Examinando por Autor "Billhardt, Holger"

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A Proposal for Situation-Aware Evacuation Guidance Based on Semantic Technologies
(Springer, Cham, 2017-06-23) Billhardt, Holger; Dunkel, Juergen; Fernández, Alberto; Lujak, Marin; Hermoso, Ramón; Ossowski, Sascha
Smart Cities require reliable means for managing installations that offer essential services to the citizens. In this paper we focus on the problem of evacuation of smart buildings in case of emergencies. In particular, we present a proposal for an evacuation guidance system that provides individualized evacuation support to people in case of emergencies. The system uses sensor technologies and Complex Event Processing to obtain information about the current situation of a building in each moment. Using semantic Web technologies, this information is merged with static knowledge (special user characteristics, building topology, evacuation knowledge) in order to determine (and dynamically update) the most appropriate individualized evacuation routes for each user.
Agreement Technologies for Coordination in Smart Cities
(MDPI, 2018-05-18) Billhardt, Holger; Fernández, Alberto; Lujak, Marin; Ossowski, Sascha
Many challenges in today’s society can be tackled by distributed open systems. This is particularly true for domains that are commonly perceived under the umbrella of smart cities, such as intelligent transportation, smart energy grids, or participative governance. When designing computer applications for these domains, it is necessary to account for the fact that the elements of such systems, often called software agents, are usually made by different designers and act on behalf of particular stakeholders. Furthermore, it is unknown at design time when such agents will enter or leave the system, and what interests new agents will represent. To instil coordination in such systems is particularly demanding, as usually only part of them can be directly controlled at runtime. Agreement technologies refer to a sandbox of tools and mechanisms for the development of such open multiagent systems, which are based on the notion of agreement. In this paper, we argue that agreement technologies are a suitable means for achieving coordination in smart city domains, and back our claim through examples of several real-world applications.
An Ontology for Value Awareness Engineering
(SciTePress, 2024) Holgado-Sánchez, Andrés; Billhardt, Holger; Ossowski, Sascha; Fernández, Alberto
The field of value awareness engineering claims that intelligent software agents should be endowed with a set of capabilities related to human values, enabling them to identify value-aligned outcomes and, ultimately, to choose their behaviour in value-aware manner. In this work we develop an ontology that links many of the models and concepts that have been proposed in relation to computational value awareness, so as to be able to formalize in a common language the various heterogeneous research proposals in the field. Specifically, we illustrate its capability for describing multi-agent systems from the value-awareness engineering perspective through several case studies grounded in concrete approaches from literature. The ontology, implemented in OWL and extended with SWRL rules, is evaluated following scenarios of the NeOn Methodology and is interconnected with relevant ontologies in the Semantic Web.
Bike3S: A tool for bike sharing systems simulation
(Taylor & Francis, 2020-01-30) Fernández, Alberto; Billhardt, Holger; Ossowski, Sascha; Sánchez, Óscar
Vehicle sharing systems are becoming increasingly popular. The effectiveness of such systems depends, among other factors, on different strategic and operational management decisions and policies, like the dimension of the fleet or the distribution of vehicles. It is of foremost importance to be able to anticipate and evaluate the potential effects of such strategies before they can be successfully deployed. In this paper we present Bike3S, a simulator for a station-based bike sharing system. The simulator performs semi-realistic simulations of the operation of a bike sharing system and allows for evaluating and testing different management decisions and strategies. In particular, the simulator has been designed to test different station capacities, station distributions, and balancing strategies. The simulator carries out microscopic agent-based simulations, where users of different types can be defined that act according to their individual goals and objectives which influences the overall dynamics of the whole system.
Dynamic Coordination in Fleet Management Systems: Toward Smart Cyber Fleets
(IEEE Intelligent Systems, 2014) Billhardt, Holger; Fernández, Alberto; Lemus, Lissette; Lujak, Marin; Osman, Nardine; Ossowski, Sascha; Sierra, Carles
Fleet Management Systems are commonly used to coordinate mobility and delivery services in a broad variety of domains. However, their traditional top-down control architecture becomes a bottleneck in open and dynamic environments, where scalability, proactiveness, and autonomy are becoming key factors for their success. In this paper, we first present an abstract event-based architecture for Fleet Management Systems that supports tailoring dynamic control regimes for coordinating fleet vehicles, and illustrate it for the case of medical emergency management. Then, we go one step ahead in the transition towards automatic or driverless fleets, by conceiving Fleet Management Systems in terms of Cyber-Physical Systems, and putting forward the notion of Cyber Fleets. We illustrate the idea in the field of electro mobility, where we expect drivers of smart e-motorbikes (Cyber Vehicles), equipped with an intelligent communication device (Cyber Helmet), to coordinate in a context-aware manner as part of a decentralised Fleet Management System.
