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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Sven Düzel, Robert Eberlein, Hans-Jörg Dennig; Fatigue life analysis of POM gears with transient material modeling. AIP Conf. Proc. 8 May 2024; 3158 (1): 110015. https://doi.org/10.1063/5.0204543 and may be found at https://doi.org/10.1063/5.0204543., The today’s standard calculation methods for investigating the load carrying capacity of polymer gears (such as VDI 2736) are based on the same assumptions as for steel gears. Due to strongly varying material properties of polymers regarding stiffness level, nonlinearity and rate dependency, the predicted lifetimes of polymer gears are inaccurate. In the current study a rate dependent nonlinear viscoplastic finite element (FE) modelling of polyoxymethylene (POM) allows quantifying the material influences not considered by standard assumptions for metal parts. By deploying such a nonlinear material model for POM, a POMsteel gear pairing is investigated and additionally validated on a gear test rig. Different rotational speeds but constant brake torque are investigated to analyse the influence of inertia under the dynamic conditions as well as the rate depended material properties to the fatigue lifetime. An accelerated approach for a repeated transient FE modelling of the gear meshing process makes it possible to investigate critical stress and strain states over consecutive cycles, specifically focusing on tooth root breaking. It turns out that a cyclic increase of (plastic) strains occurs in the polymer gear teeth roots. Through an extrapolation of the local maximum principal strain, the strain state of the failure causing cycles can be analysed and forms the basis for a fatigue life analysis of POM gears. In combination with a strain based failure criterion the admissible number of cycles of POM gears for various rotational speeds is predicted and validated against experimental results obtained from the gear test rig.

The Mini Labyrinth experiment is a simple neutron and gamma shielding experiment developed at STU, inspired by the ALARM-CF-AIR-LAB-001 ICSBEP benchmark experiment, originally constructed in the former Soviet Union in 1982. Compared to the original Labyrinth, which was made from concrete blocks and had dimension of several meters, the STU Mini Labyrinth is approximately ten times smaller and consists of NEUTRONSTOP shielding blocks. The purpose of this experiment is to validate the computer codes of STU and partners involved in the APVV-DS international project “Experimental and simulation shielding studies of materials used in radiation protection”. This paper gives a brief overview of the experimental workplace and brings the first experimental results and their comparison with computer simulation. The very first experiment performed in the Mini Labyrinth experimental workplace was focused on the measurement of neutron and gamma count rate inside the Mini Labyrinth using the Thermo Scientific RadEye dose meter. The experimental setup also consisted of a PuBe radioisotope neutron source and light water moderator placed in a plastic tank between the neutron source and the detector. The simulation part was carried out using the state-of-the-art MCNP6 and SCALE6 MONACO stochastic calculation tools taking into account the detailed geometry of the labyrinth and a combined neutron- gamma source of particles. The comparisons were performed between codes, based on dose rate in the unique detection positions and using a 3D map of neutron and photon fluxes, using the so called meshtallies. The comparison between the simulated and measured data was performed based on the measured neutron count rate

This paper presents the Metrological Laboratory for Thermophysical Quantities (MLTV) and its actual measurement possibilities. The MLTV is located in the Department of Thermal Engineering and Energy of the Institute of Nuclear Sciences VINCA in Serbia. It was founded in 1963, accredited by the National Accreditation Body in 2007 and became the national designated laboratory for thermophysical quantities and received the status of a EURAMET Associate Member in 2015. Today, the laboratory develops, maintains and disseminates traceability of different national standards, such as those for thermal conductivity of insulations and poorly conductive solid materials from 250 K to 350 K, thermal diffusivity of a large variety of solid materials from 200 K to 1450 K and specific heat and specific electrical resistivity from 250 K to 2400 K of electroconductive solid materials. Total hemispherical and spectral normal emissivity from 1200 K to 2400 K of electroconductive solid materials are also measured in the MLTV. The methods and experimental setups for the realization and measurement of all of these standards and quantities are described with corresponding examples.

