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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.
81

A Monte Carlo Study to Determine Sample Size for Multiple Comparison Procedures in ANOVA

Senteney, Michael H. January 2020 (has links)
No description available.
82

Enabling One-Way Leases of Temperature Controlled Containers: A Heuristic Model / Envägsuthyrning av Temperaturkontrollerade Containrar: En Konceptuell Modell

FORSBERG, SEBASTIAN, SVENSSON, ANTON January 2018 (has links)
There is an asymmetry in demand for transportation means of goods and commodities globally. One industry in which this trend is especially prominent is the pharmaceutical industry, where the European Union is by far the largest net exporter of pharmaceutical products globally, followed by Switzerland. The largest global net importer of pharmaceutical products is America, and given that many pharmaceutical products need to be transported in a cold chain, a niche within the transportation industry has grown – one that focuses primarily on transportation of high-value temperature-sensitive goods. Transportation companies working with circulating assets around the world need to determine how much capacity can be allocated to the sale of one-way trips (which may displace assets within the fleet to places in which they cannot be sold again due to the lack of business) whilst still allowing the sale of round-trip leases to continue. We conducted a case study within Company A that is a cold chain provider for air freight to provide context on how a heuristic model for capacity control should be developed, and incorporated this with learnings from theory within the fields of revenue management and fleet management together with literature in similar business settings. This resulted in a four-step model with unique planning horizons for each level, ranging from strategic perspectives for fleet balancing down to operational aspects of daily allocation and release of containers. We conclude which factors are essential for the context of the case study and showcase how a model can be constructed taking these findings into account. The thesis deals with the issue of capacity control for one-way leases. Other models have used pricing strategies to accomplish similar tasks and this is not included in the proposed model which is a limitation of this study, this is discussed and elaborated on. Furthermore, possible implications for the customer behaviour with the suggested model is discussed. / Det finns en global asymmetri i efterfrågan för transport av gods och råvaror. En industri där detta är speciellt framstående är läkemedelsindustrin – där Europa är den största exportören globalt följt av Schweiz. Den största importören av dessa produkter är Nordamerika, och givet att många läkemedelsprodukter behöver transporteras i en kylkedja har en nisch inom transportsektorn vuxit fram – en som fokuserar primärt på transport av temperaturkänsligt gods av högt värde. Transportbolag som jobbar med cirkulerande tillgångar världen över behöver bestämma hur mycket kapacitet som kan allokeras till envägsuthyrningar (vilket kan fördela flottan så att ingen efterfrågan finns för att sälja dessa igen) medan den fortsatta försäljningen av tur-och-retur-uthyrningar fortfarande tillåts. Vi utför en fallstudie inom Företag A, som tillhandahåller tjänster för kylkedjor gjorda för flygfrakt, detta för att skapa förståelse för hur en heuristisk modell för kapacitetskontroll kan utvecklas. Detta vävs samman med lärdomar från teori inom fälten intäktsoptimering och förvaltning och styrning av utrustningsflottor tillsammans med litteratur inom liknande affärskontexter. Detta resulterade i en fyrstegsmodell med unika planeringshorisonter för varje nivå. Modellen sträcker sig från strategiska beslut för balansering av flottan ner till operationella aspekter för daglig allokering och överlåtande av containrar. Vi sammanfattar vilka faktorer som är relevanta inom ramarna för fallstudien och visar hur en modell kan vara uppbyggd där dessa faktorer tas i beaktning. Avhandlingen hanterar problemet kapacitetskontroll för envägsuthyrningar. Andra modeller har använt prissättningsstrategier för att åstadkomma liknande mål och detta har inte inkluderats i den föreslagna modellen vilket är en begränsning i avhandlingen, detta diskuteras och vidareutvecklas. Möjliga implikationer på kundbeteende med den föreslagna modellen diskuteras också.
83

