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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.
71

Data Logging for Controller Area Network of Autonomous Vehicles : An Investigation of a CAN-Ethernet Gateway / Dataloggning av Controller Area Network för Autonoma Fordon : En undersökning av en nätsluss för CAN-Ethernet

Grönås, Daniel, Mazur, Fredrik January 2022 (has links)
With the development of autonomous vehicles, more and more technology is introduced into the automotive industry. Ethernet has found its way into the vehicle network, and it is forced to coexist with the well-established CAN bus. In terms of data acquisition, the presence of a mixed network brings challenges with significant changes in network architecture. This thesis explores CAN-Ethernet gateways as a replacement for the PCIe bus CAN transceivers utilized in today's logging systems, with the purpose to improve the adaptability of the autonomous logging system. A CAN-Ethernet gateway was implemented using Kvaser's DIN Rail SE400S-X10in an experimental comparison against the PCIe logging solution, including both classical CAN and CAN FD communication. In addition, a case study on the benefits and drawbacks with implementing an Ethernet architecture was performed, utilizing semi-structured interviews. It was concluded that a CAN-Ethernet gateway provides a robust solution in relation to data loss. Throughout the tests, the message loss rate was 0% for both logging solutions. However, CAN-Ethernetlogging introduced additional delay into the system. For the tests on a truck simulation rig the mean additional delay from a CAN-Ethernet gateway, compared to the existing PCIe-CAN logging, was 2 ms. Moreover, some spikes occurred and in a number of cases it could be up to 6 ms in additional delay compared to the existing PCIe logging. It was also proven difficult to time synchronize the gateway with the autonomous logging system, and unknown delays had an impact. Relevant metrics were obtained from relative measurements of side-by-side logging between the PCIe and CAN-Ethernet communication. The standard deviation and fluctuation of the delay were relevant metrics, since smaller fluctuations made the delay more predictable and real-time compatible. A CAN-Ethernet deployment may create a more complex architecture in general, and as of now has limitations for real-time systems. On the other hand, it may offer significant possibilities in future development of a more adaptable and scalable logging system. / Med utvecklingen av autonoma fordon har mer och mer teknologi introducerats inom fordonsindustrin. Ethernet har funnit sin väg in i fordonsnätverket och tvingas existera sida vid sida med den väletablerade CAN-bussen. För dataloggning orsakar närvaron av ett blandat nätverk (med både CAN och Ethernet) utmaningar i samband med stora förändringar inom nätverksarkitektur. Det här examensarbetet utforskar nätslussar för CAN-Ethernet som en ersättare till PCIe-bussens CAN-sändtagare som används i dagens loggningssystem. En CAN-Ethernet-nätsluss implementerades genom att använda Kvasers DIN Rail SE400S-X10 i en experimentell jämförelse med PCIe-loggningssystemet, och inkluderade både klassisk CAN samt CAN FD kommunikation. I tillägg gjordes en fallstudie om fördelar och nackdelar med att implementera en Ethernet-arkitektur,vilken grundades på semi-strukturerade intervjuer. Slutsatsen var att CAN-Ethernet-nätslussar tillhandahåller en robust lösning i förhållande till dataförlust. Under alla testerna var meddelandeförlusten 0% hos båda loggningsmetoderna. Däremot introducerade CAN-Ethernet-loggning en ökad fördröjning till systemet. För testerna på lastbilsriggsimulatorn var fördröjningen 2 ms jämfört med PCIe-CAN-loggningen. Dessutom förekom spikar i fördröjningen och i vissa fall resulterade fördröjningen i upp mot 6 ms, jämfört mot den befintliga PCIe-loggningen. Det visade sig även vara svårt att tidssynkronisera nätslussen med det autonoma loggningssystemet och okända fördröjningar hade en inverkan. Relevanta mått erhölls från relativa mätningar av jämsides loggning mellan PCIe och CAN-Ethernet kommunikation. Standardavvikelsen och fluktuation av fördröjningen var relevanta mått eftersom mindre fluktuationer resulterade i en mer förutsägbar samt realtidskompatibel fördröjning. Användningen av CAN-Ethernet kan, i allmänhet, resultera i en mer avancerad arkitektur och har i dagsläget begränsningar inom realtidssystem. Å andra sidan kan CAN-Ethernet erbjuda markanta möjligheter inom framtida utveckling av ett mer modulärt och skalbart loggningssystem.
72

