TY - JOUR AB - Spiral patterns have been observed experimentally, numerically, and theoretically in a variety of systems. It is often believed that these spiral wave patterns can occur only in systems of reaction–diffusion equations. We show, both theoretically (using Hopf bifurcation techniques) and numerically (using both direct simulation and continuation of rotating waves) that spiral wave patterns can appear in a single reaction–diffusion equation [ in u(x, t)] on a disk, if one assumes "spiral" boundary conditions (ur = muθ). Spiral boundary conditions are motivated by assuming that a solution is infinitesimally an Archimedian spiral near the boundary. It follows from a bifurcation analysis that for this form of spirals there are no singularities in the spiral pattern (technically there is no spiral tip) and that at bifurcation there is a steep gradient between the "red" and "blue" arms of the spiral. AU - Dellnitz, Michael AU - Golubitsky, Martin AU - Hohmann, Andreas AU - Stewart, Ian ID - 16551 JF - International Journal of Bifurcation and Chaos SN - 0218-1274 TI - Spirals in Scalar Reaction–Diffusion Equations ER - TY - JOUR AU - Breslauer, Dany AU - Czumaj, Artur AU - Dubhashi, Devdatt P. AU - Meyer auf der Heide, Friedhelm ID - 16566 JF - Information Processing Letters SN - 0020-0190 TI - Transforming comparison model lower bounds to the parallel-random-access-machine ER - TY - CHAP AU - Golubitsky, Martin AU - Marsden, Jerrold AU - Stewart, Ian AU - Dellnitz, Michael ID - 16611 SN - 9780821803264 T2 - Normal Forms and Homoclinic Chaos TI - The constrained Liapunov-Schmidt procedure and periodic orbits ER - TY - CHAP AU - Meyer auf der Heide, Friedhelm AU - Vöcking, Berthold ID - 16704 SN - 0302-9743 T2 - STACS 95 TI - A packet routing protocol for arbitrary networks ER - TY - CHAP AU - Czumaj, Artur AU - Meyer auf der Heide, Friedhelm AU - Stemann, Volker ID - 16705 SN - 0302-9743 T2 - Lecture Notes in Computer Science TI - Shared memory simulations with triple-logarithmic delay ER - TY - CONF AU - Meyer auf der Heide, Friedhelm AU - Storch, Martin AU - Wanka, Rolf ID - 16706 SN - 0897917170 T2 - Proceedings of the seventh annual ACM symposium on Parallel algorithms and architectures - SPAA '95 TI - Optimal trade-offs between size and slowdown for universal parallel networks ER - TY - CONF AU - Czumaj, Artur AU - Meyer auf der Heide, Friedhelm AU - Stemann, Volker ID - 16707 SN - 0818669152 T2 - Proceedings Third Israel Symposium on the Theory of Computing and Systems TI - Improved optimal shared memory simulations, and the power of reconfiguration ER - TY - CHAP AU - Meyer auf der Heide, Friedhelm AU - Westermann, Matthias ID - 16717 SN - 0302-9743 T2 - Graph-Theoretic Concepts in Computer Science TI - Hot-potato routing on multi-dimensional tori ER - TY - CHAP AU - Bäumker, Armin AU - Dittrich, Wolfgang AU - Meyer auf der Heide, Friedhelm ID - 16874 SN - 0302-9743 T2 - Lecture Notes in Computer Science TI - Truly efficient parallel algorithms: c-optimal multisearch for an extension of the BSP model ER - TY - JOUR AU - Platzner, Marco AU - Rinner, Bernhard AU - Weiss, Reinhold ID - 10610 JF - J.UCS Journal of Universal Computer Science TI - Exploiting Parallelism in Constraint Satisfaction for Qualitative Simulation VL - 12 ER - TY - CONF AB - Clustering techniques have been integrated at different levels into the training procedure of a continuous-density hidden Markov model (HMM) speech recognizer. These clustering techniques can be used in two ways. First acoustically similar states are tied together. It will help to reduce the number of parameters but also allow to train otherwise rarely seen states together with more robust ones (state-tying). Secondly densities are clustered across states, this reduces the number of densities while at the same time keeping the best performances of our recognizer (density-clustering). We have applied these techniques both to word-based small-vocabulary and phoneme-based large-vocabulary recognition tasks. On the WSJ task, we could achieve a reduction of the word error rate by 7%. On the TI/NIST-connected digit task, the number of parameters was reduced by a factor 2-3 while keeping the same string error rate. AU - Dugast, Christian AU - Beyerlein, Peter AU - Haeb-Umbach, Reinhold ID - 11757 T2 - ICASSP, Detroit TI - Application of Clustering Techniques to Mixture Density Modelling for Continuous-Speech Recognition ER - TY - JOUR AB - Today speech recognition of a small vocabulary can be realized so cost-effectively that the technology can penetrate into consumer electronics. But, as first applications that failed on the market show, it is by no means obvious how to incorporate voice control in a user interface. This paper addresses the issue of how to design a voice control so that the user perceives it as a benefit. User interface guidelines that are adapted or specific to voice control are presented. Then the process of designing a voice control in the user-centred approach is described. By means of two examples, the car stereo and telephone answering machine, it is shown how this is turned into practice. AU - Gamm, Stephan AU - Haeb-Umbach, Reinhold ID - 11764 JF - Philips Journal of Research TI - User interface design of voice controlled consumer electronics ER - TY - CONF AU - Gamm, Stephan AU - Haeb-Umbach, Reinhold ID - 11765 T2 - Eurospeech, Madrid TI - Human Factors of a Voice-Controlled Car Stereo ER - TY - CONF AU - Gamm, Stephan AU - Haeb-Umbach, Reinhold AU - Langmann, Det