oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2018 ( 5 )

2017 ( 784 )

2016 ( 1230 )

2015 ( 14655 )

自定义范围…

匹配条件: “El-Sayed A. Abo-Tabl” ,找到相关结果约469666条。
列表显示的所有文章,均可免费获取
第1页/共469666条
每页显示
On Links between Rough Sets and Digital Topology  [PDF]
El-Sayed A. Abo-Tabl
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.56089
Abstract:

Rough set theory is a powerful tool for dealing with uncertainty, granularity, and incompleteness of knowledge in information systems. In addition, digital topology deals with properties and features of two-dimensional or three-dimensional digital images that correspond to topological properties of objects. So, we try to describe the relationship between rough sets and digital topology. Firstly, we will study the classifications of topologies in rough sets. Secondly, we will use the upper approximation operator to span the digital line, which is the basic building block of the digital spaces.

Properties and durability of metakaolin blended cements
Abo-El-Enein, Salah A.,Abbas, Rafik,Ezzat, El-Sayed
Materiales de Construccion , 2010,
Abstract: This paper evaluates the optimal calcination temperature and replacement ratio to ensure high metakaolin (MK) pozzolanicity in blended cement. The MK used was prepared by firing two types of local at temperatures ranging from 700 to 850 oC. Dry blends of ordinary Portland cement (OPC) and varying proportions of MK were mixed with the amount of water required to ensure optimal consistency of the resulting pastes. The specimens were cured at 100% RH for 24 h and then immersed in water for 3, 7, 28, 90 or 180 days. At each test time, the degree of hydration and compressive strength of the hardened cement pastes were measured The findings showed that the most suitable calcination temperature to obtain metakaolin is 700 oC, while the optimal replacement ratio ranges from 25 to 30%. DTA was used to determine the phases comprising the hydration products forming at the ages studied. Pure OPC and OPC-MK specimens were immersed in 3% NaCl and 5% MgSO4 solutions for 30, 90 and 180 days to measure their durability. The OPC-MK pastes immersed in the 3% NaCl solution were observed to be highly resistant to chloride attack. El presente trabajo evalúa el comportamiento puzolánico de metacaolín (MK), producto de la calcinación a distintas temperaturas de dos tipos de caolín local de composiciones químicas diferentes, al incorporarse al cemento en diferentes proporciones. Se preparó un cemento adicionado mediante la mezcla en seco de cemento Portland ordinario (OPC) y metacaolín (MK), a los que se a adió la cantidad óptima de agua para obtener una pasta de la consistencia deseada. Las probetas se curaron a una HR del 100% durante 24 horas, sumergiéndose posteriormente en agua durante 3, 7, 28, 90 o 180 días. A cada tiempo de ensayo se controló el grado de hidratación de las pastas endurecidas y se comprobó la resistencia a la compresión de las probetas cúbicas a las edades de curado establecidas. Los resultados obtenidos indican que la temperatura más adecuada para la calcinación del caolín es de 700 °C y que el porcentaje óptimo de éste en la mezcla se encuentra entre el 25 y el 30%. Las fases que componen los productos resultantes de la hidratación se identificaron mediante ATD a distintas edades de curado. Se estableció la durabilidad del OPC puro y de las mezclas de OPC-MK en disoluciones de NaCl al 3% y MgSO4 al 5% tras 30, 90 y 180 días de inmersión. Se concluyó que las pastas de OPC-MK muestran una elevada resistencia al ataque del ion cloruro.
Properties and durability of metakaolin blended cements: mortar and concrete
Abbas, Rafik,Abo-El-Enein, Salah A.,Ezzat, El-Sayed
Materiales de Construccion , 2010,
Abstract: This article explores the effect of metakaolin, a pozzolan, on concrete performance. Compressive and splitting tensile strength were found for specimens cured for up to 360 and 90 days, respectively. Changes were recorded in the compressive strength of specimens exposed to salt (chloride and sulfatechloride solutions), and chloride penetration and binding capacity were measured. The findings were compared to the results for concrete prepared with ordinary Portland (OPC) and moderate heat of hydration (Type II) cement. MK was found to have a very positive effect on 28-day concrete strength, due to microstructure improvement of the hydrated cement. Replacing cement with metakaolin effectively raised concrete resistance to chloride attack. Concrete containing metakaolin proved to be substantially more durable in sulfate-chloride environment. En este trabajo se estudia el efecto del metacaolín sobre las prestaciones del hormigón. Las probetas curadas a 360 y 90 días se sometieron a ensayos de resistencia a compresión y de tracción indirecta respectivamente. Se hizo un seguimiento de la resistencia a la compresión de los materiales ante el ataque de sales (soluciones de cloruro y de sulfato-cloruro) y, se midió la penetración de cloruros y la capacidad de los hormigones de inmovilizar estos iones. Los resultados se compararon con los obtenidos con hormigones elaborados con cemento pórtland ordinario (OPC) y, con cemento de calor de hidratación moderado (tipo II). El MK resultó influir muy positivamente en la resistencia del hormigón a 28 días debido a la mejora de la microestructura del cemento hidratado. La sustitución de cemento por metacaolín aumentó la resistencia del hormigón al ataque de cloruros. El hormigón con metacaolín demostró ser más duradero en entornos de sulfato-cloruro que los hormigones elaborados con OPC o con cemento de tipo II. Los perfiles de concentración de cloruros a distintas profundidades y la diferencia entre los contenidos de cloruro libre y total, mostraron claramente que el cemento con metacaolín reducía la penetración de cloruros en el hormigón y, aumentaba su capacidad para combinar con iones cloruro. La conclusión general fue que podía fabricarse material puzolánico utilizable, mediante la activación térmica del caolín local.
New Architecture of Optical Interconnect for High-Speed Optical Computerized Data Networks (Nonlinear Response)
El-Sayed A. El-Badawy,Farag Z. El-Halafawy,Hamdy A. Kelash,Ashraf M. Abou-Tabl
Journal of Systemics, Cybernetics and Informatics , 2008,
