INMATEH - Agricultural Engineering

6

Authors: Păun A., Nedelcu A., Neagoe V.

Productions of fodder crops harvested by the combine vary depending on the harvesting period, climate and soil conditions, plant growing level. Within the combine working process, the chopping drum is the most important working part, that is why three constructive variants, frequently used in fodder combines manufacturing, have been studied. The paper present the results of experiments performed for the trailed combine (CTF), endowed with equipment for harvesting grass fodder(EI) and ensiling corn (EP) and with three constructive variants of chopping drum.

6

Authors: Moiceanu G., Voicu Gh., Paraschiv G., Poenaru I.C., Pirnă I.

In nature the elements of a biological cluster, as they are just after harvesting or the material particles of a ground material never randomly distribute completely, but only after various distribution laws known in mathematical statistics. These distribution laws or functions can be Gauss laws, Lorentz laws, Euler laws etc. They can be graphically represented through two different curves: the probability density curve (the distribution curve) and the cumulative distribution law. The distribution functions are characterized by many specific parameters: average, standard deviation, limits, asymmetry etc. Studying different phenomena, in can be seen that although these belong to a different science, their distribution in frequency is alike, respectively the histograms have the same shape. For example, 90% of the physical phenomena can be explained with the normal distribution law (Gauss – Laplace law). In this paper a statistical study of physical–biological characteristics of two Mischanthus crops harvested in two consecutive years is presented: plants distribution according to height, the plants individual mass, plants diameter at the lower internod and at the upper internode, etc. There were determined the statistical parameters for various distribution laws (normal law, lognormal law, gamma law) which can point out the physical characteristics remembered before. Also, the specific mass of plants stalks was determined, based on its two components, bark and core, and also the energy consumption during stalk grinding process.

6

Authors: Patamanska G., Chehlarova-Simeonova S.

In recent decades changes in climate of Bulgaria have been observed, a warming trend was established, coupled with decreasing rainfalls, especially during the warm half of the year. This causes reduction of the agricultural production and prevents development of intensive agriculture without irrigation. There is a need for changing the existing irrigation systems towards improving their operation and management in order to develop productive, sustainable against altered climate conditions agriculture, which uses resources efficiently. The present article aims to analyze and evaluate the existing problems facing the irrigation sector in Bulgaria and to identify the main reasons for developmental delay. Key measures to be adopted for changing and renovation of existing irrigation systems and their management in order to increase the level of application of irrigation and water use efficiency are outlined.

8

Authors: Nagy E.M., Cota C., Cioica N.

In our country, at present, about 90% of the rural population uses the solid biomass as a source of heat. In Romania, biomass represents an important source of energy not only in rural but also in urban areas. Under these circumstances it is important to know the potential of biomass, both theoretical and real, not only at national level, but also divided by region or even in certain clearly defined areas. This paper brings in a general method for evaluate the energy potential of solid biomass at national level. The proposed method is based on systemic analysis on the one hand, and on the other hand, is based on utilization of statistics available at national level, and it can be applied to determine the energy potential of biomass coming from only a certain vegetal or wooden category, or from a certain area clearly defined. Also, in the present work is performed the evaluation of the real energy potential stored in agricultural residues resulting from harvesting of 10 ha of wheat. This method of evaluation is useful in determining the real energy potential of solid biomass and allows farmers to choose correctly the category of biomass grown to be energetically capitalized.

10

Authors: Cârdei P., Sfîru R., Stefănoiu M.D., Bădescu M., Boruz S., Lazar S.

This article is the first among a series of three articles describing mathematical models of fodder harvesting combines energegetics, in order to optimize their working regimes. Starting from scientific literature of 1970-1980s, the classical models have been improved and adjusted, obtaining new models and results. The calibrating method of mathematical models is shown in order to determine the model constants which are not given by specialty literature. There are made references to manner of validating the results and possible applications in a wider domain of technique and science. The three articles are structured according to complexity of mathematical models elaborated and used for optimization. The first article deals with generalities and unidimensional model, namely that model considering a unique speed for working regime, idle speed and at turnings. The second contains models that consider the working speed and turning speed equal to idle speed, and the third one will describe the models containing the three speeds as independent variables.

8

Authors: Sfîru R., Meca A., Cârdei P., Muraru V., Mihailov N., Atanasov At.

The article presents an optimizing method of agricultural equipment selection by users, dealing with databases and different objective functions, all finally materializing in benefits of energetic nature.

8

Authors: Stefănoiu M.D., Cârdei P., Vlădut V., Boruz S., Lazar S., Fodor M.

The problem of the optimization of working regimes of agricultural aggregates remains one of current, even if their approach began with over a half of century ago or even earlier. The reasons for the problem remains in the study are several: difficulty of verifying experimentally the optimality of solutions, the existence of some solutions with certain errors in the specialty literature of reference, the complexity of mathematical models on which is solve the problems of optimality and which introduce new parameters, necessary for obtaining of some functions goal which would have optimal points in the strict sense of local extremum, parameters which however are not usual and are difficult to determine by measurements. This article starts from a known method from the literature of the '70, corrects the solution and modifies slightly the mathematical model in order to make its calibration on a specific case so that the final results–the coordinates of the optimal point - to be obtained numerically and compared with data from the literature.

8

Authors: Ciupercă R., Popa L., Lazăr G., Drăgan R., Aliyev Ch.

The paper presents a comparative study on mechanized process of planting vegetable seedlings, performed by two types of machines among the most common and used vegetable farm machines, respectively machine with a section equipped with rotative distributor with buckets and a second type- with section endowed with supply chain and planting flexible disks. After the analysis performed, the advantages and disadvantages of two machine types studied have been found out, in terms of technology of vegetable seedling planting.

