Indoor positioning and floor plan based ground truth: Can you really click where you are?

in 15th International Conference on Mobile and Ubiquitious Multimedia (MUM-2016) (2016, December)

The increasing accuracy of indoor positioning systems requires an appropriately accurate evaluation, which compares system outputs with the known coordinates of test locations --- the ground truth ... [more ▼]

The increasing accuracy of indoor positioning systems requires an appropriately accurate evaluation, which compares system outputs with the known coordinates of test locations --- the ground truth. Although ground truth data are rarely (if ever) tested, they are traditionally assumed to be perfectly accurate. However, even small errors introduced by inaccurate ground truth need to be taken into account for fair evaluation and comparison between modern high-resolution positioning systems. In this paper we analyze the quality of ground truth data provided by clicking on an interactive floor plan (a method employed by such classical systems as RADAR and Horus). Experimental results show that this method has high precision but low accuracy, and high systematic errors make it unsuitable for evaluation of fine-grained localization systems. [less ▲]

Eine innovative Stahlverbundlösung für komplexe innerstädtische Bauprojekte

in Stahlbau - Nachrichten (2016), 04/16

The real estate project KONS encountered a two and a half year process of demolition of an existing building and construction of a new building complex in a central, urban location of Luxembourg City ... [more ▼]

The real estate project KONS encountered a two and a half year process of demolition of an existing building and construction of a new building complex in a central, urban location of Luxembourg City opposite of the main railway station. Thereby the ambitious specifications of the investor as well as the requirements of the local authorities could be met only through a comprehensive and intelligent planning process. The complex interrelation between logistics and construction management processes, detailing and overall economic assessment found the solution of steel-composite design highly performant and efficient in every aspect. [less ▲]

Sociability-Driven User Recruitment in Mobile Crowdsensing Internet of Things Platforms

in IEEE Global Communications Conference (GLOBECOM), Washington, DC, USA, 2016 (2016, December)

The Internet of Things (IoT) paradigm makes the Internet more pervasive, interconnecting objects of everyday life, and is a promising solution for the development of next- generation services. Smart ... [more ▼]

The Internet of Things (IoT) paradigm makes the Internet more pervasive, interconnecting objects of everyday life, and is a promising solution for the development of next- generation services. Smart cities exploit the most advanced information technologies to improve and add value to existing public services. Applying the IoT paradigm to smart cities is fundamental to build sustainable Information and Communication Technology (ICT) platforms. Having citizens involved in the process through mobile crowdsensing (MCS) techniques unleashes potential benefits as MCS augments the capabilities of the platform without additional costs. Recruitment of participants is a key challenge when MCS systems assign sensing tasks to the users. Proper recruitment both minimizes the cost and maximizes the return, such as the number and the accuracy of accomplished tasks. In this paper, we propose a novel user recruitment policy for data acquisition in mobile crowdsensing systems. The policy can be employed in two modes, namely sociability-driven mode and distance-based mode. Sociability stands for the willingness of users in contributing to sensing tasks. Furthermore, we propose a novel metric to assess the efficiency of any recruitment policy in terms of the number of users contacted and the ones actually recruited. Performance evaluation, conducted in a real urban environment for a large number of participants, reveals the effectiveness of sociability-driven user recruitment as the average number of recruited users improves by at least a factor of two. [less ▲]

Uncertainty quantification for soft tissue biomechanics

Poster (2016, December)

A three-dimensional movement analysis of the spike in fistball

in Sports (2016), 4(4), 1-12

Due to its relevancy to point scoring, the spike is considered as one of the most important skills in fistball. Biomechanical analyses of this sport are very rare. In the present study, we performed a ... [more ▼]

Due to its relevancy to point scoring, the spike is considered as one of the most important skills in fistball. Biomechanical analyses of this sport are very rare. In the present study, we performed a three-dimensional kinematic analysis of the fistball spike, which helps to specify performance parameters on a descriptive level. Recorded by four synchronized cameras (120 Hz) and linked to the motion capture software Simi Motion® 5.0, three female fistball players of the second German league (24–26 years, 1.63–1.69 m) performed several spikes under standardized conditions. Results show that the segment velocities of the arm reached their maximum successively from proximal to distal, following the principle of temporal coordination of single impulses. The wrist shows maximum speed when the fist hits the ball. The elbow joint angle performs a rapid transition from a strong flexion to a (almost) full extension; however, the extension is completed after the moment of ball impact. In contrast, the shoulder joint angle increases almost linearly until the fistball contact and decreases afterward. The findings can be used to optimize the training of the spike. [less ▲]

