foram criadas, sempre que possível utilizando um ambiente de software livre (FIJI/ImageJ). Diversas medidas foram automaticamente obtidas: número de objetos, volume, fração volumétrica, área superficial, diâmetro de Feret, espessura, esfericidade e compacidade. Além disso, a construção de imagens 3D permitiu observar a forma e a distribuição espacial das descontinuidades presentes. Visando avaliar a sensibilidade para detecção de trincas por MicroTC, um corpo de prova com seção variável foi submetido a um ensaio de tração, de forma que as diferentes seções sofressem diferentes valores de tensão. Foi verificada uma correlação positiva entre o valor de tensão e o número, comprimento e espessura das trincas detectadas. Este experimento também revelou o impacto da resolução espacial e do ruído sobre a possibilidade de detectar as trincas de forma acurada.
3D characterization is growing quickly in materials science due to the demands of better microstructural characterization, which cannot be fully achieved with the traditional 2D microscopy techniques. In this work, two types of 3D characterization techniques were employed: MicroCT – microcomputed x-ray tomography (with both bench top and synchrotron sources) and FIB-SEM (focused ion beam coupled to SEM). These techniques were applied to a specific system: discontinuities in underwater wet welds. These discontinuities (pores, cracks and inclusions) range in size from nanometers to tens of microns. Moreover, they present complex and varied shapes, spatial distribution and orientation. Thus, this thesis presents the development of methodology for the acquisition, processing, analysis and visualization of pores, cracks and inclusions in underwater wet welds, from images obtained by MicroCT and FIB-SEM. The acquisition techniques and conditions were optimized for the different kinds of discontinuities. Specialized routines for image processing and analysis were developed, employing a free software environment whenever possible (FIJI/ImageJ). Several measurements were automatically obtained: number of objects, volume, volume fraction, surface area, feret diameter, thickness, sphericity and compacity. Moreover, the rendering of 3D images allowed the observation of the shape and spatial distribution of the discontinuities in the weld metal. To evaluate the detection sensitivity of cracks by MicroCT, a specimen with varied cross-sections was submitted to a tensile test, so that the different sections were submitted to to different stress values. A positive correlation was observed between the stress value and the number, length and thickness of the detected cracks. This experiment also showed the influence of spatial resolution and noise upon the possibility of detecting cracks accurately.
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Ferreira, Waydson Martins. "CaracterizaÃÃo de Defeitos de Soldagem atravÃs da AnÃlise Fractal de Sinais Ultra-SÃnicos Obtidos pela TÃcnica TOFD." Universidade Federal do CearÃ, 2004. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7344.
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AgÃncia Nacional do PetrÃleoO presente trabalho tem como objetivo caracterizar diferentes defeitos de soldagem ( falta de fusÃo, falta de penetraÃÃo e porosidade) inseridos em corpos de prova durante o processo de soldagem, atravÃs da anÃlise fractal di sinais ultra-sÃnicos obtidos pela tÃcnica TOFD. Para eliminar os ruÃdos, os sinais foram tratados usando dois mÃtodos de filtragem, passa banda e Savitzky-Golay. Na anÃlise fractal dos sinais foram utilizados trÃs mÃtodos: anÃlise de Hurst, anÃlise de flutuaÃÃo sem tendÃncias e anÃlise de cobertura mÃnima. Nos trÃs mÃtodos foram considerados sinais filtrados isoladamente, bem como sinais filtrados concatenados. Os parÃmetros caracterÃsticos das regiÃes de escala, para cada tipo de anÃlise, foram calculados atravÃs de regressÃes lineares, sendo tambÃm determinado o desvio padrÃo de cada sinal. A caracterizaÃÃo de todos os defeitos foi determinada atravÃs dos parÃmetros obtidos para os sinais filtrados pelo mÃtodo Savitzky-Golay e para os sinais concatenados filtrados pelo mÃtodo passa banda. Foi tambÃm mostrado que, no contexto dessa anÃlise fractal, a melhor discriminaÃÃo foi obtida utilizando o mÃtodo de Savitzky-Golay.
The present work aims to characterize different welding defects (lack of fusion, lack of penetration and porosity) inserted into the specimens during the welding process by analyzing fractal di ultrasonic signals obtained by the TOFD technique. To eliminate the noise, the signals were processed using two methods of filtering, band pass and Savitzky-Golay. In fractal analysis of signals using three methods: analysis of Hurst analysis, trends and fluctuation analysis without minimum coverage. In the three methods were individually filtered signals and filtered signals concatenated. The characteristic parameters of the regions of scale, for each type of analysis were calculated by linear regression, and is also given the standard deviation of each signal. The characterization of all defects was determined by the parameters obtained for the signals filtered by the method Savitzky-Golay and concatenated signals filtered by bandpass method. It was also shown that in the context of this fractal analysis, the best discrimination was achieved using the method Savitzky-Golay.
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Tang, Lisa Choy. "Psychological well-being in parents of children with pervasive developmental disorders and attention-deficit / hyperactivity disorder." Diss., Connect to online resource - MSU authorized users, 2008.
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Dauskurdis, Kęstutis. "R65 tipo bėgio kontaktinio suvirinimo jungties tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140619_144302-31757.
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Šiame baigiamajame magistro darbe tiriama R65 tipo bėgio kontaktinio suvirinimo jungtis. Supažindinama su pagrindiniais mokslininkų parašytais straipsniais, bėgių kontaktinio suvirinimo tematika. Pateikiama tyrimų metodika, kurią sudaro šios dalys: apžiūrimasis paviršiaus tyrimas, ultragarsinės kontrolės tyrimas, važiuojamasis paviršiaus kiečio bandymas, sulydimo zonos nustatymas, termiškai suminkštintos zonos kiečio matavimas, mikrokietumo matavimas, mikroskopinis jungties matomosios terminio poveikio ir sulydymo zonų tyrimas, smūginio tąsumo bandymas, cheminė analizė, aširačio bandažo ir bėgio sąveikos tyrimas baigtinių elementų metodu (BEM). Išanalizuoti gauti tyrimo rezultatai, kurie įvertina suvirinimo siūlės kokybę. Pateiktos tiriamojo darbo išvados.In the final thesis of masters degree I analyze the R65 type rail joint that were welded flash butt. Introducing with scientific articles about flash butt welding of rails. Survey methodology of the research, which consists of the following parts: visual surface review of welded joint, ultrasonic rail inspection, hardness test of upper part of the rail, fusion area research, the measurement test hardness of heat-softened area, the measurement test microhardness, microstructure research of the welded joint, impact strenght experiments, chemical analysis of welded joint, wheel-rail interaction research of the finite element method (FEM). Analyzes the results of the research, who assess the quality of weld. The conclusion is based on the results of this research.
