30 research outputs found
Preparation, characterization and thermal stability of poly[2-(Dimethylamino)ethyl acrylate]
No full textAn axisymmetric cubic finite element for laminated anisotropic cylindrical shells
No full textA new cubic finite element model which can be used for the analysis of thin or moderately thick laminated composite circular cylindrical shells is developed. This model accounts for transverse shear deformation and rotary inertia effects. Unlike conventional shell elements, this new element allows separate rotational degrees of freedom for each layer (hence giving more flexibility than models based on classical lamination theory) but does not require translational degrees of freedom beyond those necessary for a single layer. Continuity of displacements between layers is assumed but not continuity of the traction vectors.In problems where different layers may have to be modeled separately, this element offers an efficient alternative to three-dimensional (solid) elements where many elements would have to be used in the model in order to keep the aspect ratio within acceptable range, or to two-dimensional laminated elements in which in-plane degrees of freedom are not condensed out. The new element shows no evidence of shear locking, at least for radius to thickness ratios up to 200. Hence, reduced/selective numerical integration schemes may not be needed.Numerical results predicted by the new model compare well with results from elasticity, classical lamination theory, and constant shear-angle theory solutions of some sample problems.Made available in DSpace on 2011-05-07T13:09:36Z (GMT). No. of bitstreams: 2
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Moringa Oleifera Extract as Green Corrosion Inhibitor for Zinc in Polluted Sodium Chloride Solutions *Corresponding Author
No full textIn this work, moringa extract was examined as a green corrosion inhibitor for zinc in 3.5 % NaCl and 16 ppm solution by using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Results obtained showed that this extract of moringa offered good protection against corrosion of zinc metal and exhibited high inhibition efficiencies. The inhibition efficiency was found to increase with increase in the extract concentration. The adsorption of the inhibitor molecules on the zinc metal surface follows Temkin adsorption isotherm and behaves as mixed type inhibitor
Thermal stability of poly(2‐acrylamido‐2‐methylpropanesulphonic acid) and polymer complexes of 2‐acrylamido‐2‐methylpropanesulphonic acid with some transition metal salts
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Recycling of vulcanized waste rubber through halogenations and amination chemical reactions
No full textAnalysis of n-Si(111) during photocurrent oscillations in Fluoridic solutions
No full textThe surface condition of n-Si(111) exposed to an acidic fluoride solution under white light illumination is strongly influenced by the applied electrode potential. Photocurrent oscillations at n-Si(111) are investigated in-situ by ellipsometry and Fourier-transform infrared spectroscopy (FTIR). In-situ ellipsometric data show that the current oscillation is concomitant with the fluctuation of the optical parameters D and Y. The FTIR investigations revelate that the Si-O signal has a self-oscillating mode and varies by more than ± 20% what explains the fluctuation in D and Y.The surface condition of n-Si(111) exposed to an acidic fluoride solution under white light illumination is strongly influenced by the applied electrode potential. Photocurrent oscillations at n-Si(111) are investigated in-situ by ellipsometry and Fourier-transform infrared spectroscopy (FTIR). In-situ ellipsometric data show that the current oscillation is concomitant with the fluctuation of the optical parameters D and Y. The FTIR investigations revelate that the Si-O signal has a self-oscillating mode and varies by more than ± 20% what explains the fluctuation in D and Y
Sistemas de energía eólica y solar para la alimentación de luminarias
No full textTrabajo de investigaciónEl siguiente documento trata de un estudio sobre cuál, de los sistemas de energías
fotovoltaicas o eólicas, es más eficiente para la alimentación de dispositivos de baja
potencia, luminarias tipo led. Se realizan pruebas en dos sitios distintos pertenecientes
a la localidad de Usme al sur de Bogotá, el primer sitio una zona residencial y el
segundo un campo abierto o zona verde.PregradoIngeniero ElectrónicoINTRODUCCIÓN
1. GENERALIDADES
2. RECOPILACIÓN DE LA INFORMACIÓN
3.CARACTERÍSTICAS PARA LA IMPLEMENTACIÓN DE LOS SISTEMAS DE ENERGÍA.
4.IMPLEMENTACIÓN DE LOS SISTEMAS
5.DATOS RECOLECTADOS
6.DETERMINAR CUAL DE LAS ENERGÍAS ES MAS EFICIENTE 7.CONCLUSIONES
8.RECOMENDACIONES
9.BIBLIOGRAFÍ
Attitudes de prise en charge de la myopie chez les enfants dans la pratique clinique au Maroc
No full textLa myopie est un problème mondial de santé publique et avec sa prévalence croissante, on s’intéresse de plus en plus à sa prévention précoce. Cependant il y a un manque d’informations sur les interventions adoptées par les professionnels de la santé visuelle à l’échelle Marocain pour la prise en charge de la myopie chez les enfants, cette étude vise à évaluer leurs connaissances et à les sensibiliser sur l’impact des facteurs environnementaux susceptibles d’influencer le risque de la progression de la myopie. Afin d’atteindre ces objectifs, une enquête en ligne a été distribuée aux spécialistes de la vue du pays, comprend un questionnaire évaluant leur maîtrise des différentes méthodes disponibles pour le traitement de la myopie, leur niveau de préoccupation face à son évolution chez les enfants ainsi que leur opinion sur l’impact des facteurs environnementaux sur son apparition et sa croissance. Les résultats indiquent que la plupart des professionnels consultés sont préoccupés par cette pandémie, cependant ils ne proposent actuellement que des verres simples foyer et des lentilles de contact souples ce qui indique la nécessité de formations professionnelles visant à éduquer les spécialistes aux approches cliniques de gestion de la myopie. Cela les encouragerait à adopter d’autres solutions pour prendre en charge les enfants myopes et à accorder une attention particulière aux facteurs environnementaux qui influent sur l’apparition et la progression de la myopie
Output Power Estimation of High Concentrator Photovoltaic Using Radial Basis Function Neural Network
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