A. Nikkhah; B. Emadi; M. Khojastehpour; S. R. Attarzadeh Hossini
Abstract
Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than ...
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Introduction: Too many people are working in the agricultural sector and therefore, pay more attention to the safety and health at work in the agricultural sector is important. This issue is more important in developing industrial countries where the level of the ergonomic working condition is less than that of developed countries. Attention to ergonomic condition of agricultural machinery drivers is one of the goals of agricultural mechanization. Therefore, in this study the ergonomic conditions of brake and accelerator mechanisms for MF285 and MF399 tractor's drivers were investigated using a new method. Materials and Methods: 25 people were selected for experiment. The electrical activity of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus medialis, Vastus lateralis, Quadratus Lumborum and Trapezius muscles of drivers before and during pressing the pedal and after rest time were recorded using Biovision device. Measurements were performed for each person on each muscle 30 seconds before pressing the pedal, 60 seconds after pressing the pedal and after 60 seconds of rest. For all drivers, the muscles on the right side (brake and accelerator side) have been selected and tested. The measurements were performed in compliance with appropriate time intervals between the measurements. Results and Discussion: Ergonomic assessment of brake pedal: The results showed that the RMS electrical activity of muscles of Vastus medialis and Medial gastrocnemius, during 60 seconds braking were 2.47 and 1.97. So, Vastus medialis and Medial gastrocnemius had the highest stress during pressing the MF399 tractor's brake pedal. Moreover, the Medial gastrocnemius and Lateral gastrocnemius with RMS electrical activity ratio of 2.47 and 1.74 had the highest RMS electrical activity ratio respectively, during 60 seconds braking compared to before braking of MF285 tractor. The comparison of results showed that the Vastus medialis and Trapezius had the higher stress during braking of MF285 tractor than that of MF399 tractor, while, muscles of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus lateralis, Trapezius and Quadratus Lumborum showed the lower stress during braking of MF285 tractor. Ergonomic assessment of accelerator: During 60 seconds pressing the accelerator pedal for MF285 the RMS electrical activity of muscles of Quadratus Lumborum and Medialis gastrocnemius were 3.25 and 2.15. So, these muscles had the highest stress during pressing the accelerator pedal for MF285. Drivers of MF399 tractor experienced high stress in their Vastus lateralis and Lateralis gastrocnemius muscles during pressing the accelerator pedal. The results highlighted that for all muscles, except Vastus lateralis, the electrical activity ratio during pressing the accelerator pedal of MF285 tractor were higher than that for MF399 tractor. Conclusions: To conclude, Vastus medialis and Trapezius had the higher stress during braking of MF285 tractor than that of MF399 tractor, while, muscles of Medialis gastrocnemius, Lateralis gastrocnemius, Vastus lateralis, Trapezius and Quadratus Lumborum showed the lower stress during braking of MF285 tractor as compared with the other model of tractor. Generally in all muscles, except Vastus lateralis, the electrical activity ratio during pressing the accelerator pedal of MF285 tractor was higher than that for MF399 tractor and the drivers need more effort while pressing the accelerator pedal and drivers of this tractor had adverse condition while using the accelerator mechanism. Acknowledgements: The research leading to these results has received funding from the Ferdowsi University of Mashhad, Iran, is gratefully acknowledged. Gratitude also goes to Dr. Mohammad Hossein Abbaspour-Fard, Hossein Fallahi and Mehdi Mahjour for their guidance and support throughout parts of this research.
A. Jafari Malekabadi; M. Khojastehpour; B. Emadi; M. R. Golzarian
Abstract
Introduction: Poisson ratio and modulus of elasticity are two fundamental properties of elastic and viscoelastic solids that use in solving all contact problems, including the calculation of stress, the contact surfaces and elastic deformation (Mohsenin, 1986; Gentle and Halsall, 1982).
There are many ...
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Introduction: Poisson ratio and modulus of elasticity are two fundamental properties of elastic and viscoelastic solids that use in solving all contact problems, including the calculation of stress, the contact surfaces and elastic deformation (Mohsenin, 1986; Gentle and Halsall, 1982).
There are many published literature on Poisson ratio and elasticity modulus of fruit and vegetables. Shitanda et al. (2002) calculated Poisson ratio of rice by considering Boussinesq’s theory. They showed that the Poisson ratio is greater for shorter varieties. In another study, researchers used the instrumented bending beam to measure the lateral expansion of red beans. They were considered Poisson ratio as the ratio of transverse strain to the longitudinal strain (regardless of the geometry of the sample) and were calculated modulus of elasticity with Hertz theory for convex bodies (Kiani Deh Kiani et al., 2009). Cakir et al. (2002) was determined the Poisson ratio and elastic modulus of some onion varieties. They used a simple formula to determine the transverse strain that developed by Sitkei (1986) for prism-shaped rod, regardless of the geometry of the product.
