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Search Results: 1 - 10 of 10845 matches for " Ahmed Samir "
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Orion Routing Protocol for Delay-Tolerant Networks
Samir Medjiah,Toufik Ahmed
Computer Science , 2012, DOI: 10.1109/icc.2011.5963362
Abstract: In this paper, we address the problem of efficient routing in delay tolerant network. We propose a new routing protocol dubbed as ORION. In ORION, only a single copy of a data packet is kept in the network and transmitted, contact by contact, towards the destination. The aim of the ORION routing protocol is twofold: on one hand, it enhances the delivery ratio in networks where an end-to-end path does not necessarily exist, and on the other hand, it minimizes the routing delay and the network overhead to achieve better performance. In ORION, nodes are aware of their neighborhood by the mean of actual and statistical estimation of new contacts. ORION makes use of autoregressive moving average (ARMA) stochastic processes for best contact prediction and geographical coordinates for optimal greedy data packet forwarding. Simulation results have demonstrated that ORION outperforms other existing DTN routing protocols such as PRoPHET in terms of end-to-end delay, packet delivery ratio, hop count and first packet arrival.
Effect of vitamin A and E on carbohydrate and lipid metabolism in diet-induced obese wistar rats  [PDF]
Mohamed Mohamed Soliman, Mohamed Mohamed Ahmed, Samir Ahmed El-Shazly, Tamer Ahmed Ismail, Hossam Fouad Attia, Ahmed Farag Elkirdasy
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.51002
Abstract:

In the present study, we investigated the biochemical alterations and gene expression of carbohydrate and lipid metabolism after oral administration of vitamin A and E for 2 months in diet-induced obese Wistar rats. Vitamin A and E administration reduced significantly the increase in body weight and food intake and normalized the alterations in lipid profiles in obese rats compared to normal rats. Moreover, both vitamins decreased the fat accumulation in liver tissues of obese rats. Finally, they up-regulated mRNA expression of Pyruvate Kinase (PK) and Glucose Transporter-2 (GLUT-2), and increased lipolysis and cholesterol metabolism through up-regulation of lipoprotein lipase (LPL), Sterol Responsible Element Binding Protein-1a (STREBP-1a) and STREBP-1c mRNA expression. In conclusion, vitamin A and E regulate gene expression of carbohydrate and lipid metabolism, and also ameliorate changes associated with obesity induced by high fat diet in Wistar rats.

Experimental Study of Electric and Spectroscopic Characteristics of Electric Discharge in LPG  [PDF]
Ahmed Abd Elradi, Nasser N. Morgan, Sobhy Ghalab, Mansour Elsabagh, Safwat Hassaballa, Ahmed Samir, Farouk F. Elakshar, Abdou A. Garamoon
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.515146
Abstract: Electric discharge has been carried out in LPG using DC high voltage (0.4 - 3 KV) at gas pressure in the range of 1 to 25 torr. The electric and spectroscopic characteristics of the discharge were studied at different discharge conditions. Deviations from Paschen’s law were observed as a result of the change of the distance between the two the electrodes. Two discharge modes, namely glow discharge and spark discharge modes, has been observed in the discharge current waveforms. The discharge current waveforms indicate a repetitive pulsed behaviour with frequencies of 5 kHz to 5 MHz depending upon the applied voltage and the gas pressure. The emitted spectra from the discharge are also studied near both the cathode and the anode using different electrode materials. Hα line and C2 Swan band system are observed, which confirms the conversion of LPG to hydrogen and carbon clusters.
Photoluminescence Coupled Raman Spectroscopy of Single-Layer Graphene Sheet  [PDF]
Mohamed G. Al- Khattib, Ahmed Samir, Nasser N. Morgan, Safwat Hassablla, M. A. Ahmed, Abdou A. Garamoon
Graphene (Graphene) , 2016, DOI: 10.4236/graphene.2016.54013
Abstract: We present a high quality single-layer graphene (SLG), triple layer graphene (TLG) and few layer graphene (FLG) sheets have been synthesized on cu substrate (metal catalyst) by direct current plasma enhanced chemical vapor deposition (DC-PECVD) at low growth temperature (from 600°C to 750°C). Mixture gas ratio, plasma electrical current and substrate temperature were investigated to determine the optimum condition of high quality single-layer graphene sheet synthesized. The characterization of graphene sheet was performed by X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), electron diffraction, Raman spectroscopy and photoluminescence (PL) spectrum. Photoluminescence and Raman result was coupled to investigation and evaluation of single-layer graphene sheet.
