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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.
1

Using Deep Reinforcement Learning For Adaptive Traffic Control in Four-Way Intersections

Jörneskog, Gustav, Kandelan, Josef January 2019 (has links)
The consequences of traffic congestion include increased travel time, fuel consumption, and the number of crashes. Studies suggest that most traffic delays are due to nonrecurring traffic congestion. Adaptive traffic control using real-time data is effective in dealing with nonrecurring traffic congestion. Many adaptive traffic control algorithms used today are deterministic and prone to human error and limitation. Reinforcement learning allows the development of an optimal traffic control policy in an unsupervised manner. We have implemented a reinforcement learning algorithm that only requires information about the number of vehicles and the mean speed of each incoming road to streamline traffic in a four-way intersection. The reinforcement learning algorithm is evaluated against a deterministic algorithm and a fixed-time control schedule. Furthermore, it was tested whether reinforcement learning can be trained to prioritize emergency vehicles while maintaining good traffic flow. The reinforcement learning algorithm obtains a lower average time in the system than the deterministic algorithm in eight out of nine experiments. Moreover, the reinforcement learning algorithm achieves a lower average time in the system than the fixed-time schedule in all experiments. At best, the reinforcement learning algorithm performs 13% better than the deterministic algorithm and 39% better than the fixed-time schedule. Moreover, the reinforcement learning algorithm could prioritize emergency vehicles while maintaining good traffic flow.
2

Strategy-specific Differentiation in Response to Resources and Drivers of Spring Migration Phenology in Rocky Mountain Elk

Crews, Storm 01 August 2023 (has links) (PDF)
Elk (Cervus canadensis) are known to exhibit high movement strategy diversity compared to other ungulate species. Most elk populations are migratory or partially migratory, presenting unique conservation and management challenges. For example, successful maintenance of multiple seasonal ranges and connectivity between them is necessary to conserve populations with migratory behaviors. Further study of the structure and maintenance of movement strategy diversity within partially migratory populations is needed to assist management and refine fundamental ecological theory. Improved understanding of the determinants of elk migratory timing is also important, with the dynamics of significant drivers likely to shift under future climate change and anthropogenic expansion. I investigated strategy-specific environmental responses in multiple Rocky Mountain elk populations and found evidence for a differentiation in resource use and selection among sympatric individuals using differing strategies. This result suggests a potential mechanism for the reduction of intraspecific competition and heightened population densities in partially migratory herds. However, the nature and strength of differentiation was found to be context dependent. I found that elk avoid human development and seasonally select for forage quantity over quality at relatively fine scales, highlighting some consistent selection responses as well. Overall, this analysis demonstrated intrapopulation response heterogeneity in partially migratory elk populations and characterized strategy-specific patterns of resource use and selection.I investigated how spring migratory timing and duration relate to spatiotemporal forage dynamics, finding that departure dates are affected by vegetative green-up along migratory corridors, while the duration of migration is influenced by the timing of green-up at the summer range. These results highlight a form of migratory plasticity, wherein migrants modulate both their departure date and the duration of their migration as a function of vegetative phenology. Additionally, I present a framework to quantify optimality of migratory movements in relation to peak forage conditions. On average, elk were found to exhibit high optimality, with interindividual variability along a gradient. My findings suggest a variety of responses to green-wave phenology, with optimality of movements differing as a function of individual and study area. This work contributes to the growing understanding of migratory plasticity as multidimensional and highlights the variability of migratory behavior within and among populations.
3

Ny grön våg till följd av pandemin? : En undersökning om hur coronapandemin påverkat boendepreferenser och intresset för landsbygden / New green wave as a result of the pandemic? : A study of how the corona pandemic has affected housing preferences and the interest of rural areas

