Pattern and Process in Ecological Systems: A Step in the Development of a General Ecological Theory

1994 ◽  
Vol 51 (1) ◽  
pp. 226-246 ◽  
Author(s):  
Lionel Johnson
Keyword(s):  
Free Energy ◽  
Energy Flow ◽  
Arctic Lakes ◽  
Hierarchical Level ◽  
Least Action ◽  
Principle Of Least Action ◽  
Induce Change ◽  
Point Of Intersection ◽  
Physical Principles

The dominant fish populations in undisturbed arctic lakes are characterized as being in a state of "least specific dissipation": the greatest biomass attainable for a given energy input. A survey of autonomous ecosystems in various parts of the world indicated that this pattern is widespread. It is concluded that ecosystems are formed at the point of intersection of two established physical principles: the "principle of most action" (≈least dissipation or conservation of free energy) and the "principle of least action". "Action" is defined as the product of energy times time (joule-seconds). The trend to "most action" necessitates deceleration of energy flow: "least action" accelerates energy flow. For an ecosystem to survive over ecological time, the principle of most action must override the principle of least action. In that different species of organism have different capacities to conserve free energy (increase action), a hierarchy is formed locally in which action increases at each hierarchical level. Over the long term, as a result of genetic instability, both principles induce change, but the principle of least action dominates system behaviour causing increasingly rapid energy dissipation. Evolution is the resultant of these two countervailing forces.

scholarly journals Bayesian mechanics of perceptual inference and motor control in the brain

2021 ◽  
Author(s):  
Chang Sub Kim
Keyword(s):  
Free Energy ◽  
Prediction Errors ◽  
Environmental Niche ◽  
Perceptual Inference ◽  
Numerical Illustration ◽  
Energy Principle ◽  
Agent Based ◽  
Least Action ◽  
Principle Of Least Action ◽  
The Brain

AbstractThe free energy principle (FEP) in the neurosciences stipulates that all viable agents induce and minimize informational free energy in the brain to fit their environmental niche. In this study, we continue our effort to make the FEP a more physically principled formalism by implementing free energy minimization based on the principle of least action. We build a Bayesian mechanics (BM) by casting the formulation reported in the earlier publication (Kim in Neural Comput 30:2616–2659, 2018, 10.1162/neco_a_01115) to considering active inference beyond passive perception. The BM is a neural implementation of variational Bayes under the FEP in continuous time. The resulting BM is provided as an effective Hamilton’s equation of motion and subject to the control signal arising from the brain’s prediction errors at the proprioceptive level. To demonstrate the utility of our approach, we adopt a simple agent-based model and present a concrete numerical illustration of the brain performing recognition dynamics by integrating BM in neural phase space. Furthermore, we recapitulate the major theoretical architectures in the FEP by comparing our approach with the common state-space formulations.

On the Shoulders of Giants

2018 ◽  
Author(s):  
David D. Nolte
Keyword(s):  
Eighteenth Century ◽  
Robert Hooke ◽  
New Approach ◽  
Isaac Newton ◽  
Least Action ◽  
New Science ◽  
Principle Of Least Action ◽  
Parabolic Trajectory ◽  
Leonhard Euler ◽  
New Generation

Galileo’s parabolic trajectory launched a new approach to physics that was taken up by a new generation of scientists like Isaac Newton, Robert Hooke and Edmund Halley. The English Newtonian tradition was adopted by ambitious French iconoclasts who championed Newton over their own Descartes. Chief among these was Pierre Maupertuis, whose principle of least action was developed by Leonhard Euler and Joseph Lagrange into a rigorous new science of dynamics. Along the way, Maupertuis became embroiled in a famous dispute that entangled the King of Prussia as well as the volatile Voltaire who was mourning the death of his mistress Emilie du Chatelet, the lone female French physicist of the eighteenth century.

scholarly journals Microstructure Evolution in a Solid Oxide Fuel Cell Stack Quantified with Interfacial Free Energy

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3476
Author(s):  
Tomasz A. Prokop ◽  
Grzegorz Brus ◽  
Janusz S. Szmyd
Keyword(s):  
Free Energy ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Microstructure Evolution ◽  
Ion Beam ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Long Term Performance ◽  
Term Performance

