Istraživanje segregacije bora kod niskougljičnih čelika

Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C steel with 0,006 % boron. Investigations were carried out for temperature 1300 – 700°C and cooling rates from 1°C/s to 100°C/s. The changes of boron concentrations in austenite and ferrite after commencement of γ→α phase transformation were established.Tragovi bora u rasponu 0,002-0,009 % se obično dodaju mnogim tipovima čelika. Utjecaj bora na fazne transformacije i zakaljivost niskougljičnih niskolegiranih čelika ovisi o obliku njegovog ponašanja u čvrstoj otpini ili u segregacijama ili u precipitatima. Temperatura i brzina hlađenja određuju postojanje segregacija bora na granicama zrna. U ovom radu simulacije koncentracija bora su proračunate pomoću kompjutorskog programa DICTRA za niskougljični čelik s 0,08 % C i 0,006 % bora. Istraživanja su provedena ta temperature 1 300–700°C i brzine hlađenja od 1°C/s do 100°C/s. Utvrđene su promjene koncentracije bora u austenitu i feritu nakon početka γ→α fazne transformacije

Istraživanje segregacije bora kod niskougljičnih čelika

Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C steel with 0,006 % boron. Investigations were carried out for temperature 1300 – 700°C and cooling rates from 1°C/s to 100°C/s. The changes of boron concentrations in austenite and ferrite after commencement of γ→α phase transformation were established.Tragovi bora u rasponu 0,002-0,009 % se obično dodaju mnogim tipovima čelika. Utjecaj bora na fazne transformacije i zakaljivost niskougljičnih niskolegiranih čelika ovisi o obliku njegovog ponašanja u čvrstoj otpini ili u segregacijama ili u precipitatima. Temperatura i brzina hlađenja određuju postojanje segregacija bora na granicama zrna. U ovom radu simulacije koncentracija bora su proračunate pomoću kompjutorskog programa DICTRA za niskougljični čelik s 0,08 % C i 0,006 % bora. Istraživanja su provedena ta temperature 1 300–700°C i brzine hlađenja od 1°C/s do 100°C/s. Utvrđene su promjene koncentracije bora u austenitu i feritu nakon početka γ→α fazne transformacije

Submillimeter Imaging of NGC 891 with SHARC

The advent of submillimeter wavelength array cameras operating on large ground-based telescopes is revolutionizing imaging at these wavelengths, enabling high-resolution submillimeter surveys of dust emission in star-forming regions and galaxies. Here we present a recent 350 micron image of the edge-on galaxy NGC 891, which was obtained with the Submillimeter High Angular Resolution Camera (SHARC) at the Caltech Submillimeter Observatory (CSO). We find that high resolution submillimeter data is a vital complement to shorter wavelength satellite data, which enables a reliable separation of the cold dust component seen at millimeter wavelengths from the warmer component which dominates the far-infrared (FIR) luminosity.Comment: 4 pages LaTeX, 2 EPS figures, with PASPconf.sty; to appear in "Astrophysics with Infrared Surveys: A Prelude to SIRTF

Multi-agent system for dynamic manufacturing system optimization

This paper deals with the application of multi-agent system concept for optimization of dynamic uncertain process. These problems are known to have a computationally demanding objective function, which could turn to be infeasible when large problems are considered. Therefore, fast approximations to the objective function are required. This paper employs bundle of intelligent systems algorithms tied together in a multi-agent system. In order to demonstrate the system, a metal reheat furnace scheduling problem is adopted for highly demanded optimization problem. The proposed multi-agent approach has been evaluated for different settings of the reheat furnace scheduling problem. Particle Swarm Optimization, Genetic Algorithm with different classic and advanced versions: GA with chromosome differentiation, Age GA, and Sexual GA, and finally a Mimetic GA, which is based on combining the GA as a global optimizer and the PSO as a local optimizer. Experimentation has been performed to validate the multi-agent system on the reheat furnace scheduling problem

Effect of a skin-deep surface zone on formation of two-dimensional electron gas at a semiconductor surface

Two dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a 1D self-consistent Poisson-Schr\"{o}dinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schr\"{o}dinger scheme predicts the 2DEG bands energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wavefunctions.Comment: 9 pages, 7 figures, 2 table