فهرست مطالب عباس همت

Relative water content (RWC) in plants is one of the most important biochemical parameters and its deficiency limits efficiency of photosynthesis and crop productivity. The scientific reports on using spectroscopy in detecting drought stress for sesame plants are very rare. In this study, the possibility of identifying water stress in two sensitive (Naz-Takshakhe) and resistant (Yekta) genotypes by predicting the RWC in sesame plants under water-stressed conditions using spectral indices was investigated. The developed spectral indices in the form of the ratio/difference of the reflectance derived from the leaf diffuse reflectance spectra, limited to the Visible-Near Infrared (Vis/NIR) region (400–1100 nm), were used. One hundred and fifty pots from each of the two genotypes were randomly divided into three equal groups. Pots were irrigated at soil water potential of −0.1 MPa (well-watered), −1.0 MPa (moderate-water stressed), and −1.5 MPa (severe-water stressed). The Vis/NIR spectra were then obtained from the leaves of each pot. Leaf RWC was also measured. In most cases, linear relationships between the RWC and the means of the three band reflectance spectra including: green (520 to 565 nm), red (580-760 nm) and near-infrared (760 to 900 nm), as well as normalized difference vegetation indices (NDVIs), and spectral ratios (SRs) extracted from the reflectance spectra were obtained. The results showed that the mean reflection of the red zone with the coefficients of determination of 0.80 and 0.78 and RMSE of 4.58 and 2.51, NDVI3 with the coefficients of determination of 0.80 and 0.79 and RMSE of 3.84 and 2.51, and also, SR with the coefficients of determination of 0.84 and 0.76 and RMSE of 3.40 and 2.66 for both “Yekta” and “Naz-Takshakhe” genotypes, respectively, provided the best results for predicting the RWC of the leaves. Therefore, the Vis/NIR spectroscopy is a fast, somewhat accurate and non-destructive method for detecting sesame water conditions. Under water-stressed conditions, more severe changes in the RWC of the “Yekta” genotype compared to “Naz-Takshakhe”, led to better performance of the reflectance spectral indices in estimating the RWC of the leaf in this genotype. The presented results can lead to the development of a reliable and portable tool for rapid and non-destructive detection of RWC of the sesame leaves.

Long boom sprayers as efficient and high-performance machines enable farmers to carry out crop protection within a reasonable period. Despite many pieces of research, heterogeneity in spray pattern due to boom vibration remains a major challenge. In the present research, the feasibility of adjusting spray angle through pressure variation in conjunction with spray rate control using a pulse width modulation (PWM) to accomplish desired spray pattern was investigated. Using acquired data from various technical tests, a program developed via LabVIEW software to control the spray pattern along with spray rate as a function of nozzle height. The conformity of mean operational pressures and target pressures was investigated using the Kolmogorov–Smirnov Test. A similar method was used to investigate the conformity of mean operational fan angles and target fan angles. Mean differences of operational pressures were almost insignificant in the whole range of measurement height. Therefore, it can be concluded that the height factor has no significant effect on the ability of the system to obtain the target pressure. Results also indicated that mean operational pressures are in conformity with target pressures. Distribution of the operational and target fan angles was significantly difference. Considering the existence of target pressure in the system and the inability of the system in providing the target fan angle, it is concluded that nozzle performance in creation the target fan angle was not perfect.

Shear strength is one of the critical properties of soil that affects the interaction of machine and soil. Wetting-drying cycles change the structure the soil (due to frequent surface irrigation) and affects the shear strength parameters of the soil. Therefore, the effect of this process on the shear strength parameters of coarse-textured soil (sandy loam) is studied. In this study, large soil samples were prepared and some of them were subjected to 5 wettingdrying cycle. After that, the large soil samples with/without wetting and drying cycles were compressed under three loads (0, 100 or 200 kPa) at two water contents (0.9 plastic limit; PL and 1.1PL). Then three samples were prepared for direct shear tests. The results showed that the increase in water contents will increase bulk density and cohesion, and reduce the internal friction angle. Compressing the soil after wetting and drying process resulted in an increase in bulk density and cohesion, and reduction in internal friction angle. These changes were due to clay particles mobility and sedimentation among larger particles as well as developing water films among aggregates during wetting.

Power consumption and threshing efficiency are important parameters in the mechanization process. In this study power consumption and threshing efficiency are modeled with Artificial Neural Network (ANN) and after that optimization operation point for the rubber tooth threshing unit was defined. Independent parameters included the threshing cylinder speed (TCS), the distance between the threshing cylinder and concave or threshing space (TS) and moisture content (MC). Azargol variety was used to evaluate the threshing unit. The tests were performed at 3 TCS levels (280, 380 and 480 rpm), 2 TS levels (8 and 10 cm) and 2 MCs of sunflower head proportional to crop condition (20 and 45% wet basis). Results of analysis of variance show that the effect of TCS, MC, and TS on power consumption are significant and the effect of MC and TS are not significant on the threshing efficiency but the effect of TCS is significant on it. with increasing in TCS, MC, and TS, power consumption was increased. But threshing efficiency was increased just with increasing in TCS. After defining the ANN model the optimal operation point for minimize power consumption and maximize threshing efficiency was determined that it was 10, 600 and 11.5 for MC, TCS and TS respectively.

