From Henry Bessemer’s invention to comprehensive converter process optimization

The Bessemer process enabling to produce high-quality steels was implemented at steel mills of the Urals region more than 200 years ago. At the beginning of the 20th century, the process was modified by scientists from the Mining Institute and was then adopted by copper and nickel alloy producers. The converter process became one of the key processing stages with Russian copper and nickel smelters. This paper examines certain ways to improve the tuyere air flow in a horizontal converter. The authors came up with a generic equation for calculating specific blast air pressure and discuss the use of hydrothermal and aerodynamic techniques for tuyere purging. The blast air limit was determined for a horizontal converter that is characterized with massive melt ejections. The authors demonstrate that, in spite of all the process and design improvements, the modern converter process still has three major drawbacks. They include process cycling, the gas ductwork not being completely tight, unbalanced thermal and chemical status of the vessel leading to excessive thermal and chemical loads on the tuyere zone and incomplete slag formation in zones that are farther from the tuyeres. Research work is ongoing on a novel continuous converter design which involves the use of special-design unsubmerged tuyeres. Such tuyeres produce spatially oriented high-pressure blasts which enable consistent rotation of the molten matte in a tight cylindrical vessel.

Gravitational production of vector dark matter

A model of vector dark matter that communicates with the Standard Model only through gravitational interactions has been investigated. It has been shown in detail how does the canonical quantization of the vector field in varying FLRW geometry implies a tachyonic enhancement of some of its momentum modes. Approximate solutions of the mode equation have been found and verified against exact numerical ones. De Sitter geometry has been assumed during inflation while after inflation a non-standard cosmological era of reheating with a generic equation of state has been adopted which is followed by the radiation-dominated universe. It has been shown that the spectrum of dark vectors produced gravitationally is centered around a characteristic comoving momentum k⋆ that is determined in terms of the mass of the vector mX, the Hubble parameter during in- flation HI, the equation of state parameter w and the efficiency of reheating γ. Regions in the parameter space consistent with the observed dark matter relic abundance have been determined, justifying the gravitational production as a viable mechanism for vector dark matter. The results obtained in this paper are applicable within various possible models of inflation/reheating with non-standard cosmology parametrized effectively by the corresponding equation of state and efficiency of reheating.

Two Temperature Extension of Phonon Hydrodynamics

Phonon hydrodynamics uses the fields of the total energy and the heat flux as state variables. We extend it by promoting the microscopic internal energy field into the status of an extra independent state variable. The governing equations of both the phonon and the extended (two temperature) phonon hydrodynamics are formulated as particular realizations of the abstract GENERIC equation. Such unified formulation makes both theories manifestly compatible with mechanics and thermodynamics. Also differences and similarities (in the physical content, in the mathematical structure, and in qualitative properties of solutions) between the two heat transfer theories, as well as their mutual compatibility, become manifestly displayed.

Stable thin-shells from 5-dimensional extremal Einstein–Yang–Mills fields

By employing exact Einstein–Yang–Mills (EYM) solution in [Formula: see text] dimensions we establish spherical thin-shells with mass and Yang–Mills charge. Remarkably these shells are stable against linear, radial perturbations with a barotropic fluid presented on the shell with a generic equation of state [Formula: see text] supporting the speed of sound [Formula: see text].

Modeling of Capacitance in A Supercapacitor

A general supercapacitor model is developed by incorporating the effective surface area in the presence of pores. An analytical solution has been derived from the generic equation in Laplace domain based on the porous-electrode theory. This model demonstrates the effects of solution to matrix conductivity ratio, separator to electrode resistance ratio and discharge current density on the electrochemical impedance, capacitance and energy density of supercapacitor. The electrochemical impedance, capacitance and energy density of supercapacitor are calculated in this work. The maximum capacitance of 12.71 F/cm2was computed in low frequency range in this device. The proposed model can be applied to simulate the characteristics of polymer-based supercapacitor in near future.

Biomass Equations for Tropical Tree Plantation Species in Young Stands Using Secondary Data from the Philippines

Estimation of the magnitude of sinks and sources of carbon requires reliable estimates of the biomass of forests and of individual trees. Equations for predicting tree biomass have been developed using secondary data involving destructive sampling in plantations (mostly less than 10 years of age) in several localities in the Philippines. These equations allow estimates of carbon sequestration to be made at much lower cost than would be incurred if detailed stand inventories were undertaken. The species included in the study reported here include Gmelina arborea Roxb., Paraserianthes falcataria (L.) Nielsen Swietenia macrophylla King and Dipterocarp species in Mindanao, and Leucaena leucocephala de Wit from Laguna, Antique, Cebu, Iloilo, Rizal, and Ilocos Sur. Non-linear regression was used to derive speciesspecific, site specific and generic equations between yield and diameter of the form y = αDβ. Equations were evaluated based on the correlation coefficient, standard error of estimate and residual plots. Regressions resulted in high r values (>0.90). In some cases, non-homogeneous variance was encountered. The generic equation improved estimates compared with models used in previous studies.

New Generic Equation for Interaction Effects on a Moored Containership Due to a Passing Tanker

In order to improve the formulation of moored-passing ship interaction forces and moments in the mathematical model of a ship maneuvering simulator, a comprehensive captive model test program was carried out and a theoretical calculation method was developed. At present, semiempirical approaches, resulting in an estimation of forces and moments in the horizontal plane caused by hydrodynamic interaction on a moored ship due to a passing ship, are not available in literature. The present research intends to enhance the theoretical approach by validating the calculated peak forces and moments with experimental data. The numerical method is subsequently applied to generate a systematic database for the development of a new set of generic formulae for estimating the effect of passing vessels on moored ships in the equations of motion for surge, sway, and yaw applied in maneuvering and moor-ing simulators.