Engineering Commons^™

The Effect Of Contact Length On Adhesion Between Carbon Nanotubes On Silicon Dioxide, Robert C. Davis, Kaylee Mcelroy, Aaron R. Hopkins

Faculty Publications

The force of adhesion was measured for single walled carbon nanotubes grown over lithographically defined silicon dioxide trenches. We varied contact lengths between the nanotubes and silicon dioxide from 230 to 850 nm. Suspended nanotubes were pushed vertically into the trenches with an atomic force microscope tip, causing them to slip along the surface. Previous work done at shorter contact lengths found that tension was constant with contact length [J. D. Whittaker et al., Nano Lett. 6, 953 (2006)]. This study finds that when the nanotube contact length approaches 1 µm, the tension at which nanotubes slip begins to increase …

). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li

Faculty Publications

Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.

Transient Molecular Dynamics Simulations Of Viscosity For Simple Fluids, Richard L. Rowley, Jason C. Thomas

Faculty Publications

A transient molecular dynamics (TMD) method has been developed for simulation of fluid viscosity. In this method a sinusoidal velocity profile is instantaneously overlaid onto equilibrated molecular velocities, and the subsequent decay of that velocity profile is observed. The viscosity is obtained by matching in a least-squares sense the analytical solution of the corresponding momentum transport boundary-value problem to the simulated decay of the initial velocity profile. The method was benchmarked by comparing results obtained from the TMD method for a Lennard-Jones fluid with those previously obtained using equilibrium molecular dynamics (EMD) simulations. Two different constitutive models were used in …

Wireless Power Transmission To A Buried Sensor In Concrete, Khan M.Z. Shams, Mohammod Ali

Faculty Publications

The feasibility of sending wireless power to a buried sensor antenna within concrete was studied. a receive patch rectenna with 75.8% conversion efficiency was designed for operation at 5.7 GHz. The received DC power at the rectenna was measured within dry and wet concrete samples with various cover thicknesses and air-gaps. For the rectenna buried within 30 mm of the concrete, the received DC power was 10.37 mW, which was, about 70% of the received DC power in free-space.

Are There Rearrangement Hotspots In The Human Genome?, Max A. Alekseyev, Pavel A. Pevzner

Faculty Publications

In a landmark paper, Nadeau and Taylor [18] formulated the random breakage model (RBM) of chromosome evolution that postulates that there are no rearrangement hotspots in the human genome. In the next two decades, numerous studies with progressively increasing levels of resolution made RBM the de facto theory of chromosome evolution. Despite the fact that RBM had prophetic prediction power, it was recently refuted by Pevzner and Tesler [4], who introduced the fragile breakage model (FBM), postulating that the human genome is a mosaic of solid regions (with low propensity for rearrangements) and fragile regions (rearrangement hotspots). However, the rebuttal …

Experimental Validation Of An Autonomous Control System On A Mobile Robot Platform, Timothy Mclain, Randall W. Beard, Wei Ran, J.-S. Sun

Faculty Publications

An autonomous control system designed for a non-holonomic wheeled mobile robot that is programmed to emulate a fixed-wing unmanned air vehicle (UAV) flying at constant altitude is experimentally validated. The overall system is capable of waypoint navigation, threat avoidance, real-time trajectory generation and trajectory tracking. Both the wheeled mobile robot experimental platform and the hierarchical autonomous control software architecture are introduced. Programmed to emulate a fixed-wing UAV flying at constant altitude, a non-holonomic mobile robot is assigned to follow a desired time-parameterised trajectory generated by a real-time trajectory generator to transition through a sequence of targets in the presence of …

Polarization Rotation Correction In Radiometry: An Error Analysis, David G. Long, Derek Hudson, Jeffrey R. Piepmeier

