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Search Results: 1 - 10 of 461660 matches for " A. A. Shaalan "
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Investigation and Comparison of 2.4 GHz Wearable Antennas on Three Textile Substrates and Its Performance Characteristics  [PDF]
M. I. Ahmed, M. F. Ahmed, A. A. Shaalan
Open Journal of Antennas and Propagation (OJAPr) , 2017, DOI: 10.4236/ojapr.2017.53009
Abstract:
In this paper, two different methods were used for investigating the RF characteristics of three types of textile materials. Goch, Jeans and Leather substrates were studied. A microstrip ring resonator method and DAK (Dielectric Assessment Kit) method were used. Bluetooth antennas were designed and fabricated using these substrates. The results were compared for the two methods. The bending effect of these antennas on its impedance characteristics due to human body movements was also studied. Finally, all antennas were simulated by CST simulator version 2016, fabricated using folded cupper and measured by Agilent 8719ES VNA. The measured results agree well with the simulated results.
Complementary Split Ring Resonator Loaded Substrate Integrated Waveguide Leaky Wave Antenna  [PDF]
Basma M. Yousef, Ahmed M. Attiya, A. A. Shaalan
Open Journal of Antennas and Propagation (OJAPr) , 2019, DOI: 10.4236/ojapr.2019.71001
Abstract: In this paper we present the design of a leaky wave antenna based on Substrate Integrated Waveguide (SIW) loaded by Complementary Split Ring resonator (CSRR). The proposed antenna is designed for 5G application with a center frequency around 28 GHz. The antenna is implemented on Roger RT/Duriod 5880. The loading CSRRs are designed to resonate at 28 GHz. The design is simulated by using both High-Frequency Simulation Software (HFSS) and Computer Simulation Technology (CST) for verification. Experimental measurements are also presented.
Reliability Evaluation of Renewable Energy Share in Power Systems  [PDF]
Zeyad A. Haidar, Abdullah M. Al-Shaalan
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.69006
Abstract: In this research, Renewable Energy (RE) represents the existing power systems with different levels. However, because of the intermittent nature of these sources, it is necessary to analyze systems’ reliability with different RE penetration levels. This work presented a simulation method for reliability evaluation of renewable penetrated power systems. Some reliability indices were proposed for the case of power systems with renewable power plants. The adopted approach used the historical data of renewable energy resources, mainly wind and solar to estimate the power that can be generated and compared with the demand to find the power mismatch. Therefore, this approach can be utilized to determine the penetration level that renewable energy can be shared, and it also helps the system operators in deciding the percentage of the generation that RE power plant can provide.
Study the Effects of Electromagnetic Band-Gap (EBG) Substrate on Two Patch Microstrip Antenna
Hanem F. Shaban;Hamdy A. Elmikaty;Abdelhamid A. Shaalan
PIER B , 2008, DOI: 10.2528/PIERB08081901
Abstract: Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, the effects of a two-dimensional electromagnetic bandgap (EBG) Structures on the performance of microstrip patch antenna arrays are investigated using the Ansoft High Frequency Selective Simulator (HFSS). A mushroom-like EBG structure is compared with 2-DEBG Structures. HFSS is employed to determine the effects of different Structures on two element microstrip patch antennas array. Two element microstrip patch antenna array on a uniform substrate suffer from strong mutual coupling due to the pronounced surface waves. Therefore, diverse forms of 2-DEBG Structures like: little number of holes, large number of holes, defect mode and different number of mushroom-patches columns structure are discussed. The two element microstrip patch antennas array placed on a defect in the electromagnetic (EBG) substrate that localizes the energy under the antennas. The excitation frequency of the two element microstrip patch antennas array near the resonance frequency of the defect mode can be used to control the coupling between antennas that are placed in an array. The mutual coupling improved by using large number of mushroom-patches columns structure.