Determination of physical and mechanical properties of agricultural and horticultural crops is one of the most important parameters in design and manufacture of the operation machines. Determination of the effect of static and dynamic forces on Cherry Plum fruit during storage and transportation processes is very necessary for engineering. In this study, the physical properties of the Cherry Plum (including dimensional parameters and weight) and mechanical properties (including pressure test, punch test, and cyclic test) were measured at two levels of big and small sizes. The regression and ANN models based on physical properties data were defined and used to estimate the weight and volume of the fruits. The ANN model was the best model for estimating the fruit volume with 0.96 regression coefficient but it didn’t have a acceptable performance in estimating the fruits’ weight. The parameters of force and displacement, maximum stress at the breaking point, the elastic modulus in Hertz methods and Bosensky theory, the crust and mantle punch forces, the minimum stress based on Bosinskio theory, the distribution of vertical, horizontal and shear stresses in depth and surface in the failure point and etc were calculated based on the data of the mechanical properties. The results showed that due to the differences in the thickness of the mantle, the force absorption capacity in the big fruits was larger than the small ones. The results of comparison between the convex jaw and flat jaw in the compression tests showed that the fruits placed on the floor were more exposed to damage. The behavior of the stress distribution at the failure point showed that the horizontal stress would dictate the rupture in the fruits.

Harvesting is one of the most important field operations in sunflower production. Seed damage and low separation efficiency are the top concerns of harvesting sunflower. In this study, a threshing cylinder with rubber teeth and a concave for harvesting sunflower were designed and evaluated. The variable parameters were threshing cylinder speed (TCS), threshing space (TS) and moisture content (MC) of sunflower head. Azargol variety was used to evaluate the threshing unit. The tests were performed at three cylinder speed levels (280, 380 and 480 rpm), two threshing spaces (8 and 10 cm) and two moisture content of sunflower head based on the crop condition (20% and 45% wet basis). An ANN model was developed to predict the amount of materials in each part of the concave. Results showed that the sunflower seeds had no damage during the threshing process and the presented model could predict the amount of materials in each part of the concave with a regression coefficient R2=0.95. Based on the ANN model, with a decrease in MC and TS, and an increase in TCS, the separation efficiency was increased. Furthermore, optimal parameters for the threshing unit which were suggested by Design Expert software to maximize the separation efficiency were 18% w.b, 450 rpm and 10.5 cm for MC, TSC, and TS, respectively and in this condition separation efficiency was determined to be 94.92%.

The in-transit vibrations caused by uneven roads have a significant effect on mechanical damage of agricultural products. Olive (Olea europaea L.) fruit is one of the sensitive fruits to mechanical bruising. In this study, the effects of frequency and acceleration of simulated in-transit-vibration using a vibrating table were investigated on mechanical damage of two olive cultivars. The experiments were conducted using a factorial experiment in a completely randomized design with 3 replications. The factors included vibration accelerations (0.3g, 0.5g and 0.7g), vibration frequencies (5, 7.5 and 10 Hz) and cultivars (Conservolea and Roghani). The effects of frequency and acceleration on the mechanical damage of olive fruit were significant at probability level of 1%. Increasing vibration frequency and acceleration led to first increase and then decrease in mechanical damage. The effect of cultivar on mechanical damage was not significant. The frequency of 7.5 Hz had the most mechanical damage for both cultivars; therefore, it should be controlled during transportation. The combination of 7.5 Hz and 0.5g for Roghani and 7.5 Hz and 0.7g for Conservolea caused the most mechanical damage to the fruit.

The third wave of cognitive behavioral therapy (CBT) including acceptance and commitment therapy (ACT) embraces new approaches and methods potentially capable of addressing complex cases of substance abuse. It seems that the third wave of (CBT) emphasizing mindfulness and psychological resilience are effective in the rehabilitation of addicts undergoing methadone treatment.The present study intended to assess the effectiveness of group therapy based on acceptance and commitment in reducing the obsessive-compulsive use of substance, anxiety and depression of addicts under methadone treatment. In this quasi-experimental study, the statistical population included all addicted men who received methadone treatment in Zanjan in 1983-94. A sample of 30 patients was selected through convenience sampling & randomly assigned into two groups, intervention and control. The intervention group participated in 8 sessions of 90-minute group therapy based on acceptance and commitment. Obsessive-compulsive use of substance and anxiety/depression questionnaires were completed in the form of a pre-test, a post-test and a quarterly follow-up period in both groups. Group therapy based on acceptance and commitment effectively reduced the obsessive-compulsive use of substance, anxiety and depression (P <0.05).The effectiveness of this intervention in increasing physical health was not statistically significant (P> 0.05). The effect of group therapy based on acceptance and commitment was substantial in comparison to the control group in the post-test phase regarding the obsessive-compulsive use of substance (1.04), anxiety (1.63) and depression (1.6), furthermore, these effects remained stable over a quarterly follow-up period. The present study showed that acceptance and commitment therapy is effective in decreasing obsessive-compulsive use of substance, anxiety and depression.Therefore, acceptance and commitment therapy can be used as an effective intervention for psychological disorders associated with drug abuse in methadone-treated patients

