The Writer’s Secret: Natural Description and Its Narrative Logic in Silence

2020 ◽  
Vol 08 (02) ◽  
pp. 31-39
Author(s):  
莉 曹
Keyword(s):  
Natural Description

Variational Principles

2012 ◽  
Author(s):  
Joram Lindenstrauss ◽  
David Preiss ◽  
Tiˇser Jaroslav
Keyword(s):  
Variational Principle ◽  
Lower Semicontinuity ◽  
Variational Principles ◽  
Perfect Information ◽  
Perturbation Functions ◽  
Abstract Version ◽  
Recursive Constructions ◽  
Natural Description

This chapter describes smooth variational principles (of Ekeland type) as infinite two-player games. These variational principles are based on a simple but careful recursive choice of points where certain functions that change during the process have values close to their infima. Like many other recursive constructions, the choice has a natural description using the language of infinite two-player games with perfect information. The chapter first considers the perturbation game used in Theorem 7.2.1 to formulate an abstract version of the variational principle before showing how to specialize it to more standard formulations. It then examines the bimetric variant of the smooth variational principle, along with the perturbation functions that are relatively simple. It concludes with an assessment of cases when completeness and lower semicontinuity hold only in a bimetric sense.

Validation of an Improved Contact Method for Multi-Material Eulerian Hydrocodes in Three-Dimensions

2019 ◽  
Author(s):  
Kenneth C. Walls ◽  
David L. Littlefield
Keyword(s):  
Finite Element ◽  
Large Deformations ◽  
Three Dimensions ◽  
Contact Method ◽  
Arbitrary Lagrangian Eulerian ◽  
Aspect Ratios ◽  
Ale Methods ◽  
Lagrangian Finite Element ◽  
Multiple Materials ◽  
Natural Description

Abstract Realistic and accurate modeling of contact for problems involving large deformations and severe distortions presents a host of computational challenges. Due to their natural description of surfaces, Lagrangian finite element methods are traditionally used for problems involving sliding contact. However, problems such as those involving ballistic penetrations, blast-structure interactions, and vehicular crash dynamics, can result in elements developing large aspect ratios, twisting, or even inverting. For this reason, Eulerian, and by extension Arbitrary Lagrangian-Eulerian (ALE), methods have become popular. However, additional complexities arise when these methods permit multiple materials to occupy a single finite element.

Complete problems for fixed-point logics

1995 ◽  
Vol 60 (2) ◽  
pp. 517-527 ◽  
Author(s):  
Martin Grohe
Keyword(s):  
Fixed Point ◽  
Computational Complexity ◽  
Normal Form ◽  
Query Language ◽  
Main Step ◽  
Complexity Classes ◽  
Complete Problem ◽  
Complete Problems ◽  
Database Query Language ◽  
Natural Description

The notion of logical reducibilities is derived from the idea of interpretations between theories. It was used by Lovász and Gács [LG77] and Immerman [Imm87] to give complete problems for certain complexity classes and hence establish new connections between logical definability and computational complexity.However, the notion is also interesting in a purely logical context. For example, it is helpful to establish nonexpressibility results.We say that a class of τ-structures is a >complete problem for a logic under L-reductions if it is definable in [τ] and if every class definable in can be ”translated” into by L-formulae (cf. §4).We prove the following theorem:1.1. Theorem. There are complete problemsfor partial fixed-point logic andfor inductive fixed-point logic under quantifier-free reductions.The main step of the proof is to establish a new normal form for fixed-point formulae (which might be of some interest itself). To obtain this normal form we use theorems of Abiteboul and Vianu [AV91a] that show the equivalence between the fixed-point logics we consider and certain extensions of the database query language Datalog.In [Dah87] Dahlhaus gave a complete problem for least fixed-point logic. Since least fixed-point logic equals inductive fixed-point logic by a well-known result of Gurevich and Shelah [GS86], this already proves one part of our theorem.However, our class gives a natural description of the fixed-point process of an inductive fixed-point formula and hence sheds some light on completely different aspects of the logic than Dahlhaus's construction, which is strongly based on the features of least fixed-point formulae.

