156,918 research outputs found
Finding The Sign Of A Function Value By Binary Cellular Automaton
Given a continuous function , suppose that the sign of only has
finitely many discontinuous points in the interval . We show how to use
a sequence of one dimensional deterministic binary cellular automata to
determine the sign of where is the (number) density of 1s in
an arbitrarily given bit string of finite length provided that satisfies
certain technical conditions.Comment: Revtex, uses amsfonts, 10 page
Attractive Hubbard Model on a Honeycomb Lattice
We study the attractive fermionic Hubbard model on a honeycomb lattice using
determinantal quantum Monte Carlo simulations. By increasing the interaction
strength U (relative to the hopping parameter t) at half-filling and zero
temperature, the system undergoes a quantum phase transition at 5.0 < U_c/t <
5.1 from a semi-metal to a phase displaying simultaneously superfluid behavior
and density order. Doping away from half-filling, and increasing the
interaction strength at finite but low temperature T, the system always appears
to be a superfluid exhibiting a crossover between a BCS and a molecular regime.
These different regimes are analyzed by studying the spectral function. The
formation of pairs and the emergence of phase coherence throughout the sample
are studied as U is increased and T is lowered
Fluctuations of Entropy Production in Partially Masked Electric Circuits: Theoretical Analysis
In this work we perform theoretical analysis about a coupled RC circuit with
constant driven currents. Starting from stochastic differential equations,
where voltages are subject to thermal noises, we derive time-correlation
functions, steady-state distributions and transition probabilities of the
system. The validity of the fluctuation theorem (FT) is examined for scenarios
with complete and incomplete descriptions.Comment: 4 pages, 1 figur
Relation Between Quantum Speed Limits And Metrics On U(n)
Recently, Chau [Quant. Inform. & Comp. 11, 721 (2011)] found a family of
metrics and pseudo-metrics on -dimensional unitary operators that can be
interpreted as the minimum resources (given by certain tight quantum speed
limit bounds) needed to transform one unitary operator to another. This result
is closely related to the weighted -norm on . Here we
generalize this finding by showing that every weighted -norm on
with 1\le p \le \limitingp induces a metric and a
pseudo-metric on -dimensional unitary operators with quantum
information-theoretic meanings related to certain tight quantum speed limit
bounds. Besides, we investigate how far the correspondence between the
existence of metrics and pseudo-metrics of this type and the quantum speed
limits can go.Comment: minor amendments, 6 pages, to appear in J.Phys.
Energy-efficiency improvements for optical access
This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied
Geophysical Methods: an Overview
Geophysics is expected to have a major role in lunar resource assessment when manned systems return to the Moon. Geophysical measurements made from a lunar rover will contribute to a number of key studies: estimating regolith thickness, detection of possible large-diameter lava tubes within maria basalts, detection of possible subsurface ice in polar regions, detection of conductive minerals that formed directly from a melt (orthomagmatic sulfides of Cu, Ni, Co), and mapping lunar geology beneath the regolith. The techniques that can be used are dictated both by objectives and by our abilities to adapt current technology to lunar conditions. Instrument size, weight, power requirements, and freedom from orientation errors are factors we have considered. Among the geophysical methods we believe to be appropriate for a lunar resource assessment are magnetics, including gradiometry, time-domain magnetic induction, ground-penetrating radar, seismic reflection, and gravimetry
A Field Test Study on Instrumented Soil Nail Installed in Cut Slope
Soil nailing is a technique routinely used in Hong Kong whereby closely spaced steel bars are installed into a slope so that its stability conditions can be improved. A full-scale field test has been carried out by The Department of Civil Engineering of The University of Hong Kong to study the development of passive load along the full length of soil nails when subjected to induced rise in groundwater table. The cut slope was formed to a very steep angle of 55° and 10 m high in completely decomposed volcanic material. Grouted curtain was also formed behind, at the bottom and on both ends of the slope in order to form an impermeable barrier that would allow groundwater table to increase artificially by injecting water into slotted PVC pipes. Nine number of soil nails (in regular 2 m c/c spacing of 3 rows and 3 columns) of 6 m long high yield steel bar were installed at 15° from horizontal into the formed cut slope. Instrumentation included strain gauges along the nails, inclinometers, piezometers, and settlement prisms. This paper describes the method of construction and the load developed along the soil nails when the groundwater table was raised to the ground surface. It was found that the measured passive load along the soil nail was smaller than the commonly assumed design parameters, an indication that substantial savings can be achieved if mobilization of shearing resistance along the full length of the soil nail was considered in routine design. Finite element analysis has also been carried out to compare the measured load with the simulated load and the stability factor is compared with the factor of safety at each stage of loading
Non-degenerate solutions of universal Whitham hierarchy
The notion of non-degenerate solutions for the dispersionless Toda hierarchy
is generalized to the universal Whitham hierarchy of genus zero with
marked points. These solutions are characterized by a Riemann-Hilbert problem
(generalized string equations) with respect to two-dimensional canonical
transformations, and may be thought of as a kind of general solutions of the
hierarchy. The Riemann-Hilbert problem contains arbitrary functions
, , which play the role of generating functions of
two-dimensional canonical transformations. The solution of the Riemann-Hilbert
problem is described by period maps on the space of -tuples
of conformal maps from disks of the
Riemann sphere and their complements to the Riemann sphere. The period maps are
defined by an infinite number of contour integrals that generalize the notion
of harmonic moments. The -function (free energy) of these solutions is also
shown to have a contour integral representation.Comment: latex2e, using amsmath, amssym and amsthm packages, 32 pages, no
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