scholarly journals Cosmology from a new nonconservative gravity

2018 ◽  
Vol 27 (06) ◽  
pp. 1841006 ◽  
Author(s):  
Júlio C. Fabris ◽  
Hermano Velten ◽  
Thiago R. P. Caramês ◽  
Matheus J. Lazo ◽  
Gastão S. F. Frederico
Keyword(s):  
Fluid Model ◽  
Gravitational Theory ◽  
Dissipative Process ◽  
The Novel ◽  
Least Action Principle ◽  
Dynamical Equations ◽  
First Order ◽  
Least Action ◽  
Dissipative Effects ◽  
Cosmic Background

In this paper, we present a cosmological model arising from a nonconservative gravitational theory proposed in [M. J. Lazo, J. Paiva, J. T. S. Amaral and G. S. F. Frederico, Phys. Rev. D 95 (2017) 101501.] The novel feature where comparing with previous implementations of dissipative effects in gravity is the possible arising of such phenomena from a least action principle, so they are of a purely geometric nature. We derive the dynamical equations describing the behavior of the cosmic background, considering a single fluid model composed by pressureles matter, whereas the dark energy is conceived as an outcome of the “geometric” dissipative process emerging in the model. Besides, adopting the synchronous gauge, we obtain the first-order perturbative equations which shall describe the evolution of the matter perturbations within the linear regime.

The Hamiltonian Field Theory of the Von Mises Wave Equation: Analytical and Computational Issues

2016 ◽  
Vol 19 (3) ◽  
pp. 758-769
Author(s):  
Christian Cherubini ◽  
Simonetta Filippi
Keyword(s):  
Field Theory ◽  
Wave Equation ◽  
Scalar Potential ◽  
Mathematical Structure ◽  
Least Action Principle ◽  
Dynamical Equations ◽  
Least Action ◽  
Functional Forms ◽  
Von Mises ◽  
Lagrangian Densities

AbstractThe Von Mises quasi-linear second order wave equation, which completely describes an irrotational, compressible and barotropic classical perfect fluid, can be derived from a nontrivial least action principle for the velocity scalar potential only, in contrast to existing analog formulations which are expressed in terms of coupled density and velocity fields. In this article, the classicalHamiltonian field theory specifically associated to such an equation is developed in the polytropic case and numerically verified in a simplified situation. The existence of such a mathematical structure suggests new theoretical schemes possibly useful for performing numerical integrations of fluid dynamical equations. Moreover it justifies possible new functional forms for Lagrangian densities and associated Hamiltonian functions in other theoretical classical physics contexts.

scholarly journals A least action principle for interceptive walking

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Soon Ho Kim ◽  
Jong Won Kim ◽  
Hyun Chae Chung ◽  
MooYoung Choi
Keyword(s):  
Social Systems ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Action Principle ◽  
Lagrange Equations ◽  
Least Action Principle ◽  
Least Action ◽  
The Least Action Principle ◽  
Principle Of Least Action ◽  
Human Participants

AbstractThe principle of least effort has been widely used to explain phenomena related to human behavior ranging from topics in language to those in social systems. It has precedence in the principle of least action from the Lagrangian formulation of classical mechanics. In this study, we present a model for interceptive human walking based on the least action principle. Taking inspiration from Lagrangian mechanics, a Lagrangian is defined as effort minus security, with two different specific mathematical forms. The resulting Euler–Lagrange equations are then solved to obtain the equations of motion. The model is validated using experimental data from a virtual reality crossing simulation with human participants. We thus conclude that the least action principle provides a useful tool in the study of interceptive walking.

scholarly journals Phase reconstruction by the weighted least action principle

2006 ◽  
Vol 8 (3) ◽  
pp. 279-289 ◽  
Author(s):  
Chungmin Lee ◽  
John Lowengrub ◽  
Jacob Rubinstein ◽  
Xiaoming Zheng
Keyword(s):  
Action Principle ◽  
Phase Reconstruction ◽  
Least Action Principle ◽  
Least Action

scholarly journals ON SUPERLUMINAL FERMIONS WITHIN THE SECOND DERIVATIVE EQUATION

