scholarly journals Critical spin periods of sub-km-sized cohesive rubble-pile asteroids: dependencies on material parameters

2021 ◽  
Author(s):  
Shoucun Hu ◽  
Derek C Richardson ◽  
Yun Zhang ◽  
Jianghui Ji
Keyword(s):  
Continuum Theory ◽  
Friction Angle ◽  
Dynamical Process ◽  
Remarkable Difference ◽  
Soft Sphere ◽  
Material Parameters ◽  
Different Diameters ◽  
Best Fit ◽  
Rubble Pile ◽  
The Continuum

Abstract In this work, we employed a soft-sphere discrete element method with a cohesion implementation to model the dynamical process of sub-km-sized cohesive rubble piles under continuous spinup. The dependencies of the critical spin periods Tc on several material parameters for oblate rubble piles with different diameters were explored. Our simulations show that the interparticle cohesive force can strengthen the bodies as expected, especially for the smaller ones. The simulated results of Tc were fitted with the continuum theory developed by Holsapple (2007), through which we find the interparticle cohesion is proportional to the best-fit bulk cohesion and the ratio shows no dependency on the density. In addition, we find Tc decreases as the density increases in the compressive regime, while the trend reverses when transitioning to the tensile regime. Besides, though a higher friction angle can strengthen the bodies, its influence on Tc is minimized near the separation between the two regimes. Our numerical findings are generally consistent with the continuum theory, except that the latter predicts that Tc should increase as the friction angle increases in the tensile regime, which is contrary to the numerical results. This remarkable difference reminds us to take caution when applying the continuum theory to critically spinning cohesive rubble piles in the tensile regime, especially when dealing with the effect of the friction angle. Finally, we emphasize that the separation between the regimes can be specified by a characteristic period, which is only a function of density for a given shape.

Confirming the continuum theory of dynamic brittle fracture for fast cracks

Nature ◽  
10.1038/16891 ◽  
1999 ◽  
Vol 397 (6717) ◽  
pp. 333-335 ◽  
Author(s):  
Eran Sharon ◽  
Jay Fineberg
Keyword(s):  
Brittle Fracture ◽  
Continuum Theory ◽  
Dynamic Brittle Fracture ◽  
The Continuum

scholarly journals Matrix integrals & finite holography

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Dionysios Anninos ◽  
Beatrix Mühlmann
Keyword(s):  
Critical Exponents ◽  
Continuum Theory ◽  
Point Of View ◽  
Leading Order ◽  
Minimal Models ◽  
Point Evaluation ◽  
Brst Cohomology ◽  
Matrix Integrals ◽  
The Matrix ◽  
The Continuum

Abstract We explore the conjectured duality between a class of large N matrix integrals, known as multicritical matrix integrals (MMI), and the series (2m − 1, 2) of non-unitary minimal models on a fluctuating background. We match the critical exponents of the leading order planar expansion of MMI, to those of the continuum theory on an S2 topology. From the MMI perspective this is done both through a multi-vertex diagrammatic expansion, thereby revealing novel combinatorial expressions, as well as through a systematic saddle point evaluation of the matrix integral as a function of its parameters. From the continuum point of view the corresponding critical exponents are obtained upon computing the partition function in the presence of a given conformal primary. Further to this, we elaborate on a Hilbert space of the continuum theory, and the putative finiteness thereof, on both an S2 and a T2 topology using BRST cohomology considerations. Matrix integrals support this finiteness.

On the Motion of Granular Materials Due to Shear

2000 ◽  
Author(s):  
Mehrdad Massoudi ◽  
Tran X. Phuoc
Keyword(s):  
Finite Difference ◽  
Granular Materials ◽  
Continuum Model ◽  
Theory Model ◽  
Governing Equations ◽  
Flat Plates ◽  
Material Parameters ◽  
Finite Difference Technique ◽  
Linear Differential ◽  
The Continuum

Abstract In this paper we study the flow of granular materials between two horisontal flat plates where the top plate is moving with a constant speed. The constitutive relation used for the stress is based on the continuum model proposed by Rajagopal and Massoudi (1990), where the material parameters are derived using the kinetic theory model proposed by Boyle and Massoudi (1990). The governing equations are non-dimensionalized and the resulting system of non-linear differential equations is solved numerically using finite difference technique.

On the Properties of Gelatin-Dye Phosphors and the Continuum Theory of Szent-Gyorgyi

Science ◽  
1948 ◽  
Vol 107 (2787) ◽  
pp. 566-567
Author(s):  
Michael Kasha
Keyword(s):  
Continuum Theory ◽  
The Continuum

Ferronematics: On the development of the continuum theory approach

1990 ◽  
Vol 85 (1-3) ◽  
pp. 74-76 ◽  
Author(s):  
S.V. Burylov ◽  
Yu.L. Raikher
Keyword(s):  
Continuum Theory ◽  
Theory Approach ◽  
The Continuum

Free Energy of Granular Materials in Static Equilibrium

1979 ◽  
Vol 46 (4) ◽  
pp. 944-945 ◽  
Author(s):  
M. Shahinpoor ◽  
G. Ahmadi
Keyword(s):  
Free Energy ◽  
Granular Materials ◽  
Continuum Theory ◽  
Gravitational Effect ◽  
Experimental Results ◽  
Static Equilibrium ◽  
The Continuum

We employ the continuum theory of granular materials due to Goodman and Cowin and some experimental results due to P. G. Nutting to arrive at a functional from for the free energy of granular materials in static equilibrium. The results obtained indicate the dominance of gravitational effect, modify and enlarge the results previously obtained by J. T. Jenkins.

