دکتر ایمان احمدی

The role of animal husbandry in general and dairy industries in particular has been proven in the national economy of the countries. In spite of the fact that only 4.5% of heavy livestock utilization is through dairy industry, it produces 32% of meat and 58% of milk requirements of Iran; therefore, recognition of Iran's dairy industry and planning to increase production capacity of it is essential in dairy industry farms. The aim of this study was to compare dairy industry farms of Iran provinces using the supplied data of Iran Statistic Center in 2015. The economical indicators used in this research were profit per capita, and profit to cost ratio of dairy industry profession, the portion of dairy industry employment from total employment of Iran provinces, and technical efficiency of dairy industry farms. After calculating the economical indicators using the Excel software, the geographic scatter map of the economical indicators was plotted using the t-map package of R software. The main result showed that using the combined equal weight four-factor criterion, Semnan, Alborz, Zanjan, Charmahal & Bakhtiari, and Yazd provinces had better performance compared to the other provinces. Therefore, because the pioneer provinces have experienced better performance in the same economical situation, the other provinces can improve their position after performing modifications in the management of dairy farms.

According to FAO, gherkin and cucumber have been cultivated in about 2.23 million hectares of farmlands around the globe, and about 78000 hectares of Iran agricultural fields have been devoted to gherkin and cucumber cultivation. However, large amounts of the cucumber seeds required in Iran have been imported from abroad. Fortunately, some Iranian agricultural companies have been focused on seed production recently. Therefore, there is an opportunity to develop seed production equipment such as seed extracting machines.There are two types of cucumber seed extractors: bulk seed extractor and single fruit extractor. The bulk seed extractor is suitable for extraction of large amounts of seed on the farm, while the single fruit extractor is suitable where seed production is limited to greenhouse seed-producing facilities which are mostly used for controlled pollination of the crop.Due to the high price of imported seed extractors, especially after increasing the price of foreign currencies, production of these machines within the country is economically rational; therefore, the aim of this research is to develop and evaluate a single fruit cucumber seed extractor for small and medium-size seed-producing greenhouses.

The cucumber seed extractor was designed semi-automatically. The criteria for designing the machine were as follows: 1- usage of the single fruit seed extraction method, 2- the possibility of simultaneous usage of two operators, 3- automatic discharge of the extracted seeds, 4- the possibility of the height variation of the machine, 5- the possibility of the emergency shutdown of the machine, 6- the possibility of the angular velocity variation of the machine helix.The working element of the machine was the rotating helix that can extract the fruit seeds and leave the fruit's outer skin mostly intact for easy disposal of fruit remains from the greenhouse. A 1 hp, 3 phase electric motor was used to drive the machine via the belt and pulley transmission system. For the smooth start and stop of the machine, and the possibility of angular velocity variation of the machine helixes, an electronic driver was used for the motor.To design the machine helix, the dimensions of the examined cucumber were measured first (i.e., cucumber length and diameter); then, according to the physical and mechanical properties of the fruit, the prime mover and transmission system of the machine was designed. Finally, the fabricated machine was evaluated using some mechanization criteria.

Some of the results are as follows:The total torque required to drive the machine was 3.394Nm.The electric motor power should be higher than 0.284hp; furthermore, in order to have a wider angular velocity span for the rotating shaft, a 1hp electric motor was installed on the machine.The diameter of the rotating shaft was calculated to be 15mm.The seed extracting machine could be used instead of 15 workers of the manual seed extraction method.The rate of seed extraction using the machine was 30781 kg ha-1.The efficiency of seed extraction using the machine was similar to that of the manual method.The emergence percentage of seeds obtained by the machine was similar to that of the manual method.The amount of crop calculated from the concept of economical break-even point was 7 tons.

In this study, an apparatus for mechanized extraction of cucumber seed was designed, fabricated and evaluated. The working element of the machine is the extractor helix that is rotated via the belt and pulley transmission system, which is activated using a 1 hp, 3 phase electric motor. For smooth start and stop of the motor, as well as the possibility of angular velocity variation of the machine helix, the motor was equipped with an electronic driver. Utilizing an emergency shutdown switch, the machine can be protected from unforeseen emergency situations. After using the machine for 6 months, it was recognized that strengthening the extractor helixes was necessary. According to the results of this study, using the machine led to 15 person reduction in the labor needs of the manual cucumber seed extraction method. Moreover, the amount of crop calculated from the economical break-even point was 7.7 tons.

The aim of this study is to design, fabricate and evaluate a new type of up-cut rotary tiller and to develop correct formulas to estimate its torque and draft force using the laws of classical mechanics. In order to verify the model, a real-sized prototype of the rotary tiller was tested. It was hypothesized that four processes are involved to create the rotary tiller torque, namely soil cutting, soil lifting, soil-metal friction, and soil velocity. Furthermore, it was assumed that the horizontal components of soil cutting and soil-metal friction forces create the required draft of the machine. Based on these hypothesizes, mathematical formulas were developed to calculate torque, and draft requirements of the machine. To facilitate performing necessary calculations, the developed formulas were entered in a worksheet of the MS Excel software. According to the results of this study, the average experimental draft and torque of the machine tilling a silty clay loam soil were 16.8 N and 12.8 Nm, respectively. Furthermore, the average theoretical draft and torque of the machine were 13 N and 11.8 Nm respectively. These promising results can be considered as the accuracy check of the formulas developed herein.

