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Medhat M. Hassan,E.S. Fathy,Raouf O. Aly,S.E. Abdel Aal,Ahmed M. El-Masry 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5
Waste rubber (WR) powder was introduced in a two-roll mill in the presence of various ratios of curatives to develop sheets of devulcanized waste rubber (DWR). The selected product was investigated by FTIR, TGA and SEM. In a roll mill and hot press, styrene butadiene rubber (SBR) gum was differentially replaced by DWR feed ratios, and thereafter irradiated with gamma rays. The mechanical parameters of the developed blend were examined. Oil resistance and thermogravemetric behavior were discussed. Remarked improvement in the mechanical, thermal and physical parameters of SBR was generally determined by the incorporation of DWR and gamma irradiation.
Medhat M. Hassan,E.S. Fathy,Raouf O. Aly,S.E. Abdel Aal,Ahmed M. El-Masry 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5
Waste rubber (WR) powder was introduced in a two-roll mill in the presence of various ratios of curatives to develop sheets of devulcanized waste rubber (DWR). The product has been investigated by FTIR, TGA and SEM. A thermoplastic elastomer (TPE) was prepared by blending the obtained DWR with high density polyethylene (HDPE) at different feed ratios under conditions of gamma irradiation, 25, 50, 100, and 150 kGy. The mechanical parameters of the blend: tensile strength, elongation at break, and hardness (Shore D) were studied. In addition, blend characterization using FTIR spectra, gel fraction, TGA and SEM was discussed.
Medhat M. Hassan,Raouf O. Aly,Jehan A. Hasanen,El Sayed F. El Sayed 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.3
Composites of waste polyethylene (WPE), collected from municipal solid waste/recycled waste rubberpowder (RWRP) reactive compatibilizing agent, maleic anhydride (MA) and glass fiber (GF) up to 20 wt%,prepared by melting and irradiated with gamma-rays up to 150 kGy have been studied. Tensile strength(TS), elongation at break (Eb), elastic modulus, hardness, thermal and morphological parameters of theirradiated composites were investigated. The examined mechanical properties have been found toimprove largely with filler content. Interesting Eb behavior has been detected for the irradiatedcomposites loaded up to ~10 wt% GF and has been basically discussed in view of matrix crystallinity andmorphology. TGA thermograms of unirradiated composites revealed enhanced thermal stability thanthat reported for the blend whereas comparatively slight improvement has been demonstrated byirradiation. Whereby insignificant alteration in Tm values was observed by loading or irradiation, yetDHm maximum of 3.41 J/g, indicated for the 5 wt% GF irradiated composite with an integral dose of75 kGy, emphasizes the influence of the relatively moderate load and dose levels on matrix stability. Thephenomenon has been confirmed by the respective SEM micrographs.
Medhat M. Hassan,Nagwa A. Badway,Mona Y. Elnaggar,El-Sayed A. Hegazy 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4
Ground tire rubber (GRT) poses a challenging environmental, economical, and disposal problem in the world because of their crosslinked three-dimensional network structure. Waste rubber from end-of-life passenger car tires was successfully devulcanized by using mechanical–chemical process. The coupling of DR with PP in different proportion was investigated by FTIR, X-ray diffraction and SEM techniques. The mechanical and thermal behaviors of the blends composed of devulcanized rubber (DR) and high crystalline polypropylene (PP) in different proportions were studied. Evaluation of the mechanical and thermal properties of the developed blends, unirradiated and gamma irradiated, was carried out using tensile strength (Ts), elongation at break (Eb), hardness, TGA and DSC measurements.
MEDHAT SHARABI 한국원자력학회 2012 Nuclear Engineering and Technology Vol.44 No.7
The pressurized water reactor APR1400 adopts DVI (Direct Vessel Injection) for the emergency cooling water in the upper downcomer annulus. The International Standard Problem number 50 (ISP-50) was launched with the aim to investigate thermal hydraulic phenomena during a 50% DVI line break scenario with best estimate codes making use of the experimental data available from the ATLAS facility located at KAERI. The present work describes the calculation results obtained for the ISP-50 using the RELAP5/MOD3.3 system code. The work aims at validation and assessment of the code to reproduce the observed phenomena and investigate about its limitations to predict complicated mixing phenomena between the subcooled emergency cooling water and the two-phase flow in the downcomer. The obtained results show that the overall trends of the main test variables are well reproduced by the calculations. In particular, the pressure in the primary system show excellent agreement with the experiment. The loop seal clearance phenomenon was observed in the calculation and it was found to have an important influence on the transient progression. Moreover, the collapsed water levels in the core are accurately reproduced in the simulations. However, the drop in the downcomer level before the activation of the DVI from safety injection tanks was underestimated due to multi-dimensional phenomena in the downcomer that are not properly captured by one-dimensional simulations.
Extensions of Euler type II transformation and Saalsch[문자]tz's theorem
Medhat A. Rakha,Arjun K. Rathie 대한수학회 2011 대한수학회보 Vol.48 No.1
In this research paper, motivated by the extension of the Euler type I transformation obtained very recently by Rathie and Paris, the authors aim at presenting the extensions of Euler type II transformation. In addition to this, a natural extension of the classical Saalsch[문자]tz's summation theorem for the series _3F_2 has been investigated. Two interesting applications of the newly obtained extension of classical Saalsch[문자]tz's summation theorem are given.
Optimization of Water Pipe Network and Formulation of Pumping Rate
Medhat M. H. El-Zahar,Mohamed M. M. Amin 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7
Minimizing water delivery costs and increasing water supply dependability are the two keyobjectives in designing and operating of water distribution systems. An analytical solution forthe best pipe diameters of a water distribution pipe network was created in this study. The rawwater was collected from a water canal and transported to a treatment plant (WTP). Thecleansed water was pushed into the water distribution network via the pumping station. Thederivative approach was used in the optimization process, and the cost functions incorporating thevarious capital and operating expenses were used. The initial diameters were adjusted toreach the least-cost diameters. The study shows that the optimum design of a pipe network(PNW) achieves saving a total cost of about 12.3% after utilizing our unique method. Theoptimal pumping rate in the PNW can also be determined using an analytical approach thatconsiders the optimum value that occurs when the minor and friction losses in the entirenetwork are at their lowest. The analytical solution for the optimum pumping rate shows arigid value of optimum pumping rate (Qopt) which is 5296.32 m3/day. On comparativeestimates, this figure is very close to that of 5,300 m3/day interpreted from the graphicalsolution, with negligible deviation. The total cost and optimum pumping rate results for theanalyzed PNW example demonstrate the correctness of the analytical solutions, reliability, anddependability of the assumptions.
CERTAIN REDUCTION AND TRANSFORMATION FORMULAS FOR THE KAMPÉ DE FÉRIET FUNCTION
Rakha, Medhat A.,Rathie, Arjun K. Korean Mathematical Society 2022 대한수학회논문집 Vol.37 No.2
In 2014, Liu and Wang established a large number of interesting reduction, transformation and summation formulas for the Kampé de Fériet function. Inspired by the work, we aim to find further several transformation and reduction formulas for the Kampé de Fériet function. Theses formulas are mainly based on the formulas given by Liu and Wang [33].