Analyse numérique de la réponse des pieux sous sollicitations latérales

Hazzar, Lassaad January 2014 (has links)
Résumé : Afin de contribuer dans la réponse latérale des pieux sous sollicitations latérales et notamment prendre en compte des plusieurs paramètres en relation avec les pieux (matériau, diamètre, rigidité, inclinaison) et le sol (nature, rigidité), des analyses numériques en différences finies 2D et 3D ont été réalisées en considérant des pieux chargés latéralement et ancrés dans des sols sableux, argileux et même sableux-argileux. Des modèles numériques simulés avec les codes en différences finies FLAC pour l’analyse 2D et FLAC[indice supérieur 3D] pour l’analyse 3D ont été inspirés des modèles de pieux réduits et en vraie grandeur, faisant l’objet de publications. Des enregistrements du déplacement latéral ou/et de la capacité latérale ou/et du moment fléchissant des pieux considérés ont été pris lors de ces essais. Ces modèles numériques ont été validés à travers diverses comparaisons entre les mesures, les calculs de FLAC et/ou FLAC3D et dans des cas les calculs d’autres méthodes utilisées dans la pratique. Une comparaison entre l’analyse 2D et l’analyse 3D de la réponse latérale d’un pieu rigide chargé latéralement dans un sol cohérent, a été réalisée dans le but de connaître les limites de l’analyse 2D et la possibilité de corréler ses résultats à ceux de l’analyse 3D. L’influence de la charge verticale sur la réponse latérale (capacité latérale et moment fléchissant maximal) d’un pieu en béton, chargé latéralement dans des sols sableux et argileux, a été étudiée avec une analyse numérique 3D. Il a été démontré que pour le cas des sols sableux, la charge verticale n’a pas un effet considérable sur la réponse latérale des pieux soumis à des charges latérales. Par contre, la charge verticale conduit à une diminution significative de la capacité latérale des pieux dans des sols argileux. Il est également constaté que l'influence des charges verticales sur la réponse latérale du pieu installé dans une argile surconsolidée avec une résistance au cisaillement non drainée proportionnelle à la profondeur et un OCR variant de 1,5 à 4,0 est très différent de celle correspondante à une résistance au cisaillement non drainée constante quelle que soit la valeur d’OCR. Des analyses 3D ont été, également, effectuées pour étudier la réponse latérale de pieux inclinés et chargés latéralement. La capacité latérale des pieux inclinés dans les sols sableux est considérablement augmentée avec l’augmentation de la valeur de l’inclinaison du pieu correspondante à la direction opposée à la direction de la charge latérale, et la densité du sable. Mais lorsque la direction de l’inclinaison du pieu et la même que celle correspondante à la charge latérale, cette capacité latérale est légèrement à modérément augmentée tout dépendamment de la valeur et le signe de l'angle ainsi que de la densité du sable. L’influence de l’angle d’inclinaison associé avec la charge verticale sur la capacité latérale de pieux inclinés est aussi très importante pour les sols sableux. Pour les sols argileux, l'influence de l'angle d’inclinaison sur la capacité latérale dépend seulement de l'angle d’inclinaison. En effet, la capacité latérale est modérément augmentée. Par contre, L'effet combiné de l’angle et la charge verticale est assez important. // Abstract : This thesis pertains to numerical analyses conducted primarily to evaluate the lateral response of piles and the contribution of several parameters related to piles (e.g., material, diameter, stiffness, inclination) and the soil (e.g., type, rigidity). Numerical finite differences analysis in 2D and 3D have been performed modelizing laterally loaded piles in sandy, clayey, and even sandy-clayey soils. Numerical models, simulated with finite difference codes FLAC for analysis in 2D and FLAC[superscript 3D] for 3D analysis, were inspired from experimental laboratory and full scale models available in literature. Measurements of lateral deflection and/or lateral capacity and/or bending moment of tested piles were recorded during these tests. These numerical models have been validated through comparison between the various measurements, predictions with FLAC and/or FLAC3D and for some cases the calculations with other methods used in practice. Comparison between 2D and 3D analyses of the response of laterally loaded rigid piles in cohesive soils, was performed in order to investigate the 2D analysis limitations and the possibility of correlating the 2D results with those of 3D analysis. A series of 3D finite differences analyses is also conducted to evaluate the influence of vertical loads on the lateral response of pile foundations. Numerical results have shown that the lateral resistance of the piles does not appear to vary considerably with the vertical load in sandy soil especially at loosest stat. However, vertical load leads to a significant decrease in lateral capacity of piles in homogeneous and inhomogeneous clay layers. It is also found that the influence of vertical loads on the lateral response of pile installed in over-consolidated clay with undrained strength proportional to depth and different OCR in the range of 1.5 to 4.0 is quite different from that with constant undrained strength regardless the adopted OCR value. The 3D finite difference analyses have been, also, carried out to investigate the lateral response of battered piles. The lateral capacity of the battered piles in sandy soils is considerably increased when the value of pile inclination corresponding to the opposite direction of the lateral load increases and when the sand density increases. But in the case of pile inclination corresponding to the same direction of the lateral load, the lateral capacity is slightly increased regardless to the adopted value of batter angle and the sand density. In clayey soil, it was found that the influence of the batter angle on the lateral capacity of piles depends only on the batter angle and not on the clay rigidity. For the case of pile inclination corresponding to the opposite direction of the lateral load, the lateral capacity is moderately increased and for the other case of inclination, the effects are not significant. The influence of both batter angle and vertical load on lateral capacity of battered pile in clayey soils is moderately pronounced.
73

