A new equivalent method to obtain the stoichiometric fuel-air cloud from the inhomogeneous cloud based on FLACS-dispersion

The fuel-air cloud resulting from an accidental discharge event is normally irregular in shape and varying in concentration. Performance of dispersion simulations using the computational fluid dynamics （CFD）-based tool FLACS can get an uneven and irregular cloud. For the performance of gas explosion study with FLACS, the equivalent stoichiometric fuel-air cloud concept is widely applied to get a representative distribution of explosion loads. The Q9 cloud model that is employed in FLACS is an equivalent fuel-air cloud representation, in which the laminar burning velocity with first order SL and volume expansion ratio are taken into consideration. However, during an explosion in congested areas, the main part of the combustion involves turbulent flame propagation. Hence, to give a more reasonable equivalent fuel-air size, the turbulent burning velocity must be taken into consideration. The paper presents a new equivalent cloud method using the turbulent burning velocity, which is described as a function of SL, deduced from the TNO multi- energy method.

Indirect-approach method for specified-end points seismic ray tracing in three dimen-sional inhomogeneous media

Generally speaking, the factors of both medium and tectonic that give rise to heterogeneity of the earth crust and mantle structures should be taken into account simultaneously in three dimensional seismic ray tracing. In this paper, the three dimensional structure models are constructed with the model similar to generation system in computer aid design and manufacturing (CAD/CAM). Based on the algorithm proposed by Cerveny et al . for complete seismic ray tracing in complex three dimensional structures, a new technique called the indirect approach method for two point seismic ray tracing in three dimensional laterally heterogeneous media has been put forward, and its numerical computing examples were given.

What are Different Research Approaches?Comprehensive Review of Qualitative,Quantitative,and Mixed Method Research,Their Applications,Types,and Limitations

There are different ways to examine and explain a study and its findings based on using numbers as a measure,a descriptive style,or a mixture of both.These three research approaches are quantitative,qualitative,and mixed methods that are commonly used by researchers in various research studies.However,with many options regarding the research design,it seems challenging for researchers to select the most appropriate approach based on the study and realize differences.This study provides a comprehensive review of qualitative,quantitative,and mixed-method research methods.Each method is clearly defined and specifically discussed based on applications,types,advantages,and limitations to help researchers identify select the most relevant type based on each study and navigate accordingly.

Examination of the poverty-environmental degradation nexus in Sub-Saharan Africa

The relationship between environmental degradation and poverty has increasingly become the focus of national strategic decision-making in recent years.However,despite several theoretical explorations on the nexus,a dearth of empirical literature on the poverty-environmental degradation nexus,specifically on Sub-Saharan Africa(SSA),still exists.In this study,we investigated the poverty-environmental degradation nexus in SSA.We hypothesized that poverty is both a cause and effect of environmental degradation,and this relationship is explained as a vicious cycle.Unlike previous studies,we employed several alternative indicators of environmental degradation to examine the poverty-environmental degradation nexus in this study.We used data from 41 countries of SSA between 1996 and 2019 and employed the generalized method of moments(GMM)approach.The findings suggest a cyclical relationship between poverty and environmental degradation in SSA,which confirms that an increase in poverty leads to an increase in environmental degradation,especially in deforestation and PM2.5 emissions.Similarly,the increase in environmental degradation positively affects poverty in SSA.We also confirmed that exogenous conditioning factors such as population growth rate,education,industrialization,and income inequality,institutional quality indicators such as governance effectiveness,control of corruption,freedom ad civil liberty,and democracy,and endogenous factors including fossil fuel energy use,fuelwood energy use,household health expenditure,infant mortality rate,and agriculture productivity influence the nexus between poverty and environmental degradation.The findings on the relationship between poverty and environmental degradation in SSA are a testimonial evidence that both poverty and environmental degradation are significant issues in SSA.Hence,poverty alleviation policies in SSA should not lead to PM2.5 emissions and deforestation,which may as well force people into a poverty-environmental degradation trap.Instead,poverty reduction policies should simultaneously achieve environmental conservation.

Nonlinear dynamical wave structures of Zoomeron equation for population models

The nonlinear dynamical exact wave solutions to the non-fractional order and the time-fractional order of the biological population models are achieved for the first time in the framwork of the Paul-Painlevéapproach method(PPAM).When the variables appearing in the exact solutions take specific values,the solitary wave solutions will be easily obtained.The realized results prove the efficiency of this technique.

Experimental Study on Enhanced Electrokinetic Remediation of Heavy Metal-contaminated Soil

In order to improve the efficiency of traditional electrokinetic remediation method of heavy metal-contaminated soil, cadmium-contaminated soil was remediated by two enhanced electrokinetic techniques, namely, the approaching anode method and intermittent current method. The remediation effect was verified under the conditions that the electric field strength was 2 V/cm, 0.1 mol/L citric acid was used as the electrolyte, and the remediation reaction time was 96 h. The results showed that for the approaching anode method, when the average electromigration distance was 5.48, the removal rate was 88.12%, which was 10.47% higher than the unenhanced technique, and the energy consumption per unit volume was 7.36 kWh/m^3;and as to the intermittent current method, the removal rate was 80.81%, and the energy consumption per unit volume was 8.12 kWh/m^3, which was relatively reduced by 33.07%. After the remediation, the proportions of the weak acid extractive form and reducible form of calcium decreased, and the proportions of the oxidizable form and residual form of cadmium did not change significantly.

