Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Magnetic Hartree-Fock equations (2)
- 4-tuple (1)
- Application (1)
- Architecture (1)
- Boudnary layer flow (1)
-
- Camassa-Holm equation (1)
- Close range (1)
- Connaught (1)
- Constant vorticity (1)
- DIT (1)
- Decay rates (1)
- Discrete spacetime (1)
- Ecclesiastical (1)
- Geomatics (1)
- Geometry (1)
- Ground state (1)
- Hamiltonian formulation (1)
- History of architecture (1)
- Ionization (1)
- Ireland (1)
- Langer's theory (1)
- Lattice (1)
- Lax pair (1)
- Mathematics (1)
- Medieval (1)
- Metastable states (1)
- Momentum map (1)
- No-slip (1)
- Nonresonant cosmic-ray current-driven instability (1)
- Ormond (1)
Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Langer's Method For The Calculation Of Escape Rates And Its Application To Systems Of Ferromagnets, Gerard Duff
Langer's Method For The Calculation Of Escape Rates And Its Application To Systems Of Ferromagnets, Gerard Duff
Doctoral
This work is a study of the application of a theory proposed by J. S. Langer (J.S. Langer, Statistical Theory of the Decay of Metastable States, Annals of Physics 54, 258-275 (1969)) for the calculation of the decay rate (relaxation rate) of a metastable state. The theory is set in the context of statistical mechanics, where the dynamics of a system with a large number of degrees of freedom (order 1023) are reduced to N degrees of freedom, where N is small, when a steady state or equilibrium position is maintained by the entire system. In this thesis N equals …
Environmental Limits On The Nonresonant Cosmic-Ray Current-Driven Instability, Brian Reville, John Kirk, Peter Duffy, Stephen O'Sullivan
Environmental Limits On The Nonresonant Cosmic-Ray Current-Driven Instability, Brian Reville, John Kirk, Peter Duffy, Stephen O'Sullivan
Articles
We investigate the so-called nonresonant cosmic-ray streaming instability, first discussed by Bell (2004). The extent to which thermal damping and ion-neutral collisions reduce the growth of this instability is calculated. Limits on the growth of the nonresonant mode in SN1006 and RX J1713.7-3946 are presented.
Some Rather Mechanical Reflections On Symmetry: In Art, Science, Engineering, Mathematics, Etc., Jim Mcgovern
Some Rather Mechanical Reflections On Symmetry: In Art, Science, Engineering, Mathematics, Etc., Jim Mcgovern
Articles
This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections on symmetry in diverse areas such as art, science, engineering, mathematics, etc. I explain what symmetry is to me, giving examples with lots of images and mentioning or at least barely referencing art, science, architecture, engineering, heritage, cosmology, bicycles, flight, invention, ingenuity, history, wallpaper, mathematics, typography, structures, regular shapes, coordinate systems, spacetime, thermodynamics and suchlike.
An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance (Revised Version) 2008, Jim Mcgovern
An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance (Revised Version) 2008, Jim Mcgovern
Conference Papers
A particular discrete rhombohedral lattice consisting of four symmetrically interlaced cuboctahedral point lattices is described that is interesting because of the high degree of symmetry it exhibits. The four constituent cuboctahedral lattices are denoted by four colours and the composite lattice is referred to as a 4-colour rhombohedral lattice. Each point of the 4-colour lattice can be referenced by an integer 4-tuple containing only the positive non-zero integers (the counting numbers). The relationship between the discrete rhombohedral lattice and a discrete Cartesian lattice is explained. Some interesting aspects of the lattice and of the counting-number 4-tuple coordinate system are pointed …
Metrology And Proportion In The Ecclesiastical Architecture Of Medieval Ireland, Avril Behan, Rachel Moss
Metrology And Proportion In The Ecclesiastical Architecture Of Medieval Ireland, Avril Behan, Rachel Moss
Conference Papers
The aim of this paper is to examine the extent to which detailed empirical analysis of the metrology and proportional systems used in the design of Irish ecclesiastical architecture can be analysed to provide historical information not otherwise available. Focussing on a relatively limited sample of window tracery designs as a case study, it will first set out to establish what, if any, systems were in use, and then what light these might shed on the background, training and work practices of the masons, and, by association, the patrons responsible for employing them.
