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There are instances in which it is desirable to determine relationships among fruit physical attributes. For example, fruits are often graded on the basis of size and projected area, but it may be more suitable and/or economical to develop a machine which grades by mass. Therefore, a relationship between mass and dimensions or projected areas and/ or volume of fruits is needed. Various grading systems, size fruits on the basis of specific parameters. Sizing parameter depends on fruit and machine characteristics.Models for predicting mass of orange from its dimensions and projected areas were identified. Models were divided into three classifications: 1- Single and multiple variable regression of orange dimensions (1st classification). 2- Single and multiple variable regression of projected areas (2nd classification). 3- Estimation of orange shape; ellipsoid or spheroid based on volume (3rd classification). Ten Iranian varieties of oranges were selected for the study. 3rd classification models had the highest performance followed by 2nd and 1st classifications respectively, with R2close to unity. The 2nd classification models need electronic systems with cameras for projection whereas, 1st classification models are used in the simple mechanical systems, except multiple variable ones, of and 3rd classification models need more complex mechanical systems. Among the systems that sorted oranges based on one dimension (Model 2), system that applies intermediate diameter suited better with nonlinear relationship as: M = 0.07b2 – 2.95 b + 39.15 with R2= 0.97.

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The harvested walnut has a relatively high moisture content of 30% compared with the safe storage moisture content of 8%. One of the common means of reducing the moisture content is by drying. For design of drying and other aeration systems for agricultural products including walnuts, the relationship between the drop in pressure and airflow velocity must be known. An airflow resistance apparatus was designed and manufatured to measure the airflow resistance of walnuts. This apparatus consisted of an air compressor, a rotameter, a cylindrical bin and an inclined U-tube manometer. The pressure, drops at airflow velocities of 0.085 to 0.55 (m3/s)/m2, were measured at a constant depth of the nuts. Airflow resistance equations were fitted to the measured data. The results showed that, by increasing airflow rates, an increased drop in pressure was achieved through out walnut column. To study the effect of walnut moisture content on airflow resistance, the drop in pressure was measured at different moisture contents levels of 8.6%, 15.5%, 21.3% and 27%. Results indicated that the drop in pressure decreased with increasing moisture content, especially for high airflow rates.

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Growth indices (WG and SGR), food (FCR) and protein efficiency (PER and PCE) of fingerling Nile tilapia, Oreochromis niloticus,were evaluated in 3 synchronous examinations with 12 treatments in triplicates. Groups of control, canola meal (at rates of 25, 50, 75 and 100%), cottonseed meal (at rates of 15, 25, 35 and 45%), as the replacements of expensive protein sources (fish meal and soybean meal), and azolla (at rates of 13, 21 and 29% of diet) were studied. Growth indices, total food intake and protein intake of the control were the highest of all. They decreased with increase in plant protein in every group (p<0.05). FCR and protein efficiency indices didn’t show significant differences (p>0.05) between control and canola meal (at rates of 25 and 50%), cottonseed meal (at rates of 15, 25 and 35%) and azolla (at rates of 13 and 21%). Total food intake, protein consumption and growth indices decreased, because all plant protein ingredients were unpalatable. If the problem of palatability is solved, it seems that the expensive protein sources replace with canola meal and cottonseed meal at the rates of 50 and 35% respectively, and azolla can be used at the rate of 21% in diets. 

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Knowledge of airflow resistance is an important consideration in designing an appro-priate ventilation system and for proper fan selection. An airflow resistance device was designed and fabricated to measure the airflow resistance of potatoes. The device the composed of an air compressor, a rotameter, a cylindrical bin to contain the potatoes and an inclined u-tube manometer. Airflow resistance of potatoes was measured as a relation-ship between the airflow rate and pressure drop per unit depth (Pa/m) at 12 airflow rates of 0.085 to 0.55 m3/s/m2. Two airflow resistance models, namely, Shedd’s and Hukill and Ives’, were fitted to measured data by using PROC NLIN of SAS. The effect of potato size below 120 g (small), at or above 120 g (large) and unsorted (mixed size), and bed depths of 25, 50, 75 and 100 cm of potatoes on resistance to airflow was determined. Results showed that the airflow resistance of small size potatoes for a 100 cm bed depth was 1.6 times higher than that for large size potatoes, and as the bed depth of potatoes was increased, the airflow resistance was increased.

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Vibration generated by vehicles during road transport has an important effect on the agricultural products damage process, particularly vegetable and fruit. Modulus of elasticity is one of the most important mechanical properties of fruits and its variation can be described as one of the damage criteria during transportation. This research was conducted to evaluate the effects of vibration parameters (frequency, acceleration and duration) and fruit position in the bin, on watermelon damage. At first, vibration frequency and acceleration were measured on the different points of a truck-bed in order to obtain the range of vibration frequency and acceleration distribution during transportation. Second, a laboratory vibrator was used to obtain some factors influencing damage during watermelons transportation. The damage was described as a difference in the modulus of elasticity of the watermelon (flesh and hull) before and after the test. According to the results measured on the truck-bed, the vibration frequency mean values were 7.50 Hz and 13.0 Hz for 5-10 Hz and 10-15 Hz frequency intervals, respectively. Furthermore, vibration acceleration mean values were 0.30 g and 0.70 g for 0.25-0.50 g and 0.50-0.75 g intervals, respectively. Vibration frequency and acceleration mean values were used for vibration simulation. Vibration durations were 30 and 60 minutes and damage was measured for watermelons at the top, middle and bottom positions in the bin. Laboratory studies indicated that, vibration frequency, vibration acceleration, vibration duration, and fruit position, which were taken into consideration as controlled variable parameters, significantly affected the damage (P< 0.01). Damage to the watermelon flesh was higher than watermelon hull. Vibration with a frequency of 7.5 Hz, acceleration of 0.70 g, and duration of 60 minutes caused higher damage levels. Fruits located at the top of the bin showed more damage than those in middle and bottom positions (P< 0.05).