Enthalpy Probe Diagnostics of Steam/Argon Plasma Jet

DC plasma torch with argon/water stabilization features extreme properties of the exiting plasma jet. The plasma mass flow rate is very low while the temperature reaches very high values. Plasma properties were measured by enthalpy probe connected to a mass spectrometer. The measurements of enthalpy, temperature, density and dynamic pressure were carried out for three different arc currents and at atmos-pheric pressure. The dependences of plasma characteristics on arc current were shown

Diagnostics of Plasma Jet Generated in Water/Argon DC Arc Torch

Thermal plasma jet generated by the torch with water/argon stabilized arc was investigated. Plasma torches of this type have been used for plasma spraying, waste treatment and gasification of organic materials. Electric probes, enthalpy probe, and schlieren photography were used for diagnostics of the jet in the region downstream of the torch exit. Information about structure and shape of plasma jet was evaluated from the measured data. Large extent of radial plasma spread and high level of turbulence were found from both the schlieren and the probe diagnostics. Plasma temperature corresponding to measured ion saturation currents was determined using calculated composition of plasma assuming ex-istence of local thermodynamic equilibrium

Measurement of Copper Vapors in Water-Argon Thermal Plasma Jet

Plasma jet generated by water-argon plasma torch is enriched by copper evaporated from the anode sur-face. In this contribution we present results of measurement of emission spectral lines of neutral copper along the jet. We are able to monitor presence of copper vapors in the jet and in addition we use copper lines to obtain excitation temperature. This temperature seems to represent kinetic temperature of turbu-lent downstream regions of the jet with good accuracy

Study of the work roll cooling in hot rolling process with regard on service life

Operational conditions and many studies confirmed that the work rolls cooling in hot rolling process havesignificant impact on damage and service life. The specific approach based on the numerical simulation andexperimental results of the work roll cooling optimization and service life improvement is presented in this paper.The 3D finite element model was prepared for the numerical simulations of the work roll cooling. The FE modelrepresents circular sector of the work roll. The model is fully parametric. It is capable to simulate a roll with anydiameter, any thickness. Each of the model parameters can be easily changed based on user requirements. Thestress state is calculated by ANSYS in two steps. At first, the thermal conditions as starting temperature of the roll,cooling intensity and so on are applied and time dependent thermal analysis is performed. The temperature fieldof work roll is obtained from transient thermal analysis and is used as thermal loads in second step. In the secondstep structural analysis is carried out. The other relevant boundary conditions as normal, shear and contactpressure are considered in structural analysis. The Tselikov load distribution model is used for normal and shearstress distribution in a rolling gap. The boundary conditions for FE analysis are prepared in software MATLAB. Allconsidered boundary conditions are based on real measured data from hot rolling mills.The results of the performed analyses are focused on the description of the assessing methodology of the workrolls cooling on the stresses, deformations and service life of the rolls

The bright optical flash from GRB 060117

We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.Comment: Accepted to A&A, 4 pages, corected few typos pointed out by X.F. W

Calculation of the stresses in the tapered FGM beams with varying stiffness

The authors gratefully acknowledge financial support by the Slovak Grant Agency of the project VEGA No. 1/0416/21 and by the Slovak Research and Development Agency under Contract no. APVV-19-0406

Kinematic and constitutive equations in warping torsion of FGMs beams with spatially varying material properties

The authors gratefully acknowledge financial support by the Slovak Grant Agency of the project VEGA No. 1/0416/21 and by the Slovak Research and Development Agency under Contract no. APVV-19-040

A search for point sources of EeV photons

Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical Journa

Reconstruction of inclined air showers detected with the Pierre Auger Observatory

We describe the method devised to reconstruct inclined cosmic-ray air showers with zenith angles greater than $60^\circ$ detected with the surface array of the Pierre Auger Observatory. The measured signals at the ground level are fitted to muon density distributions predicted with atmospheric cascade models to obtain the relative shower size as an overall normalization parameter. The method is evaluated using simulated showers to test its performance. The energy of the cosmic rays is calibrated using a sub-sample of events reconstructed with both the fluorescence and surface array techniques. The reconstruction method described here provides the basis of complementary analyses including an independent measurement of the energy spectrum of ultra-high energy cosmic rays using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of Cosmology and Astroparticle Physics (JCAP