

Articles
by
Alireza Keyhani 
Total Records (
3 ) for
Alireza Keyhani 





Payman Salami
,
Hojat Ahmadi
and
Alireza Keyhani


Problem statement: The aim of this research is to determine the energy indices and to make a cost analysis of strawberry grown in open field in Kamyaran zone of Iran. Approach: The data used in the study were obtained from 35 local strawberry growers by using a facetoface questionnaire in AugustSeptember 2009. Results: Total energy input for strawberry production was calculated to be 36822.9 MJ.ha^{1}. The Energy ratio was 0.48 and energy productivity was found to be 0.25 kg.MJ^{1}. About 74.5% of the total energy inputs used in strawberry production was nonrenewable while only about 25.5% was renewable. The share of 56.6% of the total energy input was depended on the indirect form, whereas 43.4% of the total energy input was in the direct form. Specific energy was 3.96 MJ.kg^{1}. Economic analyses showed that profit/cost ratio and net profit were 1.49 and 4616.9 $.ha^{1}, respectively. Conclusion: The net energy in the study area was negative. This means that the amount of output energy is less than input energy and production in this situation is irrational, thus efficient use of resources and proper land management is needed. 





Ali Mohammadi
,
Shahin Rafiee
,
Alireza Keyhani
and
Zahra Emam  Djomeh


Drying behavior of kiwifruit slice was studied at 40,
50, 60, 70 and 80^{o}C and at a constant air velocity of 1.5 m/s
for constant sample thickness of 4 mm in a thin layer dryer. Sample weight,
temperature and drying air velocity were measured during drying and drying
curves were obtained for each experimental data. The curves were fitted
to twelve different semitheoretical and/or empirical thinlayer drying
models to estimate a suitable model for drying of kiwifruit. Coefficients
were evaluated by nonlinear regression analysis. The models were compared
based on their coefficient of determination (EF), root mean square error
(RMSE) and reduced chisquare (x^{2}). Midilli model had the highest
value of EF (0.999319), the lowest RMSE (0.032536) and x^{2 }(0.001119).
The Midilli model was found to satisfactorily describe the drying behavior
of kiwifruit. 




Elham Meisamiasl
,
Shahin Rafiee
,
Alireza Keyhani
and
Ahmad Tabatabaeefar


Drying is one of the primary methods of food preservation. Determining coefficients used in drying models is essential to predict the drying behavior. The present study was conducted to compute drying characteristics of apple slices. Thin layer drying kinetics of apple slices (varietyGolab) was experimentally investigated in a convective dryer and the mathematical modeling was performed by using thin layer drying models in the literature. Drying characteristics of apple slices were determined using heated ambient air at temperatures between 40 and 80^{o}C, velocities at 0.5 m/s and thickness of thin layer 2, 4, 6 mm. Beside the effects of drying air temperature, effects of slice thickness on the drying characteristics, drying time and quality of dried product were also determined. Drying curves obtained from the experimental data were fitted to twelve different thin layer drying models. All the models were compared according to three statistical parameters, i.e. Root Mean Square Error (RMSE), chisquare (X^{2}) and modeling efficiency (EF). The results showed that increasing drying air temperature resulted to shorter drying times. Midilli model had the highest value of EF (0.999611), the lowest values of 0.031806 and 0.001088 for RMSE and X^{2} respectively. The Midilli model was found to be the best model for describing the drying curves of apples. The effects of drying air temperature and thickness on the drying constant and coefficient were also shown. 





