Ph.D. Dissertation Defense

Relay Node Placement for
Federating Segmented Wireless Sensor Networks

Fatih Senel

2:00pm Tuesday, 10 July 2012, ITE 325b

Recent years have witnessed a growing interest in the applications of Wireless Sensor Networks (WSNs). Most notable among these applications are those operating in hostile environments space exploration, border protection, combat field reconnaissance, and search and rescue. Due to the harsh surroundings, WSNs may suffer from a large scale damage that causes many nodes to fail simultaneously and the network to get partitioned into multiple disjoint segments and its services become very limited. In such a case, restoring the network connectivity is very important in order to avoid negative effects on the applications. Linking disjoint segments may not be feasible through coordinated repositioning of some set of nodes as the scope of the damage is so wide that cannot be determined. One of the viable solutions for federating damaged WSNs is to deploy additional resources, i.e. relay nodes, to form inter-segment multi-hop paths.

In this dissertation, we tackle technical challenges related to the federation of segmented WSNs. We present a set of effective techniques that for repairing the damaged WSN using the least number of relay nodes (RNs) as well as maintaining some desirable topology features such as robustness against failures, network coverage and balanced traffic load. The correctness and time-complexity of all proposed approaches are analyzed and their performance is validated through extensive simulation experiments.

Committee: Drs. Mohamed Younis (Chair), Charles Nicholas, Samuel Lomonaco, Tim Oates, Kemal Akkaya and Waleed Youssef

MS Thesis Defense

Integrating Domain Knowledge in Supervised Machine Learning
to Assess the Risk of Breast Cancer Using Genomic Data

Aniket Bochare

9:00am Friday 29 June 2012, ITE 325b

Breast cancer is the most common form of cancer in women. Breast cancer comprises 22.9% of the invasive cancers in women and 16% of all the female cancers. Currently, treatment decisions are based primarily on clinical parameters, with little use of genomic data. Our study takes into consideration the data of postmenopausal women of European descent and their single nucleotide polymorphism (SNP) information to assess the risk of developing breast cancer. We used various supervised machine learning and data mining techniques to generate a model for predicting risk of breast cancer using only genomic data.

In this research we propose an approach to select the nine best SNPs using various feature selection algorithms to improve binary classification accuracy and validate our results with the existing literature. The machine learning model generated without the domain knowledge yields poor prediction results. After the addition of the domain knowledge of the 11 SNPs into the original training set we performed classification using the best features obtained by feature selection techniques. The machine learning model generated using both the domain knowledge and the feature selection techniques performed much better compared to the naive approach of classification.

Committee: Drs. Yelena Yesha (chair), Anupam Joshi, Aryya Gangopadhyay and Micheal Grasso

It's got a bowling alley, a piano in the lobby, a T-Rex skeleton, and eighteen cafeterias. It might sound like a theme-park, but it's the Googleplex, a.k.a. Google headquarters, located in Mountain View, California.

This extremely enlightened workplace, which features a slew of employee benefits like a free shuttle to work, laundry services, and even haircuts, might sound like an un-productive paradise, but the benefits are actually put in place to offset all the hard work and dedication of the employees.

So says an article in the Summer issue of UMBC Magazine, where Computer Science alumni Jeffrey Burgan '83 (pictured), Sandor Dornbush '06 (pictured), Jeetendra M. Soneja '04, and Robert Banz '95 talk about what it's like to work for Google.

Check out the article here.

Photo Courtesy Gabriela Hasbun

Photo Courtesy UMBC Magazine

In its latest issue, dubbed "Tech Trekkers", UMBC Magazine features Computer Science alumnus Harry Chen, one of the key players in the development of the iPhone 4S's digital assisant, Siri.

While you may have heard about Harry through an article we posted last year, the UMBC Magazine article goes deeper into Harry's story as it  follows him around the Apple campus in Cupertino, California, where he works as a software engineer.

Weaving the inspiring tale of Harry's path to success–including his spontaneous decision to pack up everything and move to the West coast in 2008–the article paints Harry as a tech wunderkind who credits at least some of his success to the environment of discovery at UMBC.

It talks about his graduate research on smart rooms ("Imagine a room that answers your questions, or anticipates your needs and then fulfills them," goes the article) and features quotes from CSEE Professors Dr. Tim Finin and Dr. Anupam Joshi, who served as his advisors during his nearly ten years at UMBC, during which time he received a B.S., M.S., and Ph.D. in Computer Science.

Want to be inspired? Check out the article here.

Originally from Almora, India, Yatish came to UMBC in 2009 to pursue his Master's in Computer Engineering. When he's not studying, Yatish likes to run, play disc golf, and read thriller novels.

About Yatish…

When did you know you wanted to study Computer Engineering?

I pursued a Bio/Math track in high school and wanted to be a doctor more than an engineer, but by 12^th grade, all the dissections in Biology turned me off and finalized my choice of Engineering.

