The Time-Frequency and Time-Scale communities have recently developed an enormous number of overcomplete signal dictionaries -- wavelets, wavelet packets, cosine packets, wilson bases, chirplets, warped bases, and hyperbolic cross bases being a few examples. Basis Pursuit is a technique for decomposing a signal into an "optimal" superposition of dictionary elements. The optimization criterion is the l 1 norm of coefficients. The method has several advantages over Matching Pursuit and Best Ortho Basis, including super-resolution and stability. 1 Introduction Over the last five years or so, there has been an explosion of awareness of alternatives to traditional signal representations. Instead of just representing objects as superpositions of sinusoids (the traditional Fourier representation) we now have available alternate dictionaries -- signal representation schemes -- of which the Wavelets dictionary is only the most well-known. Wavelet dictionaries, Gabor dictionaries, Multi-scale...

. Many problems in engineering analysis and design can be cast as convex optimization problems, often nonlinear and nondifferentiable. We give a high-level description of recently developed interior-point methods for convex optimization, explain how problem structure can be exploited in these algorithms, and illustrate the general scheme with numerical experiments. To give a rough idea of the efficiencies obtained, we are able to solve convex optimization problems with over 1000 variables and 10000 constraints in around 10 minutes on a workstation. Keywords. Optimization, numerical methods, linear programming, optimal control, robust control, convex programming, interior-point methods, FIR filter design, conjugate gradients 1. INTRODUCTION Many problems in engineering analysis and design can be cast as convex optimization problems, i.e., min f 0 (x) s.t. f i (x) 0; i = 1; : : : ; L; where the functions f i are convex. It is widely known that such problems have desirable properties,...

Abstract. Many large-scale problems in dynamic and stochastic optimization can be modeled with extended linear-quadratic programming, which admits penalty terms and treats them through duality. In general the objective functions in such problems are only piecewise smooth and must be minimized or maximized relative to polyhedral sets of high dimensionality. This paper proposes a new class of numerical methods for “fully quadratic ” problems within this framework, which exhibit second-order nonsmoothness. These methods, combining the idea of finite-envelope representation with that of modified gradient projection, work with local structure in the primal and dual problems simultaneously, feeding information back and forth to trigger advantageous restarts. Versions resembling steepest descent methods and conjugate gradient methods are presented. When a positive threshold of ε-optimality is specified, both methods converge in a finite number of iterations. With threshold 0, it is shown under mild assumptions that the steepest descent version converges linearly, while the conjugate gradient version still has a finite termination property. The algorithms are designed to exploit features of primal and dual decomposability of the Lagrangian, which are typically available in a large-scale setting, and they are open to considerable parallelization. Key words. Extended linear-quadratic programming, large-scale numerical optimization, finite-envelope representation, gradient projection, primal-dual methods, steepest descent methods, conjugate gradient methods. AMS(MOS) subject classifications. 65K05, 65K10, 90C20 1. Introduction. A

QPOPT is a set of Fortran subroutines for minimizing a general quadratic function subject to linear constraints and simple upper and lower bounds. QPOPT may also be used for linear programming and for finding a feasible point for a set of linear equalities and inequalities. If the quadratic function is convex (i.e., the Hessian is positive definite or positive semidefinite), the solution obtained will be a global minimizer. If the quadratic is nonconvex (i.e., the Hessian is indefinite), the solution obtained will be a local minimizer or a dead-point. A two-phase active-set method is used. The first phase minimizes the sum of infeasibilities. The second phase minimizes the quadratic function within the feasible region, using a reduced Hessian to obtain search directions. The method is most efficient when many constraints or bounds are active at the solution. QPOPT is not intended for large sparse problems, but there is no fixed limit on problem size. The source code is suitable for all scientific machines with a Fortran 77

