U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

U.S. Air Force Summer Faculty Fellowship Program

AFIT Wright Patterson AFB

SF.50.00.B5157: Chemical, Nuclear, and Biochemical Measurements and Computations Applied to CBRN Objectives

Burggraf, L.W. (937) 255-3636 x4507

Experimental and theoretical methods of chemical physics are applied to CBRN proliferation problems. Three projects illustrate the wide range of research interests: (1) characterization and inactivation of Ba and Bt bacterial spores, (2) surface chemistry of uranium oxides and contaminant metals (3) gamma imaging using Compton backscatter and gamma absorption.

We have demonstrated that topological images and phase images and chemical force measurements using atomic force microscopy (AFM) can distinguish surface properties of living and inactivated spores of bacillus anthracis from closely related bacterial spores. We are developing dynamic models of these nano-mechanical AFM measurements. We apply AFM techniques and other techniques to compare differences in properties of viable and inactivated bacillus spores. Inactivation of spores by ionizing radiation, UV radiation and thermal treatments are compared.

Uranium dioxide from nuclear fuel processes or depleted uranium munitions may be dispersed into environments. Particles of uranium dioxide react further in the atmosphere by oxidation and formation of complexes (hydrates, hydroxides, and carbonates), increasing the mobility and bioavailability of uranium, contaminant metals and fission isotopes. Spectroscopy and kinetics surface species on UO2 single crystals are measured, using spectroscopy tools including: positron spectrometry, photoluminescence (LIBS), Raman spectroscopy, Fourier transform infrared (FTIR), secondary ion mass spectrometry (SIMS), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). Spectroscopy signatures of various oxidation states and crystalline forms of uranium oxides, hydroxides, and carbonates are measured using these spectroscopy tools. Quantum methods are being developed to model spectroscopy of UxOy ions and point defects in solid state systems.

We are developing methods to employ planar high-purity germanium (HPGe) strip detectors to imaging applications including positron annihilation measurements for ACAR/DBAR and Compton/absorption gamma imaging. We are constructing a gamma spectrometer to simultaneously measure DBAR (Doppler broadened annihilation radiation) and ACAR (angular correlation annihilation radiation) spectra. We are developing a low-cost, low-bandwidth gamma imaging technique for mobile platforms using rotating scatter mask techniques. This approach is of interest for nuclear weapons inspection and field-detection of special nuclear materials using portable detectors.

SF.50.00.B5164: Chemical Lasers and Laser Spectroscopy

Perram, G.P. (937) 255-3636 x4504

Experimental research in laser physics, spectroscopy, chemical kinetics, nonlinear optics, and photochemistry form the basis for advanced laser demonstrations and development. Several technologies supported by the AFIT laser weapons research group include:

(1) Airborne Laser. The megawatt class Chemical Oxygen-Iodine Laser (COIL) is the weapon system aboard the Airborne Laser, designed to destroy theater missiles during the boost phase. AFIT has a more than 20-year history support the Air Force's high-energy laser program. Recent AFIT research in support of COIL devices include analyzing gas phase reaction rates, studying the effects of nozzle material on energy losses, and developing optical diagnostics to measure the supersonic gas temperature.

(2) Infrared Countermeasures. New, moderate power laser sources are required for electro-optic countermeasure missions such as blinding heat-seeking missiles. We are investigating photolytic gas phase laser systems and nonlinear optical techniques to develop new lasers operating in the near infrared at 3-5 microns.

(3) Remote Sensing. Space surveillance systems depend on the detection of electromagnetic radiation to interrogate the battlefield environment. Recent research activities include collecting spectral signatures from bomb detonations, examining spectral lineshapes necessary for probing meteorological conditions, and developing lasers for remote-sensing and counter proliferation applications.

(4) Optical Diagnostics. New optical methods for detecting and monitoring chemical processes are in high demand. Several examples of AFIT's activities in developing optical diagnostics include (1) assessing desorption of soil contaminants from aircraft degreasing operations, (2) studying thin-film processing from laser ablation and plasma processing, and (3) characterizing combustion chemistry. Emphasis is placed on the fundamental plume dynamics and spectroscopy in pulsed laser deposition of high-temperature superconductors to enable the manufacture of superconducting wires for aircraft power generation.

(5) Space Operations. The fundamentals of atomic, molecular, and optical physics also find application in space systems. Recent AFIT research activities include studying the photochemistry of stratospheric ozone depletion from space launch activities, examining the collisional dynamics in atomic clocks for Global Positioning System applications, and elucidating ionization mechanisms in the thermosphere for satellite survivability. Solar pumped lasers may find application for space-based missions involving long duty cycles such as de-orbiting space debris and power beaming.

