Michel Ferreira - Profile on Academia.edu (original) (raw)
Papers by Michel Ferreira
WAM Local Analysis
Lecture Notes in Computer Science, 2002
The abstract interpretation framework has been used mainly in the global analysis of programs. Mo... more The abstract interpretation framework has been used mainly in the global analysis of programs. Most often also, this interpretation is applied to the source Prolog program. In this paper we present an abstract interpretation of more local nature, and applied to the intermediate code (WAM). The purpose of obtaining a more efficient specialized version of the program remains the same
The MyYapDB Deductive Database System
Lecture Notes in Computer Science, 2004
We describe the MyYapDB, a deductive database system coupling the Yap Prolog compiler and the MyS... more We describe the MyYapDB, a deductive database system coupling the Yap Prolog compiler and the MySQL DBMS. We use our OPTYap extension of the Yap compiler, which is the first available system that can exploit parallelism from tabled logic programs. We describe the major features of the system, give a simplified description of the implementation and present a performance comparison
Large-scale simulation of V2V environments
Proceedings of the 2008 ACM symposium on Applied computing - SAC '08, 2008
Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira ... more Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira DCC/FCUP & LIACC University of Porto R. Campo Alegre, 1021/1055 4169-007 Porto, Portugal {hc,luis,michel}@dcc.fc.up.pt ...
Using exit time predictions to optimize self automated parking lots
17th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2014
Lecture Notes in Computer Science, 2012
In recent years, both companies and researchers have been exploring intelligent data analysis to ... more In recent years, both companies and researchers have been exploring intelligent data analysis to increase the profitability of the taxi industry. Intelligent systems for online taxi dispatching and time saving route finding have been built to do so. In this paper, we propose a novel methodology to produce online predictions regarding the spatial distribution of passenger demand throughout taxi stand networks. We have done so by assembling two well-known time series short-term forecast models: the time-varying Poisson models and ARIMA models. Our tests were performed using data gathered over a period of 6 months and collected from 63 taxi stands within the city of Porto, Portugal. Our results demonstrate that this model is a true major contribution to the driver mobility intelligence: 78% of the 253745 demanded taxi services were correctly forecasted in a 30 minutes horizon.
User Defined Indexing
Lecture Notes in Computer Science, 2009
Abstract. Logic programming provides an ideal framework for tackling complex data, such as the mu... more Abstract. Logic programming provides an ideal framework for tackling complex data, such as the multi-dimensional vector-based data used to represent spatial databases. Unfortunately, the usefulness of logic pro-gramming systems if often hampered by the fact that most of ...
Large-scale simulation of V2V environments
ACM Symposium on Applied Computing, 2008
Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira ... more Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira DCC/FCUP & LIACC University of Porto R. Campo Alegre, 1021/1055 4169-007 Porto, Portugal {hc,luis,michel}@dcc.fc.up.pt ...
Stereoscopic aerial photography: an alternative to model-based urban mobility approaches
Mobile Computing and Networking, 2009
Abstract In the absence of large-scale deployments of VANETs, simulation based research is until ... more Abstract In the absence of large-scale deployments of VANETs, simulation based research is until now the only choice available to address and validate the design of protocols in the context of vehicular networks. The simulation frameworks involved in this research have to ...
Can ride-sharing become attractive? A case study of taxi-sharing employing a simulation modelling approach
IET Intelligent Transport Systems, 2015
ABSTRACT Improved urban mobility can be attained through more efficient vehicle usage and better ... more ABSTRACT Improved urban mobility can be attained through more efficient vehicle usage and better road network utilisation, namely through increased vehicle occupancy and new operation modes. In this study, the authors focus on a dynamic and distributed taxi-sharing system that takes advantage of nowadays widespread availability of communication and distributed computation to provide a cost-efficient, door-to-door and flexible service, offering a quality of service similar to conventional taxis. This system has been evaluated following a simulation modelling approach, including a realistic and accurate replication of the taxi operation in the city of Porto using empirical data (real origin/destination data and average occupancy rates). Simulation results show improved performance in terms of reduced fares (up to 8%), reduced total travel distance (up to 9%) and smaller operation costs. Furthermore, they proposed that several trade-offs (e.g. service performance against passengers' transit times) should be considered during the system deployment and operation. In this study, it was also shown that increased system penetration rate and demand level can even further improve the system performance.
