Postdoctoral Scholar in Industrial Engineering & Operations Research

Co-PI on NSF Award 1808859. Mentor: Javad Lavaei.

**Ph.D.**, MIT, EECS, 2017. Advisor: Jacob K. White.

**S.M.**, MIT, EECS, 2012. Advisor: John G. Kassakian.

**B.E. (hons)**, University of Canterbury, EE, 2009.

My research is on **computational methods**—using advanced computational capabilities to learn from **large datasets** and solve societal problems in **energy** and **transportation**.

Many computational problems remain unsolved at the scale, speed, and quality necessary for real-world engineering. This is the case even with cloud computing, GPUs, and supercomputers! The fundamental challenge lies in the dual issues of **complexity** and **nonconvexity**. My research uses **domain expertise** to identify favorable mathematical structure, such as the graph theoretic notion of treewidth, or the existence of a hierarchy of interactions, or the low-rank factorization of a dense matrix. Then, I develop **domain-specific algorithms** to exploit such structure.

What's the deal with complexity? (A great wiki article)

Why should nonconvexity be a problem in optimization? (My answer on stack exchange)

We are applying domain-specific algorithms to real-world systems with hundreds of millions of parameters and constraints! See the US Department of Energy’s first ever Grid Optimization Competition.

**January 2019.**New paper proves that the (2,1/2)-Restricted Isometry Property (RIP) is both necessary and sufficient for the rank-1 nonconvex recovery problem to contain no spurious local minima: Sharp Restricted Isometry Bounds for the Inexistence of Spurious Local Minima in Nonconvex Matrix Recovery.**December 2018.**Presented 2 papers at__NeurIPS 2018__: (Spotlight) (Poster) How Much Restricted Isometry is Needed In Nonconvex Matrix Recovery? (Poster) A Theory on the Absence of Spurious Optimality. (Of 4856 total submissions, 1011 were accepted, including 30 orals and 168 spotlights.)**December 2018.**Invited seminar at McGill University**November 2018.**Invited seminars at Cornell University and the University of Michigan.**October 2018.**Paper on accelerating ADMM using Krylov subspace appeared in__SIAM Journal on Optimization__: GMRES-Accelerated ADMM for Quadratic Objectives.

**Sparse Semidefinite Programs with Guaranteed Near-Linear Time Complexity via Dualized Clique Tree Conversion**

R.Y. Zhang, J. Lavaei - Aug 2018. [arxiv]**Spurious Local Minima in Power System State Estimation**

R.Y. Zhang, J. Lavaei, R. Baldick - Jan 2018. [pdf]**Large-Scale Traffic Signal Offset Optimization**

Y. Ouyang, R.Y. Zhang, J. Lavaei, P. Varaiya - Jul 2018. [pdf]**How Much Restricted Isometry is Needed In Nonconvex Matrix Recovery?***Selected for Spotlight (one of 168/4856 submissions)*

R.Y. Zhang, C. Josz, S. Sojoudi, J. Lavaei -NeurIPS 2018Advances in Neural Information Processing Systems. [arxiv]**GMRES-Accelerated ADMM for Quadratic Objectives**

R.Y. Zhang, J.K. White -*SIAM Journal on Optimization*, 28.4 (2018): pp. 3025-3056. [doi] [arxiv]**Large-Scale Sparse Inverse Covariance Estimation via Thresholding and Max-Det Matrix Completion**

R.Y. Zhang, S. Fattahi, S. Soujoudi -ICML 2018International Conference on Machine Learning. [permalink] [arxiv] [slides]**Certifying Microgrid Stability Under Large-Signal Intermittency**

R.Y. Zhang, J. Elizondo, J.L. Kirtley, J.K. White -COMPEL 2016Seventeenth IEEE Workshop on Control and Modeling for Power Electronics. [doi]**Toeplitz-Plus-Hankel Matrix Recovery for Green’s Function Computations on General Substrates**