SF.50.00.B5167: Molecular Reaction Dynamics

Weeks, D.E. (937) 255-3636 x4561

The detailed analysis of a wide variety of chemical reactions plays a central role in a number of Air Force and DOD applications ranging from the chemical oxygen iodine laser, to upper atmospheric chemistry, to the development of new high energy density materials. To support these efforts, we are developing new computational methods to characterize chemical reactions. Our approach employs time dependent wave package dynamics to calculate scattering matrix elements and associated reaction rates and cross sections. Initial efforts have focused on developing this new time dependent technique through the analysis of inelastic collinear reactions of type A + BC -> C, incorporating the translational and vibrational degrees of freedom. More recent efforts have successfully incorporated the rotational degree of freedom and we are currently focusing on the non-adiabatic reaction B + H2. For these calculations, we are including the rotational and vibrational degrees of freedom of the hydrogen molecule together with the electronic degrees of freedom of the Boron atom. Future efforts include the extension of the technique to four atom reactions, and the continued refinement of time dependent techniques for computing scattering matrix elements. Researchers with experience in computational physics, molecular dynamics, wave packet propagation, or related areas are encouraged to apply.

SF.50.00.B5168: Electrical, Optical, and Magnetic Studies of Various Narrow to Wide Bandgap Semiconductors

Yeo, Y.K. (937) 255-3636 x4532

Research will focus on the electrical, optical, and magnetic characterization studies of various semiconductors including group IV-IV semiconductors such as GeSn and SiGeSn, group-III nitrides such as GaN and AlGaN, II-VI semiconductors such as ZnO, and mid to narrow bandgap semiconductors such as InGaAs and InAsP for the development of infrared to blue and ultraviolet wavelength range of optoelectronic devices, high-power, high-temperature, and high-frequency electronic devices. The characterization methods include temperature dependent Hall-effect/sheet resistivity, temperature dependent current-voltage, capacitance-voltage, deep level transient spectroscopy, transmission line, photoluminescence, electroluminescence, cathodoluminescence, absorption (transmission), superconducting quantum interference device (SQUID) measurement techniques. A background in various semiconductors and their electrical, optical, and magnetic characterization techniques and in simple optoelectronic device processing techniques is desirable. This research program will contribute to an existing Air Force effort characterizing various bandgap semiconductor materials and devices.

Keywords: Wide bandgap semiconductors, Narrow to Mid bandgap semiconductors, Hall-effect measurements, Photoluminescence, Cathodoluminescence, Deep level transient spectroscopy, Superconducting quantum interference devices, Gallium nitride, Zinc oxides, Germanium tin

SF.50.00B0814: Applied Harmonic Analysis and Mathematical Signal Processing

Fickus, M. (937) 255-3636 x4513

Recent mathematical advances in the fields of frame theory and compressed sensing are revolutionizing the ways in which we measure, process and represent signals. Frame theory is the study of redundant linear decompositions, that is, how to represent a given signal in terms of an overcomplete spanning set. Frames are particularly useful in applications where traditional orthonormal-basis type decompositions are insufficient. Compressed sensing is a related field that focuses on decomposing signals which are a sparse linear combination of a large overcomplete set. It provides a mathematical formalism for justifying the intuition that low-complexity signals can be sensed with a correspondingly small number of measurements.

We are investigating several of the most challenging open problems of frame theory and compressed sensing: (1) Deterministic construction of Restricted Isometry Property (RIP) matrices and Numerically Erasure-Robust Frames (NERFs); (2) Phaseless reconstruction, that is, the design of frames that permit the reconstruction of any signal from the absolute values of its inner products with the frame vectors; (3) New constructions of Equiangular Tight Frames (ETFs) and other low-coherence dictionaries; (4) the Paulsen problem, and more generally, a better understanding of the manifold of all unit norm tight frames.

These problems have applications to remote sensing, communications, tomography, quantum information theory, and digital fingerprinting. The research itself draws inspiration from a wide variety of mathematical fields. Specializations in one or more of the following areas are particularly useful: frame theory, compressed sensing, matrix analysis, sphere packing and covering, Fourier transforms, wavelets and filter banks, algebraic geometry, algebraic coding theory and combinatorial block design.

