Small Solid Particles Research Articles

Spherical and cylindrical shocks in a non-ideal dusty gas with magnetic field under the action of heat conduction and radiation heat flux

In this article, the propagation of spherical or cylindrical shock waves in a mixture of small solid particles of microsize and a non-ideal gas with conductive as well as radiative heat fluxes are studied under the influence of an azimuthal or axial magnetic field. The solid particles are uniformly distributed in the mixture, and the shock wave is assumed to be driven by a piston. It is assumed that the equilibrium flow conditions are maintained and the moving piston continuously supplies the variable energy input. The density of the undisturbed medium is assumed to be constant in order to obtain the self-similar solutions. Heat conduction is expressed in terms of Fourier’s law, and the radiation is considered to be of diffusion type for an optically thick gray gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density. Numerical calculations have been performed to obtain the flow profiles of variables. The effects of different values of the non-idealness parameter, the strength of the magnetic field, the mass concentration, the ratio of the density of solid particles to the initial density of the gas, the piston velocity index, and the adiabatic index are shown in detail. It is interesting to note that in the presence of an azimuthal magnetic field, the pressure and density vanish at the piston, and hence, a vacuum is formed at the center of symmetry, which is in excellent agreement with the laboratory condition to produce the shock wave. The author of the article agrees to the retraction of the article effective AUGUST 20, 2021.

Solution of the Riemann problem for an ideal polytropic dusty gas in magnetogasdynamics

Abstract The main aim of this paper is, to obtain the analytical solution of the Riemann problem for a quasi-linear system of equations, which describe the one-dimensional unsteady flow of an ideal polytropic dusty gas in magnetogasdynamics without any restriction on the initial data. By using the Rankine-Hugoniot (R-H) and Lax conditions, the explicit expressions of elementary wave solutions (i. e., shock waves, simple waves and contact discontinuities) are derived. In the flow field, the velocity and density distributions for the compressive and rarefaction waves are discussed and shown graphically. It is also shown how the presence of small solid particles and magnetic field affect the velocity and density across the elementary waves. It is an interesting fact about this study that the results obtained for the Riemann problem are in closed form.

Assessment of Air Quality in the South-Western Part of the Świętokrzyskie Mountains Based on Selected Indicators

This article presents the results of research on the air quality which was under the anthropogenic impact of the cement and lime industry in the Świętokrzyskie Mountains for many years. Research using geo- and bio-indicators was carried out at fixed measuring points in the years 2016–2018. Hypogymnia physodes (L.) Nyl. and two-year old Scots pine needles Pinus sylvestris L. were used for bioindication research. Physico-chemical properties of precipitation were developed on the basis of research conducted at the Jan Kochanowski University’s field research station located on the Malik Mt. Increased pH and specific electrolytic conductivity (EC) of precipitation, as well as variable concentrations of heavy metals throughout a year were found. Analysis of the chemical properties of transplanted lichens and pine needles confirmed the presence of elements from the cement and lime industry sector located in the Białe Zagłębie. Scanning electron microscope (SEM) image of the needles’ surface revealed morphologic changes resulting from pollution of stoma opening and closing by small solid particles of anthropogenic origins, disturbing gas exchange.

Capillary rise in a closed column: Application to the characterization of powders

We present analytical solutions to the capillary rise of a wetting liquid in a closed column packed with small solid particles, including hydrostatic effects and the non-linear dependence of the pressure differential on the penetration height of the liquid. The solutions describe the evolution of both the penetration height (and mass) of the liquid and the pressure differential that develops in the closed column. Using closed column systems provides versatility to characterize different liquid-solid systems, covering a broad range of capillary pressures, by directly, and independently measuring both liquid mass and pressure differential. We identify the two non-dimensional parameters governing the evolution of the system, that is the capillary pressure and the initial pressure in the closed column, both made non-dimensional with the effective column height of the system. These results provide the means to improve and possibly optimize the experimental setup and conditions for any given liquid-solid system under consideration. For example, we show how modifying the effective column height and the initial pressure in the closed column could significantly reduce the duration of capillary rise experiments.

