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This paper analyzes the problems related to the reconstruction of a semi-mounted berry harvester into a self-propelled one specified for exploitation on smaller orchards. The components of the self-propelled machine, their purpose and mutual functional connection are described in details, which retained the principle of unilateral picking of half the row of bush berries from its semi-mounted predecessor. Among the most important general design features, the following stand out in particular: the drive of the harvester working components, which is achieved by means of appropriate combinations of hydraulic and mechanical power transmissions, which allows it to be highly adaptable to different working conditions on the terrain, and the control device, which is designed to maintain the movement of the machine in the direction set by the driver, without decreasing the safety and passability requirements of the machine itself. In the technology of berry fruit production in the Republic of Serbia, the harvesting process is still the basic limiting factor. Manual picking participates as much as 75% in total production costs. The costs of mechanical harvesting are between 2.05 and 2.27 times lower in comparison to manual picking, depending on whether the machine is a towed or self-propelled. The paper also provides a comprehensive analysis of the energy parameters of work for both versions of the harvester. The results indicate that power losses on rolling and slipping are lower in the self-propelled version 10 and 40%, respectively, while in the semi-mounted version the power lost on the climb is 60-70% lower compared to the self-propelled version. As the harvesting process is still a limiting factor in berry fruit production, in addition to reducing costs by applying mechanized solutions, one of the goals of the work is the optimization of applied technical solutions for the same.

In agricultural production, sowing is one of the most important agro-technical operations that influence the quality of the product and yield. The crops sowing quality, including wheat, depends on properly prepared soil, that is, on the quality of soil cultivation. However, despite well-executed soil cultivation, satisfactory results cannot always be achieved if sowing is not done in an appropriate manner. The achieved depth of sowing affects the speed of sprouting, rooting, resistance of plants to low temperature and drought, intensity of budding, growth and development, and achieving the highest yield in certain conditions. In unfavorable agro-technical conditions, and especially in the conditions of dry farming, optimal conditions for high-quality sowing often cannot be ensured by applying the conventional method. Therefore, new cultivation and sowing systems are being applied in order to perform high-quality sowing in time. During the experiment, the influences of the tillage system and sowing method on the sowing depth and the depth of the formation of the tillering nodes were registered. The results of two-year study are given, where four methods of tillage were applied, namely conventional tillage at depths of up to 25 cm and three reduced tillage methods at different depths. Reduced cultivation with a discc harrrow was done at a depths between 8 and 12 cm, and reduced cultivation with rototiller was done at depths of 5-10 cm and 10-15 cm. During the tests, the sowing depth and the depths of the tillering nodes were determined by direct measuring of the knots positions of the analyzed plants. Furthermore, it was verified that depth of the knot has a significant effect on the resistance of wheat to low temperatures during winter and lack of moisture during summer droughts. Achieved results enable further optimization of applied cultivation and sowing systems.

Novi rekonstruisani kombajn ELEKTRONIK SP-09, je samohodna mašina koja je od svoga predhodnika ELEKTRONIK SP-07 zadržala princip jednostranog ubiranja polovine reda žbunastog jagodastog voća. Mašina je posebno prilagođena za branje remontantnih sorti maline bez potpore, mada se može uspešno koristiti i za druge vrste voća žbunaste forme. Razdeljivač usmerava jednu polovinu račvastog žbuna do jedinice za protresanje, gde vibrirajuće palice odvajaju bobice. Iz mase plodova, koji se transportuje kosom transportnom trakom na horizontalnu, struja vazduha iz ventilatora uklanja primese. Transportna traka može puniti male gajbice, a kapacitet prostora za odlaganje punih gajbica je oko 200 kg. Hidrostatički pogon pokreće SUS motor snage 50 kW. Parametri rada radnih delova se podešavaju da bi otpali samo zreli plodovi. Mogu se podešavati: - amplituda i frekvencija oscilovanja, - prečnik valjka i dužina palica, - prečnik palica, - radna brzina berača-kombajna. Među najvažnijim opštim konstruktivnim karakteristikama ističu se: - jednostavan modularni dizajn, koji omogućava: • uskladjivanje mašine sa specifičnim potrebama korisnika, • brzo i jednostavno prilagodjavanje za ubiranje različitih vrsta jagodastog voća. - pogon radnih komponenata kombajna ostvaruje se pomoću odgovarajućih kombinacija hidrauličnih i mehaničkih prenosnika snage, što mu omogućava veliku prilagodljivost različitim radnim uslovima na terenu (sl. 2 i 3). - posebna oscilujuća glava sa glatkim, plastičnim palicama na otresajućoj koloni; - pred-separator za uklanjanje nečistoće manjih dimezija; - dodatni separatorski transporter, koji olakšava uklanjanje oštećenih plodova; Pogon hidrauličkog sistema čine četiri jednosmerne zapreminske pumpe stalnog protoka: P1, P2, P3 i P4. Paralelno su spregnute, a pogon im omogućava zajedničko vratilo, koje snagu od dizel SUS motora kombajna (M) preuzima preko jednostepenog kaišnog prenosnika prenosnog odnosa i=1. Ovaj tip prenosnika, uz tiši rad, jednostavnu konstrukciju i