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Tesser, Juliano Accioly. "CaracterizaÃÃo de Defeitos de Soldagem por AnÃlise Fractal Utilizando EmissÃo AcÃstica em Ensaios de TraÃÃo." Universidade Federal do CearÃ, 2004. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7329.
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O presente trabalho tem como objetivo caracterizar e correlacionar formas de onda de sinais de emissÃo acÃstica, utilizando mÃtodos de anÃlise espectral e fractal, em corpos de prova previamente soldados com seus respectivos defeitos, avaliando assim a integridade estrutural do material aÃo carbono ASTM 516 Grau 60, utilizado em vasos de pressÃo, tubulaÃÃes, esferas de armazenamento, etc. Os sinais de emissÃo acÃstica foram gerados submetendo os corpos de prova a ensaios de traÃÃo. Para anÃlise dos sinais no domÃnio dos tempos, foram utilizados o mÃtodo de contagem de caixas, que fornece a dimensÃo fractal, e o de intervalo re-escalado de Hurst, e no domÃnio das freqÃÃncias o mÃtodo espectral de Fourier. AtravÃs das relaÃÃes previstas pelas leis de escala, concluiu-se que os expoentes calculados pelos mÃtodos espectral de Fourier e reescalado de Hurst, correlacionam-se entre si, bem como com a dimensÃo fractal obtida pelo mÃtodo de contagem de caixas. Mostrou-se tambÃm a existÃncia de duas regiÃes de escala distintas que caracterizam a mudanÃa do regime elÃstico para o regime plÃstico quando as amostras foram submetidas ao carregamento de traÃÃo. Verificou-se ainda que este comporta-mento foi caracterÃstico tanto para os materiais soldados como para o metal de base.The present work aims to characterize and correlate waveforms of acoustic emission signals, using methods of spectral analysis and fractal in specimens previously soldiers with their defects, thus evaluating the structural integrity of the material carbon steel ASTM 516 Grade 60 used in pressure vessels, piping, storage spheres, etc.. The acoustic emission signals were generated by subjecting the specimens to tensile tests. For analysis of the signals in the time domain, we used the method of box counting, which provides the fractal dimension, and re-scaled range of Hurst, and in the frequency domain the Fourier spectral method. Through the relations laid down by law scale, it was concluded that the exponents calculated by Fourier transform and spectral methods reescalado Hurst, are correlated with each other as well as the fractal dimension obtained from a box counting. It was also shown existence of two regions of different scale characterizing the change of the elastic to the plastic regime when the samples were subjected to traction. It was further found that this behavior is characteristic for both the welded material as for the parent metal.
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Heckel, Leila D. "The relationship between parental divorce and the psychological well-being of children with AD/HD differences in subtypes, age, gender and comorbidity /." Access electronically, 2007. http://ro.uow.edu.au/theses/10.
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Měřičková, Petra. "Svařování rámu výtahové kabiny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231112.
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Stress relieving in the welded joints occurs when loaded of the platform lift. Critical welds of profile from steel S235JRH and of stiffener from steel S355J0 are examined in terms of flexibility, strength and safety using strength analysis method. Under different welding conditions and parameters are performed the testing welds by method MAG. Macroscopic and microscopic inspection are conducted as well as tension test. Weld created in active gas 82 %Ar + 18 %CO2, by dip transfer with low values of welding current 96 A and voltage 20,2 V became as the top evaluated sample. This weld is recommended to use in practice.
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Björling, Linnéa, and Gardell Alicia Diaz. "Reparation av inbyggda stålbalkar : Ekonomiska och tidseffektiva förstärkningsmetoder med låg klimatpåverkan." Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259636.
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CE-märkta stålbalkar byggdes in i två konstruktioner innan det upptäcktes att det fanns porer i hattbalkarnas svets. Den defekta svetsen innebar att byggnadernas bärförmåga inte kunde garanteras. Kunskapen kring inbyggt stål stommaterial med defekt svets är liten. Det är dessutom svårt att reparera och undersöka stålbalkarnas svets när de är inbyggda i konstruktionen. Syftet med examensarbetet är att hitta förstärkningsmetoder och därmed främja kortare hanteringstid vid händelse av att defekta stålbalkar byggs in i en konstruktion. Metoden består av litteraturstudie och intervjuer. Först granskas litteratur för att förstå problematiken med defekt svets i stål stommaterial. Därefter utförs intervjuer med personer erfarna inom stål och byggteknik. Examensarbetets resultat är ett flertal förstärkningsmetoder för inbyggda stålbalkar med defekt svets. Några av förstärkningsmetoderna är möjliga att utföra med den kunskap som finns idag medan andra behöver undersökas och värderas innan de kan implementeras. Förstärkningsmetoderna som är möjliga att utföra med dagens kunskap är: att svetsa om balken från insidan eller att placera en balk/fackverksbalk under den befintliga balken. De metoder som behöver undersökas och värderas vidare är: skruvförband genom balken, efterspänna balken med vajrar eller GWS-stag och sedan fylla den med betong, föra in en balk inne i balken och fylla balken med betong och att kolfiberförstärka svetsen. Slutsatsen är att den här studien kan ligga till grund för framtagning av åtgärder för inbyggda stålbalkar med defekt svets med mål att uppnå den dimensionerade hållfastheten och en lösning som är tidseffektiv, kostnadseffektiv och har låg klimatpåverkan.Before the discovery of pores in the weld, CE-certified steel beams were embedded in two constructions. Since the weld was defective, the carrying capacity of the two buildings was questioned. There is a lack of knowledge about embedded steel beams with a damaged weld. It is difficult to repair and analyze the weld when the beams are embedded in the construction. The aim of the study is to find reinforcement methods for steel beams. The expectation is to shorten time in the production in case that defective steel beams are detected in the construction. The method consists of a literature study complemented by interviews. Literature is examined to understand the problem of defective welding in the steel framework. Subsequently, interviews are conducted with professionals within steel and building technology. The result of the report is multiple reinforcement methods for embedded steel beams with a defective weld. Some of the methods are possible to implement with the knowledge available today. Other methods need to be examined and assessed before executed. The reinforcement methods that are possible to perform are: weld the beam from the inside or place a beam underneath the existing beam. The methods that need further analysis are: drill a screw joint through the beam, strain the beam with steel-wires and fill the inside with concrete, place a beam inside the existing beam and fill the inside with concrete and last to reinforce the weld with carbon fibers. The conclusion is that this study can be used when reinforcement methods are needed for embedded steel beams with a defective weld. The objective with these methods is to restore the load-bearing capacity as well as finding a solution that is time efficient, economic and has low climatic influence.
