Electronic Simulation and Hardware Implementation of Two Coupled Periodically Forced Duffing and Van der Pol oscillators and its Application to Secure Communication

Confirmation of the existence of complex behavior and synchronization of non-identical chaotic systems as reported in literature attracts much interest in secure communication, but practical implementation is still challenging. In this work, the dynamics of coupled non-identical circuits comprising periodically forced Duffing and Van der Pol oscillators is investigated via electronic simulation using Multism software and hardware implementation on electronic circuits board. After complete synchronization is achieved between the Duffing (Transmitter) and Van der Pol (receiver) circuits through the variation of the coupling resistor of the controller, its application to secure communication is therefore demonstrated experimentally and via multism. The results from the electronic simulation and hardware implementation on bread board using analog components are in good agreement with the numerical results in literature

Generalized Adaptive Backstepping Synchronization for Non-Identical Parametrically Excited Systems

In this paper, we investigate the synchronization of chaotic systems consisting of non-identical parametrically excited oscillators. The backstepping design, which is a recursive procedure that combines the choice of a Lyapunov function with the design of a controller is generalized and employed so as to achieve global chaos synchronization between a parametrically excited gyroscope and each of the parametrically excited pendulum and Duffing oscillator. Numerical simulations are implemented to verify the results

Metastase cervicale d’un adenome pleomorphe

Introduction : L’adénome pléomorphe est la tumeur la plus fréquente des glandes salivaires. Malgré son caractère bénin, de rares cas de métastases à distance ont été rapportés, touchant plus fréquemment l’os, les poumons et les ganglions lymphatiques. La localisation sous-cutanée, que nous rapportons dans ce travail, est exceptionnelle.Observation : Il s’agit d’une patiente de 41 ans, qui a eu une parotidectomie exofaciale gauche, par voie de lifting, pour un adénome pléomorphe, et qui a consulté, neuf ans plus tard, pour un nodule sous-cutané cervical moyen gauche. Une exérèse sous anesthésie locale a été réalisée. L’examen histologique de la pièce d’exérèse a conclu à une localisation secondaire d’un adénome pléomorphe. Aucune récidive locale ni à distance n’a été détectée, après trois ans de recul.Conclusion : L’adénome pléomorphe métastasant (APM), décrit depuis 1953, est rare. Aucune particularité clinique ni histologique ne permet de distinguer les formes métastatiques des formes classiques non métastatiques. Le mécanisme exact des métastases reste incertain mais semble être lié à une dissémination intra-vasculaire de cellules tumorales, lors de la manipulation chirurgicale de la tumeur primitive ou des récidives. Si la métastase est accessible, le pronostic est excellent après une exérèse complète.Mots-clés : adénome pléomorphe, métastase, peau, couIntroduction : Pleomorphic adenoma is the most common salivary tumor. Although clinically and histologically known as a benign tumor, there are rare reports of metastasis to distant sites, most commonly in bone, lungs, and lymph nodes. The subcutaneous site,reported in this case, is exceptional.Case-report : A 41 year-old patient, with history of left exofacial parotidectomy with a lifting incision, consulted after nine years for a left cervical subcutaneous nodule. An excision was performed under local anesthesia. The histological exam concluded in a secondary localization of pleomorphic adenoma. No local or distant recurrence was detected after three years.Conclusion : Metastasic pleomorphic adenoma, described since 1953, is uncommon. There are no known clinical or histological features that distinguish metastatic from non metastatic forms. The metastasis mechanism is uncertain, but seems to be related to vascular dissemination of tumoral cells, while surgical manipulation of the primary tumor or the recurrences. If metastasis is accessible, the prognosis is excellent after a complete excision.Keywords : pleomorphic adenoma, metastasis, skin, neck

Bifurcation and Chaos in Coupled Ratchets exhibiting Synchronized Dynamics

The bifurcation and chaotic behaviour of unidirectionally coupled deterministic ratchets is studied as a function of the driving force amplitude ($a$) and frequency ($\omega$). A classification of the various types of bifurcations likely to be encountered in this system was done by examining the stability of the steady state in linear response as well as constructing a two-parameter phase diagram in the ($a -\omega$) plane. Numerical explorations revealed varieties of bifurcation sequences including quasiperiodic route to chaos. Besides, the familiar period-doubling and crises route to chaos exhibited by the one-dimensional ratchet were also found. In addition, the coupled ratchets display symmetry-breaking, saddle-nodes and bubbles of bifurcations. Chaotic behaviour is characterized by using the sensitivity to initial condition as well as the Lyapunov exponent spectrum; while a perusal of the phase space projected in the Poincar$\acute{e}$ cross-section confirms some of the striking features.Comment: 7 pages; 8 figure

Une etiologie rare d’une ulceration palatine : la sialometaplasie necrosante

La sialométaplasie nécrosante (SN) est une affection salivaire bénigne et rare, touchant principalement les glandes salivaires palatines et présentant des ressemblances cliniques et histologiques avec les carcinomes orales. Nous rapportons un cas de SN chez une patiente de 73 ans, non tarée, édentée, qui rapporte la notion de prothèse ancienne mal adaptée et qui présente une lésion ulcéro-végétante, bien limitée, douloureuse, palatine gauche, évoluant depuis 3 mois. Le scanner du massif facial a montré un épaississement des parties molles palatines avec un aspect aminci et irrégulier de l’os en regard. Une pathologie maligne à type de carcinome muco-épidermoide a été évoquée. Une exérèse radicale de la lésion a été réalisée et l’examen histologique a conclu à une SN.Mots clés : Sialométaplasie nécrosante; orale; palais; histologieNecrotizing sialometaplasia (NS) is a relatively uncommon benign disease of the salivary glands that most commonly occurs in the palate. It is often confused clinically and histopathologically with malignancies, such as squamous cell carcinoma or mucoepidermoid carcinoma. We report a case of NS in an edentate 73-year-old woman, with no medical history, showed up with a painful, well limited ulcerative lesion on the left palate, reporting its appearance three months ago. Reported also that she had a badly adapted removable denture. CT scan showed a thickening of the palate’s soft tissues with bone irregularity and thinning. A mucoepidermoid carcinoma was suspected. The patient underwent a radical excision of the lesion and histopathological diagnosis of NS was made.Keywords: Necrotizing sialometaplasia; oral; palate; histolog

Computer and Hardware Modeling of Periodically Forced

Numerical simulation results for the dynamics o

Hyperchaos and bifurcations in a driven Van der Pol–Duffing oscillator circuit

We investigate the dynamics of a driven Van der Pol–Duffing oscillator circuit and show the existence of higher-dimensional chaotic orbits (or hyperchaos), transient chaos, strange-nonchaotic attractors, as well as quasiperiodic orbits born from Hopf bifurcating orbits. By computing all the Lyapunov exponent spectra, scanning a wide range of the driving frequency and driving amplitude parameter space, we explore in two-parameter space the regimes of different dynamical behaviours

Phase synchronization of coupled hyper-chaotic duffing oscillator

No AbstractJournal of the Nigerian Association of Mathematical Physics Vol. 8 2004: pp. 203-21