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Iterative methods are proposed for certain augmented systems of linear equations that arise in interior methods for general nonlinear optimization. Interior methods define a sequence of KKT equations that represent the symmetrized (but indefinite) equations associated with New-ton's method for a point satisfying the perturbed optimality conditions. These(More)
We consider the problem of finding an approximate minimizer of a general quadratic function subject to a two-norm constraint. The Steihaug-Toint method minimizes the quadratic over a sequence of expanding subspaces until the iterates either converge to an interior point or cross the constraint boundary. The benefit of this approach is that an approximate(More)
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—Measurements of the magnetoquasistatic fields generated from a magnetic dipole (an electrically small current loop) located above the earth are presented and compared with calculations using complex image theory. With a horizontal (i.e., the surface normal parallel to the earth) emitting loop located at a height of h and a copolarized horizontal receiving(More)
Optimization for complex systems in engineering often involves the use of expensive computer simulation. By combining statistical emulation using treed Gaussian processes with pattern search optimization, we are able to perform robust local optimization more efficiently and effectively than using either method alone. Our approach is based on the(More)
We describe an asynchronous parallel derivative-free algorithm for linearly constrained optimization. Generating set search (GSS) is the basis of our method. At each iteration , a GSS algorithm computes a set of search directions and corresponding trial points and then evaluates the objective function value at each trial point. Asynchronous versions of the(More)
— High-frequency backscatter radio systems operate in the dyadic backscatter channel, a pinhole channel whose envelope probability density function and bit-error-rate performance are strongly affected by link envelope correlation – the envelope correlation between the forward and backscatter links of the dyadic backscatter channel. This paper shows that(More)
We consider the problem of how to group information when multiple similarities are known. For a group of people, we may know their education, geographic location and family connections and want to cluster the people by treating all three of these similarities simultaneously. Our approach is to store each similarity as a slice in a tensor. The similarity(More)