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Davies, Matthew John. "Optical studies of InGaN/GaN quantum well structures." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/optical-studies-of-ingangan-quantum-well-structures(f6c6e59b-8366-44aa-b149-9338d3f03dc0).html.
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In this thesis I present and discuss the results of optical spectroscopy performed on InGaN/GaN single and multiple quantum well (QW) structures. I report on the optical properties of InGaN/GaN single and multiple QW structures, measured at high excitation power densities. I show a correlation exists between the reduction in PL efficiency at high excitation power densities, the phenomenon so-called ``efficiency-droop'', and a broadening of the PL spectra. I also show a distinct change in recombination dynamics, measured by time-resolved photoluminescence (PL), which occurs at the excitation power densities for which efficiency droop is measured. The broadening of the PL spectra at high excitation power densities is shown to occur due to a rapidly redshifting, short-lived high energy emission band. The high energy emission band is proposed to be due to the recombination of weakly localised/delocalised carriers occurring as a consequence of the progressive saturation of the local potential fluctuations responsible for carrier localisation, at high excitation power densities. I report on the effects of varying threading dislocation (TD) density on the optical properties of InGaN/GaN multiple QW structures. No systematic relationship exists between the room temperature internal quantum efficiency (IQE) and the TD density, in a series of nominally identical InGaN/GaN multiple QWs deposited on GaN templates of varying TD density. I also show the excitation power density dependence of the PL efficiency, at room temperatures, is unaffected for variation in the TD density between 2 x107 and 5 x109 cm-2. The independence of the optical properties to TD density is proposed to be a consequence of the strong carrier localisation, and hence short carrier diffusion lengths. I report on the effects of including an InGaN underlayer on the optical and microstructural properties of InGaN/GaN multiple QW structures. I show an increase in the room temperature IQE occurs for the structure containing the InGaN underlayer, compared to the reference. I show using PL excitation spectroscopy that an additional carrier transfer and recombination process occurs on the high energy side of the PL spectrum associated with the InGaN underlayer. Using PL decay time measurements I show the additional recombination process for carriers excited in the underlayer occurs on a faster timescale than the recombination at the peak of the PL spectrum. The additional contribution to the spectrum from the faster recombination process is proposed as responsible for the increase in room temperature IQE.
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Panori, Sheila Ann. "The effect of attention-deficit hyperactivity symptoms on well-being in college students: Implications for academic achievement and retention." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/1334.
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Zíka, Luboš. "Lokalizace vad svarů jeřábů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230002.
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The diploma thesis deals with the problematics of weld defects of cranes localisation and check. The aim is to analyse non-destructive methods, monitor the occurence of defects and their form and also to suggest the procedure of correction. The work is divided into a theoretical and practical part. In the theoretical part, there is an analysis of individual methods of non-destructive testing that are used for weld check on a particular girder. There is also an analysis of welding technologies used when making a crane girder. The practical part deals with evaluation of weld defects using two methods of non-destructive testing. Furthermore, statistics of defects is realised. In conclusion, the statistics outcome is resumed and evaluated.
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Börner, Michaela. "Real and illusory reports of posttraumatic growth and their correlation with well-being : an empirical examination with special focus on defence mechanisms." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38528/.
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Reports of posttraumatic growth can sometimes be illusory. Several researchers have argued that reports of posttraumatic growth may incorporate two separate phenomena, namely real posttraumatic growth and illusory posttraumatic growth. However, it is not often made explicit which kinds of illusions indicate illusory posttraumatic growth. An explicit conceptualisation of illusory posttraumatic growth is, however, necessary in order to investigate the research questions within this thesis, namely (a) whether reports of posttraumatic growth are correlated with illusions and (b) whether real posttraumatic growth and illusory posttraumatic growth differ in their correlation with well-being. Within the thesis, it was, therefore, primarily suggested that defensiveness could be responsible for illusory posttraumatic growth. The assumption was that high levels of maladaptive defensiveness may be used when distress cannot be endured. Internal and external experiences could then be pushed away. This case could potentially indicate illusory posttraumatic growth. In contrast, people who use low levels of maladaptive defences or high levels of mature defences may be able to endure the distress following a trauma or adversity. Internal and external experiences may be processed and accommodated. This case could potentially indicate real posttraumatic growth. The assumptions about illusions were tested within the thesis. It was investigated which kind of illusions could be adaptive psychological operations and which illusions could be maladaptive psychological operations. The results supported the assumptions within this thesis concerning adaptive versus maladaptive illusions. Within three studies, self-reported posttraumatic growth was significantly correlated with a neurotic defence style. It was concluded that this correlation could indicate that sometimes reports of posttraumatic growth are not real. However, other interpretations were also discussed. Four studies investigated whether real posttraumatic growth and illusory posttraumatic growth differ in their correlation with well-being. Within chapter 5, real posttraumatic growth, indicated by low levels of a neurotic or an immature defence style, was correlated positively with negative change following adversity (non significant). In contrast, illusory posttraumatic growth, indicated by high levels of a neurotic or an immature defence style, was not correlated with negative change following adversity. Although the difference between illusory posttraumatic growth and real posttraumatic growth concerning negative change following adversity had a meaningful effect size, it was not significant. Within chapter 7.3, real posttraumatic growth, indicated by extremely low levels of neurotic defensiveness, was correlated significantly with posttraumatic stress. In contrast, illusory posttraumatic growth, indicated by extremely high levels of neurotic defensiveness, was not correlated with posttraumatic stress. The difference between real posttraumatic growth and illusory posttraumatic growth was significant. Within chapter 8, real posttraumatic growth (high levels of mature defensiveness) was correlated with decreases in hedonic well-being measured by positive and negative affect. In contrast, illusory posttraumatic growth (low levels of mature defensiveness) was correlated with increased levels of hedonic well-being. The difference between real posttraumatic growth and illusory posttraumatic growth was significant. In total, reports of posttraumatic growth may, in fact, sometimes be correlated with defensiveness. However, real posttraumatic growth and illusory posttraumatic growth do only slightly differ concerning their correlation with well-being.
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Bürger, Steven, and Bernd Hofmann. "About a deficit in low order convergence rates on the example of autoconvolution." Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-130630.
