452 research outputs found
Factorization and Entanglement in Quantum Systems
We discuss the question of entanglement versus separability of pure quantum
states in direct product Hilbert spaces and the relevance of this issue to
physics. Different types of separability may be possible, depending on the
particular factorization or split of the Hilbert space. A given orthonormal
basis set for a Hilbert space is defined to be of type (p,q) if p elements of
the basis are entangled and q are separable, relative to a given bi-partite
factorization of that space. We conjecture that not all basis types exist for a
given Hilbert space.Comment: 11 page
Classical and Quantum Causality in Quantum Field Theory. Or, "The Quantum Universe"
Based on a number of experimentally verified physical observations, it is
argued that the standard principles of quantum mechanics should be applied to
the Universe as a whole. Thus, a paradigm is proposed in which the entire
Universe is represented by a pure state wavefunction contained in a
factorisable Hilbert space of enormous dimension, and where this statevector is
developed by successive applications of operators that correspond to unitary
rotations and Hermitian tests. Moreover, because by definition the Universe
contains everything, it is argued that these operators must be chosen
self-referentially; the overall dynamics of the system is envisaged to be
analogous to a gigantic, self-governing, quantum computation. The issue of how
the Universe could choose these operators without requiring or referring to a
fictitious external observer is addressed.
The processes by which conventional physics might be recovered from this
fundamental, mathematical and global description of reality are particularly
investigated. Specifically, it is demonstrated that by considering the changing
properties, separabilities and factorisations of both the state and the
operators as the Universe proceeds though a sequence of discrete computations,
familiar notions such as classical distinguishability, particle physics, space,
time, special relativity and endo-physical experiments can all begin to emerge
from the proposed picture. A pregeometric vision of cosmology is therefore
discussed, with all of physics ultimately arising from the relationships
occurring between the elements of the underlying mathematical structure.Comment: 398 pages, 9 figures. Thesis submitted to the University of
Nottingham for the degree of Doctor of Philosophy, April 200
Initiation of failure mechanisms in glass- resin composites
Failure mechanisms of glass-resin composites - flat sided rectangular microtape to measure strain and effects on castings of shrinkag
ENVIRONMENTAL ACCOUNTS: TIME SERIES + ECO-TAXES
This study was commissioned by the European Commission in cooperation with Eurostat with the
objective of improving and extending the scope of the environmental accounts for Ireland. It follows
two previous studies, Pilot Environmental Accounts published by the Central Statistics Office and the
Satellite Environmental Accounts for Ireland 1996, unpublished report to Eurostat (2000). As indicated
in the title, this study presents time series, which in some cases are of considerable length, and provides
information on what could loosely be called eco-taxes. Additionally, where feasible the study relates
environmental information to the underlying economic magnitudes and movements, and broadens the
information considerably.
The report consists of three self-contained sections. The sections cover (1) emissions to air, (2)
discharges to water and (3) disposals of solid waste and these three types of releases to the environment
are disaggregated according to NACE Rev 1 by five major economic sectors:
Agriculture/forestry/fishing
Energy transformation
Industry
Transport
Services
Households
though in some areas the breakdown is unavoidably less detailed and it is more detailed in others.
Section 1 on emissions to air concentrates on greenhouse gases and on improving the underlying
information on energy use. Behavioural analyses have been hampered in the past by inadequate time-series
of energy-related prices and taxes so that a large effort was devoted here to presenting coherent
time-series of these items
Studies of hollow multipartitioned ceramic structures
Drawing of glass fiber into hollow cross sections of various shape
Symmetries and Systematics of Doubly Heavy Hadrons
We discuss the extension of the superflavor symmetry of doubly heavy baryons
to states which contain an excited heavy diquark, and we examine some of the
consequences of this symmetry for the spectra of doubly heavy baryons and heavy
mesons. We explore the ramifications of a proposed symmetry that relates heavy
diquarks to doubly heavy mesons. We present a method for determining how the
excitation energy of a system containing two heavy quarks will scale as one
changes the strength of the interactions and the reduced mass of the system. We
use this to derive consequences of the heavy diquark-doubly heavy meson
symmetry. We compare these consequences to the results of a quark model as well
as the experimental data for doubly and singly heavy mesons. We also discuss
the possibility of treating the strange quark as a heavy quark and apply the
ideas developed here to strange hadrons.Comment: 23 pages, 2 figures, and 17 tables include
Plate-impact loading of cellular structures formed by selective laser melting
Porous materials are of great interest because of improved energy absorption over their solid counterparts. Their properties, however, have been difficult to optimize. Additive manufacturing has emerged as a potential technique to closely define the structure and properties of porous components, i.e. density, strut width and pore size; however, the behaviour of these materials at very high impact energies remains largely unexplored. We describe an initial study of the dynamic compression response of lattice materials fabricated through additive manufacturing. Lattices consisting of an array of intersecting stainless steel rods were fabricated into discs using selective laser melting. The resulting discs were impacted against solid stainless steel targets at velocities ranging from 300 to 700 m s-1 using a gas gun. Continuum CTH simulations were performed to identify key features in the measured wave profiles, while 3D simulations, in which the individual cells were modelled, revealed details of microscale deformation during collapse of the lattice structure. The validated computer models have been used to provide an understanding of the deformation processes in the cellular samples. The study supports the optimization of cellular structures for application as energy absorbers. © 2014 IOP Publishing Ltd
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