Modeling of Time-Varying (max,+) Systems by means of Weighted Timed Event Graphs

International audienceThe (max,+) theory allows to describe the behavior of Timed Event Graphs (TEG) with constant holding times. For time-varying systems, a class of First-In First-Out TEGs with periodic holding times has already been studied in the literature. We show here that such time-varying TEGs can be modeled by equivalent Weighted TEGs for which an input-output model exists. In summary, we can describe FIFO TEGs with periodic holding times by means of ultimately periodic formal series in a dioid denoted E * per δ

Visibility Contractors: Application to Mobile Robot Localization

Visibility is studied and used in several fields: computer graphics, telecommunication, robotics... For instance, in Computer-aided design (CAD) synthesis images are created by simulating light propagation in a scene. Visibility notions are then necessary to compute the visible objects from a point of view, and the shadow of those objects. In mobile robotics the visibility is used for path planning (visibility graph) and localization problems. This presentation is about visibility information for mobile robot localization. The objective is twofold. First a visibility notion based on segment intersections is presented. By considering a set-membership approach it is possible to develop contractors associated to this visibility relation. Then two applications of those visibility contractors to mobile robot localization are presented. The first one corresponds to the pose tracking of a team of robots. The idea is to use a Boolean information (the visibility between two robots: two robots are visible or not) in order to avoid the drifting of those robots (in order to maintain the precision of their position estimations). The second application corresponds to the processing of an original constraint for a set-membership global localization algorithm. This global localization algorithm is based on a CSP approach (Constraint Satisfaction Problem). Adding a visibility constraint to this CSP improves the accuracy of the algorithm

Optimal Control of a Class of Timed Discrete Event Systems with Shared Resources, An Approach Based on the Hadamard Product of Series in Dioids

The topic of this paper is modeling and control of timed discrete event systems in a dioid framework if systems operate under the restriction of shared resources. The behavior of such systems can be elegantly modeled using the Hadamard product of series in dioids. Using residuation of the Hadamard product, it is possible to compute optimal control, where optimality is in the sense of a lexicographical order reflecting the chosen prioritization of subsystems. The paper concludes with an example, illustrating the efficiency of the proposed method

Morphometric variations at an ecological scale: Seasonal and local variations in feral and commensal house mice

The time scales of evolutionary and ecological studies tend to converge, as evidenced by studies that have shown contemporary evolution can occur as fast as ecological processes. This opens new questions regarding variation of characters usually considered to change mostly along an evolutionary time scale, such as morphometric traits, including osteological and dental features such as mandibles and teeth of mammals. Using two-dimensional geometric morphometric approach, we questioned whether such features can change on a seasonal and local basis, in relation to the ecological dynamics of the populations. Our model comprised populations of house mice (Mus musculus domesticus) in two contrasted situations in mainland Western Europe: a feral population vs. two close commensal populations. Mitochondrial DNA (D-loop) provided insight into the diversity and dynamics of the populations. The feral population appeared as genetically highly diversified, suggesting a possible functioning as a sink in relation to the surrounding commensal populations. In contrast, commensal populations were highly homogeneous from a genetic point of view, suggesting each population to be isolated. This triggered morphological differentiation between neighboring farms. Seasonal differences in morphometric traits (mandible size and shape and molar size and shape) were significant in both settings, although seasonal variations were greater in the feral than in the commensal population. Seasonal variations in molar size and shape could be attributed to differential wear in young or overwintered populations. Differences in mandible shape could be related to aging in overwintered animals, but also possibly to differing growth conditions depending on the season. The impact of these ecological processes on morphometric traits is moderate compared to divergence over a large biogeographic scale, but their significance nevertheless underlines that even morphological characters may trace populations dynamics at small scale in time and space

Model-based approach for fault diagnosis using set-membership formulation

This paper describes a robust model-based fault diagnosis approach that enables to enhance the sensitivity analysis of the residuals. A residual is a fault indicator generated from an analytical redundancy relation which is derived from the structural and causal properties of the signed bond graph model. The proposed approach is implemented in two stages. The first stage consists in computing the residuals using available input and measurements while the second level leads to moving horizon residuals enclosures according to an interval consistency technique. These enclosures are determined by solving a constraint satisfaction problem which requires to know the derivatives of measured outputs as well as their boundaries. A numerical differentiator is then proposed to estimate these derivatives while providing their intervals. Finally, an inclusion test is performed in order to detect a fault upon occurrence. The proposed approach is well suited to deal with different kinds of faults and its performances are demonstrated through experimental data of an omni-directional robot

