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Search Results: 1 - 10 of 468906 matches for " Mohamed A. Sallih "
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Distances Scale Determination for a Planetary Nebula in Galactic Bulge  [PDF]
Sundus A. Abdullah, Nathera A. Ali, Mohamed A. Sallih
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32008
Abstract:

Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulge were calculated related to previous distances scales. The proposed distance scale was done by recalibrated the previous distance scale technique CKS/D82. This scale limited for nearby PN (D ≤ 3.5 kpc), so the surface fluxes less than other distance scales. With these criteria the results showed that the proposed distance scale is more accurate than other scales related to the observations for adopted sample of PN distances, also the limit of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45 > Rio (pc) > 0.03).

A Particle Swarm Optimization Algorithm for a 2-D Irregular Strip Packing Problem  [PDF]
Mohamed A. Shalaby, Mohamed Kashkoush
American Journal of Operations Research (AJOR) , 2013, DOI: 10.4236/ajor.2013.32024
Abstract:

Two-Dimensional Irregular Strip Packing Problem is a classical cutting/packing problem. The problem is to assign, a set of 2-D irregular-shaped items to a rectangular sheet. The width of the sheet is fixed, while its length is extendable and has to be minimized. A sequence-based approach is developed and tested. The approach involves two phases; optimization phase and placement phase. The optimization phase searches for the packing sequence that would lead to an optimal (or best) solution when translated to an actual pattern through the placement phase. A Particle Swarm Optimization algorithm is applied in this optimization phase. Regarding the placement phase, a combined algorithm based on traditional placement methods is developed. Competitive results are obtained, where the best solutions are found to be better than, or at least equal to, the best known solutions for 10 out of 31 benchmark data sets. A Statistical Design of Experiments and a random generator of test problems are also used to characterize the performance of the entire algorithm.

An Enhanced Genetic Programming Algorithm for Optimal Controller Design  [PDF]
Rami A. Maher, Mohamed J. Mohamed
Intelligent Control and Automation (ICA) , 2013, DOI: 10.4236/ica.2013.41013
Abstract:

This paper proposes a Genetic Programming based algorithm that can be used to design optimal controllers. The proposed algorithm will be named a Multiple Basis Function Genetic Programming (MBFGP). Herein, the main ideas concerning the initial population, the tree structure, genetic operations, and other proposed non-genetic operations are discussed in details. An optimization algorithm called numeric constant mutation is embedded to strengthen the search for the optimal solutions. The results of solving the optimal control for linear as well as nonlinear systems show the feasibility and effectiveness of the proposed MBFGP as compared to the optimal solutions which are based on numerical methods. Furthermore, this algorithm enriches the set of suboptimal state feedback controllers to include controllers that have product time-state terms.