Dynamic Coordination of Ambulances for Emergency Medical Assistance Services
(Elsevier, 2014) Billhardt, Holger; Lujak, Marin; Sánchez-Brunete, Vicente; Fernández, Alberto; Ossowski, Sascha
The main objective of emergency medical assistance (EMA) services is to attend patients with sudden dis- eases at any possible location within an area of influence. This usually consists in providing ``in situ¿¿ assistance and, if necessary, the transport of the patient to a medical center. The potential of such systems to reduce mortality is directly related to the travel times of ambulances to emergency patients. An effi- cient coordination of the ambulance fleet of an EMA service is crucial for reducing the average travel times. In this paper we propose mechanisms that dynamically improve the allocation of ambulances to patients as well as the redeployment of available ambulances in the region under consideration. We test these mechanisms in different experiments using historical data from the EMA service of the Auton- omous Region of Madrid in Spain: SUMMA112. The results empirically confirm that our proposal reduces the average response times of EMA services significantly.
Dynamic, fair, and efficient routing for cooperative autonomous vehicle fleets
(Elsevier, 2024-10-01) López Sánchez, Aitor; Lujak, Marin; Semet, Frédérik; Billhardt, Holger
This paper addresses challenges in agricultural cooperative autonomous fleet routing through the proposition, modeling, and resolution of the Dynamic Vehicle Routing Problem with Fair Profits and Time Windows (DVRP-FPTW). The aim is to dynamically optimize routes for a vehicle fleet serving tasks within assigned time windows, emphasizing fair and efficient solutions. Our DVRP-FPTW accommodates unforeseen events like task modifications or vehicle breakdowns, ensuring adherence to task demand, vehicle capacities, and autonomies. The proposed model incorporates mandatory and optional tasks, including optional ones in operational vehicle routes if not compromising the vehicles’ profits. Including asynchronous and distributed column generation heuristics, the proposed Multi-Agent-based architecture DIMASA for the DVRP-FPTW dynamically adapts to unforeseen events. Systematic Egalitarian social welfare optimization is used to iteratively maximize the profit of the least profitable vehicle, prioritizing fairness across the fleet in light of unforeseen events. This improves upon existing dynamic and multi-period VRP models that rely on prior knowledge of demand changes. Our approach allows vehicle agents to maintain privacy while sharing minimal local data with a fleet coordinator agent. We propose publicly available benchmark instances for both static and dynamic VRP-FPTW. Simulation results demonstrate the effectiveness of our DVRP-FPTW model and our multi-agent system solution approach in coordinating large, dynamically evolving cooperative autonomous fleets fairly and efficiently in close to real-time
Inteligencia Artificial: Ejercicios
(2023) Billhardt, Holger; Fernández Gil, Alberto; Ossowski, Sascha
Inteligencia Artificial: Exámenes
(2023) Billhardt, Holger; Fernández Gil, Alberto; Ossowski, Sascha
Inteligencia Artificial: Guías docentes
(2023) Billhardt, Holger; Fernández Gil, Alberto; Ossowski, Sascha
Inteligencia Artificial: Transparencias
(2023) Billhardt, Holger; Fernández Gil, Alberto; Ossowski, Sascha
Legal and ethical implications of applications based on agreement technologies: the case of auction‐based road intersections
(Springer, 2020) Santos, José‐Antonio; Fernández, Alberto; Moreno‐Rebato, Mar; Billhardt, Holger; Rodríguez‐García, José‐A.; Ossowski, Sascha
Agreement technologies refer to a novel paradigm for the construction of distributed intelligent systems, where autonomous software agents negotiate to reach agreements on behalf of their human users. Smart Cities are a key application domain for agreement technologies. While several proofs of concept and prototypes exist, such systems are still far from ready for being deployed in the real-world. In this paper we focus on a novel method for managing elements of smart road infrastructures of the future, namely the case of auction-based road intersections. We show that, even though the key technological elements for such methods are already available, there are multiple non-technical issues that need to be tackled before they can be applied in practice. For this purpose, we analyse legal and ethical implications of auction-based road intersections in the context of international regulations and from the standpoint of the Spanish legislation. From this exercise, we extract a set of required modifications, of both technical and legal nature, which need to be addressed so as to pave the way for the potential real-world deployment of such systems in a future that may not be too far away.
