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Search Results: 1 - 10 of 10545 matches for " Ahmed Hussein "
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Evaluating Reference Crop Evapotranspiration (ETo) in the Centre of Guanzhong Basin—Case of Xingping & Wugong, Shaanxi, China  [PDF]
Hussein I. Ahmed, Junmin Liu
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55055
Abstract: In this paper, the Penman-Monteith method was applied to evaluate the reference crop evapotranspiration. A reliable estimation of the reference evapotranspiration (ETo) is of critical importance and required accurate estimates to close the water balance. The aim of this paper is estimating the reference evapotranspiration (ETo) as preliminary to use for groundwater modeling in the area. Based on FAO-Penman-Monteith method, ETo calculator software was applied. Meteorological data within this study were obtained from two gauges stations (Xing ping and Wu gong) and available literatures. The results indicated that the values of ETo for a period (1981-2009)29 yearsin two stations approximately the same. Specifically, is ranged between 0.4 - 6.9 mm /day, 0.4 - 6.7 mm/day and the average value is 2.6 mm/ day, 2.6 mm/day in Xing ping and Wu gong respectively. In addition, the maximum values were occurred in summer season (May, June and July). The result also found that the correlation coefficient ≈ 1. Moreover, “ETo” was increasing by recent years. The reference crop evapotranspiration for some crops were calculated.
Hydrogeochemical Variations of Groundwater of the Northern Jabal Hafit in Eastern Part of Abu Dhabi Emirate, United Arab Emirates (UAE)  [PDF]
Ahmed Murad, Faris Mahgoub, Saber Hussein
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.32046
Abstract: This study is aimed to assess and evaluate the suitability of groundwater of the area located to the south-east of Al-Ain area in the UAE using hydrogeochemcical approach. The chemical analyses of groundwater samples collected from the study area showed that the groundwater salinity is high which resulted from heavy groundwater pumping. High chloride concentrations in groundwater of Mubazarah and Neima might be attributed to the entrapped saline water within the limestone sequence of Jabal Hafit, or it can be the agricultural activities as it clear from the positive relationship between Cl- and Br-. High sulphate concentrations in groundwater might be related to the presence of gypsum and anhydrite within the limestone sequence of Jabal Hafit. The anionic and cationic compositions of groundwater indicate that the chloride and sodium ions are the dominant and presence of bicarbonate and sulphate may reflect the mixing of such water by the recent freshwater through the existing structural lineaments within the study area. The hydrochemical parameters indicate a relative increase in the concentration of calcium, magnesium and sulphate ions and this could reflect the influence of carbonates and evaporite sediments.
Changes in Platelet Indices during Pregnancy as Potential Markers for Prediction of Preeclampsia Development  [PDF]
Ahmed Mohamed Nooh, Hussein Mohammed Abdeldayem
Open Journal of Obstetrics and Gynecology (OJOG) , 2015, DOI: 10.4236/ojog.2015.512099
Abstract: Objective: To assess whether changes in platelet indices, detectable by simple complete blood count (CBC), during pregnancy could be used as markers for prediction of development of preeclampsia (PE). Methods: A total of 2813 pregnant women who received regular antenatal care until delivery were included. Participants were divided into 3 groups: normotensive pregnant women (n = 2621), women with PE without severe features (n = 169), and women with PE with severe features (n = 23). Blood samples were collected during antenatal visits and/or during the period of in-patient hospital stay, and changes in platelet indices were compared among the three groups. Results: Platelet count (PC) was decreasing while mean platelet volume (MPV) and platelet distribution width (PDW) were increasing as PE progressed. Receiver operating characteristics (ROC) curve analysis showed that PDW had the largest area under curve (AUC) [0.980 (95% CI: 0.964 - 1.000)], making it the best marker for predicting development of PE. Also, PDW showed the most statistically significant correlation with mean arterial pressure (MAP) (r = 0.902, p = 0.000), making it the best marker for predicting severity of hypertension. Conclusion: This study provides evidence that PC decreases while MPV and PDW increase as pregnancy advances, and these changes are more pronounced in PE than normotensive pregnancy. These changes predate development of PE by 2 - 8 weeks and are proportional to the progress of this disorder. The selected platelet indices, especially PDW, have the potential to be utilized as markers for not only prediction of PE development but also severity of hypertension.
