Frequency identification of Wiener systems with Backlash operators using separable least squares estimators

This paper deals with the identification of Wiener models that involve backlash operators bordered by possibly noninvertible parametric lines. The latter are also allowed to cross each other making possible to account for general-shape static nonlinearities. The linear dynamic subsystem is not-necessarily parametric but is BIBO stable. A frequency identification method is developed that provides estimates of the nonlinear operator parameters as well as estimates of the linear subsystem frequency gain. The method involves standard and separable least squares estimators that all are shown to be consistent. Backlash operators and memoryless nonlinearities are handled within a unified framework.Preprin

Les corps étrangers en ORL: expérience de dix ans

Les corps étrangers (CE) représentent une pathologie fréquemment rencontrée en pratique ORL d'urgence. Ils peuvent constituer une urgence vitale par leur aspect ou leur siège. Nous présentons le bilan de dix ans sur la prise en charge des CE de la sphère ORL avec une revue de la  littérature. Il s'agit d'une étude rétrospective entre Janvier 2004 et Décembre 2013, incluant tous les cas de CE des voies aéro-digestives supérieures et auriculaires colligés dans le service d'ORL au CHU Mohammed VI de Marrakech au Maroc. Sur les 1317 cas de CE de la sphère ORL colligés durant cette période, 80,48% concernaient les enfants. Le sex-ratio était de 1,5. L'âge moyen était de 12,92 ans. Les CE oesophagiens étaient les plus fréquents (47,53%). Les complications ont été rencontrées dans 11,69% des cas. Les CE dans la sphère ORL restent fréquents en pratique quotidienne surtout chez les enfants. Leur prise en charge nécessite une intervention rapide avec un matériel adapté et des médecins entrainés. La prévention reste la meilleure solution

Retropharyngeal Abscess in Adults: Five Case Reports and Review of the Literature

Retropharyngeal abscesses are rare in adults. They occur mostly in immunocompromised patients or as a foreign body complication. We report 5 cases of retropharyngeal abscess collected in the ENT Department of CHU Mohammed VI of Marrakech, during a two-year period (December 2008 to December 2009). Local trauma by foreign body ingestion was the aetiology in four patients. The presenting symptoms, for all patients, were fever, odynophagia, torticollis, and trismus, and the clinical examination showed bulging of the posterior wall of the oropharynx. The radiography of cervical spine showed prevertebral thickening in all cases, this thickening was associated with an aspect of vertebral lysis of the fourth cervical vertebra in one case. A CT scan was performed in all our cases and showed features of retropharyngeal abscess which was associated, in one case, with spondylodiscitis. The biological assessment found one case of diabetes. The intradermal reaction to the tuberculin was clearly positive in one case. Endobuccal abscess puncture was practiced in 4 cases; only one organism was identified by culture: Staphylococcus aureus treatment was based on triple intravenous antibiotics and anti-Koch's therapy (in one case), and the surgical drainage under general anesthesia was also performed in the case of the diabetes patient which required also the correction of hyperglycemia in intensive care unit. The outcome was good in all our patients. The diagnosis of retropharyngeal abscess can be difficult and one must seek a comorbidity; a tuberculosis aetiology must be considered in countries with a high prevalence. The management of these cases is based on antibiotics and surgical drainage

Retropharyngeal Abscess in Adults: Five Case Reports and Review of the Literature

Retropharyngeal abscesses are rare in adults. They occur mostly in immunocompromised patients or as a foreign body complication. We report 5 cases of retropharyngeal abscess collected in the ENT Department of CHU Mohammed VI of Marrakech, during a two-year period (December 2008 to December 2009). Local trauma by foreign body ingestion was the aetiology in four patients. The presenting symptoms, for all patients, were fever, odynophagia, torticollis, and trismus, and the clinical examination showed bulging of the posterior wall of the oropharynx. The radiography of cervical spine showed prevertebral thickening in all cases, this thickening was associated with an aspect of vertebral lysis of the fourth cervical vertebra in one case. A CT scan was performed in all our cases and showed features of retropharyngeal abscess which was associated, in one case, with spondylodiscitis. The biological assessment found one case of diabetes. The intradermal reaction to the tuberculin was clearly positive in one case. Endobuccal abscess puncture was practiced in 4 cases; only one organism was identified by culture: Staphylococcus aureus treatment was based on triple intravenous antibiotics and anti-Koch's therapy (in one case), and the surgical drainage under general anesthesia was also performed in the case of the diabetes patient which required also the correction of hyperglycemia in intensive care unit. The outcome was good in all our patients. The diagnosis of retropharyngeal abscess can be difficult and one must seek a comorbidity; a tuberculosis aetiology must be considered in countries with a high prevalence. The management of these cases is based on antibiotics and surgical drainage

Monitoring of robot path tracking: Reconfiguration strategy design and experimental validation

International audienc

A new approach to determine the contact radius-depth curve from an indentation test in elastic-plastic and fully plastic regimes

International audienceInstrumented indentation experiments, where load and depth of penetration are measured continuously, enable an evaluation of mechanical properties such as Young's modulus, hardening exponent and yield stress. This assessment requires a precise knowledge of the true contact area between the indenter and the indented material, which depends on piling-up and sinking-in at the contact boundary. The aim of this work is to propose a new relationship between the penetration depth of a spherical indenter and the contact radius, which is valid for most metals in elastic-plastic and fully plastic regimes. Numerical simulations results of the indentation of an elastic-plastic half-space by a frictionless rigid parabolo1d of revolution show that the contact radius-indentation depth evolution can be represented by a power law. This law depends on the Young's modulus, the hardening exponent and the yield stress of the indented material. In order to use the proposed formulation for experimental spherical indentations, the model is adapted in the case of a rigid spherical indenter

Frequency identification of Wiener systems with Backlash operators using separable least squares estimators

This paper deals with the identification of Wiener models that involve backlash operators bordered by possibly noninvertible parametric lines. The latter are also allowed to cross each other making possible to account for general-shape static nonlinearities. The linear dynamic subsystem is not-necessarily parametric but is BIBO stable. A frequency identification method is developed that provides estimates of the nonlinear operator parameters as well as estimates of the linear subsystem frequency gain. The method involves standard and separable least squares estimators that all are shown to be consistent. Backlash operators and memoryless nonlinearities are handled within a unified framework