17,420 research outputs found
Frequency Restoration Reserve Control Scheme with Participation of Industrial Loads
In order to accommodate larger amounts of renewable energy resources, whose power output is inherently unpredictable, there is an increasing need for frequency control power reserves. Loads are already used to provide replacement reserves, i.e. the slowest kind of reserves, in several power systems. This paper proposes a control scheme for frequency restoration reserves with participation of industrial loads. Frequency restoration reserves are required to change their active power within a time frame of tens of seconds to tens of minutes in response to a regulation signal. Industrial loads in many cases already have the capacity and capability to participate in this service. A mapping of their process constraints to power and energy demand is proposed in order to integrate industrial loads in existing control schemes. The proposed control scheme has been implemented in a 74-bus test system. Dynamic simulations show that industrial loads can be successfully integrated into the power system as frequency restoration reserves. © 2013 IEEE
Monitoring and management of power transmission dynamics in an industrial smart grid
This article is a position paper whose purpose is to give the context for presentations in a special session at PowerTech 2013. The special session is being proposed by the EU FP7 Real-Smart Consortium, a Marie Curie Industry-Academic Pathways and Partnerships project. The paper gives an overview of topics on modeling, monitoring and management of power transmission dynamics with participation from large industrial loads. © 2013 IEEE
Collective modes in multicomponent condensates with anisotropy
We report the effects of anisotropy in the confining potential on two
component Bose-Einstein condensates (TBECs) through the properties of the low
energy quasiparticle excitations. Starting from generalized Gross Pitaevskii
equation, we obtain the Bogoliubov de-Gennes (BdG) equation for TBECs using the
Hartree-Fock-Bogoliubov (HFB) theory. Based on this theory, we present the
influence of radial anisotropy on TBECs in the immiscible or the
phase-separated domain. In particular, the TBECs of Rb~-Rb and
Cs~-Rb TBECs are chosen as specific examples of the two possible
interface geometries, shell-structured and side by side, in the immiscible
domain. We also show that the dispersion relation for the TBEC shell-structured
interface has two branches, and anisotropy modifies the energy scale and
structure of the two branches.Comment: 9 pages, 13 figure
Bifurcations, stability, and mode evolution in segregated condensate mixtures
We present new features of low energy Bogoliubov quasiparticle excitations of
a two component Bose-Einstein condensate (TBEC) in quasi-2D geometry at zero
temperature using Hartree-Fock-Bogoliubov (HFB). We, in particular, consider
the TBECs of Cs~-Rb and Rb~-Rb, and show specific
features in the low energy excitation spectrum as a function of the interaction
strength. For Rb~-Rb TBEC, the appearance of a new zero energy
mode is observed. Whereas for Cs~-Rb TBEC we report a
bifurcation of the softened Kohn mode at the point of transition from miscible
to immiscible domain. The lower energy mode, after the bifurcation, goes soft
and becomes a new Goldstone mode of the system.Comment: The paper has 9 pages and 12 figure
Flux jumps, Second Magnetization Peak anomaly and the Peak Effect phenomenon in single crystals of and
We present magnetization measurements in single crystals of the tetragonal
compound, which exhibit the phenomenon of peak effect as well as
the second magnetization peak anomaly for H 0.5T (H c). At the lower
field (50mT H 200mT), we have observed the presence of flux jumps,
which seem to relate to a structural change in the local symmetry of the flux
line lattice (a first order re-orientation transition across a local field in
some parts of the sample, in the range of 100mT to 150mT). These flux jumps are
also observed in a single crystal of for H c in the field
region from 2 mT to 25 mT, which are compatible with the occurrence of a
re-orientation transition at a lower field in a cleaner crystal of this
compound, as compared to those of . Vortex phase diagrams drawn for
H c in and show that the ordered elastic glass
phase spans a larger part of (H, T) space in the former as compared to latter,
thereby, reaffirming the difference in the relative purity of the two samples.Comment: 11 pages, 14 figure
Shear viscosity to entropy density ratio in nuclear multifragmentation
Nuclear multifragmentation in intermediate energy heavy ion collisions has
long been associated with liquid-gas phase transition. We calculate the shear
viscosity to entropy density ratio eta/s for an equilibrated system of nucleons
and fragments produced in multifragmentation within an extended statistical
multifragmentation model. The temperature dependence of eta/s exhibits
surprisingly similar behavior as that for water. In the coexistence phase of
fragments and light particles, the ratio eta/s reaches a minimum of comparable
depth as that for water in the vicinity of the critical temperature for
liquid-gas phase transition. The effects of freeze-out volume and surface
symmetry energy on eta/s in multifragmentation are studied.Comment: 5 pages, 5 figures, to appear in PR
Dietary Phytase: an ideal approach for a cost effective and low-polluting aquafeed
Global fishmeal production from wild-catch sources cannot continue to increase indefinitely; suitable alternatives have to be found for sustainable aquaculture. Plant-based aquafeed seems to be the ideal alternative to this, but has its own limitations. Plant ingredients are rich in phytic acid, which reduces the bioavailability of nutrients like minerals and protein to the fish, thereby causing aquaculture pollution. Dietary phytase treatment reduces the aquaculture pollution by improving the bioavailability of nutrients, and reduces the feed cost as evident from poultry and piggery. Phytase activity is highly dependent upon the pH of the gut. Unlike mammals, fish are either gastric or agastric, and hence, the action of dietary phytase varies from species to species. In this article, the authors attempt to summarise various effects of phytase on nutrient utilization, growth of fish and aquatic pollution
Magnetization in electron- and Mn- doped SrTiO3
Mn-doped SrTiO_3.0, when synthesized free of impurities, is a paramagnetic
insulator with interesting dielectric properties. Since delocalized charge
carriers are known to promote ferromagnetism in a large number of systems via
diverse mechanisms, we have looked for the possibility of any intrinsic,
spontaneous magnetization by simultaneous doping of Mn ions and electrons into
SrTiO_3 via oxygen vacancies, thereby forming SrTi_(1-x)Mn_xO_(3-d), to the
extent of making the doped system metallic. We find an absence of any
enhancement of the magnetization in the metallic sample when compared with a
similarly prepared Mn doped, however, insulating sample. Our results, thus, are
not in agreement with a recent observation of a weak ferromagnetism in metallic
Mn doped SrTiO_3 system.Comment: 10 pages and 4 figure
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