Search results for "model theory"
showing 10 items of 681 documents
Quantum Field Theory
2018
Quantum field theory (QFT) shares many of its philosophical problems with quantum mechanics. This applies in particular to the quantum measurement process and the connected interpretive problems, to which QFT contributes hardly any new aspects, let alone solutions. The question as to how the objects described by the theory are spatially embedded was already also discussed for quantum mechanics. However, the new mathematical structure of QFT promises new answers, which renders the spatiotemporal interpretation of QFT the pivotal question. In this chapter, we sketch the mathematical characteristics of QFT and show that a particle as well as a field interpretation breaks down.
1H and 13C shielding measurements in comparison with DFT calculations performed for two 2-(acetyloamino)-N,N-dimethyl-3-phenylacrylamide isomers
2015
Abstract We present measurements of 1H and 13C shielding for (2E)- and (2Z)-2-(acetyloamino)-N,N-dimethyl-3-phenylacrylamide isomers in solutions. Practically the same values of the shielding were obtained using internal and external referencing. For the interpretation, we explore DFT calculations of shieldings performed at the rovibrationally averaged geometries. The comparison of the experimental and theoretical results is verified both for the shielding and chemical shift. It appears that some inaccuracies in the calculations of the chemical shift can be reduced due to the error compensation while subtracting the reference shielding. As shown the measurement of magnetic shielding can be …
Analogical Modeling and Numerical Simulation for Sintering Phenomena
2013
In this paper the authors propose an approach for analogical modeling and numerical simulation of the phenomena of sintering, taking into account different cases depending on the type of energy used in the process of aggregation and the nature of the material powder, using a software which simulates the propagation and the control of the temperature. Many physical phenomena encountered in science and engineering can be described mathematically through partial differential equations (PDE) and ordinary differential equations (ODE) such as propagation phenomena, engineering applications, hydrotechnics, chemistry, pollution a.s.o. There may be situations when the exact establish of the analytic…
Thermodynamic class II Szekeres-Szafron solutions. Singular models
2019
A family of parabolic Szekeres-Szafron class II solutions in local thermal equilibrium is studied and their associated thermodynamics are obtained. The subfamily with the hydrodynamic behavior of a generic ideal gas (defined by the equation of state $p = k n \Theta$) results to be an inhomogeneous generalization of flat FLRW $\gamma$-law models. Three significative interpretations that follow on from the choice of three specific thermodynamic schemes are analyzed in depth. First, the generic ideal gas in local thermal equilibrium; this interpretation leads to an inhomogeneous temperature $\Theta$. Second, the thermodynamics with homogeneous temperature considered by Lima and Tiomno (CQG 6 1…
A relational model for unstructured documents
1987
The logical structure of a document is usually a tree in which the order of the nodes is important at least at some level of the tree. We call a document unstructured if its structure is a single-level ordered tree. The purpose of this paper is to present a many-sorted algebra for handling unstructured documents. The documents in the model are represented by relations. An algebra for handling documents of one type can be extended to an algebra for handling documents of several types. Further, an algebra for handling documents can be extended by the relational algebra for handling documents and relations in a common algebra. The model of this paper can be regarded as a part of a general docu…
The Fuzzy Logic Gambit as a Paradigm of Lotfi’s Proposals
2019
Lotfi Zadeh, in discussing the future directions the discipline should have taken, has insisted in highlighting what he called `the Fuzzy Logic Gambit' , whose basic idea is that, when dealing with the solution of a problem through the use of Fuzzy Logic, two different type of precisions exist: ``precision in value'', which is connected to the ability of measuring reality, and ``precision in meaning'', which is what we want to attain when dealing with the real world. While the final goal of Fuzzy Logic is to provide some degree of precision to what is less precise in nature, he has brilliantly suggested that this can be obtained by bartering between precision in value and precision in meani…
Nonlocal Second Order Vehicular Traffic Flow Models And Lagrange-Remap Finite Volumes
2011
In this paper a second order vehicular macroscopic model is derived from a microscopic car–following type model and it is analyzed. The source term includes nonlocal anticipation terms. A Finite Volume Lagrange–remap scheme is proposed.
Prediction of Molecular Volume and Surface of Alkanes by Molecular Topology.
2003
Molecular volume and molecular surface are expressed as a function of topological degree in alkane graphs. This allows not only a straightforward approach to calculate such physicochemical magnitudes but also an interpretation of the role of the local vertex invariant (LOVI) or valence degree, delta, as well as the connectivity indices in the prediction of physicochemical properties. The interpretation is based on the concept of molecular accessibility (as introduced by Estrada, J. Phys. Chem. A 2002, 106, 9085) for which precise mathematical definitions are provided.
Numerical study of blow-up in solutions to generalized Kadomtsev-Petviashvili equations
2013
We present a numerical study of solutions to the generalized Kadomtsev-Petviashvili equations with critical and supercritical nonlinearity for localized initial data with a single minimum and single maximum. In the cases with blow-up, we use a dynamic rescaling to identify the type of the singularity. We present a discussion of the observed blow-up scenarios.
Pseudodifferential operators of Beurling type and the wave front set
2008
AbstractWe investigate the action of pseudodifferential operators of Beurling type on the wave front sets. More precisely, we show that these operators are microlocal, that is, preserve or reduce wave front sets. Some consequences on micro-hypoellipticity are derived.