Multiple Specialization of WAM Code
Lecture Notes in Computer Science, 1998
Program specialization is normally supported by global analysis of the program. Compilers use the... more Program specialization is normally supported by global analysis of the program. Compilers use the information deduced to generate more efficient, specialized implementations of the program. This specialization can be single or multiple, depending if each procedure of the program is specialized into one or more versions. We present a Prolog compiler that does multiple specialization, using an algorithm that works
21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2010
Self-optimisation will enable future wireless networks to manage themselves in a continuous and i... more Self-optimisation will enable future wireless networks to manage themselves in a continuous and independent way. By dynamically adjusting relevant radio parameters during network operation a system that adapts to environmental changes can be created. This paper presents a novel selfoptimisation algorithm based on Fuzzy Logic Controlling. Taking into consideration measurements gathered from the network, the Fuzzy Logic Controller balances continuously the individual link gain and the network gain. Results have shown the feasibility of the proposed approach, superior improvements on network performance and a capacity increase of 23%. It is envisioned that self-optimisation will lead to significant reductions in capital and operational expenditures by maximizing the utilisation of the air interface.
2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012
Abstract² In the last decade, the real-time vehicle location systems attracted everyone attention... more Abstract² In the last decade, the real-time vehicle location systems attracted everyone attention for the new kind of rich spatio-temporal information. The fast processing of this large amount of information is a growing and explosive challenge. Taxi companies are already exploring such information in efficient taxi dispatching and time-saving route finding. In this paper, we propose a novel methodology to produce online short term predictions on the passenger demand spatial distribution over 63 taxi stands in the city of Porto, Portugal. We did so using time series forecasting techniques to the processed events constantly communicated for 441 taxi vehicles. Our tests -using 4 months of real data -demonstrated that this model is a true major contribution to the driver mobility intelligence: 76% of the 86411 demanded taxi services were accurately forecasted in a 30 minutes time horizon.
Virtual traffic lights in partial deployment scenarios
2013 IEEE Intelligent Vehicles Symposium (IV), 2013
ABSTRACT Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for impr... more ABSTRACT Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for improving both traffic safety and efficiency. Virtual Traffic Lights (VTLs) are a promising proposal for reducing travel time by efficiently controlling road intersections. VTLs use vehicle-to-vehicle communication to dynamically optimize traffic flow and they display traffic light information on the windshield. However, research so far has assumed that all vehicles are equipped with VTL support and it has ignored the incremental deployment phase, which could last decades. In this paper we present a solution for a VTL partial deployment scenario that is based on the idea of having VTL equipped cars display traffic light information on the outside of the vehicle. This allows drivers in non-equipped vehicles, or even pedestrians, to see the light color and respond accordingly. We show that the benefits of VTLs in terms of intersection throughput and average delay reduction grow as a function of the penetration rate of equipped vehicles.
Lecture Notes in Computer Science, 2008
Aiming at a realistic mobile connectivity model for vehicular sensor networks in urban environmen... more Aiming at a realistic mobile connectivity model for vehicular sensor networks in urban environments, we propose the combination of large-scale traffic simulation and computational tools to characterize fundamental graph-theoretic parameters. To illustrate the proposed approach, we use the DIVERT simulation framework to illuminate the temporal evolution of the average node degree in this class of networks and provide an algorithm for computing the transitive connectivity profile that ultimately determines the flow of information in a vehicular sensor network.
