Research

Mesut E. Baran, Alex Q. Huang, Subhashish Bhattacharya, Pam Page Carpenter
07/01/10 - 06/30/13

North Carolina State University will develop and implement an accelerated, professional Master of Engineering degree to educate the next generation electric power engineering workforce (which includes engineers, innovators, entrepreneurs, and industry leaders) who will be ready to move into leadership positions within the electric power industry and facilitate the transformation of the current power system into a national, clean-energy smart grid. The proposed program, Master of Engineering in Electric Power Systems (ME-EPS), is an innovative program which will give students a thorough understanding of the tools, methods, and practice of electric power engineering through an intensive educational experience directly applicable to an industry career. The degree will be suitable for a recent graduate, as well as experienced professionals seeking retraining to change careers or enhanced training to expand their career opportunities.

The proposed ME-EPS program will fill a critical need for electric power industry engineering staff development, as its courses will be carefully targeted to meet specific industry needs identified by a thorough needs assessment. The ME-EPS program goal is to provide a comprehensive professional graduate degree that encompasses a broad treatment of the engineering, management, and profession skills needed in industry. Hence, this new program is fundamentally different from other degree programs and professional "short courses" currently offered. The program will consist of a set of integrated courses that will cover both core power engineering topics, as well as new cross-disciplinary technical topics relevant to the clean-energy smart grid. The program integrates four main components:

i) Core power engineering topics integrated into three courses: Fundamentals of Power Engineering, Power System Operation and Control, and Power Distribution System Operation and Management.

ii) Cross-disciplinary courses for smart grid applications. These will be totally new courses not available in current engineering programs: Electric Power Generation; Power Electronics and Its Power System Applications; Communication and Cyber Security Systems for Smart Grid; and Distribution Systems and Smart Grid Applications.

iii) Hands-on-Experience on Smart Grid Applications: Each course will have a lab or a project to provide hands on experience. To further promote integration of concepts and provide hands on experience, there will be a capstone project.

iv) Professional Skills Training: To complement the engineering training and provide professional skills, the program will include three integrated courses: The Business of the Electric Utility Industry, Engineering Economics and Project Management, and Professional Skills.

The proposed program will be an intensive 10-month program to be taught in three sessions: a one month summer session focusing on fundamentals of power engineering, and two regular fall and spring semester sessions each with five classes. Thus, the second major outcome of the project will be the large number of engineers to be trained through this program with the skills urgently needed by the power sector. The proposed program will train and educate three cohorts of students averaging 20, 30 and 50 in Years 1 to 3, respectively. The graduates of this innovative program will be highly sought after in the industry which will be facing severe engineering shortages in the near future.

This project is sponsored by US Dept. of Energy (DOE).

Nadia A. El-Masry, Salah M. Bedair
10/01/07 - 09/30/11

The objectives of proposed research are to investigate the effects of the built-in polarization field upon the FM and optical properties of GaN crystals doped with a magnetic dopant such as manganese or a rare earth element. Two main tasks are involved in this effort: (a) diffusion of magnetic dopants into polar and non-polar GaN surfaces, and (b) in situ magnetic doping during growth of III-nitride thin films on non-polar GaN surfaces. Following incorporation of the dopant, magnetic and optical properties of the GaN samples are to be characterized and assessed for spintronic device application. Correlation of these properties with the polar orientation of the GaN crystals is expected to lead to a better understanding of the physical mechanisms underlying FM behavior in III-nitride semiconductors.

This project is sponsored by US Army - Army Research Office.

Salah M. Bedair, John R. Hauser
09/01/11 - 08/31/14

We propose to reduce the current cost of multijunction (MJ) solar cells by developing a robust tunnel junction (TJ) to connect the various sub-cells. This TJ is capable of operating at high solar concentration (~2000?e) with high peak current and minimal voltage drop across the TJ.

Tunnel Junction Problems and Proposed Approaches:

1) The properties of as-grown tunnel junctions (TJ) deteriorate due to high temperature exposure, during the growth of the middle and top cells, which make the MJ structure not suitable for high solar concentration.

Approach: Insert diffusion barriers and modify the band structure at the junction interface.

2) Fluctuations in the TJ properties due to non-uniform doping levels and the variation in the concentration optics affect the performance of the MJ solar structure.

Approach: Increase excess current by the manipulation of impurities in the highly doped films.

This project is sponsored by US Dept. of Energy (DOE).

Salah M. Bedair, Nadia A. El-Masry
05/01/08 - 04/30/12

The first cascade multiple junction solar cells reported by Bedair (1979) was based on AlGaAs/GaAs for the top and bottom cell with 16% conversion efficiency. Recent progress based on three junctions cell: GaInP(1.85eV)/GaAs(1.42eV)/Ge(0.67eV) with conversion efficiency ~32% and 40% at one sun 240x, respectively was reported.

