Search Results for author: Justin Romberg

Found 36 papers, 5 papers with code

Subspace Tracking with Dynamical Models on the Grassmannian

no code implementations15 Feb 2024 Alex Saad-Falcon, Brighton Ancelin, Justin Romberg

Tracking signals in dynamic environments presents difficulties in both analysis and implementation.

Slepian Beamforming: Broadband Beamforming using Streaming Least Squares

no code implementations6 Dec 2023 Coleman DeLude, Mark A. Davenport, Justin Romberg

Alongside a careful discussion of this model and how to choose its parameters we show how to fit the model to new blocks of samples as they are received, producing a streaming output.

Decentralized and Privacy-Preserving Learning of Approximate Stackelberg Solutions in Energy Trading Games with Demand Response Aggregators

no code implementations4 Apr 2023 Styliani I. Kampezidou, Justin Romberg, Kyriakos G. Vamvoudakis, Dimitri N. Mavris

In this work, a novel Stackelberg game theoretic framework is proposed for trading energy bidirectionally between the demand-response (DR) aggregator and the prosumers.

energy trading Privacy Preserving

Iterative Broadband Source Localization

no code implementations21 Oct 2022 Coleman DeLude, Rakshith Sharma, Santhosh Karnik, Christopher Hood, Mark Davenport, Justin Romberg

We show that by using these models, our adapted algorithms can successfully localize broadband sources under a variety of adverse operating scenarios.

Loop Unrolled Shallow Equilibrium Regularizer (LUSER) -- A Memory-Efficient Inverse Problem Solver

no code implementations10 Oct 2022 Peimeng Guan, Jihui Jin, Justin Romberg, Mark A. Davenport

In inverse problems we aim to reconstruct some underlying signal of interest from potentially corrupted and often ill-posed measurements.

Computed Tomography (CT) Deblurring +2

Streaming Reconstruction from Non-uniform Samples

no code implementations2 Aug 2022 Justin Romberg

We present an online algorithm for reconstructing a signal from a set of non-uniform samples.

Broadband Beamforming via Linear Embedding

no code implementations14 Jun 2022 Coleman DeLude, Santhosh Karnik, Mark Davenport, Justin Romberg

In modern applications multi-sensor arrays are subject to an ever-present demand to accommodate signals with higher bandwidths.

Dimensionality Reduction

Finite-Time Complexity of Online Primal-Dual Natural Actor-Critic Algorithm for Constrained Markov Decision Processes

no code implementations21 Oct 2021 Sihan Zeng, Thinh T. Doan, Justin Romberg

To solve this constrained optimization program, we study an online actor-critic variant of a classic primal-dual method where the gradients of both the primal and dual functions are estimated using samples from a single trajectory generated by the underlying time-varying Markov processes.

A Two-Time-Scale Stochastic Optimization Framework with Applications in Control and Reinforcement Learning

no code implementations29 Sep 2021 Sihan Zeng, Thinh T. Doan, Justin Romberg

In our two-time-scale approach, one scale is to estimate the true gradient from these samples, which is then used to update the estimate of the optimal solution.

Reinforcement Learning (RL) Stochastic Optimization

Thomson's Multitaper Method Revisited

no code implementations22 Mar 2021 Santhosh Karnik, Justin Romberg, Mark A. Davenport

This is useful in problems where many samples are taken, and thus, using many tapers is desirable.

Finite Sample Analysis of Two-Time-Scale Natural Actor-Critic Algorithm

no code implementations26 Jan 2021 Sajad Khodadadian, Thinh T. Doan, Justin Romberg, Siva Theja Maguluri

In this paper, we characterize the \emph{global} convergence of an online natural actor-critic algorithm in the tabular setting using a single trajectory of samples.

Vocal Bursts Valence Prediction

Finite-Time Convergence Rates of Decentralized Stochastic Approximation with Applications in Multi-Agent and Multi-Task Learning

no code implementations28 Oct 2020 Sihan Zeng, Thinh T. Doan, Justin Romberg

We study a decentralized variant of stochastic approximation, a data-driven approach for finding the root of an operator under noisy measurements.

Multi-Task Learning Q-Learning +1

Fast Graph Attention Networks Using Effective Resistance Based Graph Sparsification

no code implementations15 Jun 2020 Rakshith S Srinivasa, Cao Xiao, Lucas Glass, Justin Romberg, Jimeng Sun

The attention mechanism has demonstrated superior performance for inference over nodes in graph neural networks (GNNs), however, they result in a high computational burden during both training and inference.

Graph Attention Node Classification

A Decentralized Policy Gradient Approach to Multi-task Reinforcement Learning

no code implementations8 Jun 2020 Sihan Zeng, Aqeel Anwar, Thinh Doan, Arijit Raychowdhury, Justin Romberg

We develop a mathematical framework for solving multi-task reinforcement learning (MTRL) problems based on a type of policy gradient method.

Atari Games Multi-Task Learning +3

Finite-Time Analysis of Stochastic Gradient Descent under Markov Randomness

no code implementations24 Mar 2020 Thinh T. Doan, Lam M. Nguyen, Nhan H. Pham, Justin Romberg

Motivated by broad applications in reinforcement learning and machine learning, this paper considers the popular stochastic gradient descent (SGD) when the gradients of the underlying objective function are sampled from Markov processes.

reinforcement-learning Reinforcement Learning (RL)

Localized sketching for matrix multiplication and ridge regression

no code implementations20 Mar 2020 Rakshith S Srinivasa, Mark A. Davenport, Justin Romberg

We consider sketched approximate matrix multiplication and ridge regression in the novel setting of localized sketching, where at any given point, only part of the data matrix is available.

regression

Decentralized sketching of low rank matrices

no code implementations NeurIPS 2019 Rakshith Sharma Srinivasa, Kiryung Lee, Marius Junge, Justin Romberg

We address a low-rank matrix recovery problem where each column of a rank-r matrix X of size (d1, d2) is compressed beyond the point of recovery to size L with L << d1.

