Flow passing through lateral intakes and channel junctions is turbulent. Sediment flow and bed forms areaffected by these flow patterns and vice versa. In this research, a laboratory study was carried out toexplore a possible method for sediment control for a set of submerged vanes and a single spur ...
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Flow passing through lateral intakes and channel junctions is turbulent. Sediment flow and bed forms areaffected by these flow patterns and vice versa. In this research, a laboratory study was carried out toexplore a possible method for sediment control for a set of submerged vanes and a single spur dikesimultaneously. Since a larger portion of the near-bed flow was diverted, the intake received a relativelylarge amount of bed load material; thus, appropriate and reliable methods were needed to minimize theamount of diverted sediment materials into the intake channel. The submerged vane creates a tip vortex andthen the helical flow downstream reduces movement of bed sediment into the diversion. In this study, theoptimum dimension, number and array of vanes were selected as determined by the regular design method.To guide flow into the diversion and increase vane performance, a single spur dike was utilized at theopposite side of the intake channel. The location, length and angle of the spur dike were optimized usingthe results of previous testing. The flow patterns for three diversion ratios (13%, 18%, and 24%) and a 25cm spur dike positioned 80 cm from the intake at a 45° angle. The flow depth was measured using a pointgauge and three dimensional velocities (u, v, w) at five levels above the bed as measured by ADV. Afterthe sediment flow reached equilibrium, the channel bed was fixed. The length of separation at the intakechannel was decreased by increasing the diversion ratio. By setting a spur dike opposite to the intakechannel, the width of the separation line decreased at the channel bottom and increased at the surface,decreasing the amount of sediment ingestion in the intake channel.
Pressurized irrigation is a recent development that consumes more energy for the pressure produced. In thisstudy, energy consumption, waste and efficiency were investigated at a diesel and electrical sprinklerirrigation pumping plant in some fields in Hamadan province during 2007-8. Nebraska performance ...
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Pressurized irrigation is a recent development that consumes more energy for the pressure produced. In thisstudy, energy consumption, waste and efficiency were investigated at a diesel and electrical sprinklerirrigation pumping plant in some fields in Hamadan province during 2007-8. Nebraska performance criteria(NPC) were used to compare sprinkler irrigation pumping plant performance. The results showed that theaverage overall energy efficiency for 17 fields for the electrical pumping plants was 46.6% (70.6% NPC)and 12.7% for the diesel pumping plants (52.9% NPC). Average fuel wastage for the diesel and electricalpumping plants was 3.9 l diesel per h and 12.1 kWh, respectively. The average electromotor and pumpefficiency were 92.4% and 42.2%, respectively, at the sprinkler irrigation pumping plant that did notconnect directly to a well. Only the average electromotor efficiency was greater than the NPC. Factorsaffecting the overall energy efficiency reduction were improper pump or motor size, a worn-out pump ormotor, and incorrect installation of a pump or motor.
An assessment of irrigation networks shows that their utility is less than expected because of poor designand operation, lack of sufficient maintenance and poor management. Poor performance of irrigationnetworks is partly because of old components that require rehabilitation. Rehabilitation of irrigationsystems ...
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An assessment of irrigation networks shows that their utility is less than expected because of poor designand operation, lack of sufficient maintenance and poor management. Poor performance of irrigationnetworks is partly because of old components that require rehabilitation. Rehabilitation of irrigationsystems are done case-by-case, which lacks integration and a systemic approach and has not led toappreciable improvement. The involvement of so many components in irrigation rehabilitation and theircomplex interactive relation on system performance requires a system dynamics approach. Simulationtechniques must be explored that represent complex dynamic systems in a realistic way. System dynamics,a feedback-based object-oriented simulation approach, was used to model the rehabilitation of irrigationnetworks. The ease of model modification in response to changes in the system and the ability to performsensitivity analysis make this approach attractive for modeling the rehabilitation. In this paper, theproposed approach was applied to rehabilitate irrigation networks where the main elements affecting thenetwork utility were efficiency, adequacy, equity, flexibility and stability in water delivery. Severalrehabilitation scenarios were considered and their effects on the performance element (efficiency) wereinvestigated. The long-term impact of the system utility was determined using system dynamics modelingand the appropriate policies were selected. The Qazvin Irrigation Network was selected as a case study.The three scenarios for network rehabilitation were fixing the area under cultivation, decreasing drawdown of groundwater and increasing investment in rehabilitation projects. The effect of the scenarios on theefficiency of the system was calculated and the final impact on the system utility was determined. Theresults showed that all three scenarios improved system utility, however, fixing the area under cultivationshowed the best improvement.
It is essential obtain adequate data on the physical and mechanical properties of a crop to reduce crop lossand maintain the quality of crops at and after harvest and to design and optimize machines for post-harvestprocessing. In this investigation, the physical and mechanical properties of nectarines ...