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We revisit in L2-spaces the autoconvolution equation x ∗ x = y with solutions which are real-valued or complex-valued functions x(t) defined on a finite real interval, say t ∈ [0,1]. Such operator equations of quadratic type occur in physics of spectra, in optics and in stochastics, often as part of a more complex task. Because of their weak nonlinearity deautoconvolution problems are not seen as difficult and hence little attention is paid to them wrongly. In this paper, we will indicate on the example of autoconvolution a deficit in low order convergence rates for regularized solutions of nonlinear ill-posed operator equations F(x)=y with solutions x† in a Hilbert space setting. So for the real-valued version of the deautoconvolution problem, which is locally ill-posed everywhere, the classical convergence rate theory developed for the Tikhonov regularization of nonlinear ill-posed problems reaches its limits if standard source conditions using the range of F (x† )∗ fail. On the other hand, convergence rate results based on Hölder source conditions with small Hölder exponent and logarithmic source conditions or on the method of approximate source conditions are not applicable since qualified nonlinearity conditions are required which cannot be shown for the autoconvolution case according to current knowledge. We also discuss the complex-valued version of autoconvolution with full data on [0,2] and see that ill-posedness must be expected if unbounded amplitude functions are admissible. As a new detail, we present situations of local well-posedness if the domain of the autoconvolution operator is restricted to complex L2-functions with a fixed and uniformly bounded modulus function.
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Prayag, Kervin D. "The effects of elevated [CO₂] and decreased vapour pressure deficit on the nutrient status of maize and wheat plants under well-watered conditions." Master's thesis, University of Cape Town, 2020. http://hdl.handle.net/11427/32525.
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Increases in photosynthetic rates (A), biomass production and grain yield have been measured across a range of C₃ plants under elevated atmospheric [CO₂] ('eCO₂'). However, decreases in the nutritional status of many C₃ plants growing at eCO₂ often occur concurrently with these increases. Several mechanisms have been proposed for these eCO₂-induced decreases, such as dilution effects due to enhanced carbohydrate production, down-regulation of photosynthesis, reduced root development, and decreased transpiration-driven mass flow delivery of nutrients. Reduced mass flow at eCO₂ is generally accepted as one cause for altered nutrient status in C₃ plants. However, eCO₂-induced reductions in mass flow remain understudied in C₄ plants, even though they account for about 18% of the total global net primary productivity and represent a large food source globally (e.g. maize and sorghum). This thesis investigated how mass flow reductions affect the nutrient status of wheat (C₃) and maize (C₄) plants. Reduced mass flow in both maize and wheat plants was induced with eCO₂ and by varying leaf-to-air vapour pressure deficits (VPD). I hypothesised that reduced mass flow at eCO₂ and at low VPD will negatively affect nutrient status in both the C₃ (wheat) and the C₄ (maize) species. In the first experiment, maize and wheat plants were grown at 400 and 800 ppm [CO₂], in three well-watered soils, ranging from sandy to clayey, with and without fertilisation. In the second experiment, plants were grown at three VPD levels, namely 1.613 kPa, 0.773 kPa and 0.350 kPa, in well-watered soil and sand. In the latter experiment, to demonstrate the importance of mass flow, plants grown in sand were supplied nutrients in such a way that they had to rely exclusively on mass flow or diffusive processes (i.e. limited interception) for nutrient delivery to their rhizosphere. eCO₂ stimulated A on average by 22% in maize and by 50% in wheat, while stomatal conductance (ɡₛ) and cumulative water loss (CWL) were respectively decreased by 35% and 31% in maize, and by 26% and 37% in wheat. eCO₂ reduced mass flow delivery of most nutrients on average by 32% in maize, and by 38% in wheat. The hypothesis that eCO₂-induced reductions in mass flow negatively affect nutrient status in maize 33 and wheat was however not supported. This was attributed to the well-watered conditions of the soils, which may have allowed for other processes (e.g. diffusion) to make up for the mass flow reductions. From 0.773 kPa to 0.350 kPa VPD, CWL was decreased on average by 14% and 20% in the maize and wheat plants, respectively. A and ɡₛ were little affected by VPD, but plants of both species always accumulated more biomass at 0.773 kPa. Consequently, there was little evidence to suggest that VPD-induced reductions in mass flow negatively affect nutrient status in maize and wheat. Reduced CWL may have impeded root-to-shoot transport of ions and reduced dry biomass accumulation in the maize and wheat plants at 0.350 kPa (-40% and -22% on average respectively, relative to 0.773 kPa plants). Tissue [NPK] was also decreased (-13%, -41% and -47% respectively) in the 0.350 kPa VPD sand wheat plants, while increases in the proportion of finer roots may have alleviated effects of reduced CWL on tissue [NPK] in the C₄ species. The findings from both experiments imply a decrease in the importance of mass flow for the delivery of nutrients to the rhizosphere under well-watered conditions. However, reductions in mass flow to a similar extent in both species at eCO₂ and low VPD - measured in the present study - suggest that under conditions of low water and nutrient availability, tissue nutrient concentrations could be negatively affected when transpiration is reduced.
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Bona, Melissa Ellen. "The effect of straightening and grinding of welds on track roughness." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16180/.
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Rail is a very expensive component of the railway track. Therefore, research methods extending rail life have great economic importance. During the past thirty years and, particularly during the past ten years there has been an increasing awareness throughout most rail networks in the world of the need to introduce improved design criteria, better construction techniques and higher standard track generally. This implies that quality control at all levels is mandatory if these objectives are to be achieved. With the improved understanding of degradation of track, a more complete comprehension of the costs associated with different operating and infrastructure conditions should also be developed, aiding in the determination of efficient maintenance costs and their contribution to access charges. Track and structures together account for 60% of maintenance costs, with 50% of the total being track. The UIC has done a lot of work on comparative performance indicators, and these show what potential savings much be out there for the taking, just by adopting current best practice. The old wisdom is that it's not enough o do things rights; we have to make sure that we do the right things. These developments have largely resulted from the demand for higher speeds particularly in passenger services and the demand to accept heavier axle loads of freight traffic. Whilst the conventional railway track structure is not likely to change significantly over the next ten years there will be a requirement over that period for better quality track infrastructure. This means less rail surface defects, less internal defects and less wheels irregularities. The presence of rail surface defects generally increases the roughness of the track leading to a poor passenger ride and increased safety risk with freight traffic. In addition, rail surface defects will generally increase the degradation rate of other track components; however, not all defects will produce visible track deterioration. Dynamic impacts produced by the rollingstock running over rail surface defects, such as poor welds, will, over time, create continuous rail defects, loosening of fastenings, abrasion and skewing of sleepers, crushing of ballast and loss of formation geometry. It is only in the recent years that the importance of poor welds in track has been identified. Dips and peaks must be recognised as a severe track irregularity that needs to be addressed and removed. Current maintenance activities have little effect on removing misaligned welds in track and the improvement obtained after the maintenance works is generally short lived. On the other hand, straightening operations have proven to solve the problem and maintain the results following 7 months of traffic. As part of this project, a six kilometre test section was selected on the Mt Isa Line and all welds located in this region were monitored for over 9 months to increase the understanding of the effect of individual maintenance activities on the track roughness. Three 2km Divisions were established; each Division had different maintenance activities and levels of intervention completed over the duration of the project. Over 15,000 readings were recorded and analysed. The following conclusions were drawn. The effect of cycle tamping was clearly identified when comparing the means of weld located in Division 1, 2 to the mean of welds in Division 3. Cycle tamping showed to have a significant positive effect on the dipped welds geometry and an increase in severity of peaked welds prior to their correction. Straightening operations completed in Division 1 and 2 reduced the overall mean of weld misalignments. These Divisions were subjected to different levels of straightening intervention however they produced similar results. Division 1 all dips were straightened and Division 2 only dips >0.3mm were straightened. This means that no additional benefit, in terms of overall misalignment of welds, can be gained when straightening operations target dips with a misalignment smaller than 0.3mm. Cycle grinding proved to have little effect on the removal of both dips and peaks. In fact, due to the configuration of the grinding machine, grinding operation produced a slight worsening of the dips misalignments and only a minor improvement of peaks. Although long term monitoring of the site may show minor variations in weld geometry performance, after approximately 3.9 Mgt of traffic the mean of dipped welds in Division 1 and 2 appeared to remain unaltered, as Division 3 showed a minor worsening. Furthermore, the mean of peaked welds in Division 1 and 2 appeared to remain unaltered, as Division 3 showed a minor worsening.