Linear identification of nonlinear systems: A lifting technique based on the Koopman operator

in Proceedings of the 55th IEEE Conference on Decision and Control (2016, December)

We exploit the key idea that nonlinear system identification is equivalent to linear identification of the socalled Koopman operator. Instead of considering nonlinear system identification in the state ... [more ▼]

We exploit the key idea that nonlinear system identification is equivalent to linear identification of the socalled Koopman operator. Instead of considering nonlinear system identification in the state space, we obtain a novel linear identification technique by recasting the problem in the infinite-dimensional space of observables. This technique can be described in two main steps. In the first step, similar to a component of the Extended Dynamic Mode Decomposition algorithm, the data are lifted to the infinite-dimensional space and used for linear identification of the Koopman operator. In the second step, the obtained Koopman operator is “projected back” to the finite-dimensional state space, and identified to the nonlinear vector field through a linear least squares problem. The proposed technique is efficient to recover (polynomial) vector fields of different classes of systems, including unstable, chaotic, and open systems. In addition, it is robust to noise, well-suited to model low sampling rate datasets, and able to infer network topology and dynamics. [less ▲]

Game-Theoretic Recruitment of Sensing Service Providers for Trustworthy Cloud-Centric Internet-of-Things (IoT) Applications

in IEEE Global Communications Conference (GLOBECOM) Workshops: Fifth International Workshop on Cloud Computing Systems, Networks, and Applications (CCSNA) (2016, December)

Widespread use of connected smart devices that are equipped with various built-in sensors has introduced the mobile crowdsensing concept to the IoT-driven information and communication applications ... [more ▼]

Widespread use of connected smart devices that are equipped with various built-in sensors has introduced the mobile crowdsensing concept to the IoT-driven information and communication applications. Mobile crowdsensing requires implicit collaboration between the crowdsourcer/recruiter platforms and users. Additionally, users need to be incentivized by the crowdsensing platform because each party aims to maximize their utility. Due to the participatory nature of data collection, trustworthiness and truthfulness pose a grand challenge in crowdsensing systems in the presence of malicious users, who either aim to manipulate sensed data or collaborate unfaithfully with the motivation of maximizing their income. In this paper, we propose a game-theoretic approach for trustworthiness-driven user recruitment in mobile crowdsensing systems that consists of three phases: i) user recruitment, ii) collaborative decision making on trust scores, and iii) badge rewarding. Our proposed framework incentivizes the users through a sub-game perfect equilibrium (SPE) and gamification techniques. Through simulations, we show that the platform utility can be improved by up to the order of 50\% while the average user utility can be increased by at least 15\% when compared to fully-distributed and user-centric trustworthy crowdsensing. [less ▲]

Cargo-Kulte. Magie im Zeitalter der Globalisierung.

in Zeitschrift für Interkulturelle Germanistik (2016), 2(2016), 80-89

TPTP and Beyond: Representation of Quantified Non-Classical Logics

in Benzmüller, Christoph; Otten, Jens (Eds.) ARQNL 2016. Automated Reasoning in Quantified Non-Classical Logics (2016, December)

AGM Contraction and Revision of Rules

in Journal of Logic, Language and Information (2016), 25(3), 273-297

In this paper we study AGM contraction and revision of rules using input/output logical theories. We replace propositional formulas in the AGM framework of theory change by pairs of propositional formulas ... [more ▼]

In this paper we study AGM contraction and revision of rules using input/output logical theories. We replace propositional formulas in the AGM framework of theory change by pairs of propositional formulas, representing the rule based character of theories, and we replace the classical consequence operator Cn by an input/output logic. The results in this paper suggest that, in general, results from belief base dynamics can be transferred to rule base dynamics, but that a similar transfer of AGM theory change to rule change is much more problematic. First, we generalise belief base contraction to rule base contraction, and show that two representation results of Hansson still hold for rule base contraction. Second, we show that the six so-called basic postulates of AGM contraction are consistent only for some input/output logics, but not for others. In particular, we show that the notorious recovery postulate can be satisfied only by basic output, but not by simple-minded output. Third, we show how AGM rule revision can be defined in terms of AGM rule contraction using the Levi identity. We highlight various topics for further research. [less ▲]