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It is essential obtain adequate data on the physical and mechanical properties of a crop to reduce crop lossand maintain the quality of crops at and after harvest and to design and optimize machines for post-harvestprocessing. In this investigation, the physical and mechanical properties of nectarines (var. Independence)from the Takestan region of Qazvin province were studied. The largest diameter (61 mm); mean diameter(59 mm); smallest diameter (57 mm); mass (97.74 g); volume (1123.17 cm); density (0.99 g/N); geometricmean diameter (59.10 mm); surface area (102/30 cm2); and sphericity coefficient (97%). The chemicalproperties showed acidity for Independence nectarines to be 1.3% and sugar to be 11%, making it tart. Thecoefficient of friction for multi-layer materials (wood, aluminum, galvanized sheet metal) showed a staticfriction coefficient varying from 0.321 for an aluminum surface to 0.389 for a wood surface layer. Inaddition, the break force was 58.9 N, deformation was 10 mm, and fracture energy at break point 0.3 J and1.34 kJm-3.
After harvesting, pistachio nuts are generally kept in storage before being exported. During handling, thenuts are exposed to external forces that cause mechanical damage to them. The increase of the mechanicaldamage is a function of storage conditions, especially temperature. This research investigated ...
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After harvesting, pistachio nuts are generally kept in storage before being exported. During handling, thenuts are exposed to external forces that cause mechanical damage to them. The increase of the mechanicaldamage is a function of storage conditions, especially temperature. This research investigated the effect ofstorage temperature (25, 5, -5, -15°C), on the mechanical properties of pistachio kernels. The kernels werekept at the four storage temperatures for three months. Durability, impact, compression and comminutiontests were then performed on the kernels. The statistical analysis of the data indicated that the negativetemperatures had lower durability damage, but caused the kernels to become brittle, which increasedimpact damage. In the compression test, the modulus of elasticity of the kernels at 25, 5, -5, -15°C were64.17, 63.11, 37.70 and 26.56 MPa, respectively. This also indicated that the power required to causebiological yield in the kernels increased as storage temperature increased. The comminution test showedlittle difference in the distribution of broken kernels on different sieves.
The high cost of direct planters is a limitation in the development of no-till planting for row crops.Attaching appropriate coulters to conventional row crop planters can adapt existing tilled soil planters for ano-till system. In this study, two types of commonly-used disk coulters for no-till planters ...
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The high cost of direct planters is a limitation in the development of no-till planting for row crops.Attaching appropriate coulters to conventional row crop planters can adapt existing tilled soil planters for ano-till system. In this study, two types of commonly-used disk coulters for no-till planters (plain and fluted(waved) were tested for installation at the front of a common vacuum planter with runner openers. Theperformance of the coulters was first compared under different vertical loads and forward speeds and fortwo soil moisture contents (dry and moist). The results showed that the plain coulters cut the residues, butcould not produce a strip of fine soil wide enough for the runner openers at an appropriate depth. However,the fluted coulter in dry soil cut the residues properly as well as loosening a strip of soil 25-34 mm wide toa depth of 24-40 mm. Thus, in dry soil at a forward speed of less than 1.35 m/s, applying a vertical loadequal to one-fourth the weight of a conventional vacuum row planter on a fluted coulter created a 31 mmwide strip of fine soil to a depth of 35 mm. The installation of four fluted coulters on the tool bar of a fourrow vacuum planter (in front of each planting unit) sufficiently distributed the machine weight on the drivewheels and coulters to create the vertical load required for both soil-wheel contact and penetration of thecoulters into hard soil. This allowed adequate uniform placement of seeds at the desired depth. Maintaininga forward speed of 1.35 m/s guaranteed 95% soil coverage for an emergence rate of 83%. In moist soil, thefluted soil threw the soil outside the planting strip and, thus, is not recommended.
This research was conducted with two varieties of almond kernel (thin shell and semi stone shell) for fivemoisture levels (5%, 10%, 15%, 20%, 25% d.b.) with five replications using completely randomized basefactorial design. The results showed increases with increasing moisture content from 5% to 25% ...
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This research was conducted with two varieties of almond kernel (thin shell and semi stone shell) for fivemoisture levels (5%, 10%, 15%, 20%, 25% d.b.) with five replications using completely randomized basefactorial design. The results showed increases with increasing moisture content from 5% to 25% for thethin shell almond for the following variables: true density (851.12 to 1138.94 Kg/m3); porosity (35.69 to54.45%), terminal velocity (4.81 to 6.18 m/s); static friction coefficient on Plexiglas (0.471 to 0.591); staticfriction coefficient on galvanized iron (0.417 to 0.552); projected area (1.45 to 1.67 m2); repose angle(18.26° to 27.59°). Corresponding values for the semi stone shell almond were: true density (897.18 to1123.84 Kg/ m3); porosity (32.09 to 47.22%); terminal velocity (5.35 to 6.53 m/s); static friction coefficienton Plexiglas (0.368 to 0.458); static friction coefficient on galvanized iron (0.356 to 0.447); projected area(1.36 to 1.53 m2); repose angle (16.33° to 22.45°). The results also showed that bulk density decreased asmoisture content increased from 5% to 25% for the thin shell (547.26 to 518.76) and semi stone shell (609to 592.94 Kg/m3).
