Ahmed Radwan | Cairo University (original) (raw)

Papers by Ahmed Radwan

International Journal of Cloud Computing, 2011

MapReduce is a parallel programming model that is proven to scale. However, using the low-level M... more MapReduce is a parallel programming model that is proven to scale. However, using the low-level MapReduce for general data processing tasks poses the problem of developing, maintaining and reusing custom low-level user code. Several frameworks have emerged ...

International Journal of Web Information Systems, 2010

Purpose – Information retrieval (IR) and feedback in Extensible Markup Language (XML) are rather ... more Purpose – Information retrieval (IR) and feedback in Extensible Markup Language (XML) are rather new fields for researchers; natural questions arise, such as: how good are the feedback algorithms in XML IR? Can they be evaluated with standard evaluation tools? Even though some evaluation methods have been proposed in the literature it is still not clear yet which of them

International Journal of Phytoremediation, 2015

In this research, dead leaves of a common ornamental plant, Dracaena draca known also as dragon t... more In this research, dead leaves of a common ornamental plant, Dracaena draca known also as dragon tree was used as a biosorbent for the removal of Cadmium (Cd(2+)) from aqueous solutions using a full 2(3) factorial experimental design. Three factors were investigated at two different levels, metal ion concentration (X=10 and 100ppm), hydrogen ion concentration (pH=2 and 7) and biomass dose (BD=0.1 and 0.5g). Experiments were carried out in duplicates with 50 ml of Cd(2+) solutions at room temperature. When comparing observed values (experimental) with calculated values (model), they were set closely together that allowed suggesting a normal distribution where (R(2) =0.9938). A characterization of the biosorbent was done by pHzpc and SEM-EDAX. Results also showed that the most significant effect for Cd(2+) biosorption was ascribed to (X). The interaction effects of (pH BD) and (X pH) were found to have significant influence on Cd(2+) removal efficiency. The highest Cd(2+) removal percentage attained by 79.60% at X=10 ppm, pH=7 and BD=0.5g. The reusability of the biosorbent was tested in three desorption cycles and the regeneration efficiency was above 99.7%.

Applied Water Science, 2015

ABSTRACT The biosorption efficiency of Cd 2? using rice straw was investigated at room temperatur... more ABSTRACT The biosorption efficiency of Cd 2? using rice straw was investigated at room temperature (25 ± 4 °C), contact time (2 h) and agitation rate (5 Hz). Experiments studied the effect of three factors, biosorbent dose BD (0.1 and 0.5 g/L), pH (2 and 7) and initial Cd 2? concentration X (10 and 100 mg/L) at two levels ''low'' and ''high''. Results showed that, a variation in X from high to low revealed 31 % increase in the Cd 2? biosorption. However, a discrepancy in pH and BD from low to high achieved 28.60 and 23.61 % increase in the removal of Cd 2? , respectively. From 2 3 factorial design, the effects of BD, pH and X achieved p value equals to 0.2248, 0.1881 and 0.1742, respectively, indicating that the influences are in the order X [ pH [ BD. Similarly, an adaptive neuro-fuzzy inference system indicated that X is the most influential with training and checking errors of 10.87 and 17.94, respectively. This trend was followed by ''pH'' with training error (15.80) and checking error (17.39), after that BD with training error (16.09) and checking error (16.29). A feed-forward back-propagation neural network with a configuration 3-6-1 achieved correlation (R) of 0.99 (training), 0.82 (validation) and 0.97 (testing). Thus, the proposed network is capable of predicting Cd 2? biosorp-tion with high accuracy, while the most significant variable was X.

BMJ open, Jan 5, 2015

To assess the prevalence of awareness and use of massive open online courses (MOOCs) among medica... more To assess the prevalence of awareness and use of massive open online courses (MOOCs) among medical undergraduates in Egypt as a developing country, as well as identifying the limitations and satisfaction of using these courses. A multicentre, cross-sectional study using a web-based, pilot-tested and self-administered questionnaire. Ten out of 19 randomly selected medical schools in Egypt. 2700 undergraduate medical students were randomly selected, with an equal allocation of participants in each university and each study year. Primary outcome measures were the percentages of students who knew about MOOCs, students who enrolled and students who obtained a certificate. Secondary outcome measures included the limitations and satisfaction of using MOOCs through five-point Likert scale questions. Of 2527 eligible students, 2106 completed the questionnaire (response rate 83.3%). Of these students, 456 (21.7%) knew the term MOOCs or websites providing these courses. Out of the latter, 136 ...

