Estimating the Potential Speedup of Computer Vision Applications on Embedded Multiprocessors

Computer vision applications constitute one of the key drivers for embedded multicore architectures. Although the number of available cores is increasing in new architectures, designing an application to maximize the utilization of the platform is still a challenge. In this sense, parallel performance prediction tools can aid developers in understanding the characteristics of an application and finding the most adequate parallelization strategy. In this work, we present a method for early parallel performance estimation on embedded multiprocessors from sequential application traces. We describe its implementation in Parana, a fast trace-driven simulator targeting OpenMP applications on the STMicroelectronics' STxP70 Application-Specific Multiprocessor (ASMP). Results for the FAST key point detector application show an error margin of less than 10% compared to the reference cycle-approximate simulator, with lower modeling effort and up to 20x faster execution time.Comment: Presented at DATE Friday Workshop on Heterogeneous Architectures and Design Methods for Embedded Image Systems (HIS 2015) (arXiv:1502.07241

Thermal stability of polymethacrylic based ELIUM® resin: Effect of comonomers, antioxidants and aluminum trihydrate filler

This paper presents the study of the thermal degradation of methyl methacrylate resin based materials known as ELIUM® resin. Samples under investigation were made from MMA based resin (ELIUM® V1), ELIUM® V1 with a dimethacrylate comonomer (ELIUM® V2), and ELIUM® V2 with a stabilizer package (ELIUM® V3). They were used for trying to discuss the degradation mechanisms. Blocks differing by their thickness made from ELIUM® formulation filled with aluminum TriHydrate used as flame retardant were also investigated in order to better match some industrial materials. Degradation was observed to be mainly driven by unzipping, consistent with the methacrylic nature of ELIUM® resin. Occurrence of oxidation is also discussed depending on materials formulation and temperature. A blend of antioxidants was inefficient for limiting mass loss. At 200 °C, both ATH and ELIUM® degrade, which contributes to overall mass loss. At temperatures below 180 °C, ATH does not seem to induce new degradation mechanisms but would increase oxygen diffusivity. Finally, a first simple kinetic model is proposed to predict mass loss in thick composite blocks aged under air

Application-level Performance Optimization: A Computer Vision Case Study on STHORM

AbstractComputer vision applications constitute one of the key drivers for embedded many-core architectures. In order to exploit the full potential of such systems, a balance between computation and communication is critical, but many computer vision algorithms present a highly data-dependent behavior that complexifies this task. To enable application performance optimization, the development environment must provide the developer with tools for fast and precise application-level performance analysis. We describe the process to port and optimize a face detection application onto the STHORM many-core accelerator using the STHORM OpenCL SDK. We identify the main factors that limit performance and discern the contributions arising from: the application itself, the OpenCL programming model, and the STHORM OpenCL SDK. Finally, we show how these issues can be addressed in the future to enable developers to further improve application performance

Oxidation and unzipping in ELIUM resin: Kinetic model for mass loss

This paper gives a first study of the thermal and thermal oxidative ageing of ELIUM® resins. Chain ends unzipping was observed to be the main degradation mechanism under nitrogen whereas an oxidation mechanism with random chain scissions is shown to predominate in presence of oxygen. A first simplified kinetic model is proposed and fits experimental results for thin films at temperatures ranging from 230 to 310°C under oxygen or nitrogen

Recommendations for motion correction of infant fNIRS data applicable to data sets acquired with a variety of experimental designs and acquisition systems

Despite motion artifacts are a major source of noise in fNIRS infant data, how to approach motion correction in this population has only recently started to be investigated. Homer2 offers a wide range of motion correction methods and previous work on simulated and adult data suggested the use of Spline interpolation and Wavelet filtering as optimal methods for the recovery of trials affected by motion. However, motion artifacts in infant data differ from those in adults' both in amplitude and frequency of occurrence. Therefore, artifact correction recommendations derived from adult data might not be the optimal for infant data. We hypothesized that the combined use of Spline and Wavelet would outperform their individual use on data with complex profiles of motion artifacts. To demonstrate this, we first compared, on infant semi-simulated data, the performance of several motion correction techniques on their own and of the novel combined approach; then, we investigated the performance of Spline and Wavelet alone and in combination on real cognitive data from three datasets collected with infants of different ages (5, 7 and 10 months), with different tasks (auditory/visual and tactile) and with different NIRS systems. To quantitatively estimate and compare the efficacy of these techniques, we adopted four metrics: hemodynamic response recovery error, within-subject standard deviation, between-subjects standard deviation and number of trials that survived each correction method. Our results demonstrated that (i) it is always better correcting for motion artifacts than rejecting the corrupted trials; (ii) Wavelet filtering on its own and in combination with Spline interpolation seems to be the most effective approach in reducing the between- and the within-subject standard deviations. Importantly, the combination of Spline and Wavelet was the approach providing the best performance in semi-simulation both at low and high levels of noise, also recovering most of the trials affected by motion artifacts across all datasets, a crucial result when working with infant data. [Abstract copyright: Copyright © 2019. Published by Elsevier Inc.