It has been realized that conversion efficiency ?0 > 35% and > 45% at on e sun and high x respectively can be achieved in four junction structure. The four junction cell requires materials system with band gap Eg: 1.9 eV/1.5 eV/1.0 eV/0.67 eV(Ge). Material system with Eg > 1.43 eV and lattice matched to GaAs (or Ge) are readily available such as InGaP (Al), GaInAsP and AlGaInAs. However, material system that collects photons in the 1.42 eV to 1.0 eV range and lattice matched to GaAs (or Ge) had proven to be very difficult to achieve.

We propose a new sub cell structure to collect photons in the energy range 1.4 ? 1 eV. This sub cell will be part of four junction cascade structure. The projected practical efficiency is in the range from 35% to 40% at one sun AM1.5 and ?0 = 45% - 50% at higher solar concentration. NCSU will develop the new sub cell and Spectra Lab will integrate the developed sub cell into their four junction structures.

This project is sponsored by US Dept. of Energy (DOE).

Subhashish Bhattacharya
07/30/10 - 07/29/13

1. Attend and actively participate in yearly workshops involving all consortium universities presenting our experiences and new developments to the other participants.

2. As much as possible, disseminate the UMN curriculum to other regional universities, technical and community colleges.

3. Submit a brief quarterly progress report to the University of Minnesota who will provide an online form for the report.

This project is sponsored by University of Minnesota.

Xiangwu Zhang, Subhashish Bhattacharya
02/09/09 - 07/31/12

This proposed work focuses on i) the development and deployment of advanced lithium-ion batteries that outperform the state-of-art batteries and ii) the design of a flexible & scalable digital power management system that integrate advanced batteries and solar cells into small satellites.

This project is sponsored by University of Florida.

Subhashish Bhattacharya, Alex Q. Huang, Mesut E. Baran
06/25/11 - 06/24/12

This project proposes to develop and deploy a distributed fast voltage regulation system to accommodate high penetration of renewable generation. The specific objectives of this project are to produce an integrated power electronics system for the objective of providing fast voltage regulation, with a specific emphasis on the speed of response required to respond to grid disturbances under high penetration of fluctuating and intermittent Distributed Energy Resources (DERs). We plan to develop and demonstrate a solution which makes it economical to place distributed Dynamic VAR Compensator systems (DVCs) throughout the distribution grid, in order to improve efficiency, power quality and stability for Smart Grid distribution systems and ultimately support a transition from centralized voltage regulation to distributed regulation. In addition, this project will develop distribution system algorithm that will allow improved and controllable voltage profiles within all voltage regulation zones of the distribution grid. Implementation of the algorithm would enhance interoperability between the fast DVC and existing (slower) voltage control devices (such as LTCs, voltage regulators and power factor correction capacitors) allowing higher penetration of DERs and possible micro-grid operations.

This project is sponsored by Varentec, LLC.

Jim C Chang
03/01/10 - 02/29/12

IPA Agreement: no abstract required

This project is sponsored by US Army - Research Laboratory (ARL).

Mihail Devetsikiotis
12/22/10 - 06/30/12

The recent proliferation of High Definition video services and Mobile applications has led not only to an increase in the demand for bandwidth for broadband access networks, but also to the need for new Service Delivery Architectures. Internet Service Providers (ISPs) are now looking on how to reengineer their broadband access infrastructure to accommodate intelligent aggregation and optimize

for QoS sensitive services. The goal is to build service-rich, cost effective and robust environments that would be extremely scalable, but also versatile enough, to accept the transformations resulting from the introduction of emerging traffic and usage patterns [1]. The main challenges include nonstop delivery, service flexibility, policy management and reduced risk. For this reason, we try to identify the appropriate architectural approach and sizing model for the aggregation network, based on the next generation traffic patterns.

More specifically, we will focus on investigating the degree of ?centralization?, single-edge vs. multi-edge characteristics, and degree of clustering. Input parameters include the emerging traffic and usage patterns, geographic distribution of sources and destinations, connectivity of the social networks involved, spatial statistics, all in addition to the temporal characteristics such as degree of self-similarity and burstiness.

This project is sponsored by Time Warner Cable (TWC).

