Dissertations / Theses on the topic 'Secondary ageing'
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Marvier, Allison Christina. "Effects of ageing on primary and secondary transport processes in red beet (Beta vulgaris) storage tissue." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295952.
Full textBuha, Joka School of Materials Science & engineering UNSW. "Interrupted ageing of Al-Mg-Si-Cu alloys." Awarded by:University of New South Wales. School of Materials Science and engineering, 2005. http://handle.unsw.edu.au/1959.4/20794.
Full textXu, Dapeng. "Time effects on soil behavior : a particulate-scale study on the mechanisms of secondary consolidation and ageing /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202006%20XU.
Full textMarceau, Ross Kevin William. "Design in Light Alloys by Understanding the Solute Clustering Processes During the Early Stages of Age Hardening in Al-Cu-Mg Alloys." University of Sydney, 2008. http://hdl.handle.net/2123/4008.
Full textThe evolution of atomistic-level nanostructure during the early stages of both standard, high-temperature T6 heat treatment, and low-temperature secondary ageing after interruption of the former (T6I4), has been investigated in rapid hardening Al-Cu-Mg alloys using a variety of microscopy and microanalytical techniques, including transmission electron microscopy (TEM), positron annihilation spectroscopy (PAS) and atom probe tomography (APT). In order to carry out this objective, quantitative data-analysis methods were developed with respect to new cluster-finding algorithms, specifically designed for use with three-dimensional APT data. Prior to this detailed characterisation work, the actual thermal impact from both heat treatment and quenching of small, lab-scale specimens was determined through correlation of both experimental results and calculations that modelled the heat transfer conditions using the lumped capacitance method. Subsequently, the maximum diffusion distance by random walk of the solute atoms was calculated for these periods, bearing significance on the propensity for these atoms to have the ability to cluster together, rather than segregate to the dislocation loops in the microstructure, which have a relatively larger interspacing distance. Age-hardening curves for the Al-1.1Cu-xMg (x = 0, 0.2, 0.5, 0.75, 1.0, 1.7 at.%) alloys at 150ºC show that the rapid hardening phenomenon (RHP) exists for Mg compositions ≥ 0.5Mg. Given that zone-like precipitate structures were unable to be detected by TEM or APT during the early stages of ageing at 150ºC, and that statistically significant dispersions of clusters were found in the APT data after ageing for 60 s, the RHP is attributed to these clustering reactions. Identification of clusters in the APT data has been achieved using the core-linkage algorithm and they have been found to be quite small, containing only a few atoms up to a couple of tens of atoms. The RHP is governed by some critical number density of both Mg clusters and Cu-Mg co-clusters of a critical size, whereas Cu clusters do not contribute significantly to the hardening mechanism. Significance testing indicates that Mg clusters are more significant at smaller clusters sizes and Cu-Mg co-clusters more important at larger cluster sizes. Hardness results also confirm the existence of rapid early hardening during secondary ageing at 65ºC in Al-1.1Cu-1.7Mg. The mechanism of secondary rapid hardening involves a combination of both secondary clustering from solute (mainly Mg atoms) residual in solution, and pre-existing amorphous primary clusters that have slower growth kinetics at the lower secondary ageing temperature. The latter occurs mainly by vacancy-assisted diffusion of Mg atoms as evidenced by the gradual increase of the Mg:Cu ratio of co-clusters. From an alloy design point of view it is important to fully understand the solute distribution in the microstructure to be able to subsequently optimise the configuration for enhanced material properties. The change in dispersion of solute atoms during ageing was determined by combining calculations of % vacancy-solute associations with detailed measurements of the dislocation loops to estimate the solute distribution within the microstructure. The implication of the balance of solute atoms segregated to the loops compared with that in the matrix is then discussed in the context of hardnening mechanisms.
Remes, T. (Tiina). "Signs of radiation-induced accelerated ageing in survivors of childhood brain tumors:the incidence of cerebrovascular disease, neurocognitive impairment, secondary neoplasms, and low bone mineral density after 18 years of follow-up." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526224305.
