INMATEH - Agricultural Engineering

6

Authors: Anghel St., Usenko M.

The paper presents theoretical research on modelling and simulation of U-650 M tractor power steering . Starting from developing of the model we realised its simulation following the evolution of main parameters in time. The results can be used to study the behaviour of power steering in operation

6

Authors: Filip Ilie

Nanoparticles have been widely used in polishing slurry such as chemical mechanical polishing (CMP) process. The movement of nanoparticles in polishing slurry and the interaction between nanoparticles and solid surface are very important to obtain an atomic smooth surface in CMP process. Nanoparticle’s behavior in the slurry with law viscosity has a great effect on the wafer surface in polishing process. Hydrodynamic pressure is periodically generated on the surface of asperity when nanoparticles are passing through the zone. Due to the periodical pressure, fatigue fracture occurs and begins from the top to the bottom of the asperity, then the material on the top is removed. Removal rate is calculated based of energy theory of balance fracture , and result shows a good agreement with experiment data. In this paper we present both experimental and theoretical studies on the movement of nanoparticles in polishing slurry and collision between nanoparticles, as well as between the nanoparticles and solid surfaces in time of process of CMP by exploring a model of microscopic friction based on the surface topography. Experimental results have proved that the nanoparticle size and slurry properties have great effects on the polishing results. The effects of the nanoparticle size and the slurry film thickness are, also discussed.

8

Authors: Dutu M.F., Maican E., Dutu I., David L., Rusănescu C.O.

This paper presents the two degrees of freedom of mathematical modelling of a tractor wheel. The tractor is a complex mechanical system that, while traveling, is subjected to vibrations that are transmitted from the running path to the driver. A modelling program was used in order to study the tractor movement on agricultural land. Useful charts were developed for: amplitude variation of the tractor’s mass center oscillation, with traveling speed; amplitude variation of the angle of rotation of the tractor around its center of mass; amplitude variation of the driven wheel with speed; driving wheel’s amplitude variation; amplitude variation of vertical force acting on driven wheel, with speed; amplitude variation of vertical force acting on driving wheel, with speed. There are also presented the study results for a tractor traveling on a country road. Interpretation of results is based on charts for amplitude variation of the tractor’s center of mass, amplitude variation of the angle of rotation of the tractor around its center of mass, amplitude variation of the driving and driven wheel when tractor is moving, amplitude variation of vertical force acting on driving and on driven wheel, with speed.

8

Authors: Constantin G.A., Voicu Gh., Stefan M.E., Paraschiv G.

In the paper it is presented the flow diagram of the wheat breakage phase in a milling plant with the capacity of 4.2 t/h, as well as the experimental results of the granulometric analysis of the grist from the plane sifter compartment of the Second Break. It is presented the particle size distribution of the grist that comes from the grinding rolls, but also the five grist fractions in which it is divided into plane sifter compartment of respective passage. Experimental data obtained for the particle size distributions of grist fractions were tested by computer regression analysis , with known distribution laws: Schuhman, Rosin-Rammler, Gauss and log-normal, determining the values for the equations coefficient and the correlation coefficient R2.

10

Authors: Moise V., Biris S.St., Kabas O., Ungureanu N., Vlădut V., Boureci Gh., Stroe I., Caba I.L.

To establish a machinery system and the optimal mechanization technologies for different types of agricultural farm and for various specific conditions it is necessary to use scientific methods of optimization. The success of a business, including agriculture, is determined by the amount of profit, which depends on the quality and quantity of the achieved product. To determine the minimum surfaces from which a certain power range of tractors becomes profitable, the income limit must be equal to the costs required to perform works in that area. In this paper is determined the optimal surfaces matrix for 20-65 HP tractors, used in family farms. For the determination of the minimum surfaces, incomes and necessary costs for the considered works must be taken into account. The optimal usage time of the tractors, the matrices of aggregates yields, as well as the matrix of equipment costs are also determined. Various methods of numerical optimization are used. After running numerical calculus and optimization programs, has been observed that, in case of family farms, the minimum surfaces from which a certain power range of tractors becomes profitable decreases if the work is performed by the farmer, with personal equipment. It has also been observed that the minimum surface required for the profit to be equal to zero at the limit, decreases with higher quality of the equipment.

10

Authors: Boja N., Boja F., Caba I., Gligoras D., Dărău P. A.

The present research displays the results obtained after the digging of holes for planting saplings in a previously unprepared soil, following the steps to carry them out according to some physical-mechanical properties of the soil. The research was carried out on a horizontal ground in the O.S. Iuliu Moldovan, in two arranged unities (parcels) 31 C and 32 A, in a previously unprepared ground, on two types of soil: gley-soil (the muddy subtype) and alluvial soil (the vertical-gleyed subtype), and in O.S. Radna, u.a. 74, on a brown typically luvic soil, using the Stihl BT 121 motto-borer with a 150 mm drill. The objectives of the research were to make a comparative determination, on different types of soil, of the qualitative parameters, among which the most important ones are: degree of loosening of the soil taken and left in the hole, resistance to penetration, resistance to shearing, timing of drilling holes, degree of scattering of the soil taken out from the hole, degree of evacuation of the soil from the hole, gas consumption for the drilling of the hole, using the Stihl BT 121 motto-borer in order to establish its technical efficiency. In order to observe the influence which the drilling of holes have on walls, we measured the resistance to penetration and resistance to shearing every 10 cm at a 30cm depth, the proper depth for planting small-sized saplings, on two opposite sides, so that we could get the most probable values of these physicalmechanical properties of the soil. After taking the measures in order to establish the compaction degree of the wall and of the bottom of the hole by the borer in that interval, it was judged that in conditions of normal humidity, if the borers have sharp knives and are well conceived and executed in technical terms speaking, there are no big values of the resistance to penetration which could affect the subsequent development of the saplings.