Faculty Publications

Yueh proposed a method of using the third Stokes parameter TU to correct brightness temperatures such as Tv and Th for polarization rotation. This paper presents an extended error analysis of the estimation of Tv , Th, and TQ equiv Tv - Th by Yueh's method. In order to carry out the analysis, we first develop a forward model of polarization rotation that accounts for the random nature of thermal radiation, receiver noise, and (to first order) calibration. Analytic formulas are then derived for the bias, standard deviation (STD), and root-mean-square error (RMSE) of estimated TQ, Tv , and Th, …

Nanoindentation Of The A And C Domains In A Tetragonal Batio3 Single Crystal, Young-Bae Park, Matthew J. Dicken, Zhi-Hui Xu, Xiaodong Li

Faculty Publications

Nanoindentation in conjunction with piezoresponse force microscopy was used to study domain switching and to measure the mechanical properties of individual ferroelectric domains in a tetragonal BaTiO₃ single crystal. It was found that nanoindentation has induced local domain switching; the a and c domains of BaTiO₃ have different elastic moduli but similar hardness.Nanoindentationmodulus mapping on the a and c domains further confirmed such difference in elasticity. Finite element modeling was used to simulate the von Mises stress and plastic strain profiles of the indentations on both a and c domains, which introduces a much higher stress level than …

Cognitive Radio: Fundamentals And Opportunities., Robert H. Morelos-Zaragoza

Faculty Publications

This talk is aimed at MSEE students in San Jose State University. It provides an overview of cognitive radio concepts and technologies. A MATLAB Simulink of demonstration of digital channel selection using a low IF radio architecture is presented. Technical challenges that remain to be solved in this area are identified.

Web Site Personalization Based On Link Analysis And Navigational Patterns, Magdalini Eirinaki, M. Varzirgiannis

Faculty Publications

The continuous growth in the size and use of the World Wide Web imposes new methods of design and development of on-line information services. The need for predicting the users’ needs in order to improve the usability and user retention of a web site is more than evident and can be addressed by personalizing it. Recommendation algorithms aim at proposing “next” pages to users based on their current visit and the past users’ navigational patterns. In the vast majority of related algorithms, however, only the usage data are used to produce recommendations, disregarding the structural properties of the web graph. …

Edge Grouping Combining Boundary And Region Information, Joachim S. Stahl, Song Wang

Faculty Publications

This paper introduces a new edge-grouping method to detect perceptually salient structures in noisy images. Specifically, we define a new grouping cost function in a ratio form, where the numerator measures the boundary proximity of the resulting structure and the denominator measures the area of the resulting structure. This area term introduces a preference towards detecting larger-size structures and, therefore, makes the resulting edge grouping more robust to image noise. To find the optimal edge grouping with the minimum grouping cost, we develop a special graph model with two different kinds of edges and then reduce the grouping problem to …

Byu Wideband Mimo Channel Sounder Technical Reference Manual, Jon W. Wallace

Faculty Publications

This document serves as a technical reference manual for the wideband multiple-input multipleoutput (MIMO) wireless channel sounder developed at the Wireless Research Laboratory at Brigham Young University. The development of this system is considered an "open hardware project," which means that the details of the system may be freely used by others interested in designing and building similar systems. Also, it is hoped that the open hardware methodology will lead to fruitful cooperation in improving the system and sharing ideas.

Silicon Dioxide-Encapsulated High-Voltage Algan/Gan Hfets For Power-Switching Applications, N. Tipirneni, V. Adivarahan, Grigory Simin, Asif Khan

Faculty Publications

In this letter, new approach in achieving high breakdown voltages in AlGan/GaN heterostructure field-effect transistors (HFETs) by suppressing surface flashover using solid encapsulation material is presented. Surface flashover in III-Nitride-based HFETs limits the operating voltages at levels well below breakdown voltages of GaN. This premature gate-drain breakdown can be suppressed by immersing devices in high-dielectric-strength liquids (e.g., Fluorinert); however, such a technique is not practical. In this letter, AlGan/GaN HFETs encapsulated with PECVD-deposited SiO2 films demonstrated breakdown voltage of 900 V, very similar to that of devices immersed in Fluorinert liquid. Simultaneously, low dynamic ON-resistance of 2.43 m Omega. cm(2) …

