Consider the inverse diffraction problem to determine a two-dimensional periodic structure from scattered elastic waves measured above the structure. We formulate the inverse problem as a least squares optimization problem, following the two-step algorithm by G. Bruckner and J. Elschner (2003 Inverse Problems 19 315-329) for electromagnetic diffraction gratings. Such a method is based on the Ki...

Many problems in machine learning and statistics can be formulated as (generalized) eigenproblems. In terms of the associated optimization problem, computing linear eigenvectors amounts to finding critical points of a quadratic function subject to quadratic constraints. In this paper we show that a certain class of constrained optimization problems with nonquadratic objective and constraints ca...

Inverse problems are ill-posed: the error function has its minimum in a flat elongated valley or surrounded by many local minima. Local optimization methods give unpredictable results if no prior information is available. Traditionally this has generated mistrust for the use of inverse methods. Stochastic approaches to inverse problems consists in shift attention to the probability of existence...

Problem statement: Underactuated finger mechanism is beneficial in the anthropomorphic applications in which it reduces the finger size, weight and power consumption due to the less number of actuators compared to its number of Degree Of Freedom (DOF). However, the currently existing underactuated finger is limited to grasping operations only and unable to pinch with the finger tip. Moreover, t...

PURPOSE Brachytherapy is a vital part of treating locally advanced cervix cancer. Point-based 2D treatment planning is conventionally used. New CT/MRI-compatible applicators for HDR brachytherapy make 3D conformal planning possible. GEC-ESTRO endorsed the EMBRACE (intErnational study on MRI-guided BRachytherapy in locally Advanced CErvical cancer) protocol which recommends standard-plan-based m...

This paper presents a new way to solve the inverse problem of electrocardiography in terms of heart model parameters. The developed event estimation and recognition method is based on an optimization system of heart model parameters. An ANN-based preliminary ECG analyser system has been created to reduce the searching space of the optimization algorithm. The optimal model parameters were determ...

This paper considers the following inverse optimization problem: given a linear program, a desired optimal objective value, and a set of feasible cost vectors, determine a cost vector such that the corresponding optimal objective value of the linear program is closest to the desired value. The above problem, referred here as the inverse optimal value problem, is significantly different from sta...

Despite advances in the domain of source coding, little recent work has been devoted to the problem of joint coding and decoding. In particular, the design of decoders has been, to our knowledge, little investigated. In this paper, we focus on image decoding and propose sufficient conditions on the design of the decoder, involving a priori assumptions on the solution and knowledge of the coder ...

The particle size distribution plays an important role in environmental pollution detection and human health protection, such as fog, haze, and soot. In this study, the attractive and repulsive particle swarm optimization algorithm and the basic particle swarm optimization were applied to retrieve the particle size distribution. The spectral extinction technique coupled with the anomalous diffr...

Global optimization methods including Particle Swarm Optimization are usually used to solve optimization problems when the number of parameters is small (hundreds). In the case of inverse problems the objective (or fitness) function used for sampling requires the solution of multiple forward solves. In inverse problems, both a large number of parameters, and very costly forward evaluations hamp...