Search Results for author: Ali Siahkoohi

Found 26 papers, 16 papers with code

InvertibleNetworks.jl: A Julia package for scalable normalizing flows

no code implementations20 Dec 2023 Rafael Orozco, Philipp Witte, Mathias Louboutin, Ali Siahkoohi, Gabrio Rizzuti, Bas Peters, Felix J. Herrmann

InvertibleNetworks. jl is a Julia package designed for the scalable implementation of normalizing flows, a method for density estimation and sampling in high-dimensional distributions.

Density Estimation Seismic Imaging

Self-Consuming Generative Models Go MAD

no code implementations4 Jul 2023 Sina AlEMohammad, Josue Casco-Rodriguez, Lorenzo Luzi, Ahmed Imtiaz Humayun, Hossein Babaei, Daniel LeJeune, Ali Siahkoohi, Richard G. Baraniuk

Seismic advances in generative AI algorithms for imagery, text, and other data types has led to the temptation to use synthetic data to train next-generation models.

Refining Amortized Posterior Approximations using Gradient-Based Summary Statistics

no code implementations15 May 2023 Rafael Orozco, Ali Siahkoohi, Mathias Louboutin, Felix J. Herrmann

We validate our method in a controlled setting by applying it to a stylized problem, and observe improved posterior approximations with each iteration.

Image Reconstruction Variational Inference

Learned multiphysics inversion with differentiable programming and machine learning

1 code implementation12 Apr 2023 Mathias Louboutin, Ziyi Yin, Rafael Orozco, Thomas J. Grady II, Ali Siahkoohi, Gabrio Rizzuti, Philipp A. Witte, Olav Møyner, Gerard J. Gorman, Felix J. Herrmann

We present the Seismic Laboratory for Imaging and Modeling/Monitoring (SLIM) open-source software framework for computational geophysics and, more generally, inverse problems involving the wave-equation (e. g., seismic and medical ultrasound), regularization with learned priors, and learned neural surrogates for multiphase flow simulations.

Geophysics

Unearthing InSights into Mars: Unsupervised Source Separation with Limited Data

1 code implementation27 Jan 2023 Ali Siahkoohi, Rudy Morel, Maarten V. de Hoop, Erwan Allys, Grégory Sainton, Taichi Kawamura

Source separation involves the ill-posed problem of retrieving a set of source signals that have been observed through a mixing operator.

Boomerang: Local sampling on image manifolds using diffusion models

no code implementations21 Oct 2022 Lorenzo Luzi, Paul M Mayer, Josue Casco-Rodriguez, Ali Siahkoohi, Richard G. Baraniuk

As implied by its name, Boomerang local sampling involves adding noise to an input image, moving it closer to the latent space, and then mapping it back to the image manifold through a partial reverse diffusion process.

Data Augmentation Image Enhancement +3

Reliable amortized variational inference with physics-based latent distribution correction

2 code implementations24 Jul 2022 Ali Siahkoohi, Gabrio Rizzuti, Rafael Orozco, Felix J. Herrmann

While generic and applicable to other inverse problems, by means of a linearized seismic imaging example, we show that our correction step improves the robustness of amortized variational inference with respect to changes in the number of seismic sources, noise variance, and shifts in the prior distribution.

Bayesian Inference Seismic Imaging +1

Ultra-Low-Bitrate Speech Coding with Pretrained Transformers

no code implementations5 Jul 2022 Ali Siahkoohi, Michael Chinen, Tom Denton, W. Bastiaan Kleijn, Jan Skoglund

Our numerical experiments show that supplementing the convolutional encoder of a neural speech codec with Transformer speech embeddings yields a speech codec with a bitrate of $600\,\mathrm{bps}$ that outperforms the original neural speech codec in synthesized speech quality when trained at the same bitrate.

Inductive Bias

Velocity continuation with Fourier neural operators for accelerated uncertainty quantification

1 code implementation27 Mar 2022 Ali Siahkoohi, Mathias Louboutin, Felix J. Herrmann

As such, the main contribution of this work is a survey-specific Fourier neural operator surrogate to velocity continuation that maps seismic images associated with one background model to another virtually for free.

Seismic Imaging Uncertainty Quantification

Learned coupled inversion for carbon sequestration monitoring and forecasting with Fourier neural operators

1 code implementation27 Mar 2022 Ziyi Yin, Ali Siahkoohi, Mathias Louboutin, Felix J. Herrmann

We show that we can accurately use a Fourier neural operator as a proxy for the fluid-flow simulator for a fraction of the computational cost.

