@inproceedings{11809, abstract = {{This paper presents an end-to-end training approach for a beamformer-supported multi-channel ASR system. A neural network which estimates masks for a statistically optimum beamformer is jointly trained with a network for acoustic modeling. To update its parameters, we propagate the gradients from the acoustic model all the way through feature extraction and the complex valued beamforming operation. Besides avoiding a mismatch between the front-end and the back-end, this approach also eliminates the need for stereo data, i.e., the parallel availability of clean and noisy versions of the signals. Instead, it can be trained with real noisy multichannel data only. Also, relying on the signal statistics for beamforming, the approach makes no assumptions on the configuration of the microphone array. We further observe a performance gain through joint training in terms of word error rate in an evaluation of the system on the CHiME 4 dataset.}}, author = {{Heymann, Jahn and Drude, Lukas and Boeddeker, Christoph and Hanebrink, Patrick and Haeb-Umbach, Reinhold}}, booktitle = {{Proc. IEEE Intl. Conf. on Acoustics, Speech and Signal Processing (ICASSP)}}, title = {{{BEAMNET: End-to-End Training of a Beamformer-Supported Multi-Channel ASR System}}}, year = {{2017}}, } @article{11811, abstract = {{Acoustic beamforming can greatly improve the performance of Automatic Speech Recognition (ASR) and speech enhancement systems when multiple channels are available. We recently proposed a way to support the model-based Generalized Eigenvalue beamforming operation with a powerful neural network for spectral mask estimation. The enhancement system has a number of desirable properties. In particular, neither assumptions need to be made about the nature of the acoustic transfer function (e.g., being anechonic), nor does the array configuration need to be known. While the system has been originally developed to enhance speech in noisy environments, we show in this article that it is also effective in suppressing reverberation, thus leading to a generic trainable multi-channel speech enhancement system for robust speech processing. To support this claim, we consider two distinct datasets: The CHiME 3 challenge, which features challenging real-world noise distortions, and the Reverb challenge, which focuses on distortions caused by reverberation. We evaluate the system both with respect to a speech enhancement and a recognition task. For the first task we propose a new way to cope with the distortions introduced by the Generalized Eigenvalue beamformer by renormalizing the target energy for each frequency bin, and measure its effectiveness in terms of the PESQ score. For the latter we feed the enhanced signal to a strong DNN back-end and achieve state-of-the-art ASR results on both datasets. We further experiment with different network architectures for spectral mask estimation: One small feed-forward network with only one hidden layer, one Convolutional Neural Network and one bi-directional Long Short-Term Memory network, showing that even a small network is capable of delivering significant performance improvements.}}, author = {{Heymann, Jahn and Drude, Lukas and Haeb-Umbach, Reinhold}}, journal = {{Computer Speech and Language}}, title = {{{A Generic Neural Acoustic Beamforming Architecture for Robust Multi-Channel Speech Processing}}}, year = {{2017}}, } @misc{119, author = {{Wever, Marcel Dominik}}, publisher = {{Universität Paderborn}}, title = {{{Active Learning of User Requirement Specifications in Dynamic Software Service Markets}}}, year = {{2017}}, } @article{11984, author = {{Bloessl, Bastian and Segata, Michele and Sommer, Christoph and Dressler, Falko}}, issn = {{1536-1233}}, journal = {{IEEE Transactions on Mobile Computing}}, pages = {{1162--1175}}, title = {{{Performance Assessment of IEEE 802.11p with an Open Source SDR-Based Prototype}}}, doi = {{10.1109/tmc.2017.2751474}}, year = {{2017}}, } @inproceedings{120, abstract = {{Within software engineering, requirements engineering starts from imprecise and vague user requirements descriptions and infers precise, formalized specifications. Techniques, such as interviewing by requirements engineers, are typically applied to identify the user’s needs. We want to partially automate even this first step of requirements elicitation by methods of evolutionary computation. The idea is to enable users to specify their desired software by listing examples of behavioral descriptions. Users initially specify two lists of operation sequences, one with desired behaviors and one with forbidden behaviors. Then, we search for the appropriate formal software specification in the form of a deterministic finite automaton. We solve this problem known as grammatical inference with an active coevolutionary approach following Bongard and Lipson [2]. The coevolutionary process alternates between two phases: (A) additional training data is actively proposed by an evolutionary process and the user is interactively asked to label it; (B) appropriate automata are then evolved to solve this extended grammatical inference problem. Our approach leverages multi-objective evolution in both phases and outperforms the state-of-the-art technique [2] for input alphabet sizes of three and more, which are relevant to our problem domain of requirements specification.