Développement d’un algorithme d’évitement de collisions pour un véhicule dans des conditions de faible adhérence

Malgré les développements technologiques considérables dans le domaine de l’assistance à la conduite, le nombre d’accidents de la route au Québec se voit augmenter de 30 % en présence de conditions hivernales, caractérisées par la présence de glace et de neige au sol, par rapport aux autres saisons. Le projet de recherche dont traite ce mémoire est réalisé dans le cadre du programme de maîtrise en génie mécanique à l’Université de Sherbrooke et vise à développer un algorithme intelligent d’évitement des collisions basé sur la physique pour un véhicule évoluant dans des conditions de faible adhérence. La stratégie proposée vise à développer une méthode de contrôle hybride entre une approche basée sur un modèle dynamique et une approche basée sur les données, pour favoriser un apprentissage rapide dans des scénarios pour lesquels la disponibilité des données est limitée. Cette approche consiste à fournir un ensemble de paramètres pertinents à la caractérisation de la relation entre le véhicule et le sol à un algorithme dont le rôle est de déterminer la manoeuvre optimale à effectuer en fonction des paramètres estimés par le filtre. Ce mémoire présente la réalisation d’une preuve de concept expérimentale d’un algorithme d’évitement de collision pour véhicules évoluant dans des conditions de faible adhérence, implémenté sur une plateforme de voiture à l’échelle 1/5ème. Un estimateur basé sur un modèle dynamique traite d’abord les données de capteurs provenant du IMU, du LIDAR et des encodeurs pour estimer les paramètres pertinents du véhicule et des conditions du sol, tels que la vitesse inertielle du véhicule v, la vitesse angulaire des roues ω, l’accélération a, le coefficient de friction μ, la cohésion c et l’angle de cisaillement interne ϕ. Ensuite, un prédicteur piloté par les données est entraîné pour prédire la manoeuvre optimale à effectuer dans la situation caractérisée par les paramètres estimés. L’expérimentation démontre qu’il est possible de produire une estimation en temps réel des paramètres du véhicule et du sol et de déterminer une manoeuvre optimale d’évitement des collisions sur la base des paramètres estimés

Using Buckingham's π\pi Theorem for Multi-System Learning Transfer: a Case-study with 3 Vehicles Sharing a Database

Learning schemes for planning and control are limited by the difficulty of collecting large amounts of experimental data or having to rely on high-fidelity simulations. This paper explores the potential of a proposed learning scheme that leverages dimensionless numbers based on Buckingham's $\pi$ theorem to improve data efficiency and facilitate knowledge sharing between similar systems. A case study using car-like robots compares traditional and dimensionless learning models on simulated and experimental data to validate the benefits of the new dimensionless learning approach. Preliminary results show that this new dimensionless approach could accelerate the learning rate and improve the accuracy of the model and should be investigated further

Technological form defects identification using discrete cosine transform method

12 pagesAbstract Manufacturers need precise tools to simulate, validate, or improve a process plan for given tolerances. Some simulation methods calculating position and orientation defect of manufactured surfaces have already been developed. A lack in these methods is the integration of form defect of surfaces. Indeed, many methods do not study manufactured surfaces, but nominal models associated to these surfaces. The method developed in this article proposes a tool describing precisely form error in order to take it into account. The work is based on a method of the literature, using discrete cosine transformation, completed by a method for identification of classical defects composing global form error and quantification of their contribution to this defect. The method is validated on simulation examples and then applied on a milled plane

OrthoInspector: comprehensive orthology analysis and visual exploration

<p>Abstract</p> <p>Background</p> <p>The accurate determination of orthology and inparalogy relationships is essential for comparative sequence analysis, functional gene annotation and evolutionary studies. Various methods have been developed based on either simple blast all-versus-all pairwise comparisons and/or time-consuming phylogenetic tree analyses.</p> <p>Results</p> <p>We have developed OrthoInspector, a new software system incorporating an original algorithm for the rapid detection of orthology and inparalogy relations between different species. In comparisons with existing methods, OrthoInspector improves detection sensitivity, with a minimal loss of specificity. In addition, several visualization tools have been developed to facilitate in-depth studies based on these predictions. The software has been used to study the orthology/in-paralogy relationships for a large set of 940,855 protein sequences from 59 different eukaryotic species.</p> <p>Conclusion</p> <p>OrthoInspector is a new software system for orthology/paralogy analysis. It is made available as an independent software suite that can be downloaded and installed for local use. Command line querying facilitates the integration of the software in high throughput processing pipelines and a graphical interface provides easy, intuitive access to results for the non-expert.</p