Reviewed scientific literature shows that these parameters have not been studied according to the geometric shape of onions and was not used by a more accurate method, such as image processing to determine these parameters. The objective of this study was to evaluate the mechanical properties of two varieties of onions. Poisson ratio was determined with image processing. Considering shape of the onions and deformation value, and using Hertz’s theory with Poisson ratio, modulus of elasticity was calculated. The effects of loading directions (polar or equatorial), deformation value (5, 10 and 15 mm), loading speed (15 or 25 mm min-1) and onion varieties (Red and Yellow) on the modulus of elasticity and apparent Poisson’s ratio were examined.
Materials and Methods: The onions harvested in autumn, 20 days before conducting the tests. Onion samples kept at room temperature (21oC). Onions of each cultivar were randomly selected. Diameters of onion were measured with a digital vernier caliper. In each run, eight onions were randomly selected and the loading test and photography were done together and the average values reported.
All mechanical tests were performed using a Universal Testing Machine (UTM) (Model H5KS, Tinius Olsen Company) between two rigid plates. The loading was made with two constant speeds of 15 and 25 mm min-1. Deformation values were 5, 10 and 15 mm. The onions were loaded either axially or laterally until rupture point and photography were done together.
The initial and current onion diameters along the y and x axes obtained by using image processing and the strains were calculated. Having axially and laterally strains of the onions, the apparent Poisson's ratio was calculated using equation presented by Figura and Teixeira 2007; Kiani Deh Kiani et al., 2009; Pallottino et al., 2011; Kabas and Ozmerzi 2008; Gladyszewska and Ciupak 2009.
A factorial experiment based on a completely randomized design with 8 replications was applied. The significant differences of means were compared by using the Duncan’s multiple range test at 5% significant level. SPSS 20.0 software was used for data analysis.
Results and Discussion: According to the analysis of variance (Table 2), the effects of speed and displacement of loading was significant in 5% probability levels. In addition, interaction effect varieties × directions × speed along Y, varieties × directions, varieties × speed and directions × speed along X was significant in 1, 1, 5 and 5% probability levels, respectively. The average of the apparent Poisson ratio for Yellow onion was less than that obtained for the Red onion, because Red onions have softer texture than Yellow onions. Apparent Poisson ratio was obtained as 0.2623 to 0.4485 and 0.2423 to 0.4179 for Yellow and Red onions, respectively. With increasing deformation, apparent Poisson ratio increased.
Modulus of elasticity along X and Y
According to the analysis of variance (Table 2), the effects of speed and displacement of loading and directions × speed was significant in 1% probability levels. The average of the modulus of elasticity for Red onion was less than that obtained for the Yellow onion because Yellow onion has tougher and more powerful texture than Red onion. Modulus of elasticity were obtained as 2.032 to 5.449 and 1.829 to 5.311 MPa for Yellow and Red onions, respectively. The modulus of elasticity for lateral loading was less than that obtained for the axial loading. With increasing deformation, the modulus of elasticity decreased. The modulus of elasticity for lateral loading in loading speed 25 mm min-1 was less than that obtained for loading speed 15 mm min-1.
Conclusions: The results were summarized as below:
Loading speed, deformation value and their interaction effect were significant in different confidence levels for apparent Poisson's ratio and modulus of elasticity.
The compression force of Yellow onion was more than Red onion. Thus, it can be concluded that Yellow onions have more strength against the forces and loading.
The modulus of elasticity for lateral loading was less than that obtained for the axial loading. It is better to be considered for packaging of onions.
The modulus of elasticity for lateral loading in loading speed 25 mm min-1 was less than that obtained for loading speed 15 mm min-1.
With increasing deformation, the modulus of elasticity and apparent Poisson’s ratio decreased and increased, respectively.
R. Khodabakhshian; B. Emadi
Abstract
Introduction: The economical yield of date fruits depends on many factors (Al-Shahib and Marshall, 2003). One of them is harvesting in optimum stage. Generally, date fruits have four distinct stages of ripeness to satisfy different consumption requirements (e.g., fresh and processed). They are known ...