Brian Allan Floyd
03/01/11 - 02/28/14

The large available bandwidth and/or the small wavelengths at millimeter-wave(mmWave) frequencies make possible large-volume applications such as 60-GHz communications, 77-GHz radar, and 94-GHz imaging. Within these applications, there are requirements to either steer a beam around an obstruction (60 GHz) or focus energy in a specific direction (77/94 GHz); therefore, mmWave phased-arrays in silicon is an important and growing commercial research area. Critical work remains related to power reduction of the array elements and cost-effective test, both to be pursued in this project. First, significant power reduction is needed for the phased arrays to make them viable in battery-powered devices or to reduce heat-sinking requirements. Second, since test can dominate overall cost, built-in-self-test techniques must be developed for the phased array to reduce the time of test of a complete array, to reduce the need for mmWave test equipment, and to enable phased-array manufacturing test at both wafer and package-level. In this project, a low-power 60-GHz four-element phased-array transmitter prototype with built-in-self-test will be developed in 0.12-ìm SiGe BiCMOS technology and then scalable test techniques will be developed for this demonstration platform which are applicable to 60-GHz radios, 77-GHz radars, 94-GHz imagers, and even >100-GHz sensors.

This project is sponsored by University of Texas - Dallas.

Paul D. Franzon
11/01/09 - 10/31/12

Design miniature 3D systems.

This project is sponsored by University of California - Berkeley.

Xiangwu Zhang, Alex Q. Huang, Peter S. Fedkiw, Saad A. Khan
09/16/09 - 08/15/12

The objective of the proposed work is to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously have high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure also allows the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers are electrospun into nonwoven fabrics with thickness of 50 ìm or more, and then directly used as anodes in a lithium-ion battery. This will eliminate the presence of non-active materials (e.g., conducting carbon black and polymer binder) and result in high energy and power densities. The nonwoven anode structure also provides a large electrode-electrolyte interface and, hence, high rate capacity and good low-temperature performance capability.

This project is sponsored by US Dept. of Energy (DOE).

Dennis H. Kekas, Peng Ning, Mladen A. Vouk, Rudra Dutta, Laurie A. Williams, Mihail L. Sichitiu, Michael A. Rappa, John C. Bass
04/03/08 - 11/30/13

North Carolina State University (NCSU), led by the Department of Computer Science and the Institute of Advanced Analytics in conjunction with the Institute for Next Generation IT Systems (ITng), will create and manage a Science of Security Lablet (SOSL) research organization on behalf of the National Security Agency (NSA).

This project is sponsored by US Army - Army Research Office.

Ki Wook Kim
11/01/09 - 10/31/12

As a member of the FCRP Center on Functional Engineered Nano Architectonics led by UCLA, our primary aim is to exploit novel ideas with significant potential device impacts in the newly emerging nanoengineered hybrid (or composite) structures by combining the advantages of multiferroics and semiconductors. The emphasis for semiconductors will be on atomically thin cases in a multilayered environment to facilitate nonlinear (or correlated) phenomena. Specifically, we will theoretically investigate various structures and materials in search of realizable and robust combinations for device applications. Relevant physical models will be developed and the feasibility of the underlying mechanisms in multiferroic hybrid structures examined in close collaboration with experimental groups. The application of proposed hybrid switches to memory and logic functions will be analyzed to establish the performance metrics. Device modeling will follow for the optimal design and operating conditions for experimental verification.

This project is sponsored by University of California - Los Angeles.

Ki Wook Kim
10/01/09 - 01/31/12

This research program proposes to theoretically exploit the unique properties of nanoscale graphene based structures for highly functional spintronic applications at room temperature. To overcome the non-magnetic nature of intrinsic graphene, two promising phenomena will be explored that can introduce desired spin magnetic functionalities with electrical control. The first approach attempts to incorporate the magnetism by forming a hybrid structure with appropriate magnetic materials. The interactions between graphene electrons and magnetic ions at the interfaces result in effective magnetic fields that can affect the characteristics of both graphene and magnetic layers. The second approach envisions introducing the magnetic effects by utilizing non-zero magnetic moments induced at the edge states, defects, vacancies, etc. Both of these effects are expected to be readily amenable for electrical control through the dependence on graphene electronic properties. With the development of appropriate models, the main focus of investigation is to analyze the physical properties and basic functionalization principles, particularly as the dimension of the structure shrinks, and to examine their device potential including spin magnetic switches and bio-chemical sensors. If completed successfully, the proposed research can have significant potential impacts on room-temperature carbon based spintronics, integration of magnetism with nanoelectronics, multi-functional devices, etc.

This project is sponsored by US Army - Army Research Office.

Ki Wook Kim
04/01/08 - 12/31/12

As a member of the South West Academy of Nanoelectronics sponsored by the

SRC/NERC Nanoelectronics Research Initiative, we propose to theoretically

investigate phonon/thermal transport in graphene tunneling transistors and related nanoscale devices with the ultimate goal of phonon engineering for optimum performance. Adopting a multi-scale approach, the focus of the investigation will be on accurate modeling of realistic structures with materials mismatch such as graphene/dielectric and graphene/metal interfaces.