Computation of Thermal Development in Injection Mould Filling, based on the Distance Model

Andersson, Per-Åke January 2002 (has links)
<p>The heat transfer in the filling phase of injection moulding is studied, based on Gunnar Aronsson’s distance model for flow expansion ([Aronsson], 1996).</p><p>The choice of a thermoplastic materials model is motivated by general physical properties, admitting temperature and pressure dependence. Two-phase, per-phase-incompressible, power-law fluids are considered. The shear rate expression takes into account pseudo-radial flow from a point inlet.</p><p>Instead of using a finite element (FEM) solver for the momentum equations a general analytical viscosity expression is used, adjusted to current axial temperature profiles and yielding expressions for axial velocity profile, pressure distribution, frozen layer expansion and special front convection.</p><p>The nonlinear energy partial differential equation is transformed into its conservative form, expressed by the internal energy, and is solved differently in the regions of streaming and stagnant flow, respectively. A finite difference (FD) scheme is chosen using control volume discretization to keep truncation errors small in the presence of non-uniform axial node spacing. Time and pseudo-radial marching is used. A local system of nonlinear FD equations is solved. In an outer iterative procedure the position of the boundary between the “solid” and “liquid” fluid cavity parts is determined. The uniqueness of the solution is claimed. In an inner iterative procedure the axial node temperatures are found. For all physically realistic material properties the convergence is proved. In particular the assumptions needed for the Newton-Mysovskii theorem are secured. The metal mould PDE is locally solved by a series expansion. For particular material properties the same technique can be applied to the “solid” fluid.</p><p>In the circular plate application, comparisons with the commercial FEM-FD program Moldflow (Mfl) are made, on two Mfl-database materials, for which model parameters are estimated/adjusted. The resulting time evolutions of pressures and temperatures are analysed, as well as the radial and axial profiles of temperature and frozen layer. The greatest differences occur at the flow front, where Mfl neglects axial heat convection. The effects of using more and more complex material models are also investigated. Our method performance is reported.</p><p>In the polygonal star-shaped plate application a geometric cavity model is developed. Comparison runs with the commercial FEM-FD program Cadmould (Cmd) are performed, on two Cmd-database materials, in an equilateral triangular mould cavity, and materials model parameters are estimated/adjusted. The resulting average temperatures at the end of filling are compared, on rays of different angular deviation from the closest corner ray and on different concentric circles, using angular and axial (cavity-halves) symmetry. The greatest differences occur in narrow flow sectors, fatal for our 2D model for a material with non-realistic viscosity model. We present some colour plots, e.g. for the residence time.</p><p>The classical square-root increase by time of the frozen layer is used for extrapolation. It may also be part of the front model in the initial collision with the cold metal mould. An extension of the model is found which describes the radial profile of the frozen layer in the circular plate application accurately also close to the inlet.</p><p>The well-posedness of the corresponding linearized problem is studied, as well as the stability of the linearized FD-scheme.</p> / Report code: LiU-TEK-LIC-2002:66.
74

