Our Research Projects

A Whole-Brain Ultrasonic Neural Stimulation And Photoacoustic Recording System In Behaving Animals

Omer Oralkan
09/01/2017 - 08/31/2019

This project aims to develop a 2D capacitive micromachined ultrasonic transducer (CMUT) array with integrated electronics and optics that is capable of ultrasonic neural stimulation in 3D volume by dynamic transmit beamforming and real-time recording of hemodynamic activity in response to stimulation by volumetric photoacoustic imaging. The described technology will equip the neuroscience community with a research tool to further explore the emerging field of ultrasonic neural stimulation and to monitor metabolic/hemodynamic responses in awake/behaving animals with real-time photoacoustic imaging.

Behavioral Modeling for High Speed Links, Center for Advanced Electronics through Machine Learning (CAEML) Core Project 1A5 funded with industry membership dues.

Paul D. Franzon
01/01/2017 - 08/15/2019

Modeling High Speed Links as part of the CAEML IUCRC.

SaTC: CORE: Small: Towards Smart and Secure Non Volatile Memory

Huiyang Zhou
08/01/2017 - 07/31/2020

This research investigates smart and secure technologies for non-volatile memory.

CNS: SHF: Small: Architectural Support for Efficient and Programmable Non-Volatile Main Memory

James Tuck
10/01/2017 - 09/30/2020

Non-Volatile Memory is advancing and may soon replace DRAM and disk as a unified memory and storage device. For instance, Intel and Micron announced that their 3D Xpoint memory will be in the market in 2017. This breaks the conventional view of computer systems with separate memory and storage systems, and requires that future systems be redesigned to support the new possibilities this integrate provides. One problem is that processors will be able to access storage directly using loads and stores, and current processors do not guarantee that stores update memory in the order specified by the programmer. This means that updates to memory and storage may happen out of order resulting in an inconsistent state during a system failure or power-loss. Dealing with failure-safety adds new complexity to software and additional performance overheads on these future systems.

This project will investigate new techniques that help programmers write high performing and efficient code for future systems that use non-volatile main memory. In particular, techniques that simplify programming while accelerating performance are sought. A promising direction for solving some of these problems is speculative execution. Speculation has been successfully used to make parallel programming easier and to speed up execution in the presence of long latency memory accesses. Many of the problems raised by non-volatile memory are similar to the ones that speculation has been applied to in the past. This proposal takes a systematic look at how speculative execution can make future NVM systems more efficient and more programmable.

University Leadership Initiative; Hyper-Spectral Communications, Networking & ATM as Foundation for Safe and Efficient Future Flight: Transcending Aviation Operational Limitations with Diverse and Secure Multi-Band, Multi-Mode, and mmWave Wireless Li

Ismail Guvenc
06/12/2017 - 09/29/2020

This research will address the Aeronautics Research Mission Directorate’s (ARMD’s) Strategic Thrust (ST) #1, Safe, Efficient Growth in Global Operations. The research outcomes fit within the ARMD’s Strategic Implementation Plan (SIP) years 2025-2035 and beyond 2035 time frames, and will contribute specifically to the following outcomes: (i) fully integrated terminal, enroute, surface and arrivals/departures operations (ATM+2), and (ii) fully autonomous trajectory services (ATM+3).

As is well known, air travel and air transport are expanding rapidly. Unmanned aircraft system (UAS) use is burgeoning. An obvious consequence of the growth in passenger and freight air traffic, and the coming of UAS into the worldwide airspace, is continuing growth in air traffic density and complexity. Although initially UAS will fly in airspace separate from piloted aircraft, there will inevitably come “mixed airspaces,” and likely full integration of UAS throughout the complete current worldwide airspace (and in the future, beyond, e.g., stratospheric flights). The addition of UAS will compound the already increasing complexity of air traffic management (ATM). The increase in density (aircraft per unit volume) means that safe operation will become more challenging. The situation is more complex for ATM than for terrestrial commercial communications, because of greater aircraft mobility and much more stringent reliability requirements. Since safe operation cannot take place without highly-reliable and efficient communications and networking among aircraft, ground stations, and other entities, we are proposing research to dramatically enhance the capabilities of aviation communication and networking systems. Hence, the research areas of our investigation are aeronautical communications, networking, and ATM, including aspects of navigation and surveillance, for both manned and unmanned aircraft.

