16,726 research outputs found
Determination of solid mass fraction in partially frozen hydrocarbon fuels
Filtration procedures alone are insufficient to determine the amounts of crystalline solid in a partially frozen hydrocarbon distillate fraction. This is due to the nature of the solidification process by which a large amount of liquid becomes entrapped within an interconnected crystalline structure. A technique has been developed to supplement filtration methods with an independent determination of the amount of liquid in the precipitate thereby revealing the actual value of mass percent crystalline solid, %S. A non-crystallizing dye is injected into the fuel and used as a tracer during the filtration. The relative concentrations of the dye in the filtrate and precipitate fractions is subsequently detected by a spectrophotometric comparison. The filtration apparatus was assembled so that the temperature of the sample is recorded immediately above the filter. Also, a second method of calculation has been established which allows significant reduction in test time while retaining acceptable accuracy of results. Data have been obtained for eight different kerosene range hydrocarbon fuels
Cloning, sequencing, and characterization of the hexahydro-1,3,5-trinitro-1,3,5-triazine degradation gene cluster from Rhodococcus rhodochrous
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xpLA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization
Rethinking project selection at the Monterey Bay Aquarium
The article of record as published may be found at https://www.jstor.org/stable/25062652In 1995, the Monterey Bay Aquarium started an experimental business unit called Electronic Outreach. Electronic Outreach's mission was to employ emerging technologies to deliver the aquarium's messages of ocean stewardship to diverse and scattered audiences. Faced with many projects from which to choose, the Electronic Outreach team wanted to determine which projects were most likely to succeed before they actually had to dedicate resources to development. We constructed two models to help them accomplish this: a multiattribute-value model to quantify a project's alignment with the aquarium's mission and a discounted-cash-flow model to quantify a project's viability as a business venture. We then combined the outputs of these two models into a two-dimensional frame work to allow the Electronic Outreach team members to focus on monetary-nonmonetary trade-offs when evaluating potential projects
Measurements of heavy ion beam losses from collimation
The collimation efficiency for Pb ion beams in the LHC is predicted to be
lower than requirements. Nuclear fragmentation and electromagnetic dissociation
in the primary collimators create fragments with a wide range of Z/A ratios,
which are not intercepted by the secondary collimators but lost where the
dispersion has grown sufficiently large. In this article we present
measurements and simulations of loss patterns generated by a prototype LHC
collimator in the CERN SPS. Measurements were performed at two different
energies and angles of the collimator. We also compare with proton loss maps
and find a qualitative difference between Pb ions and protons, with the maximum
loss rate observed at different places in the ring. This behavior was predicted
by simulations and provides a valuable benchmark of our understanding of ion
beam losses caused by collimation.Comment: 12 pages, 20 figure
Beyond the Death of Linear Response: 1/f optimal information transport
Non-ergodic renewal processes have recently been shown by several authors to
be insensitive to periodic perturbations, thereby apparently sanctioning the
death of linear response, a building block of nonequilibrium statistical
physics. We show that it is possible to go beyond the ``death of linear
response" and establish a permanent correlation between an external stimulus
and the response of a complex network generating non-ergodic renewal processes,
by taking as stimulus a similar non-ergodic process. The ideal condition of
1/f-noise corresponds to a singularity that is expected to be relevant in
several experimental conditions.Comment: 4 pages, 2 figures, 1 table, in press on Phys. Rev. Let
Forces on Bins - The Effect of Random Friction
In this note we re-examine the classic Janssen theory for stresses in bins,
including a randomness in the friction coefficient. The Janssen analysis relies
on assumptions not met in practice; for this reason, we numerically solve the
PDEs expressing balance of momentum in a bin, again including randomness in
friction.Comment: 11 pages, LaTeX, with 9 figures encoded, gzippe
Are critical finite-size scaling functions calculable from knowledge of an appropriate critical exponent?
Critical finite-size scaling functions for the order parameter distribution
of the two and three dimensional Ising model are investigated. Within a
recently introduced classification theory of phase transitions, the universal
part of the critical finite-size scaling functions has been derived by
employing a scaling limit that differs from the traditional finite-size scaling
limit. In this paper the analytical predictions are compared with Monte Carlo
simulations. We find good agreement between the analytical expression and the
simulation results. The agreement is consistent with the possibility that the
functional form of the critical finite-size scaling function for the order
parameter distribution is determined uniquely by only a few universal
parameters, most notably the equation of state exponent.Comment: 11 pages postscript, plus 2 separate postscript figures, all as
uuencoded gzipped tar file. To appear in J. Phys. A
Correlation function and generalized master equation of arbitrary age
We study a two-state statistical process with a non-Poisson distribution of
sojourn times. In accordance with earlier work, we find that this process is
characterized by aging and we study three different ways to define the
correlation function of arbitrary age of the corresponding dichotomous
fluctuation based respectively on the Generalized Master Equation formalism, on
a Liouville-like approach and on a trajectory perspective.Comment: 11 pages, 1figur
A parametric open circuit voltage model for lithium ion batteries
The financial support of EPSRC UK and Jaguar Land Rover Ltd is gratefully acknowledged.We present an open circuit voltage (OCV) model for lithium ion (Li-ion) cells, which can be parameterized by measurements of the OCV of positive and negative electrode half-cells and a full cell. No prior knowledge of physical parameters related to particular cell chemistries is required. The OCV of the full cell is calculated from two electrode sub-models, which are comprised of additive terms that represent the phase transitions of the active electrode materials. The model structure is flexible and can be applied to any Li-ion cell chemistry. The model can account for temperature dependence and voltage hysteresis of the OCV. Fitting the model to OCV data recorded from a Li-ion cell at 0°C, 10°C, 20°C, 30°C and 40°C yielded high accuracies with errors (RMS) of less than 5 mV. The model can be used to maintain the accuracy of dynamic Li-ion cell models in battery management systems by accounting for the effects of capacity fade on the OCV. Moreover, the model provides a means to separate the cell's OCV into its constituent electrode potentials, which allows the electrodes’ capacities to be tracked separately over time, providing an insight into prevalent degradation mechanisms acting on the individual electrodes.Publisher PDFPeer reviewe
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