Acta Adriatica, 2007

Two winter sets of hydrographic data representing warm and cold winters for 1989 and 1990 respect... more Two winter sets of hydrographic data representing warm and cold winters for 1989 and 1990 respectively were used to study the characteristics of Egyptian Mediterranean water masses. The classification was based on the variations of air and surface water temperatures. Four water masses were observed during winter; (i) the surface water mass of temperature 17-19 °C, salinity maximum 39.0->39.2 occupies the upper 200 m layer, (ii) the Levantine intermediate water mass of temperature 15-17 °C and salinity 38.8-39.0 occupies depths between 200 and 400 m,(iii) a mid-depth water mass lies between 400 an 800 m of temperature 14-15 °C and salinity range 38.75-38 and (iv) the deep water mass of potential temperature range 13.3-13.5 °C, salinity 38.6-38.75 and density ~29.1 σ t . By analyzing the water temperature and salinity distributions, we found that the average surface water temperature are 18.88 °C and 16.73 °C during the warm and cold winters, respectively with an average difference of 2.1 °C. The difference reached the maximum value of 2.32 °C at 50 m depth. It decreases with increasing depth to reach 0.12 °C at 200 m depth. At the depth of 250-500 m, the difference was negative and varied between -0.42 and -0.17 °C. The difference of average salinity at the surface was about 0.07 and decreased to reach 0.03 at 50 m depth. At depth of 100 m and down to 500 m, the difference values were negative and varied between -0.03 and -0.09.

Astrophysics and Space Science, 1990

The magnetodynamic (in) stability of a conducting fluid cylinder subject to the capillarity and e... more The magnetodynamic (in) stability of a conducting fluid cylinder subject to the capillarity and electromagnetic forces has been developed. The cylinder is pervaded by a uniform magnetic field but embedded in the Lundquist force-free varying field that allows for ...

ABSTRACT The prediction of hepatitis C virus (HCV) is a significant and tedious task in medicine.... more ABSTRACT The prediction of hepatitis C virus (HCV) is a significant and tedious task in medicine. The healthcare environment is generally perceived as being &#39;information rich&#39; yet &#39;knowledge poor&#39;. There is a wealth of data available within the healthcare system. However, there is a lack of effective analysis tools to discover hidden relationships and trends in data. Knowledge discovery and data mining have found numerous applications in business and scientific domain. Valuable knowledge can be discovered from application of data mining techniques in healthcare system. Using medical profile such as age, sex, residence and (ALT, AST) enzyme blood tests it can predict the likelihood of patients getting HCV infection. It enables significant knowledge, e.g. patterns, relationships between medical factors related to HCV, to be established. It can serve a training tool to train nurses and medical students to diagnose patients infected with HCV. This paper analyses the performance of various classification function techniques in data mining for predicting the infection with HCV from the HCV data set. These Techniques are Decision Trees, Naïve Bayes and Neural Network. Results show that each technique has its unique strength in realizing the objectives of the defined mining goals. Also the performance of three data mining techniques is compared using three data sets of different size.

Journal of the Physical Society of Japan, Apr 15, 1989

Page 1. Journal of the Physical Society of Japan Vol. 58, No. 4, April, 1989, pp. 1225-1227 Insta... more Page 1. Journal of the Physical Society of Japan Vol. 58, No. 4, April, 1989, pp. 1225-1227 Instability of a Hollow Jet with Effects of Surface Tension and Fluid Inertia Ahmed E. RADWAN Department of Mathematics, Faculty of ...