Natural Variation and Systems-Level Properties of Gene Regulation in Drosophila

Gregory T Reeves, Cranos Williams
09/01/2017 - 05/31/2022

Progress Report

A Novel Three-Dimensional Thin-film Thermoelectric Generator for Wearable Applications

Daryoosh Vashaee, Mehmet C. Ozturk
08/01/2017 - 07/31/2020

An integrated research, education, and outreach program is proposed that will introduce a novel, highly efficient, photo-enhanced thermoelectric generator. The new device, which has the potential to transform the thermoelectric industry will provide > 100X improvement in output voltage compared to conventional devices. The new device achieves this performance enhancement thanks to an entirely new device architecture, which significantly reduces the parasitic losses as well as its ability to harvest both photoexcited (light) and thermoelectric (heat) carriers. The program has four main goals:
1. Device Demonstration: A CMOS compatible, wafer-scale micro-fabrication process will be developed to fabricate a highly efficient, photo-enhanced thermoelectric energy generator (PTEG) on inexpensive silicon wafers. The fabrication will rely on mature processes and techniques used in micro-electro-mechanical-systems (MEMS) integration.
2. Material Development: The work will focus on improving the material properties for room-temperature applications. A particular composition of Si(1-x)Ge(x) providing high degeneracy of the band minima (N=10) is proposed. Nanostructuring and partial amorphization of the semiconductor material will be used to further improve the figure-of-merit ZT using a novel microwave method previously introduced by the principal investigator.
3. Modeling: A comprehensive system model will be developed to optimize the device architecture. The effort will include both thermal and semiconductor modeling, which will focus on carrier transport, photoexcitation, and ambipolar diffusion.
4. A broad education plan will be developed including a new teaching initiative in the upper-division undergraduate curriculum, involvement of undergraduates in research, and outreach, with aims to introduce energy conversion materials to the general public.
Intellectual merit:
The proposed photo-enhanced thermoelectric generator has the potential to revolutionize the way the thermoelectric modules are manufactured. While this proposal focuses on energy harvesting, innovations introduced to the device architecture are also applicable to thermoelectric devices intended for cooling or infrared imaging applications. The specific material and device configuration used in this proposal has a broad range of indoor applications ranging from wearable electronics for monitoring of human health and environmental conditions to commercial systems that require self-powered, continuous and wireless monitoring. The proposed device architecture is compatible with modern thin film thermoelectric materials and manufacturing processes.
We anticipate that this research should lead to (a) discovery of new ways to harvest both light and heat energy, and (b) a competitive silicon-compatible thermoelectric material for room temperature applications. The device is particularly efficient for use with complex systems that involve sensors and electronics. Hence, it will potentially have high commercial market acceptance in emerging, self-powered, connected sensor systems. This program is a natural extension of a highly fertile line of leading research by the PIs, which has generated many publications in top ranked journals, and has been featured in both wide and specialized audience journals (Science, Nature, PRL, etc.).

Retrofit Control: A New, Modular Gyrator Control Approach for Integrating Large-Scale Renewable Power

Aranya Chakrabortty
08/01/2017 - 07/31/2020

This project will address the growing concerns of wind and solar power integration from the perspective of power system dynamics and stability. We propose a new retrofit control technique where an additional controller is designed at the doubly-fed induction generator site inside the wind power plant, or the power electronic converter models for battery satorage units that may be accompaying a wind or solar power plant. This controller cancels the adverse impacts of the power flow from the wind side to the grid side on the dynamics of
the overall system. The main advantage of this controller is that it can be implemented by feeding back only the wind states and wind bus voltage without depending on any of the other synchronous machines in the rest of the system. Through simulations carried out in our hardware in the loop testbed at the FREEDM center we plan to show how the proposed control technique can efficiently enhance the damping performance of a power system variable despite very high values of renewable penetration.

