JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2003 | Volume:3 | Issue:13|Papers Count:8

Timely harvesting of paddy is very important in minimizing field losses. Since this operation is labour consuming and expensive, steps have been taken to evaluate and develope an appropriate harvesting method for Guilan. In this study, a locally -manufactured power tiller-operated reaper and self-propelled reaper were field tested and compared to manual harvesting method. The results shown that, Grain losses significantly differed in reaping and conveying stages. The grain losses for manual harvesting was minimum (2.09%). The average field loss for mechanical harvesting was 2.8%. The actual field capacity of the self-propelled reaper was highest (0.294 ha/h) compared to 0.238 ha/h for power tiller-operated reaper and 0.0078 ha/h for manual harvesting. Labour input in mechanical reaping was 6.6 man-h/ha compared to 118.4 man-h/ha in manual operation. The cost of mechanical harvesting was 53% lower than manual harvesting. The average harvesting costs per ha are Rls. 1041875, Rls.481133 and Rls.483462 for manual harvesting, self-propelled and power tiller-operated reapers, respectively.

Whey can improve the quality and physico-chemical properties of bread and also delay its staling. The effect of whey on loaf bread (Baguette) at four concentration of 20, 30, 40 and 50% of water volume generally required to make paste was compared with controlled sample (0%). The treated samples were examined by the viscoelastography test in three successive days (I, 2 and 3 days). The compressibility, consistency and elasticity of final products were evaluated. The best compressibility and consistency was observed at 20% whey concentration. The best elasticity after three days was observed at 20% whey concentration, as well. The greatest and best specific volume was observed at control followed by 20% whey concentration. By adding whey, the time for secondary and the final fermentation as well as baking time were decreased by 27, 25 and 36%, respectively, as compared with control. Considering the organoleptic properties and the taste panel, the samples containing whey were better than control sample, from the view point of adherence of crust, flavour and odour.

Sediment transport in irrigation channels is an important aspect in design and operation of an irrigation system. Clogging of turnouts and reduction of the conveyance capacity of channels by siltation are problems which frequently met in irrigation system. The present study is focused on evaluation of prediction methods for sediment transport in lined channels. Nine existing practical formulas used for predicting suspended load are adopted. They included the Lan & Kalinske, Einstein, Brooks, Bagnold, Chang et al., Samaga, Van Rijn, Swamee & Ojha, Celik & Rodi. These methods were compared against the field data measured at Hamidieh and Guods system.General flow and sediment input variables required by each transport function, as well as dependent variables are measured. The predicted suspended loads are compared against the measured suspended sediment discharges. A simple test results show that the brooks, Chang et al., Lan & Kalinske and Van Rijn formulas have better Prodiotion as compare with the other methods.

In this study, transparent and flexible polymers including: Polypropylene of 50 and 100µ thickness, Polyethylene of 75, 125 and 150µ, thickness and Polyvenylchloride (PVC) of 80, 150 and 250µ, thickness were used for packing of wheat. Infested kernels to Angoumois grain moth (Sitotroga cerealella 01.) were located in manufactured package by mentioned polymers as target pest. Permeability of mentioned polymers to phosphine were evaluated by calculation of pest mortality percent after fumigation of package with aluminum phosphide tablets, which emit PH3 in air thigh tanks. The results showed that the best polymer for using as internal layer of jute bags, is Polypropylene of at most 100µ thickness.

Designing irrigation canals such that the water level at outlets lays above the whole irrigated area is crucial both from management and economical point of views. The exact analysis of the flow energy, particularly at transitions, before, and after them is a prerequisit to exact water level determination. The Energy loss in abrupt expansions with subcritical flow has been extensively studied by several researches. However, less attentions were focused on supercritical flow in sudden transitions. The objective of this study was to investigate the energy loss in a sudden expansion with "supercritical flow". Subsequently, an experimental physical model was established in the laboratory and the required data were collected accordingly. The expansion ratios of 1:0.7, 1:0.55, 1:0.4 and 1:0.3 were experimentally established and the discharges were changed from 20 to 70 liters per second for each of the ratios. The supercritical flow was generated, using a sluice gate. The flow was entered the expansion after passing the entrance channel of 3 meter length. The calculated energy loss data and the measurement sections were scaled by choosing the specific energy of flow and the inlet flow characteristics as scale factors, respectively. The inlet flow characteristics were selected to be depth, width and the Froud number. Thus the dimensionless energy loss and measurement sections were obtained. The dominant flow parameters affecting the energy loss, mainly bed friction and turbulences, were fully monitored through the whole experiment. An empirical relation was obtained for the energy loss in supercritical flow passing an abrupt expansion. The results of 19 conducted tests were also indicated no significant difference in the regions that were far from the entering jet. These results were obtained based upon the assumption of constant flow depth across the width at the transition entrance. It was also assumed that there was no energy loss between the entrance and the expansion. All the calculations were made based on the gradually varied flow theory.