R.Y. Zhang, J.K. White -*Proceedings of the IEEE*, 103.11 (2015): pp. 1970-1984. [doi] [pdf]**Fast simulation of complicated 3D structures above lossy magnetic media**

R.Y. Zhang, J.K. White, J.G. Kassakian -*IEEE Transactions on Magnetics*, 50.10 (2014): 7027416. [doi] [pdf]**Simplified design method for litz wire**

C.R. Sullivan, R.Y. Zhang -APEC 2014IEEE Applied Power Electronics Conference and Exposition 2014. [doi] [pdf]

**Sharp Restricted Isometry Bounds for the Inexistence of Spurious Local Minima in Nonconvex Matrix Recovery**

R.Y. Zhang, S. Sojoudi, J. Lavaei - Jan 2019. [arxiv]**Sparse Semidefinite Programs with Guaranteed Near-Linear Time Complexity via Dualized Clique Tree Conversion**

R.Y. Zhang, J. Lavaei - Aug 2018. [arxiv]**Spurious Local Minima in Power System State Estimation**

R.Y. Zhang, J. Lavaei, R. Baldick - Jan 2018. [pdf]**Large-Scale Traffic Signal Offset Optimization**

Y. Ouyang, R.Y. Zhang, J. Lavaei, P. Varaiya - Jul 2018. [pdf]**Parameter Insensitivity in ADMM-Preconditioned Solution of Saddle-Point Problems**

R.Y. Zhang, J.K. White - Feb 2016. [arxiv]

**Monotonicity Between Phase Angles and Power Flow and Its Implications for the Uniqueness of Solutions**

S.W. Park, R.Y. Zhang, J. Lavaei, R. Baldick -HICSS 52Hawaii International Conference on System Sciences.

**Conic Optimization With Applications to Machine Learning and Energy Systems**

R.Y. Zhang, C. Josz, S. Sojoudi -*Annual Reviews in Control*, to appear, 2018. [arxiv]**How Much Restricted Isometry is Needed In Nonconvex Matrix Recovery?***Selected for Spotlight (one of 168/4856 submissions)*

R.Y. Zhang, C. Josz, S. Sojoudi, J. Lavaei -NeurIPS 2018Advances in Neural Information Processing Systems. [arxiv]**A Theory on the Absence of Spurious Optimality**

C. Josz, Y. Ouyang, R. Y. Zhang, J. Lavaei, S. Sojoudi -NeurIPS 2018Advances in Neural Information Processing Systems. [arxiv]**GMRES-Accelerated ADMM for Quadratic Objectives**

R.Y. Zhang, J.K. White -*SIAM Journal on Optimization*, 28.4 (2018): pp. 3025-3056. [doi] [arxiv]**Large-Scale Sparse Inverse Covariance Estimation via Thresholding and Max-Det Matrix Completion**

R.Y. Zhang, S. Fattahi, S. Soujoudi -ICML 2018International Conference on Machine Learning. [permalink] [arxiv] [slides]**Sparse Semidefinite Programs with Near-Linear Time Complexity**

R.Y. Zhang, J. Lavaei -CDC 201857th IEEE Conference on Decision and Control. [arxiv]**Efficient Algorithm for Large-and-Sparse LMI Feasibility Problems**

R.Y. Zhang, J. Lavaei -CDC 201857th IEEE Conference on Decision and Control. [pdf]**Conic Approximation with Provable Guarantee for Traffic Signal Offset Optimization**

Y. Ouyang, R.Y. Zhang, J. Lavaei, P. Varaiya -CDC 201857th IEEE Conference on Decision and Control. [pdf]**Sparse Inverse Covariance Estimation for Chordal Structures**

S. Fattahi, R.Y. Zhang, S. Sojoudi -ECC 2018European Control Conference 2018. [arxiv]**Conic Optimization Theory: Convexification Techniques and Numerical Algorithms**

