6,481 research outputs found
The dish-Rankine SCSTPE program (Engineering Experiment no. 1)
Activities planned for phase 2 Of the Small Community Solar Thermal Power Experiment (PFDR) program are summarized with emphasis on a dish-Rankine point focusing distributed receiver solar thermal electric system. Major design efforts include: (1) development of an advanced concept indirect-heated receiver;(2) development of hardware and software for a totally unmanned power plant control system; (3) implementation of a hybrid digital simulator which will validate plant operation prior to field testing; and (4) the acquisition of an efficient organic Rankine cycle power conversion unit. Preliminary performance analyses indicate that a mass-produced dish-Rankine PFDR system is potentially capable of producing electricity at a levelized busbar energy cost of 60 to 70 mills per KWh and with a capital cost of about $1300 per KW
Generally covariant theories: the Noether obstruction for realizing certain space-time diffeomorphisms in phase space
Relying on known results of the Noether theory of symmetries extended to
constrained systems, it is shown that there exists an obstruction that prevents
certain tangent-space diffeomorphisms to be projectable to phase-space, for
generally covariant theories. This main result throws new light on the old fact
that the algebra of gauge generators in the phase space of General Relativity,
or other generally covariant theories, only closes as a soft algebra and not a
a Lie algebra.
The deep relationship between these two issues is clarified. In particular,
we see that the second one may be understood as a side effect of the procedure
to solve the first. It is explicitly shown how the adoption of specific
metric-dependent diffeomorphisms, as a way to achieve projectability, causes
the algebra of gauge generators (constraints) in phase space not to be a Lie
algebra --with structure constants-- but a soft algebra --with structure {\it
functions}.Comment: 22 pages, version to be published in Classical & Quantum Gravit
Tex2Shape: Detailed Full Human Body Geometry From a Single Image
We present a simple yet effective method to infer detailed full human body shape from only a single photograph. Our model can infer full-body shape including face, hair, and clothing including wrinkles at interactive frame-rates. Results feature details even on parts that are occluded in the input image. Our main idea is to turn shape regression into an aligned image-to-image translation problem. The input to our method is a partial texture map of the visible region obtained from off-the-shelf methods. From a partial texture, we estimate detailed normal and vector displacement maps, which can be applied to a low-resolution smooth body model to add detail and clothing. Despite being trained purely with synthetic data, our model generalizes well to real-world photographs. Numerous results demonstrate the versatility and robustness of our method
BV analysis for covariant and non-covariant actions
The equivalence between the covariant and the non-covariant version of a
constrained system is shown to hold after quantization in the framework of the
field-antifield formalism. Our study covers the cases of Electromagnetism and
Yang-Mills fields and sheds light on some aspects of the Faddeev-Popov method,
for both the coratiant and non-covariant approaches, which had not been fully
clarified in the literature.Comment: 21 pages, preprint # UTTG-02-93, UB-ECM-PF 93/5. To appear in Phys.
Rev.
Proceedings of the 2nd Iberian Nuclear Astrophysics Meeting on Compact Stars
This volume contains most of the links to the presentations delivered at this
international workshop. This meeting was the second in the series following the
previous I Encuentro Ib\'erico de Compstar, held at the University of Coimbra,
Portugal in 2010. The main purpose of this meeting was to strengthen the
scientific collaboration between the participants of the Iberian and the rest
of the southern European branches of the European Nuclear Astrophysics network,
formerly, COMPSTAR. This ESF (European Science Foundation) supported network
has been crucial in helping to make a broader audience for the the most
interesting and relevant research lines being developed currently in Nuclear
Astrophysics, especially related to the physics of neutron stars. The program
of the meeting was tailored to theoretical descriptions of the physics of
neutron stars although some input from experimental observers and other
condensed matter and optics areas of interest was also included.Comment: Journal of Physics: Conference Series Volume 342 (2012), Proceedings
of the 2nd Iberian Nuclear Astrophysics Meeting on Compact Stars, 22-23
September 2011, Salamanca-Spain. Editors, M. A. Perez-Garcia, J. Pons and C.
Albertus Editor
Reparameterization invariants for anisotropic Bianchi I cosmology with a massless scalar source
Intrinsic time-dependent invariants are constructed for classical, flat,
homogeneous, anisotropic cosmology with a massless scalar material source.
Invariance under the time reparameterization-induced canonical symmetry group
is displayed explicitly.Comment: 28 pages, to appear in General Relativity and Gravitation.
Substantial revisions: added foundational overview section 2, chose new
intrinsic time variable, worked with dimensionless variables, added appendix
with comparison and criticism of other approache
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