CAREER: Towards Broadband and UAV-Assisted Heterogeneous Networks for Public Safety Communications

Ismail Guvenc
09/01/2016 - 03/31/2020

The demand for wireless data communications is increasing far faster than advances in wireless communications, and at the current pace, demand will outpace the available capacity in major markets in just a few short years. To encourage innovation in the area of collaborative spectrum sharing, DARPA organized a Spectrum Collaboration Challenge (SC2) with the stated goal to develop “autonomous collaboration techniques for efficient spectrum sharing,” which aim to yield 100-1000 fold improvements in spectrum efficiency. This supplement is in support of the participation of the NCSU team (team Wolfpack) in DARPA’s SC2 challenge.

The main objective of the proposed supplement is to research, develop, and implement technical solution concepts for collaborative spectrum sharing and to test their performance in head-to-head scrimmages with other competing approaches. In particular, we will research, develop, and test spectrum sharing algorithms that build on fundamental concepts in communication theory, cognitive radios, machine learning, routing, among other technical domains. The proposed methods will also be validated in the DARPA SC2 challenge by competing against other teams, which will allow us to revise and improve our framework as needed.

Wireless communications are affecting deeply the daily lives of the overwhelming majority of people on this planet. The insatiable demand for network capacity has motivated an entirely different approach on spectrum utilization. Work in this proposal will enable new collaboration approaches that will impact the lives of anybody relying directly or indirectly on wireless communications. In addition to direct impacts, national security and public services rely heavily on wireless communications, and thus can indirectly impact the well being of all citizens.

RESEARCH AREA 4: ELECTRONICS: Reconfigurable Electrofluidic Networks for Highly Adaptive Electronic Warfare Platforms

Jacob James Adams
04/21/2017 - 04/20/2020

Military communication, navigation, and radar systems must operate in electromagnetically contested environments with high fidelity. In this environment, the ideal electromagnetic (EM) platform consists of a multi-functional (sensing, communications, electronic attack) and highly adaptive, able to generate and sense radiation across a wide range of frequencies, with controllable directional and polarization sensitivity. Among the critical needs for such “smart” radios are reconfigurable antennas that can dynamically change their radiation patterns or frequency response. Here we propose networks of liquid metal embedded in the skin of a vehicle, aircraft, or other communications/sensing platform. These electrofluidic (EF) networks are physically reconfigurable – the conductors can be moved in and out of particular channels to change the electromagnetic characteristics of the platform. The proposed work encompasses several goals towards controlling and realizing these EF networks.

Eager: Tandem Solar Cells of Two Dissimilar Material Systems

Salah M. Bedair
05/01/2017 - 04/30/2020

We propose two years research program to address the current issues of connecting two solar cells in a tandem structure. The propose approach is versatile and can be applied to several solar cell combination’s with different band gaps. It also lifts the current restrictions of lattice matching for the tandem cell components and can also be used to connect cells made of materials with different expansion coefficient.

