Public road authorities and private mobility service providers need information derived from the ... more Public road authorities and private mobility service providers need information derived from the current and predicted traffic states to act upon the daily urban system and its spatial and temporal dynamics. In this research, a real-time parking area state (occupancy, in- and outflux) prediction model (up to 60 minutes ahead) has been developed using publicly available historic and real time data sources. Based on a case study in a real-life scenario in the city of Arnhem, a Neural Network-based approach outperforms a Random Forest-based one on all assessed performance measures, although the differences are small. Both are outperforming a naive seasonal random walk model. Although the performance degrades with increasing prediction horizon, the model shows a performance gain of over 150% at a prediction horizon of 60 minutes compared with the naive model. Furthermore, it is shown that predicting the in- and outflux is a far more difficult task (i.e. performance gains of 30%) which n...
Abstract In this technical report we propose algorithms for implementing the axes for element nod... more Abstract In this technical report we propose algorithms for implementing the axes for element nodes in XPath given a DOM-like representation of the document. First, we construct algorithms for evaluating simple step expressions, withoout any (positional) predicates. The time complexity of these algorithms is at most O (l+ m) where l is the size of the input list and m the size of the output list.
Abstract In this document the design of a system capable of scouting and mapping an environment u... more Abstract In this document the design of a system capable of scouting and mapping an environment using a LEGO robot is described. This is achieved by building a LEGO robot that can drive around freely and take spatial measurements of the environment using a distance sensor mounted on top of it in a radar-like setup. The robot has problems achieving the required movement precision for the demanded map detail.
Abstract The usage of social networks sites (SNSs), such as Facebook, and geosocial networks (GSN... more Abstract The usage of social networks sites (SNSs), such as Facebook, and geosocial networks (GSNs), such as Foursquare, has increased tremendously over the past years. The willingness of users to share their current locations and experiences facilitate the creation of geographical recommender systems based on user generated content (UGC).
Welcome to the second Twente Data Management Workshop. The topic of this second edition is Uncert... more Welcome to the second Twente Data Management Workshop. The topic of this second edition is Uncertainty in Databases. This topic has gained more and more attention these last years. This is clearly visible by the increasing number of workshops on, or related to this topic.
1. INTRODUCTION Accessing information is an essential factor in decision making processes occurri... more 1. INTRODUCTION Accessing information is an essential factor in decision making processes occurring in different domains. Therefore, broadening the coverage of available information for the decision makers is of a vital importance. In such a informationthirsty environment, accessing every source of information is considered highly valuable. Nowadays, the main or the most general approach for finding and accessing information sources is searching queries over general search engines such as Google, Yahoo, or Bing.
Abstract Information Extraction, data Integration, and uncertain data management are different ar... more Abstract Information Extraction, data Integration, and uncertain data management are different areas of research that got vast focus in the last two decades. Many researches tackled those areas of research individually. However, information extraction systems should have integrated with data integration methods to make use of the extracted information. Handling uncertainty in extraction and integration process is an important issue to enhance the quality of the data in such integrated systems.
XML is al een tijdje één van de hypes. Alles moet met XML. Als kritisch informaticus begint het d... more XML is al een tijdje één van de hypes. Alles moet met XML. Als kritisch informaticus begint het dan bij mij te kriebelen. Hoezo alles moet met XML? Klinkt een beetje als ik heb een hamer en alles ziet er ineens uit als een spijker. Het kan toch niet waar zijn dat men werkelijk iets heeft uitgevonden dat een oplossing is voor al onze problemen? In dit artikel wil ik een aantal van applicatiegebieden de revue laten passeren en eens kritisch bekijken of het wel allemaal goud is wat er blinkt.
This paper addresses two problems with toponym extraction and disambiguation. First, almost no ex... more This paper addresses two problems with toponym extraction and disambiguation. First, almost no existing works examine the extraction and disambiguation interdependency. Second, existing disambiguation techniques mostly take as input extracted toponyms without considering the uncertainty and imperfection of the extraction process. It is the aim of this paper to investigate both avenues and to show that explicit handling of the uncertainty of annotation has much potential for making both extraction and disambiguation more robust.
Abstract This position paper proposes an interactive approach for developing information extracto... more Abstract This position paper proposes an interactive approach for developing information extractors based on the ontology definition process with knowledge about possible (in) correctness of annotations. We discuss the problem of managing and manipulating probabilistic dependencies.
Abstract Een recente ontwikkeling in het databaseonderzoek betret zogenaamde'onzekere databases'.... more Abstract Een recente ontwikkeling in het databaseonderzoek betret zogenaamde'onzekere databases'. Dit artikel beschrijft wat onzekere databases zijn, hoe ze gebruikt kunnen worden en welke toepassingen met name voordeel zouden kunnen hebben van deze technologie.
Abstract Data interoperability encompasses the many data management activities needed for effecti... more Abstract Data interoperability encompasses the many data management activities needed for effective information management in anyones or any organizations everyday work such as data cleaning, coupling, fusion, mapping, and information extraction. It is our conviction that a significant amount of money and time in IT that is devoted to these activities, is about dealing with one problem:“semantic uncertainty”. Sometimes data is subjective, incomplete, not current, or incorrect, sometimes it can be interpreted in different ways, etc.
