References of "Sorger, Ulrich 50003123"
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See detailCrowdsensed Data Learning-Driven Prediction of Local Businesses Attractiveness in Smart Cities
Capponi, Andrea UL; Vitello, Piergiorgio UL; Fiandrino, Claudio UL et al

in IEEE Symposium on Computers and Communications (ISCC), Barcelona, Spain, 2019 (2019, July)

Urban planning typically relies on experience-based solutions and traditional methodologies to face urbanization issues and investigate the complex dynamics of cities. Recently, novel data-driven ... [more ▼]

Urban planning typically relies on experience-based solutions and traditional methodologies to face urbanization issues and investigate the complex dynamics of cities. Recently, novel data-driven approaches in urban computing have emerged for researchers and companies. They aim to address historical urbanization issues by exploiting sensing data gathered by mobile devices under the so-called mobile crowdsensing (MCS) paradigm. This work shows how to exploit sensing data to improve traditionally experience-based approaches for urban decisions. In particular, we apply widely known Machine Learning (ML) techniques to achieve highly accurate results in predicting categories of local businesses (LBs) (e.g., bars, restaurants), and their attractiveness in terms of classes of temporal demands (e.g., nightlife, business hours). The performance evaluation is conducted in Luxembourg city and the city of Munich with publicly available crowdsensed datasets. The results highlight that our approach does not only achieve high accuracy, but it also unveils important hidden features of the interaction of citizens and LBs. [less ▲]

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See detailCollaborative Data Delivery for Smart City-oriented Mobile Crowdsensing Systems
Vitello, Piergiorgio; Capponi, Andrea UL; Fiandrino, Claudio UL et al

in IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, UAE, 2018 (2018, December)

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing ... [more ▼]

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing infrastructures. In typical MCS systems, sensing tasks are allocated and reported on individual-basis. In this paper, we investigate on collaboration among users for data delivery as it brings a number of benefits for both users and sensing campaign organizers and leads to better coordination and use of resources. By taking advantage from proximity, users can employ device-to-device (D2D) communications like Wi-Fi Direct that are more energy efficient than 3G/4G technology. In such scenario, once a group is set, one of its member is elected to be the owner and perform data forwarding to the collector. The efficiency of forming groups and electing suitable owners defines the efficiency of the whole collaborative-based system. This paper proposes three policies optimized for MCS that are compliant with current Android implementation of Wi-Fi Direct. The evaluation results, obtained using CrowdSenSim simulator, demonstrate that collaborative-based approaches outperform significantly individual-based approaches. [less ▲]

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See detailProceedings - 2017 ILILAS Distinguished Lectures
Bouvry, Pascal UL; Bisdorff, Raymond; Schommer, Christoph UL et al

Report (2018)

The Proceedings summarizes the 12 lectures that have taken place within the ILIAS Dinstguished Lecture series 2017. It contains a brief abstract of the talks as well as some additional information about ... [more ▼]

The Proceedings summarizes the 12 lectures that have taken place within the ILIAS Dinstguished Lecture series 2017. It contains a brief abstract of the talks as well as some additional information about each speaker. [less ▲]

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See detailA New Synchronization Method for Three - phase Grid - tied LC-Filtered Voltage Source Inverters
Kobou Ngani, Patrick UL; Hadji-Minaglou, Jean-Régis UL; De Jaeger, Emmanuel et al

in International Journal of Emerging Engineering Research and Technology (2017), 5(5), 7-15

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This ... [more ▼]

In order to identify and to track the phase angle and magnitude of the grid voltage, several synchronization methods exist, among which the phase-locked loop (PLL) algorithm is the most popular. This paper presents a new synchronization method for grid-tied voltage source inverters (VSIs) based on the intrinsic inverter synchronous reference frame. The absolute phase angle of the grid voltage is not required but its voltage direct and quadrature components into the well-known inverter frame. The advantages of this method is its low computational load with a reduced number of control parameters, as well as its robustness and effectiveness. This property makes it very convenient for embedded control systems with limited computing resources. Simulations and experimental test results are presented to prove the performance of the proposed method. [less ▲]

