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Temperature distribution in the metallic plate influenced by high-frequency electromagnetic wave depends on thermal and electrical properties of the plate material. The goal of the paper is to present the significance of the temperature dependence of the electrical resistivity and its influence on the plate heating. A mathematical model of the problem was established and an analytical closed-form solution to the problem was presented. The active power of the electromagnetic wave was calculated by Poynting vector. Temperature field was obtained by integral-transform technique. Numerical examples were presented for three different materials (copper, aluminum, and steel). Calculated results show the large influence of temperature dependent electrical resistance on heating of the metallic plate.

In a modern business environment with very big data flows, employee focus is crucial for success. This problem developed a need for new technological advancements such as Robotic Process Automation (RPA). As the RPA technology is relatively young, there is still an insufficient amount of research about which project management techniques are the best for it. This paper aims to recognize the key principles of risk management which can be applied to the automation of business processes through the use of RPA technology and to emphasize the significance of risk management for conducting successful RPA projects.

A theoretical film rupture model was used for computational procedure to predict the crack growth rate within the Stress Corrosion Cracking (SCC) conditions. Chemical, electrochemical and mechanical aspects of the SCC were analyzed and set into the computer program to calculate crack growth rate. Extended Finite Element Model (XFEM) was applied to calculate Stress Intensity Factor (SIF) in two loading modes - tensile test specimen and compact tension (CT) specimen. Elastic-plastic fracture mechanics (EPFM) was used for CT specimen. The computational model was verified with experimental results published in literature. Results have shown good agreement in two cases analysed here, stainless and common structural steel, indicating great potential of the XFEM to simulate the crack growth rate within the SCC conditions.

Pronalazak se odnosi na ispitivanje ramova i pokretnih spojeva prozora i vrata od aluminijuma i PVC-a, koji se koriste u stolariji, u uredajima za ispitivanje materijala na zatezanje, pritisak i savijanje-kidalicama.

In this research the 3-D transient non-linear thermal analysis of the hard-facing process was performed by using the experimental testing and finite element method. Testing was done at three different carbon steels and the obtained results were compared to one obtained by empirical formulas and welding recommendations. Experimental testing was done on hard faced specimens (plates) with different thickness. Temperatures and temperature cycles was measured by using thermocouples in order to determine maximal temperature and cooling time between 800 degrees C and 500 degrees C. After experimental testing the finite element method analysis was done. The simulations were executed on the open source platform Salome using the open source finite element solver Code Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental and mathematical results.

Sub-lethal doses of herbicides can promote plant growth and have a positive effect on an organism this is called hormesis. The purpose of this study was to test the effects of sub-lethal doses of glyphosate on soybean (Glycine max(L.) Merr.) (1.8, 3.6, 7.2, 36, 180, and 720 g ha(-1)) and Amaranthus retroflexus L. (7.2, 36, 180, 720, 1440, and 2880 g ha(-1)). Different biological parameters, such as phytotoxicity, fresh weight, root length, content of photosynthetic pigments, and shikimate concentration, were measured. Glyphosate in doses of 1440 and 2880 g ha(-1) destroyed A. retroflexus plants. A fresh weight of A. retroflexus at a dose of 36 g ha(-1) was reduced by 76.31%, while for the soybean it was reduced by 19.26%. At the highest dose, the shikimate concentration was 145% in the soybean, while in A. retroflexus, the concentration increased by 58.80% compared to the control plants. All doses of glyphosate were statistically significantly different in terms of chlorophyll a content, while higher doses in A. retroflexus caused chlorophyll b to decrease. The change in the production of carotenoids was not statistically significant. The results showed that sub-lethal amounts of glyphosate did not lead to stimulation of measured parameters of soybean.

Weed control in apple tree (Malus domestica [Suckow] Borkh.) orchards continues to be a major problem. Weeds compete with fruit trees, which is manifested in production quality and quantity. The aim of this study was to determine the weed flora of apple orchards with different floor management practices and to investigate the efficacy of the diquat, oxyfluorfen, glyphosate, and fluazifop-P-butyl herbicides. Experiments were conducted during 2015 and 2016 in orchards under intensive (Ruski Krstur) and extensive (Sombor) floor management. Annual, perennial broad-leaf, and grass weeds were identified. Dominant weed species in both apple orchards were Poa annua, Hordeum murinum, Conyza canadensis, Portulaca oleracea, Cynodon dactylon, Sorghum halepense, Carduus acanthoides, Amaranthus retroflexus, Cirsium arvense, Chenopodium album, and Solanum nigrum. After the first and second assessments, the best results occurred with glyphosate in both orchards and total efficacy ranged from 88.42% to 98.32% in the orchard under intensive floor management and 90.32% to 95.55% in the orchard under extensive floor management. Diquat and oxyfluorfen have shown good results, but their efficacy was lower than for glyphosate. Fluazifop-P-butyl, as a selective herbicide, showed low efficacy at both sites; it had high efficacy on grass weeds, but no effects on broad-leaf weeds.