In this study, a two-ring capacitive sensor mountable on multiple-tip horizontal penetrometers has been developed. The size and shape of the electric field around the sensor was estimated to ensure that the sensor fields are not interfered with the adjacent probes of the multiple-tip penetrometer using finite element. The sensor function was then evaluated at different levels of volumetric moisture. The maximum radius of the soil located in the sensor’s electric field is 30 mm in the wetted soil. So the usage of the sensor in combination with the penetrometers at distance of 10 cm from each other would not cause the interference of the electric fields of the sensors. Increasing volumetric moisture reduces the output voltage of sensor (R2=0.91). The developed capacitive sensor is a suitable devise for measuring soil moisture in the range of 0-PL which can be used to measure simultaneously resistance and soil moisture in several depths independently in combination with multiple-tip horizontal penetrometers.

The olive fruit (Olea europaea L.) is so sensitive to impact like many other crops that would lead to mechanical damage and bruising which reduce the quality of it. The olive fruit damage includes a brownish bruise at the bruised location. Most mechanical impact damage occurs during harvesting, handling and transportation. Bruise sensitivity of two common olive cultivars in Iran (cv. Roghani and cv. Conservolea) was studied by free fall method because of development of the area under olive cultivation in Iran, and necessity to mechanical harvest in near future.
Two cultivar of olive fruit named Conservolea and Roghani were collected from Research Orchard of Horticultural Department of Isfahan University of Technology. A free-fall device was designed and built to accomplish an impact experiment which included a load cell monitoring system to measure impact force. The effect of cultivar, height and mass were studied in a factorial experiment. The factors consisted of two cultivar, height at five levels, and mass at three levels with 10 replications. The experiments were performed according to completely randomized design. The effect of impact force and absorbed energy was also studied for the two cultivars. The dimensions of bruising was measured 24 hours after the tests by a caliper with an accuracy of 0.01 mm. The bruising area and volume was calculated assuming the elliptical model for the bruised region. Experimental data were subjected to analysis of variance (ANOVA). Mean comparison was performed based on least significant difference (LSD) test with.
For both cultivars the bruising occurred under the skin and near to the stone. This could show the effect of stone at bruising. The shape of bruised region was elliptical in cv. Roghani and spherical in cv. Conservolea. The bigger stone index and the lower flesh width of cv. Roghani might be one of the reasons of more volume of bruising in this cultivar. This variety could be due to less sphericity in cv. Roghani than cv. Conservolea. The distribution of bruising was more in Roghani cultivar since it had more oil and less water content that might led to more bruising distributed under impact condition so the volume of bruising was more than Conservolea cultivar. The effects of cultivar, height and mass were significant on area and volume of bruising. Increasing height and mass significantly resulted to increase the area and volume of bruising for both cultivars. The bruise area and volume were significantly higher in cv. Roghani. This could be due to differences in physical properties of the cultivars. Roghani cultivar had a higher pit/flesh ratio in comparison with Conservolea cultivars that could contribute to more area of bruising in this cultivar. Increasing the force and energy led to increase in bruise volume for both cultivars. In cv. Roghani, despite the lower levels of force and energy, the bruise volume was more than cv. Conservolea. The reason of lower energy and force in cv. Roghani might be as a result of lower mass than cv. Conservolea.
The results showed that the effects of independent variables were significant on the volume and area of bruising so that, increasing height and mass increased the volume and area of bruising. The Roghani cv. was significantly more sensitive to bruising compared to Conservolea cv. The energy and force levels were higher in cv. Conservolea since it was heavier than cv. Roghani while the volume of the bruise was more in cv. Roghani. This might be due to the lower sphericity and flesh/pit ratio in cv. Roghani. The shape of mechanical damage which was appeared with a brownish bruising on olive tissue was related to the geometric shape of the fruit i.e. for cv. Roghani and cv. Conservolea the bruising was elliptical in and spherical just like the geometric shape of the cultivars.

Today in the third wave of psychotherapy, it is claimed that individuals with cognitive flexibility, awareness, and acceptance of thoughts can modify their feelings and behaviors. The purpose of this study was to determine the effectiveness of group therapy based on acceptance and commitment in the reduction of craving and the improvement of quality of life in addicts receiving methadone treatment.
In this quasi-experimental study, the statistical population includes all male addicts receiving methadone treatment in Zanjan in 2015-2016. A sample of 30 subjects was selected through convenience sampling and later they were randomly assigned to intervention and control groups. The intervention group participated in 8 sessions of 90-minutes group therapy based on acceptance and commitment. Craving questionnaires of Franken et al. (2002) and quality of life (SF-36) were conducted in the form of pre-test, post-test and a quarterly follow-up period in both groups.
Group therapy based on acceptance and commitment could effectively reduce craving and increase mental health (P 0.05). The effects of group therapy based on acceptance and commitment on post-test craving and mental health in quality of life were significant in comparison to the control group and these effects remained stable over a quarterly follow-up period.
The present study showed that acceptance and commitment therapy is effective in decreasing craving and improving mental health.