CRISP Type 2: Collaborative Research Towards Resilient Smart Cities

Ismail Guvenc
08/15/2016 - 08/14/2019

Realizing the vision of truly smart cities is one of the most pressing technical challenges of the coming decade. The success of this vision requires a synergistic integration of cyber-physical critical infrastructures (CIs) such as smart grids, smart transportation, and wireless communication systems into a unified smart city. Such CIs have significant resource interdependencies as they share energy, computation, wireless spectrum, personnel (users, operators), and economic investments. Such resource sharing increases the proneness of such CIs to cascading failures. For example, the failure of a generator will cause a power outage for residential customers as well as an outage on portions of the wireless CI. This, in turn, can impact the platoons of vehicles connected to this communication CI. Protecting such CIs from failures requires instilling resiliency into the processes which manage their common resources. Resiliency is defined as the CIs’ ability to recover from failure by optimally allocating their resources over their nodes and connections. While there has been notable activity recently in improving the resiliency of CIs, these have been primarily motivated by singular and often catastrophic events related to weather, terrorism and other natural disasters. Also, most such efforts have been restricted to a single CI with only one interdependency between a communication and a physical component and do not explicitly account for the presence of humans that interact seamlessly with the CIs. In reality, smart cities require protecting multiple, interdependent CIs each of which is used by millions of users. The goal of this interdisciplinary research is to address this challenge by developing a holistic approach for optimizing the resiliency of a city’s interdependent CIs.

This research will lay the foundations of resilient smart cities by introducing a foundational framework for leveraging the CIs’ interdependencies to yield resilient resource management schemes cognizant of both technological and human factors. By bringing together researchers in cyber-physical systems, computer and network science, transportation engineering, security, behavioral economics, power systems, wireless networks, and psychology, this framework will yield theoretical and practical advances: 1) Rigorous mathematical techniques for delineating the interdependencies between CIs via a symbiotic mix of novel tools from graph theory, machine learning, and random spatial models; 2) Novel resilient resource management mechanisms that advance notions from powerful frameworks such as cognitive hierarchy theory, dynamic learning, and the Colonel Blotto game to enable optimized management of shared CI resources in face of failures stemming from agents of varying intelligence levels ranging from random events (wear-and-tear, natural disasters) to highly strategic attacks; 3) New behavioral models for characterizing the trust relationships between a smart city’s residents and the CIs; 4) Behavioral studies that provides guidelines on: a) how to influence the CIs’ users using communication messages conveyed over platforms to be developed and b) how such influence impacts the resiliency of the coupled CIs; and 5) Large-scale smart city simulator that exploits realistic CI data coupled with real-world experiments over four major smart grid, communication, and transportation testbeds, that will bridge the gap between theory and practice.

Distributed Energy Storage Device (DESD)

Wensong Yu, Srdjan Miodrag Lukic, & Alex Q. Huang
09/01/2016 - 08/31/2019

The overall objective of this project is to develop a bidirectional, fully functional, efficient and reliable medium-voltage SST. The prototype will directly connect to 7.2kV FREEDM transformer and provide both 380 DC and 240 AC buses.

Investigations On Current And Future 3GPP Channel Models And The Evaluation Of Various Existing MIMO Techniques With These Channel Models

Ismail Guvenc, Yavuz Yapici
08/15/2016 - 04/30/2020

This new supplement aims to extend the earlier measurements and analytical studies into metasurface reflectors. In particular, we will carry out measurements using metasurface reflectors in indoor/outdoor scenarios, and compare the performance with the case when only standard metallic reflectors are used. Frequency band of interest is 28 GHz. We aim to do measurements in the lab environment as well as outdoor settings in NCSU campus.

NeTS: Small: Collaborative Research: Towards Millimeter Wave Communications for Unmanned Aerial Vehicles

Ismail Guvenc
10/01/2016 - 09/30/2019

With the proliferation of bandwidth hungry mobile devices, dense deployments of users, and the proliferation of Internet of Things (IoT) technologies, broadband spectrum needs have been continuously increasing in recent years. The use of the millimeter wave (mmWave) frequency bands is seen as a major way to address this spectrum crunch problem since large amounts of licensed and unlicensed bandwidths are available at these frequencies, leading to new standards being developed for 5G cellular and Wi-Fi using mmWave. In parallel, there have been unprecedented recent advances in commercial unmanned aerial vehicle (UAV) technologies, which has resulted in their adoption in a wide range of applications, such as disaster relief, agricultural monitoring, wireless connectivity in rural areas, and hotspot connectivity for major sporting events.

