Iranian Journal of Biosystems Engineering
Year:2009 | Volume:40 | Issue:1|Papers Count:13

A paper-pot transplanter was designed, developed and evaluated in the field by transplanting sugar beet seedlings grown in paper pots. A ground-driven counter wheel equipped with an infra-red sensor measures the traveled distance and sends the corresponding signals to a micro-controller. A step motor controlled by the micro-controller turns the driving shaft of the paper-pot metering mechanism to transfer the pots from feeding station to seedling drop tube, where they are released and guided down to the soil furrow made by a shoe type furrow opener. Then the seedlings are then fixed in the soil by a pair of covering discs followed by a pair of press wheels. For field evaluation of the transplanter performance, a factorial experiment was conducted with three levels of transplanter forward speed (0.25, 0.375 and 0.5 m/s) and two levels of seedling growing stage (4 and 6 leaves). The field tests were replicated three times. The evaluated parameters included: mean seedling spacing on the row, lateral deviation of the transplanted seedlings from the row axis, miss index, percent of acceptable vs. unacceptable transplanted seedlings, seedling pot feed rate as affected by the action of the operator, percent of damaged seedlings and percent of survived plants 45 days following transplanting. The seedling growing stage was shown to have no significant effect on the transplanter performance. Forward speed exerted significant effects on plant spacing, miss index, and seedling feed rate as affected by the operator, while having no significant effect on the other evaluated parameters. Working speed of the transplanter was about six times faster than that of hand transplanting. The optimum transplanting speed among the tested levels was 0.5 m/s. At this speed, the percent acceptable transplanted seedlings was 85.6%, seedling feed rate was 98 plants/minute and miss index 5%. Close to one hundred percent of the transplanted seedlings that were irrigated weekly up to 45 days following transplanting survived and maintained their good vigor.

To assess the effect of time and temperature (in the pumice mixing phase of olive oil extraction) on the quantity and quality features of the extracted oil, a series of experiments comprised of three levels of mixing time (10, 20, and 30 min), and three levels of mixing temperature (30, 45, and 60oc) were carried out. The recorded data were analyzed in the framework of a Randomized Complete Block Design (RCBD). A comparison of means as based upon Duncan's Multiple Range Test revealed an increase in oil acidity and peroxide level (decrease in oil quality) with increase in mixing time and temperature. An increase in pumice moisture content, accompanied by a resulting decrease in oil content, was also observed with the increase in mixing time and temperature, ending up with a final decrease in the quantity of oil extracted. The most appropriate time and temperature of pumice mixing during the extraction operation of olive oil for obtaining a reasonable quantity of the most quality oil were finally recorded and suggested as 20min and 30o, respectively.

Vibration generated by vehicles during road transport has an important impact on agricultural products' damage process, particularly in the case of fruits and vegetables. Modulus of elasticity is one of the most conspicuous mechanical properties of fruits, the variation in which can be described as one of the most affecting damage criteria during transportation. This research was conducted to evaluate the effects of vibration parameters (frequency, acceleration and duration) as well as fruit position in the bin, on damage inflicted upon watermelon. Vibration frequency and acceleration were initially measured of different points of truck-bed to obtain the range of vibration frequency and acceleration distribution during transport. A laboratory vibrator was then employed to determine the factors influencing the damage incurred by watermelons during transportation. The damage was described as a difference of modulus of elasticity of watermelon (flesh and hull) before and after the test. According to the results obtained from tests carried out on the truck-bed, 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 in vibration simulation. Vibration durations were 30 and 60 min and the damage was measured for watermelons positioned at top, middle and bottom in the bin. Laboratory studies indicated that, vibration frequency, vibration acceleration, vibration duration, as well as fruit position, which were taken into consideration as controlled variable parameters, significantly affected the extent of the damage. Damage incurred to watermelon flesh was higher than that to watermelon hull. Vibration with a frequency of 7.5 Hz, acceleration of 0.70 g, and duration of 60 min caused the highest damage. Fruits positioned at the top position in the bin incurred more damage than those in the middle and bottom positions.

