Utjecaj ultrazvučnog tretmana na strukturu visokougljičnog čelika

Discussion on the results of industrial tests of sound amplification of high-carbon steel in a 130 kg ingot mould. The sound amplification was conducted using a waveguide immersed in liquid steel and connected with a piezoelectric head excited acoustically with a power oscillator. The ultrasonic treatment had several purposes, one of which was inducing motion in the liquid steel during solidification. As result of the tests conducted, it was determined that, in ingots submitted to ultrasonic treatment compared with the ingots solidifying without, the axial segregation of elements was reduced and the share of the equiaxed zone in the area of acoustic wave impact increased by several percent.Rasprava rezultata industrijskog ispitivanja ultrazvuka kod visokougljičnog čelika u 130 kg ingotu. Pojačavanje zvuka je provedeno korištenjem ultrazvučnog provodnika uronjenog u tekući čelik, spojenog s piezoelektričnom glavom pobuđenom akustički s oscilatorom. Ultrazvučni tretman ima nekoliko svrha, od kojih je jedna induciranje gibanja u tekućem čeliku tijekom skrućivanja. Rezultati provedenog testa pokazali su da ingoti izloženi ultrazvučnom tretmanu u usporedbi s onim koji skrućavaju bez ultrazvučnog tretmana, imaju smanjenje aksijalnih segregacija od nekoliko posto

Research perspectives in the field of acoustic treatment of liquid alloys of iron

One of significant factors affecting properties of steel is uniform distribution of non-metallic inclusions and alloy elements across the steel product cross-section. Acoustic treatment may be the final technological stage enabling the quality of steel to be influenced. Further research to be undertaken in this field should be focused on the design of power heads with application of a stack of several piezoceramic elements or what is referred to as a mosaic head, or consisting in simultaneous use of several heads. What is additionally required is to determine ranges of parameters of the acoustic treatment process for individual groups of steel grades

Nuclear shell evolution and in-medium NN interaction

We report on a quantitative study of the evolution of the nuclear shell structure, in particular, effective single-particle energies (ESPEs), based on the spin-tensor decomposition of an effective two-body shell-model interaction. While the global trend of the ESPEs is mainly due to the central term of the effective interaction, variations of shell gaps invoke various components of the in-medium NN force. From a detailed analysis of a well-fitted realistic interaction in the sdpf shell-model space, two most important contributions for the evolution of the N = 20 and N = 28 shell gaps are confirmed to be the central term and the tensor term. The role of the latter is dominant to explain the energy shift of spin-orbit partners. Spin-tensor analysis of microscopic effective interactions in sd, pf, and gds shell-model spaces, contrasted with that of the phenomenologically adjusted ones, shows no evidence of amplification of the tensor component contribution; however, it points toward the neglect of three-body forces in the present microscopic interactions

The Nuclear Shell Model Toward the Drip Lines

We describe the "islands of inversion" that occur when approaching the neutron drip line around the magic numbers N=20, N=28 and N=40 in the framework of the Interacting Shell Model in very large valence spaces. We explain these configuration inversions (and the associated shape transitions) as the result of the competition between the spherical mean field (monopole) which favors magicity and the correlations (multipole) which favor deformed intruder states. We also show that the N=20 and N=28 islands are in reallity a single one, which for the Magnesium isotopes is limited by N=18 and N=32.Comment: Proceedings of the Nordic Conference in Nuclear Physics 2011, Stockholm, to appear in Physica Script

Opcije rabljenja čeličanske prašine u nemetalurškoj industriji

Recycling of by-products of the steelmaking process in electric arc (EAF) furnaces is an important activity from the perspective of environmental protection as well as the steelmaking industry itself. This article is a discussion concerning the selected research results in terms of utilisation of steelmaking dusts containing 4 - 12 % of zinc in manufacture of cement bricks, ceramic construction materials as well as colored glass products. The research conducted has implied that using steelmaking dusts in non-metallurgical industries is both possible and reasonable.Recikliranje nus proizvoda čeličanskih procesa u elektro lučnim pećima (ELP) je važna aktivnost sa gledišta zaštite okoliša kao i osobno za čeličansku industriju. Ovaj članak se tiče rasprave selektivnih rezultata istraživanja sa gledišta rabljene čeličanske prašine sa sadržajem 4-12 % cinka pri proizvodnji cementnih blokova, keramičkih materijala kao i obojenih staklenih proizvoda. Provedena istraživanja su ukazala da rabljenje čeličanske prašine u nemetalurškoj industriji je moguće i razborito

Qualitative characteristics of foundry dusts

Recycling has become a top priority research task in highly developed countries, addressed from the perspective of environmental protection as well as cost-effectiveness of products. In many countries, including Poland, landfilling is still commonly accepted as a method of choice for waste neutralisation. This paper presents results of studies on the environmental impact of iron-bearing foundry waste in the event of its landfill disposal