Localization With Limited Sensing, Jason M. O'Kane, Steven M. Lavalle

Faculty Publications

Localization is a fundamental problem for many kinds of mobile robots. Sensor systems of varying ability have been proposed and successfully used to solve the problem. This paper probes the lower limits of this range by describing three extremely simple robot models and addresses the active localization problem for each. The robot, whose configuration is composed of its position and orientation, moves in a fully-known, simply connected polygonal environment. We pose the localization task as a planning problem in the robot's information space, which encapsulates the uncertainty in the robot's configuration. We consider robots equipped with: 1) angular and linear …

Experiments In Cooperative Timing For Miniature Air Vehicles, Derek R. Nelson, Timothy W. Mclain, Randal W. Beard

Faculty Publications

This paper presents experimental results for two cooperative timing missions carried out using a team of three miniature air vehicles (MAVs). Using a cooperative timing algorithm based on coordination functions and coordination variables, the MAV team executed a series of simultaneous arrival and cooperative fly-by missions. In the presence of significant wind disturbances, the average time difference between the first and last vehicle in the simultaneous arrival experiments was 1.6 s. For the cooperative fly-by experiments, the average timing error between vehicle arrivals was 0.6 s. These results demonstrate the practical feasibility of the cooperative timing approach.

Experiments In Cooperative Timing For Miniature Air Vehicles, Timothy Mclain, Derek R. Nelson, Randal W. Beard

Faculty Publications

This paper presents experimental results for two cooperative timing missions carried out using a team of three miniature air vehicles (MAVs). Using a cooperative timing algorithm based on coordination functions and coordination variables, the MAV team executed a series of simultaneous arrival and cooperative fly-by missions. In the presence of significant wind disturbances, the average time difference between the first and last vehicle in the simultaneous arrival experiments was 1.6 s. For the cooperative fly-by experiments, the average timing error between vehicle arrivals was 0.6 s. These results demonstrate the practical feasibility of the cooperative timing approach.

Obstacle Avoidance Using Circular Paths, Timothy Mclain, Randal W. Beard, Jeffery Brian Saunders

Faculty Publications

This paper develops a method of obstacle avoidance for fixed-wing miniature air vehicles (MAV) using a series of circular oscillating paths and a single point laser ranger. The laser ranger is a low power, light-weight device used to report the distance to an object in a single direction of the body frame of a MAV. The oscillating paths allow the laser ranger to scan for obstacles and possible escape paths for the MAV in the case of obstacle detection. The circular paths are generated along waypoint paths and transition between waypoint paths without loss of scanning capabilities. Obstacle avoidance is …

Potential Energy Surfaces For Small Alcohol Dimers. Ii. Propanol, Isopropanol, T-Butanol, And Sec-Butanol, Richard L. Rowley, Christopher M. Tracy, Tapani A. Pakkanen

Faculty Publications

Potential energy landscapes for homogeneous dimers of propanol, isopropanol, tert-butanol, and sec-butanol were obtained using 735 counterpoise-corrected energies at the MP2/6-311+G(2df,2pd) level. The landscapes were sampled at 15 dimer separation distances for different relative monomer geometries, or routes, given in terms of the yaw, pitch, and roll of one monomer relative to the other and the spherical angles between the two monomer centers (taken as the C atom attached to the O). The resultant individual energy surfaces and their complex topographies were also regressed using a site-site pair potential model using a modified Morse potential that provides a mathematically simple …

Bubble Dynamics Of Ultrasonic Drug Release From Polymeric Micelles, Mario A. Diaz, William G. Pitt

