Advances in wireless vehicular networks present us with opportunities for developing new distributed traffic control algorithms that avoid phenomena such as abrupt phase-transitions. Towards this end, we study the problem of distributed... more
Advances in wireless vehicular networks present us with opportunities for developing new distributed traffic control algorithms that avoid phenomena such as abrupt phase-transitions. Towards this end, we study the problem of distributed traffic control in a partitioned plane where the movement of all entities (vehicles) within each partition (or cell) is controlled by a single process. We present a distributed traffic control protocol that guarantees minimum separation between vehicles at all times, even when some cell-processes fail by crashing. Once failures cease, the protocol is guaranteed to stabilize and the packets with feasible paths to the target cell make progress towards it. The algorithm relies on two general principles: local geographical routing, and temporary blocking for maintenance of safety. Our proofs use mostly assertional reasoning and may serve as a template for analyzing other distributed traffic control protocols. We also present simulation results which provide estimates of throughput as a function of velocity, safety separation, and path complexity. Further, we present simulation results to estimate throughput as a function of failure and recovery rates.
This paper describes a toolkit for synthesizing hybrid supervisory control systems starting from the popular Simulink/Stateflow modeling environment. The toolkit provides a systematic strategy for translating Simulink/Stateflow models to... more
This paper describes a toolkit for synthesizing hybrid supervisory control systems starting from the popular Simulink/Stateflow modeling environment. The toolkit provides a systematic strategy for translating Simulink/Stateflow models to hybrid automata and discrete abstraction-based algorithm for synthesizing supervisory controllers.
Cyber-physical systems bridge the gap between cyber components, typically written in software, and the physical world. Software written with traditional development practices, however, likely contains bugs or unintended interactions among... more
Cyber-physical systems bridge the gap between cyber components, typically written in software, and the physical world. Software written with traditional development practices, however, likely contains bugs or unintended interactions among components, which can result in uncontrolled and possibly disastrous physical-world interactions. Complete verification of cyber-physical systems, however, is often impractical due to outsourced development of software, cost, software created without formal models, or excessively large or complex models where the verification process becomes intractable. Rather than mandating complete modeling and verification, we advocate sandboxing of unverified cyber-physical system controllers by augmenting the system with a verified safety wrapper that can take control of the plant in order to avoid violations of formal safety properties. The focus of this work is an automatic method, based on reachability and time-bounded reachability of hybrid systems, to generate verified sandboxes. The method is shown to be both more general than previous work, and allows the trade-off of increased computation time for improved reachability accuracy. We also present an end-to-end toolkit which performs the low-level computation to generate the sandbox source code from Simulink/Stateflow models of a cyberphysical system.
Formal analysis of Simulink/Statefow (SLSF) diagrams requires association of semantics to these diagrams. In this thesis, we present a technique and the related tool called HyLink for translating a useful subclass of SLSF diagrams to... more
Formal analysis of Simulink/Statefow (SLSF) diagrams requires association of semantics to these diagrams. In this thesis, we present a technique and the related tool called HyLink for translating a useful subclass of SLSF diagrams to hybrid automata. In the absence of ocial semantics, there are two possible interpretations of these diagrams: one is based on the ideal mathematical interpretation obtained from the syntax of the building blocks and the other is based on the simulation traces generated by the simulation engine. These two interpretations lead to two dierent kinds of hybrid automata-the former gives an automaton with state-dependent transitions and the latter gives a time-triggered automaton. We show that under certain assumptions, the semantics of the latter converge to the former as the simulation step size decreases. We illustrate HyLink's translation scheme, the assumptions, and the convergence result through several case studies.
We propose a technique for generating alternative models for keywords in a hybrid hidden Markov model-artificial neural network (HMM-ANN) keyword spotting paradigm. Given a base pronunciation for a keyword from the lookup dictionary, our... more
We propose a technique for generating alternative models for keywords in a hybrid hidden Markov model-artificial neural network (HMM-ANN) keyword spotting paradigm. Given a base pronunciation for a keyword from the lookup dictionary, our algorithm generates a new model for a keyword which takes into account the systematic errors made by the neural network and avoiding those models that can be confused with other words in the language. The new keyword model improves the keyword detection rate while minimally increasing the number of false alarms.
The classic [MN55] confusion matrix experiment (16 consonants, white noise masker) was repeated by using computerized procedures, similar to those of Phatak and Allen (2007). [Consonant and vowel confusions in speech-weighted noise, J.... more
The classic [MN55] confusion matrix experiment (16 consonants, white noise masker) was repeated by using computerized procedures, similar to those of Phatak and Allen (2007). [Consonant and vowel confusions in speech-weighted noise, J. Acoust. Soc. Am. [bold 121], ...
In this paper we describe a generic architecture for single channel speech enhancement. We assume processing in frequency domain and suppression based speech enhancement methods. The framework consists of a two stage voice activity... more
In this paper we describe a generic architecture for single channel speech enhancement. We assume processing in frequency domain and suppression based speech enhancement methods. The framework consists of a two stage voice activity detector, noise variance ...
March 2007 soumisà publication Résumé. In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the... more
March 2007 soumisà publication Résumé. In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the phoneme recognizer levels. The confusions show significant structure that is similar at all levels. Some confusions also correlate with human psychoacoustic experiments in white masking noise. These structures imply that not all errors should be counted equally and that some phoneme distinctions are arbitrary. Understanding these confusion patterns can improve the performance of a recognizer by eliminating problematic phoneme distinctions. These principles are applied to a phoneme recognition system and the results show a marked improvement in the phone error rate. Confusion pattern analysis leads to a better way of choosing phoneme sets for recognition.
