فصلنامه تحقیقات مهندسی کشاورزی
سال یازدهم شماره 2 (تابستان 1389)

The rice conversion process is an agricultural transformative industry that consumes a great deal of fossil fuel and electricity. In this study, the effect of different factors on energy consumption, energy consumption index and whitening index were investigated. The experimental design was a split plot design with four whitening periods (15, 30, 45, 60s) (main plot), three rice varieties (Khazar, Beenam, Alikazemi), three levels of final paddy moisture content (9.5-11%, 11-12.5%, 12.5-14% wb) and three replications for each test. The statistical analysis outcomes for energy consumption, energy consumption index and whitening index indicated that as whitening time increased, energy consumption increased and its index decreased. In the 15 and 60s whitening periods, decreasing the moisture content to 9.5-11%, significantly increased the energy consumption index. The energy consumption index of the Khazar variety was significantly higher than the other two varieties at all levels of moisture content. Increasing moisture content caused increased rice breakage, which resulted in decreasing quality and whitening indices. When the whitening period increased to 60¬¬¬s, the whitening index increased significantly. The whitening index of the Khazar variety was significantly greater than those of the other varieties. The results showed that the best state, considering the energy consumption index and whitening index, was obtained at 9.5-11% moisture contents and a 15s whitening period for all varieties.

The effect of grain size, tailwater depth and grain Froude number on local scour caused by submerged horizontal jets issuing below a sluice gate was investigated. Noncohesive sediments with two gradations downstream of a horizontal apron were used in the experiments. The experiments were carried out at different inflow Froude numbers and a range of tailwater depth from low to high submergence. Variations in the maximum depth of scour, height of dune and longitudinal extension of scour hole were plotted by tailwater depth, grain size and grain densimetric Froude number. Results showed that the effect of tailwater depth depends on the grain densimetric Froude number. Also, the similarity between non-dimensional scour profiles, one of the most controversial problems in previous studies, was proven. Finally, the extension of scour hole was plotted in the form of nondimensional parameters that can be used in any unit system.

This study describes the design, construction and calibration of an adjustable three-point hitch dynamometer. The dynamometer frame design was based on an inverted U-shaped frame that was mounted between the tractor links and implement. The dynamometer frame design allows for use in both category I and II three-point hitch systems because of its flexibility in a lower point hitch spread and mast height adjustment. The dynamometer was designed to measure the maximum resultant horizontal and vertical forces of 50 kN and 30 kN, respectively. The force sensing elements comprised three steel extended octagonal ring transducers located between the frame and implement. Electrical resistance strain gauges were installed on the extended octagonal ring transducers at strain angle nodes to monitor draft and vertical forces independently at the ring center. The data acquisition system consisted of a DT800 programmable data logger and a laptop computer. Field tests on the dynamometer and data acquisition system showed that they were able to function effectively. The field experiments to collect data for evaluation of the three-point hitch dynamometer were done using a subsoiler. Field tests were conducted at soil moisture levels of 21.2 and 9.2% at two operating tillage depths with four replications. A T-test was utilized for mean comparison of the three-point hitch dynamometer and drawbar dynamometer data. A drawbar dynamometer was installed between the two tractors which the front tractor used to pull the tractor with a three point hitch dynamometer and the subsoiler connected to the dynamometer. The advantages of the three-point hitch dynamometer make it advisable for horizontal and vertical force components measurement at production fields for common agricultural tractors in Iran.