Organisational Structures in Next-Generation Distributed Systems: Towards a Technology of Agreement
(IOS Press, 2011) Billhardt, Holger; Centeno, Roberto; Carlos E. Cuesta; Fernández, Alberto; Hermoso, Ramón; Ortiz, Rubén; Ossowski, Sascha; Pérez, José Santiago; Vasirani, Matteo
This article provides a brief overview of the field of coordination in multiagent systems, and outlines its relation to current efforts working towards a paradigm for smart, next-generation distributed systems, where coordination is based on the concept of agreement between computational entities. Two examples are provided to visualize the types of mechanisms that can be part of a ¿technology of agreement¿. They explain how techniques from the field of organisations can be used to further coordination and agreement in open multiagent systems. This approach requires autonomy of the coordinated systems and their constituting agents, implying also the need for eventual reorganization and self-adaptation ¿ hence the article presents also an architectural strategy to tackle the inherent dynamism in these features.
Problem Detection in the Edge of IoT Applications
(UNIR, 2023-07-26) Bernabé-Sánchez, Iván; Fernández, Alberto; Billhardt, Holger; Ossowski, Sascha
Due to technological advances, Internet of Things (IoT) systems are becoming increasingly complex. They are characterized by being multi-device and geographically distributed, which increases the possibility of errors of different types. In such systems, errors can occur anywhere at any time and fault tolerance becomes an essential characteristic to make them robust and reliable. This paper presents a framework to manage and detect errors and malfunctions of the devices that compose an IoT system. The proposed solution approach takes into account both, simple devices such as sensors or actuators, as well as computationally intensive devices which are distributed geographically. It uses knowledge graphs to model the devices, the system's topology, the software deployed on each device and the relationships between the different elements. The proposed framework retrieves information from log messages and processes this information automatically to detect anomalous situations or malfunctions that may affect the IoT system. This work also presents the ECO ontology to organize the IoT system information.
Smart Recommendations for Renting Bikes in Bike-Sharing Systems
(MDPI, 2021-10-16) Billhardt, Holger; Fernández, Alberto; Ossowski, Sascha
Vehicle-sharing systems—such as bike-, car-, or motorcycle-sharing systems—have become increasingly popular in big cities in recent years. On the one hand, they provide a cheaper and environmentally friendlier means of transportation than private cars, and on the other hand, they satisfy the individual mobility demands of citizens better than traditional public transport systems. One of their advantages in this regard is their availability, e.g., the possibility of taking (or leaving) a vehicle almost anywhere in a city. This availability obviously depends on different strategic and operational management decisions and policies, such as the dimension of the fleet or the (re)distribution of vehicles. Agglutination problems—where, due to usage patterns, available vehicles are concentrated in certain areas, whereas no vehicles are available in others—are quite common in such systems, and need to be dealt with. Research has been dedicated to this problem, specifying different techniques to reduce imbalanced situations. In this paper, we present and compare strategies for recommending stations to users who wish to rent or return bikes in station-based bike-sharing systems. Our first contribution is a novel recommendation strategy based on queuing theory that recommends stations based on their utility to the user in terms of lower distance and higher probability of finding a bike or slot. Then, we go one step further, defining a strategy that recommends stations by combining the utility of a particular user with the utility of the global system, measured in terms of the improvement in the distribution of bikes and slots with respect to the expected future demand, with the aim of implicitly avoiding or alleviating balancing problems. We present several experiments to evaluate our proposal with real data from the bike sharing system BiciMAD in Madrid.