Simulation of rough rice drying is one of the proper methods for predicting moisture distribution in the product, and throughout the process of drying. The drying process must be well understood and controlled so that design guidelines which reduce or minimize drying damage to rough rice can be established and improved. Therefore, an accurate understanding and description of the drying mechanism must be implemented. Finite element technique for formulation and solution of a set of coupled conductive heat and a diffusive moisture transfer equation to improve grain drying simulation of axisymmetric bodies is hereby employed. A long grain variety, ‘Ali-Kazemi’, was used for the study. During the thin layer drying, the drying air temperature and initial moisture content were 40oC and 32% (d.b.), respectively. Moisture content was measured by minute. Good agreement was observed when the output of the model compared to experimental data obtained by others. The root mean squre error (RMSE) and modelling efficiency (EF) calculated from nonlinear model vs. experimental data, were 0.01 and 0.991, respectively. This shows that simulation data is close to the experimental ones, and the model can be used for moisture content simulation of rough rice drying. The simulated moisture profile and gradient are directly applicable to stress cracking analyses of rough rice. The results of the finite element analysis obtained can be used in rough rice quality evaluation as well as drying simulation studies.

Different conservation tillage practices are nowadays suggested as the best solution for prevention of soil from erosion. This could be done by leaving the previous crop residue on the soil surface. A new idea to plant in the conservation tillage system is the use of punch planters by which one can plant through a heavy depth of previous crop surface residue. The study was conducted using a 2?3 factorial experiment with a Randomized Complete Block Design (RCBD) of four replications. The two variable factors of the experiment were two types of planters (conventional precision planter equipped with seed plate metering device and precision punch planter with a fertilizer attachment for placement of fertilizer simultaneously with seed in a no-till planting system), along with three levels of speed forward (3, 5 and 7 km/h). Field study was conducted to compare the effects of planter type and forward speed on miss index, multiple index, feed index, planting depth means, emergence rate index, final emergence population, coefficient of variation as well as precision index. Results indicated that an increase in forward speed caused increase of miss index, precision index, coefficient variation of plant spaces, as well as decrease in multiple index. However, the effect of forward speed on emergence percentage, emergence rate and planting depth was not significant (P<0.05) and both planters had their greatest feed index value at 5 km/h forward speed. Results also indicated that the precision punch planter had its best performance at a forward speed of 5 km/h.

Colza (Canola) is a crop with high rate of grain loss during harvesting. At harvest, semi-dried grains of canola’s pods are either opened or dropped due to mechanical impacts. Therefore, lots of grains drop before entering combine head. Another obstacle to successful harvest of canola is that ripe grain's pods are twisted together. This results in heavy grain loss at dividers of combine pickup head. The reason is that dividers tend to separate pods by imparting pressure on twisted pods causing heavy grain loss. In the present research, a mechanical attachment was designed, manufactured and mounted on the right hand side divider of a 955-John Deer combine common in local farms. The unit is aimed to separate pods which in turn reduce grain loss. The attachment is made up of two cylinders, each cylinder carrying 20 fingers. A mechanism is fitted to each cylinder to move the fingers in a reciprocating manner. The dual cylinders rotate about their main axes in opposite directions. Movement of adjacent fingers on each cylinder force twisted pods to separate. Field experiments were conducted to evaluate the performance of the unit in comparison with the control. A grain combine with no attachment on the divider was considered as control. The variables consisted of the rotational velocity of the cylinders in three levels (26.5, 53.0 and 79.5 rpm), and the number of fingers on each cylinder (10, 14 and 18). The treatments were arranged as a factorial experiment replicated three times. The forward speed of combine harvester was maintained at 1 km h-1. The weight of grain loss in each treatment was determined and used in subsequent analyses. Statistical analysis of data shows that variation of cylinder speed has significant effect on grain loss at p=0.01. Other results indicate that at rotational speed of 53.0 rpm, the grain loss is the lowest. Number of fingers also exerts a high significant effect on grain loss at p=0.01. Increasing the number of fingers on cylinders resulted in reducing grain loss. The grain loss of the combine harvester equipped with the separating unit was 51.1 kg ha-1 as compared to 61kg ha-1 for the control.