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Vu, Duy Hoang [Verfasser], and Folkard [Akademischer Betreuer] Asch. "Effects of temperature and vapor pressure deficit on genotypic responses to nitrogen nutrition and weed competition in lowland rice / Duy Hoang Vu ; Betreuer: Folkard Asch." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2021. http://d-nb.info/1240761198/34.
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Dolejský, Tomáš. "Porovnání nákladů na svařování a Virtual Welding." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231042.
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The thesis deals with a potential application of welding simulators in basic courses of welding held in welding schools. The first section briefly describes the welding simulators in the global market. There is a detailed description and the control of the welding simulator Virtual Welding, a description of core courses of welding and the necessary welding technology in the following section. Experiments with a welding simulator are carried out in the last section and also their evaluation, comparison and summary of costs.
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Barsoum, Zuheir. "Residual Stress Analysis and Fatigue Assessment of Welded Steel Structures." Doctoral thesis, Stockholm : Farkost och flyg, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4687.
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Brehovský, Patrik. "Svařování hlubokotažných ocelí s ochrannou vrstvou hybridní technologií Laser-TIG." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417119.
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The diploma thesis focuses on laser welding of extra deep-drawn steel sheet according to the standard WSS-M1A365-A14 with a protective zinc surface layer. A 0,9 mm thick steel sheet with a zinc layer with coating weight 50 g · m^-2 is welded by a hybrid welding method Laser-TIG. The laser, as the primary energy source, is used for welding the material. The arc, provided by a non-melting tungsten electrode, is used for preheating the material for melting and evaporation of the zinc layer. Based on the initial experiments, the magnitude of the laser power with the welding speed was chosen as a constant parameter. The magnitude of the electric current, as the variable parameter, was set up to 0, 20, 30 and 40 ampers for welding the lap and the butt welds. Only one piece of the each weld type combination was made. The welds were afterwards tested to verify their quality and material properties. The first differences between laser welding with or without TIG preheating were visible during the experiment. The positive effects of the laser welding with preheating by TIG were confirmed. The material properties of the joints achieved better values and a influence of the welding defects on the quality of the joints was reduced. The Laser-TIG is a good choice for welding galvanized steel sheets in the mass production of automotive industry and it could be improved by more researches.
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Cockerham, Deborah Pyle. "The Impact of an Inquiry-Based Learning Curriculum upon Digital Awareness and Well-Being among Adolescents with Learning and Attentional Disabilities." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609162/.
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This study investigates the effectiveness of an inquiry-based learning curriculum for middle school students with learning and/or attentional disabilities (LD and/or ADHD). The main questions asked were: To what extent can an inquiry-based learning curriculum focused on digital responsibility impact: (1) well-being; (2) smartphone usage; and (3) smartphone awareness among adolescents with LD and/or ADHD? Fifty middle school participants with LD and/or ADHD were divided into two groups, an experimental group and a control group. Findings showed a significant increase both in positive affect and in awareness of personal smartphone usage for experimental, but not control, participants, suggesting that inquiry-based learning may be an effective approach for teaching digital responsibility to students with LD and/or ADHD. Other findings indicated that social connectivity is a high priority for today's adolescents. Additional insights and implications are discussed.
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Li, Yi. "Oxidation Behavior and Thermal Conductivity of Thermoelectric SnSe as well as Laser Powder Bed Fusion Process Modeling and Validation through In-situ Monitoring and Ex-situ Characterization." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546557433304004.
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Valloggia, Sylvie. "SPECTROSCOPIE DE PHOTOLUMINESCENCE LOCALE DANS LES SEMICONDUCTEURS MASSIFS (Si, InP) ET LES PUITS QUANTIQUES (GaAs/GaAlAs)." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37619041b.
