Dr. rer. nat.

Hecker, Dirk

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Extracting Movement-based Topics for Analysis of Space Use

2023 , Andriyenko, Gennadiy , Andriyenko, Nathaliya , Hecker, Dirk

We present a novel approach to analyze spatio-temporal movement patterns using topic modeling. Our approach represents trajectories as sequences of place visits and moves, applies topic modeling separately to each collection of sequences, and synthesizes results. This supports the identification of dominant topics for both place visits and moves, the exploration of spatial and temporal patterns of movement, enabling understanding of space use. The approach is applied to two real-world data sets of car movements in Milan and UK road traffic, demonstrating the ability to uncover meaningful patterns and insights.

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A QUBO Formulation of the k-Medoids Problem

2019 , Bauckhage, Christian , Piatkowski, Nico , Sifa, Rafet , Hecker, Dirk , Wrobel, Stefan

We are concerned with k-medoids clustering and propose aquadratic unconstrained binary optimization (QUBO) formulation of the problem of identifying k medoids among n data points without having to cluster the data. Given our QUBO formulation of this NP-hard problem, it should be possible to solve it on adiabatic quantum computers.

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Analyzing temporal usage patterns of street segments based on GPS data - a case study in Switzerland

2012 , Schreinemacher, Jutta , Körner, Christine , Hecker, Dirk , Bareth, Georg

Mobility has become a key component of our social and economic activities. Depending on our activities, the usage of the road network varies, showing, for example, an increased traffic load in early morning when people go to work. Such usage patterns are of interest not only for traffic management but also for private companies offering location-based services. In this paper we analyze the temporal usage of street segments based on a large GPS data set in Switzerland. We first conduct a clustering analysis which detects groups of segments with similar temporal usage patterns. Afterwards we analyze the patterns with respect to their temporal and spatial characteristics. Our analysis shows that GPS data is qualified for an analysis of temporal usage patterns, identifying shopping and leisure activities.

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Analytical workflow of monitoring human mobility in big event settings using bluetooth

2011 , Stange, Hendrik , Liebig, Thomas , Hecker, Dirk , Andrienko, Gennady , Andrienko, Natalia

In recent times, consumer research at major social events received significant interest by organizing companies. Understanding the movements and motivations of the customers enables new business strategies and is needed to minimize the risk of investment. The spatiotemporal complexity of major events poses high demands on survey and analytical methods. New technological advances in both event monitoring systems and evaluation methods of movement data provide new insights into the behavioral patterns of customers by preserving their privacy. In this paper we present a work that seeks to systematize the research process of design, collection, and analysis of visitor behavior in a mixed indoor-outdoor event setting using Bluetooth sensor technology. The defined workow is comprised of 5 steps and designed to answer heterogeneous business questions with respect to customer movement behavior in a single event context. Our approach is applied in a real-world business applicati on for a Formula 1 event.

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tanh Neurons are Bayesian Decision Makers

2021 , Bauckhage, Christian , Sifa, Rafet , Hecker, Dirk

The hyperbolic tangent (tanh) is a traditional choice for the activation function of the neurons of an artificial neural network. Here, we go through a simple calculation that shows that this modeling choice is linked to Bayesian decision theory. Our brief, tutorial-like discussion is intended as a reference to an observation rarely mentioned in standard textbooks.

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Detecting Mobility Patterns with Stationary Bluetooth Sensors: A real-world Case Study

2015 , Müller, Marc , Schulz, Daniel , Mock, Michael , Hecker, Dirk

A Bluetooth sensor network was built up in the city of Bonn to measure Bluetooth MAC-addresses. The results of the acquired data are separated on a macro level and mobility patterns. We have collected nearly 5 million data points from 14 distinct stationary sensors over a period of 1 month and recognized over 85.000 unique devices. We show that the data is sufficiently dense to detect commuter patterns based on a Fourier analysis. In addition, we discuss limitations found in the dataset and present lessons learned.

