Original Article
Abstract
The results of an experimental study on the effect of sediment laden flow on hydraulic resistance in a smooth pipe are presented. The experiments were carried out in two horizontal PE pipe flow systems of 66 and 80 mm in diameter. Flows of volumetric concentrations of 0.1% to 5% and particle diameters ...
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The results of an experimental study on the effect of sediment laden flow on hydraulic resistance in a smooth pipe are presented. The experiments were carried out in two horizontal PE pipe flow systems of 66 and 80 mm in diameter. Flows of volumetric concentrations of 0.1% to 5% and particle diameters of 0.04, 0.064, 0.15, 0.25, 0.72 mm were studied in the experiments. The results are compared with the flow resistance of clear water flow in smooth pipes. These results showed that the presence of suspended sediment in the flow where the Reynolds number is low may increase the head loss up to 125% for an 80 mm smooth pipe. The results also confirm an increase in flow resistance with an increase in volumetric concentration and particle diameter. In some experiments with high Reynolds numbers, sediment transport caused a decrease in pressure drop to less than that of clear water flow. Increasing the Reynolds number may decrease the effect of sediment concentration on head loss so that the number approaches that of clear water flow resistance.
Original Article
Abstract
This research was carried out on corn in the Orzuiyeh region of Kerman province over two consecutive seasons (2005-6 to 2007-8). The experiment was done as a split plot with a completely randomized block design and four replications. Four levels of consumed water (60%, 80%, 100% water requirement, water ...
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This research was carried out on corn in the Orzuiyeh region of Kerman province over two consecutive seasons (2005-6 to 2007-8). The experiment was done as a split plot with a completely randomized block design and four replications. Four levels of consumed water (60%, 80%, 100% water requirement, water use based on regional custom) and three varieties (404SC, 700SC, 704SC) were the main factors and the sub-plots, respectively. The measured parameters included irrigation water volume, grain yield, and leaf area index. The results of the SWAP model indicated that a relatively good correlation existed between observation and calculated data, with irrigation treatment values being close to potential evapotranspiration. There were also significant differences between observation and calculated data for the varieties. These differences were observed in values obtained for grain yield and leaf area index. In conclusion, the corn variety 704SC was more suitable than the other varieties for Orzuiyeh region. Considering the salinity of the water available for irrigation (EC = 4 dS/m2) in the region, 1100 mm per m2 of water was required to produce the highest relative grain yield. The results also showed a 7% decline in crop production for every increase of 2 dS/m2 in salinity.
Original Article
Abstract
Solute Transport Processes Are Affected By Soil Pore Water Velocity Distribution. Pore Size Distribution, Which Can Be Used To Infer Pore Water Velocity Distribution, Can Be Estimated From A Soil Water Retention Curve (N). In This Study, A Solute Breakthrough Curve Was Simulated Using Soil Hydraulic ...
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Solute Transport Processes Are Affected By Soil Pore Water Velocity Distribution. Pore Size Distribution, Which Can Be Used To Infer Pore Water Velocity Distribution, Can Be Estimated From A Soil Water Retention Curve (N). In This Study, A Solute Breakthrough Curve Was Simulated Using Soil Hydraulic Parameters In Four Different Soils. To Evaluate The Proposed Model, Predictions Were Compared To That Of The Measured Soil Water Characteristics And Solute Breakthrough Data. A Breakthrough Curve Contains Two Soil Hydraulic Parameters, One Relating To Pore Size Distribution (N), Obtained From The Soil Water Retention Curve, And Pore Connectivity (M). In This Study, M Was In The Range Of -2 To -5. The Silt Content Of The Soil Can Play An Important Role In Determining Pore Connectivity, So An Equation Is Proposed For The Relationship Between Soil Silt Content And Pore Connectivity.
Original Article
Abstract
A mathematical model was developed for freeze drying in which the dimensions and specifications of the condenser were considered for the first time. An appropriate program was written using MATLAB to solve model equations and simulate the process. The software successfully simulated the drying data of ...
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A mathematical model was developed for freeze drying in which the dimensions and specifications of the condenser were considered for the first time. An appropriate program was written using MATLAB to solve model equations and simulate the process. The software successfully simulated the drying data of a suspension of 20% milk recorded in a lab scale freeze dryer. The simulator was then used to investigate the effect of dryer specifications on the timing of primary and secondary drying stages. The results showed that primary drying time is proportional to sample thickness squared, but the secondary drying time is less dependent. Condenser temperature nonlinearly affects both drying times. Dependency weakens with an increase in drying chamber temperature and eventually disappears at chamber temperatures above 255K for primary and 330K for secondary stages. The results also showed that a decrease in the condenser heat transfer area from 2 to 0.5 m2 per kg of initial water will increase secondary stage drying time from 11 to 12 hours.
Original Article
Abstract
Research was carried out in 2007 on 7 native summer-ripening apple cultivars grown in Kamal Abad Karaj Research Station. The 16 year-old plants were grafted onto seed rootstocks. The cultivars were Ghandak-e-Kashan, Golab-e-Isfahan, Golab-e-Kohanz, Mashad, Assali, Ghermez-e-Rezaieh and a new cultivar--Koli-e-Mahallat ...