On the evolution of finite and small amplitude waves in non-ideal gas with dust particles

The present work concerns with the study of progressive wave solution for the waves of finite and moderately small amplitude in the mixture of the non-ideal gas and dust particles governed by quasilinear hyperbolic system of PDEs. Using the progressive wave method, we derive the transport equation which provides the conditions of the shock formation, and equation to determine the shock strength. Also, it is shown that how the presence of the parameter of non-idealness and mass fraction of dust particles influence the shock formation and shock strength for the planar and non planar cases. We also discuss the consequence of variation in the value of the non-ideal parameter and the mass fraction of small solid dust particles on the evolutionary process of the shock.

Effect of solid dust particles on the propagation of shock wave in planar and non-planar gasdynamics

The aim of the present study is to analyze the propagation of shock wave along the characteristic path in planar and non-planar unsteady compressible ideal gas flow in presence of small solid dust particles. The analytical solution of the governing quasilinear hyperbolic system is computed in the characteristic plane and it is found that this analytical linear solution in this plane can exhibit non-linear phenomenon in the physical plane. The effect of the dust particles on the evolutionary behavior of the propagating shock wave in ideal gas flow is discussed. The transport equations leading to the evolution of shock wave is determined which introduces the conditions of shock formation. The growth and decay of compressive waves and expansive waves, respectively, in planar and non-planar ideal gas dynamics influenced by the presence of small solid dust particles, is discussed.

An Efficient Analytical Solution of Blast Wave Problem in Real Gas Flow under the Influence of Dust Laden Particles

In the present paper, we investigated the problem of the propagation of blast waves governed by a nonhomogeneous quasilinear hyperbolic system of partial differential equations (PDEs), describing one-dimensional unsteady motion with generalized geometries in a real gas flow (van der Waals gas) in which the influence of the dust particles is significant. An efficient analytical approach has been used to the governing hyperbolic system with respect to the Rankine-Hugoniot (RH) conditions to obtain an exact solution in terms of flow parameters density, velocity and the pressure, which exhibits space-time dependence. Further, an analytical expression for the total energy influenced by real gas effects (consisting of non-ideal gas and small solid dust-laden particles) is derived. The results obtained significantly explore the effect of dust-laden particles on the propagation of blast waves in a van der Waals gas.

An experimental study of turbulent vortex rings in superfluid 4He

Macroscopic vortex rings are generated thermally in superfluid 4He, between 1.28 and 1.95 K, by applying a brief voltage pulse to a resistive heater located below a circular vertical tube 5 mm in diameter and 20 mm high. The rings form above the tube and propagate upward with velocities of the order of , resulting in Reynolds numbers up to . We visualize their cross-section, of size comparable with the tube diameter, by capturing the motions of relatively small solid deuterium particles, previously dispersed in the quiescent bath of superfluid 4He. We employ particle positions and velocities to compute the Lagrangian pseudovorticity, which can be seen as a measure of the ring strength and which allows us to identify and track these objects. We thus obtain time-dependent sizes, positions and velocities of the vortex rings. We show that, in the range of investigated parameters, these rings behave as if they were turbulent vortex rings moving in classical viscous fluids, at least in the direction of ring propagation. The outcome reinforces the view that the study of turbulent flows of superfluid 4He is not only interesting in its own right, but that it can also contribute to our current understanding of fluid turbulence in general.

Cathode Chemistries and Electrode Parameters Affecting the Fast Charging Performance of Li-Ion Batteries

Abstract Li-ion battery fast-charging technology plays an important role in popularizing electric vehicles (EV), which critically need a charging process that is as simple and quick as pumping fuel for conventional internal combustion engine vehicles. To ensure stable and safe fast charging of Li-ion battery, understanding the electrochemical and thermal behaviors of battery electrodes under high rate charges is crucial, since it provides insight into the limiting factors that restrict the battery from acquiring energy at high rates. In this work, charging simulations are performed on Li-ion batteries that use the LiCoO2 (LCO), LiMn2O4 (LMO), and LiFePO4 (LFP) as the cathodes. An electrochemical-thermal coupling model is first developed and experimentally validated on a 2.6Ah LCO based Li-ion battery and is then adjusted to study the LMO and LFP based batteries. LCO, LMO, and LFP based Li-ion batteries exhibited different thermal responses during charges due to their different entropy profiles, and results show that the entropy change of the LCO battery plays a positive role in alleviating its temperature rise during charges. Among the batteries, the LFP battery is difficult to be charged at high rates due to the charge transfer limitation caused by the low electrical conductivity of the LFP cathode, which, however, can be improved through doping or adding conductive additives. A parametric study is also performed by considering different electrode thicknesses and secondary particle sizes. It reveals that the concentration polarization at the electrode and particle levels can be weaken by using thin electrodes and small solid particles, respectively. These changes are helpful to mitigate the diffusion limitation and improve the performance of Li-ion batteries during high rate charges, but careful consideration should be taken when applying these changes since they can reduce the energy density of the batteries.