Various factors of thermo-chemical erosion process in gun steel were analysed. The factors are mainly related to the thermal load of gun barrel inside surface, characteristics of barrel surface and chemical interactions between propellant combustion products and barrel surface. The experimental simulation of conditions in gun barrel was carried out by vented vessel firings in the device based on modification of 37 mm M39 gun. The nozzle mass loss during firing was the measure of gun steel erosion. The main thermal factor of erosion is maximum nozzle inner surface temperature. This temperature was determined experimentally by micro thermocouples measurements at specified distance away from the inner surface and by numerical analysis of the inverse heat conduction problem. Modelling of two-phase flow of propellant combustion products and unburned propellant grains in the vented vessel and heat transfer to the nozzle were conducted using developed 1-D interior ballistic code and CFD simulation in FLUENT. Influence of different propellants, TiO2/wax wear reducing liner and tungsten-disulfide nanoparticles layer on nozzle erosion was analysed. Good agreement between experimental and computational results was achieved.

This paper resulted from the research of the overpressure of the shock wave of the powder gases, which occurs during firing of the mortar. Work encompasses modeling and computation of the overpressure field. Increasing overpressure around the mortar is analyzed in the case of using the largest powder charges. In order to reduce the overpressure a corresponding technical solution has been proposed. The solution in the form of divergent nozzle has been proposed and it is placed at the barrel muzzle. The paper also analyzes the impact of this solution to reduce the overpressure intensity at the crew position. Computation results of the overpressure of the powder gases, which were obtained by the realization of numerical calculation, based on the application of the finite volume method, were confirmed by the experimental results, achieved in the firing experiments.

Reformer is an integral component of the polymeric electrolyte membrane (PEM) fuel cell and it is used for experimental combustion testing. By analyzing the geometry of the experimental reformer, it consists of three plates, two pins for leading and a single screw for sealing. In terms of technological analysis for manufacturing of the experimental reformer emphasis was thrown on the intermediate plate which is necessary to carry out Wire EDM machining. Before the machining based on CAD models it was performed tool part generation in order to perform machining simulation. In order to minimize manufacturing costs by techno-economic analysis it was varying the wire thickness, and therefore cutting parameters. Besides the variation of the cutting parameters it was varied and the intermediate plate thickness. It was made a three sets of experimental reformer, wherein the electrical discharge machining (EDM) was performed on two machines (Mitsubishi FA-10S Wire EDM and "Ewis" EV.00.000M4) with two different wire thickness. After machining is was carried out the welding procedure, and after that re-machining in order of remove the excess material which is applied by welding process.

The paper deals with the heat input and maximum temperature that develops in friction stir welding with different welding parameters. The finite element method has been used for numerical analysis of temperature distribution in a friction stir welded Al alloy. Results of temperature distribution in the friction stir welded T-joint and butt joint are presented.

The main tasks of this research is to propose several changes in the packed bed micro methanol steam reformer geometry in order to ensure its performance. The reformer is an integral part of the existing indirect internal reforming high temperature PEMFC and most of its geometry is already defined. The space for remodeling is very limited.

Assessment of airfoil aerodynamic characteristics is essential part of any optimal airfoil design procedure. This paper illustrates rapid and efficient method for determination of aerodynamic characteristics of an airfoil, which is based on viscous-inviscid interaction. Inviscid flow is solved by conformal mapping, while viscous effects are determined by solving integral boundary layer equations. Displacement thickness is iteratively added to the airfoil contour by alternating inviscid and viscous solutions. With this approach efficient method is developed for airfoil design by shape perturbations. The procedure is implemented in computer code, and calculation results are compared with results of XFOIL calculations and with experiment. Eppler E387 low Reynolds number airfoil and soft stall S8036 airfoil are used for verification of developed procedure for Reynolds numbers 200000, 350000, and 500000. Calculated drag polars are presented in this paper and good agreement with experiment is achieved as long as small separation is maintained. Calculated positions of laminar separation, reattachment, and turbulent separation closely follow experimental measurement. The calculations are performed in relatively short time, which makes this approach suitable for low Reynolds number airfoil design.