Experimental Investigation Of A Thermally Integrated Carnot Battery Using A Reversible Heat Pump/Organic Rankine Cycle: Influence Of System Charge On Performance Of The Reversible Scroll Compressor/Expander And Global Performance

Carnot batteries are considered a promising power-heat-power storage technology for mid- and large-scale applications. Recently, the use of dual-purpose thermal machines has been proposed in Carnot batteries. In such a system, a single unit acts as heat pump (HP, compressor operation) during charging or organic Rankine cycle (ORC, expander operation) during discharging. This configuration reduces the investment cost of the technology compared to traditional Carnot batteries using two separate machines. An experimental campaign has been performed on a small-scale (1 kWel) Carnot battery pilot plant using a single scroll compressor/expander. A wide range of operational conditions has been tested in both charging and discharging mode. The influence of the system charge on the obtainable working points in both operation modes has been discussed. It has been found that lower system charges are needed to run the system in HP-mode than in ORC-mode. At these low charges, increasing the charge in HP-mode has a positive influence on the system performance at higher source and sink temperatures. At the higher charges for ORC-mode, increasing the system charge has been found to have a positive effect on the start-up of the system in the studied operation range. Next to the qualitative discussion, the system and scroll machine has been studied quantitatively

LOWER BODY KINEMATICS AND MUSCLE ACTIVITY DURING EXERCICES IN 3D MOTORIZED ROTATING PLATFORM. IN-VIVO STUDY AND MODEL

The purpose of this study was to characterize muscle solicitations implied by the movement of a motorized rotating platform (MRP). Subjects performed five classical exercises on a MRP as part of lower limbs rehabilitation programs. EMG signals were recorded to quantify level and duration of activation of seven lower limbs muscles. Subject-specific musculoskeletal models were built and animated from kinematic recordings to estimate muscle lengths evolution. Results show that unipodal stance exercise was more demanding compared to bipodal ones. The characterization of solicitations imposed by MRP exercises could be useful for physiotherapists in order to help them to better select and configure exercises regarding to subject specificities, pathology and rehabilitation evolution

Tex19 and Sectm1 concordant molecular phylogenies support co-evolution of both eutherian-specific genes

International audienceBackground: Transposable elements (TE) have attracted much attention since they shape the genome and contribute to species evolution. Organisms have evolved mechanisms to control TE activity. Testis expressed 19 (Tex19) represses TE expression in mouse testis and placenta. In the human and mouse genomes, Tex19 and Secreted and transmembrane 1 (Sectm1) are neighbors but are not homologs. Sectm1 is involved in immunity and its molecular phylogeny is unknown. Methods: Using multiple alignments of complete protein sequences (MACS), we inferred Tex19 and Sectm1 molecular phylogenies. Protein conserved regions were identified and folds were predicted. Finally, expression patterns were studied across tissues and species using RNA-seq public data and RT-PCR. Results: We present 2 high quality alignments of 58 Tex19 and 58 Sectm1 protein sequences from 48 organisms. First, both genes are eutherian-specific, i.e., exclusively present in mammals except monotremes (platypus) and marsupials. Second, Tex19 and Sectm1 have both duplicated in Sciurognathi and Bovidae while they have remained as single copy genes in all further placental mammals. Phylogenetic concordance between both genes was significant (p-value < 0.05) and supported co-evolution and functional relationship. At the protein level, Tex19 exhibits 3 conserved regions and 4 invariant cysteines. In particular, a CXXC motif is present in the N-terminal conserved region. Sectm1 exhibits 2 invariant cysteines and an Ig-like domain. Strikingly, Tex19 C-terminal conserved region was lost in Haplorrhini primates while a Sectm1 C-terminal extra domain was acquired. Finally, we have determined that Tex19 and Sectm1 expression levels anti-correlate across the testis of several primates (ρ = −0.72) which supports anti-regulation. Conclusions: Tex19 and Sectm1 co-evolution and anti-regulated expressions support a strong functional relationship between both genes. Since Tex19 operates a control on TE and Sectm1 plays a role in immunity, Tex19 might suppress an immune response directed against cells that show TE activity in eutherian reproductive tissues

Genome-wide evidence for an essential role of the human Staf/ZNF143 transcription factor in bidirectional transcription

