# LIDS & Stats Tea

Tea talks are 20 minute long informal chalk-talks for the purpose of sharing ideas and making others aware about some of the topics that may be of interest to the LIDS and Stats audience. If you are interested in presenting in the upcoming seminars, please email lids_stats_tea[at]mit[dot]edu.

September 12, 2018

### Long Ties Accelerate Realistic Complex Contagions

Amin Rahimian (IDSS)

The spread of behaviors (i.e. social contagion) depends on the structure of the network of contacts between people. Interventions that change network structure can thus substantially affect how new ideas, products, and conventions are adopted. For...

September 19, 2018

### Automated As-Is Modelling of Industrial Facilities

Eva Agapaki (University of Cambridge)

The cost of modelling existing industrial facilities is currently considered to counteract the benefits of the models in maintaining and retrofitting a facility. 90% of the modelling cost is typically spent on labour for converting point cloud data...

September 26, 2018

### Microgrids for Resilient Electricity Distribution Networks

Devendra Shelar (MIT Civil and Environmental Engineering)

We propose a new approach for utilizing distributed energy resources (DERs) and microgrids for improving the resilience of electricity distribution networks to correlated cyber-physical failures. Such failures can result from random faults (e.g,...

October 3, 2018

### Direct Runge Kutta Discretization Achieves Acceleration

Jingzhao Zhang (LIDS)

We study gradient-based optimization methods obtained by directly discretizing a second-order ordinary differential equation (ODE) related to the continuous limit of Nesterov's accelerated gradient method. When the function is smooth enough, we show...

October 10, 2018

### Probability Distributions on Posets: An Application to Security Games

Mathieu Dahan (MIT Center for Computational Engineering)

We study an abstract problem regarding probability distributions on posets. The problem is to resolve the existence of a probability distribution over subsets of a poset, such that a set of constraints involving marginal probabilities of the...

October 17, 2018

### Convex Restriction: A Sufficient Convex Condition for Solvability and Feasibility of Nonlinear Equations

Dongchan Lee (Mechanical Engineering)

Convex restriction identifies the convex subset of a general nonconvex feasible set described by nonlinear equality and inequality constraints. Nonlinear optimization problems often rely on convex relaxations, which can be interpreted as convex...

October 24, 2018

### Chance-constrained Unit Commitment

Xinbo Geng (Texas A&M University)

Motivated by the uncertainties from deepening penetration of renewable energy resources in power systems, we study the day-ahead scheduling problem in electricity markets. We formulate the chance-constrained unit commitment problem considering...

October 31, 2018

### Dynamic Pricing under a Static Calendar

Jinglong Zhao (IDSS)

Our work is based on the classical dynamic pricing problem. From our collaborations with a large Consumer Packaged Goods company, we have found that while they appreciate the advantages of dynamic pricing, it is operationally beneficial for them to...

November 7, 2018

### Robust PCA over Dynamic Systems: A Case of Forced Oscillation Localization

Tong Huang (Texas A&M University)

This talk concerns about developing physically interpretable algorithms for large dynamical systems such as the power grid. The problem of source localization is formulated as one of identifying the sparse component in robust principal component...

November 14, 2018

### High-Dimensional Precision Matrix Estimation Under Total Positivity

Yuhao Wang (LIDS & EECS)

We consider the problem of estimating high-dimensional precision matrices for multivariate totally positive of order two (MTP2) distributions. Such distribution is of interest in financial econometrics, where the distribution of stock price daily...

November 20, 2018

### Attracting Random Walks

Julia Gaudio (LIDS & ORC)

We introduce the Attracting Random Walks model, which is an attractive interacting particle system. In the model, particles move between adjacent vertices of a graph G, with transition probabilities that depend positively on particle counts at...

November 28, 2018

### Delay and Stability Tradeoffs in Distributed Service Systems with Redundancy

Martín Zubeldía (LIDS)

We consider a large distributed service system with N servers that have random service rates, where there is a stream of incoming jobs that consist of K<<N identical tasks that can be executed in parallel. We assume that the K tasks from the...

December 5, 2018

### Minimal Realization Problems in Jump Linear System: Some Preliminaries

Tuhin Sarkar (LIDS & IDSS)

We address two fundamental problems in the context of jump linear systems (JLS). The first problem is concerned with characterizing the minimal state space dimension solely from input-output pairs and without any knowledge of the number of mode...

December 12, 2018

### Dispatch with Energy Storage through Constructing the Optimal Cost-to-go Function

Bolun Xu (MIT Energy Initiative)

The stochastic future can be reduced to a cost-to-go value function of the system state variable for fast and optimal real-time decision making, following the concept of dynamic programming, this serves as a potential solution to the ongoing real-...