Abstract: Although research into the use of optics in computers has increased in the last and current decades, the fact remains that electronics is still superior to optics in almost every way. Research into the use of optics at this stage mirrors the research into electronics after the 2nd World War. The advantages of using fiber optics over wiring are the same as the argument for using optics over electronics in computers. Even through totally optical computers are now a reality, computers that combine both electronics and optics, electro-optic hybrids, have been in use for some time. In the present paper, architecture of optical interconnect is built up on the bases of four Vertical-Cavity Surface- Emitting Laser Diodes (VCSELD) and two optical links where thermal effects of both the diodes and the links are included. Nonlinear relations are correlated to investigate the power-current and the voltage-current dependences of the four devices. The good performance (high speed) of the interconnect is deeply and parametrically investigated under wide ranges of the affecting parameters. The high speed performance is processed through three different effects, namely the device 3-dB bandwidth, the link dispersion characteristics, and the transmitted bit rate (soliton). Eight combinations are investigated; each possesses its own characteristics. The best architecture is the one composed of VCSELD that operates at 850 nm and the silica fiber whatever the operating set of causes. This combination possesses the largest device 3-dB bandwidth, the largest link bandwidth and the largest soliton transmitted bit rate. The increase of the ambient temperature reduces the high-speed performance of the interconnect
Study of Similarity Measures with Linear Discriminant Analysis for Face Recognition  [PDF]
Mohamed A. El-Sayed, Kadry Hamed
Journal of Software Engineering and Applications (JSEA) , 2015, DOI: 10.4236/jsea.2015.89046
Abstract: Face recognition systems have been in the active research in the area of image processing for quite a long time. Evaluating the face recognition system was carried out with various types of algorithms used for extracting the features, their classification and matching. Similarity measure or distance measure is also an important factor in assessing the quality of a face recognition system. There are various distance measures in literature which are widely used in this area. In this work, a new class of similarity measure based on the Lp metric between fuzzy sets is proposed which gives better results when compared to the existing distance measures in the area with Linear Discriminant Analysis (LDA). The result points to a positive direction that with the existing feature extraction methods itself the results can be improved if the similarity measure in the matching part is efficient.
Experimental Study of Heat Transfer to Flowing Air inside a Circular Tube with Longitudinal Continuous and Interrupted Fins  [PDF]
Saad A. El-Sayed, Sayed A. EL-Sayed, Mohamed M. Saadoun
Journal of Electronics Cooling and Thermal Control (JECTC) , 2012, DOI: 10.4236/jectc.2012.21001
Abstract: Experimental investigations have been performed to determine the detailed module-by-module pressure drop and heat transfer coefficient of turbulent flow inside a circular finned tube. The tubes are provided with longitudinal fins continuous or interrupted in the stream wise direction by arranging them both in a staggered and in-line manner. Experiments are carried out for two different fin geometries, with two numbers of fins (N = 6 and 12). All tested finned tubes have 16 modules each with length equal to the tube diameter (L = D = 30 mm). The thermal boundary condition considered here, is a uniform heat flux. The module-by-module heat transfer coefficient is found to vary only in the first modules, and then attained a constant thermally periodic fully developed value after eight to twelve modules. The results also showed that in the periodic hydrodynamic fully developed region, the value of the pressure drop along the tube with continuous fins is greater than that of the in-line arrangement, and lower than that of the staggered arrangement. Furthermore, the results showed that in the periodic fully developed region, the tube with continuous fins produces a greater value of the heat transfer coefficients than that the tube with interrupted fins, especially through a high range of Reynolds number (5 × 104 > Re > 2 × 104). The tube with Staggered arrangement of fins produces a greater value of the heat transfer coefficient than the tube with continuous fins and the in-line arrangement finned tube at low Reynolds number (Re < 1.2 × 104).). It was found that the fins efficiency is greater than 90 percent; in the worst case (maximum Reynolds number with continuous fins tube).
Resistance of Alkali Activated Water-Cooled Slag Geopolymer to Sulphate Attack
H. A. El-Sayed,S. A. Abo El-Enein,H. M. KHATE R,S. A. Hasanein
Ceramics-Silikáty , 2011,
Abstract: Ground granulated blast furnace slag is a finely ground, rapidly chilled aluminosilicate melt material that is separated from molten iron in the blast furnace as a by-product. Rapid cooling results in an amorphous or a glassy phase known as GGBFS or water cooled slag (WCS). Alkaline activation of latent hydraulic WCS by sodium hydroxide and/or sodium silicate in different ratios was studied. Curing was performed under 100 % relative humidity and at a temperature of 38°C. The results showed that mixing of both sodium hydroxide and sodium silicate in ratio of 3:3 wt.,% is the optimum one giving better mechanical as well as microstructural characteristics as compared with cement mortar that has various cement content (cement : sand were 1:3 and 1:2). Durability of the water cooled slag in 5 % MgSO4 as revealed by better microstructure and high resistivity-clarifying that activation by 3:3 sodium hydroxide and sodium silicate, respectively is better than using 2 and 6 % of sodium hydroxide.
Enhancement of Human Blood Storage Period by Irradiation of Low Level He-Ne Laser  [PDF]
Samira M. Sallam, Abdelsattar M. Sallam, El-Sayed M. El-Sayed, L. I. Abo Salem, Mona M. Rizk
Journal of Biophysical Chemistry (JBPC) , 2015, DOI: 10.4236/jbpc.2015.63008
Abstract: The aim of the present work is to investigate the effect of the He-Ne laser irradiation on the whole human blood (HB) in order to enhance the conditions of conservation. The HB was irradiated by He-Ne laser; (λ = 632 nm, continuous wave, power 30 mW, 2 mm diameter beam spot), electrical properties and complete blood count CBC were measured at three doses (0.0287, 0.0563 and 0.198 J/cm3) to the relevant best exposure dose during storage periods 9, 24, 30, 35 & 50 days. The irradiation process with the selected dose was performed by the exposure of the laser beam on the blood sample flow through narrow tube of cross section area, 0.0831 cm2. Blood dielectric parameters, (electric conductivity, dielectric constant, dielectric loss and dipole moment) and CBC, (red blood cell, white blood cell, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, and mean cell or corpuscular hemoglobin in concentration) were measured. The obtained results were compared with that of the control and showed that the best irradiation exposure dose suitable for increasing the time of blood storage with minimum changes in properties is 0.198 J/cm3 and storage period of about 50 days. The present study revealed that irradiation by He-Ne laser could be considered a good means to improve the conservation conditions of human blood.
Multi-Threshold Algorithm Based on Havrda and Charvat Entropy for Edge Detection in Satellite Grayscale Images  [PDF]
Mohamed A. El-Sayed, Hamida A. M. Sennari
Journal of Software Engineering and Applications (JSEA) , 2014, DOI: 10.4236/jsea.2014.71005
Abstract:

