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For linearly constrained least-squares problems that depend on a vector of parameters, this paper proposes techniques for reducing the number of involved optimization variables. After first eliminating equality constraints in a numerically…

Optimization and Control · Mathematics 2020-12-21 Alberto Bemporad , Gionata Cimini

Variational Quantum Algorithms (VQAs) are relatively robust to noise, but errors are still a significant detriment to VQAs on near-term quantum machines. It is imperative to employ error mitigation techniques to improve VQA fidelity. While…

We consider constrained optimization problems with a nonsmooth objective function in the form of mathematical expectation. The Sample Average Approximation (SAA) is used to estimate the objective function and variable sample size strategy…

Optimization and Control · Mathematics 2022-08-09 Natasa Krejic , Natasa Krklec Jerinkic , Tijana Ostojic

Sparse coding refers to the pursuit of the sparsest representation of a signal in a typically overcomplete dictionary. From a Bayesian perspective, sparse coding provides a Maximum a Posteriori (MAP) estimate of the unknown vector under a…

Signal Processing · Electrical Eng. & Systems 2019-09-04 Dror Simon , Jeremias Sulam , Yaniv Romano , Yue M. Lu , Michael Elad

Sparse and convolutional constraints form a natural prior for many optimization problems that arise from physical processes. Detecting motifs in speech and musical passages, super-resolving images, compressing videos, and reconstructing…

Computer Vision and Pattern Recognition · Computer Science 2014-06-11 Hilton Bristow , Simon Lucey

The phase retrieval problem is a fundamental problem in many fields, which is appealing for investigation. It is to recover the signal vector $\tilde{x}\in\mathbb{C}^d$ from a set of $N$ measurements $b_n=|f^*_n\tilde{x}|^2,\ n=1,\cdots,…

Optimization and Control · Mathematics 2017-08-30 Jian-Feng Cai , Haixia Liu , Yang Wang

A non-iterative phase noise compensation method based on the sum-product algorithm (SPA) is applied to the outputs of intersymbol interference (ISI) channels. The outputs are modeled as independent Gaussian random variables, and the…

Information Theory · Computer Science 2026-04-21 Alex Jäger , Gerhard Kramer

Principal component analysis (PCA) is often used to reduce the dimension of data by selecting a few orthonormal vectors that explain most of the variance structure of the data. L1 PCA uses the L1 norm to measure error, whereas the…

Machine Learning · Statistics 2020-09-04 Young Woong Park , Diego Klabjan

Current approaches to fault-tolerant quantum computation will not enable useful quantum computation on near-term devices of 50 to 100 qubits. Leading proposals, such as the color code and surface code schemes, must devote a large fraction…

Quantum Physics · Physics 2017-11-08 Peter D. Johnson , Jonathan Romero , Jonathan Olson , Yudong Cao , Alán Aspuru-Guzik

In recent years Variation Autoencoders have become one of the most popular unsupervised learning of complicated distributions.Variational Autoencoder (VAE) provides more efficient reconstructive performance over a traditional autoencoder.…

Machine Learning · Statistics 2017-07-12 Gautam Ramachandra

This work presents a new variation of the commonly used Least Mean Squares Algorithm (LMS) for the identification of sparse signals with an a-priori known sparsity using a hard threshold operator in every iteration. It examines some useful…

Systems and Control · Computer Science 2016-08-04 Lampros Flokas , Petros Maragos

This article presents a comparative study of three different types of estimators used for supervised linear unmixing of two MEx/OMEGA hyperspectral cubes. The algorithms take into account the constraints of the abundance fractions, in order…

Instrumentation and Methods for Astrophysics · Physics 2011-12-19 Konstantinos E. Themelis , Frédéric Schmidt , Olga Sykioti , Athanasios A. Rontogiannis , Konstantinos D. Koutroumbas , Ioannis A. Daglis

We describe a new multi-scale deconvolution algorithm that can also be used in multi-frequency mode. The algorithm only affects the minor clean loop. In single-frequency mode, the minor loop of our improved multi-scale algorithm is over an…

Instrumentation and Methods for Astrophysics · Physics 2017-08-02 A. R. Offringa , O. Smirnov

Scanning Electron Microscopy (SEM) images often suffer from noise contamination, which degrades image quality and affects further analysis. This research presents a complete approach to estimate their Signal-to-Noise Ratio (SNR) and noise…

Machine Learning · Computer Science 2025-10-10 D. Chee Yong Ong , I. Bukhori , K. S. Sim , K. Beng Gan

Least squares approximation is a technique to find an approximate solution to a system of linear equations that has no exact solution. In a typical setting, one lets $n$ be the number of constraints and $d$ be the number of variables, with…

Data Structures and Algorithms · Computer Science 2010-09-28 Petros Drineas , Michael W. Mahoney , S. Muthukrishnan , Tamas Sarlos

We present a new Unbiased Minimal Variance (UMV) estimator for the purpose of reconstructing the large--scale structure of the universe from noisy, sparse and incomplete data. Similar to the Wiener Filter (WF), the UMV estimator is derived…

Astrophysics · Physics 2009-10-31 Saleem Zaroubi

Blind methods often separate or identify signals or signal subspaces up to an unknown scaling factor. Sometimes it is necessary to cope with the scaling ambiguity, which can be done through reconstructing signals as they are received by…

Sound · Computer Science 2017-08-02 Zbyněk Koldovský , Francesco Nesta

One of the main limitations of utilizing optimal wavefront shaping in imaging and authentication applications is the slow speed of the optimization algorithms currently being used. To address this problem we develop a micro-genetic…

Processing quantum information on continuous variables requires a highly nonlinear element in order to attain universality. Noise reduction in processing such quantum information involves the use of a nonlinear phase state as a non-Gaussian…

Quantum Physics · Physics 2019-11-27 Darren W. Moore , Andrey A. Rakhubovsky , Radim Filip

We propose a novel scheme for laser phase noise measurements with minimized sensitivity to external fluctuations including interferometer vibration, temperature instability, other low-frequency noise, and relative intensity noise. In order…