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See detailCrowdSenSim: a Simulation Platform for Mobile Crowdsensing in Realistic Urban Environments
Fiandrino, Claudio UL; Capponi, Andrea UL; Cacciatore, Giuseppe UL et al

in IEEE Access (2017)

Smart cities take advantage of recent ICT developments to provide added value to existing public services and improve quality of life for the citizens. The Internet of Things (IoT) paradigm makes the ... [more ▼]

Smart cities take advantage of recent ICT developments to provide added value to existing public services and improve quality of life for the citizens. The Internet of Things (IoT) paradigm makes the Internet more pervasive where objects equipped with computing, storage and sensing capabilities are interconnected with communication technologies. Because of the widespread diffusion of IoT devices, applying the IoT paradigm to smart cities is an excellent solution to build sustainable Information and Communication Technology (ICT) platforms. Having citizens involved in the process through mobile crowdsensing (MCS) techniques augments capabilities of these ICT platforms without additional costs. For proper operation, MCS systems require the contribution from a large number of participants. Simulations are therefore a candidate tool to assess the performance of MCS systems. In this paper, we illustrate the design of CrowdSenSim, a simulator for mobile crowdsensing. CrowdSenSim is designed specifically for realistic urban environments and smart cities services. We demonstrate the effectiveness of CrowdSenSim for the most popular MCS sensing paradigms (participatory and opportunistic) and we present its applicability using a smart public street lighting scenario. [less ▲]

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See detailAssessing Performance of Internet of Things-based Mobile Crowdsensing Systems for Sensing as a Service Applications in Smart Cities
Capponi, Andrea UL; Fiandrino, Claudio UL; Franck, Christian UL et al

in 8th IEEE International Conference on Cloud Computing Technology and Science (CloudCom) (2016, December)

The Internet of Things (IoT) paradigm makes the Internet more pervasive. IoT devices are objects equipped with computing, storage and sensing capabilities and they are interconnected with communication ... [more ▼]

The Internet of Things (IoT) paradigm makes the Internet more pervasive. IoT devices are objects equipped with computing, storage and sensing capabilities and they are interconnected with communication technologies. Smart cities exploit the most advanced information technologies to improve public services. For being effective, smart cities require a massive amount of data, typically gathered from sensors. The application of the IoT paradigm to smart cities is an excellent solution to build sustainable Information and Communication Technology (ICT) platforms and to produce a large amount of data following Sensing as a Service (S^2aaS) business models. Having citizens involved in the process through mobile crowdsensing (MCS) techniques unleashes potential benefits as MCS augments the capabilities of existing sensing platforms. To this date, it remains an open challenge to quantify the costs the users sustain to contribute data with IoT devices such as the energy from the batteries and the amount of data generated at city-level. In this paper, we analyze existing solutions, we provide guidelines to design a large-scale urban level simulator and we present preliminary results from a prototype. [less ▲]

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See detailSome Properties of Homogenous Trellis-Constrained Codes
Franck, Christian UL; Sorger, Ulrich UL

Poster (2016)

We consider Homogenous Trellis-Constrained Codes (HTCC), a generalization of Turbo-codes where all bits are constrained. No efficient decoding algorithm is known for these codes, so our results are ... [more ▼]

We consider Homogenous Trellis-Constrained Codes (HTCC), a generalization of Turbo-codes where all bits are constrained. No efficient decoding algorithm is known for these codes, so our results are primarily of theoretical interest. We propose a technique to derive an upper bound for the maximum-likelihood (ML) decoding of BSC errors. Our tech- nique is based on the weight distributions of the constituent codes and it can also be used when a specific number of errors e is known. We observe that with an ML-decoder some HTCC codes exhibit an error correcting performance close to that of random codes. For those codes we also observe a significant performance gap between ML-decoding and practical decoding based on belief-propagation. [less ▲]

