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Articles 1 - 4 of 4
Full-Text Articles in Physics
A Selection Rule For Transitions In Pt-Symmetric Quantum Theory, Lawrence R. Mead, David Garfinkle
A Selection Rule For Transitions In Pt-Symmetric Quantum Theory, Lawrence R. Mead, David Garfinkle
Faculty Publications
Carl Bender and collaborators have developed a quantum theory governed by Hamiltonians that are PT-symmetric rather than Hermitian. To implement this theory, the inner product was redefined to guarantee positive norms of eigenstates of the Hamiltonian. In the general case, which includes arbitrary time-dependence in the Hamiltonian, a modification of the Schrödinger equation is necessary as shown by Gong and Wang to conserve probability. In this paper, we derive the following selection rule: transitions induced by time dependence in a PT-symmetric Hamiltonian cannot occur between normalized states of differing PT-norm. We show three examples of this selection rule in action: …
Depth Perception, Christopher Sirola
Depth Perception, Christopher Sirola
Faculty Publications
In most disciplines, finding the distance from one object to the next is, at least in theory, a simple operation. Not so in astronomy. While the size of Earth itself was determined with a fair degree of accuracy in ancient times, the scale of the solar system wasn’t fully understood until just a few centuries ago, and the distances to even the closest of stars wasn’t reliably determined until Friedrich Bessel measured the distance to 61 Cygni in 1838.
I Love My Baffling, Backward, Counterintuitive, Overly Complicated Magnitudes, Christopher Sirola
I Love My Baffling, Backward, Counterintuitive, Overly Complicated Magnitudes, Christopher Sirola
Faculty Publications
All professions have their jargon. But astronomy goes the extra parsec. Here’s an example. Vega, one of the brighter stars in the night sky, has an apparent magnitude (i.e., an apparent brightness) of approximately zero. Polaris, the North Star, has an apparent magnitude of about +2. Despite this, Vega appears brighter than Polaris, and not by two, but by a factor of about six times.
Use Of Multiscale Zirconium Alloy Deformation Models In Nuclear Fuel Behavior Analysis, Robert Montgomery, Carlos Tomé, Wenfeng Liu, Alankar Alankar, Gopinath Subramanian, Christopher Stanek
Use Of Multiscale Zirconium Alloy Deformation Models In Nuclear Fuel Behavior Analysis, Robert Montgomery, Carlos Tomé, Wenfeng Liu, Alankar Alankar, Gopinath Subramanian, Christopher Stanek
Faculty Publications
Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) …