11 research outputs found
Shared Mobility Optimization in Large Scale Transportation Networks: Methodology and Applications
abstract: Optimization of on-demand transportation systems and ride-sharing services involves solving a class of complex vehicle routing problems with pickup and delivery with time windows (VRPPDTW). Previous research has made a number of important contributions to the challenging pickup and delivery problem along different formulation or solution approaches. However, there are a number of modeling and algorithmic challenges for a large-scale deployment of a vehicle routing and scheduling algorithm, especially for regional networks with various road capacity and traffic delay constraints on freeway bottlenecks and signal timing on urban streets. The main thrust of this research is constructing hyper-networks to implicitly impose complicated constraints of a vehicle routing problem (VRP) into the model within the network construction. This research introduces a new methodology based on hyper-networks to solve the very important vehicle routing problem for the case of generic ride-sharing problem. Then, the idea of hyper-networks is applied for (1) solving the pickup and delivery problem with synchronized transfers, (2) computing resource hyper-prisms for sustainable transportation planning in the field of time-geography, and (3) providing an integrated framework that fully captures the interactions between supply and demand dimensions of travel to model the implications of advanced technologies and mobility services on traveler behavior.Dissertation/ThesisDoctoral Dissertation Civil, Environmental and Sustainable Engineering 201
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Modeling Choice Problems with Heterogeneous User Preferences in the Transportation Network
Users of transportation systems need to make a variety of different decisions for their trips in the network, while their objective is to keep the generalized costs of their own trips minimized. In the transportation network, there is a diversity of different factors that can influence the decisions of the users, while the relative importance of these factors varies among the heterogeneous users with different trip purposes. Nonetheless, the cumulative result of the individual decisions of the users seeking to minimize their costs according to their own preferences leads to the user equilibrium condition in which no one can reduce his/her cost by changing his/her decision. In this research, we adapt the concept of the efficient frontier from portfolio theory (Markowitz, 1952) in finance in order to model the bicriterion choice behavior of users with heterogeneous preferences in transportation networks. We show that the efficient frontier has a set of primary properties that remains general in different problems. Thus, the primary properties of the efficient frontier can be employed to analytically model and solve different bicriterion choice problems in transportation.
For the first application, we use these properties to propose an analytical model for the morning commute problem when there is a heterogeneity associated with preferences of the users (Vickrey, 1969; Daganzo, 1985). A dynamic pricing strategy is also proposed to optimize the bottleneck by minimizing the total cost for users. In addition to the morning commute problem, Vickrey’s congestion theory is also shown to have applications in modeling and optimizing the operation of the demand responsive transit (DRT) system with time-dependent demand and state-dependent capacity as queueing systems. The efficiency of the DRT system can be improved by implementing a dynamic pricing strategy. The analytical solution of the morning commute problem can be also extended for modeling and pricing the DRT system when there is a heterogeneity associated with the preferences of the DRT service users.
For another application of the efficient frontier in modeling choice problems in transportation, we propose a traffic assignment model to account for the heterogeneity in sensitivity of the users to travel time reliability in a network under travel time variability. However, the proposed model can have wide applications in modeling the equilibrium condition of different multicriterion choice problems in transportation
Dynamics in Logistics
This open access book highlights the interdisciplinary aspects of logistics research. Featuring empirical, methodological, and practice-oriented articles, it addresses the modelling, planning, optimization and control of processes. Chiefly focusing on supply chains, logistics networks, production systems, and systems and facilities for material flows, the respective contributions combine research on classical supply chain management, digitalized business processes, production engineering, electrical engineering, computer science and mathematical optimization. To celebrate 25 years of interdisciplinary and collaborative research conducted at the Bremen Research Cluster for Dynamics in Logistics (LogDynamics), in this book hand-picked experts currently or formerly affiliated with the Cluster provide retrospectives, present cutting-edge research, and outline future research directions
The Internet of Things and The Web of Things
International audienceThe Internet of Things is creating a new world, a quantifiable and measureable world, where people and businesses can manage their assets in better informed ways, and can make more timely and better informed decisions about what they want or need to do. This new con-nected world brings with it fundamental changes to society and to consumers. This special issue of ERCIM News thus focuses on various relevant aspects of the Internet of Things and the Web of Things
Performance evaluation of future wireless networks: node cooperation and aerial networks
Perhaps future historians will only refer to this era as the \emph{information age}, and will recognize it as a paramount milestone in mankind progress. One of the main pillars of this age is the ability to transmit and communicate information effectively and reliably, where wireless radio technology became one of the most vital enablers for such communication. A growth in radio communication demand is notably accelerating in a never-resting pace, pausing a great challenge not only on service providers but also on researches and innovators to explore out-of-the-box technologies. These challenges are mainly related to providing faster data communication over seamless, reliable and cost efficient wireless network, given the limited availability of physical radio resources, and taking into consideration the environmental impact caused by the increasing energy consumption. Traditional wireless communication is usually deployed in a cellular manner, where fixed base stations coordinate radio resources and play the role of an intermediate data handler. The concept of cellular networks and hotspots is widely adopted as