Three-Dimensional Electric Field Analysis and Measurement Inside High Voltage Substations
Sayed A. Word,Samy M. Ghania,Essam M. Shaalan
International Journal of Electrical and Power Engineering , 2012, DOI: 10.3923/ijepe.2011.150.156
Abstract: The exposure to electric field now-a-days is an integral part in the design area of electrical power apparatus and systems. Moreover, the electric field produced by power lines, busbars and all high voltage equipments inside High Voltage (HV) substations is receiving more and more concerns to guarantee the life insurance of workers inside these substations. Therefore, the possible effect of the electric field exposure raises the question of how electric fields are created and what effects they may have. Therefore, monitoring the electric field inside Air Insulated Substation (AIS) and Gas Insulated Substation (GIS) is achieved in this study. This study not only depict the electric field distribution inside AIS using Charge Simulation Method (CSM) in three Dimensional (3D) and many Matlab M-files modeling programs developed by the researchers but also measured it inside AIS under 500 and 220 kV busbars and inside GIS nearby the 500, 220 and 66 kV busbars. The simulation results of AIS are compared with the measured values and the simulation results are matched with the measured values with very small tolerance about 1.4% for 220 kV model and about 4.4% for 500 kV model.
Wideband Partially-Covered Bowtie Antenna for Ground-Penetrating-Radars
Ghada Emam Atteia;Abdelhamid A. Shaalan;Khalid Fawzy Ahmed Hussein
PIER , 2007, DOI: 10.2528/PIER07030101
Abstract: In this paper, wide band transmitting and receiving antennas; each composed of a bowtie partially covered by an open conducting box; are proposed for ground-penetrating-radar (GPR) system. The inner walls of the conducting box are covered by a lossy coating which is composed of a number of layers with a conductivity profile designed to achieve better characteristics of the bowtie antenna. The Finite-Difference Time-Domain (FDTD) method is applied to simulate the radiating and receiving antennas, the buried target and the wave propagation in the lossy ground soil over the frequency band of operation. The performance of the proposed system is examined as regards the antenna characteristics and the buried target detectability. The impedance and voltage standing wave ratio (VSWR) of the partially covered bowtie antenna are presented over a wide frequency range. The capability of the proposed GPR system to detect targets buried in a ground soil is examined by investigating the change of the coupling between the transmitting and receiving antennas due to the presence of a buried target. The effect of the ground soil on the antenna characteristics is studied for some common types of real soils when the GPR system is placed at different heights above the ground surface.
Mosquitocidal activity of some volatile oils against Aedes caspius mosquitoes
R.S. Youssif & E.A. Shaalan
Journal of Vector Borne Diseases , 2011,
Abstract:
Simple Spectrophotometric Methods for Determination of Tenofovir Fumarate and Emtricitabine in Bulk Powder and in Tablets
Mohammad H. AbdelHay,Azza A. Gazy,Rasha A. Shaalan,Heba K. Ashour
Journal of Spectroscopy , 2013, DOI: 10.1155/2013/937409
Abstract: Two simple and selective methods were developed for the simultaneous determination of tenofovir fumarate (TEN) and emtricitabine (EMT) in combined tablets. The first method involves the application of first derivative spectrophotometry where the first derivative amplitudes were measured at 298.5?nm for determination of EMT in presence of TEN. The second method involves first derivative of ratio spectra spectrophotometry where the amplitudes at 251.5?nm have been used for quantitation of TEN in the presence of EMT. Different variables affecting each method were carefully investigated and optimized. Reliability and analytical performance of the proposed methods, including linearity, range, precision, accuracy, detection, and quantitation limits, were statistically validated. The methods were successfully applied for the determination of EMT and TEN in laboratory-prepared mixtures and in their combined tablets. 1. Introduction Antiviral drugs development has become a very active area in the last decade, especially with the challenges of AIDS, hepatitis, and avian and swine flu epidemics. The antiviral drugs are used in the treatment of viral infections. They may also be used to provide protection, usually for a brief period only, against infection. There is little evidence that these compounds affect latent or nonreplicating virus. Nonspecific symptomatic and supportive treatment is also important in the management of viral infections. Tenofovir disoproxil fumarate (TEN) is 9-[(R)-2 [[bis[[(isopropoxycarbonyl)oxy]methoxy] phosphinyl] methoxy] propyl] adenine fumarate [1] (Figure 1). It belongs to a class of antiretroviral drugs known as nucleotide analogue reverse transcriptase inhibitors (NRTIs), which block reverse transcriptase, an enzyme crucial