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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.
21

Análise de capacidade do lado aéreo de aeroportos baseada em simulação computacional: aplicação ao Aeroporto de São Paulo - Congonhas. / Airport land side capacity analysis based on computer simulation: application to São Paulo - Congonhas Airport.

João Carlos Medau 20 June 2011 (has links)
O tráfego aéreo brasileiro aumentou sensivelmente nos últimos anos e tem previsões de aumento acima da média mundial para as próximas duas décadas, chegando a 7,3% ao ano. Por outro lado, importantes aeroportos brasileiros já apresentam sinais de congestionamento e políticas de restrição são necessárias para manter os níveis de serviço oferecido às aeronaves e passageiros acima de um limite mínimo aceitável. Este trabalho apresenta uma metodologia baseada em modelos de simulação para analisar a capacidade do lado aéreo de aeroportos. Seu propósito é determinar o fluxo máximo de tráfego, mantendo o nível de serviço acima de um valor pré-definido, levando a atrasos aceitáveis para aeronaves aguardando na fila para decolagem. Para desenvolver o estudo, foi utilizado o software Visual SIMMOD e a metodologia apresentada foi aplicada ao Aeroporto de São Paulo Congonhas. Os resultados das simulações mostram que o aeroporto está saturado, com um volume de tráfego que leva a um nível de serviço inadequado. Para atingir um nível de serviço adequado, uma redução de tráfego é necessária. Outros cenários de simulação mostram que o nível de serviço pode ser melhorado com mudanças em procedimentos de controle de tráfego aéreo, envolvendo separações nas decolagens e aproximações, e também com a substituição de aeronaves turbo hélices por jatos. / The Brazilian air traffic has increased significantly in recent years and is expected to increase above the world average for the next two decades, reaching 7,3% per year. Furthermore, major Brazilian airports are already showing signs of congestion and restriction policies are necessary to keep the level of service (LOS) offered to passengers and aircraft above a minimum acceptable. This work presents a methodology based on simulation models to analyze the capacity of the airside of airports. Its purpose is to determine the maximum flow of traffic while keeping LOS above a minimum level, leading to acceptable delays for aircraft waiting in line for takeoff. To develop the study, Visual SIMMOD software was used and the proposed methodology was applied to Sao Paulo Congonhas Airport. The simulation results show that the airport is saturated with a volume of air traffic that leads to an inadequate LOS. To achieve an adequate LOS, a reduction in traffic is needed. Other simulation scenarios show that the LOS can be improved with changes in ATC procedures involving separations in takeoffs and approaches, and also the replacement of turbo prop aircraft by jets.
22

An empirical investigation of dynamic capabilities at the individual level : the context of new service development

Banjongprasert, Jantima January 2013 (has links)
This paper extends the dynamic capabilities (DCs) perspective into the study of new service development (NSD). Drawing from both the DCs view and the NSD perspective, this paper explores theoretically and examines empirically the associations between four core dynamic capability components: adaptive capabilities, absorptive capabilities, arranging capabilities and administration capabilities (4As capabilities) exercised in the process of NSD. DCs have been argued to reside at different levels of organization. Thus far enormous research has focused on organizational level of DCs. Many studies has recognized the importance of DC at micro/individual level (e.g. Teece, 2007; Rothaermel and Hess, 2007), yet research relating to DC at the individual level of organizations is still lacking. Hence, this study focuses on developing and empirically validating an appropriate measurement scale for micro-level DCs. The majority of NSD research has concentrated on the financial service sector; however, the hotel industry, one of the global largest industries, has not been well investigated (Ottenbacher, 2007). The study addresses its research objectives through an empirical investigation adopting both qualitative interviews and a quantitative survey in the hotel sector. This entailed a large quantitative pilot study (433 respondents) and a full-scale survey of hotel sector employees (1,079 respondents) in Thailand. The results, analysed through multiple regression analysis, show positive impact of 4As capabilities applied in different NSD activities on the NSD outcomes. The research findings provide guidance to managers as to how NSD performance is influenced by DCs exercised during the NSD process. The theoretical and managerial implications of this research are articulated.
23

Investigation of commuter's perceptions towards the implementation of the Bus Rapid Transit (BRT) System: A case study of the BRT System in Polokwane Municipality, Limpopo Province, South Africa