IntroductionThe compaction of soil by agricultural equipment has become a matter of increasing concern because compaction of arable lands may reduce crop growth and yield, and it also has environmental impacts. In nature, soils could be compacted due to its own weights, external loads and internal forces as a result of wetting and drying processes. Soil compaction in sugarcane fields usually occurs due to mechanized harvesting operations by using heavy machinery in wet soils. Adding plant residues to the soil can improve soil structure. To improve soil physical quality of sugarcane fields, it might be suggested to add the bagasse and filter cake, which are the by-products of the sugar industry, to the soils.
When a soil has been compacted by field traffic or has settled owing to natural forces, a threshold stress is believed to exist such that loadings inducing lower than the threshold cause little additional compaction, whilst loadings inducing greater stresses than the threshold cause much additional compaction. This threshold is called pre-compaction stress (σpc). The σpc is considered as an index of soil compactibility, the maximum pressure a soil has experienced in the past (i.e. soil management history), and the maximum major principal stress a soil can resist without major plastic deformation and compaction. Therefore, the main objective of this study was to investigate the effects of wetting and drying cycles, soil water content, residues type and percent on stress at compaction threshold (σpc).
Materials and MethodsIn this research, the effect of adding sugarcane residues (i.e., bagasse and filter cake) with two different rates (1 and 2%) on pre-compaction stress (σpc) in a silty clay loam soil which was prepared at two relative water contents of 0.9PL (PL= plastic limit, moist) and 1.1PL (wet) with or without wetting and drying cycles. This study was conducted using a factorial experiment in a completely randomized design with three replications. A composite disturbed sample of topsoil (0–200 mm deep) of a silty clay loam soil was collected from Isfahan province (32 31.530 N; 51 49.40E) in center of Iran. The mean annual precipitation and temperature of the region are about 160 mm and 16 C, respectively. Sugarcane residues (bagasse and filter cake) were obtained from the sugarcane fields in Ahvaz, Khuzestan province (Iran). The samples were air-dried and passed through a 2-mm sieve. Soil treated by bagasse and filter cake in different rates was poured and knocked lightly into cylinders with diameter and height of 25 and 8 cm, respectively. Large air-dry disturbed soil samples were prepared and some of them were exposed to five wetting and drying cycles. Finally, the soil surface was covered by a plastic sheet and was left overnight in the laboratory (for 24 hours) to enable the moisture to equilibrate. The loading tests were performed the next day. The pre-compaction stress was determined by plate sinkage test (PST). The loading test for PST was performed using CBR apparatus. The compression for PST was continuous at the same constant displacement rate of the CBR (i.e. 1 mm min-1). Determination of the σpc was done using Casagrande’s graphical estimation procedure (Casagrande, 1936) in a program written in MatLab software.
Results and DiscussionThe results showed that σpc was significantly decreased by adding residues to the soil at both water contents, and with/without wetting and drying process. For untreated treatments (control), the σpc decreased with increasing water content. Although σpc decreased with adding the residues to the soil, however, the effect of residue types and percentages and soil water content on σpc was not significant for the soil samples treated with residues.
ConclusionsIn order to prevent re-compaction of the soil and improve its structure, it is suggested that traffic control system with permanent routes for the movement of machinery to be used in sugar cane plantations and the residues (after desalination) to be added into strips that are placed under cultivation.

Introduction Soil compaction is a serious concern in modern agriculture. Field traffic using machines with high axle loads is likely to compact the soil below the plough layer. Compaction of the subsoil should be avoided since soil productivity is at risk of being reduced, and because the effects are very persistent, perhaps even permanent. Precompression stress is widely applied as a border between elastic and plastic soil deformations under stress application. As long as the stress does not exceed the precompression stress, soil deformation is expected to be recoverable after the removal of stress (i.e. passage of the tire). The precompression stress is conventionally determined using the standard procedure of Casagrande from the log stress – void ratio curve resulting from confined uniaxial compression of intact soil samples taken at the field. With advances in the technology of precision agriculture, site specific management of machinery traffic is under focus by researchers. Field mapping of soil precompression stress would allow for site specific modifying the machine parameters (e.g. the tire inflation pressure) to control the applied stress below the precompression stress. For example, where the soil moisture is high, a decrease in tire inflation pressure increases the soil-tire contact area and thus decreases the severity of stress propagation in soil. However, the conventional method of estimating the precompression stress is time-consuming, labor intensive thus not suitable for mapping applications. Horizontal penetrometer is a popular device for on-the-go measuring of soil strength. Horizontal penetrometer resistance is an attractive measurement because it is relatively simple, fast and cheap, can be carried out on-the-go, thus yielding spatial information with a high resolution. A multi-tip horizontal penetrometer would also allow for discrete-depth measuring the soil strength. As penetrometer resistance and precompression stress are both measures of soil strength, it was hypothesized that they are highly correlated. Therefore, the relationship between precompression stress (σpc) and horizontal penetrometer resistance (PR) was investigated in a wide range of soil textures. This would suggest an alternative for on-the-go measurement of σpc for field mapping and site-specific management of soil trafficability.
Materials and Methods Field measurements were conducted in different soil textures in Switzerland. The clay content of the soils varied from 189 to 584 g kg-1. Horizontal penetrometer resistance was measured at 0.25 m depth at a traveling speed of 0.25 m s-1. Cylindrical core samples were taken at the local minima and maxima of PR along the transects. Cone index measurements were also performed to a depth of 0.5 m at the points of core samples. The samples were subjected to stepwise compression stresses by an Oedometer and the resulting deformation was recorded. The void ratio was calculated with particle density and bulk density at the end of each stress step. The precompression stress was estimated at the point of maximum curvature of log stress- void ratio with fitting Gompertz function. Correlation and regression analyses were performed in SAS software.
Results and Discussion The results showed that the Gompertz function explains well the void ratio versus log of stress for different soil textures. The Gompertz parameters were characterized with respect to soil physical characteristics. Precompression stress decreased with increasing soil moisture, soil clay and organic matter content. A relatively strong correlation was found between σpc and PR (R2= 0.47, RMSE= 15.4 kPa) which was significantly improved (R2= 0.59, RMSE= 13.7 kPa) with the effect of soil water content. The high scatter of the relationship between precompression stress and horizontal penetrometer resistance was discussed to be likely due to the difference between the soil failure mechanisms around a penetrating tip and under uniaxial compression. A comparison of different compaction tests (e.g. semi-confined and plate sinkage) with PR may suggest stronger correlations. A strong correlation (R2= 0.6) was also found between PR and cone index (CI). CI was found to be larger than PR for all the soils.
Conclusion It was concluded that the soil compaction characteristic (log stress versus void ratio) is strongly governed by the soil initial void ratio with an increase of precompression stress with decreasing the initial void ratio. In the range of variations tested, the relationship between PR and σpc was not affected by soil texture (clay content). The study suggests that measurement of PR can be a fast alternative for mapping of soil precompression stress by compensating for the effect of soil moisture (by e.g. a dielectric sensor). therefore, a combined horizontal penetrometer needs to be employed.