Degradation of electrode microstructure is one of the key factors affecting long term performance of Solid Oxide Fuel Cell systems. Evolution of a multiphase system can be described quantitatively by the change in its interfacial energy. In this paper, we discuss free energy of a microstructure to showcase the anisotropy of its evolution during a long-term performance experiment involving an SOFC stack. Ginzburg Landau type functional is used to compute the free energy, using diffuse phase distributions based on Focused Ion Beam Scanning Electron Microscopy images of samples taken from nine different sites within the stack. It is shown that the rate of microstructure evolution differs depending on the position within the stack, similar to phase anisotropy. However, the computed spatial relation does not correlate with the observed distribution of temperature.

scholarly journals Nonlinear vibrations and time delay control of an extensible slowly rotating beam

2020 ◽  
Author(s):  
Jerzy Warminski ◽  
Lukasz Kloda ◽  
Jaroslaw Latalski ◽  
Andrzej Mitura ◽  
Marcin Kowalczuk
Keyword(s):  
Time Delay ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Least Action ◽  
Active Elements ◽  
Principle Of Least Action ◽  
Second Mode ◽  
Delay Control ◽  
Speed Range ◽  
System With Time Delay

AbstractNonlinear dynamics of a rotating flexible slender beam with embedded active elements is studied in the paper. Mathematical model of the structure considers possible moderate oscillations thus the motion is governed by the extended Euler–Bernoulli model that incorporates a nonlinear curvature and coupled transversal–longitudinal deformations. The Hamilton’s principle of least action is applied to derive a system of nonlinear coupled partial differential equations (PDEs) of motion. The embedded active elements are used to control or reduce beam oscillations for various dynamical conditions and rotational speed range. The control inputs generated by active elements are represented in boundary conditions as non-homogenous terms. Classical linear proportional (P) control and nonlinear cubic (C) control as well as mixed ($$P-C$$ P - C ) control strategies with time delay are analyzed for vibration reduction. Dynamics of the complete system with time delay is determined analytically solving directly the PDEs by the multiple timescale method. Natural and forced vibrations around the first and the second mode resonances demonstrating hardening and softening phenomena are studied. An impact of time delay linear and nonlinear control methods on vibration reduction for different angular speeds is presented.

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 Ice processes and growth history on Arctic and sub-Arctic lakes using ERS-1 SAR data

Polar Record ◽  
1995 ◽  
Vol 31 (177) ◽  
pp. 115-128 ◽  
Author(s):  
K. Morris ◽  
M. O. Jeffries ◽  
W. F. Weeks
Keyword(s):  
Arctic Lakes ◽  
Polar Regions ◽  
Lake Ice ◽  
Sar Images ◽  
The North ◽  
Growth History ◽  
North Slope Of Alaska ◽  
Term Monitoring ◽  
Selection Of

AbstractA survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period of ice cover (September to June) for the years 1991–92 and 1992–93. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

Application of principle of least action to beam problems

2000 ◽  
Vol 142 (1-4) ◽  
pp. 235-243 ◽  
Author(s):  
B. Tabarrok ◽  
W. L. Cleghorn
Keyword(s):  
Least Action ◽  
Principle Of Least Action

scholarly journals Evaluation of Functioning Quality of Local Electrical Systems by the Criterion Method Based on Markov Processes

2019 ◽  
pp. 169-172 ◽  
Author(s):  
Petro Lezhniuk ◽  
Vyacheslav Komar ◽  
Natalya Sobchuk ◽  
Olena Sikorska
Keyword(s):  
Markov Processes ◽  
Renewable Energy Sources ◽  
Network Development ◽  
Least Action ◽  
Electrical Systems ◽  
Principle Of Least Action ◽  
Intensive Development ◽  
Criterion Method ◽  
The Ideal

The article proposes to use of a combination of the criterion method and Markov processes to evaluate the quality of functioning of renewable energy sources (RES) in the form of integrated readiness characteristic of the electricity network with RES or a local electrical system (LES). This is possible throughthe analysis of the problems of ensuring the quality of electricity supply in the conditions of intensive development of RES and defined by the qualimetric characteristics of the electricity networks, which are important for the provision of quality electricity. This contribute the development of generalizedsolutions and network development strategies, especially when it comes to building RES. The components of the integral index are determined as the probability of matching the actual regime to the "ideal". The "ideal" mode is determined on the basis of the principle of least action and corresponds to the circuit diagram of the network formed by the r-scheme. The basis thus determined in this way reduces the subjectivity of both evaluations and decisions taken on the basis of it.

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