TECHNICAL AND ECONOMIC PARAMETERS FOR SELECTION OF THE OPTIMAL VARIANT OF THE REGIONAL IRRIGATION SUBSYSTEM

A model of the water management system is developed by connecting the technical and economic parameters that best represent the regional irrigation subsystems. The following technical parameters were analyzed: the location of water intake, configuration, and dimensions of the primary canal network, pipelines, and the number and location of pumping stations. Economic parameters depend on the technical ones and they are necessary investments for construction (€), unit investments (€/ha), investments for replacement of equipment during the period of exploitation (€), annual irrigation costs, and fixed irrigation costs (€/ha, €/m3), energy consumption and cost (kW, yearly h, yearly €), economic price of irrigation (€/ha, €/m3), break-even point analysis. The model was tested on the future regional subsystem "Telečka" with an area of about 25,145.00 ha, which will be part of the regional system "Severna Bačka" (AP Vojvodina, Northern Serbia). Based on the specified parameters, 6 potential variants for construction have been proposed. By ranking the stated quantitative parameters, the best effects are achieved in the 4.1 variant of the technical solution with the following values: total investments for the construction of 42.05 million €, unit investments of 1,670.00 €/ha, investments for equipment replacement of 4.20 million € every 10 years, costs of irrigation on the water intake 130.00 €/ha, fixed costs of irrigation 86.00 €/ha, economic price of irrigation 203.00 €/ha (for d.r. 6%). For the calculation of these parameters, data from the technical part of the plan was used, in which a large number of experts from different professions were involved. An improved planning methodology (using a simulation model) as well as the obtained technical and economic data can be used for comparison with other regional subsystems that are in similar conditions (e.g. climatic, soil, available water resources)

Analysis of Power Losses in Constrained Cycloid Drive

The aim of this paper is to present a theoretical model for efficiency evaluation of a simple cycloid drive train with one degree of freedom (DOF) or constrained cycloid drive. In order to evaluate the efficiency, it is necessary to find the losses generated in the simple cycloid drive, where only losses depending on the load were considered. Expressions for determining speed ratios, efficiency, velocities and forces acting inside the cycloid drive are presented. These expressions are implemented in the theoretical model, where the places where the losses occur are defined. A computer program was created to facilitate analysis and obtain loss values based on different input data. Only load-dependent losses were considered in the theoretical model and computer program. In order to verify the theoretical model, experimental measurements were performed. A physical model of the simple cycloid drive train was created and analyzed on the test bench. The results for "S1" operating mode, i.e. when shaft 2 is stopped, show a mean value of the efficiency of 63.49%, for experimental measurements, while the mean value for theoretical analysis is 65.25%. For the operating mode "S2", i.e. with shaft 1 stopped, the mean value of the experimental measurements of the efficiency is 60.9%, while the theoretical mean value is 62.82%

The irrigation influence on agricultural intensification in Serbia

The factors that influence on the intensification of agriculture on our estates (internal and external) are analyzed. Depending on the level of development and measures of agricultural policy, intensification process can be encouraged on many ways. In our case, the influence of constructing regional hydro system to increase the intensity (of production and economic effects) was investigated. Depending on the size of the hydro system, the volume of invested funds, as well as suggestions about possible restruction of the production, doubling of the economic and production effects can be achieved, on the condition that production management is in function of achieving our objectives. Realistically, in this case, the regional hydro system should be holders of intensification. They initiate the development of manufacturing industry and provide more quality goods for processing and market. Besides positive effects (direct and indirect) impact of irrigation on intensification, during long-term use on the same land, some negative effects were noticed (soil salinization, deterioration of water quality, irrigation erosion)

VALUATION OF REGIONAL HYDROSYSTEM CONSTRUCTION INFLUENCE ON RURAL DEVELOPMENT

Global effects of construction of regional hydrosystem "Srem" and its influence on regional development was analyzed using SWOT analysis. There are many advantages in favor of constructing this system: large area, over 200.000 ha, possibility of phase building, wide product range, new labor employment etc. Also, great contribution is in improving environmental conditions, building new facilities for food industry, hiring new labor, increasing products for export etc. The main weaknesses of this venture are great investment funds for building, unfavorable fnancing conditions, uneven soil quality and poor age structure of active population. Most of the analyzed criteria can be classifed and used later in selecting optimal system variant and sequence of construction. According to the data from the General project, it is necessary to provide over 700 million USD for construction, which is a substantial amount for Serbia and Voivodina, since building other regional hydrosystems are in plan

PREDICTION OF OIL FILM THICKNESS IN TROCHOIDAL PUMP

A model for predicting the oil film thickness between the contact surfaces of the gerotor pump teeth is given in this paper. Gerotor pumps are rotary pumps with inner trochoidal gearing. The working process of the pump is followed by mechanical losses due to friction that occurs between the coupled surfaces. In order to reduce these losses and avoid wearing of the teeth’s active surfaces, it is necessary to provide a minimum thickness of the oil film between the contact surfaces. The minimum thickness of the oil film depends on a large number of different factors, but in this paper for its determination, the Hamrock and Dowson empirical equation is used. Previously, the mathematical model that follows the change of relative velocities in contact, sliding velocity, rolling velocity and contact force at the contact points of the coupled teeth profiles is developed. The influence of different parameters on the lubrication regime has been analyzed, and it has been shown that the trohydraulic pump operates most with the limit EHD lubrication regime. The most unfavorable period occurs when the resulting rolling velocity decreases significantly, and this period dominates during coupling. The results of this research provide guidelines for the design of the tooth profile’s shape and the choice of operating parameters of the pump with high reliability.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Smjernice za liječenje benignih bolesti anorektalne regije

Benigne bolesti anorektalne regije, u koje ubrajamo analne apscese, analne fistule, analne fisure i hemoroidalnu bolest, česta su stanja koja susreću liječnici obiteljske medicine kao i bolnički specijalisti. Unatoč rasprostranjenosti patologije, još uvijek ne postoje jasne smjernice za adekvatno liječenje navedenih stanja, koje se još uvijek često svodi na preporuke koje nemaju uporište u medicini temeljenoj na dokazima. Zbog toga je ekspertna skupina, u kojoj su sudjelovali članovi Hrvatskog društva za digestivnu kirurgiju kojima je uže područje interesa koloproktologija, odlučili sastaviti ove smjernice s namjerom da se standardizira liječenje benignih bolesti anorektalne regije, kako na primarnoj tako i na tercijarnoj razini