Full textTiivistelmä Taustaa: Suomessa sairastuu vuosittain 46-60 lasta aivokasvaimeen, joka on lapsuusiän yleisin, kiinteä kasvain. Selviytyneillä on todettu lisääntynyt hoitojen myöhäisvaikutuksien riski. Kuitenkin nuorten aikuisten haittavaikutuksia on toistaiseksi tutkittu melko vähän. Tutkimuksen tarkoitus: Tarkoituksena oli selvittää sädehoidon jälkihaittoina esiintyvien sairauksien, kuten aivoverisuonisairauksien, älyllisten ongelmien, sekundaaristen kasvainten ja luustonhaurastumisen yleisyyttä ja riskitekijöitä suomalaisessa, kansallisessa kohortissa. Aineisto ja Menetelmät: Tutkimukseen kutsuttiin kaikki Suomessa lapsuusiällä aivokasvaimen sairastaneet aikuiset, jotka oli hoidettu sädehoidolla vuosina 1970-2008. Tutkittavat olivat yli 16-vuotiaita ja hoitojen päättymisestä oli yli 5 vuotta. Osallistuneille tehtiin kliininen ja neuropsykologinen tutkimus, pään magneettikuvaus, luustontiheysmittaus ja laboratoriotutkimuksia. Tulokset: Tutkimukseemme osallistui 74 nuorta aikuista 18,9 ± 6,1 vuotta hoitojen päättymisen jälkeen. Tutkittavat olivat iältään 28,4 ± 6,8 -vuotiaita osallistuessaan, ja 8,3 ± 4,3 -vuotiaita diagnoosihetkellä. Aivoverisuonisairaus todettiin 52% tutkimukseen osallistuneella 20 vuoden seurannan jälkeen, pienten suonten tauti oli 38 %:lla ja suurten suonten tauti 16 %:lla. Aivoinfarktin oli sairastanut 9 % tutkituista, lakuunainfarktin 10 % ja aivoverenvuodon 3 % tutkituista. Valkean aivoaineen muutoksia todettiin 49 %:lla magneettikuvauksessa. Korkea verenpaine lisäsi aivoverisuonisairauden, suurten suonten taudin, valkoisen aivoaineen muutoksien sekä lakuunainfarktien riskiä. Selviytyjien keskimääräinen kielellinen älykkyysosamäärä oli 89 ± 14 ja ei-kielellinen 87 ± 19. Suurimmat vaikeudet todettiin toiminnanohjauksessa (Z-luku -5,0 ± 5,3 SD) ja prosessointinopeudessa (Z-luku -4,3 ± 5,4 SD). Toiminnanohjauksen ja prosessointinopeuden vaikeudet olivat yhteydessä arkielämän haasteisiin. Sekundaaristen aivokalvokasvainten kumulatiivinen esiintyvyys oli 25 vuoden seuranta-aikana 10,2 % kliinisessä tutkimuksessa ja sekundaaristen kasvainten 2,4 % Syöpärekisteriaineistossa. Matala luustontiheys todettiin 23,6%:lla selviytyneistä. Johtopäätökset: Nuorilla aikuisilla, jotka ovat lapsena aivokasvaimen vuoksi saaneet sädehoitoa, esiintyy useita sellaisia jälkihaittoja, jotka yleensä liittyvät ikääntymiseen
Jacumasso, Sheila Cristina. "CARACTERIZAÇÃO MICROESTRUTURAL DAS PARTÍCULAS DE SEGUNDA FASE DE UMA LIGA DE ALUMÍNIO AA7050 NAS CONDIÇÕES T7451, T6 E T6I4-65." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2014. http://tede2.uepg.br/jspui/handle/prefix/1460.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
The AA7050 class from the 7XXX series alloys based on Al-Zn-Mg-Cu are widely used in aerospace structures and fuselage components, when the same are subjected to high stress loading due to its high ratio mechanical strength to density, in addition, to its corrosion resistance. The increased resistance of these alloys is obtained by heat treatment that involves solution treatment and ageing followed precipitation of a fine and homogeneous phase from the own chemical composition. In this, the present study aimed to perform the of AA7050 aluminum alloy microstructural characterization with different ageing heat treatment from the T7451, T6 and T6I4-65 conditions. Thus, different characterization techniques from the Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Extraction of second phase particles, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) were used. It was evaluated which condition results is higher precipitation hardening phases that are responsible for the increased resistance of the alloy. The most significant results were obtained by TEM where it was possible to determine the morphology of the GPII zones in needles form with approximate size of 30nm and 10nm for both T6 and T6I4-65 conditions, respectively. Moreover, the metastable η' phase was identified in platelets form in the T7451, T6 and T6I4-65 conditions with approximate size of 50nm, 20nm and 10nm, respectively. The surface roughness analyses obtained by AFM have revealed that the T6I4-65 condition has higher surface roughness (Ra=14,87nm) when compared to the T7451 (Ra=7,65nm) and T6 (Ra=8,35nm) conditions. Indicating in this case, a higher density of small particles homogeneously distributed in the T6I4-65 aluminum alloy matrix.
