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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Non linear, non-local evolution equations : theory and application / Equations d'évolution non-linéaires non-locales : théorie et applications

Nabti, Abderrazak 16 December 2015 (has links)
Cette thèse concerne l’étude qualitative (existence locale, existence globale, explosion en temps fini) de quelques équations de Schrödinger non-linéaires non-locales. Dans le cas où les solutions explosent en temps fini, l’estimation du temps maximal d’existence des solutions sera présentée. Le chapitre 1 concerne l’étude d’une équation de Schrödinger non-linéaire sur RN. On s’intéresse à l’existence locale d’une solution pour toute condition initiale donnée dans L2(RN). De plus, on montre que la norme-L2 de la solution explose en temps fini T < 1. Les démonstrations reposent essentiellement sur le théorème de point fixe de Banach et les estimations de Strichartz, et aussi sur le choix convenable de la fonction test dans la formulation faible du problème. Dans le chapitre 2, on considère une équation de Schrödinger non-linéaire non-locale en temps, et on démontre que les solutions de notre problème explosent en temps fini ; ensuite on obtient des conditions nécessaires d’existence globale. Finalement, on obtient une borne inférieure du temps maximal d’existence de la solution. Le chapitre 3 porte sur la non-existence de solutions d’une équation de Schrödinger non-linéaire posée dans RN. Dans un premier temps, sous certaines conditions sur la donnée initiale, on montre qu’il n’existe pas de solution faible globale ; puis on donne une estimation du temps maximal d’existence de la solution. Enfin, on établit des conditions d’existence locale, ou globale de l’équation considérée. En plus, on généralise les résultats précédents au cas d’un système 2 _ 2. Le dernier chapitre traite une équation de Schrödinger non-linéaire non-locale en temps sur le groupe de Heisenberg H. En utilisant la méthode de la fonction test, on démontre que l’équation n’admet pas de solution faible globale. De plus, on obtient, sous certaines conditions sur les données initiales, une estimation inférieure du temps maximal d’existence de la solution. / Our objective in this thesis is to study the existence of local solutions, existence global and blow up of solutions at a finite time to some nonlinear nonlocal Schrödinger equations. In the case when a solution blows-up at a finite time T < 1, we obtain an upper estimate of the life span of solutions. In the first chapter, we consider a nonlinear Schrödinger equation on RN. We first prove local existence of solution for any initial condition in L2 space. Then we prove nonexistence of a nontrivial global weak solution. Furthermore, we prove that the L2-norm of the local intime L2-solution blows up at a finite time. The second chapter is dedicated to study an initial value problem for the nonlocal intime nonlinear Schrödinger equation. Using the test function method, we derive a blow-up result. Then based on integral inequalities, we estimate the life span of blowing-up solutions. In the chapter 3, we prove nonexistence result of a space higher-order nonlinear Schrödinger equation. Then, we obtain an upper bound of the life span of solutions. Furthermore, the necessary conditions for the existence of local or global solutions are provided. Next, we extend our results to the 2 _ 2-system. Our method of proof rests on a judicious choice of the test function in the weak formulation of the equation. Finally, we consider a nonlinear nonlocal in time Schrödinger equation on the Heisenberg group. We prove nonexistence of non-trivial global weak solution of our problem. Furthermore, we give an upper bound of the life span of blowing up solutions.
232

The Role of Attention and Response Based Learning in the Visual Hebb Supra-span Sequence Learning Task: Investigating Age-related Learning Deficits

Brasgold, Melissa January 2012 (has links)
Using Hebb’s (1961) paradigm, it has been shown that older adults (OAs) fail to learn recurrent visuospatial supra-span sequence information (Turcotte, Gagnon, & Poirier, 2005); a deficit which has not been demonstrated on verbal versions of the same task or in younger adults (YAs). Since the Hebb paradigm is thought to rely on working memory and thus attention (Conway & Engle, 1996), one interpretation concerns an OA’s capacity to allocate the necessary attentional resources to carry out the various components of the task. Five studies investigated this proposal. The first three (Article 1) examined attention in a general manner by reducing the amount of attentional resources that a YA could devote to carrying out the visuospatial Hebb supra-span sequence learning task through the implementation of a verbal dual task (DT) procedure. The fourth (Article 2) further investigated the role of attention by using a DT induced at retrieval that overlapped extensively with the requirements (spatial and response features) of the visuospatial Hebb task. The final study (Article 3) aimed to use our previous findings to demonstrate learning among OAs in a visuospatial Hebb learning paradigm in which the motor response was replaced by a verbal response. Our findings confirm that attentional resources employed at the retrieval phase of the task appear to be particularly important for the demonstration of visuospatial sequence learning. The inclusion of a spatial and motor based DT at recall eliminated learning of the repeated sequence in YAs. Interestingly, the learning deficit of OAs was partially eliminated when the motor and spatial requirements at retrieval were reduced. Our findings offer strong support to the contention that supra-span learning of the Hebb type is not altered by the effect of age. However, learning deficits can be observed among OAs when the retrieval component of the task overly taxes attention-related processes. In the case of the visuospatial sequences, the basis of the deficit likely concerns an individual’s capacity to discriminate between responses made to previously presented sequences versus those that need to be made in reaction to the just seen sequence.
233

