Engineering Commons^™

Gate-Induced G-Factor Control And Dimensional Transition For Donors In Multivalley Semiconductors, Rajib Rahman, Seung H. Park, Timothy B. Boykin, Gerhard Klimeck, Sven Rogge, Lloyd Cl Hollenberg

Birck and NCN Publications

The dependence of the g factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin-based quantum computation and in semiconductor spintronics. The donor g-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and is strongly influenced by the band-structure and spin-orbit interactions of the host. Using a multimillion atom tight-binding framework, the spin-orbit Stark parameters are computed for donors in multivalley semiconductors, silicon, and germanium. Comparison with limited experimental data shows good agreement for a donor in silicon. Results for gate-induced transition from three-dimensional to two-dimensional wave-function confinement show …

Impact Of Sacrificial Layer Type On Thin-Film Metal Residual Stress, Anurag Garg, Joshua A. Small, Xiaoguang Liu, Ajit Mahapatro, Dimitrios Peroulis

Birck and NCN Publications

In this paper we study the impact of two sacrificial layers on the final residual stress of thin gold films. In particular, we comapre a typical photoresist layer (Shipley SC1827) to single-crystalline silicon. We fabricate and measure cantilever beams on both sacrificial layers and study their residual stresses by analyzing the final displacement profile of the released beams. All samples were fabricated at the same time and under identical conditions. The study clearly shows that the induced stress on thin films is dependent on the sacrificial layer. The gold film deposited over the single-crystalline silicon shows nearly zero gradient stress …

Defining And Implementing Commutativity Conditions For Parallel Execution, Milind Kulkarni, Dimitrios Prountzos, Donald Nguyen, Keshav Pingali

Department of Electrical and Computer Engineering Technical Reports

Irregular applications, which manipulate complex, pointer-based data structures, are a promising target for parallelization. Recent studies have shown that these programs exhibit a kind of parallelism called amorphous data-parallelism. Prior approaches to parallelizing these applications, such as thread-level speculation and transactional memory, often obscure parallelism because they do not distinguish between the concrete representation of a data structure and its semantic state; they conflate metadata and data.

Exploiting the semantic commutativity of methods in complex data structures is a promising approach to exposing more parallelism. Prior work has shown that abstract locks can be used to capture a subset of …

Molecular Dynamics Simulations Of Lattice Thermal Conductivity Of Bismuth Telluride Using Two-Body Interatomic Potentials, Bo Qiu, X Ruan

Birck and NCN Publications

Two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics simulations to predict the thermal conductivity. The density-functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at …

Determination Of Size Effects During The Phase Transition Of A Nanoscale Au-Si Eutectic, B J. Kim, J Tersoff, C Y. Wen, M C. Reuter, E A. Stach, F M. Ross

Birck and NCN Publications

The phase diagram of a nanoscale system can be substantially different than in the bulk, but quantitative measurements have proven elusive. Here we use in situ microscopy to observe a phase transition in a nanoscale system, together with a simple quantitative model to extract the size effects from these measurements. We expose a Au particle to disilane gas, and observe the transition from a two-phase Au + AuSi system to single-phase AuSi. Size effects are evident in the nonlinear disappearance of the solid Au. Our analysis shows a substantial shift in the liquidus line, and a discontinuous change in the …

Observation Of Quantum-Hall Effect In Gated Epitaxial Graphene Grown On Sic (0001), T Shen, J J. Gu, Y Q. Wu, M L. Bolen, Michael A. Capano, L W. Engel, P. D. Ye

Birck and NCN Publications

Epitaxial graphene films examined were formed on the Si-face of semi-insulating 4H-SiC substrates by a high temperature sublimation process. A high-k gate stack on the epitaxial graphene was realized by inserting a fully oxidized nanometer thin aluminum film as a seeding layer, followed by an atomic-layer deposition process. The electrical properties of epitaxial graphene films are retained after gate stack formation without significant degradation. At low temperatures, the quantum-Hall effect in Hall resistance is observed along with pronounced Shubnikov-de Haas oscillations in diagonal magnetoresistance of gated epitaxial graphene on SiC (0001).