This study involved the development and evaluation of a new filtering technique, as based on adaptive free mass load cell. The technique's application in reduction of vibration and impulse noise (commonly added to the sugar cane harvester yield monitoring signals) was tested. This technique is based upon assimilate spring- mass vibration system of weighing scale with a free mass load cell in its natural frequency and phase. This was achieved through a calculation of free mass. Finally, the scale signals were corrected online through subtracting the free mass load cell signals. Experiments were conducted in a 3 factor randomized complete block design. In a first test of 3 replications, the effects of 6 frequency levels (3, 4, 5, 6, 6.5 and 8 Hz) on vibration table and 3 speed levels (2.2, 2.4 and 2.7 m/s) on elevator simulator were tested on standard division of scale output signals before and after corrections at 9 levels (the first with no correction and 8 correction levels of 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, and 2.7 coefficients). In a second test of 4 replications, the effects of 5 different crop weights of 0, 1.5, 3, 4.5 and 6 Kg were tested. The results indicated that in a wide range of vibration frequencies, different elevator chain speeds and different excess weights on the scale as well as for different impulse strokes, the differences were significant at 1% after and prior to correction and while after correction being made, the standard deviation of scale signals did not exceed 0.4 Kg. either the best correction coefficient was obtained 2.1 for the case of before loading and 2.4 for the case of when crops passing. An important advantage of this technique is its good performance at low frequencies where analog or digital filters can not be employed due to their possibility of eliminating main signals.

Physical characteristics of agricultural products are the most needed parameters in the design of grading, handling, processing and packing systems. Among physical characteristics; dimensions, mass, volume, projected area as well as surface area are the important factors in sizing systems. For an assessment of morphological and physical characters in walnut, four genotypes of sizable kernels, lateral bearings as well as high yielding were selected. Among the studied genotypes no.570 with a nut weight of 12.46 g, 8.25 g kernel weight, 66.21 % kernel percentage, the least length and a diameter of 34 mm was decided as the most favorite genotype. In the case of assessed physical properties the biggest diameter belonged to genotype no.570 (34 mm). The linear model embodying the minor diameter was finally found out as the best model with a high R2 for walnut mass modeling. Models based on minor, intermediate, and major diameters were as well proposed for modeling of walnut mass.

Most the agricultural products incur plenty of wastages in Iran due to lack of suitable accessible markets, therefore it is understood that establishing small scale industries, specially processing industries would be a suitable way for diminishing agricultural wastes and thus promoting its development. The goal of this research was to determine the spatial factors affecting the location allocation of the aforementioned industries in Kermanshah province and to use the appropriate techniques for promoting it. Thus, this study with a recognition of the whole condition of horticulture in the province and with a provision of the most important indexes of these industries, as well as determining their weights from the viewpoint of horticultural industries' managers and experts in the province, and by use of the data base of GIS, provides the needed plans and helps determine the location for these industries. Findings of the research showed that, Kermanshah County ranked first, Paveh, Sahneh and Eslamabad counties were ranked second, while Javanrood, Sarpolezahab, Songhor and Harsin took the third rank, as far as the establishment of horticultural processing industries, in these area is concerned.

High moisture levels in fresh dairy manure provide a suitable environment for growth of pathogens and cause environmental pollution. Dry manure can be used for different purposes in agriculture and in livestock industry. Such heat properties of manure as specific heat, thermal conductivity and thermal diffusivity are important needed factors for the design and development of a suitable efficient dryer. In this research the thermal diffusivity of dairy manure was determined through one-dimensional Fourier solution. Experiments were carried out at 20, 40, 60 and 82% (w.b) moisture contents and at 40, 50, 60 and 70°C temperature levels. Thermal diffusivities of the dairy manure were obtained in a range of from 0.904×10-7 to 2.11×10-7 m2/s. The trend of increase in thermal diffusivity with by increase in temperature was of a linear type. At a certain constant temperature, thermal diffusivity increased by increase in moisture content (from 20% to 40% (w.b.)) while decreasing at contents above 40% (w.b). A polynomial model can adequately estimate the thermal diffusivity coefficient, a, (agreeable with moisture content vs. temperature of dairy manure), with a coefficient of determination of 0.99.

