STUDY ON ENERGY EFFICIENCY OF A-TIG WELDING OF STAINLESS STEELS USING INDIVIDUAL FLUX-OXIDES. PART 2. INFLUENCE OF THERMODYNAMIC AND PHYSICO-CHEMICAL PROPERTIES OF FLUX-OXIDES

This paper presents the results of studies on the influence of thermodynamic and physico-chemical properties of individual flux-oxides on the energy efficiency of the arc A-TIG welding of stainless steel CrNi18-10. The obtained results of the research allowed to reveal the criteria for evaluating the energy efficiency of the arc A-TIG welding on the depth of penetration of the welded metal and to determine the impact of thermodynamic and physico-chemical properties of individual flux oxides on the energy efficiency of the penetration capability of the welding arc for different welding energies. The requirements to thermodynamic and physico-chemical properties of individual fluxes-oxides are also revealed, which provide high energy efficiency of arc penetration capability during A-TIG welding.

STUDY ON A-TIG WELDING ENERGY EFFICIENCY OF STAINLESS STEELS USING INDIVIDUAL FLUX-OXIDES Part 1: EVALUATION OF THE A-TIG ARC ENERGY EFFICIENCY TO THE WELD DEPTH OF PENETRATION

This article presents the results of the study of activating oxide fluxes effects on the energy efficiency of the TIG welding arc (A-TIG) influence. This efficiency was estimated by the amount of energy spent by the arc (q) at the depth of penetration (P). It is revealed that the arc energy efficiency factor “Kepac” can be used as an indicator of the influence of arc energy on the efficiency of penetration of the welded metal, which is determined by the ratio of spent energy per unit of depth of penetration (q/P) at TIG and A-TIG welding. In accordance with the results of the research, it is observed an increase of the energy efficiency on the welding arc penetration capability of all individual oxides used as fluxes in A-TIG welding is observed. Among them, the greatest energy efficiency of the arc process on the penetration of CrNi18-10 steel is observed when oxides such as TiO2, SiO2, Cr2O3 and Co3O4 are used.

The Suppression and Promotion of Magnetic Flux Emergence in Fully Convective Stars

Evidence of surface magnetism is now observed on an increasing number of cool stars. The detailed manner by which dynamo-generated magnetic fields giving rise to starspots traverse the convection zone still remains unclear. Some insight into this flux emergence mechanism has been gained by assuming bundles of magnetic field can be represented by idealized thin flux tubes (TFTs). Weber & Browning (2016) have recently investigated how individual flux tubes might evolve in a 0.3M⊙ M dwarf by effectively embedding TFTs in time-dependent flows representative of a fully convective star. We expand upon this work by initiating flux tubes at various depths in the upper ~50-75% of the star in order to sample the differing convective flow pattern and differential rotation across this region. Specifically, we comment on the role of differential rotation and time-varying flows in both the suppression and promotion of the magnetic flux emergence process.

Modeling of Drift Effects on Solar Tower Concentrated Flux Distributions

A novel modeling tool for calculation of central receiver concentrated flux distributions is presented, which takes into account drift effects. This tool is based on a drift model that includes different geometrical error sources in a rigorous manner and on a simple analytic approximation for the individual flux distribution of a heliostat. The model is applied to a group of heliostats of a real field to obtain the resulting flux distribution and its variation along the day. The distributions differ strongly from those obtained assuming the ideal case without drift or a case with a Gaussian tracking error function. The time evolution of peak flux is also calculated to demonstrate the capabilities of the model. The evolution of this parameter also shows strong differences in comparison to the case without drift.

Near-simultaneous magnetotail flux rope observations with Cluster and Double Star

We present observations of three magnetic flux ropes in the tail of the Earth's magnetosphere on 7 August 2004 by the Cluster and Double Star TC-1 spacecraft. The first two flux rope signatures were observed, near-simultaneously, by Cluster and TC-1, which were located at (–16.3, –8.7, 0.10) RE GSM and (–10.3, –7.11, 0.81) RE GSM, respectively, a separation of 6.3 RE. A third signature was observed some four minutes later by two of the four Cluster spacecraft, while the other two spacecraft observed a feature resembling a Travelling Compression Region (TCR). These observations are interpreted as three individual flux ropes existing in the magnetotail, the first two, at least, simultaneously. The formation mechanism of the flux ropes and the consequences of their presence for the structure of the magnetotail on this day are discussed in the context of multiple X-point reconnection.

Theoretical Foucault Images of Superconducting Fluxons

Individual flux lines in superconducting specimens have been recently observed using a 300kV holography electron microscope equipped with a cold field emission gun in the transmission mode by means of the out-of-focus method. In this way it has been possible to observe the dynamic behaviour of fluxons depending upon the variations of the temperature and/or the applied magnetic field or current. The main disadvantage of this method is that correlation with structural defects is troublesome owing to the large defocus distance (of the order of 1 cm for conventional superconductors) necessary for the detection of flux lines.This drawback is not present in the Foucault technique, where the contrast is generated in the focused image by masking part of the transmitted beam by means of an aperture. Therefore, some preliminary calculations have been made recently using one-dimensional models, which allow for a quick and easy simulation of the factors affecting the experimental conditions .