Πρόβλημα αναγνώρισης της αναδίπλωσης μιας πρωτεΐνης : μία πρόταση επίλυσης σε λογικό προγραμματισμό με διαχείριση περιορισμών

Διαμαντόπουλος, Νικόλαος 05 February 2015 (has links)
Η κατανόηση των μοριακών μηχανισμών της ζωής απαιτεί την αποκωδικοποίηση των λειτουργιών που εκτελούν οι πρωτεΐνες σε έναν οργανισμό. Δεκάδες χιλιάδες πρωτεΐνες έχουν μελετηθεί τα τελευταία χρόνια σε στόχο την εύρεση της τρισδιάστατης δομής τους που στην ουσία καθορίζει και την λειτουργία τους. Παρ’ όλα αυτά οι πειραματικές μέθοδοι που χρησιμοποιούνται παρότι είναι ακριβείς μέθοδοι είναι ακόμα ιδιαιτέρως δύσκολες και απαιτητικές σε χρόνο και οικονομικό κόστος. Για το λόγο αυτό επιχειρείται, με υπολογιστικές μεθόδους, να μειωθεί το κόστος της πρόβλεψης της 3D δομής μιας πρωτεΐνης όταν η γραμμική ακολουθία των αμινοξέων που την αποτελούν είναι γνωστή. Η παρούσα διπλωματική εργασία προσεγγίζει το πρόβλημα αυτό ως πρόβλημα βελτιστοποίησης για τη λύση του οποίου εφαρμόζεται μία δηλωτική προσέγγιση σε Λογικό Προγραμματισμό με Διαχείριση Περιορισμών. Η πρόταση βασίζεται σε ένα προσωποκεντρικό κυβικό πλέγμα ως τοπολογικό μοντέλο για την χωροθέτηση της πρωτεΐνης. Χρησιμοποιούνται επίσης πληροφορίες που αφορούν τυχόν δευτερεύουσες δομές που υπάρχουν στην πρωτεΐνη καθώς και άλλα heuristics για να περιοριστεί σημαντικά ο χώρος αναζήτησης. Τα πρώτα αποτελέσματα σε πραγματικές πρωτεΐνες είναι ενθαρρυντικά τόσο όσο αφορά την ακρίβεια και την χρονική επίδοση αλλά και όσον αφορά την κλιμάκωση του προβλήματος. / Understanding the molecular mechanisms of life requires decoding functions performed by proteins in an organism. Tens of thousands of proteins have been studied in recent years in order to recruit the three-dimensional structure, which essentially determines their function. Nevertheless, the test methods used although accurate methods are still very difficult and demanding time and financial cost. For this reason computational methods are used to reduce the cost of the provision of 3D structure of a protein when its linear sequence of amino acids is known. This thesis approaches the problem as an optimization problem for the solution of which is applied a declarative approach to Logic Programming with Constraint Management. The proposal is based on a face centered cubic lattice as a topological model for the location of the protein. Also used information concerning possible secondary structures present in the protein and other heuristics to significantly reduce the search space. First results on real proteins are promising both in terms of accuracy and time performance, but also regarding the escalation of the problem.
75

Inversion acoustique tridimensionnelle des formes d'onde complètes : méthodes algorithmes et application au réservoir pétrolier de Valhall / Three-dimensional acoustic Full Waveform Inversion : method, algorithms and application to the Valhall petroleum field