Maluleke, Rivoningo Getrude 21 September 2018 (has links)
MURP / Department of Urban and Regional Planning / The study investigated commuters’ perceptions towards the implementation of bus rapid transport (BRT) system in Polokwane Local Municipality. This was achieved through determining the commuters’ perceptions of the implementation phases of Polokwane BRT. The assessment considered whether the implementation of the Polokwane BRT meets commuters’ travel needs and preferences with respect to the operational characteristics. The study used the stated preference and checklist technique to collect data. Questionnaires were spatially distributed per settlement cluster, targeting the general commuters. Data was also collected through interviews with the company implementing the system and the Polokwane municipal officials. The study was based on a comparison of two scenarios, which are: “protraction of public transport system without BRT and a combination of both public transport and the BRT system”. The collected data was analysed using Scenario-Based Analytical Approach (SBAA), with the aid of Statistical Package for Social Sciences (SPSS) and Microsoft Excel software. The collected data was represented and interpreted using both quantitative and qualitative data presentations formats. The study noted that commuters’ travel needs were limited to comfort, time, fare (affordability), safety and security. The results revealed that the methods used to introduce the implementation of BRT system influenced the perceptions of commuters towards the system. Most of survey respondents (55%) were not aware of BRT system implementation, while (56%) indicated that the methods used were extremely ineffective. Furthermore 43% of the survey respondents were not willing to shift from the public transport to use the BRT system. Therefore, many of the survey respondents (52%) negatively perceived and associated the system with negative transport changes within the Municipality. However, it was also established that the operation of the system within the municipality would attract (77%) commuters towards public transportation such as BRT system, only if the system incorporates commuters’ preferred operational characteristics. On the other hand, the scenarios revealed that without the intervention of BRT system, the municipality is likely to continue experiencing transport problems, although there are also challenges associated with the implementation of BRT system. The use of effective and familiar methods of communication, integrating the system with existing modes of transport, development densification, provision of mixed land use and transit oriented development along BRT corridors and BRT routes extensions to residential and socio-economic areas, are some of the recommendations in support of the BRT system. / NRF
24

Initial Drug Court Risk Assessment Scores and Probationers' Completion of Drug Court Programs

Atkins, Carina T 01 January 2018 (has links)
Drug offenders continue to cost citizens and governments money, while drug courts attempt to rehabilitate offenders and reduce recidivism. The Level of Service Inventory-Revised (LSI-R) is a risk assessment tool used by courts and probation offices to determine needs and risks of offenders, and often determine levels of supervision. The purpose of this quasi experimental study was to determine if there is a statistically significant association between the initial LSI-R scores of offenders entering drug courts and their successful completion of the drug court program. Therapeutic jurisprudence theory, the theoretical framework for this study, suggests that the courts and the law are therapeutic to people and that drug treatment will promote positive behavior changes for the offenders. Data for this study were acquired from a database provided by a Kansas drug court, including initial LSI-R scores, completion records, and demographics of 210 drug court participants. A one-way ANOVA was used to test the hypotheses. Significant statistical results were found, indicating that drug court success was positively associated with the LSI-R score. The study may lead to social change by providing information about participants, most likely to benefit from drug court programs, which will save governments money and make room in the programs for more successful candidates, thus producing more productive citizens in the community.
25

Pedestrian Dynamics: Modeling and Analyzing Cognitive Processes and Traffic Flows to Evaluate Facility Service Level

Lee, Hohyun 09 December 2011 (has links)
Walking is the oldest and foremost mode of transportation through history and the prevalence of walking has increased. Effective pedestrian model is crucial to evaluate pedestrian facility service level and to enhance pedestrian safety, performance, and satisfaction. The objectives of this study were to: (1) validate the efficacy of utilizing queueing network model, which predicts cognitive information processing time and task performance; (2) develop a generalized queueing network based cognitive information processing model that can be utilized and applied to construct pedestrian cognitive structure and estimate the reaction time with the first moment of service time distribution; (3) investigate pedestrian behavior through naturalistic and experimental observations to analyze the effects of environment settings and psychological factors in pedestrians; and (4) develop pedestrian level of service (LOS) metrics that are quick and practical to identify improvement points in pedestrian facility design. Two empirical and two analytical studies were conducted to address the research objectives. The first study investigated the efficacy of utilizing queueing network in modeling and predicting the cognitive information processing time. Motion capture system was utilized to collect detailed pedestrian movement. The predicted reaction time using queueing network was compared with the results from the empirical study to validate the performance of the model. No significant difference between model and empirical results was found with respect to mean reaction time. The second study endeavored to develop a generalized queueing network system so the task can be modeled with the approximated queueing network and its first moment of any service time distribution. There was no significant difference between empirical study results and the proposed model with respect to mean reaction time. Third study investigated methods to quantify pedestrian traffic behavior, and analyze physical and cognitive behavior from the real-world observation and field experiment. Footage from indoor and outdoor corridor was used to quantify pedestrian behavior. Effects of environmental setting and/or psychological factor on travel performance were tested. Finally, adhoc and tailor-made LOS metrics were presented for simple realistic service level assessments. The proposed methodologies were composed of space revision LOS, delay-based LOS, preferred walking speed-based LOS, and ‘blocking probability’.
26

