Graduate

ISL Colloquium

Topic: 
Reed-Muller Codes — An Oldie but Goodie
Abstract / Description: 

Reed-Muller codes are among the oldest and best studied families of codes. They have many beautiful and useful properties. Recently they have drawn renewed interest due to their close relationship with Polar codes. This begs the question: Do they achieve capacity?

Based on joint work with S. Kudekar, M. Mondelli, and E. Sasoglu.

Date and Time: 
Thursday, May 28, 2015 - 4:15pm to 5:15pm
Venue: 
Packard 101

A Scalable Architecture for Ordered Parallelism

Topic: 
A Scalable Architecture for Ordered Parallelism
Abstract / Description: 

We present a new parallel architecture that exploits fine-grain ordered parallelism, which is abundant but hard to mine with current software and hardware techniques. In this architecture, called OP, programs consist of fine-grain tasks, as small as tens of instructions each, with programmer-specified order constraints. OP executes tasks speculatively and out of order, and efficiently speculates thousands of tasks ahead of the earliest active task to uncover enough parallelism. Furthermore, OP sends task to run close to their data whenever possible, reducing data movement. We contribute several new techniques that allow OP to scale to large core counts and speculation windows, including a new execution model, speculation-aware hardware task management, selective aborts, and scalable ordered task commits.

We evaluate OP with challenging graph analytics, simulation, and database benchmarks. At 64 cores, OP achieves speedups of 32-64x over a single-core OP system, and achieves even higher speedups over state-of-the-art parallel software algorithms.

Date and Time: 
Wednesday, May 27, 2015 - 2:00pm to 3:00pm
Venue: 
Gates 104

System Solutions that Enable Ubiquitous Adoption of Solar Energy

Topic: 
System Solutions that Enable Ubiquitous Adoption of Solar Energy
Abstract / Description: 

The talk focuses on system solutions that are beginning to transform the solar industry. In particular, I would like to highlight a number of system level solutions my group was responsible for at SunEdison. These solutions touch all the key segments of the solar market.

  • In the utility space, it is all about mitigating intermittency and improving generation efficiency
  • For the commercial market it is about deployment efficiency and monitoring the production
  • For the residential market the need is for efficient integration of PV and energy storage
  • In the case of off-grid systems to serve the rural and remote populations with limited or no access to electricity, providing low cost firm power solutions become necessary

I will review some of these solutions and the engineering challenges we face to make solar adoption ubiquitous as well as point out opportunities for innovation.

Date and Time: 
Wednesday, May 20, 2015 - 4:15pm to 5:15pm
Venue: 
540-108, Blume Earthquake Center

IT-Forum

Topic: 
A Topic Modeling Approach to Learning Preference-Behavior from Pairwise Comparisons
Abstract / Description: 

The recent explosion of web analytics tools has enabled us to collect an immense amount of partial preferences for large sets of items such as products from Amazon, movies from Netflix, or restaurants from Yelp, from a large and diverse population of users through transactions, clicks, etc. Modeling, learning, and ultimately predicting the preference behavior of users from pairwise comparisons has been extensively studied since the 1927 work of Thurstone. Yet, almost all models to date have been founded on a clustering-perspective in which users are grouped by their preference behavior.

We take a fundamentally different decomposition-perspective and propose a new class of generative models for pairwise comparisons in which user preference behavior can be decomposed into contributions from multiple shared latent "causes" (partial orders) that are prevalent in the population. We show how the estimation of shared latent partial orders in the new generative model can be formally reduced to the estimation of topics in a statistically equivalent topic modeling problem in which causes correspond to topics and item-pairs to words. We show that an inevitable consequence of having a relatively small number of shared latent causes in a world of large number of item-pairs is the presence of "novel" item-pairs for each latent cause. We then leverage recent advances in the topic modeling literature and develop an algorithm based on extreme-point identification of convex polytopes to learn the shared latent partial orders. Our algorithm is provably consistent and comes with polynomial sample and computational complexity guarantees. We demonstrate that our new model is empirically competitive with the current state-of-the-art approaches in predicting preferences on semi-synthetic and real world datasets.

This talk is based on joint work with Weicong Ding and Venkatesh Saligrama at Boston University.

Date and Time: 
Friday, May 22, 2015 - 1:00pm to 2:00pm
Venue: 
Packard 202

EE380 Computer Systems Colloquium

Topic: 
Inventing the Inventor: Transforming a Generation of Minecraft Players Into Engineers
Abstract / Description: 

Technology influences every part of our lives, and children grow up digital natives. But this proximity does not guarantee an understanding or grasp of the underlying workings of the machines we use. We saw that kids today are great consumers, but not great creators of technology. We wanted to change that. And make it fun.

If you love the idea of empowering kids and teaching them to tap their inner inventor, join us, share your ideas, support our work, and help make it happen.

Date and Time: 
Wednesday, May 20, 2015 - 4:15pm to 5:30pm
Venue: 
Gates B01

SystemX Seminar

Topic: 
Sub-THz On-Chip CMOS Harmonic Frequency Generation, Transmitting and Receiving
Abstract / Description: 

With the advancement of CMOS technology, it has become possible to build compact and low cost sub-millimeter wave signal sources as local oscillator, and even to integrate entire transmitters and receivers on-chip. However, current signal source generation and transmission on CMOS technology suffer from poor performance in terms of output power and bandwidth due to the limited cut-off frequency fmax of the transistor.

