5 research outputs found
Sparse coding of the modulation spectrum for noise-robust automatic speech recognition
Get PDFContains fulltext :
132233.pdf (publisher's version ) (Open Access)The full modulation spectrum is a high-dimensional representation of one-dimensional audio signals. Most previous research in automatic speech recognition converted this very rich representation into the equivalent of a sequence of short-time power spectra, mainly to simplify the computation of the posterior probability that a frame of an unknown speech signal is related to a specific state. In this paper we use the raw output of a modulation spectrum analyser in combination with sparse coding as a means for obtaining state posterior probabilities. The modulation spectrum analyser uses 15 gammatone filters. The Hilbert envelope of the output of these filters is then processed by nine modulation frequency filters, with bandwidths up to 16 Hz. Experiments using the AURORA-2 task show that the novel approach is promising. We found that the representation of medium-term dynamics in the modulation spectrum analyser must be improved. We also found that we should move towards sparse classification, by modifying the cost function in sparse coding such that the class(es) represented by the exemplars weigh in, in addition to the accuracy with which unknown observations are reconstructed. This creates two challenges: (1) developing a method for dictionary learning that takes the class occupancy of exemplars into account and (2) developing a method for learning a mapping from exemplar activations to state posterior probabilities that keeps the generalization to unseen conditions that is one of the strongest advantages of sparse coding
COMPARING THE PERFORMANCEOF HOT MIX ASPHALT BASED ONMECHANISTIC - EMPIRICALPAVEMENT DESIGN GUIDE(MEPDG) AGAINST CREEP ANDCOMPUTING MINIMUM SPEED OFHEAVY VEHICLES
No full textCreeps of flexible pavement are common failures in hot climates. One of the aggravating factors in this type of failure is the speed of the vehicles. This study aims to evaluate the rutting at different speeds based on Mechanistic-Empirical approach test of the AASHTO pavement structure deals. For this purpose, 48 samples of hot mix asphalt were made in accordance with the No. 5 seed based on issue 234 of Iranian code. Samples at 40 and under stress of 100 and 200 kpa were tested, in 3 different loading times and 2 rest times. Test results and Matlab software were used to produce permanent deformation model based on the AASHTO 2002 model. As a result, the numerical model was obtained with a correlation coefficient of 0.9077. Based on the analysis carried out on the results, it was found that the most influential factor in the development of deterioration in flexible pavement is temperature and changes in loading and stress. Despite the positive effect of the increase in rest time on reducing asphalt pavement failure, this parameter can cope with the devastating effects of stress on the sample and speed deceleration of the vehicle. The growth of about 76\% in the rut depth associated with increasing loading time of 100 ms to 1000 ms was observed. Finally, to reduce damage of asphaltic pavements in the tropics, minimum speed of vehicles was determined 20 kilometers per hour
The Interplay of Tau Protein and β-Amyloid: While Tauopathy Spreads More Profoundly Than Amyloidopathy, Both Processes Are Almost Equally Pathogenic
No full textAlzheimer�s disease (AD) is a neurodegenerative disorder, in which amyloid precursor protein (APP) misprocessing and tau protein hyperphosphorylation are well-established pathogenic cascades. Despite extensive considerations, the central mediator of neuronal cell death upon AD remains under debate. Therefore, we examined the direct interplay between tauopathy and amyloidopathy processes. We employed primary culture neurons and examined pathogenic P-tau and Aβ oligomers upon hypoxia treatment by immunofluorescence and immunoblotting. We observed both tauopathy and amyloidopathy processes upon the hypoxia condition. We also applied Aβ1�42 or P-tau onto primary cultured neurons. We overexpressed P-tau in SH-SY5Y cells and found Aβ accumulation. Furthermore, adult male rats received Aβ1�42 or pathogenic P-tau in the dorsal hippocampus and were examined for 8 weeks. Learning and memory performance, as well as anxiety behaviors, were assessed by Morris water maze and elevated plus-maze tests. Both Aβ1�42 and pathogenic P-tau significantly induced learning and memory deficits and enhanced anxiety behavior after treatment 2 weeks. Aβ administration induced robust tauopathy distribution in the cortex, striatum, and corpus callosum as well as CA1. On the other hand, P-tau treatment developed Aβ oligomers in the cortex and CA1 only. Our findings indicate that Aβ1�42 and pathogenic P-tau may induce each other and cause almost identical neurotoxicity in a time-dependent manner, while tauopathy seems to be more distributable than amyloidopathy. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