The article is focused on the behaviour of the basic properties of dairy cow's solid manure over the maturation period. The manure was exposed to mechanized aerobic processing by mechanically turning-over. Performed analysis comprehended measurements of mass participation percentages of organic components, mineral matters, H2O, N, P2O5 and K2O, as well as measurements of PH-values during the seven weeks of supervised test period of effective aerobic preparation of the composting material. Through maturation, large growth of averaged mass percentages of nitrogen, phosphorous-pentoxide and potassium-oxide, more than triple in comparison to the initial levels in a fresh solid, has been verified. Following a possible common approach in the scientific and technical practice, an analytical semi-empirical approach was used in describing the changes over the time of manure properties during composting, supported by prototype of the machine Kompomat 1. Combining the analytical theory of diffusion partial differential equations and application of numerical methods to non-linear fitting of the experimental output data, it was verified that all acquired manure parameters follow an identical general exponential law (R2all properties = 0,906 - 0,990; RMSEall properties = 0,010 - 2,544). Clear relationships between the values of basic parameters of solid manure under mechanized aerobic fermentation (y) and composting duration lap time (x) have been established.

This paper presents the tests results of three types of hay mowing machines (later in text: mowers), namely a self-propelled oscillatory mower-conditioner and two tractor-mounted mowers with oscillatory and rotary blades, used to mow alfalfa grown under dry land conditions in the region of central Serbia during three seasons in 2014, 2015 and 2016. Although characterized by older design, they are still commonly used at smaller and medium size farms in this region. Therefore, their optimal exploitation parameters are still of large importance for hay quality and production efficiency and sustainability. The exploitation parameters of all three mowers generally increased linearly with higher speeds, having high R2 values (over 0,8), with rare exceptions. The regression coefficients b clearly showed that the self-propelled mower-conditioner achieved maximum increase in production performance (b = 0,3606), compared with the oscillatory (b = 0,1158) and rotary mowers (b = 0,1414). Mower design had a significant (p ≤ 0,001) effect on cutting and chopping losses, production performance, and specific fuel consumption (p ≤ 0,05). The tests confirmed the superiority of the self-propelled mower over the two mowers aggregated with tractors.

One of the technical factors from agricultural nozzles and overall plant protection is droplet diameter, which exclusively depends on working pressure, ISO number and nozzle type. Therefore, this paper was aimed to describe mathematical model for droplet size distribution. Through field exploitation experiment, data was used from three ISO numbers of nozzles (hollow cone 80 015; 02 and 03), two air-assisted sprayers (axial and radial fan) and two permanent crops (vineyard and an apple orchard). Water sensitive papers were used for evaluation of droplet diameters, and digital image analysis with Image J software was used for data processing. Mathematical model through homogenous diffusion equation and simplified differential equation shows that droplet size distribution had exponential function of modelling. Theoretical mathematical model was confirmed in experimental results, where coefficient of determination of exponential regression model for 80 015 nozzles was 0.93 with 5.15 of RMSE. The same coefficient for 80 02 nozzles was 0.96 with 2.88 of RMSE and for 80 03 nozzle R2 was 0.93 with 3.25 of RMSE. In addition, it is proved that droplet diameter depends on operating pressure with very high negative correlation (80 03 nozzles: r = −0.98; 80 02 nozzles: r = −0.97; 80 015 nozzles: r = −0.95). This data will help future researchers in their papers to facilitate and describe similar models for plat protection processes, and all agricultural producers to determine optimal operating pressure which is immensely important in economic, biologic, technical and ecologic aspect.

This paper analyses the capacity of a bulk cargo unloading river terminal, i.e. the existing terminal configuration with two unloading devices (operation without a help strategy and under a complete help strategy between unloading devices) and the predicted future terminal configuration with three unloading devices operating under a partial help strategy. The optimization procedure to determine unloading terminal optimal utilization, for each terminal configuration and operation strategy (existing and future situation) is also shown, due to the fact that ports (terminals) operation under an optimal capacity provides prompt accommodation of vessels with the minimum port waiting time and maximum use of berth facilities. For the purpose of a comprehensive analysis, three different river terminal simulation models have been developed due to the number of unloading devices and their operation strategy. Some of the obtained results have been applied and verified on the existing system.

When filtering products with a high level of non-soluble solids and containing filtration-inhibiting substances, a variety of different filter aids can be used. Among others, kieselguhr and perlite are possible materials for this purpose. The selection of the granulation that should be applied depends on the filtered liquid medium and the desired retention level. While perlite is most commonly used for rough filtration, kieselguhr is also suitable for more subtile filtration. In the paper, particle size distributions of three kieselguhr granulations and a perlite granulation are analysed. Particle sizes are measured by the morphometric method commonly used in the microbiology. Basic statistic parameters are calculated for all considered samples and compared. The applicability of hyperbolic and log-hyperbolic functions, in describing the particles size distributions of these granulations is verified. Depending on the imposed filtration requirements, this approach enables simple modelling and composition of a wide variety of different granulations characterised by appropriate particle size distributions from a few available granulations.