The measurement of the Higgs production cross-section times the branching ratios for its decays into mu(+)mu(-) and ZZ* pairs at a 1.4 TeV CLIC collider is investigated in this paper. The Standard Model Higgs boson with a mass of 126 GeV is dominantly produced via WW fusion in e(+)e(-) collisions at 1.4 TeV centre-of-mass energy. Analyses of both decay channels are based on a full simulation of the CLIC_ ILD detector. All relevant physics and beam-induced background processes are taken into account. An integrated luminosity of 1.5 ab(-1) and unpolarised beams are assumed. For the H - GT ZZ* decay, the purely hadronic final state (ZZ* - GT q (q) over barq (q) over bar) is considered as well as ZZ* decays into two jets and two leptons (ZZ* - GT qql(+)l(-)). It is shown that the branching ratio for the Higgs decay into a muon pair times the Higgs production cross-section can be measured with 38% statistical uncertainty. It is also shown that the statistical uncertainty of the Higgs branching ratio for decay into a Z boson pair times the Higgs production crosssection can be measured with a precision of 18.3% and 5.6% for the hadronic and semi-leptonic ZZ* decays, respectively.

This paper presents the Metrological Laboratory for Thermophysical Quantities (MLTV) and its actual measurement possibilities. The MLTV is located in the Department of Thermal Engineering and Energy of the Institute of Nuclear Sciences VINCA in Serbia. It was founded in 1963, accredited by the National Accreditation Body in 2007 and became the national designated laboratory for thermophysical quantities and received the status of a EURAMET Associate Member in 2015. Today, the laboratory develops, maintains and disseminates traceability of different national standards, such as those for thermal conductivity of insulations and poorly conductive solid materials from 250 K to 350 K, thermal diffusivity of a large variety of solid materials from 200 K to 1450 K and specific heat and specific electrical resistivity from 250 K to 2400 K of electroconductive solid materials. Total hemispherical and spectral normal emissivity from 1200 K to 2400 K of electroconductive solid materials are also measured in the MLTV. The methods and experimental setups for the realization and measurement of all of these standards and quantities are described with corresponding examples.

The measurement of the Higgs production cross-section times the branching ratios for its decays into mu(+)mu(-) and ZZ* pairs at a 1.4 TeV CLIC collider is investigated in this paper. The Standard Model Higgs boson with a mass of 126 GeV is dominantly produced via WW fusion in e(+)e(-) collisions at 1.4 TeV centre-of-mass energy. Analyses of both decay channels are based on a full simulation of the CLIC_ ILD detector. All relevant physics and beam-induced background processes are taken into account. An integrated luminosity of 1.5 ab(-1) and unpolarised beams are assumed. For the H - GT ZZ* decay, the purely hadronic final state (ZZ* - GT q (q) over barq (q) over bar) is considered as well as ZZ* decays into two jets and two leptons (ZZ* - GT qql(+)l(-)). It is shown that the branching ratio for the Higgs decay into a muon pair times the Higgs production cross-section can be measured with 38% statistical uncertainty. It is also shown that the statistical uncertainty of the Higgs branching ratio for decay into a Z boson pair times the Higgs production crosssection can be measured with a precision of 18.3% and 5.6% for the hadronic and semi-leptonic ZZ* decays, respectively.

In this paper some initial results concerning the evolution of flame propagation in 4-valve engines with tilted valves were presented. Results were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry with moving boundaries. During induction fluid flow pattern was characterized with organized tumble motion followed by small but clearly legible deterioration in the vicinity of BDC. During compression the fluid flow pattern is entirely three-dimensional and fully controlled by vortex motion located in the central part of the chamber. The effect of turbulence model variation on flame propagation was tackled as well. Namely, some results obtained with eddy-viscosity model i.e. standard k-epsilon model were compared with results obtained with k-xi-f model of turbulence in domain of 4-valve engine in-cylinder flow. Some interesting results emerged rendering impetus for further quest in the near future. In the case of combustion all differences ensuing from turbulence model variation, encountered in the case of non-reactive flow were annihilated entirely. Namely the interplay between fluid flow pattern and flame propagation is invariant as regards both turbulence models applied.

In this paper some initial results concerning the evolution of flame propagation in 4-valve engines with tilted valves were presented. Results were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry with moving boundaries. During induction fluid flow pattern was characterized with organized tumble motion followed by small but clearly legible deterioration in the vicinity of BDC. During compression the fluid flow pattern is entirely three-dimensional and fully controlled by vortex motion located in the central part of the chamber. The effect of turbulence model variation on flame propagation was tackled as well. Namely, some results obtained with eddy-viscosity model i.e. standard k-epsilon model were compared with results obtained with k-xi-f model of turbulence in domain of 4-valve engine in-cylinder flow. Some interesting results emerged rendering impetus for further quest in the near future. In the case of combustion all differences ensuing from turbulence model variation, encountered in the case of non-reactive flow were annihilated entirely. Namely the interplay between fluid flow pattern and flame propagation is invariant as regards both turbulence models applied.