ID - 11768 T2 - International Symposium on Human Factors in Telecommunications, Melbourne TI - The Usability Engineering of a Voice-Controlled Answering Machine ER - TY - JOUR AB - Recognition accuracy has been the primary objective of most speech recognition research, and impressive results have been obtained, e.g. less than 0.3% word error rate on a speaker-independent digit recognition task. When it comes to real-world applications, robustness and real-time response might be more important issues. For the first requirement we review some of the work on robustness and discuss one specific technique, spectral normalization, in more detail. The requirement of real-time response has to be considered in the light of the limited hardware resources in voice control applications, which are due to the tight cost constraints. In this paper we discuss in detail one specific means to reduce the processing and memory demands: a clustering technique applied at various levels within the acoustic modelling. AU - Haeb-Umbach, Reinhold AU - Beyerlein, Peter AU - Geller, Dieter ID - 11786 JF - Philips Journal of Research TI - Speech recognition algorithms for voice control interfaces ER - TY - CONF AB - We address the problem of automatically finding an acoustic representation (i.e. a transcription) of unknown words as a sequence of subword units, given a few sample utterances of the unknown words, and an inventory of speaker-independent subword units. The problem arises if a user wants to add his own vocabulary to a speaker-independent recognition system simply by speaking the words a few times. Two methods are investigated which are both based on a maximum-likelihood formulation of the problem. The experimental results show that both automatic transcription methods provide a good estimate of the acoustic models of unknown words. The recognition error rates obtained with such models in a speaker-independent recognition task are clearly better than those resulting from separate whole-word models. They are comparable with the performance of transcriptions drawn from a dictionary. AU - Haeb-Umbach, Reinhold AU - Beyerlein, P. AU - Thelen, E. ID - 11787 T2 - ICASSP, Detroit TI - Automatic Transcription of Unknown Words in a Speech Recognition System ER - TY - JOUR AB - This paper gives an overview of the Philips Research system for continuous-speech recognition. The recognition architecture is based on an integrated statistical approach. The system has been successfully applied to various tasks in American English and German, ranging from small vocabulary tasks to very large vocabulary tasks and from recognition only to speech understanding. Here, we concentrate on phoneme-based continuous-speech recognition for large vocabulary recognition as used for dictation, which covers a significant part of our research work on speech recognition. We describe this task and report on experimental results. In order to allow a comparison with the performance of other systems, a section with an evaluation on the standard North American Business news (NAB2) task (dictation of American English newspaper text) is supplied. AU - Steinbiss, Volker AU - Ney, Hermann J. AU - Aubert, Xavier L. AU - Besling, Stefan AU - Dugast, Christian AU - Essen, Ute AU - Geller, Dieter AU - Haeb-Umbach, Reinhold AU - Kneser, Reinhard AU - Meier, Hans Günter AU - Oerder, Martin AU - Tran, Bach Hiep ID - 11905 JF - Philips Journal of Research TI - The Philips Research system for continuous-speech dictation ER - TY - JOUR AB - This paper gives an overview of the Philips research system for phoneme-based, large-vocabulary, continuousspeech recognition. The system has been successfully applied to various tasks in the German and (American) English languages, ranging from small vocabulary tasks to very large vocabulary tasks. Here, we concentrate on continuousspeech recognition for dictation in real applications, the dictation of legal reports and radiology reports in German. We describe this task and report on experimental results. We also describe a commercial PC-based dictation system which includes a PC implementation of our scientific recognition prototype. In order to allow for a comparison with the performance of other systems, a section with an evaluation on the standard Wall Street Journal task (dictation of American English newspaper text) is supplied. The recognition architecture is based on an integrated statistical approach. We describe the characteristic features of the system as opposed to other systems: 1. the Viterbi criterion is consistently applied both in training and testing; 2. continuous mixture densities are used without tying or smoothing; 3. time-synchronous beam search in connection with a phoneme look-ahead is applied to a tree-organized lexicon. AU - Steinbiss, Volker AU - Ney, Hermann J. AU - Essen, Ute AU - Tran, Bach Hiep AU - Aubert, Xavier L. AU - Dugast, Christian AU - Kneser, Reinhard AU - Meier, Hans Günter AU - Oerder, Martin AU - Haeb-Umbach, Reinhold AU - Geller, Dieter AU - Hoellerbauer, W. AU - Bartosik, H. ID - 11948 JF - Speech Communication TI - Continuous speech dictation - From theory to practice ER - TY - GEN AU - Hellebrand, Sybille AU - Wunderlich, Hans-Joachim ID - 13026 TI - Synthesis Procedures for Self-Testable Controllers ER - TY - GEN AU - Hellebrand, Sybille AU - Wunderlich, Hans-Joachim AU - Goncalves, F. AU - Paulo Teixeira, Joao ID - 13027 TI - Evaluation of Self-Testable Controller Architectures Based on Realistic Fault Analysis ER -