In this study, a cylindrical Bolling probe was developed and evaluated for measuring stress in soil under tire traffic. The probe consists of a silicon rubber head for sensing the soil stress, a PVC tube for transferring the liquid pressure, a digital pressure sensor and a syringe for filling the probe with water and adjusting the initial inclusion pressure. A tank with pressurized air was used for laboratory testing of the probe. The probe head was put into the tank and with sealing the slits, the probe was tested at four initial inclusion pressures of 25, 50, 75 and 100 kPa. The relationship between Bolling and air pressures was investigated. The results showed perfectly linear relationships between the air and Bolling pressures at different initial inclusion pressures. The difference between the Bolling pressure and initial inclusion pressure versus air pressure slightly (

Iran is one of the main producers of kiwifruit in the world. Unfortunately, the sorting and grading of the kiwifruits are manual, which is a time consuming and labor intensive task. Due to the lack of appropriate devices for sorting and grading of kiwifruit based on the quality parameters, only 10% of total production is exported (Mohammadian & Esehaghi Teymouri, 1999).
One of the main quality attribute for evaluating the kiwifruits is weight. Based on the standards, the minimum weight for an excellent kiwifruit is 90 g, while these values for the first and second classes should be 70 and 65 g, respectively (Abedini, 2003). Therefore, developing a device for fast weighing of fruits in the sorting lines can be useful in packaging, storage, exporting and distributing kiwifruit to the consumer markets.
In the past, the mechanical-based systems were commonly used for online weighing of the agricultural materials, but they did not lead to the promising accuracy and speed in sorting lines. Today, electrical instruments equipped with the precise load cells are substituted for fast weighing in the sorting lines. The dropping impact method, in which a free falling fruit drops on a load cell, is one of the suitable techniques for this purpose.
Different studies have addressed the application of dropping impact for fast weighing of agricultural materials (Rohrbach et al., 1982; Calpe et al., 2002; Gilman & Bailey, 2005; Stropek & Gołacki, 2007; Elbeltagi, 2011). The aim of this study reported here was to develop an on-line system for fast weighing of kiwifruit and compare the accuracy of different methods for extracting the weight predictive models.
Sample selection: A total of 232 samples with the weight range of 40 to 120 g were selected. Before conducting the main experiments, the weight and dimensions of the sample were measured using a digital balance and caliper, with the precisions of 0.001 g and 0.01 mm, respectively.
Impact measuring system: The impact signals of kiwifruits in an online situation were acquired using a system, including conveying and ejecting unit, a load cell and data acquisition unit (Fig.1). The load cell was a single point load cell with 5 kg capacity. The load cell was connected to the data acquisition unit (Fig.2) in order to record the impact signal of the device in time domain of 0-5 s.
Before performing the main experiments, the load cell was calibrated using 100, 200, 500 and 1000 g standard masses. All the tests were carried out on three different forward speeds of conveyor, including 1, 1.5 and 2 m s-1 in order to obtain the optimum forward speed.
Data Analysis: In this study, two different methods were applied to build the weight predictive models. In the first method, the main components of the impact signal, including the force value at the first peak Fp, time required to peak force Dp, and the impulse or area under the first peak Ip were calculated and used as independent variables to develop the weight predictive models. In the second method, the impact components were calculated for the 40 successive peaks. Multiple linear regression (MLR) analyses were used to correlate the independent (impact components) and dependent (weight) variables.
The weight statistical characteristics of the samples, including the maximum, minimum, average, standard deviation and coefficient of variability in total data, calibration and test sets are shown in Table 1. As depicted, almost the same range and variability were observed for calibration and test data sets, indicating the proper distribution of the samples.
Table 2 summarizes the results of simple and multiple linear regressions for predicting the weight from the signal components (Fp, Dp, Ip) of the first peak at different speeds of 1, 1.5 and 2 m s-1. As shown, at the forward speeds of 1 and 2 m s-1, the multiple regression models based on all three signal components, and at forward speed of 1.5 m s-1, the model based on the combination of Fp and Ip, resulted to the best prediction powers. Among different forward speeds, the forward speed of 1 m s-1 gave the best model with SDR value of 2.180. Fig.4 depicted the predicted versus true values of weight obtained from the best linear regression models using components of Fp, Dp, Ip, Fp-Ip, and multiple of the first peak of impact signal.
The results of simple and multiple linear regression for predicting the weight from the signal components (Fp, Dp, Ip) of the first forty peaks at different speeds of 1, 1.5 and 2 m s-1 are summarized in Table 3. The best models were obtained by multiple combination of all three impact signals at the forward speed of 1 and 2 m s-1, and combination of Fpi-Ipi (i=1,...,40) at 1.5 m s-1 speed. Compared with the first peak results, the accuracy of prediction reached to 84%, 60% and 52% at forward speeds of 1, 1.5 and 2 m s-1, respectively. The best results were obtained at a forward speed of 2 m s-1, in which the SDR reached to a satisfactory value of 2.857 by applying the Ipi (i=1,...,40) values. The predicted versus true values of weight obtained from the best linear regression models using components of Fp, Dp, Ip, Fp-Ip, and multiple of the first forty peaks of impact signal are illustrated in Fig.5.
The results of this study revealed that among different impact component, Ip was the best predictor of the kiwifruits weight. Moreover, the developed models based on impact components of the first forty successive peaks gave the best accuracy with respect to the first peak components.