Molecular Dynamics Simulations Of Lattice Thermal Conductivity Of Bismuth Telluride Using Two-Body Interatomic Potentials, Bo Qiu, X Ruan

Birck and NCN Publications

Two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics simulations to predict the thermal conductivity. The density-functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at …

Sers In Salt Wells, G. V. Pavan Kumar, Joseph Irudayaraj

Birck and NCN Publications

We report herein a simple, inexpensive fabrication methodology of salt microwells, and define the utility of the latter as nanoparticle containers for highly sensitive surface-enhanced Raman scattering (SERS) studies. AFM characterization of Ag and Au loaded salt microwells reveal the ability to contain favorable nanostructures such as nanoparticle dimers, which can significantly enhance the Raman intensity of molecules. By performing diffraction-limited confocal Raman microscopy on salt microwells, we show high sensitivity and fidelity in the detection of dyes, peptides, and proteins, as a proof of our concept. The SERS limit of detection (accumulation time of 1 s) for rhodamine B …

Use Of Steel Slag In Subgrade Applications, Irem Zeynep Yildirim, Monica Prezzi

JTRP Technical Reports

Steel slag is a by-product of steelmaking and refining processes. In 2006, 10-15 million metric ton of steel slag was generated in the U.S. Out of the total steel slag produced in the U.S. every year, about 50-70% is used as aggregate for road and pavement construction and approximately 15-40% is stockpiled in steel plants and eventually landfilled at slag disposal sites. Since current levels of steel slag stockpiling and landfilling are not sustainable, alternative geotechnical engineering applications for steel slag are being explored to alleviate the slag disposal problem and to help save dwindling natural resources. The main objectives …

Squeeze-Film Damping Of Flexible Microcantilevers At Low Ambient Pressures: Theory And Experiment, Jin Woo Lee, Ryan Tung, Arvind Raman, Hartono Sumali, John Sullivan

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

An improved theoretical approach is proposed to predict the dynamic behavior of long, slender and flexible microcantilevers affected by squeeze-film damping at low ambient pressures. Our approach extends recent continuum gas damping models which were originally derived for a rigid oscillating plate near a wall, to flexible microcantilevers for calculating and predicting squeeze-film damping ratios of higher order bending modes at reduced ambient pressures. Theoretical frequency response functions are derived for a flexible microcantilever beam excited both inertially and via external forcing. Experiments performed carefully at controlled gas pressures are used to validate our theoretical approach over five orders of …

Multicore-Aware Reuse Distance Analysis, Derek L. Schuff, Benjamin S. Parsons, Vijay S. Pai

Department of Electrical and Computer Engineering Technical Reports

This paper presents and validates methods to extend reuse distance analysis of application locality characteristics to shared-memory multicore platforms by accounting for invalidation-based cache-coherence and inter-core cache sharing. Existing reuse distance analysis methods track the number of distinct addresses referenced between reuses of the same address by a given thread, but do not model the effects of data references by other threads. This paper shows several methods to keep reuse stacks consistent so that they account for invalidations and cache sharing, either as references arise in a simulated execution or at synchronization points. These methods are evaluated against a Simics-based …

An Error Bound For The Sensor Scheduling Problem, Wei Zhang, Jianghai Hu, Michael P. Vitus

Department of Electrical and Computer Engineering Technical Reports

The sensor scheduling problem tries to select one out of multiple available sensors at each time step to minimize a weighted sum of all the estimation errors over a certain time horizon. The problem can be solved by enumerating all the possible schedules. The complexity of such an enumeration approach grows exponentially fast as the horizon increases. In this report, by introducing some numerical relaxation parameter, we develop an efficient way to compute a suboptimal sensor schedule. It is shown that by choosing the relaxation parameter small enough, the performance of the obtained suboptimal schedule can be made arbitrarily close …

Mapping Donor Electron Wave Function Deformations At A Sub-Bohr Orbit Resolution, Seung Park, Rajib Rahman, Gerhard Klimeck, Lloyd Cl Hollenberg

Birck and NCN Publications

Quantum wave function engineering of dopant-based Si nanostructures reveals new physics in the solid state, and is expected to play a vital role in future nanoelectronics. Central to any fundamental understanding or application is the ability to accurately characterize the deformation of the electron wave functions in these atom-based structures through electric and magnetic field control. We present a method for mapping the subtle changes that occur in the electron wave function through the measurement of the hyperfine tensor probed by Si-29 impurities. We calculate Stark parameters for six shells around the donor. Our results show that detecting the donor …

Evaluation Of Regression Ensembles On Drug Design Datasets, M. Fatih Amasyali, Okan Ersoy

Department of Electrical and Computer Engineering Technical Reports

Studies on drug design datasets are continuing to grow. These datasets are usually known as hard modeled, having a large number of features and a small number of samples. The most common problems in the drug design area are of regression type. Committee machines (ensembles) have become popular in machine learning because of their high performance. In this study, dynamics of ensembles on regression related drug design problems are investigated on a big dataset collection. The study tries to determine the most successful ensemble algorithm, the base algorithm-ensemble pair having the best / worst results, the best successful single algorithm, …

Optically Induced Electrokinetic Patterning And Manipulation Of Particles, Stuart J. Williams, Aloke Kumar, Steven Wereley

