In this paper, the dynamics of multicellular chopper are considered. The model is described by a continuous time three{dimensional autonomous system. Some basic dynamical properties such as Poincar e mapping, power spectrum and chaotic behaviors are studied. Analysis results show that this system has complex dynamics with some interesting characteristics.

A new device was designed for chopping fodder and for its automation. To feed the fodder into the jaws of the chopper, a coupler curve of a four-bar mechanism was used. The most efficient and time saving method of selection of the coupler curve was identified, accordingly an Atlas of these curves, for the first time in Iran, containing more than 8000 items was produced. The device can be operated manually as well as by an electric motor. It is shown that the performance of the designed machine is 9 times better than the commonly used choppers.

A prototype of a straw chopper, equipped with a discharge system was designed and fabricated in the Department of Mechanics of Agricultural Machinery, University of Tehran, Karaj, Iran. To test for the effective performance of the machine, the effects of such parameters as: drum speed (at three levels of: 400, 540, and 800 rpm), screen size (at two levels: 2.5 and 4 cm), and number of blades on each flange (4 and 8 blades), on power requirement for particle size reduction, chopping capacity, and straw particle size distribution were investigated. Based on the results, with increase in drum speed, power requirement as well as threshing capacity increased. There was no significant difference observed between drum speeds of 540 and 800 rpm as regards particle size distribution, while a speed of 400 rpm resulted in longer particles, therefore a drum speed range of 540 to 800 rpm was recommended. With decrease in screen openings' size, the power requirements increased while the threshing capacity decreasing. Screen size of 2.5 cm led to finer particles. With an increase in the number of blades on each flange, the power requirements decreased while the threshing capacity increasing. Since there was no significant difference observed between the numbers of the two sets of blades as regards particle size distribution, it is recommended that 8 blades be installed on each flange. The power requirement can thus be reduced and the cutting capacity increased.

In this study, we aimed to design and make an electric forage chopper having a cylinder type cutterhead. In recent years, several models of forage chopper have been manufactured but each of these machines has had problems such as type of power supply system, type of cutting mechanism and feeding mechanism, lack of safety, etc. These problems were solved in this study. In the device that was manufactured in this research, feed rolls rotational speed, rotational speed of the cutting cylinder, blades’ helix angle and blades’ rake angle was adjustable. So, with these capabilities, these variables can be optimized for any kind of forage, and this information can be used to design and construct suitable machines for crushing any kind of forage. Alfalfa was used to test the machine, where its test matrix was determined using Response Surface Methodology (RSM) modeling method. The results showed that, on average, power requirements for chopping alfalfa was decreased from 12. 6 to 9. 7% by increasing the helix angle from 0° to 10° and from 10° to 20° , respectively. As rotational speed of the cutting cylinder increases from 500 to 800 rpm, the power used for chopping forage increases by about 56 W. In the conducted tests, maximum power requirements for chopping alfalfa was roughly equal to 200W, which was associated with 158. 5 rpm feed rolls rotational speed, 800 rpm rotational speed of the cutting cylinder, and helix angle of zero. Contrarily, minimum power requirements for chopping alfalfa was 114W which was related to 158. 5 rpm feed rolls rotational speed, 500 rpm rotational speed of the cutting cylinder, and 20º helix angle. Optimizing test results showed that the most suitable values for the feed rolls rotational speed, rotational speed of the cutting cylinder, and helix angle were 150 rpm, 677 rpm, and 9. 22º , respectively, provided that power requirements and particle size are minimized and device capacity is maximized.

For the ion beam analysis of insulating materials, we have investigated the design and calibration of an ion beam chopper. The chopper consists of a holder, a chopper plate, four photo sensors, a stepper motor, and an electronic control unit. The chopper plate was designed based on sharing an equal fraction of the ion beam between the chopper and the target. The situation of the chopper to the ion beam is controllable by using four photo-sensors around it. The time intervals in which the material is analyzed and the number of incident ions measured are determined via gate pulses governed by the sensors’ signals. The ion beam current was measured by charge integration at the chopper plate. We calculated the charge correction factors to eliminate the contribution of secondary electrons to the measurements. The measurements were done via Rutherford backscattering spectroscopy (RBS) analysis of a thin Au layer deposited on Si wafer with helium and proton ions in the energy range of 1-2. 2 MeV with a precision of less than 5%. The charge correction factors are independent of the ion beam current.

Considering the increasing population of the world and the lack of human food sources, it is very important to pay more attention to fodder plants that can indirectly supply human food. By using choppers, a large amount of fodder can be transported and prepared for anaerobic fermentation of fodder. In this research, a control mechanism has been proposed to change the angle of the knives on the cutting drum with a tangent plane on the circumference of the drum in order to change the distance between the knives and the fixed knife and change the length of the pieces. The mechanism was analyzed in SAM software, and then the three-dimensional model of different blade angle states was designed and analyzed in CATIA V5 R21 software. According to the obtained data, although the Von Mises stresses occur at the minimum angle of 22 degrees and the maximum Von Mises stress occurs at an angle of 16. 5 degrees, there is no significant difference in the amount of stresses. Therefore, this mechanism can be recommended for all the mentioned situations (angles). For 1600rpm rotational speed and 6083 N/m line force density the occurred Von Mises stress in 22 degree angle is lower than zero degree angle.