Faculty Publications

We have reported the ability of Pluronic P-105 micelles to sequester anthracycline drugs and release their contents upon application of 70 kHz ultrasound (US)1 (Figure 1). Optimal targeting to tumors depends on focus and control of US insonation, which is better achieved at higher frequencies. While no evidence of in vitro drug release was found at 500 kHz, drug release at 70 kHz correlates with the intensity of the subharmonic signal in the acoustic spectrum generated by the insonated bubbles2(Figure 2). Having established that bubble oscillations (cavitation) are directly related to drug release at 70 kHz, we now investigate the …

Ultrasonically-Assisted Drug Delivery In Rats Reduces Tumor Growth, William G. Pitt, Beverly L. Roeder, G. Bruce Schaalje, Bryant J. Staples

Faculty Publications

Previously we have shown that nanosized drug carriers called Plurogels™ sequestered Doxorubicin (Dox) and partially released this drug with application of ultrasound (US) (Fig. 1)1. The application to chemotherapy was successfully demonstrated in a rat tumor model2. However previous studies did not examine the distribution of Dox in the insonated and control tissue. This recent work investigated the effect of two US frequencies and examined the Dox distribution in the insonated and control tumors to determine if US was depositing more Dox at the insonated site.

Extended Abstract Rotopod: A Novel Approach To Efficient Legged Locomotion, Damian M. Lyons

Faculty Publications

A number of attempts have been made to integrate the efficiency of wheeled locomotion with the terrain versatility of legged locomotion, e.g., Univ.Michigan’s Rhex platform and Case Western’s Whegs. Those platforms cast legs as rotating spokes placed traditionally at the corners of a rectangular platform. In this paper, we present an alternate approach, with three legs radiating down from a central hub. The energy to move the platform is generated by a rotating reaction mass mounted at the hub and, at rest, rotating parallel to the ground plane.

Our approach is to construct a platform whose natural, uncontrolled motion is …

Time-Varying Mimo Channels: Parametric Statistical Modeling And Experimental Results, Michael A. Jensen, Shuangquan Wang, Ali Abdi, Jari Salo, Hassan M. El-Sallabi, Jon W. Wallace, Pertti Vainikainen

Faculty Publications

Accurate characterization of multiple-input multiple-output (MIMO) fading channels is an important prerequisite for the design of multiantenna wireless-communication systems. In this paper, a single-bounce two-ring statistical model for the time-varying MIMO flat fading channels is proposed. In the model, both the base and mobile stations are surrounded by their own ring of scatterers. For the proposed model, a closed-form expression for the spatio-temporal cross-correlational function between any two subchannels is derived, assuming single-bounce scattering. The new analytical expression includes several key physical parameters of interest such as the mean angle-of-departure, the mean angle-of-arrival, the associated angle spreads, and the Doppler …

Information Consensus And Its Application In Multi-Vehicle Cooperative Control, Ella Atkins, Randal Beard, Wei Ren

Faculty Publications

In the last two decades, advances in networking and distributed computing have facilitated a paradigm shift from large, monolithic mainframe computers to networks of less expensive, less powerful workstations. One motivation for multi-vehicle systems is to achieve the same gains for mechanically controlled systems as has been gained in distributed computation. Rather than having a single monolithic (and therefore expensive and complicated) machine do everything, the hope is that many inexpensive, simple machines, can achieve the same, or enhanced functionality, through coordination. In essence, the objective is to replace expensive complicated hardware with software and multiple copies of simple hardware. …

Vector Field Path Following For Miniature Air Vehicles, Timothy Mclain, Derek R. Nelson, D. Blake Barber, Randall W. Beard

Faculty Publications

In this paper, a method for accurate path following for miniature air vehicles is developed. The method is based on the notion of vector fields, which are used to generate desired course inputs to inner-loop attitude control laws. Vector-field path-following control laws are developed for straight-line paths and circular arcs and orbits. Lyapunov stability arguments are used to demonstrate asymptotic decay of path-following errors in the presence of constant wind disturbances. Experimental flight tests have demonstrated mean path-following errors on less than one wingspan for straight-line and orbit paths and less than three wingspans for paths with frequent changes in …