Birck and NCN Publications

The ability to easily and dynamically control fluid mo- tion as well as manipulate particles in suspension is impor- tant for the development and characterization of a variety of lab-on-a-chip processes. Recently, we have introduced an op- tically induced electrokinetic technique termed rapid electro- kinetic patterning (REP) that can rapidly concentrate, trans- late, and pattern colloids of many different sizes and compositions. We have tested polystyrene, latex, and silica beads in sizes ranging from 49 nm to 3.0 um.1,2

Graphene Formation Mechanisms On 4h-Sic(0001), Michael Bolen, Sara E. Harrison, Laura B. Biedermann, Michael A. Capano

Birck and NCN Publications

Graphene is created through thermal decomposition of the Si face of 4H-SiC in high-vacuum. Growth temperature and time are varied independently to gain a better understanding of how surface features and morphology affect graphene formation. Growth mechanisms of graphene are studied by ex situ atomic force microscopy (AFM) and scanning tunneling microscopy (STM). On the route toward a continuous graphene film, various growth features, such as macroscale step bunching, terrace pits, and fingers, are found and analyzed. Topographic and phase AFM analysis demonstrates how surface morphology changes with experimental conditions. Step-bunched terraces and terrace pits show a strong preference for …

Graphene Formation Mechanisms On 4h-Sic(0001), Michael Bolen, Sara E. Harrison, Laura Biedermann, Michael A. Capano

Birck and NCN Publications

Graphene is created through thermal decomposition of the Si face of 4H-SiC in high-vacuum. Growth temperature and time are varied independently to gain a better understanding of how surface features and morphology affect graphene formation. Growth mechanisms of graphene are studied by ex situ atomic force microscopy (AFM) and scanning tunneling microscopy (STM). On the route toward a continuous graphene film, various growth features, such as macroscale step bunching, terrace pits, and fingers, are found and analyzed. Topographic and phase AFM analysis demonstrates how surface morphology changes with experimental conditions. Step-bunched terraces and terrace pits show a strong preference for …

Methods For Calculating Coronary Perfusion Pressure During Cpr, Michael P. Otlewski, Leslie A. Geddes, Michael Pargett, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Coronary perfusion pressure (CPP) is a major indicator of the effectiveness of cardiopulmonary resuscitation in human and animal research studies; however methods for calculating CPP differ among research groups. Here we compare the 6 published methods for calculating CPP using the same data set of aortic (Ao) and right atrial (RA) blood pressures. CPP was computed using each of the 6 calculation methods in an anesthetized pig model, instrumented with catheters with Cobe pressure transducers. Aortic and right atrial pressures were recorded continuously during electrically induced ventricular fibrillation and standard CPR. CPP calculated from the same raw data set by …

Innovative Contracting Manual, Bob Mccullouch

JTRP Technical Reports

No abstract provided.

Design And Applications Of Drilled Displacement (Screw) Piles, Prasenjit Basu, Monica Prezzi

JTRP Technical Reports

Drilled displacement (DD) piles (commonly known as „screw piles‟ in Europe) are being increasingly used as foundation elements for structures, particularly in projects requiring accelerated construction or involving the rehabilitation of foundations of existing, overstressed structures. Different types of DD piles are available in practice; each type is classified according to the design of the drilling tool and associated installation method. Installation of DD piles causes substantial changes in the state of the soil surrounding the pile. These changes result from the complex loading imposed on the soil by expansion of a cylindrical cavity to make room for the specially …

Automated Vehicle Location (Avl) For Road Condition Reporting, Bob G. Mccullouch, Michelle Leung, Wonjin Kang

JTRP Technical Reports

This project developed an AVL system for INDOT that utilized the statewide wireless network, SAFE-T. This option was chosen after doing a cost analysis of commercial AVL systems that use cellular data communications. The system developed provides real time information collected during snow and ice removal. Information includes weather and road conditions, truck speed, amount of chemicals spread, time, location, plow position, and road temperature. This information is displayed on INDOT GIS maps available through a browser on the INDOT network. The data is also transferred to the MDSS that INDOT uses in winter activities. This system experienced significant data …

Classification Of Organic Soils, Pao-Tsung Huang, Mital Patel, Maria Caterina Santagata, Antonio Bobet

JTRP Technical Reports

The presence of organics in soils is generally associated with high compressibility, significant secondary compression, often unsatisfactory strength characteristics, and low unit weight. As a result of the above, many state DOTs (Departments of Transportation) in the United States have strict limits on the maximum value of the organic content (2-7%) that can be present in soils to be used as sub grades and backfills. The loss on ignition test is the most widely used technique for measuring organic content. However, especially for low organic content soils, this method can lead to significantly overestimate the true organic content. As a …