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Analyse von raumzeitlichen Bewegungsmustern auf Basis von Bluetooth-Sensoren

2012 , Ellersiek, Timothy , Liebig, Thomas , Hecker, Dirk , Kopp, Christine

Informationen über das Kundenverhalten sind ein wesentlicher Forschungsbestandteil im Bereich des Marketings. Dabei hilft das Verstehen von Entscheidungsfindungsprozessendes potenziellen Kunden in einem raumzeitlichen Wechselspiel mit seiner Umgebung dem Anbieter die Qualität seines Produktes aufzuwerten. Bis vor kurzem wurden Veränderungen am Produkt häufig durch Trial-and-Error-Methoden vorgenommen; heute jedoch erlauben neuartige Technologien wie beispielsweise Bluetooth, GPS oder Video neue Möglichkeiten, dem Anbieter zielgenaue Qualitäts-Validierungen seiner Produkte durchzuführen. In dem vorliegenden Beispiel wird der vorangehende Sachverhalt auf die Mobilität im Duisburger Zoo übertragen. Repräsentative Daten über das Bewegungsverhalten der Besucher werden unter Wahrung der Privatsphäre in einem siebentägigen Versuchszeitraum anhand von Bluetooth-Tracking erfasst, anschließend aufbereitet, analysiert und interpretiert. Die Ergebnisse zeigen, dass die Reproduktion von Mobilitätsinformationendurch die Erfassung von privaten Endgeräten der Besucher mittels einer kostengünstigen Technologie wie das Bluetooth möglich ist.

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Max-Sum Dispersion via Quantum Annealing

2019 , Bauckhage, Christian , Sifa, Rafet , Hecker, Dirk , Wrobel, Stefan

We devise an Ising model for the max-sum dispersion problem which occurs in contexts such as Web search or text summarization. Given this Ising model, max-sum dispersion can be solved on adiabatic quantum computers; in proof of concept simulations, we solve the corresponding Schrödinger equations and observe our approach to work well.

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Using Bluetooth to track mobility patterns: Depicting its potential based on various case studies

2013 , Ellersiek, Timothy , Andrienko, Gennady , Andrienko, Natalia , Hecker, Dirk , Stange, Hendrik , Müller, Marc

During the past years the interest in the exploitation of mobility information has increased significantly. A growing number of companies and research institutions are interested in the analysis of mobility data with demand of a high level of spatial detail. Means of tracking persons in our environment can nowadays be fulfilled by utilizing several technologies, for example the Bluetooth technology, offering means to obtain movement data. This paper gives an overview of four case studies in the field of Bluetooth tracking which were conducted in order to provide helpful insights on movement aspects for decision makers in their specific microcosm. Aim is to analyse spatio-temporal validity of Bluetooth tracking, and in doing so, to describe the potential of Bluetooth in pedestrian mobility mining.

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Publication

Robustness analyses for repeated mobility surveys in outdoor advertising

2011 , Hecker, Dirk , Körner, Christine , May, Michael

A growing number of companies use mobility data in their day-to-day business. However, as the data grows older, new data has to be collected in order to keep applications up-to-date. Consequently, it is of great importance to know the impact that a different mobility sample may cause. This aspect of analysis has been largely neglected in mobility data mining research so far. In this paper we therefore analyze the robustness of performance measures with respect to a changed GPS sample in outdoor advertisement. The evaluation of outdoor advertising campaigns is a challenging application because it requires the evaluation of mobility data on a very fine spatial level. Thus, the application has a higher dependency on routes of individual test persons than classical mobility surveys. In our rob ustness analysis we apply bootstrapping and subsampling in order to measure the effect of a) a repeated mobility survey and b) a mobility survey of smaller size. We conduct our experiments on a real-world data set from Swiss outdoor advertising. Our results show that the effect is comparably small for a typical campaign and may be mitigated further by increasing the campaign size.

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