PHY2603H Inverse Theory, 2021-2022

 

  News/Notice
  • First class: Sep 13, 11-12
  • Marking scheme: 5 assignments (each 15%), final project (25%)
  • Important dates: First class on 09/13, Thanksgiving 10/11, Reading week 11/8-12, classes end on 12/08; Lecture dates: 09/13,15,20,22,27,29; 10/4,6,13,18,20,25,27; 11/1,3,15,17,22,24,29; 12/2,7,9
  • Course Syllabus

 

Time
  • Lectures: Monday/Wednesday 11-12, MP505
  • Office hours: Monday 4:15-5:15 pm and Wednesday 2-3 pm
Lecturer
Instructor: Qinya Liu
Office: MP 504A
Phone: 416-978-5434
Email: liuqy AT physics.utoronto.ca

Basic Topics
  • What is inverse theory in physics and geophysics? When do data-consistent models even exist?
  • Multivariate regression modeling of discrete models, Bayesian approaches, maximum likelihood estimation, with errors and hypothesis testing, both classical and resampling(e.g. bootstrap)
  • Continuous models where spatial resolution is a meaningful concept (Backus-Gilbert theory)
  • Singular Value Decomposition approach to modeling
  • Answerable and unanswerable questions in modeling
  • Exotic norms such as L-1, compressive sensing
  • Methods for non-linear modeling and global optimization: e.g. Markov Chain Monte Carlo (MCMC), simulated annealing, genetic algorithms, etc

 

Reference Books
In addition to the main textbook, you may find the other following books/notes useful:

 

Course Schedules
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Lecture No. Slides Content Reading HW
1,2 Introduction examples of inverse problems; models, forward problems; continuous/discrete inverse problems; existence, uniqueness and stability of inverse problems. Chapter 1 N/A
3,4,5,6 Least squares, Resampling under/over/even-determined problems; prediction error; goodness of fit and chi-square statistics; model covariance and resolution; error propagation, maximum likelihood estimator, Bayesian inference Chapter 2 HW 1 (Due 10/6),
HW 2+ HW2.1 bootstrap(horm.m; Due 10/27)
7,8,9,10 Linearized inverse problem linearization of weakly nonlinear inverse problem, variance and resolution trade-off; ill-posed problems, regularization, SVD, pseudo-inverse, L-curve Chapter 3 HW 3: Aster 2013, Page 87, section 3.6, question 2, and 4 (Due on 11/10)
11,12,13,14 Tikhonov regularization regularizations, cross-validation Chapter 4 HW4: Aster 2013, section 4.9, Page 124, question 2 and 3: data and regularization tools (needs to be unzipped, e.g., by 7-zip) from Mathworks, due 11/24
15,16 Iterative methods for nonlinear optimization Newton's method, conjugate gradient method and preconditioning Chapter 6 HW 5: Page 167, 5, 6, due on Dec 8, 11:59 pm
17,18,19,20 Miscellanenous subjects non-negative constraints, total variation regularization; computation of data kernels; Backus and Gilbert resolution analysis Chapter 7, Chapter 5
21 Global optimization methods Monte Carlo methods; direct search; uniform random search; simulated annealing; metropolis algorithm; genetic algorithm Review Paper Project (see below for info
Dec 21 Project Paper Due 7-8 page report on ONE of the following subjects: 1) Global optimization methods focusing on simulated annealing, genetic algorithm or other global search techniques; 2) Neighborhood Algorithms (Paper 1, Paper 2); 3) Optimization problem, compressive sensing and applications (see Tex notes section 11.1); 4) Optimization problems, machine learning, neural networks and applications (see section 11.2 of Tex notes) Review Paper by Sambridge & Mosegaard (2002) Due on Dec 21, 11:59 pm

 

 

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