A Data Mining Approach for the Prediction of Hepatitis C Virus protease Cleavage Sites
Ahmed mohamed samir ali gamal eldin
International Journal of Advanced Computer Sciences and Applications , 2011,
Abstract: Summary: Several papers have been published about the prediction of hepatitis C virus (HCV) polyprotein cleavage sites, using symbolic and non-symbolic machine learning techniques. The published papers achieved different Levels of prediction accuracy. the achieved results depends on the used technique and the availability of adequate and accurate HCV polyprotein sequences with known cleavage sites. We tried here to achieve more accurate prediction results, and more Informative knowledge about the HCV protein cleavage sites using Decision tree algorithm. There are several factors that can affect the overall prediction accuracy. One of the most important factors is the availably of acceptable and accurate HCV polyproteins sequences with known cleavage sites. We collected latest accurate data sets to build the prediction model. Also we collected another dataset for the model testing. Motivation: Hepatitis C virus is a global health problem affecting a significant portion of the world’s population. The World Health Organization estimated that in1999; 170 million hepatitis C virus (HCV) carriers were present worldwide, with 3 to 4 million new cases per year. Several approaches have been performed to analyze HCV life cycle to find out the important factors of the viral replication process. HCV polyprotein processing by the viral protease has a vital role in the virus replication. The prediction of HCV protease cleavage sites can help the biologists in the design of suitable viral inhibitors. Results: The ease to use and to understand of the decision tree enabled us to create simple prediction model. We used here the latest accurate viral datasets. Decision tree achieved here acceptable prediction accuracy results. Also it generated informative knowledge about the cleavage process itself. These results can help the researchers in the development of effective viral inhibitors. Using decision tree to predict HCV protein cleavage sites achieved high prediction accuracy.
An Algorithm for the Numerical Evaluation of Certain Finite Part Integrals
Samir A. Ashour,Hany M. Ahmed
ISRN Applied Mathematics , 2011, DOI: 10.5402/2011/571583
Abstract:
AGEM: Adaptive Greedy-Compass Energy-aware Multipath Routing Protocol for WMSNs
Samir Medjiah,Toufik Ahmed,Francine Krief
Computer Science , 2012,
Abstract: This paper presents an Adaptive Greedy-compass Energy-aware Multipath protocol (AGEM), a novel routing protocol for wireless multimedia sensors networks (WMSNs). AGEM uses sensors node positions to make packet forwarding decisions. These decisions are made online, at each forwarding node, in such a way that there is no need for global network topology knowledge and maintenance. AGEM routing protocol performs load-balancing to minimize energy consumption among nodes using twofold policy: (1) smart greedy forwarding, based on adaptive compass and (2) walking back forwarding to avoid holes. Performance evaluations of AGEM compared to GPSR (Greedy Perimeter Stateless Routing) show that AGEM can: (a) maximize the network lifetime, (b) guarantee quality of service for video stream transmission, and (c) scale better on densely deployed wireless sensors network.
Streaming multimedia over WMSNs: an online multipath routing protocol
Samir Medjiah,Toufik Ahmed,Abolghasem Hamid Asgari
Computer Science , 2012,
Abstract: Routing is a challenge to Wireless Multimedia Sensor Networks (WMSNs) for supporting multimedia applications due to nodes' energy constraints and computational capabilities, and the ways sensor nodes obtain forwarding information. In this paper, we propose an online multipath routing protocol that uses nodes' positions to make forwarding decisions at each hop. Real-time decisions are made without any need to have the entire network topology knowledge. The protocol achieves load-balancing and minimises nodes' energy consumption by utilizing: (a) smart greedy forwarding scheme for selecting next hop, and (b) walking back forwarding scheme to bypass network holes. Performance comparisons of the proposed protocol (schemes) are made with TPGF and GPSR. The results show that our schemes: (a) maximise the overall network lifespan by not draining energy from some specific nodes, (b) provide QoS delivery for video streams by using best nodes along the route, and (c) scale better in high density WMSN.
GEAMS: a Greedy Energy-Aware Multipath Stream-based Routing Protocol for WMSNs
Samir Medjiah,Toufik Ahmed,Francine Krief
Computer Science , 2012, DOI: 10.1109/GIIS.2009.5307078
Abstract: Because sensor nodes operate on power limited batteries, sensor functionalities have to be designed carefully. In particular, designing energy-efficient packet forwarding is important to maximize the lifetime of the network and to minimize the power usage at each node. This paper presents a Geographic Energy-Aware Multipath Stream-based (GEAMS) routing protocol for WMSNs. GEAMS routing decisions are made online, at each forwarding node in such a way that there is no need to global topology knowledge and maintenance. GEAMS routing protocol performs load-balancing to minimize energy consumption among nodes using twofold policy: (1) smart greedy forwarding and (2) walking back forwarding. Performances evaluations of GEAMS show that it can maximize the network lifetime and guarantee quality of service for video stream transmission in WMSNs.
QoE assessment for SVC streaming in ENVISION
Abbas Bradai,Toufik Ahmed,Samir Medjiah
Computer Science , 2014,
Abstract: Scalable video coding has drawn great interest in content delivery in many multimedia services thanks to its capability to handle terminal heterogeneity and network conditions variation. In our previous work, and under the umbrella of ENVISION, we have proposed a playout smoothing mechanism to ensure the uniform delivery of the layered stream, by reducing the quality changes that the stream undergoes when adapting to changing network conditions. In this paper we study the resulting video quality, from the final user perception under different network conditions of loss and delays. For that we have adopted the Double Stimulus Impairment Scale (DSIS) method. The results show that the Mean Opinion Score for the smoothed video clips was higher under different network configuration. This confirms the effectiveness of the proposed smoothing mechanism.
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