87,203 research outputs found
Theory of the evolutionary minority game
We present a theory which describes a recently introduced model of an
evolving, adaptive system in which agents compete to be in the minority. The
agents themselves are able to evolve their strategies over time in an attempt
to improve their performance. The present theory explicitly demonstrates the
self-interaction, or so-called market impact, that agents in such systems
experience
Total-pressure measurement in pulsating flows
Pneumatic-type probe was used as comparison instrument with total pressure tubes to determine true average pressure and, thus, to determine if nonlinear averaging effects were significant. Since pneumatic probe is more complicated to use than a total-pressure tube, it is used only as a comparison instrument to determine extent of averaging effects
Molecular-Kinetic Simulations of Escape from the Ex-planet and Exoplanets: Criterion for Transonic Flow
The equations of gas dynamics are extensively used to describe atmospheric
loss from solar system bodies and exoplanets even though the boundary
conditions at infinity are not uniquely defined. Using molecular-kinetic
simulations that correctly treat the transition from the continuum to the
rarefied region, we confirm that the energy-limited escape approximation is
valid when adiabatic expansion is the dominant cooling process. However, this
does not imply that the outflow goes sonic. In fact in the sonic regime, the
energy limited approximation can significantly under estimate the escape rate.
Rather large escape rates and concomitant adiabatic cooling can produce
atmospheres with subsonic flow that are highly extended. Since this affects the
heating rate of the upper atmosphere and the interaction with external fields
and plasmas, we give a criterion for estimating when the outflow goes transonic
in the continuum region. This is applied to early terrestrial atmospheres,
exoplanet atmospheres, and the atmosphere of the ex-planet, Pluto, all of which
have large escape rates. The paper and its erratum, combined here, are
published: ApJL 768, L4 (2013); ApJ, 779, L30 (2013).Comment: 11 pages, 3 figure
Carrier lifetimes in ion-damaged GaAs
Photoluminescence excitation correlation spectroscopy has been used to measure the dependence of carrier lifetime on the H+ ion implantation dose in GaAs. For doses greater than 1×10^12 cm^−2 the carrier lifetime is inversely proportional to the ion dose. The minimum lifetime measured was 0.6±0.2 ps for a dose of 1×10^14 cm^−2. Most important, there is no sign of saturation of carrier lifetime with ion dose down to this lifetime, thus still shorter lifetimes should be achievable with increased ion dose
An improved panel method for the solution of three-dimensional leading edge vortex flows Volume 2: User's guide and programmer's document
A computer program developed for solving the subsonic, three dimensional flow over wing-body configurations with leading edge vortex separation is presented. Instructions are given for the proper set up and input of a problem into the computer code. Program input formats and output are described, as well as the overlay structure of the program. The program is written in FORTRAN
User's manual: Subsonic/supersonic advanced panel pilot code
Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words
Combined inhibitory effect of nisin with EDTA against Listeria monocytogenes in soy-protein edible coating on turkey frankfurters stored at 4°C and 10°C
Several food contamination outbreaks are linked to Listeria monocytogenes. More effective methods are needed to prevent the growth and recontamination of L. monocytogenes on ready-to-eat (RTE) food products. Therefore, the objectives of this study were to evaluate the inhibitory activities of nisin (10,000 IU/mL), EDTA (sodium Ethylenediaminetetraacetic acid: 1.6 mg/mL), and the combination of nisin (10,000 IU/mL) with EDTA 1.6 mg/mL either in brain-heart-infusion (BHI) media at 37°C for 72 h or in soy-protein edible coating on the surface of full-fat commercial turkey frankfurters against the cell populations of approximately 106 colony forming units (CFU/mL) of L. monocytogenes. The surface-inoculated frankfurters were dipped into soy-protein film forming solutions with and without the addition of antimicrobial agents [(nisin (10,000 IU) or EDTA (0.16%) or the combination)] and stored at either 4°C or 10°C. The inhibitory effects of edible coatings were evaluated on a weekly basis for 45 d. The greatest inhibitory activities of 6 log cycle reductions of L. monocytogenes were found when nisin was combined with EDTA and eliminated 6 log cycles of L. monocytogenes in both systems. In the combined nisin (10,000 IU) with EDTA (0.16%) treatment, the L. monocytogenes population was reduced to undetectable levels after 15 h or 7 d incubation in BHI at 37°C or on turkey frankfurters stored at 4°C and 10°C, respectively. This research has demonstrated that the use of an edible film coating containing nisin with EDTA is a promising means of controlling the growth and recontamination of L. monocytogenes on RTE meat products
An improved panel method for the solution of three-dimensional leading-edge vortex flows. Volume 1: Theory document
An improved panel method for the solution of three dimensional flow and wing and wing-body combinations with leading edge vortex separation is presented. The method employs a three dimensional inviscid flow model in which the configuration, the rolled-up vortex sheets, and the wake are represented by quadratic doublet distributions. The strength of the singularity distribution as well as shape and position of the vortex spirals are computed in an iterative fashion starting with an assumed initial sheet geometry. The method calculates forces and moments as well as detail surface pressure distributions. Improvements include the implementation of improved panel numerics for the purpose of elimination the highly nonlinear effects of ring vortices around double panel edges, and the development of a least squares procedure for damping vortex sheet geometry update instabilities. A complete description of the method is included. A variety of cases generated by the computer program implementing the method are presented which verify the mathematical assumptions of the method and which compare computed results with experimental data to verify the underlying physical assumptions made by the method
Combining remotely sensed and other measurements for hydrologic areal averages
A method is described for combining measurements of hydrologic variables of various sampling geometries and measurement accuracies to produce an estimated mean areal value over a watershed and a measure of the accuracy of the mean areal value. The method provides a means to integrate measurements from conventional hydrological networks and remote sensing. The resulting areal averages can be used to enhance a wide variety of hydrological applications including basin modeling. The correlation area method assigns weights to each available measurement (point, line, or areal) based on the area of the basin most accurately represented by the measurement. The statistical characteristics of the accuracy of the various measurement technologies and of the random fields of the hydrologic variables used in the study (water equivalent of the snow cover and soil moisture) required to implement the method are discussed
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