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Introduction: The economical yield of date fruits depends on many factors (Al-Shahib and Marshall, 2003). One of them is harvesting in optimum stage. Generally, date fruits have four distinct stages of ripeness to satisfy different consumption requirements (e.g., fresh and processed). They are known throughout the world by their Arabic names which are Kimri, Khalal, Rutab and Tamr in order of ripeness (Imad and Abdul Wahab, 1995; Al-Shahib and Marshall, 2003; Sahari et al., 2007). Decreasing moisture content and increasing sugar content happens gradually while the date ripeness approaches to Tamr stage. From Kimri to Khalal stage, the size and acidity decreases when the color of Mazafati variety changes from green to red. The change in acidity continues from Rutab to Tamr stage while color transforms from brown to black. At the final stage of ripeness, Mazafati variety is soft and has a good storability (Al-Shahib and Marshall, 2003). The main Raman techniques commonly applied in agricultural product and food analyzing include dispersive Raman spectroscopy, Fourier Transform (FT), Raman spectroscopy, Surface-Enhanced Raman Spectroscopy (SERS) and Spatially Offset Raman Spectroscopy (SORS). Synytsya et al. (2003) illustrated that FT-Raman spectroscopy is a valuable tool in structural analysis of commercial citrus and sugar beet pectin. Yang and Irudayaraj (2003) employed an FT-Raman approach to detect and classify foodborne microorganisms on the whole apple surface for the first time. Schulz et al., (2005) revealed the potential of FT-Raman spectroscopy in natural carotenoid analysis. Also, many researchers have attempted to apply FT-Raman spectra on the whole fruits and vegetables. FT-Raman spectroscopy was used by Veraverbeke et al. (2005) to evaluate the natural, intact wax layers on the surface of whole fruits. Nikbakht et al. (2011) used a FT-Raman spectroscopy for qualitative and quantitative analysis of tomato ripeness parameters. The scope of this study was to evaluate the feasibility of a nondestructive method based on FT-Raman spectroscopy in distinction of Mazafati date fruits according to four mentioned ripeness stages.
Materials and Methods:
Sample preparation: Mazafati variety of date fruit was used for this study. During the harvest seasons of 2012 (July-August), the samples from each four stages of ripening namely Kimri, Khalal, Rutab and Tamr were collected from two different orchards in Bam, Kerman province, Iran. A number of 100 date samples were tested in this study, and the external features of the four stages are exemplified in Fig.1. To characterize the physical properties of studied samples, the selected physical properties such as initial moisture content, mass, geometric mean diameter, sphericity and density of studied samples were measured using represented methods by Mohsenin (1896), Jahromi et al. (2008) and Shakeri and Khodabakhshian (2011). At least, the samples were kept at 5C in a refrigerator for 7 days to distribute the moisture uniformly throughout the sample. Before spectral acquisition, the required quantities of date fruits in each ripeness stage was taken out of the frig and allowed to warm with room temperature for approximately 2 hr (Khodabakhshian et al., 2012).
Chemical properties measurements: Tissue samples were cut from each fruit separately and were macerated with a commercial juice extractor, filtered and centrifuged. The supernatant juice was used for the determination of sugar content with a manual refractometer, and expressed as percent Brix in the juice. Dry weight percentage of samples (Between 3-5 g) was determined by weighing them first, then dried them at 105ºC in a forced-air oven for 4 h and finally reweighed. PH value of date fruits was determined by a pH meter.
Raman spectroscopic set-up: FT-Raman spectra on the whole fruits in the region 200-2500 cm-1 were recorded using a Thermo Nicolet NEXUS 870 spectrometer (Thermo Electron Corp, Madison, Wis., U.S.A) equipped with a Deuterated Triglycine Sulfate (DTGS) detector and a solid substrate beam splitter. The spectra were collected with rapid scan software running under OMNIC (Nicolet, Madion, Wis., U.S.A) and a resolution of 4 cm-1 by coadding of 128 scans. FT-Raman has three main advantages over dispersive Raman systems: (1) reducing the laser-induced fluorescence that a number of samples exhibit; (2) easing the operation as with a Fourier transform infrared (FTIR) spectrometer; and (3) showing a high spectral resolution with a good wavelength accuracy (Yang and Ying, 2011). Furthermore, the Raman spectra of pure tannin were measured as a reference spectrum. The original data were used for further analysis only after subtracting dark current spectra. For obtaining dark current spectra, the laser was set to zero.
Results and Discussion:
Physical properties of date fruits: The results of some physical parameters of the studied date fruit are shown in Table1. The changes in the physical properties were dependent on the internal quality in different ripeness stages. This justification also was revealed for date fruits by Al-Hooti et al. (1995). The obtained relations between ripening stages and internal quality of studied samples are represented in the next part.