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Silva, Lygia Maria Pereira da. "Atendimento a crianÃas e adolescentes em situaÃÃo de abuso sexual: o discurso dos profissionais da saÃde." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=842.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorO abuso sexual de crianÃas e adolescentes representa uma situaÃÃo de risco e uma violaÃÃo de direitos humanos sexuais e particulares da pessoa em desenvolvimento. No atendimento Ãs vÃtimas, os profissionais de saÃde precisam atuar com recursos instrumentais e teÃricos que estÃo alÃm do que os cursos de graduaÃÃo oferecem. Objetivou-se analisar as aÃÃes desenvolvidas pelos profissionais de saÃde no atendimento a crianÃas e adolescentes que sofreram abuso sexual. Buscou-se conhecer os significados atribuÃdos pelos profissionais de saÃde a esse problema. O local onde se deu a pesquisa foi um hospital geral pediÃtrico da cidade de Fortaleza â CE. Realizou-se pesquisa de cunho qualitativo e os sujeitos foram 21 profissionais de saÃde. Os dados foram obtidos atravÃs de entrevista semi-estruturada, gravada. Para anÃlise e organizaÃÃo, utilizou-se a tÃcnica do Discurso do Sujeito Coletivo. Os profissionais foram enfermeiros, mÃdicos, assistentes sociais, psicÃlogas, psicopedagogas. A maioria jamais participou de qualquer treinamento sobre o tema. Constatou-se que os sujeitos entendem o abuso sexual como uma violaÃÃo, uma experiÃncia de sofrimento para a crianÃa, que se apresenta de vÃrias formas. A identificaÃÃo do abuso se dà atravÃs dos sinais e sintomas especÃficos e inespecÃficos, da suspeita a partir do comportamento e do relato da crianÃa e da investigaÃÃo para comprovaÃÃo material. As condutas, apÃs a investigaÃÃo, sÃo encaminhamentos dentro da instituiÃÃo, notificaÃÃo ao Conselho Tutelar, prevenÃÃo e tratamento dos agravos resultantes do abuso e o cuidado com a crianÃa e o adolescente. A existÃncia de uma rotina prÃpria à percebida por alguns atravÃs da atuaÃÃo da ComissÃo de PrevenÃÃo aos Maus-tratos, enquanto outros percebem a existÃncia de uma rotina no hospital em geral e outros afirmam nÃo existir uma rotina. O envolvimento das categorias à percebido a partir da atuaÃÃo na ComissÃo. Alguns sujeitos nÃo sabem como sua categoria està envolvida, enquanto outros entendem que nÃo hà envolvimento, por nÃo haver uma rotina prÃpria. As estratÃgias para qualificaÃÃo dos profissionais adotadas pela instituiÃÃo sÃo consideradas como atividades regulares, esporÃdicas ou inexistentes. O atendimento no serviÃo e na rede de saÃde à visto como possÃvel, a partir dos recursos jà existentes no serviÃo, possÃvel a partir da atuaÃÃo da ComissÃo de PrevenÃÃo aos Maus-tratos e difÃcil, devido ao descrÃdito na rede de assistÃncia. As dificuldades identificadas para o atendimento sÃo a falta de preparo do profissional, emocional, a omissÃo da famÃlia e a insuficiente estrutura do serviÃo. As sugestÃes para melhorar a atuaÃÃo dos profissionais no tema sÃo a capacitaÃÃo e a estruturaÃÃo do serviÃo. Conclui-se que os profissionais de saÃde no serviÃo pesquisado apresentam dificuldades para o atendimento no tocante à capacitaÃÃo, à estruturaÃÃo dos serviÃos e à articulaÃÃo da rede de saÃde e da rede intersetorial. Hà necessidade de fortalecer a ComissÃo, criar normas e rotinas de atendimento, planejar treinamento sobre abuso sexual e sobre outras formas de violÃncia contra crianÃas e adolescentes e implementar parcerias com instituiÃÃes afins, visando à formaÃÃo de redes.
The sexual abuse of children and adolescents consists of a risk situation and a violation of sexual and particular human rights of the person in development. In the attendance to the victims, the health professionals need to act with instrumental and theoretical resources that are beyond what undergraduate courses offer. One aimed to analyze the actions developed by health professionals in the attendance to children and adolescents who suffered sexual abuse. One aimed to know the meanings attributed by health professionals to this problem, considering the subjectsâ context through the Social Representations Theory. The institution where the research was conducted was a pediatric general hospital in the city of Fortaleza â CE. One conducted a qualitative research and the subjects were 21 health professionals. The data were obtained through a recorded semi-structured interview, and for analysis and organization, the Collective Subject Discourse technique was used. The professionals were nurses, doctors, social workers, psychologists and pedagogues, most of them had never taken any training about the theme. One noticed that the subjects understand sexual abuse as a violation, a suffering experience for the children and that has several forms. The identification of the abuse happens through the signals, specific and non-specific symptoms, through the suspect starting from the childâs behavior, through the investigation for material prove and through the childâs report. The conducts after investigation are forwarding inside the institution, notification to the Guardianship Council, prevention and treatment of the traumas resulting from the abuse and the care to the child and the adolescent. The existence of an own routine is noticed by some through the actions of the Mistreatment Prevention Commission, while others notice the existence of a routine in the hospital in general and others argue that there is not a routine. The involvement of the categories is noticed starting from the actions of the Commission. Some subjects do not know how their category is involved, while others understand that there is not involvement, as there is not an own routine. The strategy for qualification of the professionals adopted by the institution is considered as regular, sporadic and non-existent activities. The attendance in the institution and in the health system is seen as possible starting from the resources existing in the service, possible from the actions of the Mistreatment Prevention Commission and hard due to the discredit in the assistance system. The difficulties identified for the attendance are the lack of emotional preparation of the professional, the omission of the family and the insufficient structure of the service. The suggestions to enhance the professionalsâ actions in the theme are the preparation of the professionals and the enhancement of the serviceâs structure. One concludes that the health professionals in the service researched show difficulties for the attendance concerning the preparation, structure of the services and articulation of the health and intersection systems. It is necessary to empower the Commission, create rules and attendance routines, to plan trainings about sexual abuse and other forms of violence against children and adolescents and implement partnerships with similar institutions, aiming to form nets.
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Dal'Bo, Frédéric. "Spectroscopie optique d'heterostructures a base de tellurure de cadmium epitaxiees par jets moleculaires." Grenoble 1, 1988. http://www.theses.fr/1988GRE10123.
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La relaxation des contraintes est mise en evidence par une etude spectroscopique des transitions des excitons libres et varie en fonction de l'epaisseur de la couche et de l'orientation du support. Les differences entre les spectres de photoluminescence des materiaux massifs et ceux des couches epitaxiees sont dues aux effets des contraintes, aux defauts cristallins et aux impuretes introduites pendant la croissance. La structure de bande du puits quantique contraint est etudiee par spectroscopie optique. Elle est etudiee en fonction de l'epaisseur du puits
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Blomster, Kaisa. "Fysisk aktivitet eller Farmakologi för en hälsosammare behandlingsupplevelse enligt individer med ADHD? : Retrospektiv intervjustudie." Thesis, Gymnastik- och idrottshögskolan, GIH, Institutionen för fysisk aktivitet och hälsa, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-6351.