Dislocation Threading Through an Epitaxial Film: an Analysis Based on the Peierls-Nabarro Concept

1993 ◽  
Vol 308 ◽  
Author(s):  
G. E. Beltz ◽  
L. B. Freund
Keyword(s):  
Critical Thickness ◽  
Epitaxial Film ◽  
Continuum Theory ◽  
Dislocation Core ◽  
Critical Layer Thickness ◽  
Cutoff Parameter ◽  
Mismatch Strain ◽  
Realistic Description ◽  
Cutoff Radius ◽  
The Continuum

ABSTRACTThe Peierls-Nabarro theory of crystal dislocations is applied to estimate the critical thickness of a strained layer bonded to a substrate for a given mismatch strain. Previous analyses were based on the continuum theory of elastic dislocations, and hence depended on the artificial core cutoff parameter r0. The Peierls-Nabarro theory makes use of an interplanar shear law, which leads to a more realistic description of the stresses and displacements in the vicinity of a dislocation core, thus eliminating the need for the core cutoff parameter. The dependence of the critical layer thickness on the mismatch strain in films with a diamond cubic lattice is found to be similar to that predicted by the continuum elastic dislocation theory, provided that a core cutoff radius equal to about one-tenth the Burgers displacement is used.

scholarly journals Contributions to the theory of the specific heat of crystals I—Lattice theory and continuum theory

1935 ◽  
Vol 148 (864) ◽  
pp. 365-383 ◽  
Keyword(s):  
Specific Heat ◽  
Empirical Formula ◽  
Lattice Theory ◽  
Continuum Theory ◽  
Quantum Statistics ◽  
Physical Basis ◽  
General Explanation ◽  
The Continuum

The variation of the specific heat of crystals with temperature received a satisfactory general explanation as soon as quantum statistics were applied to the motion of the particles of which a crystal is composed. The first formula on such a basis, proposed by Einstein, gave fairly satisfactory results, but showed large discrepancies at the lowest temperatures; an empirical formula due to Nernst and Lindemann gave better agreement but lacked a satisfactory physical basis. Two consistent theories were advanced practically simultaneously by Debye and Born and v. Kármán. Debye's theory is based on the ingenious idea of replacing a crystal by a continuum as far as the distribution of the vibrations is concerned, cutting off the spectrum at a suitable point. Because of its inherent simplicity and because it can be applied to non-crystals as well as to crystals, the continuum theory has taken precedence and now is practically the only one which received attention.

scholarly journals Edge modes of gravity. Part II. Corner metric and Lorentz charges

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Laurent Freidel ◽  
Marc Geiller ◽  
Daniele Pranzetti
Keyword(s):  
Phase Space ◽  
Lorentz Invariance ◽  
Discrete Series ◽  
Continuum Theory ◽  
Symmetry Algebra ◽  
Area Spectrum ◽  
Area Element ◽  
Bf Theory ◽  
Tetrad Gravity ◽  
The Continuum

Abstract In this second paper of the series we continue to spell out a new program for quantum gravity, grounded in the notion of corner symmetry algebra and its representations. Here we focus on tetrad gravity and its corner symplectic potential. We start by performing a detailed decomposition of the various geometrical quantities appearing in BF theory and tetrad gravity. This provides a new decomposition of the symplectic potential of BF theory and the simplicity constraints. We then show that the dynamical variables of the tetrad gravity corner phase space are the internal normal to the spacetime foliation, which is conjugated to the boost generator, and the corner coframe field. This allows us to derive several key results. First, we construct the corner Lorentz charges. In addition to sphere diffeomorphisms, common to all formulations of gravity, these charges add a local $$ \mathfrak{sl} $$ sl (2, ℂ) component to the corner symmetry algebra of tetrad gravity. Second, we also reveal that the corner metric satisfies a local $$ \mathfrak{sl} $$ sl (2, ℝ) algebra, whose Casimir corresponds to the corner area element. Due to the space-like nature of the corner metric, this Casimir belongs to the unitary discrete series, and its spectrum is therefore quantized. This result, which reconciles discreteness of the area spectrum with Lorentz invariance, is proven in the continuum and without resorting to a bulk connection. Third, we show that the corner phase space explains why the simplicity constraints become non-commutative on the corner. This fact requires a reconciliation between the bulk and corner symplectic structures, already in the classical continuum theory. Understanding this leads inevitably to the introduction of edge modes.

Continuum-Wise Expansive Homeomorphisms

1993 ◽  
Vol 45 (3) ◽  
pp. 576-598 ◽  
Author(s):  
Hisao Kato
Keyword(s):  
Continuum Theory ◽  
Topological Dynamics ◽  
Expansive Homeomorphism ◽  
The One ◽  
Chainable Continua ◽  
The Continuum

AbstractThe notion of expansive homeomorphism is important in topological dynamics and continuum theory. In this paper, a new kind of homeomorphism will be introduced and studied, namely the continuum-wise expansive homeomorphism. The class of continuum-wise expansive homeomorphisms is much larger than the one of expansive homeomorphisms. In fact, the class of continuum-wise expansive homeomorphisms contains many important homeomorphisms which often appear in "chaotic" topological dynamics and continuum theory, but which are not expansive homeomorphisms. For example, the shift maps of Knaster's indecomposable chainable continua are continuum-wise expansive homeomorphisms, but they are not expansive homeomorphisms. Also, there is a continuum-wise expansive homeomorphism on the pseudoarc. We study several properties of continuum-wise expansive homeomorphisms. Many theorems concerning expansive homeomorphisms will be generalized to the case of continuum-wise expansive homeomorphisms.

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