3,867 research outputs found
Thermodynamic Properties of Rashba Spin-Orbit-Coupled Fermi Gas
We investigate the thermodynamic properties of a superfluid Fermi gas subject
to Rashba spin-orbit coupling and effective Zeeman field. We adopt a T-matrix
scheme that takes beyond-mean-field effects, which are important for strongly
interacting systems, into account. We focus on the calculation of two important
quantities: the superfluid transition temperature and the isothermal
compressibility. Our calculation shows very distinct influences of the
out-of-plane and the in-plane Zeeman fields on the Fermi gas. We also confirm
that the in-plane Zeeman field induces a Fulde-Ferrell superfluid below the
critical temperature and an exotic finite-momentum pseudo-gap phase above the
critical temperature.Comment: 8 pages, 9 figure
A Hybrid Model for Document Retrieval Systems.
A methodology for the design of document retrieval systems is presented. First, a composite index term weighting model is developed based on term frequency statistics, including document frequency, relative frequency within document and relative frequency within collection, which can be adjusted by selecting various coefficients to fit into different indexing environments. Then, a composite retrieval model is proposed to process a user\u27s information request in a weighted Phrase-Oriented Fixed-Level Expression (POFLE), which may apply more than Boolean operators, through two phases. That is, we have a search for documents which are topically relevant to the information request by means of a descriptor matching mechanism, which incorporate a partial matching facility based on a structurally-restricted relationship imposed by indexing model, and is more general than matching functions of the traditional Boolean model and vector space model, and then we have a ranking of these topically relevant documents, by means of two types of heuristic-based selection rules and a knowledge-based evaluation function, in descending order of a preference score which predicts the combined effect of user preference for quality, recency, fitness and reachability of documents
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