2012 ◽  
Vol 27 (14) ◽  
pp. 1250081 ◽  
Author(s):  
S. I. KRUGLOV
Keyword(s):  
Energy Momentum Tensor ◽  
Canonical Quantization ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Order Equation ◽  
Quantum Mechanical ◽  
Projection Operators ◽  
The Novel ◽  
First Order ◽  
Electromagnetic Interactions

We postulate the second-order derivative equation with four parameters for spin-1/2 fermions possessing two mass states. For some choice of parameters fermions propagate with the superluminal speed. Thus, the novel tachyonic equation is suggested. The relativistic 20-component first-order wave equation is formulated and projection operators extracting states with definite energy and spin projections are obtained. The Lagrangian formulation of the first-order equation is presented and the electric current and energy–momentum tensor are found. The minimal and nonminimal electromagnetic interactions of fermions are considered and Schrödinger's form of the equation and the quantum-mechanical Hamiltonian are obtained. The canonical quantization of the field in the first-order formalism is performed and we find the vacuum expectation of chronological pairing of operators.

scholarly journals Nonlinear Dynamics of a Vibratory Cone Crusher with Hysteretic Force and Clearances

2011 ◽  
Vol 18 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Jing Jiang ◽  
Qing-Kai Han ◽  
Chao-Feng Li ◽  
Hong-Liang Yao ◽  
Shu-Ying Liu
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Deep Understanding ◽  
Degree Of Freedom ◽  
The Novel ◽  
Hysteretic Model ◽  
Dynamical Equations ◽  
Motion Patterns ◽  
Dynamical Behaviors ◽  
Cone Crusher ◽  
Two Degree Of Freedom

Based on the analysis on crushing process and hysteresis of material layers, a hysteretic model with symmetrical clearances is presented. The mechanical model of two-degree of freedom with bilinear hysteresis and its dynamical equations of system are proposed. In order to further investigate the dynamic characteristics of the novel vibratory cone crusher, the system is also simplified into a dynamical system of single degree of freedom with a bilinear hysteretic component together with clearances. According to some nonlinear dynamic analysis tools such as bifurcation diagram, Lyapunov exponents, Poincare section, etc., different motion patterns of the system are discussed, including periodic, periodic doubling, chaos and other characteristics. These theoretical results will provide readers with deep understanding on the regular and complex dynamical behaviors of the vibratory cone crusher due to the hysteresis with clearances.

Transient Response of Laminated Plates Subject to Close Proximity Explosions

1999 ◽  
Author(s):  
John M. Coggin ◽  
Jeffrey M. K. Chock ◽  
Rakesh K. Kapania ◽  
Eric R. Johnson
Keyword(s):  
Transient Response ◽  
Composite Plates ◽  
Laminated Plates ◽  
Blast Load ◽  
The Novel ◽  
Element Mesh ◽  
Simply Supported ◽  
First Order ◽  
Close Proximity ◽  
Load Types

Abstract We study the transient response of simply supported composite plates subject to close proximity explosions. Many studies are currently availiable in which the blast load is applied uniformly across the plate; and is described by step, N-pulse, or Friedlander equations. The novel aspect considered here is the case for which the blast pressure is due to a close proximity explosion, and is therefore taken to be both spatially and temporally varying. Two methods for calculating blast pressures are developed for arbitrary blast size and distance. A FORTAN program is described that automates the application of an arbitrary blast load to a generic finite element mesh. Modal superposition and NASTRAN solution procedures are verified for several load types and stacking sequences. Results are obtained within the framework of classical and first order plate theories for a variety of parameters including; stacking sequence, blast size, blast distance, and blast calculation method.

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