Graduate

ISL Colloquium: Security using physical dynamics

Topic: 
Security using physical dynamics
Abstract / Description: 

In this talk, we explore how physical resources and dynamics can be an enabler in enhancing security. We illustrate this through results in two topics: wireless network security and security in cyber-physical systems.

Wireless networks provide plentiful resources to construct security: the existence of feedback (today part of all wireless standards); the possibility of selecting and using multiple paths; the smart use of wireless jamming; the wireless channel variability and unpredictability. Individually each of these properties has been identified as enabling security, and interesting results over specific network topologies have been developed, but we do not yet have a unifying theory that links all of them together. In this talk we describe our first steps on building such a framework for erasure networks, which capture many of the important characteristics, but are more tractable to analyze. We develop several results for interactive security for this model, including group key generation, message security, private message broadcasting and oblivious transfer. We will describe some mechanisms that can create erasure channels starting from wireless physical channels. We will then describe our experience in validating some of these results through preliminary experimental results on a test bed.

Critical physical infrastructures, such as electrical grids and water networks etc., are increasingly controlled through a distributed cyber-systems which make it vulnerable to attacks. For CPS security, just protecting bits is insufficient as sensor attacks can manipulate physical signals before its conversion to bits, rendering cyber-encryption ineffective. By drawing insights from error correction, we develop defense strategies that utilize the physical dynamics of CPS. We demonstrate this for the state estimation problem in the presence of attacks on sensors and actuators and characterize the resilience of a system which corresponds to the maximum number of attacks that can be tolerated while successfully reconstructing the state from observations.

This talk is joint work with L. Czap, C. Fragouli, V. Prabhakaran, S. Mishra. H. Fawzi, Y. Shoukry, N. Karamchandani and P. Tabuada. Some parts are also joint work with K. Argyraki, B. Dey and M. Mishra.


Refreshments will be served after the talk.

Date and Time: 
Thursday, April 23, 2015 - 4:15pm to 5:15pm
Venue: 
Packard 101

EE Special Seminar

Topic: 
Aging characterization of scaled Metal Gate / High-K devices and its impact on CMOS circuit degradation
Abstract / Description: 

Time-zero variability and variability induced by device aging is a growing concern for aggressively scaled transistor technologies with metal gate/high-k stacks. Bias temperature instability (BTI) in PMOS and NMOS devices is considered the most dominant time-dependent variability contributor and needs to be modeled using stochastic processes. The physical nature of the stochastic process is still under debate and to support model development efforts large statistical data sets are essential. In this presentation, we will focus on the characterization challenges related to the BTI process in large and small area CMOS devices and discuss how to obtain discrete SRAM and logic device level data beyond 3s. We will further illustrate the impact of the stochastic variation on CMOS circuits like SRAM and ring-oscillators. Finally we will highlight opportunities for application of time-resolved electrical characterization methods to improve the understanding of novel devices.

Date and Time: 
Friday, April 24, 2015 - 3:00pm to 4:00pm
Venue: 
Gates 104

EE380 Computer Systems Colloquium: Online Arms Race

Topic: 
Online Arms Race
Abstract / Description: 

There is an accelerating arms race going on in the online world. We have all extended our lives from the real world to the online world. However, our data and our privacy is being threatened by attackers in the online world. We have to fight online criminals and online hacktivists. And - a bit surprisingly - we nowadays also have to fight online attacks that are originating from governments. How did we end up to this situation? Where are we going next? And what should we do?

Date and Time: 
Wednesday, April 22, 2015 - 4:15pm to 5:15pm
Venue: 
Gates B01

Fuse!

Topic: 
volleyball
Abstract / Description: 

Happy Spring Quarter!! The weather is beautiful, so let's take advantage of it and play some volleyball! We'll set up volleyball nets on the grass outside of Packard—if you want to help set up, come at 3:45, otherwise you can join us at 4 to play! If volleyball isn't your thing, you can still come and enjoy the sunshine with us!

Hopefully we'll see you there!

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More about Fuse: ee.stanford.edu/student-resources/student-organizations

Date and Time: 
Friday, April 17, 2015 - 4:00pm to 6:30pm
Venue: 
Packard lawn

GSEE (Graduate Students in Electrical Engineering) Event

Topic: 
Meditation Session
Abstract / Description: 

GSEE is hosting a free 1-hour meditation session. Please register; there are a limited number of spots available. First-come first-serve and affiliation with the EE department. If you are interested, please sign up here (expired). We will let you know by next Wednesday, 4/22/15.