}}, author = {{Wever, Marcel Dominik and van Rooijen, Lorijn and Hamann, Heiko}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference (GECCO)}}, pages = {{1327----1334}}, title = {{{Active Coevolutionary Learning of Requirements Specifications from Examples}}}, doi = {{10.1145/3071178.3071258}}, year = {{2017}}, } @inproceedings{12005, author = {{Eckhoff, David and Brummer, Alexander and Sommer, Christoph}}, booktitle = {{2016 IEEE Vehicular Networking Conference (VNC)}}, isbn = {{9781509051977}}, title = {{{On the impact of antenna patterns on VANET simulation}}}, doi = {{10.1109/vnc.2016.7835925}}, year = {{2017}}, } @inproceedings{12006, author = {{Eckhoff, David and Sommer, Christoph}}, booktitle = {{2016 IEEE Vehicular Networking Conference (VNC)}}, isbn = {{9781509051977}}, title = {{{Marrying safety with privacy: A holistic solution for location privacy in VANETs}}}, doi = {{10.1109/vnc.2016.7835971}}, year = {{2017}}, } @inproceedings{12014, author = {{Hagenauer, Florian and Sommer, Christoph and Higuchi, Takamasa and Altintas, Onur and Dressler, Falko}}, booktitle = {{2016 IEEE Vehicular Networking Conference (VNC)}}, isbn = {{9781509051977}}, title = {{{Poster: Using clusters of parked cars as virtual vehicular network infrastructure}}}, doi = {{10.1109/vnc.2016.7835943}}, year = {{2017}}, } @inproceedings{12015, author = {{Hagenauer, Florian and Sommer, Christoph and Higuchi, Takamasa and Altintas, Onur and Dressler, Falko}}, booktitle = {{Proceedings of the 2nd ACM International Workshop on Smart, Autonomous, and Connected Vehicular Systems and Services - CarSys '17}}, isbn = {{9781450351461}}, title = {{{Parked Cars as Virtual Network Infrastructure}}}, doi = {{10.1145/3131944.3131952}}, year = {{2017}}, } @inproceedings{12016, author = {{Hagenauer, Florian and Sommer, Christoph and Higuchi, Takamasa and Altintas, Onur and Dressler, Falko}}, booktitle = {{Proceedings of the 2nd ACM International Workshop on Smart, Autonomous, and Connected Vehicular Systems and Services - CarSys '17}}, isbn = {{9781450351461}}, title = {{{Vehicular Micro Clouds as Virtual Edge Servers for Efficient Data Collection}}}, doi = {{10.1145/3131944.3133937}}, year = {{2017}}, } @inproceedings{12018, author = {{Hardes, Tobias and Dressler, Falko and Sommer, Christoph}}, booktitle = {{2017 International Conference on Networked Systems (NetSys)}}, isbn = {{9781509043941}}, title = {{{Simulating a city-scale community network: From models to first improvements for Freifunk}}}, doi = {{10.1109/netsys.2017.7903954}}, year = {{2017}}, } @inproceedings{12019, author = {{Heinovski, Julian and Klingler, Florian and Dressler, Falko and Sommer, Christoph}}, booktitle = {{2016 IEEE Vehicular Networking Conference (VNC)}}, isbn = {{9781509051977}}, title = {{{Performance comparison of IEEE 802.11p and ARIB STD-T109}}}, doi = {{10.1109/vnc.2016.7835923}}, year = {{2017}}, } @inproceedings{12031, author = {{Klingler, Florian and Pannu, Gurjashan Singh and Sommer, Christoph and Dressler, Falko}}, booktitle = {{Proceedings of the 23rd Annual International Conference on Mobile Computing and Networking - MobiCom '17}}, isbn = {{9781450349161}}, title = {{{Poster}}}, doi = {{10.1145/3117811.3131265}}, year = {{2017}}, } @inproceedings{12032, author = {{Klingler, Florian and Pannu, Gurjashan Singh and Sommer, Christoph and Bloessl, Bastian and Dressler, Falko}}, booktitle = {{Proceedings of the 15th Annual International Conference on Mobile Systems, Applications, and Services - MobiSys '17}}, isbn = {{9781450349284}}, title = {{{Poster}}}, doi = {{10.1145/3081333.3089322}}, year = {{2017}}, } @inproceedings{12074, author = {{Turcanu, Ion and Sommer, Christoph and Baiocchi, Andrea and Dressler, Falko}}, booktitle = {{2016 IEEE Vehicular Networking Conference (VNC)}}, isbn = {{9781509051977}}, title = {{{Pick the right guy: CQI-based LTE forwarder selection in VANETs}}}, doi = {{10.1109/vnc.2016.7835938}}, year = {{2017}}, } @misc{12081, abstract = {{The invention relates to a building or enclosure termination opening and/or closing apparatus having communication signed or encrypted by means of a key, and to a method for operating such. To allow simple, convenient and secure use by exclusively authorised users, the apparatus comprises: a first and a second user terminal, with secure forwarding of a time-limited key from the first to the second user terminal being possible. According to an alternative, individual keys are generated by a user identification and a secret device key.