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Search Results: 1 - 10 of 484008 matches for " C. S.;Teider "
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A geopolimeriza??o como técnica para a aplica??o do resíduo de bauxita
Bitencourt, C. S.;Teider, B. H.;Gallo, J. B.;Pandolfelli, V. C.;
Ceramica , 2012, DOI: 10.1590/S0366-69132012000100005
Abstract: finding sustainable applications for the bauxite residue is one of the leading challenges in the aluminium industry. for this purpose, the geopolymerization could become an interesting alternative, because this technique could make use of some of the typical characteristics of the bauxite residue, such as its alkalinity and expressive silicates and aluminates contents, resulting in solid materials with similar properties to usual traditional ceramics. in this work, the properties, processing and possible applications of such materials were analyzed. besides the apparent porosity and the mechanical resistance tests, the obtained samples were also submitted to a leaching test, aiming to a preliminary evaluation of the potential environmental risks of application that a supposed product would represent, and which procedures could favour its passivation. as the main results, it was possible to verify that firing at 800 °c allowed some compositions to reach compression resistance values up to 30 mpa, and a leaching resistance closer to a common pressed clay brick, which makes the building materials a potential area of application for the bauxite residue geopolymers, based on the enormous consumption capacity of this area and its increasing demand for more sustainable products.
Sele??o de refratários para fornos de cozimento de anodo
Tiba, P. R. T.;Teider, B.H.;Figueiredo, F.;Gallo, J. B.;Pandolfelli, V. C.;
Ceramica , 2009, DOI: 10.1590/S0366-69132009000100016
Abstract: in the latest years, the worldwide production of aluminum is increasing and for the companies to keep their competitiveness it is necessary to reduce the average cost of the metal production. one of the alternatives is to increase the refractories working life used in anode baking furnaces and their production capacity. both strategies may result in a higher anode quality and reduction of the furnace maintenance costs. this paper aims to present the thermo-mechanical characterization of the refractory bricks used in anode baking furnaces and their resistance to chemical attack. the results indicated that the selection of the most suitable composition depends on a systemic analysis involving the high temperature properties, chemical resistance and the operational practices of the furnace.
Sele??o de refratários para fornos de cozimento de anodo
Tiba, P. R. T.;Teider, B. H.;Figueiredo, F.;Gallo, J. B.;Pandolfelli, V. C.;
Ceramica , 2009, DOI: 10.1590/S0366-69132009000300010
Abstract: in the latest years the worldwide production of aluminum is increasing and for the companies to keep their competitiveness it is necessary to reduce the average cost of the metal production. one of the alternatives is to increase the refractories working life used in anode baking furnaces and their production capacity. both strategies may result in a higher anode quality and reduction of the furnace maintenance costs. this paper aims to present the thermo-mechanical characterization of the refractory bricks used in anode baking furnaces and their resistance to chemical attack. the results indicated that the selection of the most suitable composition depends on a systemic analysis involving the high temperature properties, chemical resistance and the operational practices of the furnace.
Hecke actions on certain strongly modular genera of lattices
Gabriele Nebe,Maria Teider
Mathematics , 2005, DOI: 10.1007/s00013-004-1288-4
Abstract: We calculate the action of some Hecke operators on spaces of modular forms spanned by the Siegel theta-series of certain genera of strongly modular lattices closely related to the Leech lattice. Their eigenforms provide explicit examples of Siegel cusp forms.
Aplica??o da ferramenta SWOT para avalia??o das técnicas de dano ao choque térmico em materiais refratários
Gon?alves, L. R. G.;Cintra, G. B.;Teider, B. H.;Gallo, J. B.;Pandolfelli, V. C.;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000400002
Abstract: the literature shows different tests and techniques for evaluating the thermal shock damage. additionally, it is known that, for certain applications, this type of wear mechanism is one of the main causes of fluid flash calciner refractory degradation. within this context and in order to find the best way to reproduce the refractory lining service conditions, this work was carried out to point out which thermal shock test and damage assessment method are more suitable to evaluate these materials. this analysis was based on a literature review and laboratory experiments, comparing and evaluating the advantages and disadvantages of the most important methods available. finally, with the support of the swot tool it was possible to evaluate whether the method adopted by the authors of this work is appropriated for helping the selection of the refractories for calciners application.
An EPQ Model with Imperfect Production Systems with Rework of Regular Production and Sales Return  [PDF]
C. Krishnamoorthi, S. Panayappan
American Journal of Operations Research (AJOR) , 2012, DOI: 10.4236/ajor.2012.22026
Abstract: The Economic Production Quantity (EPQ) model is commonly used by practitioners in the fields of production and inventory management to assist them in making decision on production lot size. The common assumptions in this model are that all units produced are perfect and shortages are not allowed. But, in real situation the defective items will be produced in each cycle of production and shortages and scrap are possible. These assumptions will underestimate the actual required quantity. Hence, the defective items can not be ignored in the production process. Rework process is necessary to convert those defective into finished goods. This study proposes EPQ model that incorporates both imperfect production quality and falsely not screening out a proportion of defects, thereby passing them on to customers, resulting in defect sales returns. To active this objective a suitable mathematical model is developed and the optimal production lot size which minimizes the total cost is derived. An illustrative example is provided and numerically verified. The validation of result in this model was coded in Microsoft Visual Basic 6.0.
