1,060 research outputs found
Morphological stability of a heterophase interface under electromigration conditions
The evolution of the interface between two mutually insoluble metallic phases, under the influence of a strong electric field is examined. A slight perturbation of the interface away from a plane y=h(x) leads to a component of the electric field along the interface. This creates a diffusion flux of the individual atoms along the interface which, in turn, leads to an increase in the amplitude of the initial perturbation and thus to an interfacial profile instability. The processes is expected to be controlled by interface diffusion in response to three distinct driving forces: the electric field, internal stresses (which arise due to the accumulation or depletion of matter at the interface), and the interfacial curvature. The stress distribution along the interface was found from a self‐consistent solution of the elastic problem. For the instability to occur, differences in effective atomic charges, elastic moduli and/or atomic mobilities of the two constituent metals are required. Small sinusoidal corrugations are shown to grow with time for a range of wavelengths. The corrugations can grow monotonically or vary in oscillatory manner, depending on their wavelength. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69819/2/JAPIAU-79-9-6834-1.pd
Observation of magnetically-induced transition intensity redistribution in the onset of the hyperfine Paschen-Back regime
The Zeeman effect is an important topic in atomic spectroscopy. The induced
change in transition frequencies and amplitudes finds applications in the
Earth-field-range magnetometry. At intermediate magnetic field amplitude , where is the magnetic dipole constant
of the ground state, and is the Bohr magneton ( kG for
Cs), the rigorous rule is affected by the coupling between
magnetic sub-levels induced by the field. Transitions satisfying , referred to as magnetically-induced transitions, can be observed. Here,
we show that a significant redistribution of the Cs magnetically-induced transition intensities occurs with
increasing magnetic field. We observe that the strongest transition in the
group ( polarization) for cease to
be the strongest for . On the other hand, the strongest transition in
the group ( polarization) remains so for all
our measurements with magnetic fields up to 9 kG. These results are in
agreement with a theoretical model. The model predicts that similar
observations can be made for all alkali metals, including Na, K and Rb atoms.
Our findings are important for magnetometers utilizing the Zeeman effect above
Earth field, following the rapid development of micro-machined vapor-cell-based
sensors
Bayesian Renormalization
In this note we present a fully information theoretic approach to
renormalization inspired by Bayesian statistical inference, which we refer to
as Bayesian Renormalization. The main insight of Bayesian Renormalization is
that the Fisher metric defines a correlation length that plays the role of an
emergent RG scale quantifying the distinguishability between nearby points in
the space of probability distributions. This RG scale can be interpreted as a
proxy for the maximum number of unique observations that can be made about a
given system during a statistical inference experiment. The role of the
Bayesian Renormalization scheme is subsequently to prepare an effective model
for a given system up to a precision which is bounded by the aforementioned
scale. In applications of Bayesian Renormalization to physical systems, the
emergent information theoretic scale is naturally identified with the maximum
energy that can be probed by current experimental apparatus, and thus Bayesian
Renormalization coincides with ordinary renormalization. However, Bayesian
Renormalization is sufficiently general to apply even in circumstances in which
an immediate physical scale is absent, and thus provides an ideal approach to
renormalization in data science contexts. To this end, we provide insight into
how the Bayesian Renormalization scheme relates to existing methods for data
compression and data generation such as the information bottleneck and the
diffusion learning paradigm.Comment: 20 pages, no figures. V2: Citation format fixed, references adde
Geotechnical Forensic Investigation of Observed Cracks on a Building in Tallahassee, Florida
In July 2010, two vapor extraction wells were installed about 15 feet from a building at an angle of 50 degrees to the horizontal using rotosonic drilling technique (RDT). In June 2011, a crack approximately 0.5 inch wide on the wall of the building was reported. Several other small cracks were observed on the building following inspection by the authors. The owner of the building expressed concerns that the rotosonic drilling was the cause of the cracks and wanted assurance that subsequent drillings would not exacerbate the problem. Geotechnical forensic investigation was performed to evaluate the potential cause(s) of cracking in the building and whether future drilling would impact the building and the foundation structure system. The investigations involved performing site reconnaissance surveys, site-specific field investigations, real-time vibration monitoring, crack monitoring, and geotechnical laboratory analyses. This paper presents the results from the forensic investigations. Based on these results, potential causes for the development of cracks in the wall of the building and recommended repair measures are discussed
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