Fall 2000 Poster Session Abstracts

Mark Bilezikjian
Affiliation: Letters & Science Computer Science
Advisor: Prof. James Landay (EECS)
Others: Scott Klemmer, Regan Mandryk, and Kori Inkpen

This poster presents work that investigates a new interaction paradigm for handheld computing: the use of multiple interconnected handheld devices to form a virtual shared workspace. Given the importance of rich, social interactions of children, we wanted to explore ways to effectively support children’s collaboration on handheld computers.

We built our collaborative system on top of Geney, an educational software research project at Simon Fraser University. Geney is a Palm OS application for teaching middle school students about genetics; kids try to produce fish with specific traits by "Marrying" fish. We began with paper prototypes; performing participatory design with two groups of seventh graders that had previously played Geney. With the kids, we designed and implemented a multiple Palm application where information about particular fish is shared among peers via infrared, trait percentages of possible outcomes are displayed on the screens, and the groups are free to discuss the possibilities and trade fish.

The system facilitates children’s synthesis of information and discussion during the collaborative activity. We then conducted an exploratory study of the new interaction paradigm with seven 7th and 8th grade participants, observing children’s use of this new interaction paradigm, and gaining feedback on the WHAT-IF feature. The results of this work illustrate the potential of handheld computers for supporting children’s social interactions in collaborative learning activities.

Alvise Bonivento
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. Joseph Kahn (EECS)

Free-Space Optical Communications with Imaging Receivers
through Atmospheric Turbulence Channels

Free-space optical links using direct beams and imaging receivers can achieve multi-gigabit-per-second transmission over kilometer ranges. The objective of this research is to investigate how atmospheric turbulence can degrade the performance of free-space optical links, particularly over ranges of the order of 1 km. Inhomogeneities in the temperature and pressure of the atmosphere lead to variations of the refractive index along the transmission path and these effects can significantly increase the error probability in the link. We plan to do experiments in real atmospheric turbulence channels to verify the validity of the theoretical physical model and the theoretical detection schemes proposed for this particular type of transmission. We will work in the regime in which the imagine receiver has a diameter smaller than the turbulence coherence and also the observation interval is smaller than the coherence time. Once we get knowledge of the statistic of the fading (marginal and if possible also the joint temporal statistic), we will also be able to design and optimize receivers using maximum-likelihood detectors (symbol-by-symbol or a sequence detection in the case of known joint temporal distribution) using Markov chain models and channel coding.

Billy Chen
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. Ken Goldberg (IEOR)

We use the term "collaborative control" to describe any system where inputs from many processes are combined to generate control signals for a single resource such as a mobile robot. Experimental evidence with subsumption and behavior suggests that such systems perform surprisingly well and are robust to noise and uncertainty. In this paper we propose a formal model to study collaborative control. In this model, each process is represented by an agent whose behavior is modeled by a deterministic finite automaton (DFA) with the ability to vote on the motion increment of a global cursor; half the agents control the horizontal motion, the other half vertical, the goal is to make the cursor follow a given circular trajectory.

We measure performance of the system by the average error between the generated trajectory and the given circular trajectory. We find that our model is surprisingly robust to drop-outs, randomness, time-delay, and even malicious behavior. We develop an analytic model to explain these results. We believe this is the first formal model that confirms experimental results reported with subsumption and other behavior-based architectures. This model can also provide insight into collaborative control systems where agents interact over the Internet.

Andy Chou
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. Marti Hearst (SIMS)

FLAMENCO: FLexible information Access using
MEtadata in Novel COmbinations.

Our end goal is to develop a general methodology for specifying task-oriented search interfaces across a wide variety of domains and tasks. We suggest that rich, faceted metadata be used in a flexible manner to give users information about where to go next, and to have these suggestions and hints reflect the users’ individual tasks. We have created a backend with various programming languages to help us understand, implement, and evaluate search interfaces.

