In this study, a solid solution of arsenical ammonium-sodium jarosite, with the approximate formula [(NH4)0.72 Na0.06(H3O)0.21]Fe3(2.52)(SO4)1.85 (AsO4)0.15 [(OH)4.41 (H2O)1.59], was synthesized. The precipitate particle main size 38 µm, spherical morphology. A decomposition reaction in alkaline media carried out; comprised three stages: an induction period, progressive conversion and stabiliza...

The study presents a new modelling approach applied to hematite magnetite reduction, which is the dominant reaction in atmospheres with high CO2/CO ratio, expected chemical looping combustion. structure of Fe2O3 particle was simulated using percolation theory, while reduction modelled stochastic simulate nucleation, gaseous diffusion, solid-state and reaction. To account for differences between...

In this paper, we present a semi-analytical model for determining the magnetic and electromagnetic characteristics of spoke-type permanent magnet (STPM) machine considering magnet segmentation and finite soft-material relative permeability. The proposed model is based on the resolution of the Laplace’s and Poisson’s equations in a Cartesian pseudo-coordinate system with respect to the relative ...

In this paper, a new off-line model predictive control strategy is presented for a kind of linear parameter varying system with polytopic uncertainty. A nest of shrinking ellipsoids is constructed by solving linear matrix inequality. By splitting the objective function into two parts, the proposed strategy moves most computations off-line. The on-line computation is only calculating the current...

Phosphate rock has been considered as one of the most significant secondary rare-earth resource, and utilization rare earth elements (REEs) in phosphate attracted increasing attention. In this study, leaching kinetics REEs from a ore China was studied with variation temperature phosphoric acid concentration under conditions: ratio liquid to solid 12 mL/g, stirring speed 120 r/min, particle size...

We study the shrinking and separation properties (two notions well-known in descriptive set theory) for NP and coNP and show that under reasonable complexity-theoretic assumptions, both properties do not hold for NP and the shrinking property does not hold for coNP. In particular we obtain the following results. 1. NP and coNP do not have the shrinking property, unless PH is finite. In general,...

In this paper, measurements of the CO2 gasification kinetics for two types of Shenfu coal chars, which were respectively prepared by slow and rapid pyrolysis at temperatures of 950 °C and 1,400 °C, were performed by an isothermal thermo-gravimetric analysis under ambient pressure and elevated temperature conditions. Simultaneously, the applicability of the kinetic model for the CO2 gasification...

Aiming at region connection calculus (RCC) can only roughly represent spatial topological relations, and have difficulty in representing the distance, direction and so on. Therefore, based on RCC theory, Region Extension and Shrinking Calculus are proposed, and then a formalized metrization method using region as a basic unit is introduced. Based on RESC theory, taking the advantage such as app...

The mathematical model for the incompressible two-dimensional stagnation flow of a Maxwell fluid towards a shrinking sheet is proposed. The developed equations are used to discuss the problem of being two dimensional in the region of stagnation point over a shrinking sheet. The nonlinear partial differential equations are transformed to ordinary differential equations by firsttaking boundary-la...