Constraint handling in efficient global optimization
Real-world optimization problems are often subject to several constraints which are expensive to evaluate in terms of cost or time. Although a lot of effort is devoted to make use of surrogate models for expensive optimization tasks, not many strong surrogate-assisted algorithms can address the challenging constrained problems. Efficient Global Optimization (EGO) is a Kriging-based surrogate-assisted algorithm. It was originally proposed to address unconstrained problems and later was modified to solve constrained problems. However, these type of algorithms still suffer from several issues, mainly: (1) early stagnation, (2) problems with multiple active constraints and (3) frequent crashes.…
ElectromagneticN→N*(1535)transition in the relativistic constituent-quark model
We study a light-cone model of the nucleon and the ${S}_{11}(1535)$ resonance which provides a relativistic generalization of the constituent-quark model in the nonperturbative low-${Q}^{2}$ regime. The two parameters of the model, namely, the size parameter $\ensuremath{\alpha}$ and the constituent-quark mass ${m}_{q}\ensuremath{\approx}300$ MeV, are fixed by the axial form factor. We find good agreement for the electromagnetic form factors of the nucleon up to ${Q}^{2}\ensuremath{\approx}1\ensuremath{-}2$ Ge${\mathrm{V}}^{2}$. All static properties of the nucleon, except for the neutron charge radius, are reproduced within 10%. In addition, we show that the electromagnetic current of the …