Dino DiCarlo
Affiliation: Department of Bioengineering
Advisor: Prof. Luke Lee (BioE)

Simulations of Near-Field Excitation and Trapping
for Integrated Near-Field Optical Microfluidic Devices

Simulations of near-field excitation and trapping at 100 nm apertures were conducted to aid design of an integrated near-field optical device for detection and manipulation of molecules in fluidic microchannels. The simulations indicate that optical trapping will occur at near-field aperture edges, and if plane-polarized light is used the trapping edge can be selective. By changing the plane of polarization the position of the trap can be rotated. The near-field apertures have been fabricated inside microchannels using a novel batch micromachining process. The process consists of patterning micron size holes in a silicon nitride membrane, which are then reduced in size through the redeposition of silicon nitride thin films. Nanoholes down to 100 nm in diameter have been fabricated.

Alex Fabrikant
Affiliation: Department of Electrical Engineering & Computer Sciences
Work done at Xerox PARC (via UC Berkeley EECS Internship Program & PARC Undergraduate Internship Program), jointly with Tad Hogg

We present a quantum computer heuristic search algorithm for graph coloring. This algorithm uses a new quantum operator, appropriate for nonbinary-valued constraint satisfaction problems, and information available in partial colorings. The algorithm is evaluated empirically with small, critically-constrained graphs near a phase transition in search performance. It improves on two prior quantum algorithms: unstructured search and a heuristic applied to the satisfiability (SAT) encoding of graph coloring. An approximate asymptotic analysis indicates the algorithm can be tuned to give polynomial-time cost for hard graph coloring problems, on average. Limitations of simulations with current computers only allow empirical testing of this approximation for small graphs.

Sid Gazor
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. Michael Lieberman (EECS)

Develop simple demonstration experiments for plasma physics and engineering for students from junior high school level to college undergraduate level. The first demonstration will be to develop a Langmuir probe experiment based on use of a gas-filled triode tube. Later experiments will be developed to illustrate the principles of capacitive and inductive RF discharges, by powering the gas-filled tube with a 13.56 MHz radio frequency source.

Jasmine Han
Affiliation: Department of Bioengineering
Advisor: Prof. Ted Cohn (BioE)
Graduate Student Mentor: Joseph (Jay) E. Barton

This research involves the design and proof of concept of a computer-based system that makes use of an electro-optic mouse (IntelliMouseÒ ) to measure the postural sway of a person. Existing methods and instruments are either inaccurate or expensive. This new diagnostic device use an optic mouse that is attached to a hat on the patient’s head. The corresponding postural sway made by the patient is sketched on a graph. Together, the total distance moved by the patient during the test as well as the maximum sway relative to the starting point are recorded. All these measurements are taken using a MATLAB program.

Analysis of the data shows that a trace of postural sway can be readily obtained. Measured postural stability is better with eyes open than with eyes closed. Further modifications are under study. This device is intended to help neurologists and specialists in related areas to accurately and easily investigate a patient’s neurological dysfunction using an inexpensive and efficient means of estimating postural stability.

James Hendricks
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. David Culler (EECS)

Large, scalable systems are an increasingly important part of modern internet server applications. One method for increasing the scalability of such systems is to implement non-blocking routines. While other Java IO systems already have non-blocking interfaces, there are no non-blocking disk IO interfaces. This project will provide a non-blocking disk IO library for Java using the Java Native Interface under Linux. The purpose of this project is to incorporate non-blocking disk IO libraries into UC Berkeley’s NBIO project, which aims to make non-blocking interfaces to many forms of Java IO. The NBIO framework will allow for high-performance single-threaded servers written in Java.

Matthew Kam
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. John Canny (EECS)

LiveNotes is a multithreaded Java program that runs on WinCE Clios over wireless TCP/IP networks. Its primary function is to facilitate collaborative note-taking in groups of up to 4 members. In each group, a member acts as the main note-taker, with the other members adding their comments to the shared transcript. LiveNotes has its theoretical foundation in Bakhtin’s dialogical social theory of learning, and aims to enhance the peer learning experience by exposing group members to one another’s "voice" in real-time.

