43 research outputs found
Analysis of Strong-Coupling Parameters for Superfluid 3He
Superfluid He experiments show strong deviation from the weak-coupling
limit of the Ginzburg-Landau theory, and this discrepancy grows with increasing
pressure. Strong-coupling contributions to the quasiparticle interactions are
known to account for this effect and they are manifest in the five
-coefficients of the fourth order Ginzburg-Landau free energy terms. The
Ginzburg-Landau free energy also has a coefficient to include magnetic
field coupling to the order parameter. From NMR susceptibility experiments, we
find the deviation of from its weak-coupling value to be negligible at
all pressures. New results for the pressure dependence of four different
combinations of -coefficients, _{345}, _{12},
_{245}, and _{5} are calculated and comparison is made with
theory.Comment: 6 pages, 2 figures, 1 table. Manuscript prepared for QFS200
Problem formulation for truth-table invariant cylindrical algebraic decomposition by incremental triangular decomposition
Cylindrical algebraic decompositions (CADs) are a key tool for solving problems in real algebraic geometry and beyond. We recently presented a new CAD algorithm combining two advances: truth-table invariance, making the CAD invariant with respect to the truth of logical formulae rather than the signs of polynomials; and CAD construction by regular chains technology, where first a complex decomposition is constructed by refining a tree incrementally by constraint. We here consider how best to formulate problems for input to this algorithm. We focus on a choice (not relevant for other CAD algorithms) about the order in which constraints are presented. We develop new heuristics to help make this choice and thus allow the best use of the algorithm in practice. We also consider other choices of problem formulation for CAD, as discussed in CICM 2013, revisiting these in the context of the new algorithm
A theorem proving framework for the formal verification of Web Services Composition
We present a rigorous framework for the composition of Web Services within a
higher order logic theorem prover. Our approach is based on the
proofs-as-processes paradigm that enables inference rules of Classical Linear
Logic (CLL) to be translated into pi-calculus processes. In this setting,
composition is achieved by representing available web services as CLL
sentences, proving the requested composite service as a conjecture, and then
extracting the constructed pi-calculus term from the proof. Our framework,
implemented in HOL Light, not only uses an expressive logic that allows us to
incorporate multiple Web Services properties in the composition process, but
also provides guarantees of soundness and correctness for the composition.Comment: In Proceedings WWV 2011, arXiv:1108.208
Infrared target and background radiometric measurements--concepts units and techniques
This report discusses concepts units and techniques for making and describing measurements of radiation from targets and backgrounds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32197/1/0000256.pd