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1 – 10 of 122Hong Tang and Xian-Xia Li
– The purpose of this paper is to discuss the light scattering of nonspherical particles that is very important for the research on the aerosol optical properties.
Abstract
Purpose
The purpose of this paper is to discuss the light scattering of nonspherical particles that is very important for the research on the aerosol optical properties.
Design/methodology/approach
In this paper, the authors use the spheroid model as the characteristic particle shape to study the single scattering albedo of real nonspherical particles. Meanwhile, the extinction and scattering cross section of spheroids are calculated with the T matrix method combined with the improved geometric optics approximation method (IGOM).
Findings
Through this combination, the extinction and scattering cross section of spheroids can be obtained in the larger size range and aspect ratio range. Furthermore, the comparison of the single scattering albedo for the spheroids and their equivalent spheres is conducted in order to investigate the difference of the spherical and nonspherical particles.
Originality/value
Simulation experiments indicate that the single scattering albedo of spheroids can be calculated well with this combination, and it has some obvious influence on the variation of the aspect ratio, incident wavelength, and complex refractive index of spheroid particles.
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Markus Kraiger and Bernhard Schnizer
The purpose of this paper is to present new expressions in Cartesian coordinates for the potential and magnetic field of prolate and oblate spheroids with arbitrary direction of…
Abstract
Purpose
The purpose of this paper is to present new expressions in Cartesian coordinates for the potential and magnetic field of prolate and oblate spheroids with arbitrary direction of the symmetry axis in a homogeneous field.
Design/methodology/approach
The potentials found in prolate or oblate spheroidal coordinates are transformed to Cartesian coordinates. These results are represented in such a form that they depend only on expressions, which are invariant under rotations around the symmetry axis. Thus, it is easy to change to arbitrary directions of both the symmetry axis and of that of the primary field. The gradients of the potentials are calculated and transformed exactly to the simplest form possible.
Findings
The paper presents simple expressions for the magnetic perturbations due to homogeneous prolate or oblate spheroids in a homogeneous magnetic field.
Research limitations/implications
Results are exact for single non‐ferromagnetic spheroids in a homogeneous field.
Practical implications
Superposition of these perturbations presupposes small values of the magnetic susceptibilities of both the spheroids and their environment as in biological tissues.
Originality/value
The paper presents novel formulas for fields of homogeneous spheroids in a homogeneous magnetic field which are very useful for modelling biological tissues in studies of magnetic resonance imaging and magnetic resonance spectroscopy.
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Building on the Rayleigh‐Stevenson approach fictitious internal source distributions responsible for the leading near‐field contribution of the long wavelength scattering by a…
Abstract
Building on the Rayleigh‐Stevenson approach fictitious internal source distributions responsible for the leading near‐field contribution of the long wavelength scattering by a non‐dissipative dielectric prolate spheroid are derived. The equivalent multiline sources arising from every polarization of the incoming field on the segment between the foci can be regarded as the result of an ultimate contraction of the volume polarization in the spheroid, or plainly as prolonged multipoles. In the low‐frequency asymptotic solution of the first‐order in terms of ω the solutions involve line and strip currents, and biline and quadriline charges, the density distributions of which obey simple polynomial laws. Numerical examples are provided, demonstrating their significance in the calculation of near‐zone fields in comparison with the direct radiation of elementary sets of point sources approximating the multiline distributions. The range of validity of the low‐frequency expansion is estimated by comparing with results obtained using the T‐matrix method.
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Rotational‐translational addition theorems for the vector spheroidal wave functions Ma(i)mn(h; ξ, η, φ) and Na(i)mn(h; ξ, η, φ), i = 1,2,3,4, are derived from those for the…
Abstract
Rotational‐translational addition theorems for the vector spheroidal wave functions Ma(i)mn(h; ξ, η, φ) and Na(i)mn(h; ξ, η, φ), i = 1,2,3,4, are derived from those for the corresponding scalar spheroidal wave functions ψ(i)mn(h; ξ, η, φ). A vector spheroidal wave function defined in one spheroidal coordinate system (h; ξ, η, φ) is expressed in terms of a series of vector spheroidal wave functions defined in another spheroidal coordinate system (h′; ξ′, η′, φ′), which is rotated and translated with respect to the first one. These theorems allow a rigorous treatment of boundary value problems relative to time‐harmonic vector field waves in the presence of a system of spheroids with arbitrary orientations. As a special case, general rotational‐translational addition theorems for vector spherical wave functions are also presented.