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Research was carried out in 2007 on 7 native summer-ripening apple cultivars grown in Kamal Abad Karaj Research Station. The 16 year-old plants were grafted onto seed rootstocks. The cultivars were Ghandak-e-Kashan, Golab-e-Isfahan, Golab-e-Kohanz, Mashad, Assali, Ghermez-e-Rezaieh and a new cultivar--Koli-e-Mahallat (syn. ESCR). The aim of the study was to identify changes in qualitative and quantitative traits occurring during cold storage of summer-ripening apples to determine their genetic potential. The fruits were harvested in two stages. The period of cold storage was predetermined to minimize cold storage time for early cultivars and was set at 4, 8, and 16 weeks based on ripening class. The testing intervals were weekly, bi-weekly and 4-weekly testing, respectively. The temperature and relative humidity of the cold storage room were fixed at 0° ± 0.5° C and 80% ± 10%, respectively. Physical and biochemical traits under investigation included weight, firmness, total soluble solids (TSS), titrable acids (TA), pH and flavor index (defined as the ratio of TSS/TA). The results showed that cultivar and harvest time had significant differences. The least loss of fruit weight was observed in Koli-e-Mahallat at the end of cold storage of the first harvest samples. However, for the second harvest, it was recorded in all the cultivars except Golab-e-Isfahan. The greatest firmness registered in Golab-e-Isfahan at the end of cold storage and in Ghandak-e-Kashan and Ghermez-e-Rezaieh for the second harvest. At the end of cold storage, the highest TSS (>12%) was recorded for Golab-e-Kohanz; highest pH (<4) and TA values (>40%) for Mashad. Assali and Golab-e-Kohanz had the highest flavor index (TSS/TA>60%) at the end of cold storage for the first harvest. Koli-e-Mahallat, Assali, Golab-e-Isfahan and Golab-e-Kohanz had the highest values for the second harvest.
Original Article
Abstract
Olive oil extraction methods and technology can affect the quality and quantity of the extracted oil. In this study, qualitative and quantitative parameters were investigated for oil extracted using a hammer crusher at 720 and 1450 rpm at 30°, 40°, 60° C mixing temperatures. The data were ...
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Olive oil extraction methods and technology can affect the quality and quantity of the extracted oil. In this study, qualitative and quantitative parameters were investigated for oil extracted using a hammer crusher at 720 and 1450 rpm at 30°, 40°, 60° C mixing temperatures. The data were analyzed using a complete randomized block factorial design using SPSS software with three replications. The results showed that increasing the temperature and rotary speed had more effect on acidity than did time. The only factor affecting peroxide content was mixing unit temperature. For quantitative parameters, increasing time and mixing temperature resulted in a reduction of the pomace moisture content (increasing quantity). Also, increasing time, mixing temperature and rotational velocity of the crusher resulted in decreased fat content (increased quantity). Hence, to obtain high quality oil, itis recommended that oil extraction be carried out at 30°C mixing temperature and 720 rpm crusher rotary speed for 20 min mixing time.
Original Article
Abstract
High intensity evaporation from the soil surface due to low air humidity and poor soil structure and organic matter are constraints of agriculture in arid and semi-arid regions of Iran. Regionally, maintaining plant residue with tillage management is one method to improve these conditions. In this study, ...
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High intensity evaporation from the soil surface due to low air humidity and poor soil structure and organic matter are constraints of agriculture in arid and semi-arid regions of Iran. Regionally, maintaining plant residue with tillage management is one method to improve these conditions. In this study, for a barley-corn rotation, four barley residue management methods for standing stubble (burning, burying, incorporating and leaving on the surface) were compared over four years at Isfahan Kabootar Abad Agricultural Research Station. The experiment was conducted using a randomized complete block design with six treatments and three replications. The tillage treatments for corn (second crop) were applied to the same plot every year and the plots were conventionally plowed every year for the first crop (barley). The first year results showed that no-tillage treatments reduced the yield due to insufficient contact of seed and soil which caused an inadequate number of seedlings per square meter. However, providing better seed-soil contact in subsequent years resulted in no significant difference in the yield of the no-tillage treatment with other treatments. There was also no significant difference in yield and other crop establishment parameters between the other treatments during the four years of the study. Incorporation, leaving the residue on the surface and burying to a depth of 25 cm resulted in 20%, 18%, 13% increases, respectively, in the average organic matter compared with burning after four years of testing. Results also showed that the earthworm population under the conventional method was significantly lower than for the no-till and reduced-till treatments. No significant difference in root dry weight to a depth of 60 cm was observed between treatments. After four years, the results of the study indicated that the forage corn production under no-tillage and reduced tillage had no adverse effect on biomass yield and can be an alternative method to the current tillage method. Therefore, an annual compilation system that combines conventional tillage for barley and reduced tillage for corn production (after barley) is an alternative to reduce soil moisture evaporation in summer, increase soil organic matter and improve soil structure (increase population of earthworms) instead of conventional tillage operations.
Original Article
Abstract
Part of the process of feed preparation or oil extraction for date pits is to soak the pits in water. Soaking softens the pits and reduces the required milling energy. In this research, the effects of water temperature at 25°, 35°, 55° and 65°C on water absorption and grinding of the ...
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Part of the process of feed preparation or oil extraction for date pits is to soak the pits in water. Soaking softens the pits and reduces the required milling energy. In this research, the effects of water temperature at 25°, 35°, 55° and 65°C on water absorption and grinding of the date pits was investigated. The water absorption curves indicated that the rate of absorption and the final moisture content of the pits increased as the water temperature increased. The final moisture content of the pits for these temperatures were 59%, 62%, 71% and 73% w.b., respectively. Modeling water absorption using analytical, Page and exponential models indicated that the three models showed good fit with the experimental data (R2>0.95). The best results were obtained using the Page model with R2 = 0.99. The results of grinding the pits indicted that the average diameter of the ground particles decreased as soaking time and temperature of the water increased. A logarithmic model was defined to express the diameter of the particles as a function of grinding time. The presented model fit well with the experimental data (R2>0.98).