Photoacoustic imaging with conditional priors from normalizing flows

no code implementations NeurIPS Workshop Deep_Invers 2021 Rafael Orozco, Ali Siahkoohi, Gabrio Rizzuti, Tristan van Leeuwen, Felix Johan Herrmann

For many ill-posed inverse problems, such as photoacoustic imaging, the uncertainty of the solution is highly affected by measurement noise and data incompleteness (due, for example, to limited aperture).

Deep Bayesian inference for seismic imaging with tasks

1 code implementation10 Oct 2021 Ali Siahkoohi, Gabrio Rizzuti, Felix J. Herrmann

We propose to use techniques from Bayesian inference and deep neural networks to translate uncertainty in seismic imaging to uncertainty in tasks performed on the image, such as horizon tracking.

Bayesian Inference Inductive Bias +1

Low-memory stochastic backpropagation with multi-channel randomized trace estimation

1 code implementation13 Jun 2021 Mathias Louboutin, Ali Siahkoohi, Rongrong Wang, Felix J. Herrmann

Thanks to the combination of state-of-the-art accelerators and highly optimized open software frameworks, there has been tremendous progress in the performance of deep neural networks.

Semantic Segmentation

Preconditioned training of normalizing flows for variational inference in inverse problems

2 code implementations pproximateinference AABI Symposium 2021 Ali Siahkoohi, Gabrio Rizzuti, Mathias Louboutin, Philipp A. Witte, Felix J. Herrmann

Obtaining samples from the posterior distribution of inverse problems with expensive forward operators is challenging especially when the unknowns involve the strongly heterogeneous Earth.

Variational Inference

Faster Uncertainty Quantification for Inverse Problems with Conditional Normalizing Flows

no code implementations15 Jul 2020 Ali Siahkoohi, Gabrio Rizzuti, Philipp A. Witte, Felix J. Herrmann

In inverse problems, we often have access to data consisting of paired samples $(x, y)\sim p_{X, Y}(x, y)$ where $y$ are partial observations of a physical system, and $x$ represents the unknowns of the problem.

Bayesian Inference Transfer Learning +1

Parameterizing uncertainty by deep invertible networks, an application to reservoir characterization

2 code implementations16 Apr 2020 Gabrio Rizzuti, Ali Siahkoohi, Philipp A. Witte, Felix J. Herrmann

Uncertainty quantification for full-waveform inversion provides a probabilistic characterization of the ill-conditioning of the problem, comprising the sensitivity of the solution with respect to the starting model and data noise.

Uncertainty Quantification

Transfer learning in large-scale ocean bottom seismic wavefield reconstruction

1 code implementation15 Apr 2020 Mi Zhang, Ali Siahkoohi, Felix J. Herrmann

Because different frequency slices share information, we propose the use the method of transfer training to make our approach computationally more efficient by warm starting the training with CNN weights obtained from a neighboring frequency slices.

Transfer Learning

Weak deep priors for seismic imaging

1 code implementation14 Apr 2020 Ali Siahkoohi, Gabrio Rizzuti, Felix J. Herrmann

The chief advantage of this approach is that the updates for the CNN weights do not involve the modeling operator, and become relatively cheap.

Geophysics Image and Video Processing

Uncertainty quantification in imaging and automatic horizon tracking: a Bayesian deep-prior based approach

1 code implementation1 Apr 2020 Ali Siahkoohi, Gabrio Rizzuti, Felix J. Herrmann

In this paper, we focus on how UQ trickles down to horizon tracking for the determination of stratigraphic models and investigate its sensitivity with respect to the imaging result.

Seismic Imaging Uncertainty Quantification

A deep-learning based Bayesian approach to seismic imaging and uncertainty quantification

2 code implementations13 Jan 2020 Ali Siahkoohi, Gabrio Rizzuti, Felix J. Herrmann

Uncertainty quantification is essential when dealing with ill-conditioned inverse problems due to the inherent nonuniqueness of the solution.

Seismic Imaging Uncertainty Quantification

Neural network augmented wave-equation simulation

1 code implementation27 Sep 2019 Ali Siahkoohi, Mathias Louboutin, Felix J. Herrmann

One proxy of incomplete physics is an inaccurate discretization of Laplacian in simulation of wave equation via finite-difference method.

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