Edwall, Frida, Ida, Kullander January 2022 (has links)
Syftet med studien är att undersöka hur coronapandemin påverkat människors boendepreferenser, vilka effekter det fått på intresset för att bo på landsbygden och om trenden för en ny grön våg uppstått, likt den på 1970-talet. Detta för att erhålla ett bredare perspektiv på hur pandemin påverkat samhället, med utgångspunkt i betydelsen av hemmets egenskaper och närmiljö. Studien besvarar följande frågor: ● Hur har boendepreferenserna i Värmland förändrats under coronapandemin? ● Har coronapandemin blivit ett startskott för en ny utflyttningstrend till landsbygden, likt den gröna vågen som inträffade under 1970-talet? Studien grundar sig primärt i en kvantitativ metod i form av en enkätundersökning riktad till urvalsgruppen Värmlandsbor över 18 år, för att undersöka frågeställningarna. Den bygger dessutom på en sekundäranalys av kommentarer till P4 Värmland Sveriges Radios Facebookinlägg om varför folk väljer att bo kvar på glesbygden. Perioden som studerats har avgränsats till åren 2020 och 2021. Utifrån studiens presenterade litteraturbakgrund visar analysen av det empiriska materialet påökad attraktivitet för landsbygden och mindre orter. Större boyta har efterfrågats i högre grad under pandemiåren än tidigare. Även betydelsen av närhet till natur- och grönområden samt tillgång till trädgård, uteplats eller balkong har ökat betydligt under coronapandemin, jämfört med innan. Samtidigt har viljan att bo citynära sjunkit. Under 1970-talets gröna våg var politiken det främsta motivet till utflyttning till landsbygden. Idag är det snarare längtan till naturen och lugnet som ligger bakom, men också att flytta närmare familj och vänner som redan bor där. Dessutom har intresset för odling ökat under pandemin, vilket delvis lockar till ett liv på landsbygden. Det finns även en trygghetsfaktor i att odla sin egen mat och vara självförsörjande i osäkra tider, såsom under coronapandemin. Övergången till distansarbete har för många gjort det möjligt att ta steget att flytta till landsbygden, eftersom arbetsplatsen inte längre kräver fysisk närvaro i samma utsträckning som innan pandemin. Det har dessutom visat sig att majoriteten vill fortsätta arbeta hemifrån i viss mån i även i framtiden. Det är dock för tidigt att säga om trenden kommer bestå. / The purpose of this study is to investigate how the corona pandemic has affected people's housing preferences, how it has affected the interest in living in rural areas and whether the trend for a new green wave has emerged, similar to the one that occurred in the 1970s. This to obtain a broader perspective on how the pandemic has affected society, based on the valuation of different characteristics of homes and their local environment. This study has answered the following questions: ● How housing preferences in Värmland have changed during the corona pandemic? ● Has the corona pandemic become the starting point for a new emigration trend to rural areas, like the green wave that occurred in the 1970s? The study is primarily based on a quantitative method in the form of an internet-based survey aimed at the selection group of residents in Värmland over the age of 18, to investigate the research questions. The study is also based on a secondary analysis of comments to a Facebook post published by the Swedish radio channel P4 Värmland Sveriges Radio about why people choose to stay in rural areas. The examined period has been limited to the years 2020 and 2021. Based on what is presented in the literature background, the analysis of the empirical material shows increased attractiveness for rural areas and smaller towns. Larger living space has been in greater demand during the pandemic years than before. The importance of closeness to nature and green areas as well as access to garden, patio or balcony increased significantly during the corona pandemic, compared with before. At the same time, the desire to live close to a city has declined. During the green wave of the 1970s, political motives were the main reason for moving to rural areas. Today, it is rather the longing for nature and tranquillity that lies behind the decision, but also to move closer to family and friends who already live there. Moreover, the interest in cultivation has increased during the pandemic, which in part attracts people to the countryside. In addition, there is a security factor in growing your own food and being selfsufficient during uncertain times, such as during the corona pandemic. The transition to teleworking has made it easier for people to take the step of moving to rural areas, as many workplaces no longer require physical presence to the same extent as before the pandemic. Besides, the majority want to continue working from home to some extent in the future as well. However, it is too early to say whether the trend will continue.
4

‘Enacting change for a different future’ : An exploration of the practices and lifestyle of the new green wave

Mattsson, Anny January 2023 (has links)
This thesis departs from an understanding that humanity stands on the cusp of a global crisis, caused to a large degree by the lifestyle choices of humans. Therefore, posing the argument that it is changes in human action, behaviour and lifestyles that are needed to ensure that the development doesn’t continue on its current path. This thesis therefore aimed to explore the new green wave lifestyle, which pertains to people who are choosing to face these challenges head on by actively changing and adopting a self-sustainable lifestyle. To explore this aim, the study utilised a theoretical framework consisting of two main concepts, social practice theory and the concept of lifestyles. The thesis used semi-structured interviews to gather data from individuals who actively made the active choice to change their way of living and adopt a self- sustainable lifestyle. The results show that the new green wavers rely heavily on inspiration from others to make their lifestyle change. This meant that being able to see and be inspired by other people’s alternative ways of living was integral for them to even comprehend the possibility of living a different lifestyle. The results also show that in enacting their new green wave lifestyle the participants chose to partake in alternative practices or enacting practices in a different way compared to how they conventionally might be enacted. Additionally, the results show that the new green wavers encounter challenges in enacting their lifestyle, which relates to a lack of available knowledge of how alternative practices are to be enacted but also the challenges posed by society in terms of legislation and bureaucracy.
5