Applied Mathematics and Computation, Sep 5, 2003

The instability of self-gravitating magnetized triple superposed fluids layers of different densi... more The instability of self-gravitating magnetized triple superposed fluids layers of different densities has been regarded crucial to the origin of the breaking-up of the fluids layers resulting in the appearance of condensation within astronomical bodies. This phenomenon also is of interest, academically and, during the geological drillings in the crust of the earth as we have superposed gas–oil layers-mixture fluids.The

Page 1. AbstractThis study investigates the use of genetic algorithms in information retrieval. ... more Page 1. AbstractThis study investigates the use of genetic algorithms in information retrieval. The method is shown to be applicable to three well-known documents collections, where more relevant documents are presented to users in the genetic modification. ...

Page 1. Qatar Univ . Sci. J . (2007), 27 : 1 - 9 Algebraic Approach to Formal Microstructure Shea... more Page 1. Qatar Univ . Sci. J . (2007), 27 : 1 - 9 Algebraic Approach to Formal Microstructure Sheaves and Formal Quantum Sheaves Over Projective Schemes AE Rad wan KA Hashem Department of Mathematics Department ...

Il Nuovo Cimento B, 2001

The self-gravitating instability of a compressible-inviscid fluid cylinder immersed into a self-g... more The self-gravitating instability of a compressible-inviscid fluid cylinder immersed into a self-gravitating tenuous medium of negligible motion is developed. The stability criterion is derived based on the linear perturbation technique. Some previous reported works are recovered. The effect of different factors on the fluid cylinder instability is discussed. The compressibility has a tendency for a stabilizing the model in particular as the sound speed aaa is very large in the stable domains 1.0233928leqx<infty1.0233928\leq x<\infty1.0233928leqx<infty but comparatively small in the unstable domains 0<x<1.02339280<x<1.02339280<x<1.0233928 where x=kR0x=k R_{_{0}}x=kR0 is the dimensionless longitudinal wavenumber with kkk is the axial wavenumber and R0R_{_{0}}R0 is the radius of the cylinder. In the absence of the compressibility factor the unstable domain is found to be 0<x<1.06780<x<1.06780<x<1.0678.

Nuovo Cimento B Serie, 2002

Journal of the Physical Society of Japan, Feb 1, 1988

Magnetohydrodynamic stability of an infinite self-gravitating, inviscid and perfectly conducting ... more Magnetohydrodynamic stability of an infinite self-gravitating, inviscid and perfectly conducting medium with streams of variable velocity distribution is investigated for general wave propagation. The streaming motion has a destabilizing influence on the medium. The magnetic field exerts a strong stabilizing effect which causes the bending of the magnetic force lines. The medium is unstable only for certain values of the wave number and stable for all other values. The instability Jean's criterion of a static medium is unaffected by the inclusion of the magnetic field effects, even if it is with a uniform streaming.

Nuovo Cimento B Serie, Dec 1, 1999

The magnetohydrodynamic MHD instability of a dissipative compressible rotating self-gravitating f... more The magnetohydrodynamic MHD instability of a dissipative compressible rotating self-gravitating fluid medium with general rotation and propagation has been investigated. The required basic equations for describing the present problem are formulated, linearized and solved, with excluding the singular solutions, based on the linear perturbation technique. Appropriate boundary conditions are applied with the aim of determining the unknowns of integrations and finally the desired dispersion relation has been derived in its general form. A lot of dispersion relations associated with physical problems are obtained from the present general one under appropriate and suitable choices.

The Extensible Markup Language (XML) technology, with its self-describing and extensible tags, is... more The Extensible Markup Language (XML) technology, with its self-describing and extensible tags, is significantly contributing to the next generation of semantic web. The present search techniques used for HTML and text documents are not efficient to retrieve relevant XML documents. Terms occurring in some places should have a greater influence than that elsewhere. An occurrence in an abstract may be more important than an occurrence in the body text. Although this observation is not new, there remains the issue of finding good weights for each structure. Vector space ranking are extended to include structure weighting.

J Phys Soc Jpn, 1990

Page 1. Journal of the Physical Society of Japan Vol. 59, No. 2, February, 1990, pp. 537-543 Magn... more Page 1. Journal of the Physical Society of Japan Vol. 59, No. 2, February, 1990, pp. 537-543 Magnetohydrodynamic Stability of a Streaming Hollow Jet Ahmed E. Rad wan Department of Mathematics, Faculty of Science, Ain ...