A Data-driven Approach to Identify Opportunities to Reduce Missing Doses

Lydick, Jaide E. 21 September 2016 (has links)
No description available.
84

Signal design for multi-way relay channels

Sharifian, Shaham 20 December 2016 (has links)
Today’s communication systems are in need of spectrally efficient and high throughput techniques more than ever because of high data rate applications and the scarcity and expense of bandwidth. To cope with increased data rate demands, more base stations are needed which is not cost and energy efficient in cellular networks. It has been shown that wireless relay networks can provide higher network throughput and increase power efficiency with low complexity and cost. Furthermore, network resources can be utilized more efficiently by using network coding in relay networks. A wireless relay network in which multiple nodes exchange information with the help of relay node(s) is called a multi-way relay channel (MWRC). MWRCs are expected to be an integral part of next generation wireless standards. The main focus of this dissertation is the investigation of transmission schemes in an MWRC to improve the throughput and error performance. An MWRC with full data exchange is assumed in which a half-duplex relay station (RS) is the enabler of communication. One of the challenges with signal demodulation in MWRCs is the existence of ambiguous points in the received constellation. The first part of this dissertation investigates a transmission scheme for full data exchange in MWRC that benefits from these points and improves its throughput by 33% compared to traditional relaying. Then an MWRC is considered where a RS assists multiple nodes to exchange messages. A different approach is taken to avoid ambiguous points in the superposition of user symbols at the relay. This can be achieved by employing complex field network coding (CFNC) which results in full data exchange in two communication phases. CFNC may lead to small Euclidean distances between constellation points, resulting in poor error performance. To improve this performance, the optimal user precoding values are derived such that the power efficiency of the relay constellation is highest when channel state information is available at the users. The error performance of each user is then analyzed and compared with other relaying schemes. Finally, focusing on the uplink of multi-way relay systems, the performance of an MWRC is studied in which users can employ arbitrary modulation schemes and the links between the users and the relay have different gains, e.g. Rayleigh fading. Analytical expressions for the exact average pairwise error probability of these MWRCs are derived. The probability density function (PDF) and the mean of the minimum Euclidean distance of the relay constellation are closely approximated, and a tight upper bound on the symbol error probability is developed. / Graduate
85

Using a Repeated Measures ANOVA Design to Analyze the Effect Writing in Mathematics Has on the Mathematics Achievement of Third Grade English Language Learners and English Speakers

Morales, Zoe A 07 November 2016 (has links)
The gap that exists between English language learners and English speaking students’ achievement in mathematics continues to grow. Moreover, students are now required to show evidence of their mathematics knowledge through writing in standardized assessments and class assignments. The purpose of this study was to analyze students’ writing in mathematics and the metacognitive behaviors they portrayed through their writing as they solved mathematics problems. The instruments included a pretest, two biweekly tests, and a posttest. The writing instruction encompassed students learning to solve problems by using Polya’s four phases of problem solving which was completed in 12 sessions over a period of 6 weeks. Garofalo and Lester’s framework which renamed Polya’s phases into orientation, organization, execution, and verification, was used to look at the metacognitive behaviors students used. The participants included 67 students enrolled in four third grade classes, who were English language learners and English speakers. This research followed a quasi-experimental design, with a treatment group and a control group. A one-way repeated ANOVA was used to analyze the data. The findings showed no significant difference between the mathematics achievement scores of treatment and control. However, growth trends in achievement scores revealed that the treatment group scores were increasing faster than the control group scores across the four tests during the 6-week study. Moreover, significant differences were found between the treatment and the control groups when the problem solving with metacognitive behaviors scores were analyzed. Descriptive statistics showed the frequency of occurrence of each of the problem solving phases increased steadily across the four tests for the students in the treatment group. During the posttest, 100% of treatment group students wrote about metacognitive behaviors they used during the orientation and organization phases, 91.4% wrote about their metacognition for executing the solution, and 80% wrote about the verification process they followed. These findings are useful to education professionals who are interested in creating programs for teaching mathematics at the elementary level that include effective problem solving practices. This evidence-based method may be adopted in school districts with large populations of ELLs in order to assist these students when solving problems in mathematics.
86

Nouvelle technique de grilles imbriquées pour les équations de Saint-Venant 2D / New nested grids technique for 2D shallow water equations