Hardware-aware Pruning of DNNs using LFSR-Generated Pseudo-Random Indices

no code implementations9 Nov 2019 Foroozan Karimzadeh, Ningyuan Cao, Brian Crafton, Justin Romberg, Arijit Raychowdhury

Deep neural networks (DNNs) have been emerged as the state-of-the-art algorithms in broad range of applications.

Convex Programming for Estimation in Nonlinear Recurrent Models

no code implementations26 Aug 2019 Sohail Bahmani, Justin Romberg

We propose a formulation for nonlinear recurrent models that includes simple parametric models of recurrent neural networks as a special case.

Finite-Time Performance of Distributed Temporal Difference Learning with Linear Function Approximation

no code implementations25 Jul 2019 Thinh T. Doan, Siva Theja Maguluri, Justin Romberg

Our main contribution is to provide a finite-analysis on the performance of this distributed {\sf TD}$(\lambda)$ algorithm for both constant and time-varying step sizes.

Multi-agent Reinforcement Learning

Finite-Time Analysis of Distributed TD(0) with Linear Function Approximation for Multi-Agent Reinforcement Learning

no code implementations20 Feb 2019 Thinh T. Doan, Siva Theja Maguluri, Justin Romberg

In this problem, a group of agents works cooperatively to evaluate the value function for the global discounted accumulative reward problem, which is composed of local rewards observed by the agents.

Optimization and Control

Fast Compressive Sensing Recovery Using Generative Models with Structured Latent Variables

1 code implementation19 Feb 2019 Shaojie Xu, Sihan Zeng, Justin Romberg

Deep learning models have significantly improved the visual quality and accuracy on compressive sensing recovery.

Compressive Sensing

Appearance-based Gesture recognition in the compressed domain

no code implementations19 Feb 2019 Shaojie Xu, Anvesha Amaravati, Justin Romberg, Arijit Raychowdhury

We propose a novel appearance-based gesture recognition algorithm using compressed domain signal processing techniques.

Computational Efficiency Gesture Recognition

Fast Convex Pruning of Deep Neural Networks

1 code implementation17 Jun 2018 Alireza Aghasi, Afshin Abdi, Justin Romberg

We develop a fast, tractable technique called Net-Trim for simplifying a trained neural network.

Network Pruning

Solving Equations of Random Convex Functions via Anchored Regression

no code implementations17 Feb 2017 Sohail Bahmani, Justin Romberg

We consider the question of estimating a solution to a system of equations that involve convex nonlinearities, a problem that is common in machine learning and signal processing.

regression

Net-Trim: Convex Pruning of Deep Neural Networks with Performance Guarantee

1 code implementation NeurIPS 2017 Alireza Aghasi, Afshin Abdi, Nam Nguyen, Justin Romberg

This program seeks a sparse set of weights at each layer that keeps the layer inputs and outputs consistent with the originally trained model.

Phase Retrieval Meets Statistical Learning Theory: A Flexible Convex Relaxation

no code implementations13 Oct 2016 Sohail Bahmani, Justin Romberg

We propose a flexible convex relaxation for the phase retrieval problem that operates in the natural domain of the signal.

Learning Theory Retrieval

A Light-powered, Always-On, Smart Camera with Compressed Domain Gesture Detection

no code implementations26 May 2016 Anvesha A, Shaojie Xu, Ningyuan Cao, Justin Romberg, Arijit Raychowdhury

In this paper we propose an energy-efficient camera-based gesture recognition system powered by light energy for "always on" applications.

Dynamic Time Warping Gesture Recognition +1

Sweep Distortion Removal from THz Images via Blind Demodulation

no code implementations29 Mar 2016 Alireza Aghasi, Barmak Heshmat, Albert Redo-Sanchez, Justin Romberg, Ramesh Raskar

Heavy sweep distortion induced by alignments and inter-reflections of layers of a sample is a major burden in recovering 2D and 3D information in time resolved spectral imaging.

Denoising

Learning Shapes by Convex Composition

no code implementations23 Feb 2016 Alireza Aghasi, Justin Romberg

We present a mathematical and algorithmic scheme for learning the principal geometric elements in an image or 3D object.

Sparse Recovery of Streaming Signals Using L1-Homotopy

no code implementations14 Jun 2013 M. Salman Asif, Justin Romberg

In this paper, we discuss two such streaming systems and a homotopy-based algorithm for quickly solving the associated L1-norm minimization programs: 1) Recovery of a smooth, time-varying signal for which, instead of using block transforms, we use lapped orthogonal transforms for sparse representation.

Blind Deconvolution using Convex Programming

1 code implementation21 Nov 2012 Ali Ahmed, Benjamin Recht, Justin Romberg

That is, we show that if $\boldsymbol{x}$ is drawn from a random subspace of dimension $N$, and $\boldsymbol{w}$ is a vector in a subspace of dimension $K$ whose basis vectors are "spread out" in the frequency domain, then nuclear norm minimization recovers $\boldsymbol{w}\boldsymbol{x}^*$ without error.

Information Theory Information Theory

Dynamic Updating for L1 Minimization

2 code implementations9 Mar 2009 Muhammad Salman Asif, Justin Romberg

We consider cases where the underlying signal changes slightly between measurements, and where new measurements of a fixed signal are sequentially added to the system.

Information Theory Information Theory

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