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Introduktion: ADHD är en uppmärksamhet -och hyperaktiv störning, där 90 % i Sverige behandlas med det farmakologiska läkemedlet Metylfenidat (MPH). En stor andel med ADHD utvecklar psykiatrisk komorbiditet i form av psykisk ohälsa (frånvaro av mentalt välbefinnande). Patofysiologin hur MPH påverkar hjärnan är okänd och behandlingsformen har diskuterats som bristfällig på grund av förekommande bieffekter. Fysisk aktivitet har föreslagits som ett hälsosammare behandlingsalternativ, då evidens visat att fysisk aktivitet kan förbättra ADHD-symptom och samsjuklighet av psykisk ohälsa. Det finns inga studier som undersökt hur individer med ADHD upplever nuvarande- och önskar behandling. Syftet med denna studie blev därför att undersöka upplevda erfarenheter av ADHD och hur det farmakologiska läkemedlet MPH och fysisk aktivitet upplevs ha påverkat diagnosens symptom och individernas psykiska hälsa samt att ta reda på vilken behandling individerna önskar utifrån deras livserfarenheter. Metoden utgick från ett fenomenologiskt ramverk med hjälp av en deskriptiv kvalitativ tvärsnittsstudie, där data extraherades genom en innehållsanalys med en induktiv ansats. Urvalet selekterades genom snöbollsurval, där inklusionskriteriet var att deltagarna blivit diagnostiserad med ADHD och har erfarenheter av MPH och fysisk aktivitet. Resultatet visade att symptom för ADHD var problematik med koncentration-, hyperaktivitet-, uppmärksamhet- och systematiska svårigheter, där symptom försämrat den psykiska hälsan. Det framgick att både MPH och fysisk aktivitet effektiviserade symptom mot koncentration, hyperaktivitet och uppmärksamhet, varav KBT (kognitiv beteendeterapi) förbättrade systematiska svårigheter. Vidare bidrog MPH med fysiska, mentala och beteendeföränderliga bieffekter som försämrade den psykiska hälsan. Fysisk aktivitet visade däremot förbättra den psykiska hälsan, där inaktivitet framgick som en central nackdel för förvärring av symptom och psykisk hälsa. Deltagarnas önskan var att behandling bör uppföljas och baseras på en överenskommelse som anpassas efter individuella svårigheter och hälsotillstånd. Slutsatsen med studien kom fram till att behandlas med fysisk aktivitet i kombination med KBT skulle vara hälsosammare som första behandling mot samtliga ADHD-symptom och psykisk hälsa. I andra hand var det deltagarnas önskan att applicera MPH vid akut behov, och är därav förslag att forska fram MPH som engångsbehandling som kan användas vid inaktiva tillstånd. Studien kom fram till att inkludering av fler idrottsvetenskapliga tjänster till vård och skola behövs för mer kompetens om vikten av fysisk aktivitet för individer som har ADHD.Introduction: ADHD is an attention-deficit/hyperactivity disorder, where 90% in Sweden is treated with the pharmacological drug Methylphenidate (MPH). People diagnosed with ADHD develop often psychiatric comorbidity in form of mental illness. The pathophysiology behind how MPH influence the brain is unknown and the treatment have been discussed as deficient due to side effects. Physical activity has been suggested as a healthier treatment option, as evidence shows that physical activity can improve ADHD-symptoms and comorbidity of mental illness. There are no studies that have invastigate how individuals with ADHD experience current- and desired treatment. The aim of this study was therefore to investigate the experiences of having ADHD and how the pharmacological treatment MPH and physical activity has affected the symptoms and mental health, and also find out what treatment the individuals want based on their life experiences. The method was derived from a phenomenological framework using a descriptive qualitative cross-sectional study. Data was analyzed with an inductive approach using an interpretive analysis. Participants was recruited through a snowball selection, where the inclusion criteria stated that participants been diagnosed with ADHD and have experience of MPH and physical activity. The results showed that the frequent occurring symptoms of ADHD were difficulties with concentration-, hyperactivity-, attention- and systematic symptoms, where symptoms had shown a negative effect on the mental health. It appeared that both MPH and physical activity made symptom improvement against concentration-, hyperactivity- and attention difficulties, while CBT (Cognitive Behavioral Therapy) improved systematic difficulties. MPH contributed to side effects that affected physiological-, psychological- and behavioral aspects, which all were perceived to have a negative influence on mental health. In contrast, physical activity improved mental health and showed no evidence of side effects, except when physical activity was absent from daily life. Inactivity appeard to be a central disadvantage for worsening symptoms and mental health. The participants desired that their treatment should be tailored to individual difficulties and health condition in a collaborative way and with follow-up from the health care worker. The study concluded that physical activity in combination with CBT would be a healthier as first treatment option to reduce symptoms of ADHD and improve mental heatlh. Additionally, the participants desired treatment with MPH in form of single doses for urgent need, and it is therefore to suggest development of such treatment option. Furthermore, the study proposes more services for sport science within healthcare and schools for containing applicable knowledge in physical activity for dose with ADHD.
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Sundar, Rajan Sarvesh. "Deep Learning based Defect Classification in X-ray Images of Weld Tubes." 2019. https://monarch.qucosa.de/id/qucosa%3A73092.
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In the scheme of Non Destructive Testing (NDT), defect detection is an important process. Traditional image processing techniques have successfully been used for
defect recognition. Usage of machine learning techniques is still in the initial stages of development. Convolution Neural Networks (CNN) is widely used for object
classification one such scenario is defect classification in weld tubes. With the advent of deep learning techniques such as transfer learning, we can transfer knowledge
gained in one domain successfully into other. Pre-trained models successfully learn features from large scale datasets that can be used for in domains having sparse
data and smaller datasets.
The aim of this work is to help a manual inspector in recognition of defects on the weld tubes. With a given set of images, we proceed by forming unique pipeline
architecture for automatic defect recognition. The research in this thesis focuses on extraction of welds using image segmentation techniques, creating a dataset of defects
and using it to on pre-trained Convolution Neural Networks of VGG16, VGG19, Inception V3 and ResNet101. We evaluate the models on different metrics finding
the best suited model for the created dataset. Further a prototype sliding window solution is used to find defects over the extracted weld region. We also present the
limitations of this approach and suggest modifications that can be implemented in the future.
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Cao, Xiaochao. "WELD READ-THROUGH DEFECTS IN LASER TRANSMISSION WELDING." Thesis, 2010. http://hdl.handle.net/1974/5916.
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In laser Transmission Welding (LTW), the laser beam passes through the transparent part and is dissipated as heat in the absorbent material through the use of laser-absorbing pigments such as carbon black (CB). This energy is then conducted further into both parts. Melting and subsequent solidification occur at the interface causing a weld to form between the two parts.
Gluing or welding structures to the back of automotive Class-A panels often results in the appearance of undesirable surface deformations on the Class-A side. Through control of the laser welding and material parameters, it may be possible to use contour LTW as a means of joining structures to the back of absorbent Class-A panels without creating these unwanted surface defects.
A series of lap welds was made using a range of CB levels, laser powers and polypropylene part thicknesses. A profilometer was used to measure the size and shape of the defects generated on the surface of the black part. Two types of defects were observed: ribs and sink marks. It was observed that lower powers combined with higher carbon black levels generally resulted in smaller defects. The type of defect depended on the boundary conditions between the two parts and the flow of polymer that had thermally expanded during welding (flash). If weld flash flowed into gaps between the two plates, rib defects were always observed. If flash flowed elsewhere and no gaps existed between the plates, sink marks occurred. Finite element modeling was used to qualitatively validate these observations.Thesis (Master, Chemical Engineering) -- Queen's University, 2010-07-02 14:34:41.201
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Kumar, Amit. "Tailoring defect free fusion welds based on phenomenological modeling." 2006. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1309/index.html.