Date and Time: 
Friday, April 24, 2015 - 4:00pm to 5:00pm
Venue: 
TBA

IT-Forum

Topic: 
Sub-optimality of the Han-Kobayashi region for the interference channel: Remarks on computing regions expressed by auxiliaries
Abstract / Description: 

A computable characterization of the capacity region for the two receiver interference channel, along with that of the two receiver broadcast channel, constitute two of the most fundamental open questions in network information theory. A computable achievable region proposed by Han and Kobayashi (1981) was the best-known achievable region and its optimality or sub-optimality had not been established prior to this work. In this work, we show that coding across time-slots can improve on Han-Kobayashi region (also known as multi-letter inner bounds).

The talk will be mainly about the various ideas and developments that eventually led to this result. It touches upon various computational aspects of computable regions or in other words, the study of extremal auxiliaries.

A similar result about Marton's achievable region for broadcast channels has not been found yet; and the difficulty lies precisely in the narrowing of extremal auxliaries, although significant progress has been made in this direction in the past few years.

This will be a whiteboard talk and though there is a rough outline, the talk can be steered by the audience.

Date and Time: 
Friday, May 15, 2015 - 1:00pm to 2:00pm
Venue: 
Packard 202

IT-Forum: Social Learning in Decision-Making Groups

Topic: 
Social Learning in Decision-Making Groups
Abstract / Description: 

People have always been influenced by the opinions of their acquaintances. Increasingly, through recommendations and ratings provided on all sorts of goods and services, people are also influenced by the opinions of people that are not even acquaintances. This ubiquity of the sharing of opinions has intensified the interest is the concept of herding (or informational cascades) introduced in 1992. While agents in most previous works have only individualistic goals, this talk focuses on social influence among agents in two collaborative settings.

We consider agents that perform Bayesian binary hypothesis testing and, in addition to their private signals, observe the decisions of earlier-acting agents. In the first setting, each decision has its own corresponding Bayes risk. Each agent affects the minimum possible Bayes risk for subsequent agents, so an agent may have a mixed objective including her own Bayes risk and the Bayes risks of subsequent agents; we demonstrate her tension between being informative to other agents and being right in her own decisions, and we show that she is more informative to others when she is open minded. In the second setting, opinions are aggregated by voting, and all agents aim to minimize the Bayes risk of the team's decision. We show that social learning is futile when the agents observe conditionally independent and identically distributed private signals (but not merely conditionally independent private signals) or when the agents require unanimity to make a decision. Our experiments with human subjects suggest that when opinions of people with equal qualities of information are aggregated by voting, the ballots should be secret. They have also raised questions about rationality and trust.

Date and Time: 
Friday, April 24, 2015 - 1:00pm to 2:00pm
Venue: 
Packard 202

IT-Forum: Distributed Estimation of Generalized Matrix Rank: Efficient Algorithms and Lower Bounds

Topic: 
Distributed Estimation of Generalized Matrix Rank: Efficient Algorithms and Lower Bounds
Abstract / Description: 

We study the following generalized matrix rank estimation problem: given an n×n matrix and a constant c≥0, estimate the number of eigenvalues that are greater than c. In the distributed setting, the matrix of interest is the sum of m matrices held by separate machines. We show that any deterministic algorithm solving this problem must communicate Ω(n^2) bits, which is order-equivalent to transmitting the whole matrix. In contrast, we propose a randomized algorithm that communicates only O(n) bits. The upper bound is matched by an Ω(n) lower bound on the randomized communication complexity. We demonstrate the practical effectiveness of the proposed algorithm with some numerical experiments.

Date and Time: 
Friday, April 17, 2015 - 1:00pm to 2:00pm
Venue: 
Packard 202

Applied Physics/Physics Colloquium: Special Seminar

Topic: 
The Phases of Hard Sphere Systems
Abstract / Description: 

One of the simplest models of statistical mechanics is a system of identical hard sphere particles, placed inside a box whose energy and volume are free to fluctuate in response to an environment characterized by a temperature and pressure. A dimensionless pressure parameter p is formed from a combination of the sphere radius, the temperature, and the pressure of the environment. Qualitatively different average properties of the sphere packing are controlled by this dimensionless pressure: a "disordered" gas phase at small p and an "ordered" crystalline phase at large p. Since all (nonintersecting) sphere configurations are isoenergetic, the mechanism for crystalline ordering, called "order by disorder", is purely entropic in nature. Sphere packings having the highest possible density correspond to the limit of infinite p.


In addition to providing a physicist's intuition on the existence of phases in the hard sphere system, this tutorial talk will also touch on topics of mathematical interest. In the limit of many spheres (so "magic number" effects are minimized), does statistical mechanics distinguish among the different densest structures that arise in three dimensions? In higher dimensions, where much less is known, might we expect more than two phases, or perhaps just a single phase?

Applied Physics event page

Date and Time: 
Wednesday, April 22, 2015 - 4:00pm to 5:00pm
Venue: 
Building 380, Room 384-I

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