Impurity Dispersion Research Articles

Research on Shape-Controllable Localized Heating Method Driven by Digital Microfluidics.

The localized heating technique, which minimizes high-temperature impact on thermally sensitive components and reduces impurity dispersion during encapsulation, has become a focal point in MEMS packaging research. In this study, we propose a method for localized heating at specific positions and shapes. A localized heating device, based on distributed electric field control, is constructed, where a polymer droplet on the lower substrate electrode is driven into a liquid column under the influence of a distributed electric field generated between two parallel substrate electrodes. ITO substrate electrodes with various patterns are fabricated, ensuring the shape of the formed liquid column matches the pattern. Leveraging the principles of heat transfer, the temperature of the polymer droplet is regulated via a heating stage to enable targeted heating of defined shapes and areas. Experiments delve into the impact of driving parameters on heating time and efficiency, with results affirming the proposed method's capability to govern localized heating for particular regions and configurations accurately.

Mathematical and computer modeling of atmospheric air pollutants transformation with input data refinement

<p>This article addresses the critical issue of harmful impurity dispersion in industrial facility atmospheres, considering point sources and factoring in photochemical changes. Conjugate equations are employed to assimilate pollutant data into the transfer equations' right side. Boundary conditions derive from global models like weather research and forecasting (WRF) and system for integrated modeling of atmospheric composition (SILAM), customized for the unique characteristics of an industrial city's pollutants. To encompass anthropogenic heat sources and surface heterogeneity, the model incorporates differential schemes for the atmospheric boundary layer, transport equations, and impurity transformation equations. Parameters for photochemical transformations, varying with weather and time of day, are derived from Ust-Kamenogorsk. A cloud-based geoinformation system (GIS) is developed for monitoring and forecasting air pollution. It assimilates data sources and accounts for photochemical transformations, enabling visualization of diverse weather and environmental scenarios. The article presents numerical modeling results of impurity spread and transformation influenced by mesometeorological processes, topography, and water resources within a specific city.</p>

Industrial emissions effect into atmospheric air quality: mathematical modeling.

This paper presents the results of modeling the distribution process of industrial emission components at specified distances from the emission source along the normal. The model uses a system of differential diffusion equations to compute the concentration profiles of aerosols, industrial gases, and fine particles in the atmosphere. In order to investigate the regularity of the emitter propagation into the atmosphere, a theory of impurity dispersion was developed. The model is constrained by the effect of particle interactions. The partial derivative equations are presented to calculate the concentrations of aerosols and fine particles under the turbulent airflow in the atmosphere, dispersion of inert impurities, and distribution of chemically active compounds. The adequacy of the mathematical model for a series of theoretical calculations was checked by contrasting the data of the atmospheric air monitoring for the cities of Almaty, Ust-Kamenogorsk, Pavlodar, Atyrau, Krasnodar, Chelyabinsk, Beijing, and Shanghai. Air monitoring data included PM10, SO2, and NO2 levels. The mathematical model solutions for the relative values of the emitter concentration in the direction along the normal of the pollution source at the surface were obtained. Graphical interpretation of the calculation results over the 0…200m distance for time intervals ranging from 3 to 600min was provided. According to the multiple factor cluster analysis, the critical values of SO2 concentrations in Atyrau exceeded MPC in 26.2% of cases. The level of NO2 for Shanghai was 15.6%, and those for PM10 concentrations in Almaty and Atyrau amounted to 16.4%. A comparison of theoretical values and results obtained from official sources showed arithmetic mean of 49.4mg/m3 and maximum value of 823.0mg/m3. Standard deviation comprised 48.9mg/m3. Results were considered statistically significant at p≤0.005. The mathematical model developed in this study can be used to predict the status of atmospheric air.