Altaie, Huda 17 December 2018 (has links)
Les écoulements en eau peu profonde se rencontrent dans de nombreuses situations d’intérêts : écoulements de rivières et dans les lacs, mais aussi dans les mers et océans (courants de marée, tsunami, etc.). Ils sont modélisés par un système d’équations aux dérivées partielles, où les inconnues sont la vitesse de l’écoulement et la hauteur d’eau. On peut supposer que la composante verticale de la vitesse est petite devant les composantes horizontales et que ces dernières sont indépendantes de la profondeur. Le modèle est alors donné par les équations de shallow water (SWEs). Cette thèse se concentre sur la conception d’une nouvelle technique d’interaction de plusieurs grilles imbriquées pour modèle en eau peu profonde en utilisant des méthodes numériques. La première partie de cette thèse comprend, La dérivation complète de ces équations à partir des équations de Navier- Stokes est expliquée. Etudier le développement et l’évaluation des méthodes numériques en utilisant des méthodes de différences finies et plusieurs exemples numériques sont appliqués utilisant la condition initiale du niveau gaussien pour 2DSWEs. Dans la deuxième partie de la thèse, nous sommes intéressés à proposer une nouvelle technique d’interaction de plusieurs grilles imbriquées pour résoudre les modèles océaniques en utilisant quatre choix des opérateurs de restriction avec des résultats de haute précision. Notre travail s’est concentré sur la résolution numérique de SWE par grilles imbriquées. A chaque niveau de résolution, nous avons utilisé une méthode classique de différences finies sur une grille C d’Arakawa, avec un schéma de leapfrog complété par un filtre d’Asselin. Afin de pouvoir affiner les calculs dans les régions perturbées et de les alléger dans les zones calmes, nous avons considéré plusieurs niveaux de résolution en utilisant des grilles imbriquées. Ceci permet d’augmenter considérablement le rapport performance de la méthode, à condition de régler efficacement les interactions (spatiales et temporelles) entre les grilles. Dans la troisième partie de cette thèse, plusieurs exemples numéériques sont testés pour 2DSWE avec imbriqués 3:1 et 5:1. Finalement, la quatrième partie de ce travail, certaines applications de grilles imbriquées pour le modèle tsunami sont présentées. / Most flows in the rivers, seas, and ocean are shallow water flow in which the horizontal length andvelocity scales are much larger than the vertical ones. The mathematical formulation of these flows, so called shallow water equations (SWEs). These equations are a system of hyperbolic partial differentialequations and they are effective for many physical phenomena in the oceans, coastal regions, riversand canals. This thesis focuses on the design of a new two-way interaction technique for multiple nested grids 2DSWEs using the numerical methods. The first part of this thesis includes, proposing several ways to develop the derivation of shallow water model. The complete derivation of this system from Navier-Stokes equations is explained. Studying the development and evaluation of numerical methods by suggesting new spatial and temporal discretization techniques in a standard C-grid using an explicit finite difference method in space and leapfrog with Robert-Asselin filter in time which are effective for modeling in oceanic and atmospheric flows. Several numerical examples for this model using Gaussian level initial condition are implemented in order to validate the efficiency of the proposed method. In the second part of our work, we are interested to propose a new two-way interaction technique for multiple nested grids to solve ocean models using four choices of higher restriction operators (update schemes) for the free surface elevation and velocities with high accuracy results. Our work focused on the numerical resolution of SWEs by nested grids. At each level of resolution, we used explicit finite differences methods on Arakawa C-grid. In order to be able to refine the calculations in troubled regions and move them into quiet areas, we have considered several levels of resolution using nested grids. This makes it possible to considerably increase the performance ratio of the method, provided that the interactions (spatial and temporal) between the grids are effectively controlled. In the third part of this thesis, several numerical examples are tested to show and verify twoway interaction technique for multiple nested grids of shallow water models can works efficiently over different periods of time with nesting 3:1 and 5:1 at multiple levels. Some examples for multiple nested grids of the tsunami model with nesting 5:1 using moving boundary conditions are tested in the fourth part of this work.
87