This project is sponsored by University of Texas - Austin.

Hamid Krim, Henry J. Trussell
07/01/10 - 06/30/13

Fundamental problems in science and engineering have become increas-

ingly interdisciplinary, requiring knowledge and expert input from several

areas of research. This is both challenging and exciting. The primary chal-

lenge faced by researchers is to keep abreast of new developments in tangen-

tial research areas to their own, not to mention those which are considered

di®erent. The increasing complexity of newly arising problems has on the

other hand, invariably required a multifaceted approach to viewing and un-

derstanding them, and ultimately produce a solution.

To that end, the PIs propose to host a regularly scheduled seminar series with preeminent and leading reseachers in the US and the world, to help promote North Carolina as a center of innovation and knowledge and to ensure safeguarding its place of leading research.

This project is sponsored by US Army - Army Research Office.

Hamid Krim
03/17/11 - 03/31/12

The Missile Defense Agency is pursuing collaborative applied technology development activities with selected organizations in the Czech Republic. The projects are unclassified. They are designed to demonstrate and enhance relationships by developing technologies that are of interest to MDA. The Missile Defense Agency (MDA) funded phase 1 of a project that was conducted in partnership with the Czech Technical University (CTU) in Prague. The U.S. University was our prime contractor. A substantial portion of the effort was conducted by CTU since we were interested in their unique image reconstruction techniques. In very broad terms, our interest in MDA is in combining the images from several sensors with angular diversity into a coherent picture. While we will eventually apply the algorithms that do this to the missile defense problem (discrimination, pattern matching, etc), we are developing an approach based on the more basic techniques that the Czechs have developed in relation to more simple problems. This SOW is for a follow-on effort that would take advantage of progress made in the first year and include the continuation of basic algorithm research and process development for stereoscopic image analysis. The prime contractor is a U.S. educational institute, whose goals and purpose are more aligned to the CTU. The task will incorporate multimodal EO/IR and SAR (if available) sensor data to enhance 3D reconstruction with a focused effort on reconstructing partially obscured images using a target?s or sensor?s motion.

This project is sponsored by US Missile Defense Agency.

Hamid Krim
06/01/10 - 03/31/13

Two separate efforts are currently being pursued that could greatly benefit each other. One is the exploration of a sensing-modality (polarimetric infrared), its application to a fundamental framework (layered-sensing) and, consequently, an evaluation of that framework's utility. The second is a more "basic research" effort focused on the calculation of abstract network characteristics based in the theory of algebraic topology, a powerful computational tool. The first work, while application driven,

needs the rigor afforded by the second; the second work needs a testing ground, which the first lends itself to, naturally in many facets.

This project is sponsored by US Air Force - Office of Scientific Research (AFOSR).

Leda Lunardi, John F. Muth
09/01/08 - 08/31/11

At present, single cell and single molecule fluorescence studies have been a powerful toolset for understanding cellular processes. However, one can argue that traditional optical microscopy most of the photons are wasted with only a very small number of photons are exciting fluorophores of interest. The remaining photons are producing autofluorescence from the medium, heat within the cell and are undesirable. The goal of this portion of the project is to fabricate an array of nano-lights to create an intelligent microscope slide. By breaking the paradigm of requiring an external light source to propagate through the microscope, the nano-light emitters will be a powerful new tool for investigating cell/surface interactions and performing selective area fluorescence studies of individual cells. In addition to acting as nano-light sources for fluorescence excitation, we can also build intelligence into the nano-lights by constructing using peptides/protein binding interactions to mediate a surface plasmon resonance effect that in turn will alter the amount of light that is emitted from the nano-light. The three technological thrusts of this portion of the project are: Fabrication of nano-light emitters in an array format will also allow selective areas of an individual cell to be illuminated. Selective excitation of fluorophores present in specific areas of the single cell will: Significantly improve the signal to noise ratio by reducing the total amount of background fluorescence. Allow selective activation of photosensitive biomolecules in one portion of the cell while leaving other portions of cells untouched. Allow selective photoactiviated peptide synthesis in nanosized areas, rather than micrometer or millimeter scale areas as is presently done. Fabricate nano-lights where the efficiency of output is mediated by surface plasmon interactions with peptide/protein binding events. This will allow one to watch individual elements of the nano-light array to be turned on/off as the cell moves across the array. Retain compatibility with standard microscope instrumentation. The transparency of wide band gap semiconductor materials potentially allows the slide to be used with both inverted and non-inverted microscopes.