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
Motivated by the recent surge in vehicular ad-hoc network (VANET) research and the promise of hig... more Motivated by the recent surge in vehicular ad-hoc network (VANET) research and the promise of high-impact applications such as safety, navigation and infotainment services, we consider the impact of mobility mis-modeling on the design and development of this class of distributed systems. Focusing on urban environments, we use a state-of-the-art car traffic simulator to extract some of the key connectivity metrics relevant for the design of a vehicle-to-vehicle traffic information system. We compare such metrics against those obtained from popular mobility models, such as the random waypoint model and the Manhattan mobility model. Our results reveal striking differences in the connectivity profile of the network, thus casting some doubt on the adequacy of simple mobility models for the development of future VANET protocols.
2009 IEEE 70th Vehicular Technology Conference Fall, 2009
Connectivity analysis of Vehicular Ad Hoc Networks (VANETs) involves the study of static and dyna... more Connectivity analysis of Vehicular Ad Hoc Networks (VANETs) involves the study of static and dynamic characteristics of the network. Realistic mobility models are essential for both aspects, in order to produce valid configurations of the position of vehicles in one static instant, and to dynamically move such vehicles in an interval of time. Focusing on static connectivity evaluation, we extend the state-of-the-art of the realism of urban mobility models for VANETs, by proposing and implementing an analysis based on a stereoscopic aerial survey over a large European city. Our static connectivity metrics show important differences compared to the model and simulation based results described in the VANET literature.
VNS: An integrated framework for vehicular networks simulation
2012 IEEE Vehicular Networking Conference (VNC), 2012
Abstract Vehicular networks are becoming one of the most important emerging technologies to enabl... more Abstract Vehicular networks are becoming one of the most important emerging technologies to enable Intelligent Transportation Systems (ITS). A strong research effort has been made in the last few years in the design and development of new systems using vehicle-to-vehicle or vehicle-to-infrastructure communications. Therefore, a large-scale evaluation of these networks is of critical importance. However, due to the prohibitive costs of real test-beds, computer simulation is the only viable solution. Building upon previous work, we extend ...
2012 12th International Conference on ITS Telecommunications, 2012
Considering the fast development of urban areas and the increasing environmental awareness, we fo... more Considering the fast development of urban areas and the increasing environmental awareness, we focus in this paper on a taxi-sharing system for improving the efficiency of public transport. In particular, we present a realistic and largescale evaluation of the environmental impact of this system. The proposed method improves the efficiency of this form of public transport by determining, on the fly, the best match between taxi user requests, which leads to a reduction of the total and vacant travel distance. Our results show important reductions of CO2 emissions with full deployment of the system, reaching 9% under a higher demand scenario.
Scalable VANET Simulations with NS-3
2012 IEEE 75th Vehicular Technology Conference (VTC Spring), 2012
Abstract The study of large scale scenarios in vehicular ad-hoc networks is of critical importanc... more Abstract The study of large scale scenarios in vehicular ad-hoc networks is of critical importance to the design of communication protocols and applications. Since management and operation of a large number of real nodes is unpractical, simulation is considered as the most viable methodology to evaluate such large scale scenarios. However, the widely used simulator NS-3 has limited performance and scalability, causing the simulation of medium scale networks with more than 1,000 nodes to become very hard. In this paper we identify ...
Lecture Notes in Computer Science, 2011
Inter-vehicle communication is becoming increasingly relevant in the research and development of ... more Inter-vehicle communication is becoming increasingly relevant in the research and development of novel, innovative vehicular applications. To support the driver in his/her primary driving task in an effective non distracting way, these applications need to be evaluated in a realistic context from a driver's perspective of the VANET environment. In this paper we propose an innovative driver-centric simulation tool that integrates a VANET simulator with a driving simulator using communication technologies to relay information about the vehicle to the VANET environment and vice versa. The driver behavior is reflected in the VANET simulation system affecting the mobility of the cars in the vicinity and providing the intelligent driving model with new realistic features.