Measurement of the draft force exerted from agricultural machineries to the tractor and the calculation of the implement power requirements is important for agriculturalists in terms of machine design and tractor-machine matching . Therefore, studies about this issue have been started from the 1950’s. Zoerbet al.,(1983) claimed that the first dynamometers have been made of spring and in reality, users had difficulties reading these dynamometers gauge due to the quick variations of the gauge pointer. Therefore the second stage was the development of the hydraulic-type dynamometers in which the oil pressure inside the hydraulic cylinder-piston set installed between machine and tractor that can be readable with a bourdontube gauge was considered as its indicator. From the first years of the 1960’s development of the strain-gauge pull-type dynamometers started.
In this study, design, fabrication and evaluation of a pull-type tractor dynamometer is considered that can be used to measure and store tractor forward velocity, and horizontal component of draft force exerted from wheel-type towed implements to the tractor. Therefore, drawbar power needed to pull the machine through the soil can be calculated. This dynamometer can also be utilized to measure three-point-hitch implement’s draft force and power requirements in condition that the RNAM (1983) method was used. In addition to measure the tractor velocity with a GPS receiver instead of a fifth wheel, the other particular issue about this dynamometer is that a remote controller is used to order data acquisition commands such as starting, ending, pausing and time zeroing in the process of data gathering.
In this study an S-type strain gauge load cell (model: SS300) and a GPS receiver (model: Micro GPS antenna AGM-10 NEO-6-M-0-001 ublox AG board) were utilized to measure the draft force and forward velocity, respectively. To calibrate the load cell sensor, in an iron material selling store, the load cell was placed between an external force with a known value and roof-type load lifter by steel cables, and external loads with the value of 1-5 ton applied to the load cell in ascending and descending order. In each loading stage, the system and measuring apparatus outputs were booked. After drawing the x-y scatter chart of paired values (system output, measuring apparatus output), regression equation between these two variables were obtained that can be utilized to calibrate this part of the system. Above-mentioned method was used to calibrate the velocity measuring part of the dynamometer with a difference that real velocity was used instead of external load and velocity output was used instead of the load cell output. After performing the calibration of the system, the developed dynamometer was utilized to measure the draft force and power requirements of a three-point-hitch moldboard plow using the RNAM method. Finally, the obtained results were compared with the other researcher’s results, and the ASAE prediction of the draft force of a moldboard plow.
According to the results of this study, the estimated equation and its coefficient of determination for the calibration of the load cell sensor were , and respectively, and the estimated equation and its coefficient of determination for the calibration of the velocity were , and respectively. Moreover, according to the results of the field tests, draft force and the power requirements of a three-bottom moldboard plow in a silty clay loam soil with the forward velocity of was measured to be , and , respectively, that were in agreement with other studies. Furthermore, the draft force results of this study, and other studies were in the range of of the which is the moldboard plow draft prediction according to the ASAE standard.
This study suggests that with the aid of the RNAM method, and the developed dynamometer, the draft force and power requirements of the tillage implements can be calculated. These results can further be utilized to match the implements with the tractor or to design new tillage implements.

Cumulative effect of transmitted vibrations to the tractor driver not only leads to driver health problems, but also reduces the driver working efficiency. Tractor suspension system is one of the methods which is employed to lower the level of transmitted vibrations to the driver. In this study the design and performance assessment of a semi-active suspension model of tractor cabin was considered. Tractor full vibration model was developed first, and subsequently a semi-active ON-OFF damper model was designed. The examination of the model indicated that doubling the piston area and the volume of hydraulic accumulator air chamber, led to 39% increase and 31% reduction of the resonance frequency of transmitted vibrations to the driver, respectively. On the other hand doubling the piston area and the primary air pressure of the accumulator, affected the RMS of transmitted vibration to the driver by 77 cm s-2 reduction and 66 cm s-2 increase, respectively. Moreover, the numerical comparison of the model outputs with and without activation of semi-active cabin suspension, while the model was stimulated with the same input function, led to 43% improvement in RMS acceleration of the transmitted vibrations to the tractor seat. Therefore, the designed semi-active suspension model of cabin was able to attenuate the level of transmitted vibrations to the tractor driver.

Yield monitoring is one of the essential steps in the implementation of precision farming. Yield maps derived from yield monitoring system, clearly show crop yield variations. Research reports on preparing hay and forage yield maps are fewer in number and extent than those on grain crop. In this research, a method was developed for estimating alfalfa hay yield from a map developed for a small square baler. To obtain the crop yield map, two series of input data are needed namely: location and crop yield. In this research, location of the baler in the field was determined through using a local coordinate system. Since hay into the square baler is gradually accumulated to form the bale, spatial measurement of the hay is done by calculating the fractional volume accumulation. This fractional volume is converted into mass, by using two bulk density scales: bulk density of the forming bale and average bulk density of total field bales. Results of this study revealed that the output of system's shaft encoders were linearly related to the number of shaft revolutions (R2>0.998). By using each bale bulk density to convert volume data into mass, the error of system's yield measuring section was reduced from 22/12% to 1/74%. The error of the coordinate determination system used for length measurement was lower than that of the regular GPS (4.01% versus 14.27%).