Problem statement Suppose that we are to build one information system (database, say) for several... more Problem statement Suppose that we are to build one information system (database, say) for several users that each have their own view of the world. The idea is to integrate the views of all individual users into one view (which is satisfactory for all users), and build the information system for that view. The problem that we are faced with is this:
From 19.11. 2006 to 22.11. 2006, the Dagstuhl Seminar 06472``XQuery Implementation Paradigms''was... more From 19.11. 2006 to 22.11. 2006, the Dagstuhl Seminar 06472``XQuery Implementation Paradigms''was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general.
At present, many information sources are available wherever you are. Most of the time, the inform... more At present, many information sources are available wherever you are. Most of the time, the information needed is spread across several of those information sources. Gathering this information is a tedious and time consuming job. Automating this process would assist the user in its task. Integration of the information sources provides a global information source with all information needed present. All of these information sources also change over time.
In order to meet demands in the context of Technical Information Systems (TIS) pertaining to reli... more In order to meet demands in the context of Technical Information Systems (TIS) pertaining to reliability, extensibility, maintainability, etc., we have developed an architectural framework with accompanying methodological guidelines for designing such systems. With the framework, we aim at complex multiapplication information systems using a repository to share data among applications.
Abstract This report gives an overview of my publications by topic. As such, it can serve as a re... more Abstract This report gives an overview of my publications by topic. As such, it can serve as a reading guide. Keywords: Data interoperability, data integration, probabilistic databases, objcet-oriented databases, information extraction, named entity recognition and disambiguation, entity resolution, data cleaning.
After the Twente Data Management workshop on Uncertainty in Databases held at the university of T... more After the Twente Data Management workshop on Uncertainty in Databases held at the university of Twente in June 2006, the speakers and participants expressed their wish for a workshop on the same topic colocated with a large, international conference. This Management of Uncertain Data workshop, colocated with the international conference on Very Large DataBases (VLDB) is the result of this wish. We received 9 submissions from all over the world.
Summary: The Opaque project focuses on query optimization for relational XQuery engines. Advances... more Summary: The Opaque project focuses on query optimization for relational XQuery engines. Advances in techniques for storage and query processing for XML using existing relational engines show that this approach has great potential for being able to manage the ever growing volumes of XML data. Many storage models, index structures, and algorithms have been proposed to speed up queries.
Public road authorities and private mobility service providers need information derived from the ... more Public road authorities and private mobility service providers need information derived from the current and predicted traffic states to act upon the daily urban system and its spatial and temporal dynamics. In this research, a real-time parking area state (occupancy, in- and outflux) prediction model (up to 60 minutes ahead) has been developed using publicly available historic and real time data sources. Based on a case study in a real-life scenario in the city of Arnhem, a Neural Network-based approach outperforms a Random Forest-based one on all assessed performance measures, although the differences are small. Both are outperforming a naive seasonal random walk model. Although the performance degrades with increasing prediction horizon, the model shows a performance gain of over 150% at a prediction horizon of 60 minutes compared with the naive model. Furthermore, it is shown that predicting the in- and outflux is a far more difficult task (i.e. performance gains of 30%) which n...
Abstract In this technical report we propose algorithms for implementing the axes for element nod... more Abstract In this technical report we propose algorithms for implementing the axes for element nodes in XPath given a DOM-like representation of the document. First, we construct algorithms for evaluating simple step expressions, withoout any (positional) predicates. The time complexity of these algorithms is at most O (l+ m) where l is the size of the input list and m the size of the output list.
Abstract In this document the design of a system capable of scouting and mapping an environment u... more Abstract In this document the design of a system capable of scouting and mapping an environment using a LEGO robot is described. This is achieved by building a LEGO robot that can drive around freely and take spatial measurements of the environment using a distance sensor mounted on top of it in a radar-like setup. The robot has problems achieving the required movement precision for the demanded map detail.
Abstract The usage of social networks sites (SNSs), such as Facebook, and geosocial networks (GSN... more Abstract The usage of social networks sites (SNSs), such as Facebook, and geosocial networks (GSNs), such as Foursquare, has increased tremendously over the past years. The willingness of users to share their current locations and experiences facilitate the creation of geographical recommender systems based on user generated content (UGC).
Welcome to the second Twente Data Management Workshop. The topic of this second edition is Uncert... more Welcome to the second Twente Data Management Workshop. The topic of this second edition is Uncertainty in Databases. This topic has gained more and more attention these last years. This is clearly visible by the increasing number of workshops on, or related to this topic.
1. INTRODUCTION Accessing information is an essential factor in decision making processes occurri... more 1. INTRODUCTION Accessing information is an essential factor in decision making processes occurring in different domains. Therefore, broadening the coverage of available information for the decision makers is of a vital importance. In such a informationthirsty environment, accessing every source of information is considered highly valuable. Nowadays, the main or the most general approach for finding and accessing information sources is searching queries over general search engines such as Google, Yahoo, or Bing.
