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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

An Experimental Investigation of Supersonic Rectangular Over-Expanded Nozzle of Single and Two-Phase Flows

MOHAMED, ASHRAF ELSAID 18 April 2008 (has links)
No description available.
82

The Power to Promote Justice Program: A Train-the-Trainer Model for the Development of Culturally Competent Teaching Practices Among Secondary Educators

Hairston, Patrece Gabrielle 30 January 2012 (has links)
No description available.
83

SHOCK CORRELATION INVESTIGATION IN A GASEOUS FUELED AXISYMMETRIC SCRAMJET FLOWPATH

Larios-Barbosa, Jaime Omar 23 August 2013 (has links)
No description available.
84

Swords into plowshares: civilian application of wartime military technology in modern Japan, 1945-1964

Nishiyama, Takashi 06 January 2005 (has links)
No description available.
85

Interoperability Study of the European and Chinese Railway Signalling Systems : Case study in Ethiopia / Interoperabilitetsstudie av de europeiska och kinesiska järnvägssignalsystemen : Fallstudie i Etiopien

Tana, Kebron Temedo January 2021 (has links)
The railway industry in Ethiopia has been an important way of communication and transportation for a long time. It is a developing sector with many national plans for future investments. However, the current major corridors of Ethio­-Djibouti and Awash­-Weldiya have interoperability issues due to two different signalling systems being used. Thus, this study was undertaken with the objectives of assessing technical interoperability of the Chinese signalling system (CTCS) and the European signalling system (ETCS), identifying a possible technical solution regarding the interoperability issues, and assessing the economic benefits of a harmonized system. Compatibility of the two signalling systems was analyzed particularly with respect tothe technical configurations by thoroughly investigating each system’s features and making interviews and having discussions with professionals who worked with the two systems. In addition, a life cycle cost analysis of the Ethio­Djibouti signalling system was done with data obtained from Ethiopian Railway Corporation and compared with average life cycle costs of ETCS level 1. After analyzing each system, two possible technical solutions were found to achieve interoperability between the two systems used in Ethiopia currently. The first technical solution is upgrading Ethio­Djiboutirailway line from the current CTCS level 0 to CTCS level 2 to be compatible with the new Awash­Weldiya line which will use ETCS level 1. The second technical solution to make the two systems interoperable is to install ERTMS as an overlay on the existing CTCS level 0 as ERTMS is designed as an overlay system that could be installed on top of an existing national infrastructure and vehicles. However, these technical solutions have to be tested in laboratory and onsite with respect to their practical and economical feasibility. / Järnvägsindustrin i Etiopien har länge varit viktig för kommunikation och transport. Det är en sektor under utveckling med många nationella planer för framtida investeringar. De nuvarande korridorerna i Ethio­Djibouti och Awash­Weldiya har emellertid interoperabilitetsproblem på grund av två olika signalsystem. Detta examensarbete har analyserat kompatibiliteten för de två signalsystemen särskilt med avseende på de tekniska konfigurationerna genom att noggrant undersöka varje systems funktioner och genom intervjuer och diskussioner med yrkesverksamma somhar arbetat med de två systemen. Dessutom genomfördes en livscykelkostnadsanalys av Ethio­Djibouti signalssystemet med den data som erhölls från Ethiopian Railway Corporation. Efter analys av varje system hittades två möjliga tekniska lösningar för att uppnå interoperabilitet mellan de två systemen som används i Etiopien för närvarande. Den första tekniska lösningen är att uppgradera Ethio­Djiboutis järnvägslinje från nuvarande CTCS nivå 0 till CTCS nivå 2 för att vara kompatibel med den nya Awash­Weldiya­linjen som kommer att använda ETCS nivå 1. Den andra tekniska lösningen för att göra de två systemen interoperabla är att installera ERTMS som ett överlägg på det befintliga CTCS­0 signalsystemet, eftersom ERTMS är utformat som ett överläggssystem som kan installeras ovanpå en befintlig nationell infrastruktur. Dessa tekniska lösningar måste dock testas i laboratorium och i fält med avseende på deras praktiska och ekonomiska genomförbarhet.
86

