245,327 research outputs found
Spin susceptibility of the superfluid He-B in aerogel
The temperature dependence of paramagnetic susceptibility of the superfluid
^{3}He-B in aerogel is found. Calculations have been performed for an arbitrary
phase shift of s-wave scattering in the framework of BCS weak coupling theory
and the simplest model of aerogel as an aggregate of homogeneously distributed
ordinary impurities. Both limiting cases of the Born and unitary scattering can
be easily obtained from the general result. The existence of gapless
superfluidity starting at the critical impurity concentration depending on the
value of the scattering phase has been demonstrated. While larger than in the
bulk liquid the calculated susceptibility of the B-phase in aerogel proves to
be conspicuously smaller than that determined experimentally in the high
pressure region.Comment: 10 pages, 4 figures, REVTe
A Model for Multi-property Galaxy Cluster Statistics
The massive dark matter halos that host groups and clusters of galaxies have
observable properties that appear to be log-normally distributed about
power-law mean scaling relations in halo mass. Coupling this assumption with
either quadratic or cubic approximations to the mass function in log space, we
derive closed-form expressions for the space density of halos as a function of
multiple observables as well as forms for the low-order moments of properties
of observable-selected samples. Using a Tinker mass function in a {\Lambda}CDM
cosmology, we show that the cubic analytic model reproduces results obtained
from direct, numerical convolution at the 10 percent level or better over
nearly the full range of observables covered by current observations and for
redshifts extending to z = 1.5. The model provides an efficient framework for
estimating effects arising from selection and covariance among observable
properties in survey samples.Comment: 9 pages, 4 figures, uses on-line mass function calculator
http://hmf.icrar.org/. Submitted to MNRA
Research on multi-timescale operation optimization of a distributed electro-hydrogen coupling system considering grid interaction
Against the backdrop of increasingly prominent environmental issues, new energy consumption issues, and energy supply and demand balance issues, the optimization of multi time scale operation of distributed electro hydrogen coupling systems has become a research focus. Based on this, this article optimizes the multi time scale operation of a distributed electric hydrogen coupling system that takes into account grid interaction. By designing a system framework for distributed electro hydrogen coupling systems, operational strategies for each system were proposed. Analyzed the uncertainty and response characteristics of wind and solar power generation units and load demand, and constructed a multiple uncertainty model for distributed electric hydrogen coupling system. At the same time, a three stage, multi time scale operation optimization model of the electric hydrogen coupling system was constructed based on the response characteristics of the distributed electric hydrogen coupling system. The construction of these models reduced scheduling costs by 12.55% and increased clean energy consumption rate by 13.50%
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