Streamlining advanced taxi assignment strategies based on legal analysis
(Elsevier, 2021) Billhardt, Holger; Santos, José-Antonio; Fernández, Alberto; Moreno, Mar; Ossowski, Sascha; Rodríguez, José A.
In recent years many novel applications have appeared that promote the provision of services and activities in a collaborative manner. The key idea behind such systems is to take advantage of idle or underused capacities of existing resources, in order to provide improved services that assist people in their daily tasks, with additional functionality, enhanced efficiency, and/or reduced cost. Particularly in the domain of urban transportation, many researchers have put forward novel ideas, which are then implemented and evaluated through prototypes that usually draw upon AI methods and tools. However, such proposals also bring up multiple non-technical issues that need to be identified and addressed adequately if such systems are ever meant to be applied to the real world. While, in practice, legal and ethical aspects related to such AI-based systems are seldomly considered in the beginning of the research and development process, we argue that they not only restrict design decisions, but can also help guiding them. In this manuscript, we set out from a prototype of a taxi coordination service that mediates between individual (and autonomous) taxis and potential customers. After representing key aspects of its operation in a semi-structured manner, we analyse its viability from the viewpoint of current legal restrictions and constraints, so as to identify additional non-functional requirements as well as options to address them. Then, we go one step ahead, and actually modify the existing prototype to incorporate the previously identified recommendations. Performing experiments with this improved system helps us identify the most adequate option among several legally admissible alternatives.
Taxi dispatching strategies with compensations
(Elsevier, 2019-01-03) Billhardt, Holger; Fernández, Alberto; Ossowski, Sascha; Palanca, Javier; Bajo, Javier
Urban mobility efficiency is of utmost importance in big cities. Taxi vehicles are key elements in daily traffic activity. The advance of ICT and geo-positioning systems has given rise to new opportunities for improving the efficiency of taxi fleets in terms of waiting times of passengers, cost and time for drivers, traffic density, CO2 emissions, etc., by using more informed, intelligent dispatching. Still, the explicit spatial and temporal components, as well as the scale and, in particular, the dynamicity of the problem of pairing passengers and taxis in big towns, render traditional approaches for solving standard assignment problem useless for this purpose, and call for intelligent approximation strategies based on domain-specific heuristics. Furthermore, taxi drivers are often autonomous actors and may not agree to participate in assignments that, though globally efficient, may not be sufficently beneficial for them individually. This paper presents a new heuristic algorithm for taxi assignment to customers that considers taxi reassignments if this may lead to globally better solutions. In addition, as such new assignments may reduce the expected revenues of individual drivers, we propose an economic compensation scheme to make individually rational drivers agree to proposed modifications in their assigned clients. We carried out a set of experiments, where several commonly used assignment strategies are compared to three different instantiations of our heuristic algorithm. The results indicate that our proposal has the potential to reduce customer waiting times in fleets of autonomous taxis, while being also beneficial from an economic point of view.
Towards the Prioritised Use of Transportation Infrastructures: The Case of Vehicle-Specific Dynamic Access Restrictions in City Centres
(MDPI, 2022-02-14) Billhardt, Holger; Fernández, Alberto; Martí, Pasqual; Prieto Tejedor, Javier; Ossowski, Sascha
One of the main problems that local authorities of large cities have to face is the regulation of urban mobility. They need to provide the means to allow for the efficient movement of people and distribution of goods. However, the provisioning of transportation services needs to take into account general global objectives, like reducing emissions and having more healthy living environments, which may not always be aligned with individual interests. Urban mobility is usually provided through a transport infrastructure that includes all the elements that support mobility. On many occasions, the capacity of the elements of this infrastructure is lower than the actual demand and thus different transportation activities compete for their use. In this paper, we argue that scarce transport infrastructure elements should be assigned dynamically and in a prioritised manner to transport activities that have a higher utility from the point of view of society; for example, activities that produce less pollution and provide more value to society. In this paper, we define a general model for prioritizing the use of a particular type of transportation infrastructure element called time-unlimited elements, whose usage time is unknown a priori, and illustrate its dynamics through two use cases: vehicle-specific dynamic access restriction in city centres (i) based on the usage levels of available parking spaces and (ii) to assure sustained admissible air quality levels in the city centre. We carry out several experiments using the SUMO traffic simulation tool to evaluate our proposal.