The proposed research in this project aims to study the foundations of mmWave communications in UAVs in a systematic manner using notions from wireless networks, communication theory, optimization theory, and software defined radios (SDRs), starting from channel sounding and characterization. A key challenge in any mmWave communication is that beamforming needs to be used in order to overcome the path loss. The use of mmWave on UAVs poses additional challenges and benefits. The challenges are primarily due to limited battery life and weight carrying capability of UAVs and the benefits accrue from the use of: 1) large bandwidth; 2) ability to implement 3D beamforming enabling improved spatial reuse; and 3) harnessing the UAV mobility to perform dynamic UAV clustering and interference management. The goal of this project is to address these fundamental challenges via a unique research collaboration focused on developing the next-generation of analytical and experimental tools for designing, modeling, optimizing, and testing mmWave UAV networks. Specific areas of study will include: (i) novel precoder designs for mmWave UAVs taking into account realistic propagation characteristics derived from channel sounding experiments; (ii) equalizer design for mmWave UAVs that trade-off beamwidth against equalizer structure; (iii) multiple access design for mmWave UAVs: code division and time division multiple access techniques will be revisited for mmWave UAV communications, for serving users that are accessed by the same transmitter beam; and (iv) optimal UAV placement for multi-hop wireless backhaul: investigating the use of UAVs as flying relays.

EAGER: Exploring Extreme-Scale DNA-based Storage Systems

James Tuck, Albert J. Keung
09/01/2016 - 08/31/2019

The world’s digital data is growing rapidly and is projected to exceed 16 zettabytes (1021) in 2017. This vast amount of digital data greatly exceeds our ability to store it even when accounting for expected advances in the storage industry. We need extraordinary advances in how we store information in order to catch up.

DNA offers a potentially transformative solution due to its high raw capacity of 1 zettabyte/cm3 (1 exabyte/mm3). To put that in perspective, the best technology available today would require 100,000 cubic meters of volume(10 GB/mm3) to store the equivalent amount of information, more than 10 to the 11th power times less dense. If successful as a storage medium, DNA could hold the world’s entire digital data in a relatively small volume. Also, DNA offers unprecedented reliability. It has a very long life even in relatively harsh conditions compared to electronic media, retaining its structure for hundreds to thousands of years at room temperature.

The overall concept of DNA storage is that extreme amounts of infrequently-accessed information will be stored in DNA, and when needed, subsets of the DNA will be copied to an electronic computer system with more limited but rapid-access storage capacity.

However, DNA is a unique material with very different chemical and physical properties compared to traditional electronic storage media. Thus, the more pertinent question for computer systems experts is determining how to design a high capacity and reliable storage system using DNA given its chemo-physical properties and constraints. This project will investigate some key limitations and design choices for DNA storage systems.

Doping of Diamond and c-BN beyond Thermodynamic Solubility Limit for Solid State Devices

Jagdish Narayan, Ki Wook Kim
09/28/2017 - 09/27/2020

This research program proposes a transformative approach to n- and p-doping of diamond and c-BN beyond the current state-of-the-art. The main concept is based on the recently discovered direct conversion of amorphous carbon into diamond and h-BN into c-BN at ambient temperatures and pressures in air in the form of large-area single-crystal films on substrates such as sapphire and silicon. The key advantage stems from the novel growth method, where the carbon layers are melted by using high-power nanosecond pulsed lasers in a highly super undercooled state, and then quenched rapidly either into a new state of carbon or into the single-crystal diamond phase in the presence of a template for diamond growth. Similarly, h-BN can be melted in a super undercooled state and converted into large-area single-crystal c-BN films. Accordingly, it is envisioned that dopant impurities present in the amorphous carbon and h-BN films can be incorporated into substitutional sites of diamond and c-BN during rapid liquid-phase crystallization via the phenomenon of solute trapping. As the proposed approach is a fundamentally nonequilibrium process, dopant concentrations in electrically active sites for both n- and p-types can far exceed the thermodynamic equilibrium solubility limits, while maintaining the energy levels, overcoming the long-standing challenge of diamond.

