9,133 research outputs found
A Variational Assimilation Method for Satellite and Conventional Data: a Revised Basic Model 2B
A variational objective analysis technique that modifies observations of temperature, height, and wind on the cyclone scale to satisfy the five 'primitive' model forecast equations is presented. This analysis method overcomes all of the problems that hindered previous versions, such as over-determination, time consistency, solution method, and constraint decoupling. A preliminary evaluation of the method shows that it converges rapidly, the divergent part of the wind is strongly coupled in the solution, fields of height and temperature are well-preserved, and derivative quantities such as vorticity and divergence are improved. Problem areas are systematic increases in the horizontal velocity components, and large magnitudes of the local tendencies of the horizontal velocity components. The preliminary evaluation makes note of these problems but detailed evaluations required to determine the origin of these problems await future research
A Variational Assimilation Method for Satellite and Conventional Data: Model 2 (version 1)
The Model II variational data assimilation model is the second of the four variational models designed to blend diverse meteorological data into a dynamically constrained data set. Model II differs from Model I in that it includes the thermodynamic equation as the fifth dynamical constraint. Thus, Model II includes all five of the primative equations that govern atmospheric flow for a dry atmosphere
Application of satellite data in variational analysis for global cyclonic systems
The goal of the research is a variational data assimilation method that incorporates as dynamical constraints, the primitive equations for a moist, convectively unstable atmosphere and the radiative transfer equation. Variables to be adjusted include the three-dimensional vector wind, height, temperature, and moisture from rawinsonde data, and cloud-wind vectors, moisture, and radiance from satellite data. In order to facilitate thorough analysis of each of the model components, four variational models that divide the problem naturally according to increasing complexity were defined. The research performed during the second year fall into four areas: sensitivity studies involving Model 1; evaluation of Model 2; reformation of Model 1 for greater compatibility with Model 2; development of Model 3 (radiative transfer equation); and making the model more responsive to the observations
A Variational Assimilation Method for Satellite and Conventional Data: Development of Basic Model for Diagnosis of Cyclone Systems
A summary is presented of the progress toward the completion of a comprehensive diagnostic objective analysis system based upon the calculus of variations. The approach was to first develop the objective analysis subject to the constraints that the final product satisfies the five basic primitive equations for a dry inviscid atmosphere: the two nonlinear horizontal momentum equations, the continuity equation, the hydrostatic equation, and the thermodynamic equation. Then, having derived the basic model, there would be added to it the equations for moist atmospheric processes and the radiative transfer equation
Weakly nonlocal fluid mechanics - the Schrodinger equation
A weakly nonlocal extension of ideal fluid dynamics is derived from the
Second Law of thermodynamics. It is proved that in the reversible limit the
additional pressure term can be derived from a potential. The requirement of
the additivity of the specific entropy function determines the quantum
potential uniquely. The relation to other known derivations of Schr\"odinger
equation (stochastic, Fisher information, exact uncertainty) is clarified.Comment: major extension and revisio
Psychophysical identity and free energy
An approach to implementing variational Bayesian inference in biological
systems is considered, under which the thermodynamic free energy of a system
directly encodes its variational free energy. In the case of the brain, this
assumption places constraints on the neuronal encoding of generative and
recognition densities, in particular requiring a stochastic population code.
The resulting relationship between thermodynamic and variational free energies
is prefigured in mind-brain identity theses in philosophy and in the Gestalt
hypothesis of psychophysical isomorphism.Comment: 22 pages; published as a research article on 8/5/2020 in Journal of
the Royal Society Interfac
Ground-state phase diagram of the quantum model on the square lattice
We study the ground-state phase diagram of the quantum model on the
square lattice by means of an entangled-plaquette variational ansatz. In the
range , we find classical magnetic order of N\'eel and
collinear type, for , and
respectively. For intermediate values of the ground state is a spin
liquid (i.e., paramagnetic with no valence bond crystalline order). Our
estimates of the entanglement entropy show that such a spin liquid is
topological.Comment: 6 pages, 5 figure
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