Bagasse and filter cake are by-products of sugar factories which are full of nutritional ingredients and organic matters. Mechanical characteristics of the soil are considered very important in order to determine the allowable stress for preventing soil compaction. One of the important indices is pre-compaction stress which can be used as a criterion for load support capacity of the soil. In this research, the soil samples with wet bulk density 1.5 g cm-3 were prepared; then a plate sinkage test (PST) was used to determine the soil pre-compaction stress (σpc). The effects of two types of sugarcane residues with two different rates (1 and 2%) at two water contents (WCs) of 0.9PL and 1.1PL (plastic limit) on soil σpc were studied. Results showed that σpc was significantly decreased by adding residues to the soil and also increasing WC. By adding residues to the soil at WC of 0.9PL, the load support capacity of the soil was decreased by 22.6%. In the residue-added treatments as compared to control, the σpc was decreased by more than 32% when the WC increased from 0.9PL to 1.1PL. When the WC increased from 0.9PL to 1.1PL, in the filter cake-treated soil, the susceptibility to compaction was increased. Consequently, by adding residues to the soil and changing the water condition from moist to wet, the resistance of the soil to compression was remarkably reduced.

In order to decrease water consumption in agricultural sector, deficit irrigation has been suggested. For preventing a heavy loss in crop yield, management of water stress is essential. Common methods for measuring plant water stress such as stomatal conductance are time-consuming and require specialized labor and a large number of measurement. Temperature of leaf or canopy surface can be an indicator of stomatal conductance or plant water stress. Canopy temperature is not only affected by stomatal conductance, but also with environmental conditions such as air temperature or vapor pressure deficit. Crop water stress index (CWSI) is recently proposed to solve these problems. By comparing the canopy temperature with two reference temperatures in crop water stress index, the effect of environmental conditions can be minimized. Thermography is a non-contact approach toward surface temperature measurement without interfering with plant activities. The general goal of this study was to obtain CWSI using thermal images and to evaluate the potential of this method for predicting the stomatal conductance. In order to achieve this goal, thermal images from olive trees under five deficit irrigation treatments with three replications were obtained. The results showed a significant (R2ADJ = 0.83) relationship between CWSI and the stomatal conductance