Locomotion: A Cinematic Approach

Rocci, Lisa 06 July 2006 (has links)
The landscape is not static, but perceived dynamically and should be designed for the unique sorts of movement that occur. Within the site of Carpinteria, California's Amtrak train station lies an opportunity to maximize public space through an investigation of those in motion at this place of convergence, including cars, busses, pedestrians, skateboarders, bicyclists, and trains. A cinematic process of design allows for exploration of distinct character movements and resulting unique perceptions of the site in terms of scale, rhythm, texture, color, and perceived desire or needs. These stories are then sculpted onto the land, recording physically threads of speed, moments of pause, and elements of fascination. The "new" station is presented as a movie, unveiling a landscape perceived and created dynamically through the eyes of those in motion. / Master of Landscape Architecture
87

Air Pollution Distribution under an Elevated Train Station (A Case Study of Silom Station in Downtown Bangkok)

Charusombat, Umarporn 01 January 1999 (has links)
To solve traffic congestion in Bangkok, the Bangkok Mass Transit system (BTS) constructed an overhead rail system with 24 stations. The BTS train station, S2, in this study area covers Silom road and obstructs the air pollutant dispersion in a congestion area. The 1: 200 physical model of the buildings along Silom road with the train station, S2, was simulated in this research to determine the air pollutant dispersion in the train station area. A tracer gas (CO₂) was emitted from a simulated line source with emission rates of 0.383, 0.681, 1.293, 2.586, 5.177 and 10.77 mg/min to simulate actual pollutant emission rates. The CO₂ gas was sampled at 55 locations in the model. The Kriging method was used to interpolate the data in the study area. . Emission rates were used to make the difference between measured CO₂ in the model area and ambient CO₂ large enough to be differentiated. Regression Analysis was used to relate analytically the mass emission rate to the CO₂ concentration. The results indicate that the maximum CO concentrations exceed the 30 ppm Bangkok standard along the Southeast side of Silom Road at the passenger platform level. Drivers will acquire more harmful levels of CO than pedestrians at street level, especially near the Southwest end of the train station. NO₂ concentrations do not exceed the standard (0.17 ppm) at street level. The highest predicted VOC is 1.05 ppm. These results may be used in the future for numerical modeling study. / Master of Science
88

Cultivating a Healthy School Environment: Evaluation of a Virginia School Nutrition Training Program

Nelson, Rachel A. 18 May 2020 (has links)
The Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) framework was used to evaluate the impact of the Virginia Department of Education's (VDOE) implementation of the USDA's Team Nutrition training program on Virginia elementary schools from 2017-2020. The VDOE provided training for school nutrition directors (SNDs) at workshops in June 2018 and September 2019 and continued technical assistance to help SNDs improve the school food environment within their divisions. SNDs' perceived support, self-efficacy, and intention to implement changes to the school food environment was measured through pre- and post-training surveys and quarterly check-ins. Implementation was measured using lunchroom environment observations and strategic plans created at the workshops. SNDs representing 83.9% of Virginia elementary students (512,953 students) in 111 divisions attended at least one of the workshops. Within effectiveness, perceived support from cafeteria staff was highest among all stakeholders for both the 2018 and 2019 trainings, though it significantly decreased from before to after the training for both workshops. Average perceived support did not significantly change over time. Self-efficacy was significantly higher following the 2018 training workshop only. The intervention was adopted by 84% of divisions and both intention to implement and actual implementation were highest for strategies related to Farm to School, a VDOE priority. Effectiveness and implementation are expected to improve as it takes up to years for changes to occur in schools. Despite RE-AIM not being part of the initial evaluation plan, 62% of indicators were assessed. With some adaptations to improve effectiveness, the intervention should continue and be expanded. / Master of Science / Interventions to improve the dietary habits of children are often conducted in schools, as most children attend school and children consume up to two meals while at school. USDA's Team Nutrition initiative trains school nutrition staff to serve healthy school meals and provides materials to implement nutrition education for students. The Virginia Department of Education implemented the Team Nutrition program statewide through two training workshops for school nutrition directors (SNDs), June 2018 and September 2019, and technical assistance between the trainings. This study examined the process of implementing the intervention, as well as the outcomes. Overall, 84% of Virginia elementary students were represented by SNDs at the training workshops. SNDs were most likely to intend to implement and implement changes in their divisions related to Farm to School programs and least likely change their culinary skills trainings for staff. It can take up to two years after a training for changes to be implemented in schools, therefore it may be too early to know the full effect of the training. The results showed that the intervention was widely adopted, with 84.1% of divisions in Virginia attending at least one of the training workshops. Although participation was high in-person, less SNDs participated in the intervention activities outside of the trainings. Overall, the intervention was successful in reaching many students and had a small positive effect. With some adaptations to improve the effectiveness, the intervention should continue to be implemented and expanded to the rest of the state.
89