. In this paper, we give a variant of the Topkis-Veinott method for solving inequality constrained optimization problems. This method uses a linearly constrained positive semi-definite quadratic problem to generate a feasible descent direction at each iteration. Under mild assumptions, the algorithm is shown to be globally convergent in the sense that every accumulation point of the sequence generated by the algorithm is a Fritz-John point of the problem. We introduce a Fritz-John (FJ) function, an FJ1 strong second-order sufficiency condition (FJ1-SSOSC) and an FJ2 strong second-order sufficiency condition (FJ2-SSOSC), and then show, without any constraint qualification (CQ), that (i) if an FJ point z satisfies the FJ1-SSOSC, then there exists a neighborhood N(z) of z such that for any FJ point y 2 N(z) n fzg, f 0 (y) 6= f 0 (z), where f 0 is the objective function of the problem; (ii) if an FJ point z satisfies the FJ2-SSOSC, then z is a strict local minimum of the problem. The resu...

The time-optimal control of flexible structures is considered. We formulate the general time-optimal control problem for single-axis flexible structures, and analytical results are given for the number of control switches for the one-bending-mode case, with and without damping. When there is no damping, it is shown that the time optimal control generally has 3 switches and is an odd function of time about the second switch except in certain isolated cases where there is only 1 switch. With damping, it is shown that there is always more than 1 switch. A numerical method is presented for solving the time-optimal control for general linear systems, and solutions are presented for flexible structures with several flexible modes, revealing interesting trends of the time-optimal control switch times as the maneuver sizes and the frequencies and damping ratios of the flexible modes are varied. 1 Introduction In many applications, such as manipulators, disk-drive heads, or pointing systems, s...

During rapid thermal processing (RTP) of semiconductor wafers it is essential that the wafer temperature closely tracks a pre-specified temperature trajectory and that the temperature profile across the wafer is nearly uniform whenever the wafer is at high temperatures. This paper considers axisymmetric RTP systems with multiple independently-controllable lamps. In such systems the relative lamp power settings can be adjusted so that the lamps provide a range of distributions of power over the wafer; this is useful because the ideal distribution of incident energy varies according to processing conditions and changes substantially during a single process cycle. In this paper numerical techniques are given for finding lamp power settings to minimize temperature error across the wafer both during steady-state hold and during transients; these numerical techniques involve the formulation of the minimum temperature error problem as a linear programming problem. A heuristic scheme for near-optimal trajectory following is presented. Open-loop-plus-feedback control is proposed for RTP temperature control -- open-loop control allows precise trajectory planning and feedback prevents drift due to disturbances and modeling errors. All of the above ideas are demonstrated in simulation on a fictional system qualitatively similar in its behavior to some real RTP systems.

General methods for obtaining maximum likelihood estimates in exponential families are demonstrated using a constrained autologistic model for estimating relatedness from DNA fingerprint data. The novel features are the use of constrained optimization and two new algorithms for maximum likelihood estimation. The first, the "phase I " algorithm determines the support of the MLE in the closure of the exponential family (a distribution in the family conditioned on a face of the convex support of the natural statistic) when the MLE does not exist in the traditional sense (a point in the natural parameter space). The second, the maximum Monte Carlo likelihood algorithm uses the Metropolis algorithm or the Gibbs sampler to obtain estimates when exact calculation of the likelihood is not possible. Separate papers on each algorithm accompany

The reactor network synthesis problem involves determining the type, size, and interconnections of the reactor units, optimal concentration and temperature profiles, and the heat load requirements of the process. A general framework is presented for the synthesis of optimal chemical reactor networks via an optimization approach. The possible design alternatives are represented via a process superstructure which includes continuous stirred tank reactors and cross flow reactors along with mixers and splitters that connect the units. The superstructure is mathematically modeled using differential and algebraic constraints and the resulting problem is formulated as an optimal control problem. The solution methodology for addressing the optimal control formulation involves the application of a control parameterization approach where the selected control variables are discretized in terms of time invariant parameters. The dynamic system is decoupled from the optimization and solved as a func...

A second generation of the Particle Beam Optics Laboratory has been developed with an emphasis on applications to problems in accelerator optimization. The new version of the software incorporates several enhancements that significantly extend the capabilities of the first release of PBO Lab described at EPAC98. Several charged particle optics programs, including