Apple is one of the most important horticultural crops of Iran. Its production in the country stands in the second place after citrus. Iran holds the fourth place in the world production of apples and gains a major share in the export of this product. Therefore, it is necessary to enhance the quantity and quality of the fruit in order to maintain and promote its position among the countries importing this product from Iran. Most of the mechanical damages to fruits and vegetables occur due to contact stresses under static, quasi-static and impact loading. To obtain stress distribution inside the fruit we can use finite element analysis. The aim of this study was to simulate the behavior of the apple as a viscoelastic body subjected to quasi-static loading and also to determine the failure criteria (maximum normal stress or shear stress) of apple flesh to estimate its susceptibility to mechanical bruising. In this study, Golab kohanz apple was used. Two samples were removed from each apple using a core sampler, one was used for uniaxial compression and the other was used for confined compression test using Instron universal tension and compression machine. Spherical indenter and parallel plate tests were performed in order to study apple susceptibility to bruising at four deformation levels (1, 2, 3 and 4 mm) and the bruise volume was then measured after 24 hours. Stress-strain curves were plotted and then, the elastic and viscoelastic properties were obtained. Then, by using the data obtained from apple properties, the apple was modeled in Abaqus software as spherical and cylindrical shapes with viscoelastic behavior subjected to quasi-static loadings. The normal stress distribution of the modeled apple in the shape of a cylindrical sample is shown in Fig. 4. The value of maximum normal stress was obtained (0.51 MPa) at the contact point of the loading plate with the sample. Experimental and modeled stress-strain curves are shown in Fig. 5. Up to the bio-yield point, the two curves are nearly matched; and beyond that point, there are some overestimations in the predicted stress values. The location and pattern of failure have often been used to explain the cause of failure in fruits. When specimens of fruit are subjected to a uniaxial compression, the failure often occurs the maximum shear stress plane. Failure patterns in the tested samples indicate that the failure occurs due to shear stresses. Another explanation that has been used by researchers for shear failure is the bruising position inside the fruit after loading. The position of bruising in most of the tested apples was a distance away from the apple surface (Fig. 7). According to the experiments results at the three deformation levels of 2, 3, and 4 mm, the maximum generated normal stress inside the apple was above the point of failure of the cylindrical samples. Based on the empirical results, the bruising was almost zero for the apples subjected to one or two mm deformation (Fig. 9a). The experimental value of the shear strength of the Golab kahanz apple was obtained to be 0.23 MPa. The maximum shear stress inside the modeled apple due to the two mm deformation was 0.195 MPa, which was lower than the shear strength of the apple. On the other hand, by applying three and four mm of deformation, the maximum shear stresses were obtained to be 0.24 and 0.26 MPa, respectively, indicating that the induced stress exceeded the shear strength of apple flesh; therefore, the bruising was observed in the flesh of these apples. The location of the maximum shear stress corresponds to the location of bruising in the tested samples as shown in Fig. 9b. According to the obtained results from the modeling in the finite element software, we can use this software in order to recognize and investigate the damages in agricultural products during different loading conditions (Harvesting, transportation, packaging and storage). In this work, Golab apple was considered as a viscoelastic material and its behavior under quasistatic loading was modeled using finite element method. Elastic, viscoelastic properties and shear strength of apple flesh were obtained and used in the simulation. Comparison of modeling and experimental results shows that the model simulates the behavior of apples during quasistatic loading well. The location of bruise occurrence in the flesh of tested apple and the location of maximum shear stress in the simulated apple was the same. Therefore, the maximum shear stress criterion can be used to estimate the susceptibility of apple varieties to internal bruising under quasistatic loading. Modeling of apple as a viscoelastic sphere in Abaqus software assuming constant bulk modulus could properly simulate apple behavior under quasistatic loading.

Considering soil compaction problem in sugarcane fields due to using heavy harvester and haulout equipment under unsuitable moisture conditions, this research aims to assess soil compaction in sugarcane fields located in DabalKhazaei Plantation unitofSugarcane Development and By-product Company, Ahvaz. Undisturbed soil samples from the furrow (wheel tracks) were collected for measuring soil water content and bulk density. Considering the changes in soil texture of sugarcane fields, for expressing the degree of soilcompactness, in addition to soil bulk density (BD), relative bulk density (BD divided by reference BD) was also determined. The change in soil mechanical resistance with depth was determined by a cone penetrometer. Results showed that most of soil BD values measured in the sugarcane fields were in the range of small root development scale (high limitation). Comparingthe calculated RBD values with optimum value (0.85), it was observed that most of the values were higher than the optimum values recommended for root growth. This shows excessivesoil compaction in the sugarcane fields. The values of cone indices measured in soil profiles indicated that most of the values were higher than either limiting (2 MPa) or critical (3 MPa) values for root growth. Therefore, for improving soil physical fertility and achieving sustainability in crop production, management of farm machinery traffic in sugarcane fields, especially at the harvest time, needs to be reconsidered.

About 60% of the mechanical energy consumed in mechanized agriculture is used for tillage operations and seedbed preparation. On the other hand, unsuitable tillage system resulted in soil degradation, affecting soil physical properties and destroying soil structure. The objective of this research was to compare the effects of three types of secondary tillage machines on soil physical properties and their field performances. An experiment was conducted in a wheat farm in Jouybar area of Mazandaran as split plots based on randomized complete block design with three replications. The main independent variable (plot) was soil moisture with three levels (23.6-25, 22.2-23.6 and 20.8-22.2 percent based on dry weight) and the subplot was three types of machine (two-disk perpendicular passing harrow, Power harrow and Rotary tiller). The measured parameters included: clod mean weight diameter, soil bulk density, specific fuel consumption, machine efficiency and machine capacity. The effects of treatments and their interactions on the specific fuel consumption, machine efficiency and machine capacity and also the effects of treatments on bulk density were significant (P<0/01). The bulk density decreased 15.3%, the specific fuel consumption increased 11.8%, whereas the machine efficiency and machine capacity increased and decreased with the decrease in soil moisture, respectively. The maximum value of the bulk density and machine efficiency were obtained by the use of rotary tiller and the maximum value of the specific fuel consumption and machine capacity were obtained by the use of power harrow. A criterion was defined for selecting machine type and moisture content for optimum condition. The results suggested power harrow working at soil moisture condition of 24.3% (based on dry weight).