This project is sponsored by UNC - UNC Chapel Hill.

Veena Misra
08/22/11 - 08/21/12

In this proposal, we will explore novel dielectrics and ultra scaled channel lengths to achieve ultra high performance GaN devices. We will also characterize and model reliability of these devices.

This project is sponsored by US Navy-Office Of Naval Research.

Veena Misra, Mehmet C. Ozturk, Michael James Escuti
04/01/08 - 09/30/11

The use of state variables other than electronic charge offer great new opportunities for novel logic and memory approaches and can help create a new computation roadmap. Recently, domain wall logic has been demonstrated using ferromagnetic nanowires wherein all the basic logic functions needed to create any arbitrary logic circuit have been realized. This novel logic technology brings with it the possibility of low power electronics, low cost of fabrication and high density. However, a robust interface between the domain wall logic and input/output circuitry has not been established. The goal of this proposal is to integrate domain wall ferromagnetic nanowires with magnetic tunnel junctions via coupled magnetic nanostructures that can provide magnetic gain needed to drive I/O circuitry. The structure would employ stray fields and coupling between magnetic domains to flip the free layer of a magnetic tunnel junction and modulate a current. The proposed device would fill a missing link between devices in the newly emerging field of magnetic domain logic and conventional electronics.

This project is sponsored by University at Albany (SUNY).

Veena Misra
07/28/11 - 07/27/12

In this proposal, we seek to gain fundamental insight into the properties of SiC power devices with engineered high-K gate dielectrics. Specifically, we aim to achieve high channel mobility with positive threshold voltages using separate and independent control of the interface and engineered high-k dielectric layers, and understand the mechanisms that impact channel mobility.

This project is sponsored by Toyota Motor Engineering & Manufacturing North America, Inc..

Gregory N. Parsons, David E. Aspnes, Duane K. Larick, David A. Shultz, Veena Misra, Jon-Paul Maria
08/16/10 - 08/15/13

Through interdisciplinary doctoral education in Nanoscale Electronic and Energy Materials (NEEM), North Carolina State University (NC State) proposes to increase its commitment to interdisciplinary graduate training in electronic and energy materials related to nanotechnology. This interdisciplinary field comprises several areas designated by the GAANN Program as critical to national need: Chemical and Biomolecular Engineering, Chemistry, Electrical and Computer Engineering, Materials Science and Engineering, and Physics. Our goal is to enlarge the pool of U.S. citizens and permanent residents who will pursue teaching and research careers in nanoscale electronic and energy materials, thereby developing the academic and research infrastruc¬ture necessary for increasing U.S. competitiveness in this area and the basic science upon which its future success depends. Through outstanding faculty and facilities, as well as long-standing cooperative arrangements with other universities, government, and industry, NC State is uniquely situated to provide excellent graduate education in nanoscale electronic and energy materials.

This project is sponsored by US Dept. of Education (DED).

Gregory N. Parsons, Orlin D. Velev, Veena Misra, Christopher B. Gorman, Michael D. Dickey
07/25/08 - 07/24/13

The goal of this project is to advance fundamental understanding of novel inorganic nanostructures integrated with photoelectronic organic materials, to expand the field of nanomaterials for renewable energy devices and systems.

This project is sponsored by US Dept. of Energy (DOE).

John F. Muth, Leda Lunardi, Robert M. Kolbas
01/15/09 - 12/31/12

This project continues development of a multiwavelength light emitter to be incorporated into health monitoring applications designed by Valencell Inc.

This project is sponsored by Valencell Inc..

Afsaneh Rabiei, Steven Christopher Shannon, Mehmet C. Ozturk, Mohamed A. Bourham
09/01/10 - 02/29/12

This is to request funding to purchase and install a new Ion Beam Assisted Deposition unit and house it at the NCSU Nano-Fabrication facility.

This project is sponsored by US Dept. of Energy (DOE).

Rudra Dutta, Mihail L. Sichitiu
06/16/09 - 12/31/11

This proposal proposes to build an outdoor wireless mesh testbed comprised of a large number of low-cost experimental fabricated nodes and a small number of commercially available nodes. The testbed will be built in two stages: in the first stage, nodes placed on pushcarts will be temporarily placed outdoors for trials and tests; in the second phase, permanent antenna placements will be installed on equipment poles over a large area of the Centennial Campus of North Carolina State University. The testbed will leverage experience of, as well as enable the research of NCSU researchers participating in the Secure Open Systems Institute (SOSI), currently engaged in DoD, NSF, and other projects. Current and envisaged research activities of SOSI researchers address secure and redundant routing, energy-efficient routing, topology control, localization, cross-layer optimization, security and performance of SIP and VoIP, secure virtualization of network and compute resources, social networking. The proposed testbed will provide realistic large-scale outdoor wireless network environments for evaluating and validating the ideas, protocols and systems conceived from these activities. The data and experience gained from operating and managing a real network environment will also provide practical insights for students and researchers on the operation of large-scale heterogeneous mesh networks that help identify new security and performance problems and develop their practical solutions.