Institutional Governance, Education and Growth  [PDF]
Mohamed Bouzahzah, Simplice A. Asongu, Mohamed Jellal
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.62015
Abstract: This study articulates the interaction among institutional governance, education and economic growth. Given the current pursuit of education policy reforms and knowledge economy around the world, it is of policy relevance to theoretically analyze the main mechanisms by which the macroeconomic impact of education on growth (and economic development) occurs. Our theoretical model demonstrates how incentives offered by the government affect human capital accumulation which ultimately engenders positive economic development externalities. We articulate two main channels through which education affects economic growth. The first channel highlights direct positive effect of educational quality on the incentive to accumulate human capital by individuals, which makes them more productive. The second channel appears in the explicit function of the economic growth rate. As a policy implication, we have shown that the growth rate depends on the rate of return on human capital or that this rate of return itself depends on the quality of governance, which further increases growth. As a result, institutional quality has a double dividend, which suggests considerable benefits to educational reforms.
Risk Factors for Stroke in Sulaimaniyah Iraqi Kurdistan Region-Iraq  [PDF]
Ahmed Saeed Mohamed, Mohamed A. M. Alshekhani
International Journal of Clinical Medicine (IJCM) , 2016, DOI: 10.4236/ijcm.2016.79070
Abstract: Background: Stroke is a frequent medical problem and a leading cause of death and disability worldwide. Several conditions and lifestyle factors have been associated with stroke. Aim: To evaluate risk factors in stroke patients in Sulaimani city. Results: 110 patients with stroke were included in this study, hypertension was found to be the most common risk factor in current study. Out of 110 cases, 83 (75.5%) were hypertensive. Peak stroke-prone age was (60 - 69) year for male, (70 - 79) year for female. We found a statistically significant relation between level of TSC, LDL with ischemic stroke (r = 0.4047, P < 0.0001) and (r = 0.4052 P < 0.0001) respectively. While there was a significant inverse relation between HDL and ischemic stroke (Correlation coefficient = ?0.4862, P < 0.0001). On the other hand, there was no significant relation between level of TG and ischemic stroke (r = 0.2403, P < 0.0114). Also correlation statistic between TSC/HDL, LDL/HDL and result of CT scan, showed that there is statistical significance correlation between infarction and value of atherogenic index, (r = 0.5301, P < 0.0001, r = 0.4990, P < 0.0001) respectively, but there is no correlation between haemorhage & the index. Conclusion: Hypertension is the leading risk factor of stroke. It is therefore essential to detect and treat hypertension at its outset. High value of atherogenic index mostly associated with ischemic stroke .while no relation found with haemorhagic stroke.
Role of Reversed Sural Artery Flap in Reconstruction of Lower Third of the Leg, Ankle and Foot Defects  [PDF]
Mohamed Elsayed Mohamed Mohamed, Belal A. Al Mobarak
Modern Plastic Surgery (MPS) , 2018, DOI: 10.4236/mps.2018.83007
Abstract: Introduction: Coverage of defects of the distal lower extremity and foot remains a challenging reconstructive prcedure. Free tissue transfer remains the standard for the management of these defects. However, there are some disadvantages like; longer operative times, bulky contour, and the need for highly skilled expertise. The reverse superficial sural artery flap (RSSAF) is a distally based fasciocutaneous or adipo-fascial flap that is used for coverage of defects that involve the distal third of the leg, ankle, and foot. A significant advantage of this flap is a constant blood supply that does not require sacrifice of a major artery. Methods: Twenty RSSAF flaps were harvested for reconstruction of different traumatic soft tissue defects of the lower third of leg, ankle and foot. Follow up for 6 months postoperative. Results: Twenty Patients; twelve males and eight females underwent reconstruction of different soft tissue defects over the foot and ankle using RSSAF. The overall complications occurred in 6 flaps; 4 minor and 2 major complications. The remaining 14 flaps passed an uneventful follow up. Conclusions: The reverse superficial sural artery flap RSSAF can be used as a reliable alternative to free tissue transfer in reconstruction of defects over the lower third of leg, ankle, and foot. Venous congestion is the major threat to the flap but its incidence can be minimized by wide pedicle, less kink of the flap, and keep the venae comitants around the artery.
Effect of static magnetic field on erythrocytes characterizations  [PDF]
Mohamed A. Elblbesy
Journal of Biomedical Science and Engineering (JBiSE) , 2010, DOI: 10.4236/jbise.2010.33040
Abstract: The interaction of static magnetic field (SMF) with living organisms is a rapidly growing field of investigation. Recently, exposure to moderate intensity SMFs (1 mT – 1 T) has attracted much attention for its various medical applications. This study was designed to show the microscopic effect of SMF on erythrocytes in vitro. For this purpose SMF system was constructed in my lab on basis of the idea of cell tracking velocimetry system. The changes in erythrocytes surface area, sphericity, and adhesion number for erythrocytes were calculated to quantify the effect of SMF on erythrocytes characterizations. The results showed that SMF increased erythrocytes surface area and reduced their sphericity. The adhesion number of erythrocytes under the influence of SMF showed the tendency of erythrocytes to adhere with each other. These findings indicate that more study on microscopic scales must be carried out in order to investigate the effect of SMF on erythrocytes.
A Solution for Fighting Spammer's Resources and Minimizing the Impact of Spam  [PDF]
Samir A. Elsagheer Mohamed
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.57051
Abstract: Spam or unsolicited emails constitute a major threat to the Internet, the corporations, and the end-users. Statistics show that about 70% - 80% of the emails are spam. There are several techniques that have been implemented to react to the spam on its arrival. These techniques consist in filtering the emails and placing them in the Junk or Spam folders of the users. Regardless of the accuracy of these techniques, they are all passive. In other words, they are like someone is hitting you and you are trying by all the means to protect yourself from these hits without fighting your opponent. As we know the proverbs \"The best defense is a good offense\" or \"Attack is the best form of defense\". Thus, we believe that attacking the spammers is the best way to minimize their impact. Spammers send millions of emails to the users for several reasons and usually they include some links or images that direct the user to some web pages or simply to track the users. The proposed idea of attacking the spammers is by building some software to collect these links from the Spam and Junk folders of the users. Then, the software periodically and actively visit these links and the subsequent redirect links as if a user clicks on these links or as if the user open the email containing the tracking link. If this software is used by millions of users (included in the major email providers), then this will act as a storm of Distributed Denial of Service attack on the spammers servers and there bandwidth will be completely consumed by this act. In this case, no human can visit their sites because they will be unavailable. In this paper, we describe this approach and show its effectiveness. In addition, we present an application we have developed that can be used for this reason.
Efficient Spam Filtering System Based on Smart Cooperative Subjective and Objective Methods  [PDF]
Samir A. Elsagheer Mohamed
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2013, DOI: 10.4236/ijcns.2013.62011
Abstract:

Most of the spam filtering techniques are based on objective methods such as the content filtering and DNS/reverse DNS checks. Recently, some cooperative subjective spam filtering techniques are proposed. Objective methods suffer from the false positive and false negative classification. Objective methods based on the content filtering are time consuming and resource demanding. They are inaccurate and require continuous update to cope with newly invented spammer’s tricks. On the other side, the existing subjective proposals have some drawbacks like the attacks from malicious users that make them unreliable and the privacy. In this paper, we propose an efficient spam filtering system that is based on a smart cooperative subjective technique for content filtering in addition to the fastest and the most reliable non-content-based objective methods. The system combines several applications. The first is a web-based system that we have developed based on the proposed technique. A server application having extra features suitable for the enterprises and closed work groups is a second part of the system. Another part is a set of standard web services that allow any existing email server or email client to interact with the system. It allows the email servers to query the system for email filtering. They can also allow the users via the mail user agents to participate in the subjective spam filtering problem.

Simple EPR/Alanine Dosimeter for Medical Application  [PDF]
Mohamed A. Morsy
Open Journal of Radiology (OJRad) , 2012, DOI: 10.4236/ojrad.2012.24022
Abstract: Linac x-ray and direct gamma irradiation sources were used in this study to irradiate simple polycrystalline alanine- in-glass (AiG) dosimeters with low-doses, typical for medical therapy, and high-doses, typical for syringes’ sterilization processe, respectively. The generated “stable” alanine radicals were quantitatively investigated by electron paramagnetic resonance (EPR) spectroscopy in the presence of an external standard reference (Mn2+/MgO) to correct for spec- trometer sensitivity variation. The results indicated that the de-amination of L-alanine is the main reaction to form the “stable” radical and the AiG-dosimeter gives comparable sensitivity for both low and high radiation doses. Moreover, a linear EPR-radiation dose response is observed over a very wide range, from 0 to 50 kGy, which is contrary to what has been reported by Bruker BioSpin using alanine’s pellet. This linear response and the well-known doses’ cumulative characteristics of alanine are in favor of the use of this simple dosimeter in ample medical applications, particularly the conventional radiotherapy treatment per patient.
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