Emotional Intelligence at Mid Life: A Cross Sectional Investigation of Structural Variance, Social Correlates, and Relationship to Established Personality and Ability Taxonomies

Chapman, Benjamin P. 08 1900 (has links)
Emotional Intelligence (EI) has been relatively unstudied after young adulthood. Yet there are a variety of reasons to expect that EI may be different at mid life than in young adulthood. Normative life experiences may lead to increases in EI, and as the array of different environments and experiences increases with age, one might expect greater individual differences in EI. Similarly, if EI is located somewhere at the intersection of personality and intelligence, as some have speculated, it may follow a course of structural differentiation similar to cognitive abilities. EI may be more closely linked to social variables such as loneliness and friendships at mid life, and its relation to established personality and ability factors such as the Big Five (Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness) and fluid and crystallized abilities may also vary with age. These hypotheses were investigated in samples of 292 young adults and 246 mid life adults, using the Schutte Self Report Emotional Intelligence Inventory, the NEO-Five Factor Personality Inventory, markers of crystallized and fluid ability from Horn's Crystallized/Fluid Sampler, and a variety of other measures. Mid life adults scored higher on overall EI scores, but evidenced no greater range of individual differences than did young adults. A series of exploratory and confirmatory factor analyses revealed no greater differentiation in the mid life sample either among dimensions of EI or between EI and personality and intelligence variables. Finally, EI appeared equally predictive of social variables in each sample. Results are discussed from the perspective of lifespan and aging literature on emotion, personality, and social functioning. Qualifications for the inference of age-related change in cross sectional designs are considered, along with advantages and disadvantages of factor-analytic and covariance structure modeling methodology. Implications, particularly for psychotherapy with each age group, are discussed.
234

Modellförsök avseende bergspänningars betydelse för spännvidd av valv / The Importance of Rock Stress for the Span of an Arch – Model Test