Are you part of any labs, clubs or organizations on campus?

Yes I am part of the ESNET Lab run by Dr. Younis.

What are you researching for your thesis?

My research area is Wireless Sensor Networks, specifically algorithms and approaches to recover a network from multi node failures efficiently using distributed approaches.

Have you had any internships? 

I have interned in Samsung Electronics in 2010, working on managing Visual Display Projects related to the Hotel TV lineup.

What are your plans after graduation?

I plan to go back and work for a few years before returning to academia.

What is your dream job?

Setting up my own technical consulting firm.

On UMBC and CSEE…

What was your first impression of UMBC?

I liked the fact that everything was enclosed in a loop so it was easy to get around, and I was surprised to find that we had a nationally ranked chess team and no football team!

What was your first Computer Engineering Course?

My first Computer Engineering course at UMBC was CMSC611: Advanced Computer Architecture taught by Dr. Younis. It is one of the most fundamental classes and was one of my most favorite and enjoyable class to date.

What was your favorite Computer Engineering Course?

I would recommend CMSC611: Advanced Computer Architecture, and CMPE640: VLSI design to anyone in the CSEE program to build a solid foundation. People that enjoy playing with numbers should definitely take CMPE 645: Computer Arithmetic Algorithms.

What do you like about the Computer Science and Electrical Engineering (CSEE) Department?

I love the fact that professors and staff are easily accessible and you can stop by to ask questions or just chat.

How would you describe the professors in the department?

They are friendly and willing to help you out outside class.

What advice would you give to incoming graduate students?

Don’t forget to have fun, despite the workload.

This video is a short documentary about the LEGO Turing Machine built by Jeroen van den Bos and Davy Landman at Centrum Wiskunde & Informatica in Amsterdam.  They built the device for CWI's exposition "Turings Erfenis" in honor of Alan Turings one hundredth birthday this year and to demonstrate how simple a "universal computing device" can be.

Alan Turing was a brilliant mathematician who helped define the theoretical model of the computer as we know it today. He also made many other significant contributions to cryptology, artificial intelligence and computer sceince. He was a visionary, one of the few people of his time who recognized the role the computer would play for humanity.

The Turing Machine was defined in 1936 as an abstract model for a simple device that manipulates symbols on a strip of tape according to a table of rules. Turing Machines are not intended to be practical, but can be used to simulate the logic of any computer algorithm and to define the limits of what can be computed by real computers. You can learn more about the abstraction and why it is important by taking CMSC 451, Automata Theory and Formal Languages.

There have been many physical models built in the past, but this one is interesting because it was built with a single Lego Mindstorms NXT set. One unfortunate limitation of this Turing Machine is that it has a finite 'tape'. See the Lego Turing Machine site for more information.

Ph.D. Dissertation Defense

Fabrication and Operation of Integrated Distributed-Bragg-Reflector
Thermally Tunable Quantum Cascade Lasers

Liwei Cheng

10:00am Friday, 22 June 2012
Center for Advanced Studied in Photonics Research Conference Room

Quantum cascade lasers (QCLs) that emit in the mid-infrared (IR) range between 3 and 10 μm of the electromagnetic spectrum play an important role in optical gas sensing and molecular spectroscopic applications because several important environmental molecules such as CO, CO2, CH4, and NH3 are known to exhibit strong absorption lines in this mid-IR range. To differentiate such fine absorption features as narrow as a few angstroms, a single-mode QCL with an extremely narrow spectral linewidth, broadly tunable over the molecular absorption fingerprints and operating at sufficient optical power at room temperature, is highly desirable. We present, in this dissertation, two major studies on mid-IR QCLs, one being an improvement in device performance through a buried-heterostructure (BH) regrowth study, and the other being a realization of single-mode tunable QCLs integrated with distributed-Bragg-reflector (DBR) grating and thermal tuning mechanism.

Efficient heat dissipation in the QCL active region, which is crucial for high optical-power operation, can be effectively achieved using BH waveguides laterally embedded with InP grown by metal-organic chemical vapor disposition. We have experimentally studied the effects of the structural features of mesas, such as mesa orientation, geometry, sidewall-etched profile, and the length of the oxide overhang, on the BH regrowth. We find that the mesa oriented in the [01 1 ] direction with smoothly etched sidewalls produces a satisfactory planar growth profile and uniform lateral growth coverage and that a mesa-height–to–overhang-length ratio between 2.5 and 3.0 is effective in reducing anomalous growth in the vicinity of oxide edges. As a result, high-power QCLs capable of producing multi-hundred milliwatts at room temperature at ~4.6 μm and ~7.9 μm through reproducible BH regrowth results have been demonstrated.