In this talk, we propose ways of extending the operation frequency of CMOS around and above fmax on the range of sub-THz, and improving the performance of the signal sources and the down-converters. For that, a new topology of Colpitts VCO is introduced to answer simultaneously for the demand in high output power and wide tuning range. The harmonic approach is proposed to exploit higher harmonics of the fundamental Colpitts VCO topology to reach operation frequencies above the fmax. New design approaches and techniques are proposed and show state of the art performance.

For the signal generation, a model is developed for the Colpitts VCO to show analytically the amplitude behavior of the fundamental and the higher harmonics. While for the signal down-conversion, a model is developed to examine how the LO harmonics impact the conversion gain and NF of the down-converter operated above fmax.

To corroborate the theoretical analysis, the analytical models, the simulations and the circuit design, we show the design and the results of fabricated chips on different CMOS technologies. These chips validate the modeling, analysis and design we introduce, while demonstrating state of the art results in the 130-320 GHz range.

Date and Time: 
Thursday, May 28, 2015 - 4:00pm to 5:00pm
Venue: 
Packard 202

ISL Colloquium

Topic: 
Queueing with Redundant Requests: First Exact Analysis
Abstract / Description: 

Recent computer systems research has proposed using redundant requests to reduce latency. The idea is to replicate a request so that it joins the queue at multiple servers, where the request is considered complete as soon as any one copy of the request completes.

The performance analysis of systems with redundant requests is very hard, and only approximations and bounds exist. We will present the first exact analysis of systems with redundancy. We allow for any number of classes of redundant requests, and number of classes of non-redundant requests, any degree of redundancy, and any number of heterogeneous servers. We derive the limiting distribution on the state of the system.

We seek to understand the benefit and pain caused by redundancy and to compare redundancy with other smart resource allocation schemes. Our analysis leads to some surprising results on the effectiveness of redundancy.

Based on joint work with: Kristen Gardner, Sam Zbarsky, Sherwin Doroudi, Alan Scheller-Wolf. To appear in SIGMETRICS 2015.

Date and Time: 
Thursday, May 21, 2015 - 4:15pm to 5:15pm
Venue: 
Packard 101

Grad Student Open Panel Q&A

Topic: 
Open Panel Q&A
Abstract / Description: 

A Panel for EE Graduate Students:

Looking for guidance on the next steps for your graduate career? Register to attend a panel of professors and advanced graduate students to answer your questions!

Please join us for this open discussion on topics such as:

 

  • Finding a research advisor
  • Making the most of your summer
  • Planning for the upcoming academic year
  • Transitioning from a course curriculum to research
  • Any related question on your mind!

 

Panelists: Professor Andrea Goldsmith, Professor Olav Solgaard, and 3 current PhD students (Myungheon Chin, Irena Fischer-Hwang, Chris Rogers)

Your questions are encouraged and all EE students are welcome. Pizza will be served!

Please RSVP here so we can get enough for everyone.
http://goo.gl/forms/78riFmn4P2

 

Hosted by Graduate Students in Electrical Engineering (GSEE)

Date and Time: 
Monday, May 18, 2015 - 3:00pm to 4:00pm
Venue: 
AllenX Auditorium

SystemX Seminar

Topic: 
Universal Wireless Transport: from Rhetoric to Reality
Abstract / Description: 

Tarana has made fundamental advances in radio performance that power industry's first truly viable wireless transport alternative to the high cost and complexity of fiber. With traditional wireless technologies, performance becomes very unpredictable in environments where links are obstructed by buildings and interfered with by neighboring links, which is typical in densely populated urban areas. As a result, networks today have struggled to scale their capacities in order to meet the growing demand in mobile data. In contrast, with Tarana's adaptive beam technology, networks maintain peak or near peak performance even in dense urban deployments. For network operators, this not only means significant reduction in costs associated with network planning and maintenance, but also much better utilization of spectrum assets. Tarana's solution features advanced interference cancellation technology that increases spectral efficiency by 10-50x compared to state-of-the-art cellular technologies, and improves reliability in unlicensed spectrum.

In this talk, we give an overview of Tarana's universal wireless transport technology and discuss different applications where it can be used to support mobile data explosion in the coming decade. We also review the methodology for validating different performance claims in both theory and practice.

Date and Time: 
Thursday, May 14, 2015 - 4:00pm to 5:00pm
Venue: 
Packard 202

Seminar: Energy is a commodity

Topic: 
Energy is a commodity
Abstract / Description: 

Energy, water and waste management will be the 3 big challenges that our kids' generation will be grappling with in the next 3 decades. Already, the voracious energy appetite of the fast-rising economies of developing countries overshadows the global power generation capabilities. What are the possible solutions? How is commoditized solar power being made available to the millions in these rising nations? What are the challenges? Is this problem limited to only those with low affordability? These are some of the topics we will discuss during this lecture.

Date and Time: 
Wednesday, May 13, 2015 - 4:15pm to 5:30pm
Venue: 
540-108, Blume Earthquake Center

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