oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 146 )

2018 ( 189 )

2017 ( 167 )

2016 ( 240 )

Custom range...

Search Results: 1 - 10 of 13200 matches for " Elías; "
All listed articles are free for downloading (OA Articles)
Page 1 /13200
Display every page Item
Effect of the Number and Orientation of Fractures on the P-Wave Velocity Diminution: Application on the Building Stones of the Rabat Area (Morocco)  [PDF]
Hamid El Azhari, Iz-Eddine El Amrani El Hassani
Geomaterials (GM) , 2013, DOI: 10.4236/gm.2013.33010
Abstract: This study is focused on two types of Moroccan rocks, among the most widely used as building stones: the calcarenite of Salé (CS) and the marble of oued Akrech (MA). The two rocks, lithologically different, show a clear contrast of their P-wave velocities (Vp): 3.90 vs 5.10 km/s at dry state and 4.29 vs 5.64 km/s at saturation. The “Artificial fractures” created in the two rock types reveal that their Vp undergo diminutions which the rates vary depending of the number and the plane orientation of the fractures. In the CS, Vp shows an increasing of cumulative diminution (Dc) according to the number of fractures, but with a variable rate of unitary diminution (Du) from one fracture to the other. This defines a linear regression with a low coefficient of determination (Dc = 10.18NbFr + 10.96; r2 = 0.87). The mode of the Vp evolution would be related to the roughness of fractures surface, which itself depends upon the petrographic nature of the calcarenite (friable structure, high porosity and heterogenous composition). The MA manifested an increasing Dc with a fairly constant rate of Du from a fracture to another, giving a regression line with a high coefficient of determination (Dc = 12.17NbFr10.69; r2 = 0.99). This steady diminution of Vp would be related to the granoblastic texture and the monomineral composition of the marble, which engender smoother fracture surfaces. The rates of Vp diminution also depend on the orientation plane of the fractures relative to the direction of wave propagation. The fractures parallel (θ = 0°) amplify slightly the Vp, playing a significant role of “waveguide”. The fractures oriented at 45° lead to a diminution lower than those of fractures oriented at 25° and 90°. The same trend of diminution, but at variable rates, appears on the samples of the two types of stones at dry and saturated state. This can be explained by the compressive nature of P-waves, which obey the physic laws of the transmission of the constraints in the solid mediums.
Waterlogging in the New Reclaimed Areas Northeast El Fayoum, Western Desert, Egypt, Reasons and Solutions  [PDF]
El Sayed Ali El Abd, Maged Mostafa El Osta
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.618147
Abstract: The waterlogging in the new reclaimed areas has become a major concern in the area Northeast El Fayoum, Western Desert, Egypt. It is not only endangering the structures and properties but also causing major environmental problem affecting the health of the area, habitats, and the biotic of the land community, as well as the deteriorating of Egypt’s Pharaonic monuments (El Lahun and Hawarah pyramids). Both the daily seepage from excess irrigation water and the presence of impervious clay or limestone beds at shallow depths may represent the main contributor of ground-water rising in the shallow aquifer. This paper investigates the interplay of the hydrogeological characteristics, soil properties and recent land reclamation projects on the distribution of waterlogging and salinization within the study area. The field observations show that new reclaimed areas have been recently cultivated in distant areas from the old agricultural land. These new cultivations have developed widespread waterlogging, soil salinization and deterioration of Egypt’s Pharaonic monuments as a result of rising groundwater related problems. In this paper, the data used come from database of drillings for eleven observation wells distributed inside the whole area to measure periodic water levels. The soil litho-units are mainly composed of coarse sand, sandy clay, silt and fractured limestone underlined by impervious clay or limestone, thus limiting the downward percolation of excess irrigation water and therefore develops waterlogging. The drainage networks and suitable irrigation methods have to be considered when planning for a new cultivation in dry land to better control waterlogging and salinization hazard. It is highly recommended in this research that newly small and deep cut drainage canals network should be constructed and connected to the master drainage canal to dewater the excess irrigation water and to prevent the waterlogging in the concerned area.
On Elliptic Problem with Singular Cylindrical Potential, a Concave Term, and Critical Caffarelli-Kohn-Nirenberg Exponent  [PDF]
Mohammed El Mokhtar Ould El Mokhtar
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.611166
Abstract: In this paper, we establish the existence of at least four distinct solutions to an elliptic problem with singular cylindrical potential, a concave term, and critical Caffarelli-Kohn-Nirenberg exponent, by using the Nehari manifold and mountain pass theorem.
Four Nontrivial Solutions for Kirchhoff Problems with Critical Potential, Critical Exponent and a Concave Term  [PDF]
Mohammed El Mokhtar Ould El Mokhtar
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.614198
Abstract: In this paper, we consider the existence of multiple solutions to the Kirchhoff problems with critical potential, critical exponent and a concave term. Our main tools are the Nehari manifold and mountain pass theorem.
PP and PP Multi-Particles Production Investigation Based on CCNN Black-Box Approach  [PDF]
El-Sayed A. El-Dahshan
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.56115
Abstract: The multiplicity distribution (P(nch)) of charged particles produced in a high energy collision is a key quantity to understand the mechanism of multiparticle production. This paper describes the novel application of an artificial neural network (ANN) black-box modeling approach based on the cascade correlation (CC) algorithm formulated to calculate and predict multiplicity distribution of proton-proton (antiproton) (PP and PP ) inelastic interactions full phase space at a wide range of center-mass of energy \"\". In addition, the formulated cascade correlation neural network (CCNN) model is used to empirically calculate the average multiplicity distribution <nch> as a function of \"\". The CCNN model was designed based on available experimental data for \"\"= 30.4 GeV, 44.5 GeV, 52.6 GeV, 62.2 GeV, 200 GeV, 300 GeV, 540 GeV, 900 GeV, 1000 GeV, 1800 GeV, and 7 TeV. Our obtained empirical results for P(nch), as well as <nch> for (PP and PP) collisions are compared with the corresponding theoretical ones which obtained from other models. This comparison shows a good agreement with the available experimental data (up to 7 TeV) and other theoretical ones. At full large hadron collider (LHC) energy ( \"\"= 14 TeV) we have predicted P(nch) and <nch> which also, show a good agreement with different theoretical models.
