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Ismail A.S.,AMA International University Bahrain | Andeng P.B.,Egyptian Petroleum Research Institute | El-Meligi A.A.,National Research Center of Egypt
Journal of Corrosion Science and Engineering | Year: 2014

The present research work investigated the corrosion behaviour of casted pure aluminium metal and aluminium-copper alloy after running weight loss tests in different concentration ratios of H2SO4 media at RT and 50°C, respectively. Corrosion penetration rate was determined within interval immersion periods of 5 hours. At RT, it was observed that pure aluminium samples have low corrosion resistance in concentrations 10% and 15% of H2SO4 solutions. Moreover, corrosion rate increases slightly with increasing concentration of H2SO4 media and the attack was more significant at 50°C. Al-Cu alloy show decreasing of weight loss and more corrosion resistance in both ratios. The corrosion penetration rate of Al samples increases in the order Al-Cu < Al as a result of the formation of thin protective aluminium-copper oxide films. The visual observations shown that there is a streaking and grooves of both samples correlated directly with the increased exposure period in the acidic medium but in case of Al-Cu alloy there are a several horizontal fine darkened pits grew along the surface. © 2014 University of Manchester and the authors. Source

Abdel-Hameed S.A.M.,National Research Center of Egypt | Margha F.H.,National Research Center of Egypt | El-Meligi A.A.,National Research Center of Egypt | El-Meligi A.A.,AMA International University Bahrain
International Journal of Energy Research | Year: 2014

SUMMARY: Crednerite glass-ceramic material (CuMnO2) has been investigated for the first time as a hydrogen storage candidate. The average gravimetric capacity is about 16g H2/kg and about 50g H2/kg of CuMnO2 at 473 and 573K respectively under a pressure up to 20bars. The hydrogen adsorbed capacity (weight percent) of CuMnO2 increased with increasing temperature. The material doesn't release hydrogen during desorption cycle revealing storage of hydrogen in the prepared material. X-ray diffraction patterns reveal a structure corresponding to Cu2O, CuMnO2, and traces of CuO and SiO2 phases. X-ray diffraction patterns exhibit a reduction of copper ions to copper metal beside cristobalite and traces from manganese oxide phase after exposing to H2 at 80 and 573K. This reduction of Cu ions into Cu metal may explain the irreversibility of hydrogen adsorption process. Thermal stability detected by differential scanning calorimetry and thermal gravimetric analysis shows decomposition temperature up to ~473K followed by gain of weight till 1173K then another decomposition till 1273K. © 2013 John Wiley & Sons, Ltd. Source

Sharef Z.T.,AMA International University Bahrain | Alaradi A.E.,University of Technology Malaysia | Sharef B.T.,National University of Malaysia
Proceedings - 2012 4th International Conference on Computational Intelligence, Communication Systems and Networks, CICSyN 2012 | Year: 2012

In this paper, a detailed link level simulation has been studied and optimized to investigate the physical layer performance of Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16e over AWGN and multipath Rayleigh fading channels, in which ITU-Reference channel models have been used. Two 802.16e based OFDMA transceivers have been designed by using MATLAB Simulink, the first one doesn't support channel estimation whereas the second does. Moreover, the effect of fading channel, Doppler shift and cyclic prefix on the system design performance has been analyzed and investigated. The bit error rate (BER) vs. bit energy-to-noise density ratio (Eb/No) curves was used to evaluate and compare the performance of QPSK modulation technique. The outcomes of simulation results clarified how the use of channel estimation improves the system performance, whereas obviously, the investigated system suffers from severe performance degradation and high probability of error whenever channel estimation is not applied. © 2012 IEEE. Source

Ismail A.S.,AMA International University Bahrain | Ismail A.S.,Egyptian Petroleum Research Institute
Silicon | Year: 2016

The present paper discussed the corrosion behavior of aluminum-silicon-copper-manganese alloy compared with the pure aluminum metal which already reported. Weight loss tests carried out in concentration ratios of H 2SO4 solutions at different temperatures. As a part of the study, corrosion penetration rate determined within interval immersion periods of 5 h. At room temperature, it is observed that aluminum alloys shows decreasing of weight loss and more corrosion resistance in concentrations 10 and 15 % of H 2SO4 solutions compared with the obtained results of pure Al metal. Moreover, corrosion rate increases slightly with increasing concentration of H 2SO4media and the attack is more significant at 50 ∘C. Also, the corrosion penetration rate of Al alloy decreased in the same trend as a result of the formation of thin protective multi oxide films of aluminum, silicon, copper and manganese. Furthermore, the microscopic analysis showed that there is fine pits appeared on the Al alloy surface correlated directly with the increased exposure period in the acidic solution whereas in case of pure Al metal there were a many horizontal streaks formed along the surface. © 2015, Springer Science+Business Media Dordrecht. Source

Gonzales T.T.,Nagasaki University | Gonzales T.T.,Southeast Asian Fisheries Development Center | Gonzales T.T.,AMA International University Bahrain | Katoh M.,Seikai National Fisheries Research Institute | And 3 more authors.
Journal of Morphology | Year: 2011

To illustrate vascular modification accompanying transition from aquatic to amphibious life in gobies, we investigated the respiratory vasculatures of the gills and the bucco-opercular cavities in one of the most terrestrially-adapted mudskippers, Periophthalmodon schlosseri, using the corrosion casting technique. The vascular system of Pn. schlosseri retains the typical fish configuration with a serial connection of the gills and the systemic circuits, suggesting a lack of separation of O 2-poor systemic venous blood and O 2-rich effluent blood from the air-breathing surfaces. The gills appear to play a limited role in gas exchange, as evidenced from the sparsely-spaced short filaments and the modification of secondary lamellar vasculature into five to eight parallel channels that are larger than red blood cell size, unlike the extensive sinusoidal system seen in purely water-breathing fishes. In contrast, the epithelia of the bucco-opercular chamber, branchial arches, and leading edge of the filaments are extensively laden with capillaries having a short (<10 μm) diffusion distance, which strongly demonstrate the principal respiratory function of these surfaces. These capillaries form spiral coils of three to five turns as they approach the epithelial surface. The respiratory capillaries of the bucco-opercular chamber are supplied by efferent blood from the gills and drained by the systemic venous pathway. We also compared the degree of capillarization in the bucco-opercular epithelia of Pn. schlosseri with that of the three related intertidal-burrowing gobies (aquatic, non-air-breathing Acanthogobius hasta; aquatic, facultative air-breathing Odontamblyopus lacepedii; amphibious air-breathing Periophthalmus modestus) through histological analysis. The comparison revealed a clear trend of wider distribution of denser capillary networks in these epithelia with increasing reliance on air breathing, consistent with the highest aerial respiratory capacity of Pn. schlosseri among the four species. © 2011 Wiley-Liss, Inc. Source

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