Prime Modules: Teaching Introduction To Materials Engineering In The Context Of Modern Technologies, Stacy Gleixner, Elliot Douglas, Olivia Graeve

Faculty Publications

This paper discusses the progress of curriculum development under an NSF, CCLI-EMD sponsored work, “Development of Project-Based Introductory to Materials Engineering Modules” (DUE # #0341633). A multi-university team of faculty is developing five lecture modules for use in Introductory to Materials courses. This course is required by most engineering programs in the U.S., with an annual enrollment of 50,000 students. This freshman/ sophomore class is an ideal place to excite students about their engineering majors and expose them to real world engineering experiences. PRIME Modules are being developed that teach the fundamentals of a traditional introduction to materials engineering course …

Optimization Of Nano-Magneto-Optic Sensitivity Using Dual Dielectric Layer Enhancement, Aaron R. Hawkins, J. D. Maas, S. Wang, A. Barman, Holger Schmidt, S. Kwon, B. Harteneck, S. Cabrini, J. Bokor

Faculty Publications

We discuss maximization of the sensitivity of magneto-optical detection of single nanomagnets. We show that a combination of optimized dielectric coating on the magnets with an antireflection coated substrate can increase the areal magneto-optic sensitivity by about three orders of magnitude in the deep nanometer range. A dual layer nanofabrication process is developed to implement this approach, and magnetization switching of single nickel nanomagnets with 50 nm diameter is demonstrated.

Evaluation Of A Parallel Architecture And Algorithm For Mapping And Localization, Damian M. Lyons, Giselle R. Isner

Faculty Publications

The Beowulf cluster approach to parallel computation offers a potentially cheap and robust source of computational power for high complexity algorithms in robotics. The challenge is to integrate this approach with the mobility and time critical response constraints of many robotic algorithms. The key contributions of this paper are: (1) introduction of a computational architecture for integrating a cluster into the control architecture of one or more robots, (2) a cluster implementation of Thrun et al’s Concurrent Localization and Mapping (CML) algorithm, and (3) presentation of results to illustrate the performance of the implemented CML algorithm and validate the architectural …

Assessment Of Labview And Multisim In The Delivery Of Electronics Laboratory Content, Julio Garcia, Patricia Backer

Faculty Publications

The goal of this study, funded by the National Science Foundation, was to adapt the work of other researchers to improve the delivery of electronics lecture and laboratory content in the Electronics & Computer Technology (ECT) area. From the extensive research on ethnic and gender differences in learning styles, the evidence suggests that ethnic minorities and women work best when the material is organized so that students work in teams and have a high level of hands-on experimentation and problem-solving. We developed our materials to maximize these aspects since in our institution the “minority” constitutes the majority of our student …

Technology And Gender Issues: Development And Assessment Of A Freshman General Education Course In The College Of Engineering, Patricia Backer

Faculty Publications

This class, Technology VS Women, explores the interaction of gender with technology and answers questions such as: Is technology a “male” science? Is modern technology compatible to both male and female users? What does history tell us about the role of women at work relating to technology? The ideas presented in this course challenges some commonly held myths and misconceptions about technology in our society. This course focuses on the technological changes since 1900 and how they have affected both men and women. The effect of cultural biases and perspectives on the working and educational environments also are addressed. This …

Assessment Of Multi Media & Web Based Instruction In A Science Technology & Society Course, Patricia Backer

Faculty Publications

Multimedia can be a powerful tool in exploring the nature of the world around us, including its technological systems. This paper describes the assessment of self-paced multimedia and web- based modules that are used in an advanced General Education (GE) course in the College of Engineering at San José State University. The development of these modules began in 1994 and has undergone many revisions. Currently, four of the seven units in this class are taught using either multimedia CDs or web-based material.The General Education course, Technology and Civilization (TECH 198), is designed to introduce students to the realm of history …