Abstract Information Extraction, data Integration, and uncertain data management are different ar... more Abstract Information Extraction, data Integration, and uncertain data management are different areas of research that got vast focus in the last two decades. Many researches tackled those areas of research individually. However, information extraction systems should have integrated with data integration methods to make use of the extracted information. Handling uncertainty in extraction and integration process is an important issue to enhance the quality of the data in such integrated systems.
XML is al een tijdje één van de hypes. Alles moet met XML. Als kritisch informaticus begint het d... more XML is al een tijdje één van de hypes. Alles moet met XML. Als kritisch informaticus begint het dan bij mij te kriebelen. Hoezo alles moet met XML? Klinkt een beetje als ik heb een hamer en alles ziet er ineens uit als een spijker. Het kan toch niet waar zijn dat men werkelijk iets heeft uitgevonden dat een oplossing is voor al onze problemen? In dit artikel wil ik een aantal van applicatiegebieden de revue laten passeren en eens kritisch bekijken of het wel allemaal goud is wat er blinkt.
This paper addresses two problems with toponym extraction and disambiguation. First, almost no ex... more This paper addresses two problems with toponym extraction and disambiguation. First, almost no existing works examine the extraction and disambiguation interdependency. Second, existing disambiguation techniques mostly take as input extracted toponyms without considering the uncertainty and imperfection of the extraction process. It is the aim of this paper to investigate both avenues and to show that explicit handling of the uncertainty of annotation has much potential for making both extraction and disambiguation more robust.
Abstract This position paper proposes an interactive approach for developing information extracto... more Abstract This position paper proposes an interactive approach for developing information extractors based on the ontology definition process with knowledge about possible (in) correctness of annotations. We discuss the problem of managing and manipulating probabilistic dependencies.
Abstract Een recente ontwikkeling in het databaseonderzoek betret zogenaamde'onzekere databases'.... more Abstract Een recente ontwikkeling in het databaseonderzoek betret zogenaamde'onzekere databases'. Dit artikel beschrijft wat onzekere databases zijn, hoe ze gebruikt kunnen worden en welke toepassingen met name voordeel zouden kunnen hebben van deze technologie.
Abstract Data interoperability encompasses the many data management activities needed for effecti... more Abstract Data interoperability encompasses the many data management activities needed for effective information management in anyones or any organizations everyday work such as data cleaning, coupling, fusion, mapping, and information extraction. It is our conviction that a significant amount of money and time in IT that is devoted to these activities, is about dealing with one problem:“semantic uncertainty”. Sometimes data is subjective, incomplete, not current, or incorrect, sometimes it can be interpreted in different ways, etc.
Problem statement Suppose that we are to build one information system (database, say) for several... more Problem statement Suppose that we are to build one information system (database, say) for several users that each have their own view of the world. The idea is to integrate the views of all individual users into one view (which is satisfactory for all users), and build the information system for that view. The problem that we are faced with is this:
From 19.11. 2006 to 22.11. 2006, the Dagstuhl Seminar 06472``XQuery Implementation Paradigms''was... more From 19.11. 2006 to 22.11. 2006, the Dagstuhl Seminar 06472``XQuery Implementation Paradigms''was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general.
At present, many information sources are available wherever you are. Most of the time, the inform... more At present, many information sources are available wherever you are. Most of the time, the information needed is spread across several of those information sources. Gathering this information is a tedious and time consuming job. Automating this process would assist the user in its task. Integration of the information sources provides a global information source with all information needed present. All of these information sources also change over time.
In order to meet demands in the context of Technical Information Systems (TIS) pertaining to reli... more In order to meet demands in the context of Technical Information Systems (TIS) pertaining to reliability, extensibility, maintainability, etc., we have developed an architectural framework with accompanying methodological guidelines for designing such systems. With the framework, we aim at complex multiapplication information systems using a repository to share data among applications.
Abstract This report gives an overview of my publications by topic. As such, it can serve as a re... more Abstract This report gives an overview of my publications by topic. As such, it can serve as a reading guide. Keywords: Data interoperability, data integration, probabilistic databases, objcet-oriented databases, information extraction, named entity recognition and disambiguation, entity resolution, data cleaning.
After the Twente Data Management workshop on Uncertainty in Databases held at the university of T... more After the Twente Data Management workshop on Uncertainty in Databases held at the university of Twente in June 2006, the speakers and participants expressed their wish for a workshop on the same topic colocated with a large, international conference. This Management of Uncertain Data workshop, colocated with the international conference on Very Large DataBases (VLDB) is the result of this wish. We received 9 submissions from all over the world.
Summary: The Opaque project focuses on query optimization for relational XQuery engines. Advances... more Summary: The Opaque project focuses on query optimization for relational XQuery engines. Advances in techniques for storage and query processing for XML using existing relational engines show that this approach has great potential for being able to manage the ever growing volumes of XML data. Many storage models, index structures, and algorithms have been proposed to speed up queries.
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