Raman spectra of tannin: Raman features of the tannin in the wavelength range of 200-2500 cm-1 are shown in Figure 3. As shown in the figure, major Raman features of the tannin were observed in the spectral region of 600-1600 cm-1. Three main Raman peaks were identified in this region. The tannin showed its highest Raman intensity at 1590 cm-1, which was higher than that at 1357 cm-1. The other peak (650 cm-1) showed low intensity. As stated by many researchers (Shahidi and Naczk, 2004; Al-Farsi et al., 2005; Biglari et al., 2008), these bands are assigned to stretching C-C, C=C and C-H bonds which compose the structure of phytochemicals. Beyond 1600 cm-1, no notable Raman scattering signals were observed. Themain Raman features of tannin were revealed in the wavelength range of 600 to 1600 cm-1 since the main Raman features of tannin are in the wavelength range of 600-1600 cm-1, this region was used for calculating the spectral information divergence to evaluate the ripeness degree of the date fruits.
Conclusions: This study reports the potential of FT Raman spectroscopy for nondestructive discriminating of Mazafati date fruits according to the four ripeness stages. The analysis of the Raman signal changes that happening during date ripening and its relationship with the ripeness degree of the date fruits was studied. In this regard, changes of pure tannin content in the wavelength range of 200-2500 cm-1 as a good ripeness index for date fruits was investigated. A modified polynomial, Self-Modeling mixture Analysis (SMA( and the Spectral Information Divergence (SID) was performed on different samples at four ripeness stages.
B. Emadi; A. Nikkhah; M. Khojastehpour; H. Payman
Abstract
In this study, the energy and economic analysis of peanut production in Guilan province of Iran was studied. Data were collected from questionnaires of 75 farmers. The data were collected from three farm size categories namely: 0.1–0.5 ha, 0.5-1 ha and larger than 1 ha. The results revealed that 19407.36 ...
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In this study, the energy and economic analysis of peanut production in Guilan province of Iran was studied. Data were collected from questionnaires of 75 farmers. The data were collected from three farm size categories namely: 0.1–0.5 ha, 0.5-1 ha and larger than 1 ha. The results revealed that 19407.36 MJ ha-1 energy input was totally consumed. The highest share of energy consumption belonged to diesel fuel (50.05%) followed by chemical fertilizers (19.14%). The mean difference of energy inputs including machinery, diesel fuel and electricity among different sizes of farms was significant at the 5% level. The average energy efficiency in different farm size categories including less than 0.5 ha, 0.5-1 ha and more than 1 ha were 3.67, 4.02 and 4.12, respectively. The energy productivity of these sizes was calculated as 0.155, 0.169 and 0.174 kg MJ-1, respectively. The Cobb-Douglas model results showed that the effects of inputs including human labor, machinery, chemical fertilizers and electricity on the yield were positive, while the effect of inputs including seed, diesel fuel and chemicals on peanut yield were negative. The benefit-cost ratio was calculated as 1.82. Farmers with a farm larger than 1 ha used the least amount of energy and input costs.
M. Saadatinia; B. Emadi; H. Sadrnia
Abstract
One of the nondestructive methods for assessing the internal quality of some fruits is the processing and analyzing the sound signals generated by an impact on the fruit. In this regard determining the location and the suitable impact levels for a certain fruit is required. In this study, the selected ...
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One of the nondestructive methods for assessing the internal quality of some fruits is the processing and analyzing the sound signals generated by an impact on the fruit. In this regard determining the location and the suitable impact levels for a certain fruit is required. In this study, the selected Crimson sweet variety of watermelon was used for the acoustic tests by imposing the impact force on samples. Acoustic tests were conducted using two independent variables including impact location (two sides of the symmetrical line of watermelon and the opposite of the stem end) and impact levels (12.09, 15.08 and 17.11 kg mm s-1) on the generated sound signals, to evaluate the stiffness of the fruit. The relation between the acoustic signals and the texture of both peel and flesh was examined using puncture test. The results showed that the variation of location and levels of impact on the obtained values of acoustic tests were significant
K. Hedayati; B. Emadi; M. Khojastehpour; Sh. Beiraghi-Toosi
Abstract
Sugar, which can be extracted from sugar cane and sugar beet, is one of the most important ingredients of food. Conducting more research to increase the extraction efficiency of sugar is necessary due to high production of sugar beet and its numerous processing units in northern Khorasan province. In ...