Adult-like processing of time-compressed speech by newborns: A NIRS study

none2restrictedIssard C.; Gervain J.Issard, C.; Gervain, J

Comparaison lithostratigraphique, géochimique et structurale entre la zone axiale et les nappes du versant Sud dela Montagne Noire dans le district aurifère de Salsigne (Aude, France)

No english abstractCette étude montre que le domaine para-autochtone est, en fait, un ensemble structuralement hétérogène, une juxtaposition d'unités septentrionales (zone axiale) et d'unités méridionales (nappes du versant sud). En ce qui concerne la couche minéralisée de la mine de Salsigne, l'hypothèse d'une minéralisation stratiforme volcano-sédimentaire exhalative est mise en doute, elle s'intègrerait plutôt a l'ensemble des minéralisations filoniennes du district de Salsigne

Construction d'une représentation stable de la parole chez le nouveau-né humain

We all have a different voice, our intonations change all the time, and we might have a foreign accent, but we still perceive the same syllables and the same words. Similarly, infants learn their native language from various speakers who speak with different speech rates and intonations from moment to moment. Therefore a key question is how humans manage to extract these invariant representations of speech sounds from the beginning of their life. The present thesis aims to enlighten how these invariant representations of speech are built in human newborns. In a first experiment, we presented normal speech as well as moderately (60% of initial duration) or highly compressed (30% of its initial duration) speech in the participants' native language (French). We recorded the hemodynamic response to these stimuli over the frontal, temporal and parietal cortices using NIRS. The results show no difference between normal and 60%-compressed speech, but differential responses between normal and 30%-compressed speech on the one hand, and 60% and 30%-compressed speech in a set of frontal, temporal, and temporo-parietal regions on the other hand. This provides evidence that the newborn brain responds to speech in a stable manner over a range of time-scales that is similar to adults. In a second set of experiments, we asked whether this ability relies on prenatal experience with the native language rhythmic structure. We replicated the same experiment in two unfamiliar languages, one that is rythmically similar (Spanish), and one that is rhythmically different from the native language (English). No difference between the three compression rates was observed in Spanish. In English, only 30%-compressed speech evoked significant responses in a temporo-parietal region also activated for French. This confirms that 30%-compressed speech This also shows that prenatal experience shapes auditory processing of speech at birth. In particular, prenatal experience with the prosodic or phonological structure of the language might also contribute to encode speech in a stable way, helping infants to place landmarks in the signal. To conclude, the results presented in this thesis support the idea that speech is encoded as an abstract auditory object from the first stages of auditory processing. This auditory code is further modulated by higher level linguistic processing, integrating knowledge about the subject's native language. This knowledge is acquired from intra-uterine life, enabling a stable encoding of speech, adapted to the subject's linguistic environment readily from birth.Nous avons tous une voix différente, nos intonations changent tout le temps et nous avons peut-être un accent étranger, mais nous percevons toujours les mêmes syllabes et les mêmes mots. De même, les nourrissons apprennent leur langue maternelle à partir de divers locuteurs qui parlent à des vitesses et avec des intonations variables. Par conséquent, une question clé est de savoir comment les humains parviennent à extraire ces représentations invariantes des sons de la parole dès le début de leur vie. Cette thèse vise à éclairer la manière dont ces représentations stables de la parole sont construites chez le nouveau-nés humain. Dans une première expérience, nous avons présenté de la parole normale, modérément (60% de la durée initiale) ou fortement compressé (30% de la durée initiale) dans la langue maternelle des participants. Nous avons enregistré la réponse hémodynamique à ces stimuli dans les cortex frontal, temporal et pariétal en utilisant la NIRS. Les résultats ne montrent pas de différence de réponse entre la parole compressée normale et 60%, mais des réponses différentes entre la parole normale et la parole compressée à 30% d'une part, et entre la parole compressée 60 % et à 30 % d'autre part dans un ensemble de régions frontales, temporales et temporo-pariétales. Ces résultats montrent que le cerveau du nouveau-né répond de manière stable à la parole sur une gamme d'échelles temporelles, comme ce qui a été observé chez l'adulte. Dans une deuxième série d'expériences, nous nous sommes demandé si cette capacité repose sur l'expérience prénatale avec la structure rythmique de la langue maternelle. Nous avons reproduit la même expérience dans deux langues inconnues, une rythmiquement similaire (l'espagnol) et une autre rythmiquement différente de la langue maternelle (l'anglais). Aucune différence entre les trois taux de compression n'a été observée en espagnol. En anglais, seule la parole fortement compressée évoquait des réponses significatives dans une région temporo-pariétale également activée pour le français. Cela confirme que la parole fortement compressée est traitée de façon différente par le cerveau du nouveau-né. Cela montre également que l'expérience prénatale façonne le traitement auditif de la parole à la naissance. En particulier, l'expérience prénatale de la structure prosodique ou phonologique de la langue maternelle contribue à encoder la parole de manière stable, potentiellement en aidant les nourrissons à placer des repères dans le signal. Pour conclure, les résultats présentés dans cette thèse soutiennent l'idée que la parole est encodée comme un objet auditif abstrait, dès les étapes de traitement auditif. Ce code est par la suite modulé par les étapes de traitement linguistique, intégrant les connaissances du sujet sur sa langue maternelle. Ces connaissances sont acquises dès la vie intra-utérine, permettant dès la naissance d'encoder la parole de façon robuste et adaptée à l'environnement linguistique

