Dynamic Stability of Ni FCC Crystal under Isotropic Tension

2013 ◽  
Vol 592-593 ◽  
pp. 47-50
Author(s):  
Petr Řehák ◽  
Miroslav Černý
Keyword(s):  
Dynamic Stability ◽  
Wave Vector ◽  
First Principles ◽  
Lattice Dynamics ◽  
Harmonic Approximation ◽  
Tensile Loading ◽  
The Other ◽  
Other Hand ◽  
Critical Strains

Lattice dynamics and stability of fcc crystal of Ni under isotropic (hydrostatic) tensile loading are studied from first principles using supercell method and a harmonic approximation. According to the results, strength of the crystal is determined by occurrence of an instability related to soft phonons with finite wave vector. On the other hand, the critical strains and stresses associated with such instabilities are only slightly lower than those related to the volumetric instability.

Walking of Long Pipelines With Multiple Buckles: Can a Trend Be Trusted?

2018 ◽  
Author(s):  
Daniel Carneiro ◽  
Andrew Rathbone
Keyword(s):  
First Principles ◽  
Gradual Increase ◽  
Axial Displacement ◽  
The Other ◽  
Full Understanding ◽  
Other Hand ◽  
Operational Temperature ◽  
Number Of Cycles ◽  
Underlying Processes ◽  
Over Time

Walking of long pipelines with multiple buckles is usually self-limiting. The buckles break the ‘long’ pipeline into multiple ‘short’ ones that are prone to walk. However, as temperature decays over the length of the pipeline, the ‘short’ sections further downstream might become cyclically constrained and eventually anchor the full pipeline length. Walking of the hot end would then slow down and cease. This tapering down can take a large number of cycles, and not seem obvious when after a fair number of cycles, a small value of accumulated axial displacement per cycle is still observed in FEA. Often, designers would stop the analyses at some stage and assume the small rate will continue indefinitely. This can be overconservative, as a limit will often exist — which is demonstrated using first principles in the paper. On the other hand, extrapolating without full understanding of the underlying processes can be dangerous. For some particular conditions, the trend can suddenly change after continuing unaltered for many cycles. This paper illustrates such change in behavior with the example of a fictitious pipeline seeing a gentle, gradual increase in operational temperature over time. The exercise shows that, after the trend has apparently settled, at a given point the rate of walking can increase again. The conditions that trigger it are shown to be predictable.

scholarly journals On the Quantum Chromatic Number of a Graph

10.37236/999 ◽  
2007 ◽  
Vol 14 (1) ◽  
Author(s):  
Peter J. Cameron ◽  
Ashley Montanaro ◽  
Michael W. Newman ◽  
Simone Severini ◽  
Andreas Winter
Keyword(s):  
Chromatic Number ◽  
Random Graphs ◽  
First Principles ◽  
Clique Number ◽  
The Other ◽  
Quantum Model ◽  
Other Hand ◽  
Orthogonal Representations

We investigate the notion of quantum chromatic number of a graph, which is the minimal number of colours necessary in a protocol in which two separated provers can convince a referee that they have a colouring of the graph.After discussing this notion from first principles, we go on to establish relations with the clique number and orthogonal representations of the graph. We also prove several general facts about this graph parameter and find large separations between the clique number and the quantum chromatic number by looking at random graphs. Finally, we show that there can be no separation between classical and quantum chromatic number if the latter is $2$, nor if it is $3$ in a restricted quantum model; on the other hand, we exhibit a graph on $18$ vertices and $44$ edges with chromatic number $5$ and quantum chromatic number $4$.