The multiplicity of particle production from hadron-hadron and nucleus-nucleus interaction  [PDF]
Ahmed Abdo Ahmed Al-Haydari, Mohmmed Tarek Hussein
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.24047
Abstract: The particle production in hadron-nucleon (h-N), hadron-nucleus (h-A) and nucleus-nucleus (A-A) collisions at high energies are studied in view of the multi-peripheral model. A multi-peripheral T-matrix element is assumed with multi surface parameter that is functionally dependent on the number of particles in the final state and control the kinematical path of the reaction. A Monte Carlo code is designed to simulate events ac-cording to a hypothetical model, the quark structure of the interacting nucleons is consid-ered. The number of possible nucleon collisions inside the target nucleus plays an important role in folding the (h-N) to generate the (h-A) and (A-A) collisions. The predictions of the model give reasonable agreement with the recently examined experimental data.
Conical Linear Spiral Antenna for Tracking, Telemetry and Command of Low Earth Orbit Satellites
Khalid Fawzy Ahmed Hussein
PIER C , 2012, DOI: 10.2528/PIERC12031610
Abstract: Conical log spiral antennas are famous for being appropriate for tracking, telemetry and command (TT&C) applications in low earth orbit (LEO) satellites. In this work, a conical linear (not log) spiral antenna is introduced and investigated for the same purpose. The electric field integral equation (EFIE) technique is applied to a triangular-patch surface model of the conical equiangular linear spiral antenna. This antenna is optimized to produce the radiation characteristics required for TT&C applications for LEO satellites. The input impedance, polarization and radiation patterns of this antenna are investigated over a wide band of frequencies. Some of the obtained results especially those concerning the input impedance, radiation pattern, polarization and bandwidth are verified experimentally. It is shown that the proposed antenna is quite appropriate for TT&C in LEO satellite applications.
Efficient Near-Field Computation for Radiation and Scattering from Conducting Surfaces of Arbitrary Shape
Khalid Fawzy Ahmed Hussein
PIER , 2007, DOI: 10.2528/PIER07010302
Abstract: A new algorithm for numerical evaluation of the fields in the near zone of conducting scatterers or antennas of arbitrary shape is developed in the present work. This algorithm is simple, fast, robust andis basedon a preceding calculation of the current flowing on the conducting surface using the electric filed integral equation (EFIE) technique that employs the Rao-Wilton-Glisson (RWG) basis functions. To examine the validity of the near field computational algorithm developed in the present work, it is applied to calculate the near fieldd ue to plane wave incidence on a variety of conducting scatterers. The solution obtainedfor the fields in the near zone is found to satisfy the boundary conditions on both planar and curved scatterer surfaces and the edge condition for structures possessing edges or corners. The solutions obtainedusing the new algorithm are compared with those obtainedusing some commercial packages that employ the finite-difference-time-domain (FDTD). The algorithm defined in the present work gives results which are more accurate in describing the fields near the edges than the results obtained using the FDTD.
Effect of Internal Resonance on the Radar Cross Section and Shield Effectiveness of Open Spherical Enclosures
Khalid Fawzy Ahmed Hussein
PIER , 2007, DOI: 10.2528/PIER07012101
Abstract: In this paper, the effects of the internal resonances of an open conducting spherical enclosure with circular aperture on its radar cross section (RCS) and shield effectiveness (SE) are studied over a wide frequency band. The sizes of the spherical enclosures investigated in the present work range from electrically small (perimeter is less than the wavelength) to electrically large (perimeter is up to ten times the wavelength). It is shown that for such an enclosure, both the RCS and SE, as functions of frequency, have sharp spikes, minima, or maxima at the resonant frequencies corresponding to the internal modes of the closed conducting sphere. Principal and higher order modes are considered. The effects of the aperture width on the perturbation of the field inside and outside of the spherical enclosure, the near field outside the cavity, the RCS and the SE are presented over a wide range of frequency. It is shown that the sharpness and amplitude of the spikes, minima, or maxima of the RCS and SE are decreased with increasing the aperture width. Also, the resonant frequencies of the enclosed spherical cavity are shifted with increasing the aperture width. For the purpose of verifying the accuracy of the obtained results for the SE of an open spherical enclosure at resonance, the obtained field configurations and distributions inside a spherical enclosure of a small aperture are compared to those of the spherical cavity modes which have already been obtained analytically. Also, some of the results concerning the RCS of a spherical enclosure are compared to other published results.