Problèmes aux valeurs propres non linéaires dans les inéquations variaionnelles : Etude locale

ON S'INTERESSE A UNE CLASSE D'INEQUATIONS VARIATIONNELLES ELLIPTIQUES, ASSOCIEES A UN PROBLEME D'OBSTACLE ET DEPENDANT D'UN PARAMETRE LAMBDA : A(A,V-U) >OU= SOM::(OMEGA )LAMBDA F(U)(V-U)DX POUR TOUT V APPARTIENT A K, U APPARTIENT A K=(W APPARTIENT A H::(0)**(1)(OMEGA )/W OU= PSI P.P. SUR OMEGA ). UNE TELLE INEQUATION ADMET AU MOINS UNE BRANCHE DE SOLUTIONS EQUATION ET UNE BRANCHE DE SOLUTIONS INEQUATIONS. ON CHERCHE A CONNAITRE LA STRUCTURE LOCALE DES BRANCHES INEQUATIONS. GRACE A UN PROCESSUS DE LINEARISATION "CONIQUE" ON CLASSE LES POINTS DE LA BRANCHE INEQUATION EN POINTS REGULIERS OU SINGULIERS. AU VOISINAGE D'UN POINT REGULIER, ON MONTRE QUE LES SOLUTIONS ADMETTENT UN DEVELOPPEMENT SELON LAMBDA . PUIS ON ETUDIE LE COMPORTEMENT LOCAL DES SOLUTIONS AU VOISINAGE D'UN POINT SINGULIER VERIFIANT CERTAINES HYPOTHESES, QUI SONT A RAPPROCHER DE CELLES FAITES POUR LES EQUATIONS ET QUI ASSURENT QU'ON A DU POINT DE RETOURNEMENT. ON MONTRE QUE, DANS CERTAINS CAS, IL EXISTE UN TEL POINT SINGULIER, SUR LA BRANCHE DE SOLUTIONS MAXIMALES. LES BRANCHES EQUATIONS ET INEQUATIONS SONT RELIEES PAR UN POINT APPELE POINT DE TRANSITION. ON FAIT UNE ETUDE PLUS FINE AU VOISINAGE DE CE POINT. UNE ETUDE DES DIVERSES CONDITIONS INTRODUITES POUR L'ETUDE LOCALE, MONTRE QU'ELLES SONT FORTEMENT LIEES A UNE CONDITION TYPE STABILITE. ILLUSTRATION NUMERIQUE SUR QUELQUES PROBLEMES D'OBSTACLENo abstrac

Variability of the hemodynamic response in infants: Influence of experimental design and stimulus complexity

Measuring brain activity in developmental populations remains a major challenge despite great technological advances. Among the numerous available methods, functional near-infrared spectroscopy (fNIRS), an imaging modality that probes the hemodynamic response, is a powerful tool for recording brain activity in a great variety of situations and populations. Neurocognitive studies with infants have often reported inverted hemodynamic responses, i.e. a decrease instead of an increase in regional blood oxygenation, but the exact physiological explanation and cognitive interpretation of this response remain unclear. Here, we first provide an overview of the basic principles of NIRS and its use in cognitive developmental neuroscience. We then review the infant fNIRS literature to show that the hemodynamic response is modulated by experimental design and stimulus complexity, sometimes leading to hemodynamic responses with non-canonical shapes. We also argue that this effect is further modulated by the age of participants, the cortical regions involved, and the developmental stage of the tested cognitive process. We argue that this variability needs to be taken into account when designing and interpreting developmental studies measuring the hemodynamic response. Keywords: fNIRS, Inverted Hemodynamic Response, Experimental complexity, Infants, Developmen