Investigation of Initial Wear Period of Differently Coated Carbide Cutting Tools

In this paper the results of experimental studies concerning the phenomenon of initial period of the wear of differently coated sintered carbide tools when dry orthogonal cutting of an AISI 321 austenitic stainless steel are presented. The motivation for this study results from the lack of technological guides concerning the optimal choice of coated cutting tools for machining of corrosion resistant austenitic stainless steels. A number of cutting tool inserts with the plane rake face made of a fine H10F sintered carbide substrate with specially deposited TiN, including TiCN, TiAlN, AlTiN and AlCrN single layers were used in wear tests. Both rake and flank faces of the cutting inserts were examined by optical and confocal microscopy after controlled tool wear. The possible wear mechanisms in terms of changes of the tool-chip contact were investigated

Analysis of mechanical characteristics of face milling process of Ti6AI4V alloy using experimental and simulation data

This paper presents experimental and 3D FEM simulation results obtained for the Johnson-Cook material constitutive model and variable cutting conditions. Face milling tests were carried out using a Ti6Al4V titanium alloy as the workpiece and coated carbide indexable inserts. CAD models of the cutting tool insert and the face milling head were generated and implemented into FEM package used. The machining conditions were selected based on real production data from aerospace sector. In particular, changes of power and specific cutting energy were analyzed in terms of the rotation angle of the milling head and the ratio of the uncut chip thickness against the cutting edge radius

Holter monitoring demonstrates that ventricular arrhythmias are common in cats with decompensated and compensated hypertrophic cardiomyopathy

Arrhythmias can complicate cardiac disease in cats and are a potential cause of sudden death. The aim of this study was to evaluate the presence and nature of cardiac arrhythmias, and the potential correlation between plasma serum troponin I (cTnI) concentrations and the presence or severity of arrhythmias in cats with decompensated (dHCM) and compensated hypertrophic cardiomyopathy (cHCM). Forty one client-owned cats were studied: 16 with cHCM, 15 with dHCM and 10 healthy control cats. Physical examination, echocardiography, cTnI and 24-h Holter recordings were obtained in all cats and thoracic radiographs in cats with dHCM. Cats in both HCM groups were followed for 1 year after their initial Holter examination.The median (range) number of ventricular premature complexes (VPCs) over 24 h was 867 (1–35,160) in cats with dHCM, 431 (0–18,919) in cats with cHCM and 2 (0–13) in healthy control cats. The median number of episodes of ventricular tachycardia (VTach) was 0 (0–1497) in dHCM and 0.5 (0–91) in cats with cHCM. The number of VPCs, VTach episodes and heart rate was not different between the HCM groups. Plasma serum troponin I was highest in the cats with dHCM, but there was no correlation between cTnI concentration and the number of arrhythmias. Thirteen of 31 cats with HCM died, but an association with the presence and complexity of ventricular arrhythmias was not observed. Compared to healthy cats, ventricular arrhythmias were common in cats with cHCM and dHCM, but neither presence nor complexity of arrhythmias could be linked to prognosis

Value Changes in Adolescents’ Anticipation of Possible Career Selves in Slovenia and Serbia

A study on adolescents’ visions of the future, regarding the important goals for themselves and plans for their accomplishment, was conducted on representative samples of high-school students in the last grades in Serbia (N = 1.973) and Slovenia (N = 882), in the autumn of 2015. The adolescents filled out a questionnaire on their visions of the future in different domains. We focused on their career as the central topic of their visions about future selves, which is assumed as conditional for fulfilment of the other identity domains and could be accomplished mainly due to individual efforts and flexible adaptation to environmental opportunities. These differ between the two countries, which experienced different post-socialist transitions into the market economy (and related value changes towards individualism) since early 1990s, from the previous common state, the Socialist Federal Republic Yugoslavia. As hypothesized, these different societal changes were reflected in the adolescents’ visions about their future career