Clustering feature of metal atoms in pentacene molecular solids: first-principles study

2021 ◽  
Author(s):  
Shunta Watanabe ◽  
Yoko Tomita ◽  
Kohei Kawabata ◽  
Takashi NAKAYAMA
Keyword(s):  
Metal Atom ◽  
First Principles ◽  
The Other ◽  
Molecular Devices ◽  
Molecular Solids ◽  
First Principles Calculations ◽  
First Principles Study ◽  
Metal Atoms ◽  
Other Hand ◽  
Impurity Metal

Abstract Metal-atom contamination often induces the degradation of organic molecular devices. In this work, we studied clustering feature of Au and Al impurity metal atoms in pentacene solids by the first-principles calculations. We found that Au atoms prefer to produce clusters in a molecule-edge space due to the strong bonding among Au atoms, and such clusters can increase their sizes by producing molecule vacancies. On the other hand, Al atom prefers to locate separately around the center of pentacene molecules due to the strong bonding between Al atom and surrounding molecules, which produces the scattering distribution of Al atoms in pentacene solids.

On the Relation between the Theories of Compound Interest and Life Contingencies

1907 ◽  
Vol 41 (3) ◽  
pp. 305-348
Author(s):  
John Mayhew Allen
Keyword(s):  
First Principles ◽  
The Other ◽  
General Aspect ◽  
Integral Calculus ◽  
Infinitesimal Calculus ◽  
General Hypothesis ◽  
Other Hand ◽  
Logical Sequence ◽  
The One ◽  
Compound Interest

It has often occurred to me that but scant justice has been done to the application of the infinitesimal calculus to the theories of compound interest and life contingencies. This is, perhaps, in some measure due to the popular relegation of the differential and integral calculus to the realms of the so-called “higher mathematics.” There are, of course, two aspects of the case to be borne in mind. On the one hand, it is necessary to present the subjects in such a form as will be best suited to the student who is commencing to study them. For this purpose experience shows that a start should be made with particular cases, leaving the generalization until such time as the student shall have obtained a grasp of first principles sufficient to enable him to view the subjects in their general aspect. On the other hand, however, there is no doubt that to the reflective mind there comes a time when the desire is felt to invert the process and deduce the formulæ in their logical sequence from a fundamental general hypothesis.

scholarly journals Ground-State and Thermodynamical Properties of Uranium Mononitride from Anharmonic First-Principles Theory

2019 ◽  
Vol 9 (18) ◽  
pp. 3914 ◽  
Author(s):  
Per Söderlind ◽  
Alexander Landa ◽  
Aurélien Perron ◽  
Babak Sadigh ◽  
Tae Wook Heo
Keyword(s):  
Ground State ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Zero Temperature ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Thermodynamical Properties ◽  
Uranium Mononitride

We report on an advanced density-functional theory (DFT) approach for investigating the ground-state and thermodynamical properties of uranium mononitride (UN). The electronic structure for UN at zero temperature is obtained from DFT that utilizes the generalized gradient approximation (GGA) for the electron exchange and correlation functional and includes spin-orbit interaction and an extension with orbital polarization. Thermodynamical properties are computed within the quasi-harmonic approximation in the Debye–Grüneisen model while anharmonicity is captured in the self-consistent ab initio lattice dynamics (SCAILD) scheme. Anharmonic phonons have heretofore never been modeled from first-principles for UN but they turn out to be important. The computed free energy compares well with that of a CALPHAD (CALculation of PHAse Diagrams) assessment of available experimental data.

scholarly journals VII. On the electrolysis of secondary compounds. In a letter addressed to Michael Faraday, Esq., D. C. L. F. R. S., Fullerian Prof. Chem. Royal Institution, &c. &c. &c. By J. Frederic Daniell, Esq. F. R. S., Prof. Chem. in King's College, London

1839 ◽  
Vol 129 ◽  
pp. 97-112 ◽  
Keyword(s):  
Experimental Research ◽  
First Principles ◽  
Secondary Compounds ◽  
The Other ◽  
King's College ◽  
Other Hand ◽  
Royal Institution ◽  
The Subject ◽  
Michael Faraday

My dear Faraday, I Have no doubt that you will agree with me in thinking that the decomposition of secondary compounds by the voltaic current, particularly in connexion with water, has not yet received all the attention which it deserves, and that the subject is worthy of further experimental research. When water is present in an electrolyte, you have yourself remarked that it is probable that it is always resolved into its first principles; and, on the other hand, the early experiments of Sir H. Davy prove that when saline substances are present in water, even in the minutest quantities, they are also separated into their elements, or into their proximate principles. Whether these simultaneous decompositions bear any relation to each other, has never, that I am aware of, been made the object of inquiry.