Даљинско управљање дигиталном пнеуматиком у концепту Индустрије 4.0 / Daljinsko upravljanje digitalnom pneumatikom u konceptu Industrije 4.0 / Remote control of the digital pneumatics in a scope of Industry 4.0

Reljić Vule 28 August 2020 (has links)
<p>У овој докторској дисертацији, акценат је стављен на анализу даљински<br />управљаних дигиталних пнеуматских система у концепту Индустрије 4.0.<br />Доприноси тезе су сљедећи: 1) Показано је на који начин је могуће, постојеће<br />пнеуматске системе надградити тако да се омогући даљинско управљање<br />кретањем пнеуматских радних елемената, даљинска регулација притиска и<br />даљинска регулација протока. 2) Показано је на који начин је могуће развити<br />даљински управљан дигитални пнеуматски систем, који има могућност<br />даљинске промјене управљачких параметара (радног притиска и/или<br />протока) у току процеса рада, и који је искључиво софтверски<br />реконфигурабилан, те реализован на оптималан начин, чиме достиже ниво<br />флексибилности потребан да се задовољи основни концепт Индустрије 4.0.<br />Примјена добијених резултата могућа је у свим индустријским, а потом и<br />неиндустријским системима, у којима постоје пнеуматски радни елементи.</p> / <p>U ovoj doktorskoj disertaciji, akcenat je stavljen na analizu daljinski<br />upravljanih digitalnih pneumatskih sistema u konceptu Industrije 4.0.<br />Doprinosi teze su sljedeći: 1) Pokazano je na koji način je moguće, postojeće<br />pneumatske sisteme nadgraditi tako da se omogući daljinsko upravljanje<br />kretanjem pneumatskih radnih elemenata, daljinska regulacija pritiska i<br />daljinska regulacija protoka. 2) Pokazano je na koji način je moguće razviti<br />daljinski upravljan digitalni pneumatski sistem, koji ima mogućnost<br />daljinske promjene upravljačkih parametara (radnog pritiska i/ili<br />protoka) u toku procesa rada, i koji je isključivo softverski<br />rekonfigurabilan, te realizovan na optimalan način, čime dostiže nivo<br />fleksibilnosti potreban da se zadovolji osnovni koncept Industrije 4.0.<br />Primjena dobijenih rezultata moguća je u svim industrijskim, a potom i<br />neindustrijskim sistemima, u kojima postoje pneumatski radni elementi.</p> / <p>In this PhD thesis, the emphasis is placed on the analysis of remotely<br />controlled digital pneumatic systems in the scope of Industry 4.0. The<br />contributions of the thesis are the following: 1) The possibility of upgrading an<br />existing pneumatic systems to allow remote motion control of pneumatic<br />actuators, remote pressure control and remote flow control, is shown. 2) The<br />possibility of developing a remotely controlled digital pneumatic system, which<br />has the ability of remote change of the control parameters (the operating<br />pressure and/or the flow) during the operating process, and which is<br />exclusively software reconfigurable and optimally implemented, is shown. At<br />that way, it is achieving a level of flexibility needed to meet the basic concept<br />of Industry 4.0. The application of the obtained results is possible in all<br />industrial and then non-industrial systems, where pneumatic actuators exist.</p>
88

Bytový dům Panoráma Boskovice - dopravní řešení / Panorama Boskovice Apartment Hose - design of transport

Werner, David January 2019 (has links)
The diploma thesis deals with the project of transport solution for new buildings of BD Panorama Boskovice. The project documentation elaborates the design of the road, sidewalks and parking spaces to the proposed 4 apartment buildings in Boskovice The work corresponds to the extent of the design documentation for construction (PDPS).
89

Listen Up! : A study of how teachers in SLA approach the listening skill within upper secondary schools in Sweden