Specifically, the feasibility studies on n-type doping (N, P, As and Sb dopants) will be carried out by incorporating these dopants into carbon by ion implantation, followed by rapid recrystallization from super undercooled state into epitaxial diamond thin film heterostructures. Similarly, n-type and p-type doping of c-BN will be achieved by Si and Zn dopants, respectively. The p-type (B dopants) doping of diamond will be accomplished by pulsed laser deposition of boron doped carbon layers at 500C in the presence of oxygen and hydrogen. Our preliminary results on nitrogen doping in diamond have already indicated that the dopant concentrations in electrically active substitutional sites can indeed be much beyond the thermodynamic solubility limits. Lattice location (substitutional versus interstitial) studies will be performed by using atomic resolution techniques and the results correlated with electrical activation and detailed carrier transport measurements. Theoretical calculations of dopant energy levels, ionization efficiencies, carrier concentrations and mobilities will be carried out in parallel to establish correlations with experimental results and to guide the fabrication of novel solid state devices. A primary goal of the combined effort is to demonstrate the p-n diodes of diamond and c-BN with satisfactory junction characteristics by controlling the dopant concentrations and the types vertically and/or laterally in the process. When successfully implemented, the proposed research is expected to revolutionize the doping and practical applications of diamond as well as the related materials such as c-BN.

Modeling and Characterization of Wideband Communications Via Narrowband Channels Using Direct Modulation

Jacob James Adams
09/15/2016 - 09/14/2019

Long distance communications rely on HF, VHF, and UHF wireless systems where wavelengths are over 1 meter long. Conventionally, resonant antennas are used in mobile applications in these bands, due to the large size required for more broadband structures. A resonant antenna in steady state can only effectively transmit a narrow range of frequencies. However, if the antenna’s properties are modulated at a rate on the order of the symbol frequency, then the antenna becomes a time variant system that may circumvent the physical limitations of small antennas. Experiments have indicated that unusually wideband emissions from small antennas are possible, though further study is needed to address the fundamental questions in this area and improve the present understanding of time-varying radiators. The overall scientific goal of this proposal is to establish models and design methodologies for radiating systems with rapidly time-varying properties.

Snapshot Imaging laser Displacement Sensor for Hypervelocity Diagnostic Testing

Michael Kudenov
09/14/2016 - 09/10/2019

Reentry and hypersonic low- and mid-altitude vehicles are subjected to significant aerothermal heating as kinetic energy is dissipated into the atmosphere. Designing a vehicle to withstand aerothermal heating and other associated aerodynamic loads poses a significant engineering challenge in materials research. In the development of materials- and physics-based models, significant testing is conducted in hypersonic wind tunnels. Deformations in a surface or material can be related to internal stresses; thus, measuring such deformations, in situ, within the hypersonic environment must be achieved without distrubing the hypersonic characteristics of the flow. This project will develop high speed optical metrology equipment, optimized for use in hypersonic wind tunnel testing.

Collaborative Research: A Visual System for Autonomous Foraminifera Identification

Edgar J Lobaton
08/01/2016 - 07/31/2019

Paleoceanography, among other research fields, depends crucially on ubiquitous ocean dwelling single celled organisms called foraminifera. Undergraduate workers are often employed to pick several thousands of specimens from ocean sediments for each study. Depending on deposition rates and abundance of the species, such manual processing can become tediously repetitive with little intellectual motivation for the undergraduate workers, and time and cost-prohibitive for research scientists. The proposed project aims to develop a completely autonomous system for visual identification of foraminifera. This system will be compatible with existing off-the-shelf microscopes, and will utilize pattern recognition tools that will be made available to the entire scientific community. This project has the potential to enable robotic systems that can perform autonomous picking of foraminifera samples.