Hu, Guanghui 21 September 2012 (has links)
L'imagerie quantitative des propriétés physiques du sous-sol est fondamentale pour de nombreuses applications impliquant des échelles d'exploration très variées: géotechnique pour l'imagerie de la proche surface, exploration à l'echelle crustale, reconstruction lithosphérique et imagerie globale pour la compréhension fondamentale des processus géodynamiques, mais aussi pour l'exploitation optimale des ressources du sous-sol.Parmi les méthode géophysiques, les méthodes sismiques ont le pouvoir de résolution le plus élevé. La densification des dispositifs d'acquisition, la mise au point de sources et de capteurs large bande et l'augmentation de la puissance de calcul ouvrent de nouvelles perspectives pour le développement et l'application de méthodes non conventionnelles d'imagerie sismique pour une extraction plus complète de l'information contenue dans les données sismiques. Parmi ces méthodes d'imagerie non conventionnelles, les méthodes d'inversion du champ d'onde complet, fondées sur la résolution complète de l'équation d'onde pour le problème direct (modélisation sismique) et la résolution d'un processus d'optimisation pour le problème inverse, font actuellement l'objet de nombreux développements méthodologiques, tant au sein des communautés industrielles qu'académiques.Le challenge numérique est la résolution du problème direct en trois dimensions pour un grand nombre de sources sismiques caractéristique des acquisitions pétrolières massives, et le challenge méthodologique est la gestion de la non-linéarité du problème inverse résultant de l'éclairage incomplet du sous-sol depuis la surface par des sources de bande-passante limitée. L'apport attendu de ces méthodes est la résolution de l'imagerie sismique de l'ordre de la demi-longueur d'onde propagée, sa capacité à imager des cibles complexes d'un point de vue structural notamment sous des écrans salifères ou basaltiques et la quantification des paramètres physiques caractérisant le sous-sol tels que la vitesse de propagation des ondes de compression à laquelle peuvent s'ajouter la densité, l'atténuation, la vitesse de propagation des ondes de cisaillement et des paramètres caractérisant l'anisotropie du milieu.L'objectif de cette thèse est de poursuivre le développement d'une méthode d'imagerie sismique acoustique 3D par l'inversion du champ d'onde complet et de l'appliquer à des données réelles pétrolières 3D de fond de mer enregistrées sur le champ pétrolier de Valhall en Mer du Nord et de fournir une des premières évaluations du potentiel des méthodes d'inversion des formes d'onde pour l'imagerie de milieux géologiques 3D L'inversion est effectuée en domaine fréquentiel où un nombre limité de fréquences est inversé suivant un protocole hiérarchique maintenant bien éprouvé procédant des basses fréquences vers les hautes fréquence: cette approche multi-échelle favorise la prise en compte de la non-linéarité du problème inverse.L'approche de modélisation en domaine temporel avec extraction du champ monochromatique par une transformée de Fourier discrète est effectuée pour calculer les champs d'onde monochromatique nécessaires à la résolution du problème inverse. L'algorithme d'optimisation du problème inverse est fondé sur une méthode de gradients conjugués préconditionés ou sur une méthode quasi-Newton. Les méthodes sont appliquées dans le cadre de l'approximation visco-acoustique isotrope où le milieu est paramétré par la vitesse de propagation des ondes de compression, l'atténuation et la densité. Seule, la composante hydrophone acquise en fond de mer est inversée. L'enjeu méthodologique de cette thèse est de fournir un modèle tri-dimensionelle du champ pétrolier de Valhall dans un cube de dimensions approximatives 18 km x 12 km x 5 km en poussant l'inversion à la fréquence la plus élevée possible. / Quantitative imaging of the subsurface physical properties is fundamental to many applications involving very various explorations, such as geotechnical imaging of the near surface, petroleum exploration, crustal lithospheric exploration. This helps us to understand the fundamental of geodynamic processes and also to exploit the resources of subsurface. Among the geophysical methods, seismic methods can give a higher resolution. The improvements of the acquisition in size and density, the multifold/multicomponent wide-aperture and wide-azimuth acquisitions, and the increased high-performance computing power open new perspectives to develop and apply non-conventional seismic imaging methods for extraction more complete and continuous information in the seismic data. Among these non-conventional methods, the full waveform inversion method based on the complete resolution of the wave equation for the direct problem (seismic modeling) and the resolution of optimization process for the inverse problem, are currently the subject of many methodological developments, in both industrial and academic communities. The numerical challenge is the resolution of the three-dimensional direct problem for a large number of seismic sources, typically few to tens of thousands in petroleum industry acquisition. The methodological challenge is the management of the non-linearity of the inverse problem resulting from the incomplete illumination of subsurface from the surface survey with a limited bandwidth source. The expected contribution of these methods is to reach a spatial resolution of half-a-wavelength. It has the ability to image complex structure targets such as saline or salt-bearing basaltic and to quantify the subsurface physical parameters such as velocity, density, attenuation, anisotropic parameters and so on. The objective of this thesis is to develop a method of three-dimensional seismic imaging by full waveform inversion and apply it to real ocean-bottom data set recorded in the Valhall oil field (in the North Sea) and to provide an early evaluation of the potentialities of full waveform inversion for imaging three-dimensional geological environments . The inversion is performed in frequency domain. A limited number of frequencies is inverted following a hierarchical protocol from low to high frequencies. This multi-scale approach helps to reduce the non-linearity of the inverse problem. The modeling approaches is performed in time domain and monochromatic wavefields are extracted by discrete Fourier transform to solve the inverse problem in frequency domain. The optimization algorithm of the inverse problem is based on conjugate gradients method or quasi-Newton method. The method is applied in the framework of the visco-acoustic isotropic approximation, where the medium is parameterized by the velocity of compressional wave propagation, attenuation, and density. The hydrophone data component located at the seabed is inverted. The methodological issue of this thesis is to develop by full waveform inversion a three-dimensional high-resolution velocity model of the Valhall oil field in a cube with a size of 18 km $\times$ 12 km $\times$ 5 km, and to push the inversion towards frequencies as high as possible.
76