Influences on the study of Vulvar Anatomy and Disease  [PDF]
Ian S. C. Jones
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.23045
Abstract: The study of Gynaecology over the years has been influenced by the culture and social attitudes of society to the body as a whole and to the genital organs in particular. Variations in these attitudes between different cultures and at different times have influenced the subsequent rate of progress in the study of the vulva and its diseases.
Melanosis of the vulva: A long-term follow-up from Brisbane, Australia  [PDF]
Ian S. C. Jones
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.23051
Abstract: Object: To determine if vulvar melanosis progressed to melanoma over a period of 20 years or more. Methods: In 2010 the hospital records from the Royal Brisbane Hospital Vulvar Clinic between 1976 and 1988 were reviewed and cross checked with the state wide Queensland Centre for Gynaecological Cancer (QCGC) data base to determine if any patient had been lost to follow up and subsequently developed a vulvar melanoma. Data collected were stored and analysed using the computer software Statistical Package for the Social Sciences (SPSS) 11.0. Results: None of the 12 patients developed vulval melanoma in the years up to 2010. Conclusion: In this small group, followed for more than 20 years, melanosis was not a precursor of melanoma. One patient, who attended the Vulvar Clinic but was not included in this melanosis study, was found to have co-existing melanosis well away from her melanoma in situ and malignant melanoma at presentation. It was not possible to determine if these findings represented a progression of the benign to malignant. Biopsy of abnormal hyper pigmented vulvar skin is recommended. Current knowledge suggests that vulvar melanosis is a benign condition but to be on the safe side follow up of all hyper pigmented vulval lesions to detect early malignant change is recommended.
A review of conditions altering the permanent appearance of the vulva  [PDF]
Ian S. C. Jones
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.24078
Abstract: This article is aimed at providing information on variations in the clinical appearance of the vulva. The appearance of the vulva can be altered by reversible or permanent conditions both of which may result in minor or major changes. Reversible conditions include those associated with infections or acute trauma which results in distortion of the vulva. Some permanent changes are caused by life threatening conditions which are present at birth whereas others develop more slowly or as the result of a deliberate act either traditional female surgery or surgery performed by a registered medical practitioner. To the inexperienced practitioner changes from the normal vulvar appearance can be confusing. The aim of this article is to highlight and categorise changes that can affect the appearance of the vulva. Whatever the presentation the importance of obtaining a detailed history and performing an appropriate, sensitive and thorough examination can not be over emphasised.
A Novel Approach to Study Regional Ionospheric Variations Using a Real-Time TEC Model  [PDF]
S. C. Chakravarty
Positioning (POS) , 2014, DOI: 10.4236/pos.2014.51001
Abstract:

Since IGY (International Geophysical Year), through coordinated global observations, ionospheric research has been carried out by many countries. This effort primarily helped in the design and operation of HF radio wave communication systems. The Indian region covers a highly variable part of the equatorial electrojet and EIA (Equatorial Ionisation Anomaly) phenomena making its predictability difficult. With the advent of satellite communication and navigation, the need for accurate ionospheric TEC (Total Electron Content) models at global and regional scales has been stressed. The GAGAN (GPS Aided Geo Augmented Navigation) project jointly undertaken by the Indian Space Research Organisation (ISRO) and the Airport Authority of India (AAI) aims at effectively utilising the Global Navigational Satellite System (GNSS) to determine position coordinates accurately for aircraft precision landing applications. For this purpose the range errors are estimated by using a ground network of TEC stations spread over Indian region. The near simultaneous data collected from these dual frequency GPS stations can be used to generate the geo-referenced TEC values for various applications. The author has developed necessary algorithm and associated computer programmes for a real-time vertical TEC (VTEC) model based on TEC data collected from the GAGAN ground based network stations. The model has been tested and sample results presented here show that it adequately provides for the latitudinal resolution of 1° for the entire longitude span and also for two longitude blocks (73 - 83 & 83 - 93°E) separately. Cubic spline and bilinear interpolation techniques are used for filling up temporal and spatial data gaps. The model provides tabulated output of hourly average VTEC data with latitude for ready use, as well as graphical displays of VTEC maps and contours for monitoring purpose. The real-time model and its extensions are also being used for detailed scientific studies; examples of these show small day to day variability of VTEC without any change in solar activity and indication of the change in the shape of the VTEC diurnal curve with season. The present model will be used for further studies to derive the monthly average variation of the diurnal pattern and the relationship between VTEC peak amplitudes with changes in solar activity. The

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