Reducción de la congestión vehicular a través de la implementación de la Ola Verde en la Av. Caminos del Inca en el tramo comprendido entre Jr. Batallón Callao Norte y Jr. Cádiz en el distrito de Surco / Reduction of vehicular congestion through the implementation of the Green Wave on the Caminos del Inca Avenue in the stretch between Batallón Callao Norte street and Cadiz street in the district of Surco

Campomanes Campomanes, Alfredo Jorge, López Olivera, Joel Moisés 15 January 2019 (has links)
El congestionamiento vehicular es uno de los problemas que más se agudiza en la ciudad de Lima. Este problema se ve reflejada en casi todas las calles y avenidas principales de la ciudad, debido a factores como el incremento del parque automotor que hacen colapsar la capacidad de la infraestructura y dejan en desuso la gestión de tránsito para la que fue diseñada; dicho de otra manera, el incremento del flujo vehicular ocasiona gran congestión, largas colas, prolongadas demoras y niveles de servicio deficientes. La zona de estudio a tratar se encuentra en el distrito de Surco y la vía intervenida es la avenida Caminos del Inca en el tramo del jirón Batallón Callao hasta el jirón Cádiz atravesando avenidas importantes como Velazco Astete e Higuereta. Esta avenida es una de las más transitadas del distrito de Surco a causa de los centros comerciales, institutos, universidades, entre otros, que se encuentran cercanas a esta importante arteria vial. Por ello, este trabajo de tesis tiene como objetivo principal disminuir la congestión vehicular de la Av. Caminos del Inca en el tramo de estudio y mejorar los niveles de servicio en sus intersecciones con la implementación de la ola verde a través del modelamiento y simulación en el software Synchro 8. Para la elaboración de este trabajo se recopilaron datos de campo como el aforo vehicular para determinar la hora punta y el volumen horario de máxima demanda vehicular, asimismo se realizó la medición de los ciclos semafóricos y sus faces en un día típico de la semana. Con todos estos datos compilados en el trabajo de campo, se obtuvieron los grados de saturación y los niveles de servicio actuales para que posteriormente sean evaluadas a fin de implementar la ola verde y optimizar el tránsito. Finalmente, con la implementación de la ola verde y las modificaciones de gestión de tráfico se obtuvieron mejoras notables como optimización de los niveles de servicio en las intersecciones, por ejemplo, en la intersección N° 01 pasó de C a B, en la N° 02 de F a D, en la N° 03 de C a B y en la N° 04 de C a B; asimismo, las esperas en las intersecciones disminuyeron favorablemente como se indica a continuación, en la intersección N° 01 Bajó de 20.1s a 16.7s, en la N° 02 de 332.2s a 35.3s, en la N° 03 de 239.9s a 11.4s y en la N° 04 de 37.0s a 6.3s; de igual forma, el tiempo de recorrido de un punto extremo, intersección N° 01, al otro, Intersección N° 04, mejoró considerablemente de 6 minutos y 30 segundos aproximadamente a 1 minuto y 28 |segundos debido a la sincronización progresiva del color verde de los semáforos en cada intersección. / Traffic congestion is one of the most acute problems in the city of Lima. This problem is reflected in almost all the streets and main avenues of the city, due to factors such as the increase in the vehicle fleet that collapses the capacity of the road infrastructure and leaves the traffic management for which it was designed in disuse; In other words, the increase in the flow of vehicles causes great congestion, long queues of vehicles, prolonged delays and poor service levels. The study area to be treated is in the district of Surco and the intervened road is the Caminos del Inca avenue in the stretch from Batallón Callao street to Cádiz street crossing important avenues such as Velazco Astete and Higuereta. This is one of most heavily traveled avenue in the district of Surco because of the shopping centers, institutes, universities, among others, that are close to this important traffic artery. Therefore, this thesis work has as main objective to reduce the vehicular congestion of this avenue and improve the service levels of its intersections with the implementation of the green wave through modeling and simulation in the Synchro 8 software. For the elaboration of this research work, field data were collected, such as the vehicle capacity to determine the peak hour and the hourly volume of maximum vehicular demand, as well as the measurement of the traffic light cycles and their faces in a typical day of the week. With all this data compiled in the field work, saturation degrees and current service levels were obtained so that later they can be evaluated in order to implement the green wave and optimize traffic. Finally, with the implementation of the green wave and traffic management modifications, notable improvements were obtained such as optimization of service levels at intersections, for example, at intersection No. 01 it went from C to B, at No. 02 from F to D, in No. 03 from C to B and in No. 04 from C to B; in the same way, the travel time from an extreme point, intersection No. 01, to the other, Intersection No. 04, improved considerably from 6 minutes and 30 seconds approximately to 1 minute and 28 seconds due to the progressive synchronization of the green colour of the traffic lights in each intersection. / Tesis

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