Search Results for author: Stephen Becker

Found 33 papers, 12 papers with code

Optimization of Array Encoding for Ultrasound Imaging

no code implementations1 Mar 2024 Jacob Spainhour, Korben Smart, Stephen Becker, Nick Bottenus

Objective: The transmit encoding model for synthetic aperture imaging is a robust and flexible framework for understanding the effect of acoustic transmission on ultrasound image reconstruction.

Image Reconstruction

Variational Entropy Search for Adjusting Expected Improvement

no code implementations17 Feb 2024 Nuojin Cheng, Stephen Becker

Bayesian optimization is a widely used technique for optimizing black-box functions, with Expected Improvement (EI) being the most commonly utilized acquisition function in this domain.

Bayesian Optimization Variational Inference

Bi-fidelity Variational Auto-encoder for Uncertainty Quantification

1 code implementation25 May 2023 Nuojin Cheng, Osman Asif Malik, Subhayan De, Stephen Becker, Alireza Doostan

An effective algorithm is proposed to maximize the variational lower bound of the HF log-likelihood in the presence of limited HF data, resulting in the synthesis of HF realizations with a reduced computational cost.

Computational Efficiency Uncertainty Quantification

The Dependence of Parallel Imaging with Linear Predictability on the Undersampling Direction

no code implementations18 Jan 2023 Alex McManus, Stephen Becker, Nicholas Dwork

Parallel imaging with linear predictability takes advantage of information present in multiple receive coils to accurately reconstruct the image with fewer samples.

Image Reconstruction

QuadConv: Quadrature-Based Convolutions with Applications to Non-Uniform PDE Data Compression

2 code implementations9 Nov 2022 Kevin Doherty, Cooper Simpson, Stephen Becker, Alireza Doostan

We present a new convolution layer for deep learning architectures which we call QuadConv -- an approximation to continuous convolution via quadrature.

Data Compression

Superresolution photoacoustic tomography using random speckle illumination and second order moments

1 code implementation9 May 2021 Osman Asif Malik, Venkatalakshmi Vyjayanthi Narumanchi, Stephen Becker, Todd W. Murray

It is therefore much faster than the iterative method used by Idier et al. We also propose a new representation of the imaged object based on Dirac delta expansion functions.

Object

Stochastic Gradient Langevin Dynamics with Variance Reduction

no code implementations12 Feb 2021 Zhishen Huang, Stephen Becker

Stochastic gradient Langevin dynamics (SGLD) has gained the attention of optimization researchers due to its global optimization properties.

Modeling massive highly-multivariate nonstationary spatial data with the basis graphical lasso

no code implementations7 Jan 2021 Mitchell Krock, William Kleiber, Dorit Hammerling, Stephen Becker

The basis graphical lasso writes a univariate Gaussian process as a linear combination of basis functions weighted with entries of a Gaussian graphical vector whose graph is estimated from optimizing an $\ell_1$ penalized likelihood.

A Sampling-Based Method for Tensor Ring Decomposition

1 code implementation16 Oct 2020 Osman Asif Malik, Stephen Becker

We provide high-probability relative-error guarantees for the sampled least squares problems.

Numerical Analysis Numerical Analysis

Spectral estimation from simulations via sketching

no code implementations21 Jul 2020 Zhishen Huang, Stephen Becker

Sketching is a stochastic dimension reduction method that preserves geometric structures of data and has applications in high-dimensional regression, low rank approximation and graph sparsification.

Dimensionality Reduction regression

Locality-sensitive hashing in function spaces

no code implementations10 Feb 2020 Will Shand, Stephen Becker

We discuss the problem of performing similarity search over function spaces.

Guarantees for the Kronecker Fast Johnson-Lindenstrauss Transform Using a Coherence and Sampling Argument

1 code implementation19 Nov 2019 Osman Asif Malik, Stephen Becker

In the recent paper [Jin, Kolda & Ward, arXiv:1909. 04801], it is proved that the Kronecker fast Johnson-Lindenstrauss transform (KFJLT) is, in fact, a Johnson-Lindenstrauss transform, which had previously only been conjectured.

Numerical Analysis Numerical Analysis

Optimization and Learning with Information Streams: Time-varying Algorithms and Applications

no code implementations17 Oct 2019 Emiliano Dall'Anese, Andrea Simonetto, Stephen Becker, Liam Madden

Approaches for the design of time-varying or online first-order optimization methods are discussed, with emphasis on algorithms that can handle errors in the gradient, as may arise when the gradient is estimated.

Safe Feature Elimination for Non-Negativity Constrained Convex Optimization

no code implementations25 Jul 2019 James Folberth, Stephen Becker

Under reasonable conditions, our feature elimination strategy will eventually eliminate all zero features from the problem.

Randomization of Approximate Bilinear Computation for Matrix Multiplication

1 code implementation17 May 2019 Osman Asif Malik, Stephen Becker

We present a method for randomizing formulas for bilinear computation of matrix products.

