Phase structure in the baryon density-dependent quark mass model

The properties of phase diagram of strange quark matter in equilibrium with hadronic matter at finite temperature are studied, where the quark phase and hadron phase are treated by baryon density-dependent quark mass model and hadron resonance gas model with hard core repulsion factor, respectively. Our results indicate that the strangeness fraction fs, perturbation parameter C, and confinement parameter D have strong influence on the properties of phase diagram and the formation of strangelets, where a large fs, small C and D favor the formation of strangelets. Consider the isentropic expansion process, we found that the initial entropy per baryon is about 5, which gives a large probability for the formation of strangelets. Furthermore, as the strangeness fraction fs and one gluon-exchange interaction strength C decrease and confinement parameter D increases, the reheating effect becomes more significant, reducing the possibility of forming strangelets. The new phase diagram could support a massive compact star with the maximum mass exceeding twice the solar mass and have a significant impact on the mass-radius relationship for hybrid stars

Optimal intelligent control for doubly fed induction generators

For the first time, a novel concept of merging computational intelligence (the type-2 fuzzy system) and control theory (optimal control) for regulator and reference tracking in doubly fed induction generators (DFIGs) is proposed in this study. The goal of the control system is the reference tracking of torque and stator reactive power. In this case, the type-2 fuzzy controller is activated to enhance the performance of the optimum control. For instance, in abrupt changes of the reference signal or uncertainty in the parameters, the type-2 fuzzy system performs a complementary function. Both parametric uncertainty and a perturbation signal are used to challenge the control system in the simulation. The findings demonstrate that the presence of a type-2 fuzzy system as an additional controller or compensator significantly enhances the control system. The root mean square error of the suggested method’s threshold was 0.012, quite acceptable for a control system

Tris[tris­(1,10-phenanthroline-κ2 N,N′)iron(II)] dodeca­tungstoferrate dihydrate

The title compound, [Fe(C12H8N2)3]3[FeW12O40]·2H2O, was prepared under hydro­thermal conditions. The discrete Keggin-type [FeW12O40]6− heteropolyoxoanion has threefold symmetry, with the FeII atom located on the threefold rotation axis. The central FeO4 tetra­hedron in the anion shares its O atoms with four W3O13 trinuclear units, each of which is made up of three edge-shared WO6 octa­hedral units. The FeII atom in the complex cation, viz [Fe(phen)3]2+ (phen is 1,10-phen­anthroline), shows a slightly distorted octa­hedral geometry defined by six N atoms from three phen ligands. The polyoxoanions pack together with the cations, with the disordered water mol­ecules located in voids; the site occupancy factor for each water O atom is 0.33

An ionic organic–inorganic hybrid: tetra­kis[bis­(1,10-phenanthroline)copper(I)] dodeca­tungstophosphate(V)

Single crystals of the title polyoxometallate-based organic–inorganic hybrid, [Cu(C12H8N2)2]4[SiW12O40], were grown under hydro­thermal conditions. The discrete [SiW12O40]4− anions are of the Keggin type and are packed in a slightly distorted ortho­rhom­bic F-centred mode, with the complex [CuI(phen)2]+ cations (phen is 1,10-phenanthroline) located in the voids of this arrangement. The four independent CuI cations are situated in the centres of more or less distorted tetra­hedra made up of N atoms from the phen ligands. The anions and cations are linked together via weak hydrogen-bonding inter­actions, forming an extended three-dimensional network. Additional stabilization is achieved via π–π inter­actions between different phen mol­ecules of adjacent [CuI(phen)2]+ cations with shortest distances between 3.416 and 3.499 Å

Numerical Simulation Study of Turbulent Flow in Vacuum Tempering Furnace Using K-Epsilon Model

Vacuum tempering furnace prevalence of uneven temperature problems. In this paper, numerical analyses for turbulent flow inside vacuum tempering furnace using k-ε turbulence model. The moving reference frame is helpful to improve the precision of the model. Not only the loading area and its adjacent components have an influence on temperature uniformity, but the shape of the auxiliary parts, the shape of the driving parts and the way of loading have an influence. The influence factors of turbulence are studied from multiple angles. Based on the factors, the combinatorial optimization scheme is proposed and temperature uniformity test is carried out. The results show that the shape of the fan blade, the inlet diameter of the gas guide tube, the shape of the centre channel and the shape of the wind scooper influences furnace temperature uniformity. The adjustment of loading area and the use of multiple central channels in equal area will not affect furnace temperature uniformity

CFD modeling of chemical looping combustion in fuel reactor with gaseous fuel

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Chemical looping combustion (CLC) as a potential CO2 capture technology has been considered as a promising and likely alternative to traditional combustion technology to mitigate the CO2 emission due to its prosecution of CO2 sequestration at a very low cost. In CLC, solid oxygen carriers are introduced to transfer the oxygen necessary for the combustion from air through the initial oxidation in air reactor and subsequent reduction in fuel reactor. The CLC unit utilized in this study is composed of two interconnected fluidized bed including a circulating fluidized bed as the air reactor and a bubbling fluidized bed as the fuel reactor. While a number of studies on the hydrodynamic behaviour of the CLC process in fuel reactor have been documented in the open literature, there have been limited studies on the correlation between the bubble formation and the local volume fraction. The hydrodynamic behaviours and reactive characteristics of oxygen carriers are still not fully understood although a variety of experiments and simulations have been performed. This paper aims to investigate the CLC process in a fuel reactor using the CFD modelling, coupled with the heterogeneous reactions and investigating the hydrodynamics and reaction kinetics of the CLC process in the fuel reactor. A parameter correlating the occurrence of bubble and dynamic parameters is proposed. The parameter can be acted as an indicator of time-dependent bubble evolution with a potential to be adopted in the CLC for controlling the bubbling phenomena since the occurrence of the bubbles at specific positions is highly correlated with the local large eddies embedded in the flow. The static bed height variations in the fuel reactor system affecting the flow behaviour and kinetics of the CLC process are also discussed. The results obtained from the CFD simulations indicate clearly that the CFD model developed in the current study reasonably forecasts the hydrodynamic behaviour and important phenomena observed in the fuel reactor.dc201