to viral production in HIV-infected people [2, 3]. Figure 1: Structures of tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT). Emtricitabine (EMT), 4-amino-5-fluoro-1-[(2R,5S)-2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-1,2-dihydropyrimidin-2-one [1] (Figure 1), works by inhibiting reverse transcriptase enzyme that copies HIV RNA into new viral DNA. It can help lower the level of HIV in the patient’s body and can indirectly increase the number of immune system cells. EMT is indicated in combination with other antiretroviral agents for the treatment of HIV and HBV infection in adults [2, 3]. Being relatively recent drugs, TEN and EMT are not official in BP 2010 or USP 2011. TEN is formulated in binary mixture with the reverse transcriptase inhibitor emtricitabine (EMT) to prevent HIV from altering the
Monitoring Performance Degradation of Cerebellar Functions Using Computational Neuroscience Methods: Implications on Neurological Diseases
Robert A. Nawrocki, Majid Shaalan, Sean E. Shaheen, Nancy M. Lorenzon
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045581
Abstract: Neurodegeneration is a major cause of human disease. Within the cerebellum, neuronal degeneration and/or dysfunction has been associated with many diseases, including several forms of cerebellar ataxia, since normal cerebellar function is paramount for proper motor coordination, balance, and motor learning. The cerebellum represents a well-established neural circuit. Determining the effects of neuronal loss is of great importance for understanding the fundamental workings of the cerebellum and disease-associated dysfunctions. This paper presents computational modeling of cerebellar function in relation to neurodegeneration either affecting a specific cerebellar cell type, such as granule cells or Purkinje cells, or more generally affecting cerebellar cells and the implications on effects in relation to performance degradation throughout the progression of cell death. The results of the models show that the overall number of cells, as a percentage of the total cell number in the model, of a particular type and, primarily, their proximity to the circuit output, and not the neuronal convergence due to the relative number of cells of a particular type, is the main indicator of the gravity of the functional deficit caused by the degradation of that cell type. Specifically, the greater the percentage loss of neurons of a specific type and the closer proximity of those cells to the deep cerebellar neurons, the greater the deficit caused by the neuronal cell loss. These findings contribute to the understanding of the functional consequences of neurodegeneration and the functional importance of specific connectivity within a neuronal circuit.
First report of field evolved resistance to agrochemicals in dengue mosquito, Aedes albopictus (Diptera: Culicidae), from Pakistan
Hafiz Azhar Ali Khan, Waseem Akram, Khurram Shehzad, Essam A Shaalan
Parasites & Vectors , 2011, DOI: 10.1186/1756-3305-4-146
Abstract: For organophosphates and pyrethroids, the resistance ratios compared with susceptible Lab-PK were in the range of 157-266 fold for chlorpyrifos, 24-52 fold for profenofos, 41-71 fold for triazofos, and 15-26 fold for cypermethrin, 15-53 fold for deltamethrin and 21-58 fold for lambdacyhalothrin. The resistance ratios for carbamates and new insecticides were in the range of 13-22 fold for methomyl, 24-30 fold for thiodicarb, and 41-101 fold for indoxacarb, 14-27 fold for emamectin benzoate and 23-50 fold for spinosad. Pair wise comparisons of the log LC50s of insecticides revealed correlation among several insecticides, suggesting a possible cross resistance mechanism. Moreover, resistance remained stable across 3 years, suggesting field selection for general fitness had also taken place for various populations of Ae. albopictus.Moderate to high level of resistance to agrochemicals in Pakistani field populations of Ae. albopictus is reported here first time. The geographic extent of resistance is unknown but, if widespread, may lead to problems in future vector control.Dengue fever and dengue hemorrhagic fever (DF/DHF) are vector borne diseases of public health concerns in tropical and subtropical parts of the world [1], affecting millions of people annually [2]. The incidence of DF and DHF has increased cyclically in Pakistan since the first recognized outbreak in 1994 with Ae. albopictus (Skuse) as the core mosquito vector in this respect [3]. Currently, controlling this vector with insecticidal habitat spraying remains an important option to minimize the incidence of dengue fever [4], resulting in resurgence and development of insecticidal resistance.Insecticide resistance has become a limiting factor in the use of these compounds in chemical control of many insect pests. The exploration of more efficient toxic chemicals and other control tactics are necessary with the increasing world population and preservation of species diversity [5]. Frequent use of chemicals
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