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The demand for fast solution of nonlinear optimization problems, coupled with the emergence of new concurrent computing architectures, drives the need for parallel algorithms to solve challenging nonlinear programming (NLP) problems. In this paper, we propose an augmented Lagrangian interior-point approach for general NLP problems that solves in parallel on a Graphics processing unit (GPU). The algorithm is iterative at three levels. The first level replaces the original problem by a sequence of bound-constrained optimization problems using an augmented Lagrangian method. Each of these bound-constrained problems is solved using a nonlinear interior-point method. Inside the interior-point method, the barrier sub-problems are solved using a variation of Newton's method, where the linear system is solved using a preconditioned conjugate gradient (PCG) method, which is implemented efficiently on a GPU in parallel. This algorithm shows an order of magnitude speedup on several test problems from the COPS test set.

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The Water Security Toolkit (WST) is a suite of open source software tools that can be used by water utilities to create response strategies to reduce the impact of contamination in a water distribution network. WST includes hydraulic and water quality modeling software, optimization methodologies, and visualization tools to identify: (1) sensor locations to detect contamination, (2) locations in the network in which the contamination was introduced, (3) hydrants to remove contaminated water from the distribution system, (4) locations in the network to inject decontamination agents to inactivate, remove, or destroy contaminants, (5) locations in the network to take grab samples to help identify the source of contamination and (6) valves to close in order to isolate contaminated areas of the network. This user manual describes the different components of WST, along with examples and case studies. License Notice The Water Security Toolkit (WST) v.1.2 Copyright c 2012 Sandia Corporation. Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive license for use of this work by or on behalf of the U.S. government. This software is distributed under the Revised BSD License (see below). In addition, WST leverages a variety of third-party software packages, which have separate licensing policies:

Cutter selection is a critical subtask of machining process planning. In this two-part series, we develop a robust approach for the selection of an optimal set of milling cutters for a 2.5D generalized pocket. In the first article (part 1), we present a solid modeling approach for the construction of the Voronoi mountain for the pocket geometry, which is a 3D extension of the Voronoi diagram. The major contributions of this work include: (1) the development of a robust and systematic procedure for construction of the Voronoi mountain for a multiply-connected curvilinear polygon; and (b) an extension of the Voronoi mountain concept to handle open edges.