A natural description of aircraft motions

1996 ◽  
Author(s):  
Giulio Avanzini ◽  
Guido d ◽  
Luciano d
Keyword(s):  
Natural Description

THE DIFFEOMORPHISM GROUP APPROACH TO NONLINEAR QUANTUM SYSTEMS

1992 ◽  
Vol 06 (11n12) ◽  
pp. 1905-1916 ◽  
Author(s):  
GERALD A. GOLDIN
Keyword(s):  
Nonlinear Effects ◽  
Quantum Systems ◽  
Incompressible Fluids ◽  
Diffeomorphism Groups ◽  
Group Approach ◽  
Quantum Vortex ◽  
Nonlinear Quantum ◽  
New Applications ◽  
Fundamental Physical ◽  
Natural Description

Unitary representations of diffeomorphism groups predict some unusual possibilities in quantum theory, including non-standard statistics and certain nonlinear effects. Many of the fundamental physical properties of “anyons” were first derived from their study by R. Menikoff, D.H. Sharp, and the author. This paper surveys new applications in two other domains: first (with Menikoff and Sharp) some surprising conclusions about the nature of quantum vortex configurations in ideal, incompressible fluids; second (with H.-D. Doebner) a natural description of dissipative quantum mechanics by means of a nonlinear Schrödinger equation different from the sort usually studied. Our equation follows from including a diffusion current in the equation of continuity.

On Networks and Monsters: The Possible and the Actual in Complex Systems

Leonardo ◽  
2008 ◽  
Vol 41 (3) ◽  
pp. 253-258 ◽  
Author(s):  
Ricard Solé
Keyword(s):  
Complex Systems ◽  
Real World ◽  
Multiple Scales ◽  
Social Systems ◽  
Emergent Phenomena ◽  
Genome Dynamics ◽  
Natural Description

Complex systems pervade our real world, from social systems to genome dynamics. All these systems are characterized by the presence of emergent phenomena: New properties emerge from the interactions of simpler units and are not reducible to the properties of the latter. The natural description of complex systems involves a network view, where each system is represented by means of a web. Such graphs have been shown to share surprisingly universal patterns of organization, indicating that fundamental laws of organization also pervade complexity at multiple scales.

scholarly journals Initial Energy Density of √ s = 7 and 8 TeV p+p Collisions at the LHC

2016 ◽  
Author(s):  
Mate Csanad ◽  
Tamas Csorgo ◽  
Ze-Fang Jiang ◽  
Chun-Bin Yang
Keyword(s):  
Energy Density ◽  
Critical Energy ◽  
High Energy ◽  
Initial Energy ◽  
High Multiplicity ◽  
Initial Energy Density ◽  
Critical Energy Density ◽  
High Energy Collisions ◽  
8 Tev ◽  
Natural Description

Accelerating, exact, explicit and simple solutions of relativistic hydrodynamics allow for a simple and natural description of highly relativistic p+p collisions. These solutions yield a finite rapidity distribution, thus they lead to an advanced estimate of the initial energy density of high energy collisions. We show that such an advanced estimate yields an initial energy density in $\sqrt{s}=7$ and 8 TeV p+p collisions at LHC around or above the critical energy density from lattice QCD, and a corresponding initial temperature above the critical temperature from QCD and the Hagedorn temperature. This suggests that the collision energy of the LHC corresponds to a large enough initial energy density to create a non-hadronic perfect fluid even in pp collisions. %We also show, that several times the %critical energy density may have been reached in high multiplicity events, hinting at a non-hadronic medium created in %high multiplicity $\sqrt{s}=7$ and 8 TeV p+p collisions.

scholarly journals Natural Spring Cell Substitutes of Simplex Finite Elements

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Finite Elements ◽  
Elastic Anisotropy ◽  
Triangular Element ◽  
Cell Models ◽  
Plane Case ◽  
Tetrahedral Element ◽  
Flexibility Matrix ◽  
The Subject ◽  
Natural Spring ◽  
Natural Description

Spring cell models are presented which derive from the natural description of simplex finite elements, that is in conformity with the geometry of the triangle in the plane and of the tetrahedron in space. Thereby, the spring cells are interpreted as part of the finite elements. The deduction of two spring cells as defective substitutes is demonstrated for the triangular element. One approximates the flexibility matrix of the element, the other approximates the stiffness matrix. The performance with respect to the finite element is analyzed, the issue of elastic anisotropy is discussed. In space, the spring cell substitute of the tetrahedral element is derived from the flexibility matrix, an inherent difference to the plane case is pointed out. Remarks on the implication of plasticity are added. The account gives a brief summary of recent work on the subject.

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