WAM Local Analysis
Lecture Notes in Computer Science, 2002
The abstract interpretation framework has been used mainly in the global analysis of programs. Mo... more The abstract interpretation framework has been used mainly in the global analysis of programs. Most often also, this interpretation is applied to the source Prolog program. In this paper we present an abstract interpretation of more local nature, and applied to the intermediate code (WAM). The purpose of obtaining a more efficient specialized version of the program remains the same
The MyYapDB Deductive Database System
Lecture Notes in Computer Science, 2004
We describe the MyYapDB, a deductive database system coupling the Yap Prolog compiler and the MyS... more We describe the MyYapDB, a deductive database system coupling the Yap Prolog compiler and the MySQL DBMS. We use our OPTYap extension of the Yap compiler, which is the first available system that can exploit parallelism from tabled logic programs. We describe the major features of the system, give a simplified description of the implementation and present a performance comparison
Large-scale simulation of V2V environments
Proceedings of the 2008 ACM symposium on Applied computing - SAC '08, 2008
Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira ... more Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira DCC/FCUP & LIACC University of Porto R. Campo Alegre, 1021/1055 4169-007 Porto, Portugal {hc,luis,michel}@dcc.fc.up.pt ...
Using exit time predictions to optimize self automated parking lots
17th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2014
Lecture Notes in Computer Science, 2012
In recent years, both companies and researchers have been exploring intelligent data analysis to ... more In recent years, both companies and researchers have been exploring intelligent data analysis to increase the profitability of the taxi industry. Intelligent systems for online taxi dispatching and time saving route finding have been built to do so. In this paper, we propose a novel methodology to produce online predictions regarding the spatial distribution of passenger demand throughout taxi stand networks. We have done so by assembling two well-known time series short-term forecast models: the time-varying Poisson models and ARIMA models. Our tests were performed using data gathered over a period of 6 months and collected from 63 taxi stands within the city of Porto, Portugal. Our results demonstrate that this model is a true major contribution to the driver mobility intelligence: 78% of the 253745 demanded taxi services were correctly forecasted in a 30 minutes horizon.
User Defined Indexing
Lecture Notes in Computer Science, 2009
Abstract. Logic programming provides an ideal framework for tackling complex data, such as the mu... more Abstract. Logic programming provides an ideal framework for tackling complex data, such as the multi-dimensional vector-based data used to represent spatial databases. Unfortunately, the usefulness of logic pro-gramming systems if often hampered by the fact that most of ...
Large-scale simulation of V2V environments
ACM Symposium on Applied Computing, 2008
Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira ... more Page 1. Large-Scale Simulation of V2V Environments Hugo Conceiç ao, Luıs Damas, Michel Ferreira DCC/FCUP & LIACC University of Porto R. Campo Alegre, 1021/1055 4169-007 Porto, Portugal {hc,luis,michel}@dcc.fc.up.pt ...
Stereoscopic aerial photography: an alternative to model-based urban mobility approaches
Mobile Computing and Networking, 2009
Abstract In the absence of large-scale deployments of VANETs, simulation based research is until ... more Abstract In the absence of large-scale deployments of VANETs, simulation based research is until now the only choice available to address and validate the design of protocols in the context of vehicular networks. The simulation frameworks involved in this research have to ...
Can ride-sharing become attractive? A case study of taxi-sharing employing a simulation modelling approach
IET Intelligent Transport Systems, 2015
ABSTRACT Improved urban mobility can be attained through more efficient vehicle usage and better ... more ABSTRACT Improved urban mobility can be attained through more efficient vehicle usage and better road network utilisation, namely through increased vehicle occupancy and new operation modes. In this study, the authors focus on a dynamic and distributed taxi-sharing system that takes advantage of nowadays widespread availability of communication and distributed computation to provide a cost-efficient, door-to-door and flexible service, offering a quality of service similar to conventional taxis. This system has been evaluated following a simulation modelling approach, including a realistic and accurate replication of the taxi operation in the city of Porto using empirical data (real origin/destination data and average occupancy rates). Simulation results show improved performance in terms of reduced fares (up to 8%), reduced total travel distance (up to 9%) and smaller operation costs. Furthermore, they proposed that several trade-offs (e.g. service performance against passengers' transit times) should be considered during the system deployment and operation. In this study, it was also shown that increased system penetration rate and demand level can even further improve the system performance.
