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Search Results: 1 - 10 of 9352 matches for " Ahmed Bahgat "
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A Framework for Translating a High Level Security Policy into Low Level Security Mechanisms
Ahmed A. Hassan , Waleed M. Bahgat
Journal of Electrical Engineering , 2010, DOI: 10.2478/v10187-010-0003-x
Abstract: Security policies have different components; firewall, active directory, and IDS are some examples of these components. Enforcement of network security policies to low level security mechanisms faces some essential difficulties. Consistency, verification, and maintenance are the major ones of these difficulties. One approach to overcome these difficulties is to automate the process of translation of high level security policy into low level security mechanisms. This paper introduces a framework of an automation process that translates a high level security policy into low level security mechanisms. The framework is described in terms of three phases; in the first phase all network assets are categorized according to their roles in the network security and relations between them are identified to constitute the network security model. This proposed model is based on organization based access control (OrBAC). However, the proposed model extend the OrBAC model to include not only access control policy but also some other administrative security policies like auditing policy. Besides, the proposed model enables matching of each rule of the high level security policy with the corresponding ones of the low level security policy. Through the second phase of the proposed framework, the high level security policy is mapped into the network security model. The second phase could be considered as a translation of the high level security policy into an intermediate model level. Finally, the intermediate model level is translated automatically into low level security mechanism. The paper illustrates the applicability of proposed approach through an application example.
Effect of Coconut Oil Administration on Some Hemostatic Changes Associated with Obesity in Rats
Fatma Ahmed Mohamed, Nehal Mohammad Bahgat
Egyptian Journal of Hospital Medicine , 2009,
Abstract: In the last few decades, coconut oil was claimed to have some beneficial health effects, attributed mainly to its medium chain triglycerides. It was, thus, intriguing to investigate the potential benefit of coconut oil in alleviating the prothrombotic tendency often encountered in obese individuals. The present study was carried out on 44 rats, of both sexes, aged 10 days at the start of the study. 31 out of 44 rats were offered high caloric diet (the cafeteria diet) for induction of obesity. Rats were allocated into the following groups: Group1: Control rats (C) (n=13 rats), comprising rats fed on the standard chow diet all-over the study period (24 weeks). Group2: Cafeteria diet-fed rats (Caf) (n=16 rats), comprising rats fed on cafeteria diet until the end of the study period and Group3: Cafeteria diet/coconut oil-fed rats (Caf/Coco) (n=15 rats), comprising rats fed on cafeteria diet with coconut oil starting from the 16th week till the end of the study period. At the end of the study, the BMI was assessed in the 3 studied groups and blood samples were collected for determination of platelet count and aggregation, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrin degradation products (FDPs), and plasma lipid profile. The encountered results revealed that the mean BMI of the cafeteria diet-fed rats was significantly higher than the BMI of control rats, and that the mean BMI of rats receiving cafeteria/coconut oil diet for 9 weeks was significantly decreased compared to their matched caf group. The PT, APTT and platelet count were all non significantly different in the three studied groups. Platelet aggregation, on the other hand, was significantly increased in the caf group compared to the control group, and significantly decreased in the caf/coco group compared to both the caf group and the control group. The plasma FDPs levels were not significantly different in the 3 studied groups. The lipid profile was insignificantly different in the 3 studied groups except in the caf/coco group which revealed a significant elevation of total cholesterol and HDL-c compared to caf group. The present findings, thus, point to the possible beneficial effect of coconut oil feeding on obesity - induced enhanced platelet aggregation.
Parameter Identification of Induction Motor Using Modified Particle Swarm Optimization Algorithm
Hassan M Emara,Wesam Elshamy,Ahmed Bahgat
Computer Science , 2013,
Abstract: This paper presents a new technique for induction motor parameter identification. The proposed technique is based on a simple startup test using a standard V/F inverter. The recorded startup currents are compared to that obtained by simulation of an induction motor model. A Modified PSO optimization is used to find out the best model parameter that minimizes the sum square error between the measured and the simulated currents. The performance of the modified PSO is compared with other optimization methods including line search, conventional PSO and Genetic Algorithms. Simulation results demonstrate the ability of the proposed technique to capture the true values of the machine parameters and the superiority of the results obtained using the modified PSO over other optimization techniques.
Polyploidy and Discontinuous Heredity Effect on Evolutionary Multi-Objective Optimization
Wesam Elshamy,Hassan M Emara,Ahmed Bahgat
Computer Science , 2013,
Abstract: This paper examines the effect of mimicking discontinuous heredity caused by carrying more than one chromosome in some living organisms cells in Evolutionary Multi-Objective Optimization algorithms. In this representation, the phenotype may not fully reflect the genotype. By doing so we are mimicking living organisms inheritance mechanism, where traits may be silently carried for many generations to reappear later. Representations with different number of chromosomes in each solution vector are tested on different benchmark problems with high number of decision variables and objectives. A comparison with Non-Dominated Sorting Genetic Algorithm-II is done on all problems.
Clubs-based Particle Swarm Optimization
Wesam Elshamy,Hassan M Emara,Ahmed Bahgat
Computer Science , 2013,
Abstract: This paper introduces a new dynamic neighborhood network for particle swarm optimization. In the proposed Clubs-based Particle Swarm Optimization (C-PSO) algorithm, each particle initially joins a default number of what we call 'clubs'. Each particle is affected by its own experience and the experience of the best performing member of the clubs it is a member of. Clubs membership is dynamic, where the worst performing particles socialize more by joining more clubs to learn from other particles and the best performing particles are made to socialize less by leaving clubs to reduce their strong influence on other members. Particles return gradually to default membership level when they stop showing extreme performance. Inertia weights of swarm members are made random within a predefined range. This proposed dynamic neighborhood algorithm is compared with other two algorithms having static neighborhood topologies on a set of classic benchmark problems. The results showed superior performance for C-PSO regarding escaping local optima and convergence speed.