8

Authors: Cârdei P., Kostadinov G.

The article continues to present some results related to those in [3], thoroughly studying the results of aggregates working optimization operating mode designed to soil works, their significance and interpretation.

10

Authors: Danciu A., Brătucu G., Vlădut V., Brkic M.

Because of machining precision by pairing and running in (lapping) of the conjugated parts (piston and cylinder), the manufacturers, in order to not reject several parts assembled have recourse to execution of several diameters for these parts so that to be respected the conditions of ovality, conicity and the clearance between the conjugated components (max. 0.5÷2μm). To highlight the size and shape of the injection pump elements (piston and cylinder) worn-out after the completion of an operating cycle on the engine, were taken randomly from a sample of 141 injection pump elements, studying the distribution of these dimensions. The study of sizes distribution or of the effective deviations from shape of pistons and cylinders (bushings) of the worn off injection pumps elements, had as scope the knowledge of dimensions range of these, in order to check the possibilities to re-establish the operational state of these by lepping and re-pairing, pursuing and the determination of the number of measuring pneumatic completes, required in the resettlement process of the operational state of these. The statistical and mathematical processing aimed to: - determination of average diameters on two directions and in each of the three plans of measurement (both for pistons and for the cylinders of elements); - the determination of pistons ovality and cylinders respectively in the three plans of measurement; - the determination of averages for the piston conicity (cmed)) and for cylinders (CMED); - the determination of averages of the clearances in the three measurement plans for the conjugated parts; - sorting in ascending order of the pistons and cylinders; - highlighting the possibilities to restore the operating status of injection pump elements.

6

Authors: Meca V.A., Cârdei P.

The researches whose results are presented in this article aim to theoretically optimize the agricultural machines designed to prepare the germinating bed. For ploughing machinery, an optimization method has been known since 1970-1980. The movement resistance force of ploughing machines was expressed in relation with the forward speed by a formula known since the middle of past century. By means of this formula, the method of optimizing the working regime of ploughing machines was achieved. For the machines designed to preparing the germinating bed, the formula giving the calculation of movement resistance does not depend explicitely on speed, and the constant expressing the soil action in contact with working parts is a global one- a resistance density per machine working width. This constant should be experimentally determined. Our researches have aimed to modify this formula of calculation of movement resistance similarly with that of plowing machines and solve the optimizing problem taking into account the method already used. The researches frame within a scientific unifying current in the field of agricultural mechanics, which purpose is to reduce the diversity of expression by other procedures and generalization. Renouncing to use special formulae lead to large opportunities in conceiving, designing and testing agricultural machines, the agricultural mechanics formulae taking its roots in modern science base.

6

Authors: Ovidiu M., Muntean L. S., Drocas I., Muntean M.

The main purpose of this study was to identify seed conditioning procedures for the species Melissa officinalis L., considering the difficulties encountered due to the small size and weight. Starting from this objective and using a sieving machine one has tried to develop a sieve separation techniques of seeds from flowers. In the experimental tests, as working material seeds of two months old were used, taking into account two factors: time of sieving (5, 10 and 15 minutes) and sieving amplitude (0.2, 1 and 2.2 mm). The results from experimental investigations have shown the possibilities to use sieve conditioning of Melissa officinalis L. species seed, but also noted the need to use further procedures for seed separation from impurities using currents of air. The main result consists of identifying the sieve time and the amplitude of the sieve.

8

Authors: Constantin N., Irimia D., Persu C., Cociu A.

Multifunctional aggregate for soil tillage in agricultural fields - MATINA is based on conservative agriculture system which consists in the main soil operation without furrow overturning, the vegetal wastes being superficially incorporated and at least 30% out of their amount being maintained at soil surface. This system assures competitive productions in terms of quality and quantity similar to those classically obtained, but with reduced costs and high profit, while improving soil features and preserving environment. The aggregate laboratory-field tests have been performed within private agricultural farms in Dolj and Teleorman county for tilling the soil in unplugged lands (in spring) and in wheat and barley stubble (in summer), during April-August 2011. MATINA performs at a single passing, the following agricultural operations: soil deep loosening with loosening parts, in order to facilitate plants roots easily to penetrate into the soil in search of water and nutritive elements; preparing the germinating bed with specific working parts; soil breaking and additional leveling by means of rollers with rods. During the field-laboratory tests, procedures elaborated by INMA-DI have been used, measuring and monitoring equipment (EMM) in terms of metrology verified, have been also used and appropriate working qualitative and energetic indexes have been obtained. Productions of crops set up in spring of 2011 in soil worked with MATINA have been similar to those obtained by classical system, with expenses by about 50% less.

8

Authors: Ivan Gh., Nedelcu M.

The article presents the part four of the study of pile displacement on the straw walker of conventional grain combine harvesters, in order to determine the structural and functional characteristics of the straw walker, to increase its working capacity. The material presented in the article represents the study of functions tsalt(k,α,δ,f) and S(k,α,δ,f,), duration and size of displacement of a pile jump on the shaking element at a complete rotation of it

8

Authors: Popa Gh., Constantinescu A., Dumitru I. , Vlădut V.

The paper presents the calculation of traction of a tractor equipped with additional hydrostatic transmission of mechanical transmission. The variation of the hydraulic parameters – the working liquid pressure, the hydraulic pump delivery – modify the parameters of the hydraulic motor – the rotation speed of the motor axle, the motor torque – and, also, the traction performances of the tractor. Also, wheeled traction performance are influenced by constructive and functional parameters of tractor tire, parameters influencing the interaction between the ground and wheels.