the current stable scheme of wireless communication. However in many situations this fixed infrastructure could be impaired with severe damages caused by natural disasters, or could suffer congestions and traffic blockage. In addition to the fact that in the current networks any mobile-to-mobile data sessions should pass through the serving base station that might cause unnecessary energy consumption. In order to enhance the performance and reliability of future wireless networks and to reduce its environmental footprint, we explore two complementary concepts: the first is node cooperation and the second is aerial networks. With the ability of wireless nodes to cooperate lays two main possible opportunities; one is the ability of the direct delivery of information between the communicating nodes without relaying traffic through the serving base station, thus reducing energy consumption and alleviating traffic congestion. A second opportunity would be that one of the nodes helps a farther one by relaying its traffic towards the base station, thus extending network coverage and reliability. Both schemes can introduce significant energy saving and can enhance the overall availability of wireless networks in case of natural disasters. In addition to node cooperation, a complementary technology to explore is the \emph{aerial networks} where base stations are airborne on aerial platforms such as airships, UAVs or blimps. Aerial networks can provide a rapidly deployable coverage for remote areas or regions afflicted by natural disasters or even to patch surge traffic demand in public events. Where node cooperation can be implemented to complement both regular terrestrial coverage and to complement aerial networks. In this research, we explore these two complementary technologies, from both an experimental approach and from an analytic approach. From the experimental perspective we shed the light on the radio channel properties that is hosting terrestrial node cooperation and air-to-ground communication, namely we utilize both simulation results and practical measurements to formulate radio propagation models for device-to-device communication and for air-to-ground links. Furthermore we investigate radio spectrum availability for node cooperation in different urban environment, by conductive extensive mobile measurement survey. Within the experimental approach, we also investigate a novel concept of temporary cognitive femtocell network as an applied solution for public safety communication networks during the aftermath of a natural disaster. While from the analytical perspective, we utilize mathematical tools from stochastic geometry to formulate novel analytical methodologies, explaining some of the most important theoretical boundaries of the achievable enhancements in network performance promised by node cooperation. We start by determining the estimated coverage and rate received by mobile users from convectional cellular networks and from aerial platforms. After that we optimize this coverage and rate ensuring that relay nodes and users can fully exploit their coverage efficiently. We continue by analytically quantifying the cellular network performance during massive infrastructure failure, where some nodes play the role of low-power relays forming multi-hop communication links to assist farther nodes outside the reach of the healthy network coverage. In addition, we lay a mathematical framework for estimating the energy saving of a mediating relay assisting a pair of wireless devices, where we derive closed-form expressions for describing the geometrical zone where relaying is energy efficient. Furthermore, we introduce a novel analytic approach in analyzing the energy consumption of aerial-backhauled wireless nodes on ground fields through the assistance of an aerial base station, the novel mathematical framework is based on Mat\'{e}rn hard-core point process. Then we shed the light on the points interacting of these point processes quantifying their main properties. Throughout this thesis we relay on verifying the analytic results and formulas against computer simulations using Monte-Carlo analysis. We also present practical numerical examples to reflect the usefulness of the presented methodologies and results in real life scenarios. Most of the work presented in this dissertation was published in-part or as a whole in highly ranked peer-reviewed journals, conference proceedings, book chapters, or otherwise currently undergoing a review process. These publications are highlighted and identified in the course of this thesis. Finally, we wish the reader to enjoy exploring the journey of this thesis, and hope it will add more understanding to the promising new technologies of aerial networks and node cooperation
Airports and territory: Emergence of a new strategic actor in the air transport system
This thesis deals with the emergence of the airport as a new strategic actor in the air transport system which has undergone profound changes since its liberalisation and within which the airport turned out to be a major player. Considering the airport as an actor in the air transport system, even if it is affected by its environment in a large sense, this work proposes a contribution to current discussion about airport economics. This contribution refers to two levels: an analysis of the European airport business within which the airport emerges as a full player and an analysis of the link between airport strategy and the spatial and territorial context into which the airport is embedded.
Based on the differentiation of airport strategies according to the airports’ commitment to certain market segments, the analysis of the spatial and territorial context into which the airports are embedded showed its influence on the development of airports but confirmed also that the latter is not automatic but subject to the dynamics arising from the interactions between the different actors. The emergence of the airport as a new strategic player in the air transport system places the emphasis on the complex relation between airport and territory which is reflected in a number of issues connected with the airport activity.Diese Doktorarbeit beschäftigt sich mit dem Flughafen als einem neuen strategischen Akteur im Luftverkehrssystem, welches seit seiner Liberalisierung von weitreichenden Veränderungen erfasst wurde, und in dem der Flughafen sich zum wichtigen Teilnehmer entwickelt hat. Durch die Betrachtung des Flughafens als Akteur des Luftverkehrs, auch wenn er dem Einfluss seiner Umwelt im weitesten Sinne unterliegt, möchte diese Arbeit einen Beitrag zur gegenwärtigen Diskussion zum Thema Flughäfen in zweifacher Hinsicht leisten: Eine Analyse des europäischen Luftverkehrssystems, in dem der Flughafen als ganzheitlicher Partner deutlich wird sowie eine detaillierte Untersuchung der Verbindung zwischen Flughafenstrategien und der Verankerung des Flughafens in Raum und Territorium.