Progress in satellite gravity recovery from implemented CHAMP,GRACE and GOCE and future GRACE Follow-On missions

Firstly, the Earth＇s gravitational field from the past Challenging Minisatellite Payload （CHAMP） mission is determined using the energy conservation principle, the combined error model of the cumulative geoid height influenced by three instrument errors from the current Gravity Recovery and Climate Experiment （GRACE） and future GRACE Follow-On missions is established based on the semi-analytical method, and the Earth＇s gravitational field from the executed Gravity Field and Steady-State Ocean Circulation Explorer （GOCE） mission is recovered by the space-time-wise approach. Secondly, the cumulative geoid height errors are 1.727 × 10^-1 m, 1.839 × 10^-1 m and 9.025 × 10^ -2 m at degrees 70,120 and 250 from the implemented three-stage satellite gravity missions consisting of CHAMP, GRACE and GOCE, which preferably accord with those from the existing earth gravity field models involving EIGEN-CHAMP03S, EICEN-GRACE02S and GO_CONS GCF 2 DIR R1. The cumulative geoid height error is 6.847 × 10 ^-2 m at degree 250 from the future GRACE Follow-On mission. Finally, the complementarity among the four-stage satellite gravity missions including CHAMP, GRACE, GOCE and GRACE Follow-On is demonstrated contrastively.

Seismic ground motion variations resulting from site conditions

Amplification of seismic ground motions in the territory of Almaty city is evaluated by using different methods. The pattern and probable causes of ground motion variations in different engineering-geological conditions are characterized. An expeditious application of these techniques within a complex methodical approach for Almaty city microzonation is considered.

Numerical Solution of Fractional Differential Equations

In this article, two numerical techniques, namely, the homotopy perturbation and the matrix approach methods have been proposed and implemented to obtain an approximate solution of the linear fractional differential equation. To test the effectiveness of these methods, two numerical examples with known exact solution are illustrated. Numerical experiments show that the accuracy of these methods is in a good agreement with the exact solution. However, a comparison between these methods shows that the matrix approach method provides more accurate results.

Multi-scale Modeling of the Ionic Diffusivity of Cement-based Materials

A new multiscale numerical approach was presented to predict the ionic diffusivity of cement based materials,which incorporated the lattice Boltzmann method,the conjugate gradient method,and the random walk method.In particular,the lattice Boltzmann method was applied to model the ionic diffusion in pore space of cement paste,while the upscaling of effective ionic diffusivity from cement paste（mortar） to concrete was processed by means of the conjugate gradient method and the random walk method.A case study was then presented,i e,the chloride diffusivity of concrete affected by sand content and gravel content.It is shown that the results of numerical prediction agree well with those of experimental measurements adopted from literatures.The multiscale numerical approach provides a prior assessment of ionic diffusivity for cement based materials from a microstructural basis.

A PERSONAL UNDERSTANDING OF SOME MAIN TEACHING APPROACHES AND METHODS IN FOREIGN LANGUAGE TEACHING

IntroductionAs theories of language and psychology have developed,new teaching approaches and methods haveemerged to accompany them.The appearance of these approaches and methods has not only met theneeds of contemporary language teaching,but also aroused the interest of the second and foreign languageteachers.Though there have been many controversies among applied linguists and teachers,uniquecharacteristics of each method can be identified.Some methods have been adopted universally.others areconfined to limited areas.Whatever the situation may be.a general review of these approaches andmethods is necessary,in order to get some insights into their nature,strengths and weaknesses.The resultwill hopefully be more effective language teaching.

BENEFITING FROM BOTH THE COMMUNICATIVE APPROACHES AND THE TRADITIONAL CHINESE METHODS IN ELT

For some time,ELT in China has been undergoing a heated discussion as to the best way ofteaching.Some think that the communicative approaches is inappropriate while others think that the tra-ditional Chinese methods are too old-fashioned.From various points of view,this paper argues that boththe communicative approach and the traditional Chinese methods can co-exist and influence each other inthe present Chinese teaching context.

A 3D hybrid grid generation technique and a multigrid/parallel algorithm based on anisotropic agglomeration approach

A hybrid grid generation technique and a multigrid/parallel algorithm are presented in this paper for turbulence flow simulations over three-dimensional （3D） complex geometries. The hybrid grid generation technique is based on an agglomeration method of anisotropic tetrahedrons. Firstly, the complex computational domain is covered by pure tetrahedral grids, in which anisotropic tetrahedrons are adopted to discrete the boundary layer and isotropic tetrahedrons in the outer field. Then, the anisotropic tetrahedrons in the boundary layer are agglomerated to generate prismatic grids. The agglomeration method can improve the grid quality in boundary layer and reduce the grid quantity to enhance the numerical accuracy and efficiency. In order to accelerate the convergence history, a multigrid/parallel algorithm is developed also based on anisotropic agglomeration approach. The numerical results demonstrate the excellent accelerating capability of this multigrid method.

Linking discrete particle simulation to continuum process modelling for granular matter: Theory and application

Two approaches are widely used to describe particle systems： the continuum approach at macroscopic scale and the discrete approach at particle scale. Each has its own advantages and disadvantages in the modelling of particle systems. It is of paramount significance to develop a theory to overcome the disadvantages of the two approaches. Averaging method to link the discrete to continuum approach is a potential technique to develop such a theory. This paper introduces an averaging method, including the theory and its application to the particle flow in a hopper and the particle-fluid flow in an ironmaking blast furnace.