Computation of Thermal Development in Injection Mould Filling, based on the Distance Model

Andersson, Per-Åke January 2002 (has links)
The heat transfer in the filling phase of injection moulding is studied, based on Gunnar Aronsson’s distance model for flow expansion ([Aronsson], 1996). The choice of a thermoplastic materials model is motivated by general physical properties, admitting temperature and pressure dependence. Two-phase, per-phase-incompressible, power-law fluids are considered. The shear rate expression takes into account pseudo-radial flow from a point inlet. Instead of using a finite element (FEM) solver for the momentum equations a general analytical viscosity expression is used, adjusted to current axial temperature profiles and yielding expressions for axial velocity profile, pressure distribution, frozen layer expansion and special front convection. The nonlinear energy partial differential equation is transformed into its conservative form, expressed by the internal energy, and is solved differently in the regions of streaming and stagnant flow, respectively. A finite difference (FD) scheme is chosen using control volume discretization to keep truncation errors small in the presence of non-uniform axial node spacing. Time and pseudo-radial marching is used. A local system of nonlinear FD equations is solved. In an outer iterative procedure the position of the boundary between the “solid” and “liquid” fluid cavity parts is determined. The uniqueness of the solution is claimed. In an inner iterative procedure the axial node temperatures are found. For all physically realistic material properties the convergence is proved. In particular the assumptions needed for the Newton-Mysovskii theorem are secured. The metal mould PDE is locally solved by a series expansion. For particular material properties the same technique can be applied to the “solid” fluid. In the circular plate application, comparisons with the commercial FEM-FD program Moldflow (Mfl) are made, on two Mfl-database materials, for which model parameters are estimated/adjusted. The resulting time evolutions of pressures and temperatures are analysed, as well as the radial and axial profiles of temperature and frozen layer. The greatest differences occur at the flow front, where Mfl neglects axial heat convection. The effects of using more and more complex material models are also investigated. Our method performance is reported. In the polygonal star-shaped plate application a geometric cavity model is developed. Comparison runs with the commercial FEM-FD program Cadmould (Cmd) are performed, on two Cmd-database materials, in an equilateral triangular mould cavity, and materials model parameters are estimated/adjusted. The resulting average temperatures at the end of filling are compared, on rays of different angular deviation from the closest corner ray and on different concentric circles, using angular and axial (cavity-halves) symmetry. The greatest differences occur in narrow flow sectors, fatal for our 2D model for a material with non-realistic viscosity model. We present some colour plots, e.g. for the residence time. The classical square-root increase by time of the frozen layer is used for extrapolation. It may also be part of the front model in the initial collision with the cold metal mould. An extension of the model is found which describes the radial profile of the frozen layer in the circular plate application accurately also close to the inlet. The well-posedness of the corresponding linearized problem is studied, as well as the stability of the linearized FD-scheme. / <p>Report code: LiU-TEK-LIC-2002:66.</p>
77

The Acquisition of Transitivity Alternations by Bilingual Children / A Comparative Study