R.Y. Zhang*, C. Josz*, S. Sojoudi -ACC 2018American Control Conference. [doi] [arxiv]**Spurious Critical Points in Power System State Estimation**

R.Y. Zhang, J. Lavaei, R. Baldick -HICSS 51Hawaii International Conference on System Sciences. [doi] [pdf]

**Modified Interior-Point Method for Large-and-Sparse Low-Rank Semidefinite Programs**

R.Y. Zhang, J. Lavaei -CDC 201756th IEEE Conference on Decision and Control. [doi] [arxiv]

**Robust Stability Analysis for Large-Scale Power Systems**

R.Y. Zhang - Ph.D. thesis, MIT Department of Electrical Engineering & Computer Science, 2016. [permalink] [pdf]**Small-Signal Stability Verification Issues for Transmission Systems with Distributed Renewables**

R.Y. Zhang, J. Elizondo, J.L. Kirtley, J.K. White -PESGM 2016IEEE Power & Energy Society General Meeting 2016. [doi] [pdf]**Certifying Microgrid Stability Under Large-Signal Intermittency**

R.Y. Zhang, J. Elizondo, J.L. Kirtley, J.K. White -COMPEL 2016Seventeenth IEEE Workshop on Control and Modeling for Power Electronics. [doi]**Inertial and Frequency Response from Microgrids with Induction Motors**

J. Elizondo, R.Y. Zhang, P.-H. Huang, J.K. White, J.L. Kirtley -COMPEL 2016Seventeenth IEEE Workshop on Control and Modeling for Power Electronics. [doi]

**Toeplitz-Plus-Hankel Matrix Recovery for Green’s Function Computations on General Substrates**

R.Y. Zhang, J.K. White -*Proceedings of the IEEE*, 103.11 (2015): pp. 1970-1984. [doi] [pdf]**Design of Resonance Damping via Control Synthesis**

R.Y. Zhang, A.-T. Avestruz, J.K. White, S.B. Leeb -COMPEL 2015Sixteenth IEEE Workshop on Control and Modeling for Power Electronics. [doi] [pdf]**Robust Small Signal Stability for Microgrids under Uncertainty**

J. Elizondo, R.Y. Zhang, J.K. White, J.L. Kirtley -PEDG 20156th International Symposium on Power Electronics for Distributed Generation Systems. [doi] [pdf]**An energy-based method for the assessment of battery and ultracapacitor in pulse load applications***Outstanding Presentation Award (Poster)*

Y. He, R.Y. Zhang, J.G. Kassakian -APEC 2015IEEE Applied Power Electronics Conference and Exposition 2015. [doi] [pdf]

**Fast simulation of complicated 3D structures above lossy magnetic media**

R.Y. Zhang, J.K. White, J.G. Kassakian -*IEEE Transactions on Magnetics*, 50.10 (2014): 7027416. [doi] [pdf]**Analytical model for effects of twisting on litz-wire losses**

C.R. Sullivan, R.Y. Zhang -COMPEL 2014Fifteenth IEEE Workshop on Control and Modeling for Power Electronics. [doi] [pdf]**Characterization of realistic litz wires using fast simulations***Outstanding Presentation Award (Oral)*

R.Y. Zhang, C.R. Sullivan, J.K. White, J.G. Kassakian -APEC 2014IEEE Applied Power Electronics Conference and Exposition 2014. [doi] [pdf] [slides]**Simplified design method for litz wire**

C.R. Sullivan, R.Y. Zhang -APEC 2014IEEE Applied Power Electronics Conference and Exposition 2014. [doi] [pdf]

**A Generalized Approach to Planar Induction Heating Magnetics**

R.Y. Zhang - S.M. thesis, MIT Department of Electrical Engineering & Computer Science, 2012. [permalink] [pdf]**The Future of the Electric Grid -- An Interdisciplinary MIT study**

J.G. Kassakian, R. Schmalensee et al. - Technical report, MIT Energy Initiative, 2011. [permalink]

© 2018 Richard Y. Zhang.