26,844 research outputs found
Fourier-transform spectroscopy of Sr2 and revised ground state potential
Precise potentials for the ground state X1Sigma+g and the minimum region of
the excited state 2_1Sigma+u of Sr2 are derived by high resolution
Fourier-transform spectroscopy of fluorescence progressions from single
frequency laser excitation of Sr2 produced in a heat pipe at 950 Celsius. A
change of the rotational assignment by four units compared to an earlier work
(G. Gerber, R. M\"oller, and H. Schneider, J. Chem. Phys. 81, 1538 (1984)) is
needed for a consistent description leading to a significant shift of the
potentials towards longer inter atomic distances. The huge amount of ground
state data derived for the three different isotopomers 88Sr2, 86Sr88Sr and
87Sr88Sr (almost 60% of all excisting bound rovibrational ground state levels
for the isotopomer 88Sr2) fixes this assignment undoubtedly. The presented
ground state potential is derived from the observed transitions for the radial
region from 4 to 11 A (9 cm-1 below the asymptote) and is extended to the longe
range region by the use of theoretical dispersion coefficients together with
already available photoassociation data. New estimations of the scattering
lengths for the complete set of isotopic combinations are derived by mass
scaling with the derived potential. The data set for the excited state
2_1Sigma+u was sufficient to derive a potential energy curve around the
minimum.Comment: 10 pages, 7 figures, some small corrections done especially to the
potential description of the excited state (already included in the published
journal version
Internal versus External Capital Markets
This paper presents a framework for analyzing the costs and benefits of internal vs. external capital allocation. We focus primarily on comparing an internal capital market to bank lending. While both represent centralized forms of financing, in the former case the financing is owner-provided, while in the latter case it is not. We argue that the ownership aspect of internal capital allocation has three important consequences: 1) it leads to more monitoring than bank lending; 2) it reduces managers' entrepreneurial incentives; and 3) it makes it easier to efficiently redeploy the assets of projects that are performing poorly under existing management.
Using rewards and penalties to obtain desired subject performance
Operant conditioning procedures, specifically the use of negative reinforcement, in achieving stable learning behavior is described. The critical tracking test (CTT) a method of detecting human operator impairment was tested. A pass level is set for each subject, based on that subject's asymptotic skill level while sober. It is critical that complete training take place before the individualized pass level is set in order that the impairment can be detected. The results provide a more general basis for the application of reward/penalty structures in manual control research
The effects of alcohol on driver performance in a decision making situation
The results are reviewed of driving simulator and in-vehicle field test experiments of alcohol effects on driver risk taking. The objective was to investigate changes in risk taking under alcoholic intoxication and relate these changes to effects on traffic safety. The experiments involved complex 15 minute driving scenarios requiring decision making and steering and speed control throughout a series of typical driving situations. Monetary rewards and penalties were employed to simulate the real-world motivations inherent in driving. A full placebo experimental design was employed, and measures related to traffic safety, driver/vehicle performance and driver behavior were obtained. Alcohol impairment was found to increase the rate of accidents and speeding tickets. Behavioral measures showed these traffic safety effects to be due to impaired psychomotor performance and perceptual distortions. Subjective estimates of risk failed to show any change in the driver's willingness to take risks when intoxicated
Realistic Magnetohydrodynamical Simulation of Solar Local Supergranulation
Three-dimensional numerical simulations of solar surface magnetoconvection
using realistic model physics are conducted. The thermal structure of
convective motions into the upper radiative layers of the photosphere, the main
scales of convective cells and the penetration depths of convection are
investigated. We take part of the solar photosphere with size of 60x60 Mm in
horizontal direction and by depth 20 Mm from level of the visible solar
surface. We use a realistic initial model of the Sun and apply equation of
state and opacities of stellar matter. The equations of fully compressible
radiation magnetohydrodynamics with dynamical viscosity and gravity are solved.
We apply: 1) conservative TVD difference scheme for the magnetohydrodynamics,
2) the diffusion approximation for the radiative transfer, 3) dynamical
viscosity from subgrid scale modeling. In simulation we take uniform
two-dimesional grid in gorizontal plane and nonuniform grid in vertical
direction with number of cells 600x600x204. We use 512 processors with
distributed memory multiprocessors on supercomputer MVS-100k in the Joint
Computational Centre of the Russian Academy of Sciences.Comment: 6 pages, 5 figures, submitted to the proceedings of the GONG 2008 /
SOHO XXI conferenc
Online mechanism design for electric vehicle charging
The rapid increase in the popularity of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) is expected to place a considerable strain on the existing electricity grids, due to the high charging rates these vehicles require. In many places, the limited capacity of the local electricity distribution network will be exceeded if many such vehicles are plugged in and left to charge their batteries simultaneously. Thus, it will become increasingly important to schedule the charging of these vehicles, taking into account the vehicle owners’ preferences, and the local constraints on the network. In this paper, we address this setting using online mechanism design and develop a mechanism that incentivises agents (representing vehicle owners) to truthfully reveal their preferences, as well as when the vehicle is available for charging. Existing related online mechanisms assume that agent preferences can be described by a single parameter. However, this is not appropriate for our setting since agents are interested in acquiring multiple units of electricity and can have different preferences for these units, depending on factors such as their expected travel distance. To this end, we extend the state of the art in online mechanism design to multi-valued domains, where agents have non-increasing marginal valuations for each subsequent unit of electricity. Interestingly, we show that, in these domains, the mechanism occasionally requires leaving electricity unallocated to ensure truthfulness. We formally prove that the proposed mechanism is dominant-strategy incentive compatible, and furthermore, we empirically evaluate our mechanism using data from a real-world trial of electric vehicles in the UK. We show that our approach outperforms any fixed price mechanism in terms of allocation efficiency, while performing only slightly worse than a standard scheduling heuristic, which assumes non-strategic agents
On the Fourier transform of the characteristic functions of domains with -smooth boundary
We consider domains with -smooth boundary and
study the following question: when the Fourier transform of the
characteristic function belongs to ?Comment: added two references; added footnotes on pages 6 and 1
Coupling of Transport and Chemical Processes in Catalytic Combustion
Catalytic combustors have demonstrated the ability to operate efficiently over a much wider range of fuel air ratios than are imposed by the flammability limits of conventional combustors. Extensive commercial use however needs the following: (1) the design of a catalyst with low ignition temperature and high temperature stability, (2) reducing fatigue due to thermal stresses during transient operation, and (3) the development of mathematical models that can be used as design optimization tools to isolate promising operating ranges for the numerous operating parameters. The current program of research involves the development of a two dimensional transient catalytic combustion model and the development of a new catalyst with low temperature light-off and high temperature stablity characteristics
Superconducting atomic contacts under microwave irradiation
We have measured the effect of microwave irradiation on the dc
current-voltage characteristics of superconducting atomic contacts. The
interaction of the external field with the ac supercurrents leads to replicas
of the supercurrent peak, the well known Shapiro resonances. The observation of
supplementary fractional resonances for contacts containing highly transmitting
conduction channels reveals their non-sinusoidal current-phase relation. The
resonances sit on a background current which is itself deeply modified, as a
result of photon assisted multiple Andreev reflections. The results provide
firm support for the full quantum theory of transport between two
superconductors based on the concept of Andreev bound states
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