Abstract

The goal of this communication is the identification of the model of public television programming with quality programming in its broadest sense. Thus, the doctrinal approach as well as the main public institutions’ views on the contents required to meet the needs of a public service programming are defined. The conclussions state whether the correspondence between public television and quality programming can be established.

Abstract

xtabstractPassenger railway transportation plays a crucial role in the mobility in Europe. Since the privatization of the railway sector in the 90s, passenger satisfaction has become an important performance indicator in this sector. A key aspect for passengers is the reliability of transfers between trains. When a train arrives at the station with a delay, passengers might miss their connection if the next train departs on time. These passengers then prefer the connecting train to wait, but this introduces delays for many other passengers. Delay Management is a field in railway operations that deals with this situation. It determines whether a connecting train should wait for the passengers that arrive with a delayed train or should depart on time. In this thesis, we apply techniques from Operations Research to develop models and solution approaches for Delay Management. The objective in our models is the minimization of passenger delay. First, we extend the classical delay management model with passenger rerouting. This allows us to compute the exact delays for passengers. We develop an exact algorithm and several heuristics to solve this extension. Then, we incorporate the limited capacity of the stations in our models. Stations are the bottlenecks of the railway infrastructure, where delays of one train can easily propagate to other trains. When optimizing the wait-depart decisions, these secondary delays should be considered. We therefore develop an integrated model that includes headway constraints for trains on the same track in the station and an iterative approach that evaluates the timetable microscopically.

Abstract

Today, many small aerodromes have a hard time surviving economically, and amongst the largest cost is air traffic control. Airlines are cutting costs where they can, and many times this affects the aerodromes as well, e.g. when airlines decide to park remotely instead of at the gate. The project called Remotely Operated Towers, initiated by SESAR and run by Saab and LFV, is aiming to address this problem. The project revolves around remotely providing ATS to aerodromes where it is deemed suitable. A big challenge in this project is how to assign aerodromes to remote tower modules in the remote control centre. There are many ways to do this, but there is only a few ways to do it to achieve the least amount of modules. This thesis aims to find an optimal solution to the challenge mentioned above. The thesis resulted in a model where the user can provide the input of choice, i.e. aerodromes with associated ATS operating hours and movements, for a specific period – and receive the assignment schedule for the modules, saying exactly which aerodrome are to be controlled by which module at what time.