Akanksha Kejriwal and Arlen Khodadadi
Affiliation: Department of Industrial Engineering & Operations Research
Advisor: Prof. Lee Schruben (IEOR)

This project explores methods of simulating customer-server interaction systems on a web server. The discrete event simulations were designed using the event-graph method using a simulation package called SIGMA. The models were then converted into C code. Active Server Pages (ASP) and html were used primarily for the execution of the simulation on the web, and for the development of user interfaces. In addition, other web-based technologies such as Flash were used for user interface development.

The initial test model was the simulation of a car-wash system. Following this, a small business model was developed with the intention of allowing small businesses to access simulation on the web at an affordable price. The model built for this purpose is a multiple server and multiple customer system that aims to help users with the analysis of the segments in the target market and with workforce planning.

Josephine Kung
Affiliation: Department of Electrical Engineering & Computer Sciences
Advisor: Prof. Kris Pister (EECS)

In the field of microelectromechanical systems (MEMS), cross-sections of structures are useful. Traditional methods of cleaving, or splitting, a chip in order to obtain its cross-section have been either impractical or imprecise. For instance, scratching along the surface of the chip (i.e., with a diamond scribe) and breaking it along the line will give a clean cross-section, but will not necessarily cleave at the desired location. My original project was to create a mount on an existing probe station, using the station’s microscope to obtain a more precise cleaving. However, this approach has evolved into a novel method that uses a Nd:YAG laser (neodymium-doped yttrium aluminum garnet) to cleave chips, obtaining an accurate cross-section line. This trench is similar to the scratch that would have been produced by a diamond scribe in that it directs the crack as the chip is broken. However, unlike the imprecise diamond scribe, the Nd:YAG laser station is mounted on a Mitutoyo FS60 microscope which allows the user to make a burn line with great precision. After the burn line is made, the chip can be broken in the same way as in the traditional scratch and break method.

Jiufu Lim
Affiliation: Department of Physics
Advisor: Prof. Michael Lieberman (EECS)

In a vacuum diode, electrons are "boiled" off a hot cathode at zero potential, and accelerated across a gap to the anode which is held at a positive potential V. The space charge that builds up from the cloud of moving electrons reduces the field at the surface of the cathode to zero. The current and voltage relationship is then governed by the Child-Langmuir Law.

As the applied voltage increases, the current will increase until at a certain voltage, defined as the ionisation potential, the argon gas that was previously inactive in the tube become ionised by energetic electrons. At this point, positive ions exist inside the tube and neutralises the space charge. This will then give a dramatic rise in current for a further increase in voltage.

A cylindrical diode using an 884 gas triode is wired as shown in the schematic below, to be used to confirm the ionisation potential of argon to be 15.76 V, and experimentally determine the constant K and charge-to-mass ratio of the electron.

Janos Tobias Locsei
Affiliation: Department of Mechanical Engineering and Department of Physics
Advisor: Prof. Michael Lieberman (EECS)

This project aims to use cavity perturbation techniques to measure fluctuations in electron density in unstable, low pressure, inductive discharges with electronegative gases.

It would be of great benefit to the semiconductor industry to be able to control plasma instabilities. Plasma assisted steps total approximately one third of all steps in semiconductor manufacturing. For plasmas using electronegative gases, instabilities may arise in which the plasma fluctuates between inductive and capacitive modes. For the purposes of plasma assisted materials processing, it is desirable to minimise such instabilities. To this aim we must collect more data in order to understand the factors governing the instablities.

The data currently existing on plasma instabilities is incomplete. Measurements have been done in the past using electrostatic probes to determine how the electron density fluctuates with time in an unstable plasma, but for low densities these measurements are inaccurate.

This project aims to use cavity perturbation techniques to measure the electron density in the low density regime, giving a more complete picture of density fluctuations. Also there should be a region of overlap between the electrostatic probe results and the cavity perturbation results, from which we may evaluate the accuracy of each by how well they agree.