Ausgehend von der Differenzierung der Flughafenstrategien, die durch die Spezialisierung auf ein oder mehrere Marktsegmente ihren Ausdruck findet, lässt die Analyse des räumlichen und territorialen Kontexts, in dem der Flughafen verankert ist, dessen Einfluss auf die Entwicklung des Flughafens deutlich werden, aber bestätigt auch, dass letzere nicht ein automatisches Ergebnis ist, sondern von den Interaktionen der verschiedenen Akteure abhängt. Die Entstehung des Flughafens als neuer strategischer Akteur im Luftverkehrssystem betont die komplexen Beziehungen zwischen Flughafen und Territorium, die sich in einer Reihe von Aspekten widerspiegeln, die in dieser Arbeit diskutiert werden.Cette thèse de doctorat porte sur l’émergence de l’aéroport comme nouvel acteur stratégique dans le système de transport aérien qui a connu de vastes changements depuis sa libéralisation et au sein duquel l’aéroport est devenu un acteur majeur. En considérant l’aéroport comme acteur du transport aérien, bien qu’il soit affecté par son environnement au sens large, ce travail propose une contribution à la discussion récente sur la question des aéroports. Cette contribution se réfère à deux niveaux : une analyse du système de transport aérien européen dans lequel l’aéroport émerge comme partenaire à part entière et une analyse détaillée du lien entre stratégies aéroportuaires et l’ancrage de l’aéroport dans l’espace et dans le territoire.
En partant de la différentiation des stratégies aéroportuaires avec des aéroports qui se spécialisent dans un certain ou plusieurs segments de marché, l’analyse du contexte spatial et territorial, dans lequel les aéroports sont ancrés, a révélé son influence sur le développement des aéroports mais a confirmé aussi que ce dernier n’est pas un résultat mécanique mais est soumis aux dynamiques résultant du jeu d’acteurs. L’émergence de l’aéroport comme nouvel acteur stratégique dans le système de transport aérien met en lumière les rapports complexes entre aéroports et territoire qui se reflètent dans un certain nombre d’aspects discutés dans ce travail
Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року
Second International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2021). Kryvyi Rih, Ukraine, May 19-21, 2021.Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року
Semantic discovery and reuse of business process patterns
Patterns currently play an important role in modern information systems (IS) development and their use has mainly been restricted to the design and implementation phases of the development lifecycle. Given the increasing significance of business modelling in IS development, patterns have the potential of providing a viable solution for promoting reusability of recurrent generalized models in the very early stages of development. As a statement of research-in-progress this paper focuses on business process patterns and proposes an initial methodological framework for the discovery and reuse of business process patterns within the IS development lifecycle. The framework borrows ideas from the domain engineering literature and proposes the use of semantics to drive both the discovery of patterns as well as their reuse
Popular Protest, Political Opportunities, and Change in Africa
This book offers a fresh analysis of third wave popular protests in Africa, shedding light on the complex dynamics between political change and continuity in contemporary Africa.
The book argues that protests are simultaneously products and generators of change in that they are triggered by micro-and-macrosocial changes, but they also have the capacity to transform the nature of politics. By examining the triggers, actors, political opportunities, resources, and framing strategies, the contributors shed light onto tangible (e.g. policy implementation, liberal reforms,
political alternation) and intangible (e.g. perceptions, imagination, awareness)
forms of change elicited by protests. It reveals the relevant role of African protests as engines of democracy, accountability, and collective knowledge.
Bringing popular protests in authoritarian and democratic settings into discussion, this book will be of interest to scholars of African politics, democracy, and protest movements.info:eu-repo/semantics/publishedVersio
Popular Protest, Political Opportunities, and Change in Africa
This book offers a fresh analysis of third wave popular protests in Africa, shedding light on the complex dynamics between political change and continuity in contemporary Africa. The book argues that protests are simultaneously products and generators of change in that they are triggered by micro-and-macrosocial changes, but they also have the capacity to transform the nature of politics. By examining the triggers, actors, political opportunities, resources and framing strategies, the contributors shed light onto tangible (e.g. policy implementation, liberal reforms, political alternation) and intangible (e.g. perceptions, imagination, awareness) forms of change elicited by protests. It reveals the relevant role of African protests as engines of democracy, accountability and collective knowledge. Bringing popular protests in authoritarian and democratic settings into discussion, this book will be of interest to scholars of African politics, democracy and protest movements