We have also demonstrated single-mode tunable QCLs operating at ~7.9 μm with an internal DBR grating structure and thermal tuning scheme incorporated. A special flip-chip bonding configuration and device assembly utilizing two copper heatsinks—one for the gain section and the other for the DBR grating section—were devised and constructed to achieve separate temperature controls in both sections. A miniature thermoelectric (TE) cooler dedicated to the DBR grating section was implemented to control the DBR grating temperature while the gain section was kept at a different temperature to achieve single-wavelength tuning. Under ±1000 mA bias conditions, a quasi-single-wavelength tuning range of ~7.2 cm-1 was realized across the TE cooler temperature span, combined with an additional temperature contrast of 56 °C between the two heatsinks (gain/DBR = 10/66 °C) owing to the implementation of additional temperature-controlling elements. We have also developed a two-dimensional thermal model to investigate the thermal dynamics in the device, including the temperature distribution and thermal dependency of each section, and the thermal response time, which ultimately dictates the wavelength tuning speed. We find that a 250-μm passive section located between the gain and DBR grating section can significantly improve temperature uniformity in both the sections as it absorbs most temperature gradients. Further, a swift thermal response time of ~7 ms is simulated if the DBR grating section is directly bonded on the miniature TE cooler.

More importantly, we have realized a monolithic photonic integration platform, both thermally and electrically, for mid-IR QCLs. The QCLs fabricated in this dissertation possess two major functionalities. The gain section, an active component, is electrically pumped to provide optical gain and is kept at a temperature different from the DBR grating section, and the DBR grating section, a passive component, provides optical feedback for single-wavelength emission and subsequently tunes the emission wavelength through a local temperature variation. Such thermal and optoelectronic integration opens new perspectives for mid-IR QC technology.

Committee: Drs. Fow-Sen Choa, Anthony Johnson, Li Yan, Ryan Robucci, Terrance Worchesky and Jocob Khurgin

In its second year, the Baltimore Hackathon invites teams or individuals to build a hardware or software project from start to finish. Sporting the slogan "Meet People. Build Stuff. Have Fun.", this year's competition was held in Tide Point from June 8–10.

Among the more than ninety participants was UMBC student Ahmad Abbas, who took home the competition's DIY/Hacker prize for his hardware project. Originally from Egypt, Ahmad is finishing up his Master's degree in Computer Engineering under the supervision of Dr. Mohamed Younis in the ESNet Lab. He hopes to graduate this summer and begin Ph.D. studies at UMBC this Fall.

In the interview below, Ahmad talks about his experience at the Baltimore Hackathon and explains what made it "one of the most exciting experiences of [his] life."

How did you hear about the Baltimore Hackathon?  I heard about the Baltimore Hackathon 2012 after reading a post by Dr.Tim Finin on myUMBC on Wednesday, just two days before the competition, and I decided to join at the same day.

What is the Baltimore Hackathon? The Hackathon is a competition where you work individually or on teams with the purpose of building hardware or software in a single weekend. Participants may submit an existing project as well, but they need to indicate this before entering the competition.

In a few words, explain your winning project. When I registered, I wasn't sure about my project's idea. My idea was to build a digital camera using 1.3 MPixel CMOS camera sensor, 2.4" LCD and SD card. I decided later, during the competition, to build shields, daughter boards, for Arduino kits. These boards can be connected to Arduino kits and used in different projects.

Where did you come up with the idea? I came up with this ides because I am skilled in designing and implementing electronic circuits. Some people need these circuits to build their own projects, but they can't design or implement it. I build these circuits to help them. This idea was not only for the competition. I built my first Arduino shield last semester in Dr.Ryan Robucci's class. It is an FPGA board that can be connected to Arduino kits. This board was one of my boards in the competition, too.

I designed another two boards during the competition. One of them was a WiFi board for Arduino and the second was a Camera board for the Arduino. I built the WiFi, but I couldn't finish the camera board. Also, I built another USB enabled kit using a low-cost micro-controller and a small number of components. Last board was a DIY digital camera,  which was the original idea. I designed the board but I didn't have time to build it.       

Describe the Baltimore Hackathon. Was it stressful? Exciting? Were you intimidated by the other competitors, or did you collaborate and support one another? The Baltimore Hackathon turned out to be one of the most exciting experiences of my life. Although I was highly stressed during the competition, I was inspired by all the creative and hardworking participants.  In order to reduce the stress, participants played different games, where I earned the title of "ping pong master" and a prize to go with the title.    

I had the fortune over the course of the competition to meet Gary Mauler, Founder of Robot Fest and DIY Expo, and Amy Hurst, Assistant Professor of Human-Centered Computing at UMBC. Gary provided me with insights on how to move forward with my passion for building hardware. 

The Hackathon would not have been such an incredible experience if it were not for the organizers and volunteers who made it possible.  I would like to personally thank Jason, Kafu, Paris, and John.

Did you think you would win, or was the award a pleasant surprise? I won the Hacker DIY prize which comes with $500. I expected to win a prize because most of the participants were doing software projects.