Worker Injury Prevention Strategies, Carlos A. Ferreira-Diaz, Alma Torres-Zapata, Christopher A. Nanovic, Dulcy M. Abraham

JTRP Technical Reports

As the trend of increased highway construction and/or rehabilitation continues to grow, the public often demands that delays in work zones be kept to a minimum. Thus, the flow of traffic through the construction zone must be maintained while performing pavement maintenance/ repair/ reconstruction activities. At the same time, the safety of personnel and property in highway construction work zones must be ensured. Three types of risks are encountered by construction and maintenance workers in construction workzones: (a) risks due to underprotection or lack of protection against potential hazards (including lack of hearing protection, eye protection, respiratory protection); (b) effect …

Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger

Other Nanotechnology Publications

The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes …

Online Piece-Wise Linear Approximation Of Numerical Streams With Precision Guarantees, Hazem Elmeleegy, Ahmed Elmagarmid, Emmanuel Cecchet, Walid G. Aref, Willy Zwaenepoel

Cyber Center Publications

Continuous “always-on” monitoring is beneficial for a number of applications, but potentially imposes a high load in terms of communication, storage and power consumption when a large number of variables need to be monitored. We introduce two new filtering techniques, swing filters and slide filters, that represent within a prescribed precision a time-varying numerical signal by a piecewise linear function, consisting of connected line segments for swing filters and (mostly) disconnected line segments for slide filters. We demonstrate the effectiveness of swing and slide filters in terms of their compression power by applying them to a reallife data set plus …

Self-Supporting Nanowire Arrays Templated In Sacrificial Branched Porous Anodic Alumina For Thermoelectric Devices, Kalapi G. Biswas, Hatem El Matbouly, Vijay Rawat, Jeremy L. Schroeder, Timothy D. Sands

Birck and NCN Publications

Templated synthesis of thermoelectric nanowires in porous anodic alumina (PAA) have potential for enhanced performance relative to bulk materials. A significant challenge is the template material, which can serve as a thermal shunt. In this work, an approach for creating a branched PAA template is described. The process utilizes localized self-heating to destabilize the planar anodization front, yielding branched and interconnected pores growing at a rate of 300 mu m/h. The template is selectively etched after electrodeposition of desired materials, yielding self-supporting nanowire arrays with thicknesses up to about 300 mu m, thereby eliminating the thermal shunt through the template.

Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad H. Weiner, Gerardo Morell

Birck and NCN Publications

In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions (TEEDs) from nanocrystalline diamond (NCD) films in the temperature range from 700 to 900 degrees C that reveal a consistent effective work function …

Diversity And Strain Specificity Of Plant Cell Wall Degrading Enzymes Revealed By The Draft Genome Of Ruminococcus Flavefaciens Fd-1, Margret E. Berg Miller, Dionysios A. Antonopoulos, Mark Brand, Albert Bari, Alvaro Hernandez, Jyothi Thimmapuram, Bryan A. White, Marco Rincon, Harry J. Flint, Bernard Henrissat, Pedro M. Coutinho

Cyber Center Publications

Ruminococcus flavefaciens is a predominant cellulolytic rumen bacterium, which forms a multi-enzyme cellulosome complex that could play an integral role in the ability of this bacterium to degrade plant cell wall polysaccharides. Identifying the major enzyme types involved in plant cell wall degradation is essential for gaining a better understanding of the cellulolytic capabilities of this organism as well as highlighting potential enzymes for application in improvement of livestock nutrition and for conversion of cellulosic biomass to liquid fuels.

Thermionic Emission Energy Distribution From Nanocrystalline Diamond Films For Direct Thermal-Electrical Energy Conversion Applications, Kishore Uppireddi, Tyler Westover, Timothy Fisher, Brad Weiner, Gerardo Morell

Birck and NCN Publications

In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions (TEEDs) from nanocrystalline diamond (NCD) films in the temperature range from 700 to 900 °C that reveal a consistent effective work function of …

Stable And Reproducible Electronic Conduction Through Dna Molecular Junctions, Ajit K. Mahapatro, Gil Lee, Kyung J. Jeong, David B. Janes

Birck and NCN Publications

This letter presents the observation of stable and reproducible electronic conduction through double stranded (ds) DNA molecules in a nominally dry state. Stable conduction was realized by immobilizing 15 base-pair guanine:cytosine rich dsDNA within gold nanogap junctions, stabilizing the dsDNA with a polycation, and characterizing in nitrogen. In air, the current levels decrease with successive voltage scans likely due to oxidation of the guanine bases under bias. In nitrogen, reproducible current-voltage traces are observed and the current levels at specific bias points are stable with time. The stability allows comprehensive electrical studies and could enable conductance-based DNA sensors.