Age and Heat Stress Related Changes in Monoamine Contents and Cholinesterase Activity in Some Central Nervous System Regions of Albino Rat Newborns
Osama M. Ahmed,M. Bahgat,R.G. Ahmed
International Journal of Zoological Research , 2007,
Abstract: The normal monoamine [norepinephrine (NE), epinephrine (E), dopamine (DA) and serotonin (5-HT)] contents and cholinestrase (chE) activity were significantly and gradually increased with age progress between postnatal days 7 and 21 in cerebrum, cerebellum, medulla oblongata and spinal cord of rat newborns. The daily exposure of the newborns to 401C for 2 h induced deteriorated effects and the withdrawal period of 7 days failed to return these altered variables to normal levels. On the other hand, the high temperature exerted its most potent decreased effect on monoamine contents at 21 days old. This decrease may be attributed to the elevated activity of monoamine oxidase and/or the decreased activity of the key enzymes responsible for monoamine synthesis. The chE activity exhibited different effects in the tested CNS regions as a result of high temperature exposure; the enzyme activity was decreased markedly at days 7, 14 and 21 in cerebellum and medulla oblongata and lowered only at days 7 and 14 in cerebrum and at day 14 in spinal cord. The subsequent withdrawal for 7 days beyond day 21 produced marked weakening of effect of high temperature exposure on monoamine contents in all examined CNS regions except NE and 5-HT contents in cerebellum and DA level in medulla oblongata. In spite of this attenuation, the values recorded in the withdrawal group were still significantly lower than the normal levels. On the other hand, the chE activity became more deleteriously affected at day 28 in the treated CNS regions except in the medulla oblongata where it was profoundly ameliorated after the withdrawal period.
Electrical, magnetic, and corrosion resistance properties of TiO2 nanotubes filled with NiFe2O4 quantum dots and Ni–Fe nanoalloy
Mohamed Bahgat,Ahmed A. Farghali,Ahmed F. Moustafa,Mohamed H. Khedr,Mohassab Y. Mohassab-Ahmed
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0122-8
Abstract: This work was carried out as an integral part of a project aiming to improve the catalytic, electrical, magnetic, and mechanical properties of synthesized TiO2NTs filled with metal ferrites. TiO2 nanotubes in the anatase-phase (TiO2NTs) were prepared using a hydrothermal method followed by ion exchange and phase transformation. The obtained TiO2NTs were filled with NiFe2O4 quantum dots (QDs) and then reacted at 600 °C in a reducing atmosphere to produce TiO2NTs filled with Ni–Fe nanoalloy. The effect of the TiO2NTs’ coating on the dissolution rate of Ni–Fe nanoalloy in 0.5 M HCl solution was monitored chemically using a weight-loss technique that was performed at different temperatures. The TiO2NTs’ coating exhibited high protective performance and amazing corrosion resistance. The magnetic properties of the TiO2NTs filled with NiFe2O4 QDs and Ni–Fe nanoalloy compacts were analyzed by a vibrating sample magnetometer. The electrical conductivity-temperature dependence of anatase TiO2NTs, anatase TiO2NTs filled with NiFe2O4 quantum dots, anatase TiO2NTs filled with Ni–Fe nanoalloy, and NiFe2O4 was measured in the temperature range of 25–850 °C. The conductivity increased with temperature, indicating the semiconductor-like nature of the sample. During cooling, the conductivity retains values higher than that obtained during heating.
Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite
Mohamed Bahgat,Ahmed Ali Farghali,Waleed El Rouby,Mohamed Khedr,Mohassab Y. Mohassab-Ahmed
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0127-3
Abstract: This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (ΔG°), enthalpy (ΔH°), entropy (ΔS°), and the activation energy (E a) were determined. The ΔH°, ΔG° and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.
Hybrid Compression Encryption Technique for Securing SMS
Ahmed M Mahfouz,Awny A. Ahmed,Bahgat A. Abdel-latef,Tarek
International Journal of Computer Science and Security , 2010,
Abstract: Mobile communication devices have become popular tools for gathering and disseminating information and data. When sensitive information is exchanged using SMS, it is crucial to protect the content from eavesdroppers as well as ensuring that the message is sent by a legitimate sender. Using an encryption technique to secure SMS data increases its length and accordingly the cost of sending it. This paper provides a hybrid compression encryption technique to secure the SMS data. The proposed technique compresses the SMS to reduce its length, then encrypts it using RSA algorithm. A signature is added to the encrypted SMS for signing it to differentiate it from other SMS messages in SMSINBOX. The experimental results which are based on Symbian OS show that the proposed technique guarantees SMS data security without increasing its size.
Diversity of Bacterial Communities in Contrasting Aquatic Environments: Lake Timsah, Egypt
Magdy Bahgat
Microbiology Insights , 2012, DOI: 10.4137/MBI.S6948
Abstract: Effect of pollution on diversity of attached and free-living bacteria in two contrasting stations, namely, Suez Canal and outlet of West Lagoon to Lake Timsah was investigated. Bacillus was the most abundant genus especially in West Lagoon station where higher organic agricultural and municipal loads was discharged. Bacterial species richness differed among water depths and was higher in subsurface samples. In Suez Canal more Gram negative populations were isolated. The possible influences of pollution in the West Lagoon station on the bacterial community composition were discussed.
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