Andersson, Julia, Lagerström, Elin January 2020 (has links)
Listening comprehension and listening strategies plays a crucial role in the process of acquiring a language. This study aims to investigate to what extent the listening skill is practised in upper secondary schools in the south of Sweden. Research studies within the field of listening are few which indicates that the listening skill is not considered as essential in second language teaching as the other three skills: reading, writing and speaking. Previous studies indicate that teachers should educate students metacognitive awareness when teaching listening. The results summarize the teachers’ answers, reflections and attitudes conducted from semi-structured interviews. The analysis of the results focuses on the four categories distinguished from the teachers’ answers: Teaching Approaches, National Exams, The Individual Student and Metacognitive Awareness. Some of the teachers do not possess the knowledge of how to teach listening that develops students' listening proficiency. As a conclusion, the study shows that a hierarchy exists among the four skills to which teachers adjust to, and this may be detrimental in achieving educational aims.
90

Computational Study of the Injection Process in Gasoline Direct Injection (GDI) Engines

Martínez García, María 02 September 2022 (has links)
[ES] La creciente preocupación por los problemas medioambientales, la disponibilidad de combustibles fósiles unido a la gran demanda de vehículos, han llevado a los gobiernos a regular las emisiones emitidas a la atmósfera. Existen propuestas de adoptar fuentes de energía renovables. Sin embargo, la sustitución de los combustibles derivados del petróleo no será fácil, rápida o rentable, y el transporte propulsado por motores de combustión interna (ICE) seguirá destacando en los próximos años. La eficiencia de la combustión y el rendimiento del motor están influenciados por el complejo proceso de inyección. La inyección directa de gasolina (GDI) aumenta el ahorro de combustible y cumple los requisitos de emisiones contaminantes, aunque queda potencial por descubrir. Por ello, ha sido objeto de estudio en los últimos años y, en consecuencia, de la presente Tesis. Este trabajo tiene como motivación mejorar el entendimiento en el campo del GDI. La compleja naturaleza transitoria del proceso de inyección hace que el estudio experimental sea un desafío. La Mecánica de Fluidos Computacional (CFD) surge como una potente alternativa a los experimentos y ha sido adoptada para esta investigación. Bajo este contexto, el objetivo de la presente Tesis es desarrollar una metodología predictiva para la caracterización hidráulica del inyector, capaz de ser aplicada a las actuales y futuras generaciones de inyectores GDI, independientemente de las características del inyector y del software de estudio. Una vez validada, el objetivo posterior es utilizar los resultados para analizar el comportamiento del chorro. Este enfoque busca seguir los pasos de la comunidad científica sustituyendo la práctica experimental. La validación de la metodología se lleva a cabo mediante su aplicación en dos inyectores GDI solenoides multi-orificio diferentes. Además, se han utilizado dos códigos CFD comerciales: CONVERGE y StarCCM+. La metodología predictiva se centra en el estudio del flujo interno y el campo cercano para caracterizar hidráulicamente el inyector. El problema a tratar se define como un sistema multifásico en un marco Euleriano y considerando un único fluido. El tratamiento del flujo multifásico se realiza mediante el enfoque Volume-of-Fluid (VOF). Además, se emplea el Homogeneous Relaxation Model (HRM) para considerar el intercambio de masa entre las fases líquida y vapor debido a cavitación y flash boiling. La turbulencia se ha tratado a partir de los enfoques Reynolds-Averaged Navier-Stokes (RANS) y Large Eddy Simulations (LES). Por otro lado, en cuanto al estudio del flujo externo, se ha adoptado el Discrete Droplet Model (DDM). La atomización y el chorro están influenciados por la geometría de la tobera, por lo que la estrategia de acoplamiento del flujo interno y externo complementa los análisis. Se han adoptado enfoques de acoplamiento unidireccional y mapeado, utilizando como parámetros de entrada los datos de flujo interno de la validada metodología. Esta Tesis aporta una nueva y valiosa metodología predictiva con una elevada precisión a la hora de caracterizar el proceso de inyección en comparativa con datos experimentales. Por otro lado, es directamente trasferible a distintos códigos de cálculo así como aplicable a inyectores con características dispares sin perjudicar las exigencias del modelo. La correcta caracterización