Larsson, Minna, Skoog, Klara January 2020 (has links)
Tunnels and anthropogenic underground cavities are a very natural part of our everyday modern life. Especially in larger cities such as Stockholm where the infrastructure reaches far above ground level as well as deep below the surface. Metro, commuter train, cars along with many other ways of transportation have been moved below the surface the last century. Before then there were neither the technology nor the knowledge of how tunnels and underground cavities should be constructed so that the safety is not neglected. Several different forces are present in the bedrock below us, such as the weight of the overlying rock/strata and stresses due to tectonic, thermal, or hydrostatic forces among other. Knowledge of these forces and stresses are essential so that you will not get a piece of rock falling on your head on your way home from work with the metro. In most of the cases the roof of tunnels or underground cavities are shaped like an arch, and the stability of these arches depends on several aspects. At excavation of rock, there are natural arches in the bedrock. However, the stability of these arches depends on stresses, amount of overlying rock and the presence of rock joints and fractures (amount, directions and the characteristics of rock joints and fractures are important). These among other aspects determine the stability and the size of the arch. The natural arch in a manmade underground cavity or tunnel is seldom sufficient for it to be safe enough for humans to be in. There is a need for reinforcement of different kinds, where rock bolting is one of the most common. This bachelor’s thesis used a model to simulate arches in tunnels and cavities. The model which simulated an arch was an uplifted box (820x820x250 mm) with railroad macadam, pressure gauges and systematically placed bolts (threaded rods with nuts and washers at each end). The bottom part of the uplifted box could be removed. With a torque wrench the macadam was subjected to different torques, and the bolts were then removed according to a pattern to see at which torques and stresses the model held. The purpose of the thesis was to develop a refined method for bolt model so that controlled experiments could be done. The purpose was as well to determine how important the stresses in the rock is for the span of the arch. The thesis should also function as an instruction for future experiments at the university.  According to the results of the experiments, both lower stresses and higher stresses gave rise to a large arch span. In many cases, an even stress distribution in the model resulted in a greater arch span, but in some cases not. More experiments would have to be done to reach a reliable result. Therefore, there is great potential for other students to continue these experiments. / Tunnlar och bergrum är i modern tid så vanliga att många knappt märker att en befinner sig i ett bergrum i sin vardag. Inte minst i större städer såsom Stockholm där infrastrukturen sträcker sig högt över markytan såväl som långt ner i berggrunden. Tunnelbana, biltrafik, tågtrafik är några transportsätt som ofta har förflyttats under jord det senaste århundradet. Innan dess fanns varken tekniken eller kunskapen om hur tunnlar och bergrum ska konstrueras för att säkerheten ska vara tillräckligt hög. I berget under oss finns det flera krafter som verkar, däribland vikten från ovanliggande berg, spänningar av tektoniska, termala eller hydrostatiska ursprung. Kunskap om dessa spänningar är väsentliga för att du inte ska få ett bergblock i huvudet när åker hem från jobbet med tunnelbanan. I de allra flesta fall har bergrummet eller tunneln ett tak format som ett valv, och stabiliteten av dessa valv beror på flera aspekter. När berguttag sker finns det en naturlig valvverkan som existerar i berget. Höga spänningar, mängden överliggande berg och förekomsten av sprickor (mängd, riktningar och egenskaper hos sprickorna) är några faktorer som påverkar stabiliteten av valvet och hur stort valvet kan vara. Den naturliga valvverkan i en antropogen tunnel är sällan tillräcklig för att valvet ska hålla och vara säkert för människor ska vistas i. Det krävs bergförstärkning av olika typer, där bultförstärkning är vanligt förekommande.  Arbetet gick ut på att simulera valv i berg med hjälp av en modell. Modellen efterliknar ett tunneltak och består av en upphöjd låda (820x820x250mm) med järnvägsmakadam, systematiskt placerade bultar (stänger med bricka och mutter i varje ände) och tryckmätare. Lådan har en avtagbar botten. Experimentet gick ut på att spänna upp makadammet med olika vridmoment, och se vid vilka moment det håller när bultarna succesivt tas bort i en viss ordning. Syftet med arbetet var att ta fram en förfinad metodik för bultmodell så att kontrollerade försök kan genomföras samt fastställa spänningars betydelse för spännvidd av valv. Uppsatsen ska även kunna användas som instruktion för framtida försök vid universitetet.  Resultatet visade att en stor spännvidd uppstod vid både höga och låga spänningar. En jämnare spänningsfördelning gav i flera fall en större spännvidd, men i andra fall inte. Fler försök hade behövt göras för att säkerställa ett pålitligt resultat och det finns därmed stor potential att bygga vidare på experimenten som gjorts.
235

Návrh železničního obloukového mostu přes silnici I/33 / Design of railway arched bridge across the I/33 roadway

Uher, Michal January 2019 (has links)
This master thesis content is alternative design of one span single-railed steel bridge. The bridge is located in km 44,179 on the track Jaroměř - Dvůr Králové. Crossing barrier is roadway I/33. The teoretical distance between supports is 42 m. Main bearing structure is designed as Langer beam. Structure consist of beams, arcs, suspenders, bridge deck with longitudinal and transversal bracings. Elements of the structure are made out of steel S355J2+N, S235J2+N, S355NL. The bridge is designed according to current standards ČSN EN.
236

The Effects of Mindfulness Practice with Music Listening on Working Memory

Messick, Emily Irene 01 January 2019 (has links)
The purpose of this experimental study was to investigate mindfulness strategies and their influence on working memory. The potential role of music in facilitating mindfulness practice is explored. Various listening exercises were investigated along with their influence on working memory (i.e. attention control). Thirty-four individuals were randomly assigned to participate in one of four listening groups: 1) mindfulness with music, 2) mindfulness without music, 3) music only, and 4) silence. Thirty-four participants engaged in a computerized digit-span task before and after the listening exercise to assess pre- and post-test working memory performance. Thirty participants were included in data-analysis due to technical errors in data collection. Differences between listening exercises were explored and comparisons were made between mindfulness, non-mindfulness, music, and non-music based exercises. Two-tailed independent samples t-tests found no significant differences in working memory when comparing mindfulness versus non-mindfulness and music versus non-music based exercises. An Analysis of Variance (ANOVA) indicated no significant differences in working memory for any of the listening conditions. Results call for further examination of control variables and methodology to explore the role of music listening in mindfulness practice. Implications for further research and contributions to music therapy and music education are considered.
237