Multiple Specialization of WAM Code
Lecture Notes in Computer Science, 1998
Program specialization is normally supported by global analysis of the program. Compilers use the... more Program specialization is normally supported by global analysis of the program. Compilers use the information deduced to generate more efficient, specialized implementations of the program. This specialization can be single or multiple, depending if each procedure of the program is specialized into one or more versions. We present a Prolog compiler that does multiple specialization, using an algorithm that works
21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2010
Self-optimisation will enable future wireless networks to manage themselves in a continuous and i... more Self-optimisation will enable future wireless networks to manage themselves in a continuous and independent way. By dynamically adjusting relevant radio parameters during network operation a system that adapts to environmental changes can be created. This paper presents a novel selfoptimisation algorithm based on Fuzzy Logic Controlling. Taking into consideration measurements gathered from the network, the Fuzzy Logic Controller balances continuously the individual link gain and the network gain. Results have shown the feasibility of the proposed approach, superior improvements on network performance and a capacity increase of 23%. It is envisioned that self-optimisation will lead to significant reductions in capital and operational expenditures by maximizing the utilisation of the air interface.
2012 15th International IEEE Conference on Intelligent Transportation Systems, 2012
Abstract² In the last decade, the real-time vehicle location systems attracted everyone attention... more Abstract² In the last decade, the real-time vehicle location systems attracted everyone attention for the new kind of rich spatio-temporal information. The fast processing of this large amount of information is a growing and explosive challenge. Taxi companies are already exploring such information in efficient taxi dispatching and time-saving route finding. In this paper, we propose a novel methodology to produce online short term predictions on the passenger demand spatial distribution over 63 taxi stands in the city of Porto, Portugal. We did so using time series forecasting techniques to the processed events constantly communicated for 441 taxi vehicles. Our tests -using 4 months of real data -demonstrated that this model is a true major contribution to the driver mobility intelligence: 76% of the 86411 demanded taxi services were accurately forecasted in a 30 minutes time horizon.
Virtual traffic lights in partial deployment scenarios
2013 IEEE Intelligent Vehicles Symposium (IV), 2013
ABSTRACT Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for impr... more ABSTRACT Vehicular ad hoc networks (VANETs) are seen as an important enabling technology for improving both traffic safety and efficiency. Virtual Traffic Lights (VTLs) are a promising proposal for reducing travel time by efficiently controlling road intersections. VTLs use vehicle-to-vehicle communication to dynamically optimize traffic flow and they display traffic light information on the windshield. However, research so far has assumed that all vehicles are equipped with VTL support and it has ignored the incremental deployment phase, which could last decades. In this paper we present a solution for a VTL partial deployment scenario that is based on the idea of having VTL equipped cars display traffic light information on the outside of the vehicle. This allows drivers in non-equipped vehicles, or even pedestrians, to see the light color and respond accordingly. We show that the benefits of VTLs in terms of intersection throughput and average delay reduction grow as a function of the penetration rate of equipped vehicles.
Lecture Notes in Computer Science, 2008
Aiming at a realistic mobile connectivity model for vehicular sensor networks in urban environmen... more Aiming at a realistic mobile connectivity model for vehicular sensor networks in urban environments, we propose the combination of large-scale traffic simulation and computational tools to characterize fundamental graph-theoretic parameters. To illustrate the proposed approach, we use the DIVERT simulation framework to illuminate the temporal evolution of the average node degree in this class of networks and provide an algorithm for computing the transitive connectivity profile that ultimately determines the flow of information in a vehicular sensor network.
