Mastiodite masquee: a propos de deux observations

La mastoïdite masquée (MM) se définit comme un état inflammatoire latent de la muqueuse et de l’os mastoïdien avec un tympan normal. Elle est révélée par une complication généralement endocrânienne. Le traitement est une mastoïdectomie associée à une antibiothérapie intraveineuse. Nous rapportons deux observations de mastoïdites masquées dont le diagnostic a été évoqué par l’examen tomodensitométrique qui a rattaché les complications endocrâniennes à leur origine mastoïdienne. Le but de notre travail est de discuter les circonstances diagnostiques, les investigations paracliniques et le traitement des mastoïdites masquées.Mots-clés : mastoïdite masquée, complications endocrâniennes, mastoïdectomie

Radionescrose cerebrale a propos d\'une observation

No Abstract. Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 17 2006: pp. 55-5

Thrombophlebite du sinus caverneux d’origine otogene : a propos d’un cas

But : Nous illustrons un cas de thrombophlébite du sinus caverneux compliquant une oto-mastoïdite. Nous étudions à la lumière de la littérature les difficultés diagnostiques et l’importance de la mise en oeuvre d’un traitement précoce et adapté afin d’éviter les séquelles ultérieures. Observation : Il s’agit d’un enfant âgé de 14 ans, qui avait présenté une exophtalmie avec oedème palpébral bilatéral et une baisse de l’acuité visuelle d’aggravation progressive au décours d’un épisode otitique. L’examen avait objectivé une paralysie faciale périphérique droite et à l’otoscopie un tympan droit bombé congestif.La TDM avait mis en évidence une thrombophlébite du sinus caverneux associée à un abcès cérébral et à un abcès rétropharyngé avec une oto-mastoïdite homolatérale. Le malade a été traité par une antibiothérapie à large spectre associée à une héparinothérapie, avec mastoïdectomie droite et drainage de l’abcès rétro-pharyngé. L’évolution a été marquée par la régression totale de la paralysie faciale, avec reperméabilisation du sinus caverneux et disparition totale de l’abcès temporal au contrôle scannographique. Le patient a gardé comme seule séquelle une cécité mono oculaire gauche. Conclusion : La thrombophlébite du sinus caverneux est une affection rare, surtout dans son origine otogène elle doit être diagnostiquée et traitée le plutôt possible, afin de prévenir les séquelles ou d’obtenir la régression de ces dernières. Le traitement doit associer une antibiothérapie à large spectre, les anticoagulants et un drainage chirurgical approprié du foyer septique.Mots-clés : Thrombophlébite du sinus caverneux, Otite moyenne aiguë, complication

Numerical investigation of plastic flow and residual stresses generated in hydroformed tubes

During tube hydroforming process, the friction conditions between the tube and the die have a great importance on the material plastic flow and the distribution of residual stresses of the final component. Indeed, a three-dimensional finite element model of a tube hydroforming process in the case of square section die has been performed, using dynamic and static approaches, to study the effect of the friction conditions on both plastic flow and residual stresses induced by the process. First, a comparative study between numerical and experimental results has been carried out to validate the finite element model. After that, various coefficients of friction were considered to study their effect on the thinning phenomenon and the residual stresses distribution. Different points have been retained from this study. The thinning is located in the transition zone cited between the straight wall and the corner zones of hydroformed tube due to the die–tube contact conditions changes during the process. In addition, it is clear that both die–tube friction conditions and the tube bending effects, which occurs respectively in the tube straight wall and corner zones, are the principal causes of the obtained residual stresses distribution along the tube cross-section

Maladie de castleman multicentrique: A propos d’un cas

La maladie de Castleman est une affection rare, d’étiologie inconnue, caractérisée sur le plan histologique par une hyperplasie lymphoïde angiofolliculaire. Elle se présente sous deux formes différentes, localisée et multicentrique. Nous rapportons une observation de maladie de Castleman chez un homme de 69 ans qui avait consulté pour des adénopathies cervicales chroniques. Il s’agissait d’une forme multicentrique d’évolution rapidement fatale malgré un traitement agressif associant corticothérapie et chimiothérapie.Mots clès : Hyperplasie lymphoïde angio-folliculaire, adénopathie cervicale, maladie de Castleman, lymphome

Design and analysis of vibration energy harvesters based on peak response statistics

Energy harvesting using cantilever piezoelectric vibration energy harvesters excited by Gaussian broadband random base excitation is considered. The optimal design and analysis of energy harvesters under random excitation is normally performed using the mean and standard deviation of a response quantity of interest, such as the voltage. An alternative approach based on the statistics of the peak voltage is developed in this paper. Three extreme response characteristics, namely (a) level crossing, (b) response peaks above certain level, and (c) fractional time spend above a certain level, have been employed. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions have been derived for number of level crossings, statistics of response peaks and fractional time spend above a certain level for the output voltage. It is shown that these quantities can be related to the standard deviation of the voltage and its derivative with respect to time. Direct numerical simulation has been used to validate the analytical expressions. Based on the analytical results, closed-form expressions for optimal system parameters have been proposed. Numerical examples are given to illustrate the applicability of the analytical results

Electromechanical analysis of an adaptive piezoelectric energy harvester controlled by two segmented electrodes with shunt circuit networks

This paper presents an adaptive power harvester using a shunted piezoelectric control system with segmented electrodes. This technique has spurred new capability for widening the three simultaneous resonance frequency peaks using only a single piezoelectric laminated beam where normally previous works only provide a single peak for the resonance at the first mode. The benefit of the proposed techniques is that it provides effective and robust broadband power generation for application in self-powered wireless sensor devices. The smart structure beam with proof mass offset is considered to have simultaneous combination between vibration-based power harvesting and shunt circuit control-based electrode segments. As a result, the system spurs new development of the two mathematical methods using electromechanical closed-boundary value techniques and Ritz method-based weak-form analytical approach. The two methods have been used for comparison giving accurate results. For different electrode lengths using certain parametric tuning and harvesting circuit systems, the technique enables the prediction of the power harvesting that can be further proved to identify the performance of the system using the effect of varying circuit parameters so as to visualize the frequency and time waveform responses

Design, analysis, and feedback control of a nonlinear micro-piezoelectric–electrostatic energy harvester

A nonlinear micro-piezoelectric–electrostatic energy harvester is designed and studied using mathematical and computational methods. The system consists of a cantilever beam substrate, a bimorph piezoelectric transducer, a pair of tuning parallel-plate capacitors, and a tip–mass. The governing nonlinear mathematical model of the electro-mechanical system including nonlinear material and quadratic air-damping is derived for the series connection of the piezoelectric layers. The static and modal frequency curves are computed to optimize the operating point, and a parametric study is performed using numerical methods. A bias DC voltage is used to adapt the system to resonate with respect to the frequency of external vibration. Furthermore, to improve the bandwidth and performance of the harvester (and achieve a high level of harvested power without sacrificing the bandwidth), a nonlinear feedback loop is integrated into the design