Statické řešení mostu na dálnici Jánovce-Jablonov / Static solution of bridge on the highway Jánovce-Jablonov

Darebníček, Pavel January 2013 (has links)
The subject of Diploma thesis is the design of bridge on the highway Jánovce - Jablonov and his static solution. Selected variant is made from four span 34+44+44+34m and supporting structure consist of monolithic two beams of prestressed concrete. Height of cross section is over the whole lenght of the bridge constant. Each beams will be built on sliding formwork. The design of supporting structure is made according to limit states, including addressing timing analysis. Calculation of the effects of loading is made by software and reviews are calculated by hand according to Eurocode.
238

Estakáda přes silnici a inundační území / Flyover bridge over a road and inundation territory

Šťavík, Jakub January 2017 (has links)
Master’s thesis describes the design of a highway bridge over the road II/434 and inundation territory. There are some studies designed, from which the main structure was designed as a prestressed concrete double-girder bridge with 5 spans. Loading, design and assessment of structure is solved according to applicable standards CSN and EN. Calculate the effects of the load are carried in calculation program Scia Engineer 2015. Design and asses are carried only by the manual calculation. The thesis includes used materials, construction process, statically analysis and drawing documentation.
239

Lipidové složení biologických membrán a životní strategie pěvců / Lipid composition of biological membranes and life-histories in songbirds

Šimonová, Kateřina January 2020 (has links)
Differences in the composition of cell membranes are considered to be the physiological mechanism responsible for different metabolic rates, life span and consequently, different life-histories. The membrane pacemaker theory suggests that higher membrane unsaturation may be an important factor responsible for higher metabolic rate and shorter life span of organisms. The alternative hypothesis, on the other hand, assumes that membranes can function as structural antioxidants, and thus that higher membrane unsaturation may be associated with longer life span. The aim of this work was to test how changes in the fatty acid composition of membranes depends on body size, latitude and altitude, within which different life-histories and metabolic rate were observed. Temperate and tropical lowland songbird species were chosen for the models testing the effect of latitude, and only tropical species of songbirds were chosen for the models testing the effect of altitude. Part of the work was molecular sex determination. Using gas chromatography and mass spectrometry, the amount of individual fatty acids contained in red blood cell phospholipids was obtained from blood samples. The results showed that the composition of the membranes in most cases correlates with body size, which also correlates with almost all...
240

Multi-axial damage and failure models for thick composite lugs under static and cyclic loading

Rameau, Jean-Michel January 2015 (has links)
The thesis deals with quasi-static and fatigue simulations of thick composite lugs subjected to three-dimensional stress states. This includes damage prediction of hybrid laminates made of GRFP and CRFP containing unidirectional and woven fabric plies.Focus lies on the development of a progressive damage model in fatigue which accounts for sti˙ness and strength degra-dations. Two methods based on Puck’s failure criterion are proposed to predict failure of unidirectional plies: one for plane stress analysis and and the other which takes out-of-plane damage into account.Virtual testing in FEM is conducted in quasi-static and fatigue analysis on thick composite lugs subjected to uni-axial loading. Damage, strength and life predictions are then compared with experimental results to validate the numerical models under investigations. / In der vorliegenden Arbeit wird die Berechnung der Festig-keit von dickwandigen Lochleibungslaminaten im Faserver-bundwerksto˙en unter dreidimensionalen Spannungszustän-den untersucht. Nichtlineare Materialverhalten von Hybrid-laminaten in CFK und GFK werden für Unidirektionalfa-serlagen und Gewebelagen berücksichtigt.Der Schwerpunkt liegt auf der Entwicklung von progressi-ven Versagensmodellen unter der Berüsichtigung von Rest-festigkeit und Reststeifigkeit des Materials. Zwei Modelli-erungsmethoden nach Puck-Kriterium zur Vorhersage des Versagens in UD-Lagen werden vorgeschlagen: eine Degra-dierungstechnik für ebene Spannungszustände und ein me-hrachsiges Modell.Numerische Simulationen mit der Finite-Elemente-Methode werden in Statik- und Ermüdungsanalyse an dickwandigen Lochleibungslaminaten unter einachsiger Belastung durch-geführt. Beschädigungen, Festigkeiten und Ermüdungsle-bensdauer werden dann mit experimentiellen Daten ver-glichen, um die numerischen Methoden zu validieren.

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