This project is sponsored by US Army - Army Research Office.

Wesley E. Snyder, Wenye Wang
08/12/11 - 08/11/14

Access control and user authentication are key elements for protecting information systems. Access control and protection from the insider threat has been identified as one of the most significant issues in information assurance. In many Army missions, keyboards and card readers may not be available; however, the soldier may be using a hand-held communication device with a touch-sensitive screen. In such a scenario, drawing a simple sketch is likely to be the most efficient and effective mechanism for access control. The soldier in the tactical environment will be provided with an easy-to-use, high reliability access control mechanism.

The text-based password has been a longtime mechanism for users to gain access to

information system such as computers or network access. However to maintain security, users have been burdened with stringent password rules, such as password length and the use of special characters. Multiple passwords for different systems and frequently expiring passwords make the use the passwords a nightmare for many users. This frequently results in security risks, as users write their passwords down and use the same password on many systems. To overcome the burdens of password systems, the authors propose to develop a novel method for computer-access security, allowing the user to draw a simple sketch as his/her password. In this project we will develop a new sketch recognition algorithm, based on the PIs prior successful work in shape recognition. The new sketch based password system will be implemented and evaluated.

The user desiring access (referred to as the artist hereafter), will draw a sketch on a

digitizer pad or touch-sensitive screen (e.g. iPad). The sketch will be matched to a data base of sketches. The principal innovation of the proposed algorithm is treating the sketch as a function of time, and using local measures of that function as parameters for the shape-recognition algorithm, SKS.

This project is sponsored by US Army - Army Research Office.

Wesley E. Snyder
10/01/11 - 06/30/12

This project will provide a biologically-plausible explanation for some gestalt

phenomena observed in the human visual system. This exploratory STIR project will limit itself to examination of straight-line detection, but it seeks an explanation for the detection of long lines which extend across a significant portion of the visual field, may be partially occluded, and may not pass through the fovea at all. This work should lead to a better understanding of non-local sensing, particularly in the visual system.

This project is sponsored by US Army - Army Research Office.

Michael B. Steer
06/01/10 - 05/31/12

The annual Workshop on Audio Technologies is sponsored by the Office of the Chief Scientist and by the Army Research Office in March or April of each year. This project is for the support of the fifth workshop in the Washington, DC area. The aim of the workshop is providing the intelligence community an exposure to the state-of-the-art audio-related technologies, and also exposure the academic community to areas of concern to the community.

This project is sponsored by US Army - Army Research Office.

Michael B. Steer, Hamid Krim, Mohammed A. Zikry, David Schurig
08/01/10 - 07/31/13

This project will develop the basic science of acoustic and electromagnetic interactions leading to the engineering of new sensors that can exploit the knowledge that these interactions provide about the environment. Stand-off probing of surface and buried objects using acoustic probes is complicated by the poor knowledge of nonlinear and diffusive acoustic effects. Great insights, including differentiation of objects, can be obtained by exploiting nonlinear acoustic interactions and by exploiting long-tail effects resulting from acoustic diffusion inside an object. The overall concept is to develop the fundamental knowledge enabling the development of a tricorder-like device for interrogating the environment thus contributing to total situational awareness

This project is sponsored by US Navy-Office Of Naval Research.

Michael B. Steer, Kevin Gard
07/01/05 - 08/31/11

This supplemental proposal accelerates the transition of signal modeling and measurement technologies to Army facilities. Technologies proposed herein are targeted for transition to the Army Research Laboratory (ARL) and the Intelligence and Information Warfare Directorate (I2WD). The impact will be broader and address the need for that part of battlefield monitoring concerned with the interaction of fields and electronics. We will research, develop and deploy a simulation environment for modeling the interaction of electromagnetic signals and circuits. Signal processing technologies will be adapted to extract information from scattered returns and in-circuit signals. Parameterized models of systems will be developed. Novel strategies for parallelizing the circuit simulation effort will be explored. Coupled with these activities will be the realization of small ruggedized instrumentation for detecting small signals in the presence of large signals.

This project is sponsored by US Army - Army Research Office.