Morphometric Analysis of Paramylon Particles Produced by Euglena gracilis EOD-1 Using FIB/SEM Tomography.

Euglena gracilis EOD-1, a microalgal strain, produces large quantities of paramylon, a class of polymers known as β-1,3-glucans and has been reported to function as a dietary fiber and to improve the metabolic syndrome including obesity. However, despite its importance, the morphometric analysis of paramylon has not been conducted so far. In this study, we attempted to observe the detailed three-dimensional structure of paramylon by focused ion beam/scanning electron microscopy (FIB/SEM). Paramylon samples were fixed and three-dimensional image reconstruction and segmentation of the image stack were created using computer software (Amira v6.0.1, FEI). The results indicated that the inside of paramylon particles (diameter: 5 µm, thickness: 3 µm) was comprised of a dense structure with no evidence of the presence of large pores and gaps, although a small 100 nm crack was observed. The specific surface area of paramylon particles measured by the Brunauer-Emmet-Teller (BET) method, was not as large as activated charcoal, but similar to those of plant starches, indicating that the cholesterol-lowering effect of paramylon cannot be simply attributed to its adsorption ability. The FIB/SEM method was found to be useful for elucidating the internal structure of small solid particles.

CLASSIFICATION OF HIGH AND LOW LEVEL OF PM10 CONCENTRATIONS IN KLANG AND SHAH ALAM, MALAYSIA

Particulate matter (PM) comprises of a complex mixture of small solid or liquid particles of organic and inorganic elements that floats freely in air. PM10 is defined as a particulate matter with an aerodynamic diameter of 10 m or less. The main objective of this paper is to classify the level of PM10 in selected locations in Peninsular Malaysia using discriminant analysis. Two important components considered in this study, namely; the meteorological factors and pollutant factors. The meteorological factors comprise of wind speed, wind direction, humidity and temperature while pollutant factors consist of Carbon Monoxide (CO), Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2) and Ozone (O3). The classification of high or low level of PM10 concentrations was based on the Malaysia Ambient Air Quality Guideline (MAAQG). The findings indicated that the classification equation differs from location to location due to different levels of PM10 concentrations, location of monitoring stations and factors affecting air pollution in that location. The simulation data also verified that the classification of PM10 concentration was almost similar to the real condition that occurred in Klang in October 2015.

Rapid Expansion Supercritical Solution (RESS) of Carbon Dioxide as a Green Technology Method for Leucaena Leucocephala Solid Oil Particle Formation

Rapid expansion supercritical solution (RESS) is a technology introduced that produces a small solid oil particle with organic solvent free particle. RESS method is a better method compared to the traditional method due to many advantages such are produce clean extraction yields, obtain free solvent traces, environmental friendly and short processing time can be used in various industries such as cosmetic and pharmaceutical. Therefore, RESS technique is applied in order to produce direct solid oil particle from Luecaena leucocephala (L.leucocephala) pods instead of oil. In this study, the operating condition that applied during the RESS process in order to obtain the highest solid oil particle from the L.leucocephala pods sample are extraction temperature of 40 ºC, 45 ºC, 50 ºC, 55 ºC and 60 ºC and extraction pressure of 3000 psi, 4000 psi, 5000 psi, 6000 psi and 7000 psi at the constant extraction time of 40 minutes. The highest yield of L.leucocephala solid oil particles that obtained is about 0.65% at 60 oC and 7000 psi. The major components that obtained from the highest yield are 2,2,3-trimethyldecane, Cyclopentanone, propanoic acid and Cyclobutane, 1,2-diphenyl- by as identified by using Gas Chromatography Mass Spectrometry (GCMS).