Abstract

network-wide coordination system for heavy-duty vehicle platooning with the purpose of reducing fuel consumption is developed. Road freight is by far the dominating mode for overland transport with over 60 % modal share in the OECD countries and is thus critically important for the economy. Overcoming its strong dependency on fossil fuels and manual labor as well as handling rising congestion levels are therefore important societal challenges. Heavy-duty vehicle platooning is a promising near-term automated-driving technology. It combines vehicle-to-vehicle communication and on-board automation to slipstream in a safe manner, which can reduce fuel consumption by more than 10 %. However, in order to realize these benefits in practice, a strategy is needed to form platoons in an operational context. We propose a platoon coordination system that supports the process of automatically forming platoons over large geographic areas. We develop an architecture in which fleet management systems send start locations, destinations, and arrival deadlines to a platoon coordinator. By computing desirable speed profiles and by letting the vehicles' on-board systems track them, vehicles can meet en route and form platoons. Matching vehicles into platoons and deriving suitable speed profiles is treated as an optimization problem with the objective of maximizing the overall fuel savings under the constraint that vehicles arrive in time at their destinations. By updating the speed profiles and the platoon configurations based on real-time measurements of vehicle position and platoon state, the system can accommodate new vehicles joining on the fly. Using real-time measurements also makes the system resilient to disturbances and changing operating conditions. This thesis seeks to develop the theoretical foundations of such a system and evaluate its potential to improve transport efficiency.   We first explore the coordination of vehicle pairs. Fuel-optimal speed profiles are derived. The uncertainty arising from traffic is taken into account by modeling travel time distributions and considering the probability of two vehicles successfully merging. Building on this coordination algorithm for vehicle pairs, we derive algorithms for larger platoons and vehicle fleets. This results in an NP-hard combinatorial optimization problem. The problem is formulated as an integer program and results on the solution structure are derived. In order to handle realistic fleet sizes with thousands of vehicles and continental sized geographical areas under real-time operation, heuristic algorithms are developed. The speed profiles resulting from the combinatorial optimization are further improved using convex optimization. Moreover, we derive efficient algorithms to identify all pairs of vehicles that can platoon. Simulations demonstrate that the proposed algorithm is able to compute plans for thousands of vehicles. Coordinating approximately a tenth of Germany's heavy-duty vehicle traffic, platooning rates over 65 % can be achieved and fuel consumption can be reduced by over 5 %. The proposed system was implemented in a demonstrator system. This demonstrator system has been used in experiments on public roads that show the technical feasibility of en route platoon coordination. Ett nätverksomfattande system för att koordinera körning i lastbilskolonner i syfte att minska bränsleförbrukningen utvecklas i denna avhandling.Vägtransport är med marginal det mest dominerande sättet för landtransport med en andel över 60 % i OECD-länderna och är således avgörande för samhällsekonomin. Dess starka beroende av fossila bränslen och arbetskraft samt ökande trängsel är därför viktiga utmaningar för samhället. Vägtransport är på väg att genomgå grundläggande förändringar genom elektrifiering, kommunikation och automation. Lastbilskolonnkörning är en teknologi för att automatisera fordon, som är redo att lanseras inom en snar framtid. Kolonnkörning kan ge bränslebesparingar på över 10 % tack vare att automatisering och kommunikation mellan fordon möjliggör så kallad slipstreaming på ett säkert sätt. Det behövs dock en strategi för att sätta ihop lastbilskolonner för att kunna dra nytta av denna teknologi. Vi föreslår därför ett automatiserat koordineringssystem som stödjer processen att sätta ihop lastbilskolonner inom stora geografiska områden. Vi utvecklar en arkitektur där fleet management system skickar start- och målpunkter samt senaste ankomsttid till koordineringssystemet. Genom att beräkna passande hastighetsprofiler och genom att låta lastbilarnas färddatorer följa dem kan lastbilar mötas på vägen och bygga ihop kolonner. Problemet att matcha fordon till kolonner och att komma fram till passande hastighetsprofiler hanteras som ett optimeringsproblem med målet att maximera den totala bränslebesparingen. Genom att uppdatera lösningen baserade på realtidsmätningar av fordonspositioner och kolonntillstånd kan systemet hantera tillkommande lastbilar och kan vara robust gentemot störningar och förändrade operativa förutsättningar. Denna avhandling strävar efter att utveckla teoretiska förutsättningar för ett sådant system och att utvärdera dess potential att öka transportsystemets effektivitet. Vi börjar med att undersöka koordinering av fordonspar och härleder bränsleoptimala hastighetsprofiler. Den osäkerhet som beror på trafiken tas hänsyn till genom att modellera hastighetsfördelningar och genom att betrakta sannolikheten att två fordon träffas och kan påbörja kolonnkörning. Vi bygger på denna algoritm för fordonspar för att härleda algoritmer som kan hantera större kolonner och större antal lastbilar. Det resulterar i ett NP-svårt kombinatoriskt optimeringsproblem. Problemet formuleras som ett heltalsoptimieringsproblem och vi kommer fram till resultat som visar strukturen av lösningen. Resulterande hastighetsprofiler förbättras ytterligare med hjälp av konvex optimering. Förutom detta utvecklas effektiva algoritmer för att identifiera alla fordonspar som kan köra i kolonn. Simuleringar demonstrerar att den föreslagna algoritmen klarar att beräkna planer för tusentals lastbilar. Vi visar att en samording av c:a 10 % av Tysklands lastbilstrafik kan tillåta att mer än 65 % av den totala körsträckan körs i kolonn och att bränsleåtgången kan minskas med mer än 5 %. Det presenterade systemet implementerades i ett demonstratorsystem. Experiment med demonstratorn på allmän väg har visat att koordinering av kolonnkörning på vägen är tekniskt genomförbart. "p"QC 20180403