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See detailUntraceable VoIP Communication based on DC-nets
Franck, Christian UL; Sorger, Ulrich UL

E-print/Working paper (2016)

Untraceable communication is about hiding the identity of the sender or the recipient of a message. Currently most systems used in practice (e.g., TOR) rely on the principle that a message is routed via ... [more ▼]

Untraceable communication is about hiding the identity of the sender or the recipient of a message. Currently most systems used in practice (e.g., TOR) rely on the principle that a message is routed via several relays to obfuscate its path through the network. However, as this increases the end-to-end latency it is not ideal for applications like Voice-over-IP (VoIP) communication, where participants will notice annoying delays if the data does not arrive fast enough. We propose an approach based on the paradigm of Dining Cryptographer networks (DC-nets) that can be used to realize untraceable communication within small groups. The main features of our approach are low latency and resilience to packet-loss and fault packets sent by malicious players. We consider the special case of VoIP communication and propose techniques for a P2P implementation. We expose existing problems and sketch possible future large-scale systems composed of multiple groups. [less ▲]

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See detailNonlocalization Properties of Time Operators Transformations
Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in International Journal of Theoretical Physics (2015), 54(4), 787-800

It is presented a general approach to the problem of extension of time operators and the associated Lambda transformations on singular measures. It is also shown that Lambda transformations defined on ... [more ▼]

It is presented a general approach to the problem of extension of time operators and the associated Lambda transformations on singular measures. It is also shown that Lambda transformations defined on function spaces having the Urysohn property are non localized. Particular attention has been devoted to time and Lambda operators associated with the Walsh-Paley system and to a characterization of their domain and non locality. [less ▲]

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See detailA Hidden Markov Model to detect relevance in nancial documents based on on/off topics
Kampas, Dimitrios UL; Schommer, Christoph UL; Sorger, Ulrich UL

in European Conference on Data Analysis (2014)

Automated text classification has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Most of the standard classification posit the ... [more ▼]

Automated text classification has gained a significant attention since a vast amount of documents in digital forms are widespread and continuously increasing. Most of the standard classification posit the independence of the terms-features in document, which is unrealistic considering the sophisticated structure of the language. Our research concerns the discovery of relevance in documents, which adequately refers to a sufficient number of thematic themes (or topics) that are either `on' or `off'. `On topics' are semantically close with a domain specific discourse, whereas `Off topics' are not considered to be on documents. As a rather promising approach, we have modelled a stochastic process for term sequences, where each term is conditionally dependent of its preceeding terms. Hidden Markov Models hereby provide a reliable potential to incorporate language and domain dependencies for a classification. Terms are deterministically associated with classes to improve the probability estimates for the infrequent words. In the paper presentation, we demonstrate our approach and motivate its eligibility by the exploration of annotated Thomson Reuters news documents; in particular, the `on topic' documents discourse the monetary policy of Federal Reserves. We estimate the transition and emission probabilities of our model on a training set of both on and off topic documents and evaluate the accuracy of our approach using 10-fold cross validation. This work is part of the interdisciplinary research project ESCAPE, which is funded by the Fonds National de la Recherche. We kindly thank our colleagues from the Dept. of Finance for their support. [less ▲]

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See detailDelays of Interconnected Flows
Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in International Journal of Theoretical Physics (2011), 50

A rigorous approach to flows of particles in networks is presented. Under the assumption of independence of the transversal flows the asymptotic distributions of inter-delay times between particles are ... [more ▼]

A rigorous approach to flows of particles in networks is presented. Under the assumption of independence of the transversal flows the asymptotic distributions of inter-delay times between particles are shown to be log-normal. In the case of dependent transversal traffic the ARCH and GARCH time series models, as well as martingale approach, have been applied. [less ▲]