Multiple nature analysis of Carreau nanomaterial flow due to shrinking geometry with heat transfer

An astonishing feature of modern research in the field of fluid flow and heat transfer is the suspension of small solid particles (nanoparticle) in the working fluid to increase the low thermal conductivity of these fluids. Because of unique chemical and physical properties, nanomaterials are being progressively utilized in almost every field of science and technology. Therefore, the intent of current manuscript is to theoretically examine the magneto-hydrodynamic flow of Carreau nanofluids along with heat transport in the presence of heat generation driven by a wedge-shaped shrinking geometry. We incorporated the revised Buongiorno’s model in which nanofluids particle fraction on the boundary is passively controlled. Mathematical modeling of assumed physical problem results in a system of non-linear partial differential equations outlining the basic conservation laws. The governing problem is made dimensionless with the assistance of non-dimensional variables and numerical solutions are computed via a built-in MATLAB solver bvp4c. The computed results showed that multiple solutions (first and second) exist for the non-dimensional velocity, temperature and concentration distributions by applying the said numerical scheme. We concluded that by enhancing the magnetic parameter the nanofluid velocity increases in case of second solution while an opposite is true for temperature. Further, the outcomes indicate that higher heat generation parameter leads to enhance the temperature distributions in both solutions.

Dichlorination in a circulating fluidized-bed incinerator for municipal solid waste incineration system

Cl is one of the main pollutants emitted from domestic waste incineration systems. In this study, we focused on the process of Ca dechlorination in the furnace of a circulating fluidized-bed waste incineration system. We analyzed the stability of CaCl2 and Ca in the furnace, the dechlorination process, and distribution of Cl in the incineration system. The results show that the optimal Ca/Cl molar ratio for Ca dechlorination in the circulating fluidized-bed waste incinerator is 2:1; moreover, the dechlorination product CaCl2 was found to decompose at high temperatures (> 850 °C). At temperatures > 700 °C, we measured CaCl2 decomposition rates up to 80%. Ca was added in the furnace, mainly to provide a dechlorination Ca source for the decomposition of limestone into tail flue gas. The amount of Ca2+ in the flue decreased gradually, parallelly to the temperature of the flue gas. Stable CaCl2 was formed after HCl was captured, and relatively small solid particles appeared in the ash collecting bag.

Modelling of sprays: simple solutions of complex problems

Some new approaches to the solution of complex problems, focused on spray modelling, using relatively simple mathematical tools are briefly summarised. The following problems are considered: modelling of spray drying with pharmaceutical applications, modelling of heating and evaporation of suspended droplets with applications to water sprays for fire suppression, modelling of micro-explosions with automotive applications, and parameterisations of slow invariant manifolds with applications to spray ignition modelling. The modelling of spray drying is based on the assumption that the array of small suspended solid particles inside droplets can be treated as a non-evaporating liquid component. The modelling of the effect of a support rod on droplet heating and evaporation is based on the assumption that this heat is homogeneously distributed inside the whole volume of a droplet. In the modelling of a puffing/micro-explosion it is assumed that a water sub-droplet is located exactly at the centre of a fuel droplet and the temperature at the surface of the fuel droplet is fixed. In the presentation of slow invariant manifolds in parametric form these manifolds are found using asymptotic expansions.

Impact of PM2.5 on Second Birth Intentions of China's Floating Population in a Low Fertility Context.

The total fertility rate of the Chinese population has declined dramatically over the last three decades. Research has substantiated the causal link between particulate matter (PM) and adverse health effects. However, the impact of PM on the birth intentions or fertility behavior of the childbearing population remains understudied. The paper analyzes the impact of PM2.5 concentration (a mixture of extremely small solid particles and liquid droplets found in the air) on the second birth intentions of the Chinese floating population. We used urban migrant population matching data at the prefectural level for the analysis. The unique datasets were derived from the Chinese Floating Population Dynamic Survey in 2014 administered by the National Health Commission, the National Prefecture-level City Matching Data administered by the National Bureau of Statistics of China, and the air pollution index PM2.5 collected by the Green Peace Organization. The results show that PM2.5 concentration has a negative impact on the second birth intentions of the floating population. This impact exhibits marked regional heterogeneity: the desire for a second birth across migrant groups living in south China decreases if PM2.5 concentration goes up, while migrants coming from, and living in, north China show strong intentions to have a second birth despite an increase in PM2.5 concentration in northern cities. The results have direct implications for the Chinese government at various levels to play a vital role in making and implementing environmental policies on the mitigation of smog to effectively safeguard the health of individuals and communities and potentially raise China’s fertility rate.