The mathematical description of the bulk fluid flow and that of the content impurity dispersion, obtained by replacing integer order temporal derivatives with general temporal Caputo or general temporal Riemann-Liouville fractional order derivatives, are objective

In the field of fractional calculus applications, there is a tendency to admit that “integer-order derivatives cannot simply be replaced by fractional-order derivatives to develop fractional-order theories”. There are different arguments for that: initialization problem, inconsistency, use of nonsingular or singular kernels, loss of objectivity. In this paper it is shown that the mathematical description of the bulk fluid flow and that of the content impurity spread replacing integer order temporal derivatives with general temporal Caputo or general temporal Riemann-Liouville fractional order derivatives, are objective. More precisely, it is proven that, the mathematical description of the bulk fluid 2D flow and that of the content impurity spread, in a horizontal unconfined aquifer, obtained replacing integer order temporal derivatives with general temporal Caputo or general temporal Riemann-Liouville fractional order derivatives, are objective. It is also proven that, the mathematical description of a Newtonian, incompressible, viscous bulk fluid 3D flow and that of the contained impurity dispersion, obtained replacing integer order temporal derivatives with general temporal Caputo or general temporal Riemann-Liouville fractional order derivatives, are objective. The obtained results show the compatibility of the general temporal Caputo and general temporal Riemann-Liouville fractional order derivatives with the understanding of the “measured time” evolution. In the same time these results reveal that, the objectivity violation, when integer order temporal derivatives are replaced by classic temporal Caputo or classic temporal Riemann-Liouville fractional order derivatives, is originated in the incompatibility of the classic fractional order derivatives, with the understanding of the “measured time” evolution.

Mathematical description of the bulk fluid flow and that of the contained impurity dispersion which uses Caputo or Riemann-Liouville fractional order partial derivatives is nonobjective

In this paper it is shown that the mathematical description of a Newtonian, incompressible, viscous bulk fluid flow and that of the contained impurity dispersion which uses Caputo or Riemann-Liouville fractional order derivative, having integral representation on finite interval, is nonobjective. This means that, two different observers describing the flow or the contained impurity dispersion with these tools obtain two different results which cannot be reconciled i.e. transformed into each other using only formulas that link the coordinates of a point in two fixed orthogonal reference frames and formulas that link the numbers representing a moment of time in two different choices of the origin of time measuring. This is not an academic curiosity! It is rather a problem: which of the obtained results is correct?

Mobile impurity approach to the optical conductivity in the Hubbard chain

We consider the optical conductivity in the one dimensional Hubbard model in the metallic phase close to half filling. In this regime most of the spectral weight is located at frequencies above an energy scale $E_{\rm opt}$ that tends towards the optical gap in the Mott insulating phase for vanishing doping. Using the Bethe Ansatz we relate $E_{\rm opt}$ to thresholds of particular kinds of excitations in the Hubbard model. We then employ a mobile impurity models to analyze the optical conductivity for frequencies slightly above these thresholds. This entails generalizing mobile impurity models to excited states that are not highest weight with regards to the SU(2) symmetries of the Hubbard chain, and that occur at a maximum of the impurity dispersion.

Mobile magnetic impurities in a Fermi superfluid: a route to designer molecules.

A magnetic impurity in a fermionic superfluid hosts bound quasiparticle states known as Yu-Shiba-Rusinov states. We argue here that, if the impurity is mobile (i.e., has a finite mass), the impurity and its bound Yu-Shiba-Rusinov quasiparticle move together as a midgap molecule, which has an unusual "Mexican-hat" dispersion that is tunable via the fermion density. We map out the impurity dispersion, which consists of an "atomic" branch (in which the impurity is dressed by quasiparticle pairs) and a "molecular" branch (in which the impurity binds a quasiparticle). We discuss the experimental realization and detection of midgap Shiba molecules, focusing on Li-Cs mixtures, and comment on the prospects they offer for realizing exotic many-body states.

Modeling of impurity cloud propagation under the action of wind in the ground layer

A qualitative analysis and numerical modeling of two- and three-dimensional problems on stationary propagation of a gas impurity under the action of the wind are carried out. It is shown that vertical turbulent diffusion is a major channel of impurity dispersion. A comparison with the data of proving-ground tests confirmed this conclusion. An analytical expression is obtained for the characteristic length of impurity scattering that amounts to about 10–15 m, and it is shown that this length is independent of the wind velocity and is determined by the properties of the underlying soil surface.

