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Experimentally tuned dual stage hydrogen compressor for improved compression ratio
Bhuiya, M.M.H.,Lee, C.Y.,Hwang, T.,Munira, S.,Hopkins, R.,Yoon, H.,Park, S.H.,Kim, K.J. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.24
An experiment-driven design procedure for optimizing the combination of stages of a dual stage hydrogen compressor with enhanced compression ratio is presented herein. Three different combinations of reactors were used using LaNi<SUB>5</SUB>, Ca<SUB>0.6</SUB>Mm<SUB>0.4</SUB>Ni<SUB>5</SUB> and Ca<SUB>0.2</SUB>Mm<SUB>0.8</SUB>Ni<SUB>5</SUB> as hydrogen storage materials. Compression ratios were found to be similar for low supply pressure conditions, which improved significantly for high supply pressure conditions in single stage experiments. A dual stage compressor system with LaNi<SUB>5</SUB> in first stage and Ca<SUB>0.2</SUB>Mm<SUB>0.8</SUB>Ni<SUB>5</SUB> in the second stage was proposed based on single stage results, which was found to be very effective for enhancing compression ratio. Results show that 53% higher compression ratio can be attained by selecting appropriate storage materials for stages, compared to LaNi<SUB>5</SUB> based economic dual stage system.
Crop-Specific Productivity and Efficiency of Bangladesh Rice Crops and Development Policy
( K. M. M. Rahman ),( M. I. Mia ),( Jong Hwan Ko ),( M. K. J. Bhuiya ) 한국농촌경제연구원 2012 농촌경제 Vol.35 No.2
The rice production of Bangladesh has been investigated using a Cobb-Douglas stochastic frontier production function which incorporated a model for the technical inefficiency effects. The farm level primary data which is used for this study has been collected by stratified random sampling technique. The per hectare production, cost, gross, net returns and benefit cost ratio were the highest for Boro rice. The factors identified in the stochastic production frontiers which are responsible for the increase of Aus rice production are irrigation cost, land under production, experience and education. For Aman rice, fertiliser, manure, land under production and education were important variables for the increase in production. For increasing the production of Boro rice, fertiliser, manure, ploughing cost, irrigation cost, insecticide cost and land under production were found to be important variables. Cobb-Douglas stochastic production frontiers included the farm-specific factors such as age, education, experience, family size and land under house. Experienced farmers tend to have smaller inefficiencies than younger and less experienced farmers. There were significant technical inefficiency effects in the production of Boro rice. As a policy, Aus and Aman rice crops production cannot be increased by increasing efficiency with existing technology. In this case a new advanced technology is needed to increase production. But for Boro rice, about 14% of production can be increased by increasing the technical efficiency only.
Hong, Jung‐,Pyo,Yoon, Sung‐,Woon,Hwang, Taeseon,Oh, Joon‐,Suk,Hong, Seung‐,Chul,Lee, Youngkwan,Nam, Jae‐,Do,Bhuiya, Md Mainul Hossain,Kim, Kwang J. Wiley Subscription Services, Inc., A Wiley Company 2012 Polymer engineering and science Vol.52 No.11
<P><B>Abstract</B></P><P>A novel thermal‐barrier composite system was developed by incorporating fusible metal particles in the epoxy matrix system. Using the latent heat of melting, the Sn/In metal particles having melting temperature at 125°C were imbedded in the polymer matrix to suppress the thermal shock and transient temperature variation. The high‐density metal particles were successfully dispersed in the polymer matrix without sinking by incorporating inorganic particles of aluminum nitride (AlN) and boron nitride (BN), which desirably facilitated the heat dissipation to give a high thermal conductivity at around 10 W/m‐K. Under the repeated melting and cooling cycles, the spherical shape of metal particles and the latent heat of melting were retained demonstrating the reversible thermal‐barrier capability of the developed composite system. Under the constant‐heating conditions, it was validated that the temperature rise was delayed by the endothermic melting of Sn/In particles. The developed composite system could find various applications since it could minimize damages caused by the repeated thermal fatigue and/or accidental thermal shock. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers</P>