Automatic edge detection of an image is considered a type of crucial information that can be extracted by applying detectors with different techniques. It is a main tool in pattern recognition, image segmentation, and scene analysis. This paper introduces an edge-detection algorithm, which generates multi-threshold values. It is based on non-Shannon measures such as Havrda & Charvat’s entropy, which is commonly used in gray level image analysis in many types of images such as satellite grayscale images. The proposed edge detection performance is compared to the previous classic methods, such as Roberts, Prewitt, and Sobel methods. Numerical results underline the robustness of the presented approach and different applications are shown.

On-Chip Inductor Technique for Improving LNA Performance Operating at 15 GHz  [PDF]
El-Sayed A. M. Hasaneen, Nagwa Okely
Circuits and Systems (CS) , 2012, DOI: 10.4236/cs.2012.34047
Abstract: This paper presents a technique for low noise figure reduction of low-noise amplifier (LNA). The proposed LNA is designed in a source degeneration technique that offers lower noise figure. The resistance of the on-chip inductor is reduced by using multilayer that significantly reduces the thermal noise due to spiral inductor. Also, using spiral inductor as a gate inductor reduces the effect of the input parasitic capacitance on the noise figure and provides a good matching at the input and output of the LNA. The results of the LNA using multilayer on-chip inductor compared will off-chip inductor have been illustrated. It shows that the proposed technique reduces significantly the noise figure and improves the matching. The proposed LNA is designed in 0.13 μm process with 1.3 V supply voltage and simulated using Advanced Design System (ADS) software. The simulation results show that the LNA is unconditionally stable and provides a forward gain of 11.087 dB at operating frequency of 15 GHz with 1.784 dB noise figure and input and output impedance matching of –17.93 dB, and –10.04 dB.
第1页/共469666条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.