Fleet Optimization and Failure Probability of Winter Maintenance Routes

Miller, Tyler Matthew January 2017 (has links)
No description available.
27

A Framework for Monitoring Performance-Based Road Maintenance

Pinero, Juan Carlos 10 December 2003 (has links)
In the late 1980s and early 1990s few transportation agencies around the world considered performance-based specifications as an alternative to improve the efficiency of the services provided to the public. These initiatives are better known as Performance-Based Road Maintenance (PBRM). PBRM calls for performance-based work, in which a desired outcome is specified rather than a material or method. This type of specification promises to be an excellent tool to improve government efficiency in maintaining transportation networks; however, without proper monitoring, it could likely yield adverse outcomes. Since PBRM is relatively new, the availability of reliable and comprehensive sets of guidelines to evaluate the effectiveness and efficiency of this type of specifications in the roadway maintenance arena is limited. Transportation agencies currently rely on criteria and procedures they have had developed from their traditional methods used to evaluate performance. Unfortunately, some of these procedures cannot appropriately assess the benefits, if any, accrued by the government as a result of implementing performance-based specifications for the maintenance of the roadway system. This research presents the development of a framework for monitoring PBRM more comprehensively and accurately. The framework considers the assessment of five main areas -- Level of Service Effectiveness, Cost-Efficiency, Timeliness of Response, Safety Procedures, and Quality of Services -- in order to guarantee the comprehensiveness and reliability of the evaluation process. The major contribution of this framework is to provide transportation agencies with guidelines for evaluating the effectiveness and efficiency of PBRM as an alternative delivery method to maintain and preserve the roadway system. / Ph. D.
28

A Preliminary Examination of Data Envelopment Analysis for Prioritizing Improvements of a Set of Independent Four Way Signalized Intersections in a Region

Kumar, Manjunathan 28 January 2003 (has links)
Evaluation of critical transportation infrastructure and their operation is vital for continuous evolution to meet the growing needs of the society with time. The current practice of evaluating signalized intersections has two steps. The first is to determine the level of service at which the intersection is performing. Level of Service (LOS) is based on the average delay per vehicle that gets past the particular intersection under consideration. The second step is to do a capacity analysis. This considers the number of lanes and other infrastructure related factors and also includes the influence of the control strategies. The above-described procedure evaluates any one intersection at a time. It is necessary to compare and rank a given set of intersections for planning purposes such as choosing the sites for improvements. The research work presented in this thesis demonstrates how Data Envelopment Analysis (DEA) can be used as a tool to achieve the purpose of comparing and ranking a given set of comparable intersections. This study elaborates on various ways of representing different characteristics of an intersection. The demonstration has been restricted to four way signalized intersections. The intersections that were used for demonstration as part of this research were created in a controlled random fashion by simulation. / Master of Science
29

Improvements to The Global Oceanic Model and Performance Assessment of The North Atlantic Organized Track System

