2,066 research outputs found
Strategy updating rules and strategy distributions in dynamical multiagent systems
In the evolutionary version of the minority game, agents update their
strategies (gene-value ) in order to improve their performance. Motivated by
recent intriguing results obtained for prize-to-fine ratios which are smaller
than unity, we explore the system's dynamics with a strategy updating rule of
the form (). We find that the strategy
distribution depends strongly on the values of the prize-to-fine ratio , the
length scale , and the type of boundary condition used. We show that
these parameters determine the amplitude and frequency of the the temporal
oscillations observed in the gene space. These regular oscillations are shown
to be the main factor which determines the strategy distribution of the
population. In addition, we find that agents characterized by
(a coin-tossing strategy) have the best chances of survival at asymptotically
long times, regardless of the value of and the boundary conditions
used.Comment: 4 pages, 7 figure
Dynamical quenching and annealing in self-organization multiagent models
We study the dynamics of a generalized Minority Game (GMG) and of the Bar
Attendance Model (BAM) in which a number of agents self-organize to match an
attendance that is fixed externally as a control parameter. We compare the
usual dynamics used for the Minority Game with one for the BAM that makes a
better use of the available information. We study the asymptotic states reached
in both frameworks. We show that states that can be assimilated to either
thermodynamic equilibrium or quenched configurations can appear in both models,
but with different settings. We discuss the relevance of the parameter that
measures the value of the prize for winning in units of the fine for losing. We
also provide an annealing protocol by which the quenched configurations of the
GMG can progressively be modified to reach an asymptotic equlibrium state that
coincides with the one obtained with the BAM.Comment: around 20 pages, 10 figure
Quantum tomography via equidistant states
We study the possibility of performing quantum state tomography via
equidistant states. This class of states allows us to propose a non-symmetric
informationally complete POVM based tomographic scheme. The scheme is defined
for odd dimensions and involves an inversion which can be analytically carried
out by Fourier transform
SOLUTION OF 1D AND 2D POISSON'S EQUATION BY USING WAVELET SCALING FUNCTIONS
The use of multiresolution techniques and wavelets has become increasingly popular in the development of numerical schemes for the solution of partial differential equations (PDEs). Therefore, the use of wavelet scaling functions as a basis in computational analysis holds some promise due to their compact support, orthogonality and localization properties. Daubechies and Deslauriers-Dubuc functions have been successfully used as basis functions in several schemes like the Wavelet- Galerkin Method (WGM) and the Wavelet Finite Element Method (WFEM). Another possible advantage of their use is the fact that the calculation of integrals of inner products of wavelet scaling functions and their derivatives can be made by solving a linear system of equations, thus avoiding the problem of using approximations by some numerical method. These inner products were defined as connection coefficients and they are employed in the calculation of stiffness matrices and load vectors. In this work, some mathematical foundations regarding wavelet scaling functions, their derivatives and connection coefficients are reviewed. A scheme based on the Galerkin Method is proposed for the direct solution of Poisson's equation (potential problems) in a meshless formulation using interpolating wavelet scaling functions (Interpolets). The applicability of the proposed method and some convergence issues are illustrated by means of a few examples
Future Nuisance Flooding in Norfolk, VA, From Astronomical Tides and Annual to Decadal Internal Climate Variability
Increasing sea level rise will lead to more instances of nuisance flooding along the Virginia coastline in the coming decades, causing road closures and deteriorating infrastructure. These minor flood events can be caused by astronomical tides alone, in addition to internal climate variability on annual to decadal timescales. An assessment of nuisance flooding from these two effects is presented up until the year 2050 for Norfolk, Virginia. The analysis of water levels indicates that nuisance flooding from tides alone in conjunction with a medium-high sea level scenario will result in flooding beginning in 2030 with frequency increasing thereafter. The addition of climate variability, by use of an empirical mode decomposition, leads to a substantial increase of flooding relative to the tides-alone analysis and shows flood events beginning as soon as 2020. High tides in the future will produce nuisance flooding