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Sugar, which can be extracted from sugar cane and sugar beet, is one of the most important ingredients of food. Conducting more research to increase the extraction efficiency of sugar is necessary due to high production of sugar beet and its numerous processing units in northern Khorasan province. In this research, the effect of temperature, time and the frequency of ultrasonic waves on mechanical properties of sugar beet and its extraction rate of sugar in moisture content of 75% were studied. In this regard, an ultrasonic bath in laboratory scale was used. The studied parameters and their levels were frequency in three levels (zero, 25 and 45 KHz), temperature in three levels (25, 50 and 70 ° C) and the imposed time of ultrasonic waves in three levels (10, 20 and 30 min). Samples were prepared using planned experiments and the results were compared with control sugar beet samples. A Saccharimeter was used to measure the concenteration of sugar in samples. Two different types of probe including semi-spherical end and the other one with sharpened edges were used to measure mechanical properties. The studied parameters of frequency, temperature and time showed significant effect on sugar extraction and their resulted effect in optimized levels revealed up to 56% increase in sugar extraction compared with control samples. The obtained values of elastic modulus and shear modulus showed a decreasing trend. The obtained values of total energy of rupture, the total energy of shear, the maximum force of rupture, and the yield point of rupture showed an increasing trend. The frequency had no significant effect on the yield point of rupture and shear force.
M. Mohammadi Mogharreb; M. H. Abbaspour-Fard; M. Goldani; B. Emadi
Abstract
The underground temperature at a depth of about three to four meters is almost constant during the year. As a result in summer the underground is cooler than the ambient temperature. This potential is considered for greenhouse cooling by using an Earth-to-Air Heat Exchanger (EAHE). In this research the ...
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The underground temperature at a depth of about three to four meters is almost constant during the year. As a result in summer the underground is cooler than the ambient temperature. This potential is considered for greenhouse cooling by using an Earth-to-Air Heat Exchanger (EAHE). In this research the effects of two parameters were investigated: a) the area of greenhouse in three levels of 9, 18, 27 m2 and b) the percent of vegetation coverage inside the greenhouse in three levels of 0%, 50%, 100% on the performance of EAHE. The experimental design was factorial experiment in a randomized complete block design. The parameters of greenhouse’s inside temperature, thermal energy exchange and coefficient of performance (COP) were considered in cooling mode. As one of the remarkable results it was observed that the closed loop utilization of the system was infeasible in cooling mode. This was mainly due to the occurrence of vapor distillation inside the underground pipes and hence the blockages of the air flow. Also the effect of area and the percent of vegetation coverage were significant on the performance of EAHE. The highest average temperature difference between the temperature of testimonial greenhouse and the temperature of greenhouse was observed in treatment of 100% vegetation coverage and 9 m2 floor area which was measured as 9.6°C. The least average temperature difference in the treatment without vegetation coverage and 27 m2 floor area was measured as 5.2 °C. Considering thermal energy exchange in cooling greenhouse with open loop, the best treatment determined for EAHE in this research was the one with 9 m2 floor area and 100% of vegetation coverage.
E. Velayati; B. Emadi; M. Khojastehpour; M. H. Saeidirad
Abstract
The study of mechanical properties of Berberis not only is useful for design and optimization of transportation, processing and packaging equipment but also can prevent mechanical injuries and losses. In this study force, deformation, energy and toughness were measured at different moisture content levels ...
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The study of mechanical properties of Berberis not only is useful for design and optimization of transportation, processing and packaging equipment but also can prevent mechanical injuries and losses. In this study force, deformation, energy and toughness were measured at different moisture content levels including 70-76, 45-50, 25-30 and 7-10 percent (w.b.). The decrease of moisture content caused increasing rupture force from 1.387 to 2.679 N, decreasing shape deformation from 3.387 to 2.413mm, increasing toughness from 4.297 to 8.220 J/cm3 and decreasing rupture energy from 0.921 to 0.661mJ. Effects of loading speed, force orientation and their interaction were investigated on just fresh Berberis fruit. It was indicated that only force orientation was effective on all investigated properties except toughness. The moisture content was identified as an effective parameter on terminal velocity. It decreased from 9 to 4.5 m/s with decrease of moisture content from 76 to 7 percent (w.b.).
E. Velayati; B. Emadi; M. Khojastehpour; M. H. Saeidirad
Abstract
In order to enhance the mechanization level of harvest and post-harvest operations of Berberis fruit, as one of the major and local crops of south Khorasan province, some of its physical properties were investigated. Different dimensions, geometrical mean diameter, sphericity, surface area, mass of thousand ...
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In order to enhance the mechanization level of harvest and post-harvest operations of Berberis fruit, as one of the major and local crops of south Khorasan province, some of its physical properties were investigated. Different dimensions, geometrical mean diameter, sphericity, surface area, mass of thousand fruit, true density, bulk density, porosity, static coefficient of friction and the repose angles were determined. The properties and the effect of moisture content on them were studied by the completely randomized designs statistical method. Analysis of data indicated that the change of moisture content caused significant difference (P