del flujo interno ha permitido emplear los datos obtenidos para analizar el comportamiento del chorro eliminando la necesidad de usar datos experimentales. Los resultados obtenidos capturan el comportamiento macroscópico del chorro con una precisión comparable a los experimentos. Aunque todavía hay muchos retos que afrontar, la presente Tesis supone un gran avance en el campo del GDI. El remarcable progreso se debe al desarrollo y uso de una metodología totalmente predictiva, que permite prescindir de la mayoría de los experimentos para contribuir a una mayor y más amplia visión de la física del proceso de inyección. / [CA] La creixent preocupació pels problemes ambientals, la limitada disponibilitat de combustibles fòssils, acompanyat a la gran demanda de vehicles, ha portat el govern a regular els nivells d'emissions emesos a l'atmosfera. Existeixen propostes d'adoptar fonts d'energia renovables. Tanmateix, la substitució dels combustibles líquids derivats del petroli no es durà a terme de forma fàcil, ràpida o rentable, i el transport propulsat per motors de combustió interna (ICE) continuarà destacant en els pròxims anys. L'eficiència de la combustió i el rendiment del motor són fortament influenciats pel complex procés d'injecció. La injecció directa de gasolina (GDI) augmenta l'estalvi de combustible i complix amb els requisits d'emissions, encara que queda molt potencial per descobrir. Per això, aquest ha sigut objecte d'investigació en els últims anys i, com a conseqüència, d'aquesta Tesi. Aquest treball té com a motivació millorar l'enteniment en el camp del GDI. La complexa natura transitòria de la injecció fa que l'estudi experimental siga força complex. La Mecànica de Fluids Computacional (CFD) sorgeix com una potent alternativa als experiments, i ha sigut adoptada per aquesta investigació. Baix aquest mateix context, es proposa com a objectiu principal d'aquesta Tesi el desenvolupament d'una metodologia predictiva per a la caracterització hidràulica de l'injector, capaç de ser aplicada a les actuals i futures generacions d'injectors GDI (independentment de les característiques de l'injector i del software d'estudi). Una vegada validada, el posterior objectiu és analitzar el comportament de l'esprai. Aquest enfocament busca seguir els passos de la comunitat científica substituint la pràctica experimental. La validació de la metodologia ha sigut duta a terme mitjançant la seva aplicació en dos injectors GDI solenoides multi-orifici. A més, s'han utilitzat dos software CFD comercials: CONVERGE i StarCCM+. La metodologia predictiva se centra en l'estudi del flux intern i el camp proper per tal de caracteritzar hidràulicament l'injector. El problema a tractar es defineix en base a un sistema multi-fàsic en un marc Eulerià i considerant un únic fluid. El tractament del fluid multi-fàsic es realitza mitjançant l'aproximació Volume-of-Fluid (VOF). A més, s'utilitza el Homogeneous Relaxation Model (HRM) per tal de considerar l'intercambi de massa entre les fases líquida i vapor degut als fenòmens de cavitació i flash boiling. La turbulència s'ha tractac a través dels enfocaments Reynolds-Averaged Navier-Stokes (RANS) i Large Eddy Simulations (LES). Pel que fa a l'estudi del fluix extern, s'ha adoptat el Discrete Droplet Model (DDM). Sent conscients que el comportament l'atomització i l'esprai estan influenciats per la geometria de la tovera, l'estratègia d'acoblament del flux intern i extern complementa les anàlisis. S'han adoptat els enfocaments d'acoblament unidireccional i mapejat, utilitzant com a paràmetres d'entrada les dades del flux intern obtingudes amb la validada metodologia. Aquesta Tesi aporta una nova i valuosa metodologia predictiva amb una elevada precisió a l'hora de caracteritzar el procés d'injecció en comparativa amb dades experimentals. És directament transferible a diversos codis de càlcul així com aplicable a injectors amb característiques dispars sense perjudicar les exigències del model. La correcta caracterització del flux intern ha permès utilitzar les dades obtingudes per tal d'analitzar el comportament de l'esprai, eliminant la necessitat d'emprar dades experimentals. Els resultats obtinguts d'aquest estudi capturen el comportament macroscòpic de l'esprai amb una precisió comparable als experiments. Encara que queden molts reptes per afrontar, aquesta Tesi aporta un important avanç al camp del GDI. La ruptura prové del desenvolupament i ús d'una metodologia completament predictiva, que substitueix els experiments requerits i així contribueix a una millor i més ampla visió de la física del procés d'injecció. / [EN] Concerns about climate change, availability of fuel resources and the high demand for vehicles, have led governments