without the need of other drivers such as coastal storms. Plain Language Summary As sea level continues to rise, coastal cities are going to start to see increases in nuisance flooding. This minor flooding is generally caused by tides and wind events, leading to inundation that over time deteriorates roads and infrastructure. Nuisance flooding in Norfolk, Virginia, has increased 325% since 1960 and is becoming more prominent. By combining sea level estimates, tidal estimates, and natural internal climate variability contributions to sea level rise, we have determined how nuisance flooding will increase in the future for Norfolk up until the year 2050. Our analyses show that this flooding will continue to increase in frequency with time, with a potential for well over 200 flood events in the year 2049
Food value chain development in Central New York: CNY bounty
Includes bibliographical references (pages 139-141).In the past 10 years, demand for locally grown food has increased dramatically. Concomitantly, small, commercial farms have declined disproportionately to small and large farms. The decline may be due to the lack of appropriately scaled marketing and distribution resulting from changing markets. This article presents a case study of a component of a food value chain started in 2007, Central New York (CNY) Bounty. CNY Bounty markets and distributes products produced by 119 small, commercial farms and processors to individual households, restaurants, natural food stores, and universities. In the past four years, CNY Bounty has experienced mixed success in terms of its economic viability, which can offer some important lessons for practitioners and contributions for food value chain research
Temporal oscillations and phase transitions in the evolutionary minority game
The study of societies of adaptive agents seeking minority status is an
active area of research. Recently, it has been demonstrated that such systems
display an intriguing phase-transition: agents tend to {\it self-segregate} or
to {\it cluster} according to the value of the prize-to-fine ratio, . We
show that such systems do {\it not} establish a true stationary distribution.
The winning-probabilities of the agents display temporal oscillations. The
amplitude and frequency of the oscillations depend on the value of . The
temporal oscillations which characterize the system explain the transition in
the global behavior from self-segregation to clustering in the case.Comment: 5 pages, 5 figure
Self-Segregation vs. Clustering in the Evolutionary Minority Game
Complex adaptive systems have been the subject of much recent attention. It
is by now well-established that members (`agents') tend to self-segregate into
opposing groups characterized by extreme behavior. However, while different
social and biological systems manifest different payoffs, the study of such
adaptive systems has mostly been restricted to simple situations in which the
prize-to-fine ratio, , equals unity. In this Letter we explore the dynamics
of evolving populations with various different values of the ratio , and
demonstrate that extreme behavior is in fact {\it not} a generic feature of
adaptive systems. In particular, we show that ``confusion'' and
``indecisiveness'' take over in times of depression, in which case cautious
agents perform better than extreme ones.Comment: 4 pages, 4 figure
Quantitative analysis of shadow X-ray Magnetic Circular Dichroism Photo-Emission Electron Microscopy
Shadow X-ray Magnetic Circular Dichroism Photo-Emission Electron Microscopy
(XMCD-PEEM) is a recent technique, in which the photon intensity in the shadow
of an object lying on a surface, may be used to gather information about the
three-dimensional magnetization texture inside the object. Our purpose here is
to lay the basis of a quantitative analysis of this technique. We first discuss
the principle and implementation of a method to simulate the contrast expected
from an arbitrary micromagnetic state. Text book examples and successful
comparison with experiments are then given. Instrumental settings are finally
discussed, having an impact on the contrast and spatial resolution : photon
energy, microscope extraction voltage and plane of focus, microscope background
level, electric-field related distortion of three-dimensional objects, Fresnel
diffraction or photon scattering
New Superhard Phases for 3D C60-based Fullerites
We have explored new possible phases of 3D C60-based fullerites using
semiempirical potentials and ab-initio density functional methods. We have
found three closely related structures - two body centered orthorhombic and one
body centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule.
These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and
shear moduli around 240 GPa, which make them good candidates for new low
density superhard materials.Comment: To be published in Physical Review Letter
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