scholarly journals Aristotle’s Method of Understanding the First Principles of Natural Things in the Physics I.1

2013 ◽  
pp. 31-50
Author(s):  
Melina G. Mouzala
Keyword(s):  
First Principles ◽  
Natural World ◽  
The Other ◽  
Perceptual Knowledge ◽  
Posterior Analytics ◽  
Other Hand ◽  
Three Stages ◽  
The One

This paper presents Aristotle’s method of understanding the first principles of natural things in the Physics I.1 and analyzes the three stages of which this method consists. In the Physics I.1, Aristotle suggests that the natural proper route which one has to follow in order to find out the first principles of natural things is to proceed from what is clearer and more knowable to us to what is more knowable and clear by nature. In the Physics I.1, the terms καθόλου (universal) and καθ΄ ἕκαστα (particular) are not used in their usual meaning (e.g., the meaning which the same terms have in the Posterior Analytics I. 2). This paper examines the Physics I.1 in comparison with the Posterior Analytics II. 19 in order to elucidate the meaning of καθόλου in the first chapter of Aristotle’s Physics. Furthermore, it reaches the conclusion that the structure of the natural world to which we belong determines the structure and the form of our knowledge. On the one hand, natural things are composite and, on the other hand, perception is involved in the initial grasping of natural things as composites. Thus, since perceptual knowledge is more accessible to us than any other kind of knowledge it is natural to reach knowledge of simple things, i.e., of the principles, starting our inquiry with the composites.

Intuition and Coherence in the Keystone Loop

2018 ◽  
pp. 108-130
Author(s):  
Keith Lehrer
Keyword(s):  
First Principles ◽  
Knowledge Claim ◽  
The Other ◽  
Wilfrid Sellars ◽  
Thomas Reid ◽  
Other Hand ◽  
A Chain ◽  
Knowledge Claims

Is knowledge and justification a matter of isolated intuition or coherence with a background system? One intuitionist, Thomas Reid, failed to acknowledge the controversy. He argued that knowledge was a matter of first principles, which drive intuition, but also claimed that the first principles depended on each other like links in a chain, as a coherentist might. Wilfrid Sellars, a famous coherentist, argued that all knowledge was explained by coherence with a background system, but, on the other hand, conceded that some knowledge claims were justified noninferentially, as an intuitionist might. This book suggests a resolution to the conflict in terms of a kind of knowledge requiring the knower be able to defend the target knowledge claim. The defense rests on exemplar representation of experience, yielding intuition, tied together in a keystone loop within a system to defend that representation, yielding coherence.

Gettering Mechanism of Cu in Silicon Calculated from First Principles

2005 ◽  
Vol 108-109 ◽  
pp. 115-124 ◽  
Author(s):  
Kazuhito Matsukawa ◽  
Nobusuke Hattori ◽  
Shigeto Maegawa ◽  
Koun Shirai ◽  
Hiroshi Katayama-Yoshida
Keyword(s):  
Molecular Dynamics ◽  
Binding Energy ◽  
Transition Metals ◽  
First Principles ◽  
Negative Charge ◽  
Positive Charge ◽  
Binding Energies ◽  
The Other ◽  
Other Hand ◽  
Dynamics Method

The binding energy between 3d transition metals (TM) such as iron (Fe), nickel (Ni) and copper (Cu), and boron (B) in Si are studied using first-principles molecular dynamics method. The binding energies of between each TM for Fe, Ni, Cu and B are 0.64,0.57,and 0.44eV respectively, and the binding energy of Fe and B is the largest, on the other hand, binding energy of Ni and B is the smallest. This result is well in agreement with the experiment fact that Fe and Cu exist as a positive charge in P+ silicon, so it is easy to combine with the B, which has a negative charge, on the other hand, Ni exists in the state of neutrality electrically in P+ silicon, so it can not combine with B atom.

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