Contribution aux méthodes de conception et de gestion des systèmes énergétiques multi-sources par optimisation systémique : application aux trains hybrides électrique autonomes / Contribution to design methods and management of multi-sources energy system by systemic optimization : application to hybrid electric trains and autonomous

Poline, Marie 28 November 2018 (has links)
En France, il existe deux modes de traction pour les trains : la traction diesel ou la traction électrique. Chaque mode fait face à des problématiques qui lui sont propres. Dans le cas du diesel, les émissions de gaz à effet de serre étant de plus en plus contrôlées, il devient nécessaire de faire évoluer ce type de train vers une solution moins polluante. Dans le cas de la traction électrique, la consommation d’énergie entraine une chute de tension qui peut imposer un ralentissement des trains, empêchant ainsi le développement du trafic. La solution étudiée par la SNCF est l’hybridation des trains (ajout de systèmes de stockage en embarqué).Ces travaux de thèse ont pour objectif de mettre en place une méthode permettant de faire le pré-dimensionnement des systèmes de stockage embarqués dans le train. De plus, afin de tenir compte de l’influence réciproque de la gestion sur le dimensionnement, celle-ci est incluse dans le modèle de dimensionnement. La résolution du modèle global se fait à l’aide d’un algorithme d’optimisation.La méthode a été mise en place sur les deux modes de traction ferroviaire (diesel et électrique) et l’optimisation a été faite avec l’algorithme SQP (Sequential Quadratic Programming). / In France, there are two traction modes for railway: the diesel and electric traction. Each mode has its own issues. For diesel, the increasing control of the greenhouse gas emissions imposes to evolve this type of train to a less polluting solution. For electric traction, the energy consumption creates a voltage drop which can cause a traffic slowdown, which will limit the traffic development. The studied solution by SNCF is the hybridization of the train (adding storage system).Thus, these works have the objective to build a method to do the pre-sizing of storage systems embedded in trains. Moreover, to take into account the mutual influence of the sizing and the energy management, this last one is included in the sizing model. An optimization algorithm solves the global model.The method has been developed for the two traction modes (diesel and electric) and the optimization has been made with SQP algorithm (Sequential Quadratic Programming).
90

A multi-agent based cooperative control model applied to the management of vehicles-trains / Un modèle de contrôle coopératif multi-agent appliqué à la gestion de trains de véhicules

