Advantage of use of activated flux-cored wire instead of solid wire with the mag welding process from the mechanical properties aspect

The objective of this paper is the analysis and evaluation of the quality of the new flux-cored wire designed for the MAG welding process that was developed and produced using special laboratory equipment. Experimental welding was performed with the new activated flux-cored wire and classic solid wire with changing of welding parameters and shielding gas composition (100 % CO2 and gas mixtures of Ar + CO2 + O2)

Modeliranje hrapavosti obrađene površine i optimiranje parametara obrade pri čeonom glodanju

The influence of cutting parameters on surface roughness in face milling has been examined. Cutting speed, feed rate and depth of cut have been taken into consideration as the influential factors. A series of experiments have been carried out in accordance with a design of experiment (DOE). In order to obtain mathematical models that are able to predict surface roughness two different modeling approaches, namely regression analysis and neural networks, have been applied to experimentally determined data. Obtained results have been compared and neural network model gives better explanation of the observed physical system. Optimal cutting parameters have been found using simplex optimization algorithm.U ovom radu istražen je utjecaj parametara obrade (brzina rezanja, posmak i dubina rezanja) na hrapavost obrađene površine pri čeonom glodanju. Obavljen je niz pokusa u skladu sa planom eksperimenta. U cilju dobivanja matematičkog modela kojim se može predvidjeti hrapavost obrađene površine, eksperimentalni podaci obrađeni su metodologijom regresijske analize i neuronskih mreža. Uspoređeni su dobiveni rezultati i neuronska mreža daje bolji opis promatranog fizikalnog sustava. Primjenom simplex algoritma za optimiranje dobivene su optimalne vrijednosti ispitivanih parametara

Modeliranje hrapavosti obrađene površine i optimiranje parametara obrade pri čeonom glodanju

The influence of cutting parameters on surface roughness in face milling has been examined. Cutting speed, feed rate and depth of cut have been taken into consideration as the influential factors. A series of experiments have been carried out in accordance with a design of experiment (DOE). In order to obtain mathematical models that are able to predict surface roughness two different modeling approaches, namely regression analysis and neural networks, have been applied to experimentally determined data. Obtained results have been compared and neural network model gives better explanation of the observed physical system. Optimal cutting parameters have been found using simplex optimization algorithm.U ovom radu istražen je utjecaj parametara obrade (brzina rezanja, posmak i dubina rezanja) na hrapavost obrađene površine pri čeonom glodanju. Obavljen je niz pokusa u skladu sa planom eksperimenta. U cilju dobivanja matematičkog modela kojim se može predvidjeti hrapavost obrađene površine, eksperimentalni podaci obrađeni su metodologijom regresijske analize i neuronskih mreža. Uspoređeni su dobiveni rezultati i neuronska mreža daje bolji opis promatranog fizikalnog sustava. Primjenom simplex algoritma za optimiranje dobivene su optimalne vrijednosti ispitivanih parametara

Influence of the impurities on the depth of penetration with carbon steel weldings

In this paper the results of the research about the influence of the impurities on the depth of penetration with carbon steels weldings of different chemical composition are presented. These data suggest that presence of those impurities, such as sulphure and oxygen, in the steel, increases the depth of penetration to 1,3 - 1,5 times compared to welding refined steels. Applying activating fluxes for welding high tensile steels, provides an increase in the depth of penetration of 2 - 3 times

Pebble dynamics and accretion onto rocky planets. II. Radiative models

We investigate the effects of radiative energy transfer on a series of nested-grid, high-resolution hydrodynamic simulations of gas and particle dynamics in the vicinity of an Earth-mass planetary embryo. We include heating due to the accretion of solids and the subsequent convective motions. Using a constant embryo surface temperature, we show that radiative energy transport results in a tendency to reduce the entropy in the primordial atmosphere, but this tendency is alleviated by an increase in the strength of convective energy transport, triggered by a correspondingly increased super-adiabatic temperature gradient. As a consequence, the amplitude of the convective motions increase by roughly an order of magnitude in the vicinity of the embryo. In the cases investigated here, where the optical depth towards the disk surface is larger than unity, the reduction of the temperature in the outer parts of the Hill sphere relative to cases without radiative energy transport is only $\sim$100K, while the mass density increase is on the order of a factor of two in the inner parts of the Hill sphere. Our results demonstrate that, unless unrealistically low dust opacities are assumed, radiative cooling in the context of primordial rocky planet atmospheres can only become important after the disk surface density has dropped significantly below minimum-mass-solar-nebula values.Comment: 5 pages, 4 figures, 2 appendices; MNRAS Letters, accepte

On entropy of probability integral transformed time series

Abstract The goal of this paper is to investigate the changes of entropy estimates when the amplitude distribution of the time series is equalized using the probability integral transformation. The data we analyzed were with known properties—pseudo-random signals with known distributions, mutually coupled using statistical or deterministic methods that include generators of statistically dependent distributions, linear and non-linear transforms, and deterministic chaos. The signal pairs were coupled using a correlation coefficient ranging from zero to one. The dependence of the signal samples is achieved by moving average filter and non-linear equations. The applied coupling methods are checked using statistical tests for correlation. The changes in signal regularity are checked by a multifractal spectrum. The probability integral transformation is then applied to cardiovascular time series—systolic blood pressure and pulse interval—acquired from the laboratory animals and represented the results of entropy estimations. We derived an expression for the reference value of entropy in the probability integral transformed signals. We also experimentally evaluated the reliability of entropy estimates concerning the matching probabilities

Primjena plana pokusa u optimizaciji procesa glodanja

This paper examines the influence of cutting parameters on surface roughness of steel workpiece. The experiments have been carried out in accordance with a design of experiments (DOE). Equation for the surface roughness, as a function of cutting parameters, has been obtained by means of regression analysis. To obtain the minimal value of surface roughness, the equation optimizing was performed by using partial derivations and solving system of equations. The Taguchi method, with orthogonal arrays and signal to noise ratio, has been used to analyze impact of various cutting parameters on surface roughness and to find optimal levels of the cutting parameters. The comparison of results obtained by means of the response surface method and the Taguchi method was performed.U radu je istraživana kvaliteta obrađene površine čeličnog obratka pri različitim parametrima obrade. Pokusi su izvedeni sukladno odabranom planu pokusa. Regresijskom analizom dobivena je jednadžba hrapavosti obrađene površine u ovisnosti o parametrima obrade. U cilju dobivanja minimalne hrapavosti obrađene površine obavljeno je optimiranje jednadžbe parcijalnim deriviranjem i rješavanjem sustava jednadžbi. Taguchijeva metoda s ortogonalnim nizovima i omjerom signala i šuma korištena je za analizu utjecaja parametara obrade na hrapavost površine te pronalaženje optimalne razine parametara. Na kraju su uspoređeni rezultati dobiveni metodom odzivne površine i Taguchijeve metode