Multiple Solutions to the Problem of Kirchhoff Type Involving the Critical Caffareli-Kohn-Niremberg Exponent, Concave Term and Sign-Changing Weights  [PDF]
Mohammed El Mokhtar Ould El Mokhtar
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.811123
Abstract:
In this paper, we establish the existence of at least four distinct solutions to an Kirchhoff type problems involving the critical Caffareli-Kohn-Niremberg exponent, concave term and sign-changing weights, by using the Nehari manifold and mountain pass theorem.
Anterior Screw Fixation in Type II Odontoid Fractures: Keys for Better Outcome in Early Experience in Developing Countries  [PDF]
Ahmed El Fiki, Hisham El Shitany
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.84031
Abstract: Introduction: Representing up to 15% of cervical injuries, odontoid type II fractures may cause spinal cord compression through atlanto-axial instability. Anterior screw fixation provides direct fracture site stability, high fusion rate and most importantly keeping cervical spine move free. We will highlight success keys in early experience for better outcome. Methods: We operated ten cases with traumatic type II odontoid fractures in neurotrauma unit, Cairo University hospitals from March 2015 till June 2017. Six males and four females were included. Preoperative MRI and dynamic CT were among the assessment criteria. Uni-planner fluoroscopy was used. Results: No post-operative deficit appeared. One screw was inserted in all cases. Immediate and 6 weeks later CT cervical spine showed stable reduced fracture site. Conclusions: Anterior odontoid screw fixation done with prior good selection of the patient and fracture shape is an effective motion preserving surgical option for type II odontoid fractures. Limited resources shouldn’t prevent starting experience especially in developing countries, but larger studies are needed.
Effect of Urbanization and Industrialization Processes on Outdoor Thermal Human Comfort in Egypt  [PDF]
El-Sayed ROBAA
Atmospheric and Climate Sciences (ACS) , 2011, DOI: 10.4236/acs.2011.13012
Abstract: Detailed studies on the effect of urbanization and industrialization processes on outdoor thermal human com- fort in Greater Cairo region, Egypt have been performed in this study. Four different districts in Greater Cairo region have been selected to represent rural, suburban, typical urban and industrial areas. The data of surface dry, wet bulb temperatures and wind speed for two different periods represent non-urbanized and urbanized periods have been used. Discomfort indices for the two periods have been calculated for the four districts. The study revealed that urbanization and industrialization processes have resulted in the distinctly modification of human comfortable at all districts. The feeling of quite comfortable reduced from the old non-urbanized period to the recent urbanized period at the four districts. During the recent urbanized period, the rural area has the highest total number of quite comfortable hours while both urban and industrial areas have the lowest total number of hours. The serious hot uncomfortable didn’t occur at all districts during the old non-urbanized period while during the recent urbanized period, all people had felt extreme serious hot uncomfortable only at urban and industrial areas. It could be concluded that the urbanization and industriali-zation processes cause increase of human serious hot uncomfortable feeling which in turn leads to more hin-dering for the human activities while the rural conditions leads to optimum weather comfort for further and more human activities.
Power Density and SAR in Multi-Layered Life Tissue at Global System Mobile (GSM) Frequencies  [PDF]
Khitam El Wasife
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2011, DOI: 10.4236/jemaa.2011.38052
Abstract: In this paper, the power density and specific absorption rate (SAR) distribution in multi-layered life tissues and exposed to electromagnetic field emitted from handheld cellular phone operating in the 900 MHz and 1800 MHz is studied. We modeled a life tissue by four layered system to represent skin-fat-muscles-organs respectively. Matlab program and finite difference time domain (FDTD) computations were used to evaluator the electric, magnetic field, power density and specific absorption rate. A one dimensional FDTD algorithm has been built, some simulations for electromagnetic wave through the life tissue is made. Results show that electro magnetic fields penetrate the life tissues and attenuate fast to reach zero at the organs layer. The absorbent power and SAR show maximum at the skin and fat layers.
Virtual water: an effective mechanism for integrated water resources management  [PDF]
Alaa El-Sadek
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.23033
Abstract: In regions, which suffer from water shortage or potential water shortage like the Middle East, water policies and different mitigation measures are formulated. With the increasing population and increasing demand for food and drinking water with the fixed supply of water, the demand management policies have been introduced. Virtual Water has been adopted as an alternative or potential alternative water resource. In the application of the Integrated Water Resources Management (IWRM), virtual water has to be considered as a resource of water. In this paper, the practical value of the virtual water concept as well as the possibility of the application of the concept in the regional and national level are discussed. The paper emphasizes on the application of virtual water in agriculture products and virtual water trade of these products. This research concluded that, there is a possibility for the application of the virtual water concept on the national level taking into account water endowments, and other natural and social economic conditions. The virtual water strategy seeks ways to consciously and efficiently utilize the internal and external water resources to alleviate water scarcity. This, however, by no means implies that importing food is the only response the water scarce countries and regions should and can take. Other measures concerning the supply and demand sides of water management are imperative. The argument here is that the virtual water strategy should be an integral component in the whole package of integrated water resources management.
Page 1 /13200
Display every page Item


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