Chen, Bofei 10 February 2017 (has links)
L'utilisation de véhicules individuels est de plus en plus importante dans les centres-villes. Ceci entraîne de nombreux effets secondaires tels que la pollution, l'embouteillage et une augmentation des accidents. Les technologies liées au développement des véhicules intelligents ont pour but de surmonter ces problèmes. Certaines des solutions proposées sont déjà accessibles au grand public, telles que les systèmes de préventions des collisions ou les aides aux maintient dans les files de circulation... Actuellement, de nombreux travaux se concentrent sur la recherche de solutions adaptées et acceptables à ces problèmes et notamment sur la gestion des embouteillages. Les solutions proposées permettent de résoudre le problème du trafic, que ce soit au niveau du système, en se concentrant sur la gestion de feux de circulation ou au niveau individuel en offrant aux véhicules de meilleurs systèmes de contrôle et de perception visant à réduire le temps de réponse et / ou à accroître la capacité des routes.Du point de vue des véhicules, l'une des solutions les plus prometteuses est de regrouper les véhicules en convoi (trains de véhicules ou platoon). Deux principales tendances peuvent être trouvées dans la littérature. D'un côté, les approches globales sont basées sur un référentiel commun, généralement lié au lieu d'évolution des véhicules, et partagé par tous les véhicules du train. Ensuite, chaque véhicule se comporte en prenant en compte cette référence partagée qui peut être soit la trajectoire du premier véhicule du train, soit une trajectoire de référence construite au préalable. La seconde catégorie dite de type approche locale est basée sur les capacités de perception locales des véhicules. Dans ce cadre, certaines méthodes, basées sur des algorithmes de contrôle classiques ou sur des liaisons d'interaction physiques et inter-véhicules, sont développées.Malgré de nombreux travaux sur ce sujet, qui se concentrent principalement sur le contrôle des véhicules individuels, peu d'entre eux considèrent le contrôle de convoi d'un point de vue système de transport. Or, ce point de vue système est particulièrement important lorsque plusieurs convoi doivent partager le réseau routier et se rencontrer à des nœuds critiques tels que carrefours et ronds-points. Cette problématique introduit de nouveaux défis tels que: 1) l'organisation des véhicules en trains de véhicules, 2) les interactions entre les trains de véhicules et 3) les stratégies de partage de l'infrastructure routière efficaces, fiables et sûres. Résoudre ces problèmes permettra alors d'envisager la solution train de véhicules comme un bon candidat pour résoudre les problèmes de flux de trafic au niveau du système de transport.Le but de cette thèse est de proposer une approche basée sur le paradigme multi-agent se focalisant sur les problématiques liées aux intersections entre des trains de véhicules. Ainsi, nous proposons un modèle de contrôle coopératif reposant sur des processus décisionnels multi-niveaux. Ce contrôle permet à la fois de préserver la cohérence et la sécurité de chaque train de véhicule et d'adapter leur comportement de manière à rendre efficace le partage de l'infrastructure. le modèle proposé est divisé en trois niveaux différents: au niveau du train, au niveau véhicule et au niveau composant de la chaîne de contrôle/commande. Cette thèse se focalise principalement sur les deux premiers niveaux. Ainsi, le processus décisionnel du train prend ses informations au niveau des autres trains et de ses constituants et envoi des requêtes au niveau véhicule. Le processus décisionnel au niveau véhicule fusionne les informations locales de sa perception propre et celles fournies par le train et produit des consignes appliquées par le niveau contrôle/commande. Cette thèse étudie également les possibilités de reconfiguration dynamique des trains en utilisant les intersections. / The use of individual vehicles is becoming more and more important in inner cities, leading to many side problems such as traffic jam, air pollution and accidents. Intelligent vehicles have been studied so as to overcome these problems. Some solutions provided by these works are already available to the general public market such as city safety systems, lane assists,... Many research works are focusing on finding suitable and acceptable solutions to these problems and dealing with traffic jam management. The proposal can tackle the traffic jam problem whether on system level or on individual vehicle providing better control and perception systems aimed at reducing time response and/or at increasing the road capacity.On the vehicle side, one promising solutions is vehicles platoons (vehicles-train) making possible a huge reduction of the longitudinal distance between vehicles and thus allowing an increase of roads capacity. Basically, two main trends can be found literature. On one side, global approaches are based on a common reference frame, generally tied to the vehicles playground, shared by all vehicles of the train. Then, each vehicle behaves according to this shared reference which can be either the trajectory of the first vehicle of the train or a reference trajectory built offline. On the other side, local approaches are based on vehicle local perception abilities. Some methods, based on classical control algorithms or physical-inspired and inter-vehicular interaction link, are developed.Despite numerous research works on this subject, which are focusing on individual vehicle control, few of them consider the platoon control solution on the system point of view. However, this system point of view is particularly important when several platoons have to share the road network and meet at critical nodes such as crossroads and roundabouts. This introduces new issues such as (1) how to organize vehicles and trains of vehicle, (2) the interactions between trains of vehicles and (3) the strategies of sharing the road infrastructure efficient, reliable and safe. Solving these problems will then allow considering vehicles-train solution as a good candidate for solving traffic flow issues at transportation system level.The goal of this thesis is to propose an approach, based on multi-agent paradigm, which aims at dealing with systems level issues focusing mainly on intersections between vehicles-trains of vehicles. Thus, we propose a cooperative control system which relies on multi-level decision processes aimed at dealing with the interaction of platoons at road network nodes. This cooperative control system allows both to maintain the coherence and the safety condition of each involved train of vehicles and to adapt each train components behavior so as to make train shared the road, and especially roundabouts and crossroads, efficiently (i.e. without stopping any vehicle). This cooperative control system is divided into three different levels. The global train state is managed at the train-level decision process based on the train level perceptions. The vehicle-level process makes the decision concerning each individual vehicle according to data provided by the train-level and to the interaction between vehicles. Finally, the motor-level process makes the link between the vehicle-level command and hardware level of vehicles. In this thesis, we focus on the train-level and vehicle-level. When encountering, trains exchange information such as one part of their perceptions.Besides the goal of having an efficient approach so as to enable several vehicles-trains to share the road infrastructure, we also strategies to transform the meetings of vehicles-trains at road nodes into reconfiguration spots where trains can reconfigure and recombine.The developed algorithm are tested in simulation so as to obtain proper evaluation of our proposal using suitable indicators.

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