1,108 research outputs found
Review of recent results in spin physics
Recent results in polarized DIS are reviewed. Particular emphasis is placed
on new measurements of transverse and longitudinal asymmetries, on the tests of
the spin sum rules and on the analysis of the spin structure function in
perturbative QCD at NLO.Comment: 15 pages, LaTex, 15 eps figures included, to be published in
Proceedings of 7th Int. Workshop on Deep Inelastic Scattering and QCD (DIS99
A Polarized HERA Collider
A brief review is given of the status of nucleon spin structure functions as
determined from polarized deep inelastic lepton-nucleon scatttering, including
current outstanding problems. The characteristics of a polarized HERA collider,
some of the particle physics topics it could address, and the accelerator
physics challenges it must meet are discussed.Comment: 5 Pages, 6 Figures, To be published in the Proceedings of the DIS99
Conference April 1999, DESY Zeuthen, German
A multi-objective optimisation model for a general polymer electrolyte membrane fuel cell system
This paper presents an optimisation model for a general polymer electrolyte membrane (PEM) fuel cell system Suitable for efficiency and size trade-offs investigation. Simulation of the model for a base case shows that for a given output power, a more efficient system is bigger and vice versa. Using the weighting method to perform a multi-objective optimisation, the Pareto sets were generated for different stack output powers. A Pareto set, presented as a plot of the optimal efficiency and area of the membrane electrode assembly (MEA), gives a quantitative description of the compromise between efficiency and size. Overall, our results indicate that, to make the most of the size-efficiency trade-off behaviour, the system must be operated at an efficiency of at least 40% but not more than 47%. Furthermore, the MEA area should be at least 3 cm(2) W-1 for the efficiency to be practically useful. Subject to the constraints imposed on the model, which are based on technical practicalities, a PEM fuel cell system such as the one presented in this work cannot operate at an efficiency above 54%. The results of this work, specifically the multi-objective model, will form a useful and practical basis for subsequent techno-economic studies for specific applications. (C) 2009 Elsevier B.V. All rights reserved
Flavor Singlet Axial Coupling of the Proton - An Updated Analysis
We present a combined analysis of SESAM and TxL data for the flavor singlet
axial coupling G_A^1 of the proton, which is very helpful to stabilize the
disconnected signals at small quark masses.
From connected and disconnected contributions we use the tadpole improved
renormalization constant Z_A and obtain G_A^1=0.21(12).Comment: 3 pages, contribution to LATTICE99 (matrix elements
Spin dependent structure function at small and small
Theoretical expectations concerning the low and low behaviour of
are summarized and compared with the recent SMC data.Comment: 4 pages, plain LATEX, 1 eps figure; contribution to 3rd UK
Phenomenology Workshop on HERA Physics, St. John's College, Durham, UK,
September 199
Polarized lepton nucleon scattering - summary of the experimental spin sessions at DIS 99
This paper summarizes the contributions to the experimental sessions on
polarized lepton nucleon scattering at the DIS 99 workshop. Results are
reported about the flavor decomposition of the quark polarization, a first
direct measurement of a positive gluon polarization, the observation of a
double-spin asymmetry in diffractive rho production, the polarization of lambda
hyperons, the observation of transverse single-spin asymmetries and the
measurement of the Gerasimov-Drell-Hearn sum rule. Prospects of future fixed
target and collider facilities are discussed.Comment: 8 pages, 5 figures, Proc. of the 7th Int. Workshop on Deep Inelastic
Scattering and QCD (DIS99), Zeuthen, Germany, April 19-23, 1999, to appear in
Nucl. Phys. B (Proc. Suppl.
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