In the human genome, ∼10% of the genes are arranged head to head so that their transcription start sites reside within <1 kbp on opposite strands. In this configuration, a bidirectional promoter generally drives expression of the two genes. How bidirectional expression is performed from these particular promoters constitutes a puzzling question. Here, by a combination of in silico and biochemical approaches, we demonstrate that hStaf/ZNF143 is involved in controlling expression from a subset of divergent gene pairs. The binding sites for hStaf/ZNF143 (SBS) are overrepresented in bidirectional versus unidirectional promoters. Chromatin immunoprecipitation assays with a significant set of bidirectional promoters containing putative SBS revealed that 93% of them are associated with hStaf/ZNF143. Expression of dual reporter genes directed by bidirectional promoters are dependent on the SBS integrity and requires hStaf/ZNF143. Furthermore, in some cases, functional SBS are located in bidirectional promoters of gene pairs encoding a noncoding RNA and a protein gene. Remarkably, hStaf/ZNF143 per se exhibits an inherently bidirectional transcription activity, and together our data provide the demonstration that hStaf/ZNF143 is indeed a transcription factor controlling the expression of divergent protein–protein and protein–non-coding RNA gene pairs

Detecting the molecular scars of evolution in the Mycobacterium tuberculosis complex by analyzing interrupted coding sequences

<p>Abstract</p> <p>Background</p> <p>Computer-assisted analyses have shown that all bacterial genomes contain a small percentage of open reading frames with a frameshift or in-frame stop codon We report here a comparative analysis of these interrupted coding sequences (ICDSs) in six isolates of <it>M. tuberculosis</it>, two of <it>M. bovis </it>and one of <it>M. africanum </it>and question their phenotypic impact and evolutionary significance.</p> <p>Results</p> <p>ICDSs were classified as "common to all strains" or "strain-specific". Common ICDSs are believed to result from mutations acquired before the divergence of the species, whereas strain-specific ICDSs were acquired after this divergence. Comparative analyses of these ICDSs therefore define the molecular signature of a particular strain, phylogenetic lineage or species, which may be useful for inferring phenotypic traits such as virulence and molecular relationships. For instance, <it>in silico </it>analysis of the W-Beijing lineage of <it>M. tuberculosis</it>, an emergent family involved in several outbreaks, is readily distinguishable from other phyla by its smaller number of common ICDSs, including at least one known to be associated with virulence. Our observation was confirmed through the sequencing analysis of ICDSs in a panel of 21 clinical <it>M. tuberculosis </it>strains. This analysis further illustrates the divergence of the W-Beijing lineage from other phyla in terms of the number of full-length ORFs not containing a frameshift. We further show that ICDS formation is not associated with the presence of a mutated promoter, and suggest that promoter extinction is not the main cause of pseudogene formation.</p> <p>Conclusion</p> <p>The correlation between ICDSs, function and phenotypes could have important evolutionary implications. This study provides population geneticists with a list of targets, which could undergo selective pressure and thus alters relationships between the various lineages of <it>M. tuberculosis </it>strains and their host. This approach could be applied to any closely related bacterial strains or species for which several genome sequences are available.</p

ICDS database: interrupted CoDing sequences in prokaryotic genomes

Unrecognized frameshifts, in-frame stop codons and sequencing errors lead to Interrupted CoDing Sequence (ICDS) that can seriously affect all subsequent steps of functional characterization, from in silico analysis to high-throughput proteomic projects. Here, we describe the Interrupted CoDing Sequence database containing ICDS detected by a similarity-based approach in 80 complete prokaryotic genomes. ICDS can be retrieved by species browsing or similarity searches via a web interface (). The definition of each interrupted gene is provided as well as the ICDS genomic localization with the surrounding sequence. Furthermore, to facilitate the experimental characterization of ICDS, we propose optimized primers for re-sequencing purposes. The database will be regularly updated with additional data from ongoing sequenced genomes. Our strategy has been validated by three independent tests: (i) ICDS prediction on a benchmark of artificially created frameshifts, (ii) comparison of predicted ICDS and results obtained from the comparison of the two genomic sequences of Bacillus licheniformis strain ATCC 14580 and (iii) re-sequencing of 25 predicted ICDS of the recently sequenced genome of Mycobacterium smegmatis. This allows us to estimate the specificity and sensitivity (95 and 82%, respectively) of our program and the efficiency of primer determination