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RISS 인기검색어
- 검색키워드
- 저자 : Ahmed A Al Nassar (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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INTERTEMPORAL APPROACH TO THE CURRENT ACCOUNT: EVIDENCE FROM SAUDI ARABIA, 1969-1997
Ahmed A Al Nassar,Stephen P Davies,Terutomo Ozawa People&Global Business Association 2000 Global Business and Finance Review Vol.5 No.2
The Saudi Arabian current account (CA) has fluctuated sharply over the last thirty years. The Saudi government has striven to manage its CA balance over time by making necessary adjustments in internal expenditures to achieve intertemporal optimization. This paper tests the effectiveness of such a government policy by way of an intertemporal approach to CA. The estimation results (Granger-causality test, formal test, and equality-of variances test) indicate that the model captures the statistically important features of the current account behavior for the period of 1969-1997, which demonstrates a high level of effectiveness in the Saudi CA management.
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Ammonium phosphate as promised hydrogen storage material
Barakat, N.A.M.,Ahmed, E.,Abdelkareem, M.A.,Farrag, T.E.,Al-Meer, S.,Al-Deyab, S.,Elsaid, K.,Nassar, M.M. Pergamon Press ; Elsevier Science Ltd 2015 International journal of hydrogen energy Vol.40 No.32
Most of the reported hydrogen storage materials are either expensive or based on synthetically complicated compounds. Ammonium phosphates are cheap and available product; it is being used as fertilizer. These compounds could be utilized as hydrogen storage materials. Stoichiometrically, mono-, di- and tri-ammonium phosphate can lead to evolve 3.875, 7.867 and 11.903 hydrogen equivalent, respectively. Using Pt/C (20 wt %) leads to produce 17.28, 11.35 and 10.15% from the equivalent hydrogen in the mono-, di- and tri-ammonium phosphate, respectively. Analyzing the obtained gases by GC confirms evolution of pure hydrogen. Moreover, ion chromatography detects and ions in the liquid which indicates hydrolysis of the ammonium phosphate. Ni/C and Co/C NPs can be exploited as catalysts; Ni/C containing 20 wt% metal reveals comparable results to Pt/C. Overall, this study opens promising avenue to develop new catalysts to enhance the hydrolysis of ammonium phosphate to produce hydrogen. Comparing to the reported hydrogen storage materials, ammonium phosphates possess comparable hydrogen content 97.28, 118.3 and 115.72 kg/m<SUP>3</SUP> for mono-, di- and tri-ammonium phosphate, respectively which is very close to the MgH<SUB>2</SUB> (115.5 kg/m<SUP>3</SUP>) and not so far from ammonia borane (148.2 kg/m<SUP>3</SUP>). However, in contrast to these compounds, hydrogen can be released from the introduced storage materials by hydrolysis only using the proper catalyst. Furthermore, the hydrolysis process results in producing different acids; nitrous, nitric and phosphoric acid which should be considered in the reactor construction precautions.
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