to regulate the level of pollution emitted by engines into the atmosphere. There is a strong desire to adopt renewable and sustainable energy sources. However, the substitution of liquid fuels derived from petroleum will not emerge easily, quickly or economically, and Internal Combustion Engines (ICE) will continue to excel for the next few years. Combustion efficiency and engine performance are strongly influenced by the complex fuel injection process. Gasoline Direct Injection (GDI) strategies increase fuel economy and meet emission requirements, although many challenges remain, which has therefore been one of the main research objectives in recent years and of this Thesis. The present research aims to provide a better understanding in the field of GDI. The transient and complex nature of the injection process makes the experimental study of GDI quite challenging. Therefore, Computational Fluid Dynamics (CFD) emerges as a powerful alternative adopted for this research. In this context, the main objective of the present Thesis is to develop a predictive methodology capable of being applied to current and future generations of GDI injectors, regardless of the injector features and the software employed, for the hydraulic characterization of the injector. Once validated, the subsequent goal is to employ the obtained results to analyze the behavior of the spray downstream of the injector. The approach attempts to follow the footsteps of the research community to avoid experimental practice. The predictive methodology has been validated through its application to two multi-hole solenoid GDI injectors with different features. In addition, the mentioned methodology has been evaluated using diverse commercial software: CONVERGE and StarCCM+. The methodology focuses on the study of the internal and near-field flow to hydraulically characterize the injector. So the problem to be addressed is a multi-phase system, performed in an Eulerian framework, modeled through a single-fluid approach. The multi-phase flow is treated by means of the Volume-of-Fluid (VOF) approach. Homogeneous Relaxation Model (HRM) is employed to consider the mass exchange between liquid and vapor fuel phases, due to cavitation and flash boiling. The turbulence treatment has been performed from both Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES) approaches. Regarding the external flow study, the Discrete Droplet Model (DDM) has been adopted. In addition, being aware that atomization and spray behavior is greatly influenced by the nozzle geometry, the coupling strategy of the internal and external flow complements the analyses. One-way coupling and mapping approaches have been adopted, using as input parameters the internal flow data obtained from the already validated methodology. Accordingly, this Thesis provides a new and valuable predictive methodology, which has demonstrated a high accuracy in characterizing the flow behavior during the injection process through comparison with experimental data. It has also proven to be directly transferable to different CFD software and applicable to injectors with dissimilar characteristics without compromising the requirements of the model. The correct internal flow characterization has made it possible to employ the obtained data to analyze the spray patterns, which eliminates the need to consider experimental data. The outcomes of this study macroscopically capture the jet behavior with an accuracy comparable to experiments under different operating conditions. Although there are still many challenges to face, the present Thesis brings a breakthrough in the field of GDI. The quantum leap arises from the development and use of a fully predictive methodology, allowing to avoid most experiments to contribute to a greater and broader vision of the injection process physics. / María Martínez García has been founded through a grant from the Government of Generalitat Valenciana with reference ACIF/2018/118 and financial support from the European Union. These same institutions, Government of Generalitat Valenciana and the European Union, supported through a grant for pre-doctoral stays out of the Comunitat Valenciana with reference BEFPI/2020/057 the research carried out during the stay at Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, ETH Zurich, Switzerland. Special gratitude from the author to both institutions, Government of Generalitat Valenciana and the European Union, for making this dream possible / Martínez García, M. (2022). Computational Study of the Injection Process in Gasoline Direct Injection (GDI) Engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/185180 / TESIS

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