Growth characteristics of spherical titanium oxide nanoparticles during the rapid gaseous detonation reaction

The nanosize grain growth characteristics of spherical single-crystal titanium oxide (TiO₂) during the rapid gaseous detonation reaction are discussed. Based on the experimental conditions and the Chapman–Jouguet theory, the Kruis model was introduced to simulate the growth characteristics of spherical TiO₂ nanoparticles obtained under high pressure, high temperature and by rapid reaction. The results show that the numerical analysis can satisfactorily predict the growth characteristics of spherical TiO₂ nanoparticles with diameters of 15–300 nm at different affecting factors, such as concentration of particles, reaction temperature and time, which are in agreement with the obtained experimental results. We found that the increase of the gas-phase reaction temperature, time, and particle concentration affects the growth tendency of spherical nanocrystal TiO₂, which provides effective theoretical support for the controllable synthesis of multi-scale nanoparticles.     

Experimental study and numerical modeling of brittle fracture of carbonate rock under uniaxial compression

The brittle carbonate rock taken from the Tarim Oilfield is tested in laboratory under uniaxial compression. The acoustic emission (AE) is used to monitor the microcracking activity in rock during the experiment. Moreover, the 3D tomograms of carbonate rock after uniaxial compression are obtained by using CT imaging technology, which indicates that microcracks mutually interconnect and eventually form macroscopic fractures after failure. The PFC2D is used to model the behavior of brittle rock including microcracks propagation. The stress–strain curve and cracks distribution in rock model are obtained from the PFC simulation. The numerical results agree with the experimental test well.     

A two dimensional Euler–Lagrangian model of wood gasification in a charcoal bed—Part II: Parameter influence and comparison

A Euler–Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle–particle and particle–wall collisions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study (Gerber & Oevermann, 2014). The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with different sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle–particle and particle–wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reactor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.     

Continuous segregation of binary heterogeneous solids in a fast-fluidized bed

Continuous segregation of binary heterogeneous solids (different density mixtures) is carried out in a gas–solid fluidized bed to study the effects of gas velocity, solids feed rate, feed composition and density difference of solids on the separation factor (recovery of flotsam at top outlet) and the quality of the product (purity of flotsam at top outlet) in a continuous fast-fluidized bed. The holdup of the bed material is obtained in each experimental run. It is observed that the separation factor decreases with increase in solids feed rate or density difference of solids, and increases with gas velocity or proportion of flotsam in the feed. The quality of the product decreases with increase in gas velocity or solids flow rate, and increases with feed composition or density difference of solids. The experimental results show that the separation factor and the quality of the product are more sensitive to gas velocity than to other operating parameters. Empirical correlations for predicting the separation factor and quality of the product are proposed based on the Richards model for individual flotsam mass fraction in the feed, and the predictions agree satisfactorily with the present experimental data.     

Energy dependence on modes of electric activities of neuron driven by multi-channel signals

Nonlinear Dynamics - Neuron can receive electric signals or forcing currents from more than one channel, and these forcing currents could show some diversity. Based on the Hindmarsh–Rose...     

On Signed Star Domination in Graphs

Acta Mathematicae Applicatae Sinica, English Series - For a graph G = (V, E) without isolated vertex, a function f: E(G) → {−1, 1} is said to be a signed star dominating function of G...     

Phase transition layers with boundary intersection for an inhomogeneous Allen–Cahn equation

We consider the nonlinear problem of inhomogeneous Allen–Cahn equation

${?}^2\mathrm{\Delta }u+V(y)u(1?u^2)=0\text{in}\mathrm{\Omega },\frac{?u}{?\nu }=0\text{on}?\mathrm{\Omega },$

where Ω is a bounded domain in ${\mathbb{R}}^2$ with smooth boundary, ? is a small positive parameter, ν denotes the unit outward normal of ?Ω, V is a positive smooth function on $\overline{\mathrm{\Omega }}$. Let Γ be a curve intersecting orthogonally with ?Ω at exactly two points and dividing Ω into two parts. Moreover, Γ satisfies stationary and non-degenerate conditions with respect to the functional ${\int }_{\mathrm{\Gamma }}{V}^{1/2}$. We can prove that there exists a solution $u_{?}$ such that: as $?\to 0$, $u_{?}$ approaches +1 in one part of Ω, while tends to ?1 in the other part, except a small neighborhood of Γ.     

On the simplicity of induced modules for reductive Lie algebras II

An open problem proposed by Friedlander and Parshall is considered. A sufficient condition is given for the simplicity of induced modules of reductive Lie algebras.     

Room temperature ionic liquid electrolytes for redox flow batteries

Redox flow batteries (RFBs) usually contain aqueous or organic electrolytes. The aim of this communication is to explore the suitability of room temperature ionic liquids (RTILs) as solvents for RFBs containing metal complexes. Towards this aim, the electrochemistry of the metal acetylacetonate (acac) complexes Mn(acac)₃, Cr(acac)₃, and V(acac)₃ was studied in imidazolium-based RTILs. The V²⁺/V³⁺, V³⁺/V⁴⁺, and V⁴⁺/V⁵⁺ redox couples are quasi-reversible in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [C₂C₁Im][N(Tf₂)]. The Mn(acac)₃ and Cr(acac)₃ voltammetry, on the other hand, is irreversible in [C₂C₁Im][N(Tf₂)] at glassy carbon (GC) but the rate of the Mn²⁺/Mn³⁺ reaction increases if Au electrodes are used. Charge–discharge measurements show that a coulombic efficiency of 72% is achievable using a V(acac)₃/[C₂C₁Im][N(Tf₂)]/GC cell.