عوامل مؤثر بر نيرو و انرژي براي جداكردن زيره از بوته زيرة سبزمحمد حسین سعیدی¬راد*، احمد طباطبائی¬فر و فوژان بدیعی*** نگــارنده مسئــــول، نشانی: مرکز تحقیقات کشاورزی و منابع طبیعی خراسان رضوی، ص. پ. 488، تلفن: 3822373 (0511)، پیا‌م‌نگار: saiedirad@yahoo. com** به ترتیب استادیار پژوهش بخش تحقیقات فنی و مهندسی مرکز تحقیقات کشاورزی و منابع طبیعی خراسان رضوی؛ استاد دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران؛ و استادیار پژوهش مؤسسه تحقیقات فنی و مهندسی کشاورزی تاریخ دریافت: 20/6/88؛ تاریخ پذیرش: 15/12/88 چکیده زیرة سبز گیاهی یکساله و یکی از گیاهان زراعی مستعد برای مناطق خشک و نیمه‌خشک ایران است. زيرة سبز به¬ دلیل نیاز آبی کم و کوتاه بودن فصل رشد آن در سال¬های اخیر مورد توجه کشاورزان قرار گرفته است. زيرة سبز در زمان برداشت مقاومت كمي در برابر ريزش دارد و اگر توجه نشود بخش عمده¬اي از محصول از دست مي¬رود. دلیل ريزش دانه در حين برداشت يا قبل از آن، كاهش نيروي اتصال دانه به بوته است. لذا به منظور بررسي: الف) عوامل مؤثر بر مقاومت دو سطح (در امتداد محور طولی دانه و عمود بر آن) و ب) نوع زیره (دیم و آبی) بر نیرو و انرژی لازم برای جدا کردن دانه از بوته این تحقیق عملی شد. نتایج نشان داد که میانگین نیرو و انرژی لازم برای کندن دانه¬های زیره از بوته به ترتیب برابر 995/0 نیوتن و 747/0 میلی¬ژول است. همین مشخص شد که رطوبت مهمترين فاكتوري است كه نيرو و انرژي مورد نياز براي كندن دانة زيره را تحت تاثير قرار مي¬دهد به‌طوری‌که با افزایش رطوبت، نيرو و انرژی مورد نياز براي كندن دانه افزایش می¬یابد. نتایج بررسی اثرهای دوگانة جهت کندن و رطوبت نشان داد که بیشترین اختلاف بین سطوح مختلف جهت کندن، در رطوبت 9/5 درصد است. در صورت اعمال نیرو در جهت عمود بر محور دانه، نیرو و انرژی مورد نیاز برای کندن دانه به ترتیب 26 و 20 درصد نسبت به حالت اعمال نیرو در امتداد محور دانه کاهش می¬یابد. همچنین کمترین اختلاف بین سطوح مختلف سرعت، در رطوبت 9/5 درصد است و در سطح رطوبت 5/13 درصد، اختلاف بین هر سه سطح سرعت معنی¬دار و بیشترین تأثیر سرعت بر انرژی کندن دانه زیره در این رطوبت است. واژه¬های کلیدی انرژی کندن دانه، زیرة سبز، نیروی کندن دانهEffective Factors on Force and Energy Requirements for Picking Cumin SeedM. H. Saiedirad*, A. Tabatabaeefar and F. Badiee* Corresponding Author: Assistant Professor, Agricultural Engineering Research Department, Agriculture and Natural Resources Research Center, P. O. Box: 488, Khorasan Razavi, Iran. Email: saiedirad@yahoo. comCumin (Cuminum Cyminum) is an annual suitable for the dry and semi-dry areas of Iran. Recently, farmers have chosen to plant cumin because it requires less water and growth time. However, at harvest time, the resistance of cumin seed to shatter is low and, if careful attention is not paid to this fact, a major portion of the crop can be lost. When the connection force of the seed decreases, seed shatter falls. To investigate effective factors in shatter resistance, this study measured the force and energy required to pick cumin seeds. The effects of moisture content at three levels (5. 9, 13. 5 and 22%), picking rate at three levels (50, 200 and 500 mm/min), direction of picking at two levels (vertical and horizontal on axial seed) and type of plant at two levels (irrigation and no-irrigation planting) were studied on the force and energy requirements for picking cumin seed. The results showed that the mean force and energy requirement was 0. 955 N and 0. 747 mJ, respectively. It was shown that moisture is the most effective factor in relation to the force and energy requirements. As moisture content increased, the amount of picking force and energy increased significantly. An investigation of the double effects of moisture and picking direction showed that the greatest difference between direction levels was related to a moisture content of 5. 9%. At this moisture, vertical picking of the axial seed required decreased force and energy of 26% and 20%, respectively. An investigation of the effects of moisture and picking rate showed that the least difference between picking rate levels was related to a moisture content of 5. 9%. However, at moisture content 13. 5%, velocity had the greatest effect on the energy requirement and the three picking rate levels all showed significant differences.