In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the phoneme recognizer levels. The confusions... more
In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the phoneme recognizer levels. The confusions show significant structure that is similar at all levels. Some confusions also correlate with human psychoacoustic experiments in white masking noise. These structures imply that not all errors should be counted equally and that some phoneme distinctions are arbitrary. Understanding these confusion patterns can improve the performance of a recognizer by eliminating problematic phoneme distinctions. These principles are applied to a phoneme recognition system and the results show a marked improvement in the phone error rate. Confusion pattern analysis leads to a better way of choosing phoneme sets for recognition. Index Terms: error analysis, confusion patterns, phoneme recognizer 1.
In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the phoneme recognizer levels. The confusions... more
In this paper, we analyze the confusions patterns at three places in the hybrid phoneme recognition system. The confusions are analyzed at the pronunciation, the posterior probability, and the phoneme recognizer levels. The confusions show significant structure that is similar at all levels. Some confusions also correlate with human psychoacoustic experiments in white masking noise. These structures imply that not all errors should be counted equally and that some phoneme distinctions are arbitrary. Understanding these confusion patterns can improve the performance of a recognizer by eliminating problematic phoneme distinctions. These principles are applied to a phoneme recognition system and the results show a marked improvement in the phone error rate. Confusion pattern analysis leads to a better way of choosing phoneme sets for recognition.
Confusion matrices have long been a part of psychoacoustic phoneme experimentation. Unfortu-nately truncation experimentation is rarely analyzed based on the confusion patterns. An example of confusion pattern analysis is seen in the 1955... more
Confusion matrices have long been a part of psychoacoustic phoneme experimentation. Unfortu-nately truncation experimentation is rarely analyzed based on the confusion patterns. An example of confusion pattern analysis is seen in the 1955 article by Miller ...
Voice activity detectors (VAD) are integral part of the modern speech processing, speech enhancement and speech encoding systems. One of the major problems in practical realizations is to achieve robust VAD in conditions of background... more
Voice activity detectors (VAD) are integral part of the modern speech processing, speech enhancement and speech encoding systems. One of the major problems in practical realizations is to achieve robust VAD in conditions of background noise. Most of the statistical model-based approaches employ the Gaussian assumption in the discrete Fourier transform (DFT) domain, which deviates from the real observation. In this paper, we propose a class of VAD algorithms based on several statistical models of the probability density functions of the magnitudes. In addition, we evaluate several approaches for combining the likelihoods for each frequency bin for estimation of the likelihood for the entire frame. A data corpus with in-car noise is then used to evaluate the VAD and the results are discussed.
The sound source localizer is an important part of any microphone array processing block. Its major purpose is to determine the direction of arrival of the sound source and let a beamformer aim its beam towards this direction. In... more
The sound source localizer is an important part of any microphone array processing block. Its major purpose is to determine the direction of arrival of the sound source and let a beamformer aim its beam towards this direction. In addition, the direction of arrival can be used for meetings diarization, pointing a camera, sound source separation. Multiple algorithms and approaches exist, targeting different settings and microphone arrays. In this paper we treat the sound source localizer as a classifier and use as features the phase differences and magnitude proportions in the microphone channels. To determine the proper mix, we propose a novel cost function to measure the localization capability. The resulting algorithm is fast and suitable for realtime implementations. It works well with different microphone array geometries with both omnidirectional and unidirectional microphones.
A direct current, cold, atmospheric-pressure Ar/O 2 (2%) plasma microjet (PMJ) was used to disinfect root canals in single-rooted extracted human teeth. Results showed that 98.8% Enterococcus faecalis (E. faecalis) was inactivated in 8... more
A direct current, cold, atmospheric-pressure Ar/O 2 (2%) plasma microjet (PMJ) was used to disinfect root canals in single-rooted extracted human teeth. Results showed that 98.8% Enterococcus faecalis (E. faecalis) was inactivated in 8 min. However, the seemingly cleaned root canal was reinfected after a week, possibly due to the hard-to-reach infected dentinal tubules. It was found that a 30-min PMJ treatment could effectively prevent the reinfection. This presents a simple yet effective alternative to traditional treatment of root canal infections in endodontic therapy. KEY WORDS: plasma microjet, root canal, disinfection Volume 1, Number 2, 2011 The Effect of an Atmospheric Pressure, DC Nonthermal Plasma Microjet on Tooth Root Canal, Dentinal Tubules Infection and Reinfection Prevention
The mechanisms of eukaryotic cell response to cold plasma are studied. A series of single gene mutants of eukaryotic model organism Saccharomyces cerevisiae are used to compare their sensitivity to plasma treatment with the wild type. We... more
The mechanisms of eukaryotic cell response to cold plasma are studied. A series of single gene mutants of eukaryotic model organism Saccharomyces cerevisiae are used to compare their sensitivity to plasma treatment with the wild type. We examined 12 mutants in the oxidative stress pathway and the cell cycle pathway, in which 8 are found to be hypersensitive to plasma processing. The mutated genes' roles in the two pathways are analyzed to understand the biological response mechanisms of plasma treatment. The results demonstrate that genes from both pathways are needed for the eukaryotic cells to survive the complex plasma treatment.