The development of the dominant Lactobacilli population during traditional Liqvan cheese production was investigated using two different molecular methods of: culture dependent RAPD vs culture independent DGGE. Either one of the techniques showed a high degree of capability to identify and detect of this group of lactic acid bacteria. However, some differences were conspicuous during the detection of isolated Lactobacilli. In the culture dependent method RAPD, Lb. plantarum, Lb. paraplantarum and Lb. brevis were identified as the dominant strains in the final product while in the independent culture method DGGE, Lb. curvatus and Lb. sakei which could not be identified in the culture dependent method were also observed. Through RAPD it was possible to prepare the whole quantitative data for bacterial population while the other technique DGGE, reported just the semi-quantitative data. With regard to the advantages and disadvantages of each method, it can be concluded that none of the two are perfect but the limitations of one can be overcome by the versatility of the other. A combination use of the two methods can help obtain more trustable information about bacterial population dynamic during the cheese making process.

Paste of big head carp fish was prepared based on three formulas and was selected base on organoleptic properties test results. The product was then divided into three portions of: sample 1 (control), sample 2 (containing 0.01% Butylated Hydroxy Anisole BHA antioxidant) and sample 3 (containing 0.02% antioxidant BHA). To determine the shelf life, the samples were frozen and kept in cold storage of -18oC. During the certain time intervals of 0, 15, 30, 60 and 90 days microbial tests were performed, and peroxide value Total Volatile Nitrogen (T.V.N), and fatty acids profile determined. TVN of the control sample reached from 11.2 to 25.48 mg/100g respectively at zero time and after 60 days of being kept in cold storage. As for the sample containing antioxidant BHA of 0.01% concentration, the content of TVN reached 25.9 mg/100g after a lapse of 90 days. In the sample containing antioxidant BHA of 0.02% concentration, TVN content reached 25.34 mg/100g after 90 days. Therefore, based upon TVN as the most important index to determine the paste's shelf life, and compared with the shelf life of the control sample, the samples containing BHA with concentrations of 0.01 and 0.02 percent acquired shelf lives of 60 and 90 days respectively. Change in peroxide value in the control sample equaled to 0.9 (meq of O2/kg) in zero time. It reached 1.4 meq of O2/kg after 15 days, and 0.5 meq of O2/kg after 30 days, but it reached 0 meq of O2/kg after being kept for 60 days in cold storage -18oC. Peroxide value in the sample containing BHA with the concentration of 0.01% reached 2.6 meq of O2/kg and in the sample containing BHA with the concentration of 0.02 percent reached 2.2 meqO2/kg after 90 days. During the 90 days of being kept in cold storage, the saturated fatty acids increased slowly in both control and the sample containing 0.02 percent BHA; the mono unsaturated fatty acids decreased while the poly unsaturated fatty acids increased. Omega-6 fatty acids increased swiftly, while the omega-3 fatty acids did so slowly. All the results from the statistics point of view are significant at (p£0.05) level.

Changes in the fatty acid (FA) composition of Iranian UF (Ultrafiltered)-Feta cheese during ripening (3, 20, 40 and 60 days) were studied. With an increase in the ripening period, due to the conversion of FA to secondary metabolites, the percentages of C4:0-C12:0 decreased significantly (P<0.05). However, the percentages of C14:0-C18:2 increased due to the accumulation of these fatty acids or decrease in the percentages of low- and medium-chain fatty acids. Scanning electron microscopy images indicated that with an increase in the ripening period, fat globules were also decomposed in a way that after 20 days of ripening, no fat globules remained in the cheese. Organoleptic evaluation indicated that ripening period did not affect the scores of appearance and piquant taste. After 20 days of ripening, scores for body and texture, flavour and total acceptability were found to be significantly higher than those for the 3 days of ripening treatment (P<0.05).