As ligas da série 7XXX, da classe AA7050, à base de Al-Zn-Mg-Cu, são muito utilizadas na indústria aeroespacial, em estruturas de fuselagem e componentes sob alta tensão de carregamento, devido à sua alta relação entre resistência mecânica e densidade, além de sua resistência à corrosão. O aumento da resistência destas ligas é obtido por tratamento térmico de solubilização e envelhecimento, através da precipitação de uma fase fina e homogênea, proveniente da própria composição química. Neste contexto, o presente trabalho teve como objetivo principal realizar a caracterização microestrutural de uma liga de alumínio AA7050, submetida a diferentes tratamentos térmicos de envelhecimento nas condições T7451, T6 e T6I4-65. Desse modo, fez-se o uso de diferentes técnicas de caracterização entre elas Microscopia Ótica (MO), Microscopia Eletrônica de Varredura (MEV), Microscopia de Força Atômica (AFM), Extração de Partículas de segunda fase, Difração de Raios X (DRX) e Microscopia Eletrônica de Transmissão. Consequentemente, avaliou-se qual condição apresenta maior precipitação de fases endurecedoras que são responsáveis pelo aumento de resistência da liga. Os resultados mais significativos foram obtidos por MET onde foi possível determinar a morfologia das zonas GPII presentes na forma acicular (needles) com tamanho aproximado de 30nm na condição T6 e 10nm na condição T6I4-65. A fase metaestável η’ foi identificada na forma de plaquetas finas (platelets) nas condições T7451, T6 e T6I4-65 com tamanho aproximado de 50nm, 20nm e 10nm respectivamente. A rugosidade superficial obtida por AFM revelou que a condição T6I4-65 apresenta maior rugosidade superficial (Ra=14,87nm) quando comparado às condições T7451(Ra=7,65nm) e T6 (Ra=8,35nm), indicando maior densidade de partículas de pequena dimensão distribuída homogeneamente na matriz da liga de alumínio.
Martinez, Jessica. "Exploring the Long-Term Impact of an Institutional Agent| Success of the Freedom Writers." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13425593.
Full textDemonstrated by this study, teachers as institutional agents can make a significant difference in the lives of their students during their educational endeavors and beyond. However, institutional agents remain rare within urban education, and adolescents’ access to these individuals in low-income communities is particularly low. This study used Stanton-Salazar’s theory of social capital and construct of institutional agents as a lens to understand the experiences of 14 individuals who participated in the Freedom Writers program. By giving a voice to students two decades after completing high school, this study conveys a critical perspective to the urban educational field. With there being a limited understanding of the lasting impact of such individuals on students as they transition onto adulthood participants’ personal accounts were explored to better understand their experiences.
As a qualitative study, this research inquired into the actions that guided the participants at the individual and situational level to having successful experiences. Data collection occurred through the utilization of an in-depth, semi-structured interviewing method, which provided rich data of the roles and functions of their high school teacher, Erin Gruwell, as an institutional agent. Additionally, providing data of their use of certain supports as provided by or made possible through Gruwell, four themes emerged from the findings of this study: (1) survival mode, (2) journey to Freedom Writers, (3) finding support, and (4) life after Freedom Writers. Within these themes, an in-depth exploration of the findings indicated the careful attention Gruwell placed in assessing the needs of students in order to provide the necessary supports as permitted by her social network and available resources, which involved access to additional institutional agents or other networks; significant forms of information; and other supportive forms of resources. The findings further indicated there being a critical impact to participants’ social development, and academic and career success. Through positive teacher-student relationships teachers can provide positive educational experiences that can have lifelong implications to empower students and create opportunities for life changes. Through the perspectives of the 14 participants, this study can influence the work of practitioners and policymakers in focusing on the needs and concerns of students attending urban high schools as well as in supporting teachers as institutional agents at the high school level.