Abstract

xtabstract__Abstract__ Crew management in passenger rail transport is an important factor that contributes to both the quality of service to the railway passengers and to the operational costs of the train operating company. This thesis describes how the (railway) Crew Management process can be improved with the introduction of advanced decision support systems, based on advanced mathematical models and algorithms. We provide a managerial perspective on the change process, related to the introduction of these systems, and give an overview of the lessons learned. We have shown that introducing decision support can give substantial improvements in the overall performance of a railway company. Within NS, the support for the Crew Management process has led to a stable relationship between management and train crew. In addition, the lead-time of the planning process is shortened from months to hours and NS is now able to perform scenario analyses, e.g., to study effects of adjusting the labour rules. Also, NS can adjust their service when severe weather conditions are expected, by creating a specific winter timetable shortly before the day of operation. Finally, we also introduced a decision support system for real-time rescheduling of crew duties on the day of operations. This enables us to adapt the actual crew schedules very quickly. As a result, we reduce the number of cancelled trains and fewer trains will be delayed in case of unforeseen disruptions.

Abstract

Zimbabwe has one of the highest maternal death rates in the world, partly because of the difficulty in getting expectant mothers from rural villages to health care facilities. Specifically designed electric vehicles, called African Solar Taxis, are currently being developed for a rural hospital in Zimbabwe. The vehicles will be charged at solar charging stations located at the hospital and at heath clinics. The vehicles have limited speed and range, and charging is slow compared to conventional vehicles; because of this, efficient scheduling is important. In this article we describe a method for scheduling multiple taxis that share a common charging station. References African Solar Taxis, September 2016. http://africansolartaxi.com . A. Albrecht and P. Pudney. Pick up and delivery with a solar-recharged vehicle. In 22nd National Conference of the Australian Operations Research Society (ASOR 2013), pages 239–246. Australian Society for Operations Research, Dec. 2013. http://www.asor.org.au/conferences/asor2013/J8/albrecht.pdf . K. Marriott and P. J. Stuckey. A MiniZinc tutorial. Technical report, 2015. http://www.minizinc.org/downloads/doc-latest/minizinc-tute.pdf . N. M. Moghaddam. The partially rechargeable electric vehicle routing problem with time windows and capacitated charging stations. PhD thesis, Clemson University, 2015. http://tigerprints.clemson.edu/cgi/viewcontent.cgi?article=3210&context=all_theses . H. Wang and R. Cheu. Operations of a taxi fleet for advance reservations using electric vehicles and charging stations. Trans. Res. Rec.: J. Trans. Res. Board, 2352:1–10, 2013. doi:10.3141/2352-01 . H. P. Williams. Model Building in Mathematical Programming. Wiley, 4th edition, 1999. http://au.wiley.com/WileyCDA/WileyTitle/productCd-1118443330.html .

Abstract

Proceedings of the 48th IEEE Conference on Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. The accurate estimation of airport capacity is critical for the efficient planning of landing and takeoff operations, and the mitigation of congestion-induced delays. The analysis of tradeoffs between arrival and departure capacity at an airport, represented by the airport capacity envelope, has been the main focus of prior research. The increasing demand for air traffic operations has resulted in the growth of multi-airport systems, in which several major airports that are in close proximity of each other serve the same geographical region. The arrival and departure flows into these airports interact with each other, and it is necessary to consider inter-airport arrival-departure capacity tradeoffs while scheduling operations. This paper proposes a statistical technique based on quantile regression, for systematically analyzing arrival-departure capacity tradeoffs in multi-airport systems using observations of flight operations. The proposed technique enables the identification of key factors (such as, runway configuration geometry, weather conditions, etc.) that influence both the capacity envelopes of individual airports, and the capacity envelope of the multi-airport system as a whole. The approach is demonstrated through an analysis of the capacity envelopes of the New York area multi-airport system (comprising Newark (EWR), John F. Kennedy (JFK) and LaGuardia (LGA) airports). Document type: Conference object

Abstract

"jats:p" This is a preface of the translation of the 1967 paper by Linis and Maksim, “On the problem of constructing routes” (in Russian) (in the Proceedings of the Institute of Civil Aviation Engineering, Issue 102, pp. 36-45). It marks 50-year to the deficit function (DF) model initially developed in this 1967 work; the DF model then paved the way to further research of vehicle-fleet management in terms of optimal routing and scheduling. The merit of this translation is to describe the roots of the DF modelling to enable further studies to emerge with more contributions. Document type: Article