Aeromechanical stability of a hingeless rotor in hover and forward flight: Analysis and wind tunnel tests

A research effort of analysis and testing was conducted to investigate the ground resonance phenomenon of a soft in-plane hingeless rotor. Experimental data were obtained using a 9 ft. (2.74 m) diameter model rotor in hover and forward flight. Eight model rotor configurations were investigated. Configuration parameters included pitch flap coupling, blade sweep and droop, and precone of the blade feathering axis. An analysis based on a comprehensive analytical model of rotorcraft aerodynamics and dynamics was used. The moving block was used to experimentally determine the regressing lead lag mode damping. Good agreement was obtained between the analysis and test. Both analysis and experiment indicated ground resonance instability in hover. An outline of the analysis, a description of the experimental model and procedures, and comparison of the analytical and experimental data are presented

An experimental investigation of the aeromechanical stability of a hingeless rotor in hover and forward flight

Analysis and testing were conducted in the Langley Transonic Dynamics Tunnel to investigate the aeromechanical stability of a soft inplane hingeless rotor model. Rotor stability data were obtained in hover and in forward flight up to an advance ratio of 0.35. Model rotor parameters evaluated were blade sweep and droop, pre-cone of the blade feathering axis, and blade pitch-flap coupling. Data obtained during these tests are presented without analysis

Aeroelastic model helicopter rotor testing in the Langley TDT

Wind-tunnel testing of a properly scaled aeroelastic model helicopter rotor is considered a necessary phase in the design development of new or existing rotor systems. For this reason, extensive testing of aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the NASA Langley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the use of Freon as a test medium. A description of the TDT and a discussion of the benefits of using Freon as a test medium are presented. A description of the model test bed used, the Aeroelastic Rotor Experimental System (ARES), is also provided and examples of recent rotor tests are cited to illustrate the advantages and capabilities of aeroelastic model rotor testing in the TDT. The importance of proper dynamic scaling in identifying and solving rotorcraft aeroelastic problems, and the importance of aeroelastic testing of model rotor systems in the design of advanced rotor systems are demonstrated

Magnetisation studies in Co-Tb / Pt multilayers

We have studied the magnetization in Co86Tb14/Pt multilayers under fields up to 1.8 T and as at room temperature. As the do-Tb layer thickness (tCoTb) decreases below 200 Å the saturation magnetization magnetization (M) increases, the rectangularity of the M-H loops and the coercivity (Hc ) decrease. The effective anisotropy Keff of the multilayers was determined by a torque magnetometer. The product Keff×tCoTb shows a linear dependence with tCoTb as normally found for the superlatices yielding the bulk and surface anisotropies of 106 erg/cm3 and –0.2 erg/cm2 , respectively. These results are explained in terms of an interfacial Co-Pt layer. Keff and Hc are related by the equation Hc = α Keffn/M with the fitting parameters α and n.We have studied the magnetization in Co86Tb14/Pt multilayers under fields up to 1.8 T and as at room temperature. As the do-Tb layer thickness (tCoTb) decreases below 200 Å the saturation magnetization magnetization (M) increases, the rectangularity of the M-H loops and the coercivity (Hc ) decrease. The effective anisotropy Keff of the multilayers was determined by a torque magnetometer. The product Keff×tCoTb shows a linear dependence with tCoTb as normally found for the superlatices yielding the bulk and surface anisotropies of 106 erg/cm3 and –0.2 erg/cm2 , respectively. These results are explained in terms of an interfacial Co-Pt layer. Keff and Hc are related by the equation Hc = α Keffn/M with the fitting parameters α and n

A Hybrid Approach for Counting Templates in Images

© 2020 ACM. In the research, hybrid algorithm for counting repeated objects in the image is proposed. Proposed algorithm consists of two parts. Template matching sub-algorithm is based on normalized cross correlation function which is widely used in image processing application. Template matching can be used to recognize and/or locate specific objects in an image. Neural network sub-algorithm is needed to filter out false positives that may occur during cross correlation function evaluation. In the last section of the paper experimental evaluation is carried out to estimate the performance of the proposed template matching algorithm for images of blood microscopy and chamomile field image. In the first case, the task is to count erythrocytes in the blood sample. In the second case, it is needed to count the flowers in the field. For all 2 datasets we got precise results that coincides with actual number of objects in image. The reason of such performance is that convolutional neural network sub-algorithm improved initial results of template-matching sub-algorithm based on correlation function