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
Motivated by the recent surge in vehicular ad-hoc network (VANET) research and the promise of hig... more Motivated by the recent surge in vehicular ad-hoc network (VANET) research and the promise of high-impact applications such as safety, navigation and infotainment services, we consider the impact of mobility mis-modeling on the design and development of this class of distributed systems. Focusing on urban environments, we use a state-of-the-art car traffic simulator to extract some of the key connectivity metrics relevant for the design of a vehicle-to-vehicle traffic information system. We compare such metrics against those obtained from popular mobility models, such as the random waypoint model and the Manhattan mobility model. Our results reveal striking differences in the connectivity profile of the network, thus casting some doubt on the adequacy of simple mobility models for the development of future VANET protocols.
2009 IEEE 70th Vehicular Technology Conference Fall, 2009
Connectivity analysis of Vehicular Ad Hoc Networks (VANETs) involves the study of static and dyna... more Connectivity analysis of Vehicular Ad Hoc Networks (VANETs) involves the study of static and dynamic characteristics of the network. Realistic mobility models are essential for both aspects, in order to produce valid configurations of the position of vehicles in one static instant, and to dynamically move such vehicles in an interval of time. Focusing on static connectivity evaluation, we extend the state-of-the-art of the realism of urban mobility models for VANETs, by proposing and implementing an analysis based on a stereoscopic aerial survey over a large European city. Our static connectivity metrics show important differences compared to the model and simulation based results described in the VANET literature.
VNS: An integrated framework for vehicular networks simulation
2012 IEEE Vehicular Networking Conference (VNC), 2012
Abstract Vehicular networks are becoming one of the most important emerging technologies to enabl... more Abstract Vehicular networks are becoming one of the most important emerging technologies to enable Intelligent Transportation Systems (ITS). A strong research effort has been made in the last few years in the design and development of new systems using vehicle-to-vehicle or vehicle-to-infrastructure communications. Therefore, a large-scale evaluation of these networks is of critical importance. However, due to the prohibitive costs of real test-beds, computer simulation is the only viable solution. Building upon previous work, we extend ...
2012 12th International Conference on ITS Telecommunications, 2012
Considering the fast development of urban areas and the increasing environmental awareness, we fo... more Considering the fast development of urban areas and the increasing environmental awareness, we focus in this paper on a taxi-sharing system for improving the efficiency of public transport. In particular, we present a realistic and largescale evaluation of the environmental impact of this system. The proposed method improves the efficiency of this form of public transport by determining, on the fly, the best match between taxi user requests, which leads to a reduction of the total and vacant travel distance. Our results show important reductions of CO2 emissions with full deployment of the system, reaching 9% under a higher demand scenario.
Scalable VANET Simulations with NS-3
2012 IEEE 75th Vehicular Technology Conference (VTC Spring), 2012
Abstract The study of large scale scenarios in vehicular ad-hoc networks is of critical importanc... more Abstract The study of large scale scenarios in vehicular ad-hoc networks is of critical importance to the design of communication protocols and applications. Since management and operation of a large number of real nodes is unpractical, simulation is considered as the most viable methodology to evaluate such large scale scenarios. However, the widely used simulator NS-3 has limited performance and scalability, causing the simulation of medium scale networks with more than 1,000 nodes to become very hard. In this paper we identify ...
Lecture Notes in Computer Science, 2011
Inter-vehicle communication is becoming increasingly relevant in the research and development of ... more Inter-vehicle communication is becoming increasingly relevant in the research and development of novel, innovative vehicular applications. To support the driver in his/her primary driving task in an effective non distracting way, these applications need to be evaluated in a realistic context from a driver's perspective of the VANET environment. In this paper we propose an innovative driver-centric simulation tool that integrates a VANET simulator with a driving simulator using communication technologies to relay information about the vehicle to the VANET environment and vice versa. The driver behavior is reflected in the VANET simulation system affecting the mobility of the cars in the vicinity and providing the intelligent driving model with new realistic features.