Stefan Prüger, Ashutosh Gandhi and Daniel Balzani
The purpose of this study is to quantify the impact of the variation of microstructural features on macroscopic and microscopic fields. The application of multi-scale methods in…
Abstract
Purpose
The purpose of this study is to quantify the impact of the variation of microstructural features on macroscopic and microscopic fields. The application of multi-scale methods in the context of constitutive modeling of microheterogeneous materials requires the choice of a representative volume element (RVE) of the considered microstructure, which may be based on some idealized assumptions and/or on experimental observations. In any case, a realistic microstructure within the RVE is either computationally too expensive or not fully accessible by experimental measurement techniques, which introduces some uncertainty regarding the microstructural features.
Design/methodology/approach
In this paper, a systematical variation of microstructural parameters controlling the morphology of an RVE with an idealized microstructure is conducted and the impact on macroscopic quantities of interest as well as microstructural fields and their statistics is investigated. The study is carried out under macroscopically homogeneous deformation states using the direct micro-macro scale transition approach.
Findings
The variation of microstructural parameters, such as inclusion volume fraction, aspect ratio and orientation of the inclusion with respect to the overall loading, influences the macroscopic behavior, especially the micromechanical fields significantly.
Originality/value
The systematic assessment of the impact of microstructural parameters on both macroscopic quantities and statistics of the micromechanical fields allows for a quantitative comparison of different microstructure morphologies and a reliable identification of microstructural parameters that promote failure initialization in microheterogeneous materials.
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G. Miano, G. Rubinacci and A. Tamburrino
The paper is focused on the numerical modelling of the interaction between electromagnetic fields and metallic nanoparticle.
Abstract
Purpose
The paper is focused on the numerical modelling of the interaction between electromagnetic fields and metallic nanoparticle.
Design/methodology/approach
A full‐wave solution of the field problem is modelled in terms of an integral equation where the unknown is the displacement current. For treating nanoparticles having sizes smaller than the relevant wavelength, particular care is devoted to the choice of the discrete representation of the unknown in view of the condition number of the resulting linear system of equations.
Findings
A critical analysis of the issues to be considered for developing a proper numerical model of the problem is presented. Specifically, it is shown that the electric field inside the nanoparticle is not purely irrotational, as usually assumed in the widespread models based on the electrostatic approximation.
Originality/value
The proposed formulation is applied for the first time to the problem of evaluating the interaction between electromagnetic fields and metallic nanoparticle.
Details
Keywords
That attack knocked 5.7 million b/d offline. Prince Abdelaziz bin Salman, the new energy minister, suggested that the entire Abqaiq output would be restored by the end of…
Details
DOI: 10.1108/OXAN-DB246709
ISSN: 2633-304X
Keywords
Geographic
Topical
Discusses the meaning of the term new world order (NWO) and defines its economic dimensions. Identifies three common principles of any workable NWO: material, social and spiritual…
Abstract
Discusses the meaning of the term new world order (NWO) and defines its economic dimensions. Identifies three common principles of any workable NWO: material, social and spiritual dimensions. Links these dimensions in an analytical framework. Reviews the literature on the theories and concepts which further our understanding and identification of societal ideals. Describes ways to integrate the social and spiritual dimensions into production, consumption and exchange. Attempts to link the ideals of a NWO with the potential behaviour of corporations to create a smoother transition towards sustained global welfare.
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Abstract
TWO nickel‐bearing commercial steels were oxidised in the range 1100°–1250°C for up to 8 hr. in air and CO2. The increase in thickness of the scale and the inner layer with embedded metal particles was followed in detail. A distinction is made between filaments which retain continuity with the base metal and discrete particles. The continuous filaments may be of practical importance in holding the scale to the metal in hot rolling, leading to surface defects on hot‐rolled products.
Owing to their relatively high alloy content, Ni‐Resist austenitic irons exhibit a higher degree of corrosion/erosion resistance than ordinary cast irons or cast carbon steels in…
Abstract
Owing to their relatively high alloy content, Ni‐Resist austenitic irons exhibit a higher degree of corrosion/erosion resistance than ordinary cast irons or cast carbon steels in all environments. The influence of the nickel alloying addition increases the “nobility” of Ni‐Resist, placing it in the galvanic table between the nickel‐free ferrous metals and copper‐base alloys such as gunmetal and aluminium bronze. Ni‐Resist irons vary in alloy content, to meet specific requirements, and are produced with both flake‐graphite and spheroid‐graphite structures. Practical experience indicates that in most applications the corrosion resistance of an SG Ni‐Resist iron is similar or superior to the corresponding flake‐graphite grade.