Constituent quark models and pentaquark baryons

We discuss certain general features of the pentaquark picture for the theta, its 10bar_F partner, Xi_{3/2}, and possible heavy quark analogues. Models employing spin-dependent interactions based on either effective Goldstone boson exchange or effective color magnetic exchange are also used to shed light on possible corrections to the Jaffe-Wilczek and Karliner-Lipkin scenarios. Some model-dependent features of the pentaquark picture (splitting patterns and relative decay couplings) are also discussed in the context of these models.Comment: 4 pages. Prepared for the Proceedings of the 1st APS Topical Group on Hadronic Physics (GHP) meeting, FNAL, Oct. 24-26, 200

Modeling steel corrosion in concrete structures - part 2: A unified adaptive finite element model for simulation of steel corrosion

Recently, numerical methods that can reliably predict the service life of reinforced concrete structures have attracted increasing attention. In this, the second of two companion papers, relevant literature on numerical modeling of steel corrosion is first reviewed. Then, a unified and straight-forward algorithm that is capable of performing different types of steel corrosion modeling using a single scheme is presented, based on the new inverse relation relating the current density with potential for the cathodic reaction proposed in the companion paper. Besides being significantly more efficient computationally arising from the selective mesh refinement feature of adaptive finite element modeling, the proposed algorithm can also efficiently model complex geometries and incorporate parameters that vary over the domain.© 2010 by ESG

Modeling steel corrosion in concrete structures - part 1: A new inverse relation between current density and potential for the cathodic reaction

Corrosion of steel reinforcement can seriously compromise the service life of reinforced concrete structures. Hence, service life prediction and enhancement of concrete structures under corrosion attack are of significant importance. As a result, numerical methods that can reliably predict the service life of concrete structures have attracted increasing attention. In this, the first of two companion papers, a simple and significantly improved inverse relation relating the current density with potential for the cathodic reaction is proposed. This enables the current densities to be determined accurately from the measured potentials. Equally importantly, the proposed inverse relation also enables the efficient and straight-forward nonlinear algorithm for modeling of steel corrosion in concrete structures to be developed. Such an algorithm is presented in the companion paper of this. © 2010 by ES