The goals of this seminar are to expose students, postdocs, faculty and visitors to interesting topics relevant to optimization under various aspects, for example:

- Optimization Methods and Software
- Inverse Problems (parameter estimation, imaging and sensing, etc.)
- Optimal Control
- Optimal Experimental Design (OED)
- Bayesian Inference/Inversion
- Machine Learning
- etc.,

and to provide opportunities to share new findings, and to potentially contribute with research ideas/projects.

The seminar is led by Professors Roummel Marcia and Noemi Petra and consist of graduate students, postdocs and faculty. The optimization research group meets on a bi-weekly basis to share and discuss current optimization research in the Applied Mathematics Department here at UC Merced and beyond.

## Fall 2020

For the Fall 2020 semester, seminars will take place on Thursdays from 10:30am to 11:30am, via Zoom. If you are interested to join the seminar, please contact Noemi Petra at npetra at ucmerced dot edu.

- September 10, 2020

**Roummel Marcia**(Professor, Applied Mathematics, University of California, Merced)

**Title Talk:**Optimization Methods for Machine Learning**Aditya Ranganath**(Grad Student, Electrical Engineering and Computer Science, University of California, Merced)

**Title Talk:**TBD- September 24, 2020

**Ki-Tae Kim**(Postdoc, Applied Mathematics, University of California, Merced)

**Title Talk:**MUQ-hIPPYlib: A Bayesian Inference Software Framework Integrating Data with Complex Predictive Models under Uncertainty- October 08, 2020

**Noemi Petra**(Professor, Applied Mathematics, University of California, Merced)

**Title Talk:**Optimal experimental design of large-scale Bayesian linear inverse problems under model uncertainty- October 22, 2020

**Tucker Hartland**(Grad Student, Applied Mathematics, University of California, Merced)

**Title Talk:**Hierarchical off-diagonal low-rank (HODLR) approximation for Hessians in Bayesian inference with application to ice sheet models**Radoslav Vuchkov**(Grad Student, Applied Mathematics, University of California, Merced)

**Title Talk:**Inexact Newton method with relaxed Krylov subspace approximation for inverse problems governed by PDEs- November 05, 2020

**Jacqueline Alvarez**(Grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Image Denoising With Limited Data Using Recurrent Neural Network (recording)**Alex Ho**(Grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Fundamentals of Recurrent Neural Networks (recording)- November 19, 2020

**Sarah Downs**(Grad Student, Applied Mathematics, University of California, Merced)

**Title Talk:**Classification of Forest Disturbance in California (recording)- December 10, 2020

**TBA**(Grad Student, Applied Mathematics, University of California, Merced)

**Title Talk:**TBA**Spring 2020 **

- January 30th:

**Jacqueline Alvarez**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Image Classification in Synthetic Aperture Radar using Reconstruction From Learned Inverse Scattering**Roummel Marcia**(Professor, Applied Mathematics, University of California, Merced)

**Title Talk:**Efficient Factorizations of Large-Scale Oblique Projection Matrices- February 27th:

**Toshiyuki Bandai**(grad student, Environmental Systems, University of California, Merced)

**Title Talk:**Inverse solution of Richards' equation using physics informed neural networks**Melissa Spence**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Predicting Novel and Inherited Structural Variants in Parent-Child Trios- March 12th: CANCELED - this talk is rescheduled to the end of April

**Yanting Zhao**(Ph.D. candidate, Univ Sci Tech of China (USTC), visiting Ph.D. at MESA Lab of UC Merced)

**Title Talk:**Fractional Order Gradient Descent (FOGD): An overview and future opportunities- April 2nd: CANCELED - this talk will be rescheduled for later in the Fall

**Tucker Hartland**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Hierarchical Off-diagonal Low-rank (HODLR) Approximation of Hessians for Inverse Problems with Application to Ice Sheet Flow**Ki-Tae Kim**(postdoc, Applied Mathematics, University of California, Merced)

**Title Talk:**MUQ-hIPPYlib: A Bayesian Inference So ware Framework Integrating Data with Complex Predictive Models under Uncertainty- April 16th: CANCELED

