1,051,679 research outputs found
Separator for alkaline batteries
Separator compositions have been tested as components of three-plate silver-zinc oxide cells in a standard cycling test. Six materials meet imposed requirements, giving cycling performance superior to cellophane
Universality in the triton charge form factor
We consider the three-nucleon system within an effective theory with contact
interactions at leading order in the large scattering length. We calculate the
charge form factor of the triton at low momentum transfer and extract the
triton charge radius. At this order, no two-body currents contribute and the
calculation can be performed in the impulse approximation. We also comment on
the power counting for higher orders. The requirement of a three-body force for
renormalization of the three-nucleon system explains the previously observed
correlation between the triton binding energy and charge radius for different
model potentials.Comment: 11 pages, 2 eps figures, revtex4, version to appear in Nucl. Phys.
Surface-effect corrections for oscillation frequencies of evolved stars
Accurate modelling of solar-like oscillators requires that modelled mode
frequencies are corrected for the systematic shift caused by improper modelling
of the near-surface layers, known as the surface effect. ... We investigate how
much additional uncertainty is introduced to stellar model parameters by our
uncertainty about the functional form of the surface effect. At the same time,
we test whether any of the parametrizations is significantly better or worse at
modelling observed subgiants and low-luminosity red giants. We model six stars
observed by Kepler that show clear mixed modes. We fix the input physics of the
stellar models and vary the choice of surface correction ... Models using a
solar-calibrated power law correction consistently fit the observations more
poorly than the other four corrections. Models with the remaining four
corrections generally fit ... about equally well, with the combined surface
correction by Ball & Gizon perhaps being marginally superior. The fits broadly
agree on the model parameters within about the uncertainties, with
discrepancies between the modified Lorentzian and free power law corrections
occasionally exceeding the level. Relative to the best-fitting
values, the total uncertainties on the masses, radii and ages of the stars are
all less than 2, 1 and 6 per cent, respectively. A solar-calibrated power law
... appears unsuitable for use with more evolved solar-like oscillators. Among
the remaining surface corrections, the uncertainty in the model parameters
introduced by the surface effects is about twice as large as the uncertainty in
the individual fits for these six stars. Though the fits are thus somewhat less
certain because of our uncertainty of how to manage the surface effect, these
results also demonstrate that it is feasible to model the individual mode
frequencies of subgiants and low-luminosity red giants. ...Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 6
figures, 5 tables. Abstract slightly abridged to meet arXiv's 1920 character
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Melt viscosities of lattice polymers using a Kramers potential treatment
Kramers relaxation times and relaxation times and
for the end-to-end distances and for center of mass diffusion are
calculated for dense systems of athermal lattice chains. is defined
from the response of the radius of gyration to a Kramers potential which
approximately describes the effect of a stationary shear flow. It is shown that
within an intermediate range of chain lengths N the relaxation times
and exhibit the same scaling with N, suggesting that N-dependent
melt-viscosities for non-entangled chains can be obtained from the Kramers
equilibrium concept.Comment: submitted to: Journal of Chemical Physic
Solar cell mounting Patent
Fabrication of solar cell banks for attaching solar cells to base members or substrate
Chemisorption on a model bcc metal
The system considered here is that of a single atom with one energy level chemisorbed on the (001) surface of a model bcc metal. We present the change in the density of electronic states Δn (E) due to chemisorption for two cases: one when the adatom is bound to a single substrate atom in the "on‐site" configuration and the other when it is bound to four substrate atoms in the "centered fourfold site." In principle, this change in the density of states Δn can be related to the results of photoemission measurements
Statistical analysis of low level atmospheric turbulence
The statistical properties of low-level wind-turbulence data were obtained with the model 1080 total vector anemometer and the model 1296 dual split-film anemometer, both manufactured by Thermo Systems Incorporated. The data obtained from the above fast-response probes were compared with the results obtained from a pair of Gill propeller anemometers. The digitized time series representing the three velocity components and the temperature were each divided into a number of blocks, the length of which depended on the lowest frequency of interest and also on the storage capacity of the available computer. A moving-average and differencing high-pass filter was used to remove the trend and the low frequency components in the time series. The calculated results for each of the anemometers used are represented in graphical or tabulated form
Closed-loop two-echelon repairable item systems
In this paper we consider closed loop two-echelon repairable item systems with repair facilities both at a number of local service centers (called bases) and at a central location (the depot). The goal of the system is to maintain a number of production facilities (one at each base) in optimal operational condition. Each production facility consists of a number of identical machines which may fail incidentally. Each repair facility may be considered to be a multi-server station, while any transport from the depot to the bases is modeled as an ample server. At all bases as well as at the depot, ready-for-use spare parts (machines) are kept in stock. Once a machine in the production cell of a certain base fails, it is replaced by a ready-for-use machine from that base's stock, if available. The failed machine is either repaired at the base or repaired at the central repair facility. In the case of local repair, the machine is added to the local spare parts stock as a ready-for-use machine after repair. If a repair at the depot is needed, the base orders a machine from the central spare parts stock to replenish its local stock, while the failed machine is added to the central stock after repair. Orders are satisfied on a first-come-first-served basis while any requirement that cannot be satisfied immediately either at the bases or at the depot is backlogged. In case of a backlog at a certain base, that base's production cell performs worse. To determine the steady state probabilities of the system, we develop a slightly aggregated system model and propose a special near-product-form solution that provides excellent approximations of relevant performance measures. The depot repair shop is modeled as a server with state-dependent service rates, of which the parameters follow from an application of Norton's theorem for Closed Queuing Networks. A special adaptation to a general Multi-Class MDA algorithm is proposed, on which the approximations are based. All relevant performance measures can be calculated with errors which are generally less than one percent, when compared to simulation results. \u
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