Les tumeurs parotidiennes

Objectif : Les tumeurs des glandes salivaires sont rares, dominées en fréquence par les tumeurs parotidiennes. elles sont caractérisées par une grande hétérogénéité morpho-histologique. Les formes bénignes sont les plus fréquentes dominées par l’adénome pléomorphe. Le traitement de ces tumeurs demeure chirurgical en premier lieu.Matériel et méthodes: Cette étude est rétrospective portant sur 47 cas de tumeurs parotidiennes sur une période de 10 ans (janvier 2000 à décembre 2009). L’étude des dossiers nous a permis de relever toutes les données cliniques et thérapeutiques. Notre recul est de deux ans.Résultats : L’âge moyen de nos patients était de 42 ans avec un sex-ratio de 2,58. Les tumeurs bénignes représentaient 89 % et 11 % étaient malignes. L’adénome pléomorphe était la tumeur bénigne la plus fréquente. La tumeur maligne la plus commune était le carcinome muco-épidermoïde. Le traitement de choix est la parotidectomie partielle ou totale. Cependant, la paralysie du nerf facial reste la complication principale de la chirurgie parotidienne.Conclusion : Les formes bénignes sont prédominante s, dont le plus fréquent demeure l’adénome pléomorphe. L’imagerie moderne permet une approche histopathologique de nature. Le traitement de choix est la parotidectomie totale ou partielle. La radiothérapie peut être indiquée dans les formes malignes.Mots-clés : Tumeur, Parotide, Adénome pléomorphe, Maligne, Chirurgie

Fasciite nodulaire de la cavite buccale

Introduction: Nodular fasciitis is a benign tumour-like lesion characterized by fibroblastic proliferation. It is common in subcutaneous fascia, usually of the upper extremity but it's very rare in the oral cavity. Frequently misdiagnosed as sarcoma due to its rapid growth, rich cellularity and mitotic activity.Patients and Methods: One patient with an oral nodular fasciitis and a review of literature are reported in order to describe the diagnostic and therapeutic management of this tumour.Case presentation: A 50-year-old female with an intraorally swelling that had been growing progressively over one month. There was no history of trauma. Clinical examination revealed a firm mass palpable measuring approximately 4 cm in diameter. She had an excisional biopsy under local anaesthetic with histopathological analysis. The lesion was surgicalremoved under general anaesthesia through an intraoral approach. One year after excision of the tumour, the oral cavity was free of tumour.Conclusion: Nodular fasciitis is an entity characterized by rapid growth, rich cellularity and mitotic activity, although it is not malignant. It can only be diagnosed by histopathological examination of a biopsy with immunohistochemical staining.The treatment of choice is the complete surgical excision.Keywords: Nodular fasciitis, Oral cavity, Surgical treatment

Les cancers de l’orbite etude retrospective à propos de 31 cas

locorégionale rendant le traitement difficile et mutilant. Dans ce travail, nous rapportons notre expérience dans la prise en charge diagnostique et thérapeutique de ces tumeurs. Matériels et méthodes : Notre étude rétrospective a concerné 31 cas de cancers de l’orbite colligés sur 13 ans (1993- 2005). Tous les patients ont bénéficié d’un examen clinique complet, d’une imagerie du massif facial (TDM et/ou IRM) et d’une biopsie de la tumeur. Le traitement a été basé sur la chirurgie, la radiothérapie et/ou la chimiothérapie. Résultats : La symptomatologie clinique était dominée par les signes ophtalmologiques et les algies faciales. L’imagerie a montré dans tous les cas un processus expansif tissulaire à point de départ orbitaire, avec lyse osseuse orbitaire chez 16 patients (51,6%), une extension au massif facial chez 7 patients (22,6%), endocrâniennes chez 6 patients (19,4%) et des formes bilatérales atteignant les deux orbites dans 3 cas (9,7%) l’anatomopathologie montrait une prédominance des lymphomes malins non hodgkiniens (32,3%) et des carcinomes épidermoïdes (32,3%), suivis des rhabdomyosarcomes embryonnaires (19,4 %). Douze patients ont été traités par chirurgie et radiothérapie postopératoire, dix patients par une association radio-chimiothérapie, et neuf autres par une chimiothérapie néo-adjuvante. La survie globale était de 67,8% à 3 ans, 48,4% à 5 ans et 22,6% à 10 ans. Conclusion : Les cancers de l’orbite sont de mauvais pronostic. Un diagnostic précoce et un traitement radical et adapté au type histologique permet d’améliorer la survie et la qualité de vie chez les patients atteints de ces tumeurs.Mots-clés : Orbite, cancer, lymphome, carcinome épidermoïde, rhabdomyosarcom