Indoor Dust Exposure Detection System For Air Purifier Controller Based Arduino And LabVIEW

Dust is a very small solid particle (generally in units of micron) carried by air so it can be breathed anywhere either outdoors or indoors. According to the decision of kepala badan pengendalian dampak lingkungan number: Kep-107/Kabapedal/11/1997, dust exposure is one of the indicators of air pollution affecting the quality of life and public health. Therefore, a system capable of detecting and controlling the level of dust exposure is required. In this study a dust-proof detection was designed using the GP2Y1010AUOF sensor as a dust or particulate matter (PM10) and DS18B20 sensor which is a digital temperature sensor to monitor room temperature. As a simulation of air neutralization used mini car home dual use usb humidifier water-drop air purifier aroma diffus, Arduino Uno as Master Control Unit (MCU) which functions to manage data sensor readings into digital data and to display the level of exposure of dust and air temperature of the room is used LCD character 16x2. A graphical and numerical display of data is displayed on a computer or laptop using graphical user interface LabVIEW.

The Riemann problem for one-dimensional isentropic flow of a mixture of a non-ideal gas with small solid particles

We concern with the Riemann problem for one-dimensional inviscid and isentropic flow of a mixture of a non-ideal gas with small solid particles. The expressions of elementary wave curves are established. Besides, we reveal the properties of these wave curves. Furthermore, all kinds of solution patterns to the Riemann problem are shown. Finally, the comparisons between semi-analytical results and numerical results to the Riemann problem are carried out, which are in good agreement with the corresponding theoretical analysis.

Diffusive Motion in a 3-D Cluster in PK-4

Random motion of small solid particles is analyzed in a 3-D dusty plasma experiment under microgravity conditions. In this experiment, performed using the Plasmakristall-4 (PK-4) instrument on board the international space station, a cloud of microspheres was localized near a radio frequency coil that powered a neon plasma. We devised a method of correcting particle mean-square displacement (MSD) data to account for a small hydrodynamic flow. Using a time series of the MSD, we determined that random motion was nearly diffusive, with a diffusion coefficient of 0.0017 mm2/s. Another measure of displacements, the probability distribution function, fits a Kappa distribution with $\kappa = 6.9$ , indicating that the random motion was nearly Gaussian.

Propagation of strong cylindrical shock wave in a self-gravitating rotational axisymmetric mixture of small solid particles and perfect gas with density varying exponentially

The non-similarity solution for the propagation of a strong cylindrical shock wave in a self-gravitating and rotational axisymmetric dusty gas, having variable azimuthal and axial fluid velocities is obtained. The dusty gas is assumed to be a mixture of small solid particles of micro size and perfect gas. The equilibrium flow conditions are assumed to be maintained. The density of the mixture and the fluid velocities in the ambient medium are assumed to be varying and obeying an exponential law. The shock wave moves with variable velocity and the total energy of the wave is non-constant. The effects of variation of the mass concentration of solid particles in the mixture, the ratio of the density of solid particles to the initial density of the gas, and the gravitational parameter on the flow variables in the region behind the shock are investigated at a given time in both the rotating and non-rotating cases. Our analysis reveals that an increase in gravitational parameter or in the ratio of the density of solid particles to the initial density of the gas surprisingly the shock strength increases and remarkable differences are found in the distribution of flow variables in both the rotating and non-rotating cases. An increase in time also, increases the shock strength in the case of isothermal flow, but to decrease the shock strength in the case of adiabatic flow in general. Further, it is investigated that the consideration of isothermal flow increases the shock strength. A comparison is made between the solutions in isothermal and adiabatic flow cases with or without gravitational effects in both the rotating and non-rotating medium. The obtained solutions are applicable for arbitrary values of time.