Robert J. Trew, Ki Wook Kim
08/23/10 - 08/22/13

As a member of the research team led by the University of Arkansas, we will investigate electronic transport in graphene nanostructures for potential applications to high frequency (terahertz) sources and interconnects. Detailed theoretical models will be developed and multi-scale numerical simulations conducted to elucidate the unique advantages and fundamental limitations of this emerging material system. The obtained physical characteristics of graphene based nanostructures will be applied to devise and optimize advanced terahertz device concepts. Experimental demonstration will be pursued in collaboration with the team members.

This project is sponsored by University of Arkansas.

Robert J. Trew, Ki Wook Kim
05/19/09 - 11/19/12

This research program proposes to explore the feasibility of engineering thermal radiation for application to thermal energy harvesting. The approach is to utilize the high energy density stored in the evanescent field of surface excitations present on a thermal source composed of a polar semiconductor, by transforming it into spectrally and/or spatially selective radiation for ready extraction. At nanoscale distances, near-field thermal excitations of polar semiconductors occupy narrow bands at THz frequencies. These excitations, in the form of surface waves, establish a quasi-coherent, evanescent field with high energy density. Properly designed surface microstructures can convert the power available in evanescent modes to propagating modes with high efficiency. The proposed effort is directed towards advancements in a theoretical model that can be used to both (1) investigate and develop an understanding of the fundamental physical mechanisms associated with the phenomenon, and (2) serve as an aid in designing experiments that can be used to verify the phenomenon, as well as serve as a guide to optimizing device structures. Various test structures will be fabricated and tested in order to verify the theoretical predictions and demonstrate the feasibility of engineered thermal emission. A number of rectification schemes will also be investigated for harvesting the enhanced thermal radiation in the THz frequency and eventually converting it to the dc energy.

This project is sponsored by US Army - Army Research Laboratory.

Robert J. Trew, Griff L. Bilbro
03/14/08 - 04/30/13

This project is directed towards the development of mathematical models for AlGaN/GaN HFETs that can be used to investigate physical phenomena that affect both short term and long term reliability. Physical processes are modeled and used as a basis to explain reliability issues.

This project is sponsored by University of California - Santa Barbara.

Wenye Wang
02/09/09 - 07/31/12

The objectives of the project will be achieved by evaluating the technology for single-hop communication links, including an investigation of both radio and laser options. The study will also create mobility models based on link path dynamics. At the end of project, we will deliver 1) report on down selection of inter-satellite communication link technology, with proof-of-concept demonstrations. 2) Small satellite communications-based mobility model ; 3) Network routing protocol with accompanying performance analysis

This project is sponsored by University of Florida.

Vincent Chiang, Ronald R. Sederoff, Hou-min Chang, David C. Muddiman, Cranos Williams, Fikret Isik, Joel J. Ducoste, Christopher P. Smith
09/01/11 - 08/31/14

Plant cell walls are the essential components of feedstocks for biomass based liquid fuel alternatives to petroleum. The secondary cell walls of woody plants contribute greatly to biomass and are targets for improving potential feedstocks. In the application of systems biology to development of new biofuels, as in any complex biological process, predictive modeling is the central goal. We propose to use a systems approach with genome based information and mathematical modeling to advance the understanding of the biosynthesis of the plant secondary cell wall. To do this, we will use multiple transgenic perturbations and measure effects on plants using advanced quantitative methods of genomics, proteomics, and structural chemistry. The combination of quantitative analysis, transgenesis, statistical inference and systems modeling provide a novel and comprehensive strategy to investigate the regulation, biosynthesis and properties of the secondary cell wall.

This project is sponsored by US Dept. of Energy (DOE).

Weidong Zhang
06/17/11 - 03/16/14

The proposed research investigations will apply physics-based models and advanced numerical simulations to investigate the electronic and photonic properties of InAs/GaSb broken-gap heterostructures in the context of electron-injection driven light emission and lasing. The primary objective of this research is to develop fundamental insights into the electron and hole processes within a novel broken-gap interband resonant tunneling diode (I-RTD) structure that has been shown to offer potential for significant photonic emission and lasing at terahertz (THz) frequencies. This work conducted under this project will theoretically analyze the electron/hole transport and associated recombination processes and it will generate optimized heterostructure laser device designs that will be able to achieve significantly increased levels of terahertz (THz) frequency output power at relatively high operating temperatures (as high as ~102 W/cm2, above 200K). As will be explained in the proposal, the results from this academic research project will also be coordinated with experts within the U.S. Army Research Laboratory (ARL) and the U.S. Army Edgewood Chemical Biological Center (ECBC) to motivate collaborative activities that can be used to: realize the required broken-gap heterostructure material structures; fabricate the single-diode and arrayed micro-pillar laser devices; and execute testing for the output power and efficiency performance.