Tones, Megan Jane. "Patterns of engagement in workplace learning amongst employees from social sectors." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/31248/1/Megan_Tones_Thesis.pdf.
Full textSivan, Atara. "Attitudes of secondary school students and teachers towards the aim of school as a socialising agent for leisure /." Thesis, [Hong Kong : University of Hong Kong], 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13009515.
Full textDussart, François Mathieu Didier. "Genomic analysis of secondary metabolism in Ramularia collo-cygni, causative agent of Ramularia leaf spot disease of barley." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28829.
Full textMoushey, Douglas Lee. "Formation of Mesoporosity in Zeolite and Mesoporous Molecular Sieve Structures through use of Carbon as a Secondary Templating Agent." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218657179.
Full textChatzikos, Nikolaos. "Influence of fluxing agent on the quality of recycled Aluminium billets." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231166.
Full textKvaliteten hos aluminiumgöt är starkt beroende av renheten i materialet. Hydro Extruded Solutions gjuter rundgöt i Sjunnen, som sedan levereras för strängpressning inom samma företag. För att producera strängpressade profiler av hög kvalitet och även upprätthålla pressverktygen, är en bra metod att hålla göten så fria från inneslutningar som möjligt. Ett flussmedel, i form av saltföreningar, används för att rena materialet under smältningen, men också för att skydda den från vidare oxidation. En annan uppgift som flussmedel har är att minimera mängden aluminium i slaggfasen. Syftet med detta projekt var att undersöka om flussmedelet som används av omsmältverket har någon inverkan på götkvaliteten. Därför, för detta ändamål har prover med en varierande mängd av flussmedel tillverkats i omsmältverket för att bli undersökta. Dessa prover undersöktes med den Optiskt Mikroskopiska-metoden för att bestämma areafraktionen av icke-metalliska inneslutningar inuti dem. Resultaten avslöjade inte någon signifikant skillnad i kvaliteten hos de olika proverna eftersom de flesta prover erhöll ett lågt OM-index efter undersökningen. Detta kan förklaras av vilken typ av skrot som användes, då process-skrot oftast är väldigt rent och består av mindre mängder innseslutningar.
Bahi, Muhammad [Verfasser], Hartmut [Akademischer Betreuer] Laatsch, and Axel [Akademischer Betreuer] Zeeck. "Bandamycin as New Antifungal Agent and further Secondary Metabolites from Terrestrial and Marine Microorganisms / Muhammad Bahi. Gutachter: Hartmut Laatsch ; Axel Zeeck. Betreuer: Hartmut Laatsch." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1043991387/34.
Full textSvalmark, Per. "Ta parti! : Gymnasieelevers uppfattade påverkan inför riksdagsvalet 2010." Thesis, Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-6798.
Full textPersson, Ingrid. "Fritidshuset som planeringsdilemma." Doctoral thesis, Karlskrona : Blekinge Institute of Technology, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00483.
Full textfritidshus, planeringsdilemma, fysisk planering, lagstiftning, dubbel bosättning, miljöbalken, annonser, fastighetsmäklare, Lefebvre, Laclau, Mouffe
Boarman, McKaila J. S. "Trade-offs and Temporal Variation in Predator-Mediated Natural Selection and Sexual Selection on the Wings of the Damselfly Calopteryx splendens." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1491746850419119.
Full textEl-Tayeb, El-Sayed Mohamed. "Rétention d'alpha-oléfinésulfonates de sodium dans un sable argilo-calcaire : étude expérimentale et modélisation du transport en présence de cations divalents et d'asphalte." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL149N.
Full textSmirnova, Maria. "Contrats de travail et problèmes d'allocation des ressources dans les universités russes - Une approche en termes des modèles multitâches." Phd thesis, Université Panthéon-Sorbonne - Paris I, 2010. http://tel.archives-ouvertes.fr/tel-00510024.
Full textSoutif, Jean-Claude. "Etude de l'addition des acides carboxyliques sur les structures oxiranne : application aux polymeres epoxydes." Le Mans, 1987. http://www.theses.fr/1987LEMA1010.
Full textZhou, Yu-Xiang, and 周煜翔. "Secondary Voltage Control in Power Systems Using Multi-Agent Reinforcement Learning." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/10683077823926962493.