**Omar DeGuchy**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**TBA- April 30th:

**Yanting Zhao**(Ph.D. candidate, Univ Sci Tech of China (USTC), visiting Ph.D. at MESA Lab of UC Merced)

**Title Talk:**Fractional Order Gradient Descent (FOGD): An overview and future opportunities**Fall 2019 **

- September 19th:

**Alex Ho**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Image Disambiguation with Deep Neural Networks**Ki-Tae Kim**(postdoc, Applied Mathematics, University of California, Merced)

**Title Talk:**Some advances in computational methods for fracture*mechanics, linear wave propagations and eigenvalue*

*problems*

- October 3rd:

**Noemi Petra**(Assistant Professor, Applied Mathematics, University of California, Merced)

**Title Talk**: Introduction to hIPPYlib- October 17th:

**Omar DeGuchy**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Deep Learning with Pytorch (Part I)- October 31st:

**Amalia Kokkinaki**(PhD, Assistant Professor, Environmental Science, Environmental Engineering, University of San Francisco)

**Title Talk:**Large-scale inverse problems and data assimilation in hydrogeology: developments and challenges**Abstract:**In hydrogeology, inverse problems and data assimilation are used to estimate the properties of the subsurface using noisy, indirect measurements, as well as to track fluid movement through the soil or rock matrix. Applications include characterization for improved site cleanup, water resources management, and identification of contaminant sources. The corresponding inverse problems range from weakly nonlinear, such as pressure dissipation in mildly heterogeneous formations, to strongly nonlinear, such as multiphase flow in heterogeneous formations. A variety of techniques have been used over the last two decades to tackle such inverse problems, including deterministic/regularization based techniques to stochastic Bayesian estimation techniques. In this talk, a review of these methods will be presented, focusing on methods that are applicable for large scale systems with thousands to millions of unknowns, and specifically addressing the tradeoff between computational efficiency and estimation accuracy. The challenges associated with strongly non-linear problems, and Kalman Filtering variants that can address such problems will be discussed. The talk will close with an overview of current research needs for inverse modeling methods in the field of hydrogeology.

- November 14th:

**Omar DeGuchy**(grad student, Applied Mathematics, University of California, Merced)

**Title Talk:**Deep Learning with Pytorch (Part II)- December 5th:

**Tucker Hartland**, (grad student, Applied Mathematics, University of California, Merced)

*Title Talk: Hierarchical Off-Diagonal Low-Rank Approximation forHessians in Inverse Problems*

**Radoslav****Vuchkov**(grad student, Applied Mathematics, University of California, Merced)

*Title Talk: Quasi-Newton Methods for Infinite-Dimensional Inverse Problems Governed by PDEs*

**Spring 2019 **

- February 14th:

Omar DeGuchy (grad student, Applied Mathematics, University of California, Merced)

*Title Talk: The Fundamentals of Deep Learning*

- February 21st:

Tucker Hartland (grad student, Applied Mathematics, University of California, Merced)

*Title Talk:*

*Hierarchical Off-diagonal Low-rank Approximation for Hessians in Inverse Problems*

- March 7th:

Roummel Marcia (Professor, Applied Mathematics, University of California, Merced)

*Title Talk: Quasi-Newton Methods for Off-the-Shelf Machine Learning*

- March 21st:

Ekkehard Sachs (Professor, Trier University)

*Title Talk: Second-order adjoints in optimization with application*

*to machine*

*learning for the training of neural networks*

- April 4th:

Radoslav Vuchkov (grad student, Applied Mathematics, University of California, Merced)

*Title Talk: On mesh-independent secant quasi-Newton formulas*

- April 18th:

Lekan Babaniyi (postdoc, Applied Mathematics, University of California, Merced)

*Title Talk: Bayesian inversion for the basal sliding parameter field in a nonlinear Stokes ice sheet model with a nuisance rheology parameter in hIPPYlib*

- May 2nd:

Derek Hollenbeck

*Title Talk: Odor Plume Problems and Introduction to POSIM*