Lichen and Moss are widely used to assess the atmospheric pollution by heavy metals and radionuclides. In this paper, we report results of uranium and its isotope ratios using mass spectrometric measurements (followed by chemical separation procedure) for mosses, lichens and soil samples from a depleted uranium (DU) target site in western Balkan region. Samples were collected in 2003 from Han Pijesak (Republika Srpska in Bosnia and Hercegovina). Inductively coupled plasma mass spectrometry (ICP-MS) measurements show the presence of high concentration of uranium in some samples. Concentration of uranium in moss samples ranged from 5.2 - 755.43 Bq/Kg. We have determined U-235/U-238 isotope ratio using thermal ionization mass spectrometry (TIMS) front the samples with high uranium content and the ratios are in the range of 0.002097-0.002380. TIMS measurement confirms presence of DU in some samples. However, we have not noticed any traces of DU in samples containing lesser amount of uranium or from any samples from the living environment of same area.

In this paper we summarize the results of our investigation of the moving localized structures in lattice like systems. Dynamics of discrete localized modes in cubic, cubic-quintic, saturable photorefractive lattice and in the Bose-Einstein condensate modelled by the nonpolynomial Schrodinger equation are considered in the framework of the Peierls-Nabarro barrier. Two approaches are numerically tested: free-energy approach and mapping analysis. We show that only the last one is appropriate.

In this paper we summarize the results of our investigation of the moving localized structures in lattice like systems. Dynamics of discrete localized modes in cubic, cubic-quintic, saturable photorefractive lattice and in the Bose-Einstein condensate modelled by the nonpolynomial Schrodinger equation are considered in the framework of the Peierls-Nabarro barrier. Two approaches are numerically tested: free-energy approach and mapping analysis. We show that only the last one is appropriate.

Lichen and Moss are widely used to assess the atmospheric pollution by heavy metals and radionuclides. In this paper, we report results of uranium and its isotope ratios using mass spectrometric measurements (followed by chemical separation procedure) for mosses, lichens and soil samples from a depleted uranium (DU) target site in western Balkan region. Samples were collected in 2003 from Han Pijesak (Republika Srpska in Bosnia and Hercegovina). Inductively coupled plasma mass spectrometry (ICP-MS) measurements show the presence of high concentration of uranium in some samples. Concentration of uranium in moss samples ranged from 5.2 - 755.43 Bq/Kg. We have determined U-235/U-238 isotope ratio using thermal ionization mass spectrometry (TIMS) front the samples with high uranium content and the ratios are in the range of 0.002097-0.002380. TIMS measurement confirms presence of DU in some samples. However, we have not noticed any traces of DU in samples containing lesser amount of uranium or from any samples from the living environment of same area.

Results on studies of molecular spectra emitted in the initial stages of fullerene formation during the processing of graphite powder in induction RF reactor and evaporation of graphite electrodes in arc reactor are presented in this paper. It was found that C-2 radicals were dominant molecular species in both plasmas. C-2 radicals have an important role in the process of fullerene synthesis. The rotational-vibrational temperatures of C-2 and CN species were calculated by fitting the experimental spectra to the simulated ones. The results of optical emission study of C-2 radicals generated in carbon arc plasma have shown that rotational temperature of C-2 species depends on carbon concentration and current intensity significantly. The optical emission study of induction RF plasma and SEM analysis of graphite powder before and after plasma treatment have shown that evaporation of the processed graphite powder depends on feed rate and composition of gas phase significantly. Based on the obtained results, it was concluded that in the plasma region CN radicals could be formed by the reaction of C-2 species with atomic nitrogen at smaller loads. At larger feed rate of graphite powder, CN species were produced by surface reaction of the hot carbon particles with nitrogen atoms. The presence of nitrogen in induction RF plasma reduces the fullerene yield significantly. The fullerene yield obtained in two different reactors was: 13% in arc reactor and 4.1% in induction RF reactor. However, the fullerene production rate was higher in induction RIF reactor-6.4 g/h versus 1.7 g/h in arc reactor.