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Chuang, Kai-Cheng, and 莊凱政. "The Influence of Energy Focusing Effect on the Weld Defects." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/gjs22q.
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碩士國立中山大學
機械與機電工程學系研究所
96
The present work researches influence of energy focusing effect to the fusion zone defects in the electron beam welding, which include fusion zone shape, welding depth, welding width, rippling and spiking. And to verify the model of welding defects base on theory and experiment. A spike is a sudden increase in penetration beyond what might be called the average penetration line. Many spikes have voids and cold shuts in their lower portions, because molten metal does not fill in completely, producing a condition similar to a cold shut in a casting. Ripples on a workpiece surface are generally associated with segregation, porosity and other microstructure defects. These become the objectives in this project.
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Jing, Yuan Zhou, and 荊元宙. "In-process detection of weld defects by acoustic emission technique." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/53732067654544492920.
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Pekarun, Osman O. "Evaluation of hydraulic significance of defects in annular well seals." 1995. http://catalog.hathitrust.org/api/volumes/oclc/33124822.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1995.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 142-143).
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Shan, Yi-Pan, and 單亦磐. "The Influence of Welding Defects on the Mechanical Behavior of Ti-6Al-4V Laser Weld." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/11774504078726722252.
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碩士國立臺灣海洋大學
材料工程研究所
92
The influence of weld defects on the undercut properties of Ti-6-4 laser welds was investigation in this work. Experimental results indicated the presence of undercut on the weld surfaces inevitably played an important role on the reduced weld’s ductility, regardless of post-weld treatment. For the weld consisting of a large amount of porosity during tensile straining may lead to a great decrease in ductility. Moreover, the existence of porosity in the weld metal will deteriorate the impact toughness of the weld significantly. The result of fatigue crack growth tests revealed environments have a great influence on the fatigue crack growth rate (FCGR) of Ti-6-4 alloy. As a whole, the FCGR was lower for the specimens tested in vacuum and gaseous hydrogen than the counterpart tested in laboratory air. In general, the defect-free laser weld showed a higher resistance fatigue crack growth than the base plate, owing to the combined microstructural and residual stress effects. The presence of porosity in the weld metal did not accelerate the fatigue crack growth . Although the erratic change of FCGR as the crack tip met the porosity occurred, the blunting of crack tip should be the main causes for the weld with relatively high resistance to crack growth as compared with the defect-free weld.
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王于肇. "Photonic Crystal Multichanneled Filters Containing Coupled and Photonic Quantum-well Defects." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/01514437756301890028.
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碩士國立臺灣師範大學
光電科技研究所
99
In the last two decades, the periodically arranged dielectric structures known as photonic crystals (PCs) have found their potential applications in various optoelectronic devices. The devices make use of the features of photonic band gaps (PBGs) originating from the periodic nature of PCs. When the periodicity is broken by introducing a defect into the PCs, a defect mode will appear inside the photonic bandgap and this is analogous to the electronic impurity state of semiconductors. In this thesis, we consider different defective photonic crystals that can work as a multichanneled filter. Three main topics will be involved. The first structure called the impurity band-based photonic quantum well (IBBPQW) is (AB)m(ABAC)nABA(BA)m , where AB denotes the unit cell, C denotes the defect, and the number of defects is n. The IBBPQW can make more effective use of the localization properties of the electromagnetic (EM) field. The IBBPQW structure can be constructed with great freedom since the impurity band is naturally located inside the gap and the bandwidth of the impurity band can be tuned by changing the separation between the defects and the size or refractive indexes of the defects. In the second structure, we shall consider the photonic quantum-well as a defect in a host PC, i.e., (AB)m(CD)n(AB)m . If the photonic pass band of the photonic crystal(CD)n is just located into the photonic band gap of the photonic crystal (AB)m, quantized confined photonic states will appear owing to the photonic confinement effects. It is found that the number of the confined states can be tuned by adjusting the number of period of the well region, leading to the phenomena of multiple channeled filtering. In the third part, we continue to examine the other condition that the photonic pass band of the photonic crystal (CD)n is partially located into the photonic band gap of the photonic crystal (AB)m. In this case, the number of the confined states can be again tuned by adjusting the number of period of the well region, leading to the phenomena of multiple channeled filtering. However, the number of channels is not the same as the second case. A different design rule will be provided. The whole theoretical analysis in this thesis is based on the transfer matrix method which will be given in Chapter 2. Chapter 1 is to give a brief introduction of PCs. Three main topics are given in Chapters 3, 4 and 5, respectively. The conclusion is in Chapter 6.
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Thomas, Rebecca Ferrell. "Enamel defects, well-being and mortality in a medieval Danish Village." 2003. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-300/index.html.
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Tsai, Chiu-Yun, and 蔡秋韻. "Electrical characteristics of defects in relaxed InGaAs/GaAs single quantum well." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/17852136467654277395.
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碩士國立交通大學
電子物理系
87
Electric defect states are investigated in relaxed InGaAs/ GaAs quantum well to find its position in the bandgap and its relation to the carrier distribution and misfit dislocations by deep-level transient spectroscopy(DLTS),capacitance transient, and admittance spectroscopy. From DLTS, a dominating 0.33~ 0.49eV trap is observed for relaxed InGaAs/GaAs quantum well. This trap level is related to the defect states created by the misfit dislocations introduced by strain relaxation. The depth profile of the trap is found to extend beyond the quantum well region which is consistent with that of carrier distribution, confirming that this 0.33~0.49eV trap plays a significant role in carrier depletion. The depth profile DC/C is found to depend on the measuring frequency for highly relaxed sample. This effect is explained by an existence of a high-resistive layer as observed in capacitance-frequency(C-w)spectra. For the highly relaxed sample, two step-like C-w spectra is observed, with-frequency step corresponding to the emission effect of the 0.33~0.49eV trap and high-frequency step corresponding to the RC time constant effect of the high-resistive layer. The resistance of the high-resistive layer is derived and found to have an activation energy of 0.33~0.49eV, further confirming that carrier depletion is originated from the 0.33~ 0.49eV trap. The resistance derived from C-w spectra also agrees with that derived from current-voltage relation and theory from bulk-limited resistance. The C-w spectra permit us to derive the band diagram and its equivalent circuit model. A new equivalent circuit model with each parameter corresponding to certain physical meaning and including the effect of applied voltage is derived to explain the voltage- and frequency-dependent capacitance for the highly relaxed sample. This circuit model can also be applied to general cases of trap-containing Schottky diodes. The physical meaning of the low-frequency capacitance is illustrated.