Data Structures and Algorithms Numerical Analysis Numerical Analysis

One-Pass Sparsified Gaussian Mixtures

1 code implementation10 Mar 2019 Eric Kightley, Stephen Becker

We present a one-pass sparsified Gaussian mixture model (SGMM).

Clustering

Fast Randomized Matrix and Tensor Interpolative Decomposition Using CountSketch

1 code implementation29 Jan 2019 Osman Asif Malik, Stephen Becker

We propose a new fast randomized algorithm for interpolative decomposition of matrices which utilizes CountSketch.

Numerical Analysis Numerical Analysis 15-02

Perturbed Proximal Descent to Escape Saddle Points for Non-convex and Non-smooth Objective Functions

no code implementations24 Jan 2019 Zhishen Huang, Stephen Becker

We consider the problem of finding local minimizers in non-convex and non-smooth optimization.

Low-Rank Tucker Decomposition of Large Tensors Using TensorSketch

1 code implementation NeurIPS 2018 Osman Asif Malik, Stephen Becker

We propose two randomized algorithms for low-rank Tucker decomposition of tensors.

Efficient Solvers for Sparse Subspace Clustering

1 code implementation17 Apr 2018 Farhad Pourkamali-Anaraki, James Folberth, Stephen Becker

The $\ell_0$ model is non-convex but only needs memory linear in $n$, and is solved via orthogonal matching pursuit and cannot handle the case of affine subspaces.

Clustering

Improved Fixed-Rank Nyström Approximation via QR Decomposition: Practical and Theoretical Aspects

no code implementations8 Aug 2017 Farhad Pourkamali-Anaraki, Stephen Becker

The Nystrom method is a popular technique that uses a small number of landmark points to compute a fixed-rank approximation of large kernel matrices that arise in machine learning problems.

Randomized Clustered Nystrom for Large-Scale Kernel Machines

no code implementations20 Dec 2016 Farhad Pourkamali-Anaraki, Stephen Becker

Moreover, we introduce a randomized algorithm for generating landmark points that is scalable to large-scale data sets.

Clustering

A Randomized Approach to Efficient Kernel Clustering

no code implementations26 Aug 2016 Farhad Pourkamali-Anaraki, Stephen Becker

Kernel-based K-means clustering has gained popularity due to its simplicity and the power of its implicit non-linear representation of the data.

Clustering

Dual Smoothing and Level Set Techniques for Variational Matrix Decomposition

no code implementations1 Mar 2016 Aleksandr Y. Aravkin, Stephen Becker

We focus on the robust principal component analysis (RPCA) problem, and review a range of old and new convex formulations for the problem and its variants.

Preconditioned Data Sparsification for Big Data with Applications to PCA and K-means

2 code implementations31 Oct 2015 Farhad Pourkamali-Anaraki, Stephen Becker

We analyze a compression scheme for large data sets that randomly keeps a small percentage of the components of each data sample.

Robust Partially-Compressed Least-Squares

no code implementations16 Oct 2015 Stephen Becker, Ban Kawas, Marek Petrik, Karthikeyan N. Ramamurthy

While maintaining computational efficiency, our models provide robust solutions that are more accurate--relative to solutions of uncompressed least-squares--than those of classical compressed variants.

Computational Efficiency

Efficient Dictionary Learning via Very Sparse Random Projections

no code implementations5 Apr 2015 Farhad Pourkamali-Anaraki, Stephen Becker, Shannon M. Hughes

Performing signal processing tasks on compressive measurements of data has received great attention in recent years.

Clustering Dictionary Learning

QUIC & DIRTY: A Quadratic Approximation Approach for Dirty Statistical Models

no code implementations NeurIPS 2014 Cho-Jui Hsieh, Inderjit S. Dhillon, Pradeep K. Ravikumar, Stephen Becker, Peder A. Olsen

In this paper, we develop a family of algorithms for optimizing superposition-structured” or “dirty” statistical estimators for high-dimensional problems involving the minimization of the sum of a smooth loss function with a hybrid regularization.

Model Selection Multi-Task Learning +1

Time--Data Tradeoffs by Aggressive Smoothing

no code implementations NeurIPS 2014 John J. Bruer, Joel A. Tropp, Volkan Cevher, Stephen Becker

This paper proposes a tradeoff between sample complexity and computation time that applies to statistical estimators based on convex optimization.

Convex Optimization for Big Data

no code implementations4 Nov 2014 Volkan Cevher, Stephen Becker, Mark Schmidt

This article reviews recent advances in convex optimization algorithms for Big Data, which aim to reduce the computational, storage, and communications bottlenecks.

A variational approach to stable principal component pursuit

1 code implementation4 Jun 2014 Aleksandr Aravkin, Stephen Becker, Volkan Cevher, Peder Olsen

We introduce a new convex formulation for stable principal component pursuit (SPCP) to decompose noisy signals into low-rank and sparse representations.

Sparse projections onto the simplex

no code implementations7 Jun 2012 Anastasios Kyrillidis, Stephen Becker, Volkan Cevher and, Christoph Koch

Most learning methods with rank or sparsity constraints use convex relaxations, which lead to optimization with the nuclear norm or the $\ell_1$-norm.

Density Estimation

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