Field experiment on studying solar radiation passing through aerosol layers

Results of a field experiment on studying solar radiation passing in the visible wavelength range are described with the model aerosol media created in the surface atmosphere. High-efficiency thermocondensation generators were used for creating model aerosol media. The index of refraction and an average size of the aerosol particles formed are close to those characteristic of the natural stratospheric aerosol. The composition and technical characteristics of the equipment complex used in the experiments to control aerosol optical and microphysical parameters and meteorological conditions of the experiment are considered. The Gaussian model of impurity dispersion in the boundary layer is used for the analysis and interpretation of measurement results. It is found that with a number concentration of aerosol particles of ∼102–103 cm−3 (which corresponds to the aerosol density in the deposited layer of about 1–10 mg/m2 with the layer thickness along the ray path of about 100 m) the solar radiation attenuation with artificial aerosol layers accounts for 1 to 10%. Model estimates are in satisfactory agreement with the measurement results.

Impurity dispersion in nonuniform flows

Impurity dispersion in nonuniform flows

Impurity dispersion in circular tube

In describing various mass-transfer processes, wide use has been made of a diffusional model with an effective diffusion (dispersion) coefficient. The basic theory of dispersion was developed in [i, 2], where an equation with constant coefficients for the mean (over the cross section) particle concentration was proposed, together with a complex diffusion equation with a transfer rate depending on the coordinate transverse to the flow. Taylor calculated the dispersion coefficient and performed an experiment confirming the adequacy of the model. Subsequently, the dispersion theory was intensively developed, and several basic approaches to the derivation of the equivalent-diffusion equation and its generalization may be distinguished [3-5]. Here the dispersion equation is obtained by the smallperturbation method [6, 7], using Taylor considerations regarding the order of magnitude of terms in the initial diffusion equation. First, the impurity-dispersion equation is found with a weak dependence of the flow velocity on the impurity concentration. Then the problem is formulated for the first correction to the solution of the Taylor dispersion equation in the case of a parabolic profile of the flow velocity in the circular tube. Next, the analysis of the limiting solution of a characteristic nonsteady problem of impurity transfer around the wall of a prismatic channel of sufficiently general form is briefly considered.

Effect of secondary eddy flows on impurity dispersion in a zonal current: Eremeev, V.N., L.M. Ivanov, I.A. Neelov and V.I. Smelyansky, 1986. Fiz. Atmosf. Okeana, 22(1):78–86. (In Russian, English abstract.)

Effect of secondary eddy flows on impurity dispersion in a zonal current: Eremeev, V.N., L.M. Ivanov, I.A. Neelov and V.I. Smelyansky, 1986. Fiz. Atmosf. Okeana, 22(1):78–86. (In Russian, English abstract.)

Mobilité dans PbTe de type n au-dessous de 50 K

n type lead telluride mobility is calculated at low temperatures, taking into account phonon dispersion. Ionized impurity dispersion is calculated with a screened Coulomb potential plus a short range one. The results of an iterative calculation of the mobility show that is not possible to rule out acoustical dispersion, whose importance is comparable with that on ionized impurities. Comparison with experimental results in cases where compensation is negligible indicates that the short range part of the potential in ionized impurity scattering must not be taken into account. In other situations, experimental results are described fairly well by a realistic compensation Evaluation theorique en incluant la dispersion sur les phonons, la dispersion sur les impuretes etant traitee a l'aide d'un potentiel coulombien avec ecran et d'un potentiel a courte distance: l'importance de la dispersion sur les phonons acoustiques est comparable a celle sur les impuretes ionisees

The role of impurity dispersion and hardness anisotropy studies in NaCl:Sm crystals

AbstractThe effect of the distributed impurities and their state of dispersion on hardness of crystal is studied from microhardness measurements on NaCl crystals doped with different concentrations of samarium both in as‐grown state as well as after quenching them from various elevated temperatures. It is found that the small additions of impurity decrease the hardness. This has been explained on the basis of formation and dissolution of precipitates

Impurity dispersion in the turner model for flow in a porous channel

A one-dimensional model for longitudinal diffusion in a capillary with an immobile layer is derived.