Fast Computational Algoritm for EFIE Applied to Arbitrarily-Shaped Conducting Surfaces
Khalid Fawzy Ahmed Hussein
PIER , 2007, DOI: 10.2528/PIER06122502
Abstract: This work presents a fast computational algorithm that can be used as an alternative to the conventional surface-integral evaluation method included in the electric field integral equation (EFIE) technique when applied to a triangular-patch model for conducting surfaces of arbitrary-shape. Instead of evaluating the integrals by transformation to normalized area coordinates, they are evaluated directly in the Cartesien coordinates by dividing each triangular patch to a finite number of small triangles. In this way, a large number of double integrals is replaced by a smaller number of finite summations, which considerably reduces the time required to get the current distribution on the conducting surface without affecting the accuracy of the results. The proposed method is applied to flat and curved surfaces of different categories including open surfaces possessing edges, closed surfaces enclosing cavities and cavity-backed apertures. The accuracy of the proposed computations is realized in all of the above cases when the obtained results are compared with those obtained using the area coordinates method as well as when compared with some published results.
Accurate Representation of Excitation and Loading for Arbitrarily Shaped Antennas Composed of Conducting Surfaces in the Method of Moments
Khalid Fawzy Ahmed Hussein
PIER B , 2012, DOI: 10.2528/PIERB11100709
Abstract: In this work, a new method is introduced to model the excitation and loading for antennas composed of arbitrarily shaped conducting surfaces treated by the elctric field integral equation method described by Raw-Wilton-Glisson (RWG). Instead of using a single non-boundary edge to represent a zero-width exciting gap according to the conventional method, the proposed method uses either single or multiple pairs of facing boundary edges to form a real gap of arbitrary shape and width. The new method has many advantages over the conventional (zero-width) source/load representation considering the flexibility in shaping the gap to fit the antenna surface and the accuracy of the obtained results especially for the antenna input impedance and the input current distribution. The new method is described mathematically in detail. Modified basis functions are described for the gap source/load. Numerical results are obtained to investigate the dependence of the antenna input impedance and the current distribution along the gap length on the gap width, the geometrical shape of the gap and the surface segmentation resolution along the gap length.
Mechanism of Action of the Egyptian Garlic "Allium sativum" on Excitable Tissues
Aida Ahmed Hussein
Pakistan Journal of Biological Sciences , 2003,
Abstract: Garlic has been used for millennia in the traditional medicine practice of many cultures to treat cardiovascular and others disorders. In this study, mechanism of action of garlic on several excitable membranes have been discussed. three groups of isolated toads hearts were used to investigate the effect as well as the mechanism of garlic solution (4 g ml-1) on the physiological properties of the myocardium through the electrocardiogram (ECG) recordings. A significant decrease of the heart rate (negative chronotropism) accompanied by significant increase in the conduction time (positive dromotropism) were resulted following the garlic application and sustained 20 min. Several cases of heart block were recorded after 10 min from garlic perfusion. Application of atropine didn`t abolish the effect on the myocardium. Moreover, an increase of the ventricular voltage has been noticed after 10 min from the garlic application. The calcium-channel blocker verapamil apparently abolished the positive inotropic effect of the garlic. Smooth-muscle activity was studied before and after garlic application (4 g ml-1). An increase of the spontaneous contraction of rabbit-duodenum was established by garlic solution. Blockade the M3 muscarinic receptors of the smooth muscle by atropine sustained normal contraction. Perfusion of toad gastrocnemius-muscle/sciatic-nerve preparation with (4 g ml-1) garlic solution weakened the mechanical contraction of the muscle without recovery. Pretreatment with the nicotinic receptor antagonist gallamine sustained normal contraction of the skeletal muscle.
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