Flood irrigation after planting induces wetting and drying cycles in arable soils. For this reason, the effect of this process on load-bearing capacity (pre-compaction stress; pc) of a fine textured soil (silty clay) was studied. In this research, large air-dry disturbed soil specimens were prepared and some of them were exposed to five wetting and drying cycles. Next, the large soil specimens with/without wetting and drying cycles were compressed under three preloads (0, 100 or 200 kPa) and then the centre section of the preloaded soil specimen was firstly submitted to a plate sinkage test (PST). Then immediately one cylindrical sample was cored for confined compression test (CCT). The results showed that for reconstructed soil samples without wetting-drying cycles, the predicted σ pc using PST didnt significantly differ from the applied preload. Therefore, the PST can be used to determine the load-support capacity of the tilled soils. In PST, with an increase in soil water content from 0.9PL to 1.1PL, the amount of over-prediction in σ pc decreased. However, wetting-drying process significantly increased over-prediction in σ pc at the same water content. Hence, soil compressibility does not simply depend on the actual soil water content but also on the previous history of water content changes (i.e., wetting-drying cycles).

efficiency was investigated during a 2-year period (2009-2010) in a silty clay loam soil in Tajarak Research Station (Kaboudarahang Township), Hamedan. The experimental design was a strip-plot within a randomized complete blocks design. The horizontal band, the irrigation water rate after flowering, included full and deficit irrigation (100% and 75% potato water requirement) and the vertical band, kind of inter-planting row tillage including 1- subsoiling to 30-35 cm soil depth, 2- chiseling to 20-25 cm soil depth, 3- sweeping to 5 cm soil depth and 4- no-till. During the growing season, soil mechanical resistance (cone index) in two stages and water infiltration into the soil were measured. At the end of the growth season (harvesting time), potato yield quantity and quality were measured. Result showed that the effect of inter-row tillage on soil mechanical resistance was significant. Subsoiling and chiseling had lower soil mechanical resistance and higher water permeability between treatments, respectively. The effect of inter-row tillage on potato yield was significant so subsoiling and chiseling had a higher potato yield between treatments, respectively. The effect of irrigation water rate on potato yield was not significant. The effect of inter-row tillage on water use efficiency wasn’t significant.

For planting fine seeds in cellular trays، an automatic pneumatic seeder was designed، constructed and evaluated. CATIA software was used to design and analysis the system parts of the seeder. Different parts of the seeder، including vibrating seed hopper، vacuum boom، seed picking nozzles، seed tube، pneumatic system and electronic control unit for automation of the seeder، were designed and constructed. The area of nozzle orifice was used to calculate the required pressure of nozzle tip. The seeder was evaluated using two sizes of trays. Experiments were performed with five replications and the error of planting the seeds in the 105 and 390-cellular trays were 1. 9 and 0. 46 percent، respectively. The time of planting for 105 and 390 cellular trays reduced from 20 min (for manual seeding) to 35 s and from 90 min to 160 s، respectively.

Agricultural soils are continuously under wetting and drying cycles during flood irrigation. Large air-dry disturbed soil specimens with dry bulk density (BD) of 1. 2 g cm-3 were prepared and the effect of wetting and drying cycles on compactibility of fine and coarse textured soils was studied. The large soil specimens with/without wetting and drying cycles were compressed under three preloads (0، 100 or 200 kPa) and then the small soil samples for water content and bulk density measurements were removed. The results showed that the wetting and drying process resulted in increase in an BD for both soils without applying any compacting load. This process resulted in soil susceptibility to compaction for coarse textured soils، whereas it increased the resistance to soil compaction for fine textured soils. Therefore، in fields with coarse-textured soils and under flood irrigation، are more sensitive to soil compaction at harvest traffic at both soil conditions as compared with the fine-textured soils. Therefore، with reducing contact pressure and axal loads the soil compaction could be prevented.

Wetting and drying induce stresses in soil which changes the physical structure of the soil. For this reason، the effect of this process on evaluating the methods for estimating the threshold of compactibility (load-bearing capacity، pre-compaction stress) of a coarse textured soil (sandy loam) collected from the fields of the Sugarecane and By-product Development Co. in Ahvaz province was studied. In this research، the plate sinkage test (PST) and confined compression test (CCT) methods were evaluated. Large air-dry disturbed soil samples were prepared and some of them were exposed to five wetting and drying cycles. After that، the large soil samples with/without wetting and drying cycles were compressed under three loads (0، 100 or 200 kPa) and then the centre section of the preloaded soil samples was firstly submitted to PST. Then immediately one cylindrical sample was cored for CCT. The results showed that for the soil samples without wetting and drying process، there was no significant difference between the applied load and the estimated values using PST method. However، for the soil samples under wetting and drying process، the obtained values were significantly greater than the applied loads. Therefore، for tilled soil، PST can be used as a quick method to determine the compression parameters of the soil in laboratory or in the field.