Interval Analysis for Kidnapping Problem using Range Sensors

This paper presents a new method to deal with thekidnapping problem of mobile robots. By using a range sensor and a discrete map of the indoor environment, the robot has to determine its pose (position and orientation). The idea is to obtain the smallest set of feasible poses compatible with the mesurements and the map. This method is a set membership approach based on interval analysis and constraint propagation, which allows to get results in a guaranteed way

The challenge of measuring quality of life in children with Hirschsprung's disease or anorectal malformation

PURPOSE: The aim of the present study was to assess, after adaptation to French, the only specific quality of life (QoL) instrument for children with Hirschsprung\u27s disease or anorectal malformation, the Hirschsprung\u27s disease/Anorectal Malformation Quality of Life questionnaire (HAQL), in order to get a standardized QoL evaluation instrument that could further be used to help health care improvement. METHODS: The study was conducted in three teaching hospitals, including the French reference center for anorectal and pelvic malformations. After adaptation to French, QoL questionnaires were sent to the children and proxies. The questionnaire was mailed to 280 families. Psychometrics properties of the questionnaires (validity and reliability) were analysed from 120 proxy and 96 child questionnaires. RESULTS: The HAQL with the original structure was not acceptable. Exploratory steps led to a clinically pertinent structure that had acceptable fit and good validity and reliability properties. The final structure pools physical symptoms (continence, discomfort) and psychosocial dimensions (general well-being, social and emotional functioning) of QoL. CONCLUSION: The final structure, despite the disadvantage of being a new structure, allows assessment of QoL in this population and has the advantage of being shorter and validated on the clinical postoperative questionnaire from the Krickenbeck international consensus

The complete mitochondrial genome of a parasite at the animal-fungal boundary

Background: Sphaerothecum destruens is an obligate intracellular fish parasite which has been identified as a serious threat to freshwater fishes. Taxonomically, S. destruens belongs to the order Dermocystida within the class Ichthyosporea (formerly referred to as Mesomycetozoea), which sits at the animal-fungal boundary. Mitochondrial DNA (mtDNA) sequences can be valuable genetic markers for species detection and are increasingly used in environmental DNA (eDNA) based species detection. Furthermore, mtDNA sequences can be used in epidemiological studies by informing detection, strain identification and geographical spread. Methods: We amplified the entire mitochondrial (mt) genome of S. destruens in two overlapping long fragments using primers designed based on the cox1, cob and nad5 partial sequences. The mt-genome architecture of S. destruens was then compared to close relatives to gain insights into its evolution. Results: The complete mt-genome of Sphaerothecum destruens is 23,939 bp in length and consists of 47 genes including 21 protein-coding genes, 2 rRNA, 22 tRNA and two unidentified open reading frames. The mitochondrial genome of S. destruens is intronless and compact with a few intergenic regions and includes genes that are often missing from animal and fungal mt-genomes, such as, the four ribosomal proteins (small subunit rps13 and 14; large subunit rpl2 and 16), tatC (twin-arginine translocase component C), and ccmC and ccmF cytochrome c maturation protein ccmC and heme lyase). Conclusions: We present the first mt-genome of S. destruens which also represents the first mt-genome for the order Dermocystida. The availability of the mt-genome can assist the detection of S. destruens and closely related parasites in eukaryotic diversity surveys using eDNA and assist epidemiological studies by improving molecular detection and tracking the parasite’s spread. Furthermore, as the only representative of the order Dermocystida, its mt-genome can be used in the study of mitochondrial evolution of the unicellular relatives of animals

A simple theory of molecular organization in fullerene containing liquid crystals

Systematic efforts to synthesise fullerene containing LCs have produced a variety of successful model compounds. We present a simple molecular theory relating the self-organisation observed in these systems to their molecular structure. The interactions are modelled by dividing each molecule into a number of sub-molecular blocks to which specific interactions are assigned. Three types of blocks are introduced, corresponding to fullerene units, mesogenic units, and non-mesogenic linkage units. The blocks are constrained to move on a rectangular 3-dimensional lattice and molecular flexibility is allowed by retaining a number of representative conformations within the block representation of the molecule. Calculations are presented for a variety of molecular architectures including twin mesogenic branch mono-adducts of C60, twin dendro-mesogenic branch mono-adducts and conical (badminton shuttlecock) multi-adducts of C60. In spite of its many simplifications, the theory accounts remarkably well for the phase behaviour of these systems.Comment: 22 pages, 9 figure