An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance, Jim Mcgovern
An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance, Jim Mcgovern
Conference Papers
A particular discrete rhombohedral lattice consisting of four symmetrically interlaced cuboctahedral or cubic point lattices is described that is interesting because of the high degree of symmetry it exhibits. The four constituent lattices are denoted by four colours and the composite lattice is referred to as a 4-colour rhombohedral lattice. Each point of the 4-colour lattice can be referenced by an integer 4-tuple containing only the positive non-zero integers (the counting numbers). The relationship between the discrete rhombohedral lattice and a discrete Cartesian lattice is explained. Some interesting aspects of the lattice and of the counting-number 4-tuple coordinate system are …
The Dublin Institute Of Technology And University Status: A Case Study Of The Application By Dit For Designation As A University (1996-99), Colm Garvey
Other resources
Section 9 of the Universities Act 1997 set out, for the first time, a statutory mechanism for the establishment of a new university in Ireland. The Dublin Institute of Technology (DIT) was the first institution to be granted a review under this legislation. This thesis presents an account and analysis of how the application for university title was handled by an international review group, by the Higher Education Authority (HEA) and by the Irish Government. This case study is based on access to files held by the HEA and on interviews with some of the leading players in the Review …
Non-Existence Of A Minimizer To The Hartree-Fock Functional, Michael Melgaard, Mattias Enstedt
Non-Existence Of A Minimizer To The Hartree-Fock Functional, Michael Melgaard, Mattias Enstedt
Articles
In the presence of an external magnetic field, we prove absence of a ground state within the Hartree-Fock theory of atoms and molecules. The result is established for a wide class of magnetic fields when the number of electrons is greater than or equal to 2Z + K, where Z is the total charge of K nuclei. Positivity properties are instrumental in the proof of this bound for the maximal ionization
On An Integrable Two-Component Camassa-Holm Shallow Water System, Adrian Constantin, Rossen Ivanov
On An Integrable Two-Component Camassa-Holm Shallow Water System, Adrian Constantin, Rossen Ivanov
Articles
The interest in the Camassa-Holm equation inspired the search for various generalizations of this equation with interesting properties and applications. In this letter we deal with such a twocomponent integrable system of coupled equations. First we derive the system in the context of shallow water theory. Then we show that while small initial data develop into global solutions, for some initial data wave breaking occurs. We also discuss the solitary wave solutions. Finally, we present an explicit construction for the peakon solutions in the short wave limit of system.
Existence Of A Solution To Hartree-Fock Equations With Decreasing Magnetic Field, Mattias Enstedt, Michael Melgaard
Existence Of A Solution To Hartree-Fock Equations With Decreasing Magnetic Field, Mattias Enstedt, Michael Melgaard
Articles
In the presence of an external magnetic field, we prove existence of a ground state within the Hartree–Fock theory of atoms and molecules. The ground state exists provided the magnetic field decreases at infinity and the total charge of nuclei exceeds , where is the number of electrons. In the opposite direction, no ground state exists if .
Higher Derivatives Of Spectral Functions Associated With One-Dimensional Schrodinger Operators, Daphne Gilbert, B.J. Harris, S.M. Riehl
Higher Derivatives Of Spectral Functions Associated With One-Dimensional Schrodinger Operators, Daphne Gilbert, B.J. Harris, S.M. Riehl
Articles
We investigate the existence and asymptotic behaviour of higher derivatives of the spectral function in the context of one-dimensional Schr¨odinger operators on the half-line with integrable potentials. In particular, we identify sufficient conditions on the potential for the existence and continuity of the n-th derivative, and outline a systematic procedure for estimating numerical upper bounds for the turning points of such derivatives. Explicit worked examples illustrate the development and application of the theory.
A Study Of Boundary Layer Fflow With No-Slip And Slip Boundary Conditions, Sandra B. Spillane
A Study Of Boundary Layer Fflow With No-Slip And Slip Boundary Conditions, Sandra B. Spillane
Doctoral
This thesis involves solving the two-dimensional boundary layer equations for axially symmetric fluid flow along a circular cylinder using the no-slip and slip boundary condition, and along a flat plate with the slip boundary condition. Initially, historical results in both areas are summarised. The research section of this thesis is concerned with extending these historical results. In the first research chapters, a Pade approximation and an Euler transformation are used to greatly extend the region of validity of the historical results. Following that is an investigation of the relaxation of the traditional no-slip boundary condition, which usually occurs when there …
Algebraic Discretization Of The Camassa-Holm And Hunter-Saxton Equations, Rossen Ivanov
Algebraic Discretization Of The Camassa-Holm And Hunter-Saxton Equations, Rossen Ivanov
Articles
The Camassa-Holm (CH) and Hunter-Saxton (HS) equations have an interpretation as geodesic flow equations on the group of diffeomorphisms, preserving the H1 and H.1 right-invariant metrics correspondingly. There is an analogy to the Euler equations in hydrodynamics, which describe geodesic flow for a right-invariant metric on the infinitedimensional group of diffeomorphisms preserving the volume element of the domain of fluid flow and to the Euler equations of rigid body whith a fixed point, describing geodesics for a left-invariant metric on SO(3). The CH and HS equations are integrable bi-hamiltonian equations and one of their Hamiltonian structures is associated to the …
Nearly-Hamiltonian Structure For Water Waves With Constant Vorticity, Adrian Constantin, Rossen Ivanov, Emil Prodanov
Nearly-Hamiltonian Structure For Water Waves With Constant Vorticity, Adrian Constantin, Rossen Ivanov, Emil Prodanov
Articles
We show that the governing equations for two-dimensional gravity water waves with constant non-zero vorticity have a nearly-Hamiltonian structure, which becomes Hamiltonian for steady waves.