}}, author = {{Jacob, Florian and Schmalenstroeer, Joerg}}, title = {{{Building or Enclosure Termination Closing and/or Opening Apparatus, and Method for Operating a Building or Enclosure Termination}}}, year = {{2017}}, } @inproceedings{121, abstract = {{Research on ad copy design is well-studied in the context of offline marketing. However, researchers have only recently started to investigate ad copies in the context of paid search, and have not yet explored the potential of information cues to enhance customers’ search process. In this paper we analyze the impact of an information cue on user behavior in ad copies. Contrary to prevalent advice, results suggest that reducing the number of words in an ad is not always beneficial. Users act quite differently (and unexpectedly) in response to an information cue depending on their search phrases. In turn, practitioners could leverage the observed moderating effect of an information cue to enhance paid search success. Furthermore, having detected deviating user behavior in terms of clicks and conversions, we provide first indicative evidence of a self-selection mechanism at play when paid search users respond to differently phrased ad copies.}}, author = {{Schlangenotto, Darius and Kundisch, Dennis}}, booktitle = {{Proceedings of the 50th annual Hawaii International Conference on System Sciences (HICSS), Waikoloa Village, HI, USA}}, title = {{{Achieving more by saying less? On the Moderating Effect of Information Cues in Paid Search}}}, year = {{2017}}, } @inproceedings{122, abstract = {{Current research on paid search highlights its ability to enhance both online and offline conversions. Yet, research investigating the impact of placing paid search ads on less prominent positions on subsequent consumer behavior is limited to the online environment. This paper presents a field experiment using differences-in-differences analysis to investigate whether the targeting of a less prominent ad position can be beneficial for bricks-and-mortar retailers. Results indicate that paid search advertising budgets could be allocated more efficiently by targeting less prominent ad positions, thus allowing bricks-and-mortar retailers with a limited marketing budget to increase the reach of their marketing campaign, attract more consumers to their website and achieve an overall increase in conversions. Furthermore, the pay-per-click billing mechanism allows advertisers to increase their marketing reach at no additional cost. Consequently, bricks-and-mortar retailers should consider targeting less prominent ad positions to reduce advertising costs while simultaneously enhancing advertising benefits.}}, author = {{Schlangenotto, Darius and Kundisch, Dennis and Gutt, Dominik}}, booktitle = {{Proceedings of the 38th International Conference on Information Systems (ICIS), Seoul, South Korea}}, location = {{Seoul, South Korea}}, title = {{{Achieving More by Paying Less? How Bricks-and-Mortar Retailers Can Benefit by Bidding Less Aggressively in Paid Search}}}, year = {{2017}}, } @techreport{123, author = {{Jazayeri, Bahar and Zimmermann, Olaf and Engels, Gregor and Kundisch, Dennis}}, publisher = {{Universität Paderborn}}, title = {{{A Variability Model for Store-oriented Software Ecosystems: An Enterprise Perspective (Supplementary Material)}}}, year = {{2017}}, } @inproceedings{124, abstract = {{Pioneers of today’s software industry like Salesforce and Apple have established successful ecosystems around their software platforms. Architectural knowledge of the existing ecosystems is implicit and fragmented among online documentation. In protection of intellectual property, existing documentation hardly reveals influential business strategies that affect the ecosystem structure. Thus, other platform providers can hardly learn from the existing ecosystems in order to systematically make reasonable design decisions with respect to their business strategies to create their own ecosystems. In this paper, we identify a variability model for architectural design decisions of a store-oriented software ecosystem product line from an enterprise perspective, comprising business, application, and infrastructure views. We derive the variability model from fragmentary material of existing ecosystems and a rigorous literature review using a research method based on the design science paradigm. To show its validity, we describe real-world ecosystems from diverse domains using the variability model. This knowledge helps platform providers to develop customized ecosystems or to recreate existing designs in a systematic way. This, in turn, contributes to an increase in designer and developer productivity.}}, author = {{Jazayeri, Bahar and Zimmermann, Olaf and Engels, Gregor and Kundisch, Dennis}}, booktitle = {{Proceedings of the 15th International Conference on Service Oriented Computing (ICSOC)}}, publisher = {{Springer}}, title = {{{A Variability Model for Store-oriented Software Ecosystems: An Enterprise Perspective}}}, doi = {{10.1007/978-3-319-69035-3_42}}, volume = {{10601}}, year = {{2017}}, }