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See detailCoherent Receiver for AIS Satellite Detection
Gallardo, M. M. A. Jurado; Sorger, Ulrich UL

in Proceedings of 4th International Symposium on Communications, Control and Signal Processing (ISCCSP) (2010)

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See detailGeneralizing the Transfer in Iterative Error Correction: Dissection Decoding
Sorger, Ulrich UL; Heim, Alex

in International Zurich Seminar on Communications (2010)

Iterative decoding with message-passing is consid- ered. The message format is generalized from the classical, single probability value for each code symbol to a probability distribu- tion by introducing ... [more ▼]

Iterative decoding with message-passing is consid- ered. The message format is generalized from the classical, single probability value for each code symbol to a probability distribu- tion by introducing an additional logarithmic probability mea- sure. Thereby, the representation of the probability distributions underlying the constituent code constraints by the messages is improved in terms of the Kullback-Leibler divergence. Simulation shows that this improvement can transfer to the error correcting performance. [less ▲]

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See detailA Lower Bound for the Minimum Distance of Intersection Codes
Franck, Christian UL; Sorger, Ulrich UL

in A Lower Bound for the Minimum Distance of Intersection Codes (2010)

Intersection codes are a superclass of Turbo- and LDPC codes. This class contains codes constructed by intersecting interleaved constituent codes. We propose a lower bound for the minimum distance of ... [more ▼]

Intersection codes are a superclass of Turbo- and LDPC codes. This class contains codes constructed by intersecting interleaved constituent codes. We propose a lower bound for the minimum distance of these codes. Using this bound, we compare intersection codes obtained from different constituent codes. [less ▲]

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See detailMultiple Decision Feedback Equalizer for Satellite AIS Coherent detection
Gallardo, Jurado UL; Sorger, Ulrich UL; Angeles, Maria

in Multiple Decision Feedback Equalizer for Satellite AIS Coherent detection (2010)

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See detailOn the Convergence of Iterative Belief Propagation
Heim, A.; Sorger, Ulrich UL

in Proc. IEEE International Symposium on Information Theory ISIT (2009)

The convergence of iterative decoding schemes utilizing belief propagation is considered. A quantitative bound for the output L-values of a Turbo decoder is given that only depends on the received word ... [more ▼]

The convergence of iterative decoding schemes utilizing belief propagation is considered. A quantitative bound for the output L-values of a Turbo decoder is given that only depends on the received word and thus is independent from the decoder iterations. Further, it is shown that the exponential increase of the L-values in each iteration within an LDPC decoder is limited by the degree of the variable nodes. [less ▲]

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See detailA Multiplicative Law of Network Traffic and Its Consequences.
Melakessou, Foued UL; Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in Acta Physica Polonica B (2009), 40(5), 1507-1525

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See detailFunctions on Probabilistic Graphical Models
Ignac, Tomasz UL; Sorger, Ulrich UL

in Proceedings of the International Multiconference on Computer Science and Information Technology IMCSIT 2009 (2009)

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See detailSlotted Packet Counting Attacks on Anonymity Protocols
Fusenig, Volker UL; Staab, Eugen UL; Sorger, Ulrich UL et al

in The proceedings of the Australasian Information Security Conference (2009)

In this paper we present a slotted packet counting attack against anonymity protocols. Common packet counting attacks make strong assumptions on the setup and can easily lead to wrong conclusions, as we ... [more ▼]

In this paper we present a slotted packet counting attack against anonymity protocols. Common packet counting attacks make strong assumptions on the setup and can easily lead to wrong conclusions, as we will show in our work. To overcome these limitations, we account for the variation of traffic load over time. We use correlation to express the relation between sender and receiver nodes. Our attack is applicable to many anonymity protocols. It assumes a passive attacker and works with partial knowledge of the network traffic. [less ▲]

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See detailHow Can Route Diversity Improve the Internet Traffic?
Melakessou, Foued UL; Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in ECTI Transactions on Electrical Engineering, Electronics, and Communications (2008), 6(2), 93105

Detailed reference viewed: 54 (0 UL)