Determination of physico-chemical properties of fine-grained waste from the cleaning of iron casting

In the European Union one of the most important activities is the recovery and recycling of waste including foundry waste. In the article waste arising from production of iron casting was presented. Selected physic-chemical properties of iron-bearing waste were defined. Opportunities of waste management are related to their chemical construction as well as some physical properties. On the basic the results of research the solutions of foundry waste management were proposed

Determination of physico-chemical properties of fine-grained waste from the cleaning of iron casting

In the European Union one of the most important activities is the recovery and recycling of waste including foundry waste. In the article waste arising from production of iron casting was presented. Selected physic-chemical properties of iron-bearing waste were defined. Opportunities of waste management are related to their chemical construction as well as some physical properties. On the basic the results of research the solutions of foundry waste management were proposed

Storm impacts on hydrodynamics and suspended-sediment fluxes in a microtidal back-barrier estuary

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marine Geology 404 (2018): 1-14, doi:10.1016/j.margeo.2018.06.016.Recent major storms have piqued interest in understanding the responses of estuarine hydrodynamics and sediment transport to these events. To that end, flow velocity, wave characteristics, and suspended-sediment concentration (SSC) were measured for 11 months at eight locations in Chincoteague Bay, MD/VA, USA, a shallow back-barrier estuary. Daily breezes and episodic storms generated sediment-resuspending waves and modified the flow velocity at all sites, which occupied channel, shoal, and sheltered-bay environments with different bed-sediment characteristics. Despite comparable SSC during calm periods, SSC at the channel locations was considerably greater than at the shoal sites during windy periods because of relatively more erodible bed sediment in the channels. Sediment fluxes were strongly wind modulated: within the bay's main channel, depth-integrated unit-width sediment flux increased nonlinearly with increasing wind speed. When averaged over all sites, about 35% of the flux occurred during windy periods (wind speed greater than 6 m s−1), which represented just 15% of the deployment time. At channel sites, the net water and sediment fluxes were opposite to the direction of the wind forcing, while at shoal sites, the fluxes generally were aligned with the wind, implying complex channel–shoal dynamics. Yearly sediment fluxes exceed previous estimates of sediment delivery to the entirety of Chincoteague Bay. These observations illustrate the dynamic sedimentary processes occurring within microtidal back-barrier lagoons and highlight the importance of storm events in the hydrodynamics and overall sediment budgets of these systems.his study was part of the Estuarine Physical Response to Storms project (GS2-2D), supported by the Department of the Interior Hurricane Sandy Recovery program

Sediment dynamics of a divergent bay-marsh complex

Author Posting. © Springer Nature , 2020. This article is posted here by permission of Springer Nature for personal use, not for redistribution. The definitive version was published in Nowacki, D. J., & Ganju, N. K. Sediment dynamics of a divergent bay-marsh complex. Estuaries and Coasts, (2020), doi:10.1007/s12237-020-00855-5.Bay–marsh systems, composed of an embayment surrounded by fringing marsh incised by tidal channels, are widely distributed coastal environments. External sediment availability, marsh-edge erosion, and sea-level rise acting on such bay–marsh complexes may drive diverse sediment-flux regimes. These factors reinforce the ephemeral and dynamic nature of fringing marshes: material released by marsh-edge erosion becomes part of a bay–marsh exchange that fuels the geomorphic evolution of the coupled system. The dynamics of this sediment exchange determine the balance among seaward export, deposition on the embayment seabed, flux into tidal channels, and import to the marsh platform. In this work, we investigate the sediment dynamics of a transgressive bay–marsh complex and link them to larger-scale considerations of its geomorphic trajectory. Grand Bay, Alabama/Mississippi, is a shallow microtidal embayment surrounded by salt marshes with lateral erosion rates of up to 5 m year−1. We collected 6 months of oceanographic data at four moorings within Grand Bay and its tidal channels to assess hydrographic conditions and net sediment-flux patterns and augmented the observations with numerical modeling. The observations imply a divergent sedimentary system in which a majority of the suspended sediment is exported seaward, while a smaller fraction is imported landward via tidal channels, assisting in vertical marsh-plain accumulation, maintenance of channel and intertidal-flat morphologies, and landward transgression. These results describe a dynamic system that is responsive to episodic atmospheric forcing in the absence of a strong tidal signal and the presence of severe lateral marsh loss.We thank the staff of the Grand Bay NERR for their role in facilitating fieldwork within Grand Bay. Jonathan Pitchford, also of the Grand Bay NERR, provided the SET data. Giulio Mariotti and an anonymous reviewer are acknowledged for their helpful comments