Liang, Yanqi 05 September 2017 (has links)
This thesis presents a performance assessment of flight operations in the North Atlantic Organized Track System (OTS) using the Global Oceanic Model. The main contributions of the study are: a) improvements to the logic of the Global Oceanic Model; b) prediction of benefits among various aircraft separation minima and operational policies to assign flights to tracks in the OTS system; and c) forecast of OTS traffic over North Atlantic from 2020 to 2040. The preliminary results show that a concept of operation with longitudinal separation minima of 15 nm and information of the flight cost matrix provides average fuel savings of 93 kilograms per flight using 2020 traffic. The fuel savings increase to 170 kilograms per flight using traffic levels expected in the year 2040. A new operational track assignment routine is developed and it could save around 40 kilograms per flight compared with the current concept of operations. The study results show a shortage of capacity of the Organized Track System in the future. The analysis shows that the OTS configuration used today and in 2020 is unable to accommodate the traffic projected in 2040. The analysis concludes that more tracks will be needed to maintain an acceptable level of service. / MS / The North Atlantic Organized Track System (OTS) are directional tracks for aircraft to fly between North America and Europe. This thesis presents a performance assessment of flight operations in the North Atlantic using a computer simulation model -- Global Oceanic Model. The main contributions of the study are: a) improvements to the logic of the Global Oceanic Model; b) prediction of benefits among various aircraft separation minima and operational policies to assign flights to tracks in the OTS system; and c) forecast of OTS traffic over Atlantic from 2020 to 2040. The preliminary results show that the predicted average fuel savings in the year 2020 are 93 kilograms per flight when aircraft are separated 15 nm longitudinally and assigned to tracks based on the flight cost matrix. The average fuel savings increase to 170 kilograms per flight using traffic levels expected in the year 2040. Additionally, a new operational track assignment routine is developed and it could save around 40 kilograms per flight compared with the current concept of operations. In conclusion, the Organized Track System configuration used today may be unable to accommodate the traffic projected in the year 2040. The shortage of capacity of the OTS indicates that more tracks will be needed to maintain an acceptable level of service.
30

Percepção dos usuários sobre a qualidade de serviço em rodovias / Users\' perception of quality of service at highways

Paiva, Artur Piatti Oiticica de 11 August 2015 (has links)
Com o intuito de fornecer subsídios para adaptar o HCM ao cenário brasileiro, propõe-se um método que se baseia na percepção dos usuários sobre a qualidade de serviço em rodovias, para estimar os limites de densidade que delimitam os níveis de serviço. A justificativa é que o conceito de nível de serviço considera a qualidade de serviço com base na percepção dos usuários, mas os limites entre os níveis de serviço em rodovias definidos no HCM não considera a opinião dos usuários. Esse método baseia-se num questionário online para coletar as informações necessárias para estimar os limites entre os níveis de serviço por uma análise de regressão logística. No método proposto, a percepção dos usuários sobre a qualidade de serviço é medida através de uma escala contínua e as condições operacionais são mostradas através de vídeos obtidos com um simulador microscópico de tráfego. Um experimento piloto foi realizado para testar o questionário e o método de análise propostos. As variáveis operacionais utilizadas no experimento piloto foram percentual de veículos pesados, velocidade média e concentração veicular. Os resultados desse experimento piloto foram usados para refinar o questionário e mostraram que, dentre as consideradas, a densidade foi a medida operacional que mais influiu na qualidade de serviço percebida pelos respondentes. Por meio do experimento piloto, foi possível estimar o tamanho do questionário e a duração dos vídeos. O método proposto pode ser aplicado para obter os limites entre os níveis de serviço com base na percepção do usuário, no Brasil ou em qualquer outro país, uma vez que um simulador microscópico devidamente calibrado para refletir as condições operacionais locais esteja disponível. / This thesis proposes a method to estimate thresholds for levels of service based on the users\' perception of the quality of service on highways. Whereas the level of service concept includes the users\' perception of the quality of service among the aspects that should be taken into consideration, the level of service criteria used in the highway chapters of the HCM were defined without taking into acc ount the users\' opinion. The proposed approach uses an online questionnaire to obtain the data needed to estimate the thresholds between levels of service, which are then calculated using logistic regression. In the proposed method, the users\' perception of the quality of service is measur ed using a continuous scale and the operating conditions are shown by means of short videos created using microscopic traffic simulation of predetermined scenarios on a virtual highway. By using simulation to create scenarios, it is possible to control all operational variables, covering all cond itions from very low flow to capacity, and, at the same time, to generate a video from the driver\'s point of view. A pilot experiment was used to validate the questionnaire and the method adopted to estimate level of service thresholds. The operational variables used in this pilot experiment included truck percent, average travel speed and density. The results of the pilot experiment were used to refine the questionnaire and have shown that density is the operational variable that has the greatest influence on the users\' perception of the quality of service. The pilot experiment results also defined the number and the length of the videos to be shown to respondents. Despite its creation to support the adaptation of the HCM to Brazil, the proposed method could be applied to any other location, if a microscopic traffic simulator calibrated to represen ttraffic flow on local highways is available.

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