Full text國立清華大學
資訊工程學系
102
To protect power systems against different severe disturbances, the ways to effectively control voltage have become the important issue in power systems. In light of that, a Multi-Agent System (MAS) structure has been proposed to deal with the issue of voltage regulation. With our system, once the voltage violations occur, the agents would detect the abnormality and try to eliminate these voltage violations by injecting the reactive power. Besides, to make a good decision under abnormal conditions, a reinforcement learning scheme has been proposed to provide better and faster regulation. Based on the concept of distributed control, there are two parts in our reinforcement learning scheme, self-regulated learning and cooperative learning. On the other hand, an altruistic rate has been proposed to consider the impact of other neighbor agents. The performance of the proposed multi-agent reinforcement learning are demonstrated using various conditions in a benchmark of power networks.
Bahi, Muhammad. "Bandamycin as New Antifungal Agent and further Secondary Metabolites from Terrestrial and Marine Microorganisms." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-F047-B.
Full textVerdy, Julie. "Le savoir professionnel des conseillers pédagogiques québécois des ordres primaire et secondaire : analyse descriptive." Thèse, 2005. http://hdl.handle.net/1866/17799.
Full textTessier-Jasmin, Jean-Michel. "Analyse exploratoire de la délinquance scolaire et de l'implication policière dans les écoles secondaires défavorisées de Montréal." Thèse, 2006. http://hdl.handle.net/1866/18163.
Full textAlmeida, Ana Paula Fagulha de. "Formação do ozono troposférico: simulação e modelação por agentes - identificação de áreas críticas nos municípios de Porto e Matosinhos." Master's thesis, 2018. http://hdl.handle.net/10362/43437.
Full textEste trabalho pretende fornecer um método complementar de determinação das zonas mais afetadas pelo poluente ozono dentro da área do município do Porto e de Matosinhos, tendo em vista ser um elemento de apoio à decisão com utilidade na aplicação de medidas de adaptação às alterações climáticas. Para tal são efetuadas análises de distribuição espacial de poluentes a partir das medições existentes validadas oficialmente pela Agência Portuguesa do Ambiente, para determinar quais as áreas onde estes atingem concentrações mais elevadas. A análise espacial foi efetuada primeiro numa fase exploratória dos dados e representada num sistema de informação geográfica. Nesta fase foram efetuadas interpolações espaciais que permitiram concluir os níveis de exposição da população dentro da área de estudo. Seguidamente foi programada uma modelação por agentes, uma vez que a formação do ozono se trata de um sistema complexo (formado por reação fotoquímica a partir de poluentes primários e as condições ambientais adequadas), onde interagem diversos agentes. Os resultados permitiram um estudo mais detalhado ao nível da seção estatística, identificando aquelas onde o aparecimento do ozono pode ser mais problemático, sendo um complemento aos mapas de previsão existentes para este tipo de poluente, atualmente existentes apenas para a escala regional.
This work intends to provide a complementary method to determine the zones most affected by the pollutant ozone within the area of the city of Porto and Matosinhos, in order to be a useful decision support element in the application of climate change adaptation measures. For this purpose, analyses of the spatial distribution of pollutants are carried out, from existing measurements officially validated by the Portuguese Environment Agency, to determine the areas where this pollutant reaches higher concentrations. Spatial analysis was performed, first in an exploratory phase of the data and represented in the ArcGIS geographic information system. In this phase, spatial interpolations were carried out to conclude the exposure levels of the population within the study area. Ozone formation is a complex system (it is a secondary pollutant formed by photochemical reaction from primary pollutants) with multiple agents interacting with each other over time. An agent based model was coded to simulate this phenomenon. The results allowed a more detailed study at a level of the statistical block group, being a complement to the existing forecast maps for this type of pollutant, currently available only at the regional scale.
Burns, C. J., E. Fantino, A. K. Powell, Steven D. Shnyder, Patricia A. Cooper, S. Nelson, C. Christophi, et al. "The microtubule depolymerizing agent CYT997 causes extensive ablation of tumor vasculature in vivo." 2011. http://hdl.handle.net/10454/5902.
Full textAdam, Kathija. "The role of department heads as change agents in the implementation of educational reform in the United Arab Emirates." Thesis, 2005. http://hdl.handle.net/10500/2382.
Full textEducational Studies
D.Ed (Education Management)
Rezková, Aneta. "Vliv rodiny na výběr povolání u žáků ZŠ." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-306906.
Full text