Introduction In most small and medium-size traditional animal farms, silage corn is chopped manually. In order to prepare appropriate chopper for small animal production firms, a small electrical powered chopper was designed and developed. Materials and Methods The machine consisted of different parts, including chassis, driveline, power transmission, feeding and cutting unit. To provide the power for cutting cylinder and feeding rollers, 3. 7 kW and 1. 5 kW electro-motors were selected and used, respectively. Power was transferred from electro-motors to the cutting cylinder and feeding rollers by pulley and belts. Feeding entrance area was 62. 5 cm2with theoretical capacity of 1. 13 kgs-1 and feeding unit power consumption of 0. 97 kW. The main parts of feeding and cutting units were analyzed by ANSYS Software. Silage corn was provided at harvest time from the Dashte-Naz, Sari province, and transported to laboratory, immediately. The effect of cutting blades speed (400, 550 and 700 RPM) and feed rollers speed (350, 400 and 450 RPM) on the chopper performance (cutting and feeding energy consumption, chopped corn length and machine capacity) were investigated. The results then analyzed using completely randomized design in triplicates. Results and Discussion Analysis of variance showed that the speed of cutting blades, speed of feeding rollers and their interactions had significant effect (p <0. 01) on the energy consumption of cutting blades and machine capacity. The effect of speed of feeding rollers was significant on the energy consumption of feeding rollers at 1% level of significance. Also, The effect of speed of chopping blades, speed of feeding rollers and their interactions were significant on the length of chopped corn (p <0. 01). Machine capacity increased by increasing in speed of chopping blades from 400 to 550 RPM and decreased by increasing from 550 to 700 RPM. Increasing in the speed of the blades at the moment of impact, caused to effectively cut the stem fibers before being compressed or bent. Increasing the speed beyond 550 RPM provided insufficient time for stem movement toward the blades and therefore, machine capacity decreased. By increasing the speed of feeding rollers, the consumed energy by cutting blades decreased and the energy consumption of feeding rollers, the length of chopped corn and the machine capacity increased. Since the machine capacity is depending on time, increasing in feeding rollers speed, decreased the time for chopping the feed stems resulted decreasing in machine capacity. Also, results depicted that the interaction between speed of cutting blades and feeding rollers had meaningful effect on the consumed energy by cutting blades. The maximum energy consumption was at the blade speed of 700 RPM and the feeding rollers speed of 350 RPM, and the minimum energy consumption was at the blade speed of 400 RPM and feeding rollers speed of 450 RPM. The maximum and minimum length of chopped corns was obtained at the blade speed of 400 RPM and 700 RPM, respectively and correspondingly at the rollers speed of 450 RPM and 350 RPM, respectively. The maximum capacity of the machine was obtained at the blade speed of 550 RPM and rollers speed of 450 RPM. Conclusions Since the length of the chopped corn for animal feeding is 20-30 mm, the optimum speed of cutting blades, minimum energy consumption and maximum machine capacity was obtained as 550 RPM and the optimum speed of feeding rollers was at 400 RPM. For feeding high yielding dairy cows, goats and sheeps that need smaller sized forage, it recommended that feeding rollers speed to be adjusted at 350 RPM. At the same speed, the mean length of chopped corn was 8-19 mm.

In this study, the design and construction of the neutron velocity selector were investigated. Theoretical and experimental studies have shown that it is preferable to construct the blades and the main shaft of the device from carbon fibers to reduce weight, prevent imbalance, and improve performance at high speeds. After designing the other components of the device, manufacturing the parts, and assembling the device, the vacuum system was tested, measuring a vacuum pressure of 3×10-2 millibars.   In the next phase, the device was mechanically tested at various speeds between 3000 and 11000 rpm, confirming the mechanical stability of the device. The measurement of selected thermal neutrons was carried out using neutrons from a 252Cf source. The experimental results show that this device is suitable for measuring the energy of neutrons in the range of less than 0. 001 eV. This device requires a high-speed motor with a rotational speed of approximately 35, 000 rpm and a high-resolution encoder to allow the passage of thermal neutrons with an energy of 0. 025 eV, in order to reduce the error in time-of-flight measurements to an acceptable level.

Neutron choppers, which work with rotating blades and remove neutrons with unwanted energy, can allow neutrons with certain energy to pass through. In the design of a neutron velocity selector and the crucial role of these blades in its operation, simulation and experimental studies were performed to investigate the material and type of coating of the blades in relation to thermal neutron absorption. In this study, blades made of cadmium, aluminum, and carbon fiber with different coatings were exposed to thermal neutrons, and the neutron transmission was calculated using the MCNPX code. Based on the simulation results, blades with cadmium coatings and coatings of B4C, LiF, and H3BO3 with specific thicknesses were designed. The thermal neutron absorption of the constructed blades was measured in a thermal neutron flux from an Am-Be source using a BF3 detector. The results show that the cadmium blade without coating (1 mm thick), the aluminum blade (0.5 mm thick), and the carbon fiber blade (0.9 mm thick), both with B4C coatings, have the highest thermal neutron absorption values. The simulation and experimental results show that a B4C coating with a concentration of  is suitable for neutron velocity selector blades.