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On the significance of polarization charge and isomagnetic surface in the interaction between conducting fluid and magnetic field
From the frozen-in field lines concept, a highly conducting fluid can move
freely along, but not traverse to, magnetic field lines. We discuss this topic
and find that in the study of the frozen-in field lines concept, the effects of
inductive and capacitive reactance have been omitted. When admitted, the
relationships among the motional electromotive field, the induced electric
field, the eddy electric current, and the magnetic field becomes clearer and
the frozen-in field line concept can be reconsidered. We emphasize the
importance of isomagnetic surfaces and polarization charges, and show
analytically that whether a conducting fluid can freely traverse magnetic field
lines or not depends solely on the magnetic gradient in the direction of fluid
motion. If a fluid does not change its density distribution and shape (can be
regarded as a quasi-rigid body), and as long as it is moving along an
isomagnetic surface, it can freely traverse magnetic field lines without any
magnetic resistance no matter how strong the magnetic field is. When our
analysis is applied, the origin of the magnetic field of sunspots can be
interpreted easily. In addition, we also present experimental results to
support our analysis.Comment: 12 pages, 12 figures, 4 table
Modular invariance for conformal full field algebras
Let V^L and V^R be simple vertex operator algebras satisfying certain natural
uniqueness-of-vacuum, complete reducibility and cofiniteness conditions and let
F be a conformal full field algebra over the tensor product of V^L and V^R. We
prove that the q_\tau-\bar{q_\tau}-traces (natural traces involving
q_\tau=e^{2\pi i\tau} and \bar{q_\tau}=\bar{e^{2\pi i\tau}}) of geometrically
modified genus-zero correlation functions for F are convergent in suitable
regions and can be extended to doubly periodic functions with periods 1 and
\tau. We obtain necessary and sufficient conditions for these functions to be
modular invariant. In the case that V^L=V^R and F is one of those constructed
by the authors in \cite{HK}, we prove that all these functions are modular
invariant.Comment: 54 page
Full field algebras
We solve the problem of constructing a genus-zero full conformal field theory
(a conformal field theory on genus-zero Riemann surfaces containing both chiral
and antichiral parts) from representations of a simple vertex operator algebra
satisfying certain natural finiteness and reductive conditions. We introduce a
notion of full field algebra which is essentially an algebraic formulation of
the notion of genus-zero full conformal field theory. For two vertex operator
algebras, their tensor product is naturally a full field algebra and we
introduce a notion of full field algebra over such a tensor product. We study
the structure of full field algebras over such a tensor product using modules
and intertwining operators for the two vertex operator algebras. For a simple
vertex operator algebra V satisfying certain natural finiteness and reductive
conditions needed for the Verlinde conjecture to hold, we construct a bilinear
form on the space of intertwining operators for V and prove the nondegeneracy
and other basic properties of this form. The proof of the nondegenracy of the
bilinear form depends not only on the theory of intertwining operator algebras
but also on the modular invariance for intertwining operator algebras through
the use of the results obtained in the proof of the Verlinde conjecture by the
first author. Using this nondegenerate bilinear form, we construct a full field
algebra over the tensor product of two copies of V and an invariant bilinear
form on this algebra.Comment: 66 pages. One reference is added, a minor mistake on the invariance
under \sigma_{23} of the bilinear form on the space of intertwining operators
is corrected and some misprints are fixe
A Discriminatively Learned CNN Embedding for Person Re-identification
We revisit two popular convolutional neural networks (CNN) in person
re-identification (re-ID), i.e, verification and classification models. The two
models have their respective advantages and limitations due to different loss
functions. In this paper, we shed light on how to combine the two models to
learn more discriminative pedestrian descriptors. Specifically, we propose a
new siamese network that simultaneously computes identification loss and
verification loss. Given a pair of training images, the network predicts the
identities of the two images and whether they belong to the same identity. Our
network learns a discriminative embedding and a similarity measurement at the
same time, thus making full usage of the annotations. Albeit simple, the
learned embedding improves the state-of-the-art performance on two public
person re-ID benchmarks. Further, we show our architecture can also be applied
in image retrieval
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