The principle of cavity perturbation is that a plasma introduced into a cavity, such as the Transformer Coupled Plasma Source (TCPS) chamber in the ERL plasma lab, will alter the resonant frequency of the cavity. For small perturbations, the change in resonant frequency is proportional to the electron density in the plasma. By measuring the change in resonant frequency it is then possible to determine the electron density. This technique has been applied to stable plasmas in the past but this is the first application to an unstable plasma.

Results so far on test setup with a mercury vapour discharge tube are proof of concept that frequency shifts can be measured using either a rasterised display with swept frequency, or just a single frequency.

Thus it remains to transfer the setup to the actual unstable plasma in the TCPS, take measurements, and compare them with theoretical predictions and electrostatic probe results.

Marc Oman and Valerie Peters
Affiliation: Department of Industrial Engineering & Operations Research
Advisor: Prof. Lee Schruben (IEOR)

Basic Linear Programming (LP) and discrete-event-simulation Event Graphs are introduced. LP’s value in understanding the dynamics of a (G/G/1) queue is illustrated. The potential role of an LP’s dual variables in determining waiting time gradients is discussed.

Colin Stuart
Affiliation: Department of Mechanical Engineering
Advisor: Prof. Werner Goldsmith (ME)

This research constitutes the inauguration for artificially altering the momentum exchange for a pre-assigned target area subjected to normal striker impact. This involves reducing the strength of a predetermined region around the contact point to produce a plug area substantially larger than the bullet cross section, achieved by cutting conical grooves of circular shape into a plate placed on a ballistic pendulum and producing central impact by a powder gun. Targets of 6061-T6 aluminum, 1/4-in thick, were struck by hard-steel, cylindro-conical, ½-in diameter projectiles of L/D = 3.

Several Regimes of striker/target interaction were found that depended on striker initial velocity, and groove depth and diameter. Speeds near 150 m/s produced neither penetration nor plugging, with frequent ricochet. Higher velocities generated plugging with ricochet or subsequent bullet passage, perforation with and without plugging. A phenomenologically interesting scenario involved plugging with an encapsulated striker.

*Abstract submitted for acceptance to the 2000 International Congress of Theoretical and Applied Mechanics (ICTAM)

Doonyapong Wongsawaeng
Affiliation: Department of Nuclear Engineering
Advisor: Prof. Donald Olander (NE)

The national weapons program and reactor development programs over the past six decades have generated sizeable amounts of radioactive waste. One type of these wastes is called "mixed" because it contains potentially toxic organic substances as well as radioactive species, such as uranium. The preferred method of disposing of these wastes is by incineration or other high-temperature processes which are intended to break down the toxic components to relatively harmless gases, reduce the volume of the waste and immobilize the radioactive species as stable oxides (e.g. UO₂). However, there have been some concerns regarding the safety of the incineration method because of the potential for release of radioactive species with the exhaust. Uranium is known to form volatile compounds with some organic materials and it may also become attached to aerosol particles and achieve volatility. Thus, the purpose of this study is to determine the characteristics of uranium volatilization in the presence of organic material under conditions relevant to the thermal treatment of mixed waste.

Simulated mixed wastes were prepared by combining uranium and an organic resin. The waste was treated in an incineration process know as pyrolysis and the exhaust was condensed and collected on silicon chips. The samples were irradiated in a reactor in order to activate any uranium by neutron absorption. Following activation, gamma-ray detection was performed and the fraction of uranium volatilized from the waste was determined. The fraction released at 600^oC is between 20 and 650 PPM and it drops to 50 PPM at 800^oC.

Walter Yu
Affiliation: Department of Civil Engineering
Advisor: Prof. Robert Bea (CE)

Risk Assessment and Management in CEM
(Construction Engineering and Management)

This poster/project discusses the interaction and importance of a risk assessment and management program within CEM. Although many contractors and builders have a risk assessment and management system, it may not be fully developed or properly enforced. This project gives a brief discussion on the field of CEM, then narrows its scope into risk. It gives the proper development and enforcement of a full risk assessment and management program. It also covers other issues related in risk and gives a brief case study.