These research activities will make strategic use of broken-gap heterostructures to define completely new device solutions to the long-standing THz-frequency gap in source technology. The work will make refinements and optimizations to a previously conceptualized unipolar double-barrier GaSb/InAs/GaSb heterostructure device that simultaneously leverages resonant-electron-injection and interband-electrontunneling- depletion to realize electron population inversion, while at the same time mitigating the scattering effects that degrade the lasing process, so as to allow for achieving large available optical gain at very long wavelengths. Here, the broken-gap heterostructures allows for bringing into close proximity a population of upper-state electrons (i.e., that are confined within the double-barrier conduction-band well) with a population of lower-state holes (i.e., that are confined within the right GaSb valence-band well). The resulting key innovations are the depopulation of the valence-band well by ultrafast heavy-hole interband tunneling (i.e., time constant < 100 ps) which creates and maintains the spatial heavy-hole charge accumulation in the right GaSb barrier region by greatly outperforming the electron-filling caused by nonradiative scatterings (e.g. optical phonon and Auger).

Hence, this basic physical phenomenon suggests that powerful and tunable laser diodes are achievable, and the research proposed here seeks to apply physics-based modeling (e.g., multiband Kane model formalism) to define device structures (i.e., both double-barrier and cascaded structures) that will yield large optical gain at very long wavelengths. In addition, the interband photon emission naturally occurs in TE mode, which offers engineering advantages as compared to the familiar inter-subband quantum cascade laser which produces TM mode lasing. Specifically, the TE polarization allows for implementing the InAs/GaSb diode as a vertical-cavity surface emission laser (VCSEL), and does not require complex circuitry. Hence, this project will also define and investigate VCSEL type architectures that utilize arrays of InAs/GaSb quantum micro-pillars to mitigate thermal effects due to large drive currents so as to realize much large output powers and power efficiencies. The planned research will prescribe designs for the material hetero-layers, device geometries and cavity arrays that will be needed for realizing an optimized solid-state source for operation around 1 THz. This research effort will leverage collaborations with the U.S. Army Research Laboratory for achieving the required materials growth and devi

This project is sponsored by US Army - Army Research Office.

Weidong Zhang
10/01/11 - 07/31/12

The objective of this research is to explore the development of first principal and hybrid first principal quantum mechanical/molecular mechanical (QM/MM) simulation techniques that can help to discover novel bio-organic electronic functionalities and test these emerging physics-based modeling approaches in biological (bio) electronic and bio-chemical scenarios and sensing applications. More specifically, this research will focus on studying molecular conformations, electronic structure of ground and excited states, dynamics of bio-molecular systems and nanostructures that have relevance to future electronic systems and bio-chemical applications of interest to the U.S. Army and U.S. Department of Defense. This project seeks to support the development of novel functionality including portable, light-weight nano-sensors of bio-warfare or chemical threat agents to be used on a battlefield. For example, a sensing material using functionalized DNA origami panels as unit cells is envisioned where target-molecule- induced change in the tensor dielectric function produces a measurable diffraction of a wave transmitting through the material. Also, the scientific exploration in this project will be directed toward a research of fundamental mechanisms of stem cell growth with the goal to identify opportunities for novel medical treatments with regenerative capabilities for injured military and civilian personnel that have a potential to dramatically improve outcomes.

This project is sponsored by US Army - Army Research Office.

Weidong Zhang, Peiji Zhao
05/01/07 - 12/31/11

The double-barrier resoant tunneling diodes with staggered band alignments can admit significant interband tunneling current in addition to conduction band electron transport. This research seeks to develop multi-band models for understanding of basic transport physics of I-RTDs when subjected to magnetic fields and when composed of diluted magnetically-ordered type II superlattices. Here magnetically ordered I-RTDs refers to the situation where a small percentage of sublattice cation sites from one or two heterostrucutre layers are substitued by Mn magetic ions, which carry localized magnetic moments. The exchange coupling between conduction and valence-band electrons of a semiconductor with strongly localized substutional Mn d electrons inside a magnetic field may be significient. Therefore spin dependent tranport equation sets are derived by decoupling the total (at least six-band) Hamiltonian into ?spin-up? and ?spin-down? subsets where both Zeeman splitting and strong sp-3d exchange interaction are included in both. The objectives of this research are: (1) to calculate the resonant conduction-band current and interband Zener tunneling current; and (2) to study the nanoscale feedback dynamic processes arising from interband tunneling and its accompanied space charge accumulation. Therefore, these investigations will develop new models and execute simulations to analyze and engineer specific DMS device configurations suitable for a two-phase charging-discharging THz oscillator and explore other possible applications such as spintronics.

This project is sponsored by US Army - Army Research Office.