In this research, the mechanical properties of seven types of nanofilm with differing amounts of silver and silver-clay particles were studied. The elasticity of modulus, tensile strength, toughness, elongation at break, tear strength and color of nanofilms were compared with those of ordinary LDPE film. Results showed that the inclusion of nano particles increased the modulus of elasticity, tensile strength and tear strength 1.1 to 2.5 times. However, elongation at break point and toughness of the films decreased 1.4 to 4 times. The effect of film type on modulus of elasticity, tensile stress and tear strength was significant at the 0.01 level and for elongation at break point and toughness was significant at the 0.05 level. An investigation of film color parameters and ∆E showed that the 1000 ppm nano silver film had more color than the other films. The smallest ∆E was for the control film. The ∆E value of the nano silver films increased as nano particle content increased and, in nano composite films, decreased as clay content increased. Overall, the nano film with 1000 ppm nano silver content was the best film and the control film was the worst. In conclusion, the nano composite film (SC3) with 500 ppm nano silver and 450 ppm nano clay content was the best film in terms of its mechanical properties. The dark color of this film, however, is an undesirable aspect for food packaging. This may be alleviated by color-removing procedures or by use of the films with lower nano particle content.

The scarcity of irrigation water and decrease of water resources are the most important limiting factors in crop production in countries such as Iran. Thus, studying the optimum use of water and increasing water use efficiency are essential to the agricultural sector. The use of a low pressure hydroflume has been suggested to replace traditional surface irrigation methods. The aim of this research was to compare water distribution in the hydroflume with traditional and sprinkler irrigation systems. Farms in the Kabodarahang plain were selected for the evaluation of water consumption, yield, irrigation efficiency and water productivity. The results showed that most water loss in the farms irrigated by hydroflume was deep percolation and, in the farms irrigated by traditional furrow irrigation, was runoff and deep percolation. The amount of runoff loss in the traditional and hydroflume methods were 25.8% and 15%, respectively. In the hydroflume method, the average of potential efficiency of low quarter was 50, application efficiency of low quarter was 48.2, distribution uniformity was 79.2, and uniformity of the Christiansen coefficient was 77. These parameters for the traditional method were 44.8, 34.9, 87.65, and 89.1, respectively. For the sprinkler method, they were 57.6, 56, 70.3 and 76.6, respectively. The water productivity for the traditional, hydroflume and sprinkler irrigation systems were 1.2, 2.4 and 3.2 kg/m3, respectively. The venue of hydroflume irrigation relative to traditional irrigation increased by 39376600 rails/ha. The ratio of benefit per cost in hydroflume irrigation systems was 6.

In this study, the physical properties were determined for one type of Cornelian cherry (Cornus mas L.) fruit and pit from the Alamout region of Qazvin. The average values for length, width, thickness, 1000 fruit mass, unit mass, geometric mean diameter, unit volume, surface and projected areas, sphericity, fruit (true) and bulk densities, porosity and terminal velocity were 18.91, 13.74, 13.33 mm, 2309.78 and 2.31 g, 15.12 mm, 1841.96 mm3, 722.65 mm2, 180.66 mm2, 80.21%, 1.10 g/cm3, 0.63 g/cm3, 43.30% and 13.8 m/s, respectively. The respective values for the pits were 13.61, 6.07, 5.79 mm, 299.67 and 0.3g, 7.81 mm, 252.93 mm3, 192.57 mm2, 48.14 mm2, 57.59%, 1.21 g/cm3, 0.68 g/cm3, 44.05% and 7.4 m/s. The flesh/pit ratio obtained was 6.8. The static coefficient of friction was 0.38 for galvanized iron, 0.33 for plexiglass, 0.34 for steel and 0.43 for plywood.