Grey, Christina 08 June 2020 (has links)
In Griechisch werden Transitivitätsänderungen durch non-aktives Genus Verbi (Voice) ausgedrückt, was zu einer morphologischen Unterspezifikation führt. Grundsätzlich können passive und reflexive Verben im Griechischen (neben anderen Strukturen) mit derselben Form ausgedrückt werden. Oft ist der Kontext das einzige Mittel zur Disambiguierung. Diese Studie untersucht den Erwerb von Transitivitätsalternationen (transitivity alternations) bei griechischen monolingualen Kindern im Vergleich zu zwei zweisprachigen Populationen, nämlich griechisch-deutschen und griechisch-englischen Kindern im Alter zwischen 4 und 8 Jahren. Es wird untersucht, ob beim Erwerb der jeweiligen morphologischen Systeme die dominante Sprache, in diesem Fall Deutsch bzw. Englisch, mit der Erbsprache (Heritage- sprache) Griechisch interagiert. Englisch und Deutsch unterscheiden sich vom Griechischen, indem sie Reflexivität und Passivierung anders ausdrücken, und stellen deswegen ein in- teressantes Forschungsgebiet dar. In der Studie wurden 80 zweisprachige Kinder sowie 40 einsprachige Kinder untersucht. Sie sollten die folgenden “Spiele” absolvieren: Ren- frews (1998) expressive Vokabelaufgabe, angepasst an das Griechische von Vogindroukas (2009), sowie zwei experimentelle Aufgaben: eine Wahrheitsbewertungsaufgabe (truth-value judgement task) und eine Handlungsaufgabe (act-out task). Die Ergebnisse zeigen, dass Passive Verben sind hingegen am schwierigsten zu verstehen und zu produzieren, sowohl für zweisprachige als auch für monolinguale griechische Kinder. / In Greek, transitivity alternations are expressed using the non-active voice resulting in a morphological underspecification. Essentially, passives and reflexives in Greek, among other structures, can be expressed using the same form; context is often the only means of disambiguation. This study investigates the acquisition of transitivity alternations in Greek comparing two bilingual populations namely, Greek-German and Greek-English bilinguals between the ages of 4 and 8. This study was motivated by the lack of research on the acquisition of transitivity alternations in bilingual populations. It examines whether the dominant language, in this case German and English respectively, interacts with the heritage language, Greek, as they both evolve morphologically. English and German differ from Greek in the way they express reflexivity and passivisation and posed an interesting area of research. 80 bilingual children as well as 40 monolingual children a baseline task: Renfrew’s (1998) Expressive Vocabulary Task adapted for Greek by Vogindroukas (2009) and two experimental tasks: a truth-value judgement task (TVJT) and an act-out task (AOT). The findings show that children across populations scored worst in passives thus replicating the results in previous literature.
78

A Methodology for Transitioning Maritime Hardwired Communication to Controller Area Network

Lavén, Astrid January 2024 (has links)
A ship’s communication system serves as a vital infrastructure to host real-time applications,facilitating the transmission of crucial data, including sensor readings and control commands. Theexpansive dimensions of a ship necessitate a complex network of cables in an analogue hardwiredsetup, stretching from the bridge to the machinery. However, this reliance on multiple cables introduces logistical challenges and vulnerabilities within the system architecture. This thesis establishesa systematic approach for transitioning ship control systems from traditional analogue hardwiredconfigurations to more efficient Controller Area Network (CAN) bus-based systems. CAN is amulti-master communication protocol that enables multiple controllers to communicate with eachother without a host computer, making it particularly suitable for complex environments. While alternative networking options such as Ethernet or wireless networks are available, CAN emerges as acost-effective and robust communication solution suited for maritime environments. The transitionto CAN-based systems not only prolongs the ship’s operational lifespan but can also enhance fuelefficiency and reduce environmental impact. Ensuring a seamless transition requires careful consideration of safety and functionality equivalent to legacy systems. Extensive research into suitablecommunication buses, CAN protocols, and scheduling algorithms is essential. By exploring Controller Area Network with Flexible Data-Rate (CAN FD) as a complement to CAN 2.0, the tool offersmultiple solutions, with the optimal choice contingent upon various parameters. A comprehensive tool has been developed to facilitate the safe migration from hardwired systems to CAN-basedsolutions. This tool enables the mapping of signals to messages, priority assignment using various algorithms, including Audsley’s optimal priority assignment algorithm, and real-time analysis.This work will assist in the transition by presenting diverse solutions, clearly outlining deadlines,identifying potential misses, and recommending the most effective combination of methods.
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Finite element study of geosynthetic encased stone columns in sensitive soft clay

