21,013 research outputs found
A generalized Schroedinger equation for loop quantum cosmology
A temporally discrete Schroedinger time evolution equation is proposed for
isotropic quantum cosmology coupled to a massless scalar source. The approach
employs dynamically determined intrinsic time and produces the correct
semiclassical limit.Comment: 5 pages, to appear in the Proceedings of the Eleventh Marcel
Grossmann Meetin
Distinguishing Hidden Markov Chains
Hidden Markov Chains (HMCs) are commonly used mathematical models of
probabilistic systems. They are employed in various fields such as speech
recognition, signal processing, and biological sequence analysis. We consider
the problem of distinguishing two given HMCs based on an observation sequence
that one of the HMCs generates. More precisely, given two HMCs and an
observation sequence, a distinguishing algorithm is expected to identify the
HMC that generates the observation sequence. Two HMCs are called
distinguishable if for every there is a distinguishing
algorithm whose error probability is less than . We show that one
can decide in polynomial time whether two HMCs are distinguishable. Further, we
present and analyze two distinguishing algorithms for distinguishable HMCs. The
first algorithm makes a decision after processing a fixed number of
observations, and it exhibits two-sided error. The second algorithm processes
an unbounded number of observations, but the algorithm has only one-sided
error. The error probability, for both algorithms, decays exponentially with
the number of processed observations. We also provide an algorithm for
distinguishing multiple HMCs. Finally, we discuss an application in stochastic
runtime verification.Comment: This is the full version of a LICS'16 pape
Optical spectroscopy study on pressure-induced phase transitions in the three-dimensional Dirac semimetal CdAs
We report a room-temperature optical reflectivity study performed on
[112]-oriented CdAs single crystals over a broad energy range under
external pressure up to 10 GPa. The abrupt drop of the band dispersion
parameter (-parameter) and the interruption of the gradual redshift of the
bandgap at 4~GPa confirms the structural phase transition from a
tetragonal to a monoclinic phase in this material. The pressure-induced
increase of the overall optical conductivity at low energies and the continuous
redshift of the high-energy bands indicate that the system evolves towards a
topologically trivial metallic state, although a complete closing of the band
gap could not be observed in the studied pressure range. Furthermore, a
detailed investigation of the low-pressure regime suggests the possible
existence of an intermediate state between 2 and 4~GPa , that might be a
precursor of the structural phase transition or due to the lifted degeneracy of
the Dirac nodes. Several optical parameters show yet another anomaly at 8~GPa,
where low-temperature superconductivity was found in an earlier study.Comment: submitted to PR
Boundary layer simulator improvement
Boundary Layer Integral Matrix Procedure (BLIMPJ) has been identified by the propulsion community as the rigorous boundary layer program in connection with the existing JANNAF reference programs. The improvements made to BLIMPJ and described herein have potential applications in the design of the future Orbit Transfer Vehicle engines. The turbulence model is validated to include the effects of wall roughness and a way is devised to treat multiple smooth-rough surfaces. A prediction of relaminarization regions is examined as is the combined effects of wall cooling and surface roughness on relaminarization. A turbulence model to represent the effects of constant condensed phase loading is given. A procedure is described for thrust decrement calculation in thick boundary layers by coupling the T-D Kinetics Program and BLIMPJ and a way is provided for thrust loss optimization. Potential experimental studies in rocket nozzles are identified along with the required instrumentation to provide accurate measurements in support of the presented new analytical models
Metal contacts to lowly doped Si and ultra thin SOI
We present our investigations on the fabrication of ohmic and Schottky contacts of several metals on lowly doped bulk Si and SOI wafers. Through this paper we evaluate the fabrication of rectifying devices in which no doping is intentionally introduced
- …