A part of incident energy is absorbed within the irradiated sample when a solid is exposed to the influence of laser radiation, to more general electromagnetic radiation within the wide range of wavelengths (from microwaves, to infrared radiation to X-rays), or to the energy of particle beams (electronic, protonic, or ionic). The absorption process signifies a highly selective excitation of the electronic state of atoms or molecules, followed by thermal and non-thermal de-excitation processes. Non-radiation de-excitation-relaxation processes induce direct sample heating. In addition, a great number of non-thermal processes (e.g., photoluminescence, photochemistry, photovoltage) may also induce heat generation as a secondary process. This method of producing heat is called the photothermal effect. The photothermal effect and subsequent propagation of thermal waves on the surface and in the volume of the solid absorbing the exciting beam may produce the following: variations in the temperature on the surfaces of the sample; deformation and displacement of surfaces; secondary infrared radiation (photothermal radiation); the formation of the gradient of the refractivity index; changes in coefficients of reflection and absorbtion; the generation of sound (photoacoustic generation), etc. These phenomena may be used in the investigation and measurement of various material properties since the profile and magnitude of the generated signal depend upon the nature of material absorbing radiation. A series of non-destructive spectroscopic, microscopic and defectoscopic detecting techniques, called photothermal methods, is developed on the basis of the above-mentioned phenomena. This paper outlines the interaction between the intensity modulated laser beam and solids, and presents a mathematical model of generated thermal sources. Generalized models for a photothermal response of optically excited materials have been obtained, including thermal memory influence on the propagatio

Results on studies of molecular spectra emitted in the initial stages of fullerene formation during the processing of graphite powder in induction RF reactor and evaporation of graphite electrodes in arc reactor are presented in this paper. It was found that C-2 radicals were dominant molecular species in both plasmas. C-2 radicals have an important role in the process of fullerene synthesis. The rotational-vibrational temperatures of C-2 and CN species were calculated by fitting the experimental spectra to the simulated ones. The results of optical emission study of C-2 radicals generated in carbon arc plasma have shown that rotational temperature of C-2 species depends on carbon concentration and current intensity significantly. The optical emission study of induction RF plasma and SEM analysis of graphite powder before and after plasma treatment have shown that evaporation of the processed graphite powder depends on feed rate and composition of gas phase significantly. Based on the obtained results, it was concluded that in the plasma region CN radicals could be formed by the reaction of C-2 species with atomic nitrogen at smaller loads. At larger feed rate of graphite powder, CN species were produced by surface reaction of the hot carbon particles with nitrogen atoms. The presence of nitrogen in induction RF plasma reduces the fullerene yield significantly. The fullerene yield obtained in two different reactors was: 13% in arc reactor and 4.1% in induction RF reactor. However, the fullerene production rate was higher in induction RIF reactor-6.4 g/h versus 1.7 g/h in arc reactor.

Electron cyclotron resonance ion sources (ECRIS) have been used primarily as injectors for cyclotrons and linear accelerators. Significant improvement of their performance iii the last two decades and substantial reduction of their price and running cost have opened the new fields of their application. In this paper we describe the applications of ECRIS in the field of surface modification of materials, which represent a relatively novel approach. The major advantages of these sources when compared to other sources applied in this field are: production of multiply charged ions, wide range of ion species obtained from gaseous and solid substances, and uninterrupted stable operation in a long period of time. New types of low power consumption ECR ion sources, with the magnetic structure made entirely of permanent magnets, are well suited for the applications using high voltage platforms, e.g., for ion implantation.

Electron cyclotron resonance ion sources (ECRIS) have been used primarily as injectors for cyclotrons and linear accelerators. Significant improvement of their performance iii the last two decades and substantial reduction of their price and running cost have opened the new fields of their application. In this paper we describe the applications of ECRIS in the field of surface modification of materials, which represent a relatively novel approach. The major advantages of these sources when compared to other sources applied in this field are: production of multiply charged ions, wide range of ion species obtained from gaseous and solid substances, and uninterrupted stable operation in a long period of time. New types of low power consumption ECR ion sources, with the magnetic structure made entirely of permanent magnets, are well suited for the applications using high voltage platforms, e.g., for ion implantation.

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