Zhang, Rongan, Engineering & Information Technology, Australian Defence Force Academy, UNSW January 2009 (has links)
Some normally consolidated soft soils manifest strength sensitivity, ie these soil manifest strain softening when shear in an undrained mode. These soils, referred to as sensitive soft soils, have the typical features of strain hardening in drained shearing and strain softening in undrained shearing. The consolidation lines of these soils are also curved (concave upwards) in the semi-log space. However, under high consolidation stress or upon large shearing, these soils re-gain the features of re-constituted soil. Ground improvement methods like stone columns were reported as not effective when installed in the sensitive soft clays. But mechanism of the un-effectiveness of the stone columns remains unknown because of lack of a suitable and simple model for simulating the stress-strain behaviours of sensitive soft soils. Although these soils have a meta-stable micro-structure, models that developed for simulating structured firm soils are not suitable for simulating sensitive soft soil features. Thus, a new model was formulated. The new model can degenerate back to a Modified Cam Clay model. The ability of new model in simulating a range of behaviour was verified by using the finite difference (FD) method in solving the partial differential equations of the soil model for a range of tri-axial test conditions. The model was further implemented in coupled analysis formulation and coded into FEM program AFENA. Various cases with different soil parameters were then simulated and compared with the FD solutions for various triaxial tests so as to check the stability of the FEM code. The coupled FEA was then used to simulate the performance of geosynthetic-encased stone columns. A new stone column element and a geo-encasement element were developed and coded into AFENA. The stone column simulations were then done for both non-sensitive soils (represented by Modified Cam Clay model) and sensitive soft soil (represented by the new model). Parametric study was conducted to examine the performance of the geo-encased stone columns in both types of soils. Furthermore, two different installation methods: wished-in installation and full displacement installation were studied numerically. Cross comparison was done to investigate how the sensitive soft soil features interact with the installation method in affecting the performance of the geo-encased stone columns. A range of factors that influence the geosynthetic-encased stone columns performance installed in soft soils were also made clear.
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Investigation of driving mechanisms of combustion instabilities in liquid rocket engines via the dynamic mode decomposition

Quinlan, John Mathew 07 January 2016 (has links)
Combustion instability due to feedback coupling between unsteady heat release and natural acoustic modes can cause catastrophic failure in liquid rocket engines and to predict and prevent these instabilities the mechanisms that drive them must be further elucidated. With this goal in mind, the objective of this thesis was to develop techniques that improve the understanding of the specific underlying physical processes involved in these driving mechanisms. In particular, this work sought to develop a small-scale, optically accessible liquid rocket engine simulator and to apply modern, high-speed diagnostic techniques to characterize the reacting flow and acoustic field within the simulator. Specifically, high-speed (10 kHz), simultaneous data were acquired while the simulator was experiencing a 170 Hz combustion instability using particle image velocimetry, OH planar laser induced fluorescence, CH* chemiluminescence, and dynamic pressure measurements. In addition, this work sought to develop approaches to reduce the large quantities of data acquired, extracting key physical phenomena involved in the driving mechanisms. The initial data reduction approach was chosen based on the fact that the combustion instability problem is often simplified to the point that it can be characterized by an approximately linear constant coefficient system of equations. Consistent with this simplification, the experimental data were analyzed by the dynamic mode decomposition method. The developed approach to apply the dynamic mode decomposition to simultaneously acquired data located a coupled hydrodynamic/combustion/acoustic mode at 1017 Hz. On the other hand, the dynamic mode decomposition's assumed constant operator approach failed to locate any modes of interest near 170 Hz. This led to the development of two new data analysis techniques based on the dynamic mode decomposition and Floquet theory that assume that the experiment is governed by a linear, periodic system of equations. The new periodic-operator data analysis techniques, the Floquet decomposition and the ensemble Floquet decomposition, approximate, from experimental data, the largest moduli Floquet multipliers, which determine the stability of the periodic solution trajectory of the system. The unstable experiment dataset was analyzed with these techniques and the ensemble Floquet decomposition analysis found a large modulus Floquet multiplier and associated mode with a frequency of 169.6 Hz. Furthermore, the approximate Rayleigh criterion indicated that this mode was unstable with respect to combustion instability. Overall, based on the positive finding that the ensemble Floquet decomposition was able to locate an unstable combustion mode at 170 Hz when the operator's time period was set to 1 ms, suggests that the dynamic mode decomposition based 1017 Hz mode parametrically forces the 170 Hz mode, resulting in what could be characterized as a parametric combustion instability.

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