scholarly journals Random packing fraction of bimodal spheres: An analytical expression

2013 ◽  
Vol 87 (3) ◽  
Author(s):  
H. J. H. Brouwers
Keyword(s):  
Packing Fraction ◽  
Random Packing ◽  
Analytical Expression

Discrete Models for Particle Packings

1992 ◽  
Vol 278 ◽  
Author(s):  
A. Jagota ◽  
E.I. Dupont
Keyword(s):  
Particle Motion ◽  
Computational Models ◽  
Effective Conductivity ◽  
Packing Fraction ◽  
Random Packing ◽  
Simultaneous Equations ◽  
Discrete Models ◽  
Particle Center ◽  
Net Flux ◽  
Particle Packings

AbstractDiscrete computational models for the viscosities, sintering rates, and transport properties of sintering particle packings are presented. The packing is represented by a set of nodes (the particle centroids) connected by links (inter-particle contacts). The models for the mechanical behavior enforce equilibrium for each particle which leads to a set of simultaneous equations for the particle motion. Electrical or thermal transport through inter-particle contacts is modelled by imposing zero net flux at a node which also leads to a set of simultaneous equations for the value of potential at each particle center. The model is used to simulate the compaction of spheres to generate a threedimensional random packing. Statistical properties of the computed packing such as packing fraction, percolation threshold, and coordination number are compared with those of an experimental random packing. Results are also presented for the effective conductivity of mixtures of particles with very different conductivities.

On the influence of specimen thickness in TEM images of super-conducting vortices

1996 ◽  
Vol 54 ◽  
pp. 724-725
Author(s):  
J. Bonevich ◽  
D. Capacci ◽  
G. Pozzi ◽  
K. Harada ◽  
H. Kasai ◽  
...  
Keyword(s):  
Flux Line ◽  
Analytical Form ◽  
Realistic Model ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Flux Tubes ◽  
Analytical Expression ◽  
Flux Lines ◽  
Normal Core ◽  
Two Parameters

The successful observation of superconducting flux lines (fluxons) in thin specimens both in conventional and high Tc superconductors by means of Lorentz and electron holography methods has presented several problems concerning the interpretation of the experimental results. The first approach has been to model the fluxon as a bundle of flux tubes perpendicular to the specimen surface (for which the electron optical phase shift has been found in analytical form) with a magnetic flux distribution given by the London model, which corresponds to a flux line having an infinitely small normal core. In addition to being described by an analytical expression, this model has the advantage that a single parameter, the London penetration depth, completely characterizes the superconducting fluxon. The obtained results have shown that the most relevant features of the experimental data are well interpreted by this model. However, Clem has proposed another more realistic model for the fluxon core that removes the unphysical limitation of the infinitely small normal core and has the advantage of being described by an analytical expression depending on two parameters (the coherence length and the London depth).

Contrast From Point Defects in The Infinitesimal Approximation

1980 ◽  
Vol 38 ◽  
pp. 350-351
Author(s):  
L. J. Sykes ◽  
J. J. Hren
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Broad Class ◽  
Stacking Fault ◽  
Crystalline Solids ◽  
Dislocation Loops ◽  
Analytical Expression ◽  
Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

FACTOR OF QUALITY FOR PASSIVE NON-TUNABLE BAND-STOP FILTERS

2019 ◽  
pp. 71-74
Author(s):  
N. I. Unru ◽  
E. I. Ashcherbagin
Keyword(s):  
Quality Criterion ◽  
Physical Structure ◽  
Electrical Characteristics ◽  
Central Frequency ◽  
Analytical Expression ◽  
Notch Band ◽  
Attenuation Level ◽  
Calculation Results ◽  
Design And Manufacture

The notion of a quality criterion for non-tunable band-stop filters is introduced, and on the basis of it a comparison of filters with different designs is performed. The quality criterion takes into account the electrical characteristics of the filter and its dimensions, including the volume, the central frequency of the notch band, the level of total losses in the passbands, the width of the notch band by the level of total losses, the width of the notch band by attenuation level. Thus, it allows you to compare the quality of design and manufacture of passive notch filters of various types. The necessary analytical expression is presented, and for a number of variants of filter execution, the corresponding calculation results are given. The stated materials allow us to estimate and optimize the system of interrelated parameters of filters of an arbitrary physical structure.

scholarly journals A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy

2021 ◽  
Author(s):  
Davide Campanella ◽  
Gianluca Buffa ◽  
Ernesto Lo Valvo ◽  
Livan Fratini
Keyword(s):  
Room Temperature ◽  
Incremental Forming ◽  
Material Model ◽  
Numerical Approach ◽  
Forming Limit ◽  
Material Strength ◽  
Wall Angle ◽  
Analytical Expression ◽  
The Poor ◽  
Specific Material

AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a range of 25–400 °C and wall angle in a range of 35–60°. An analytical expression of the fracture forming limit, as a function of temperature, was established and finally tested with a different geometry in order to assess the validity.

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