SF.50.01.B4576: Analytical Modeling of Half-Life Learning Curves in the Defense Acquisition Lifecycle

Badiru, A. (937) 255-3636 x4799

Learning curves have been used for decades to assess improvement achieved over time due to the positive impact of learning. Early analytical modeling of learning curves focused on reduction in cumulative average cost per unit as production level doubles. Several alternate models of learning curves have been presented in the literature over the decades. The classical models have been successfully applied to a variety of problems. In recent years, the deleterious effects of forgetting have also been recognized. It has been shown that workers experience forgetting or decline in performance even while they are making progress along a learning curve. Consequently, contemporary learning curves have attempted to incorporate forgetting components into learning curves. It is of interest to study how fast and how far the forgetting impact can influence overall performance. This research introduces the concept of half-life analysis of learning curves using the concept of growth and decay, with particular emphasis on applications in defense acquisition process. Half-life is the amount of time it takes for a quantity to diminish to half of its original size through natural processes. Although the common application of half-life is in natural sciences, the computational analysis lends itself to application to learning curves, particularly for designing training programs and assessing worker performance. This is useful and desired in the Human Performance research within DOD. It is a natural process for people to learn, unlearn, and relearn. Capturing this process in a quantitative framework is essential for making effective decisions in any operation, particularly in the defense acquisition environment, where human-machine interfaces are common. Because the degradation of learning does not follow a linear path, it is essential to monitor the various stages of the learning, unlearning, and relearning processes. This research involves analytical modeling of the stage when a learning profile has degraded to half of its initial value. This is useful for predicting the magnitude and behavior of learning over time. The half-life point can be used for acquisition training and retraining purposes. With the techniques in this research, a breakeven analysis of learning can be computed because the upswing of learning and the downswing of learning conceptually intercept at some point. It is of interest to know whether that interception point occurs before or after the half-life point. For the purpose of training in acquisition operations, we can use the half-life computational technique to estimate what fraction of training retention remains after some point in time and what level of retraining might be needed during the acquisition life cycle.

Keywords: Learning curve, half-life, learn-forget models, performance, training, DOD acquisition

SF.50.01.B5171: Mission Assurance: Impact Assessment and Situational Awareness

Grimaila, M.R. (937) 255-3636 x4800

Virtually all modern organizations have embedded information systems and networking technologies into their core processes as a means to increase operational efficiency, improve decision making quality, reduce delays, and/or maximize profit. Unfortunately, this dependence can place the organization's mission at risk when an information incident (e.g., the loss or degradation of the confidentiality, integrity, availability, non-repudiation, or authenticity of a critical information resource or flow) occurs. This research focuses on developing solutions to provide decision makers with timely notification and relevant impact assessment, in terms of mission objectives, following an information incident.

SF.50.01.B6134: Combustion Dynamics for Novel Combustor Systems

Polanka, M. (937) 255-3636 x4714

As future requirements lead toward compact, efficient engine designs, conventional gas turbine component design methodology will become more integrated to provide higher performance systems. Several concepts are being explored to obtain lighter weight, more efficient, lower fuel consumption combustors. One example of this integration of components is the Ultra Compact Combustor (UCC). In this configuration, fuel is deliberately added circumferentially above the vane geometry to accomplish combustion simultaneously while the flow is turned by the vane. Research areas have focused on the combustion mechanisms at high g-loading and radial migration of the hot combustion gases into the integrated vane along with investigations into Rayleigh losses associated with higher Mach number combustion. With optical diagnostics such as PIV, PLIF, TDLAS, and CARS in place in the laboratory, the capability to completely understand these complex burning configurations exist. Future efforts will continue to understand the integration issues with the compressor and turbine. New efforts specifically geared at understanding how to cool the turbine appropriately in this high equivalence ratio environment will also be developed.

Another research area focused on the combustion process in small engines used in Remotely Piloted Aircraft. These investigations have focused on attempting to understand the impact of the inlet flow conditions, namely the altitude effects, that can impede the performance of these small IC engines. An altitude chamber has been built that enables control of the pressure and temperature within and around the engine. Investigations into fuel injection, timing, and heavy fuels are possible to understand the performance and the specific fuel consumption of the engine.

Keywords: Combustion, Diagnostics, Novel Combustors, RPAs, Internal Combustion Engines

SF.50.01.B7843: Radio Tomographic Imaging

Martin, R. (937) 255-3636 x4625

Device free localization is the process of tracking users who are not emitting a radio signal. An emerging method of doing this is radio tomographic imaging (RTI). RTI involves setting up a dense network of radio sensors. When a user physically enters the network, it will obstruct a subset of the network links. By measuring the change in signal strength on all network links, it is possible to compute a 3D image indicating which voxels are obstructed. This can in turn be used for target tracking and identification. Of particular military interest is the fact that RTI can be used for imaging through walls and foliage; for example, work at AFIT has demonstrated imaging capabilities through foot-thick concrete walls.

Current RTI research at AFIT includes (i) improving the physical model relating the presence of a user to the change in radio signal strength, while accounting for multipath, (ii) improving the performance of the imaging algorithm, (iii) improving the system implementation by reducing computations or designing an application-specific communication protocol for the sensors, and (iv) developing target tracking and identification tools.

SF.50.02.B7123: Fracture and Fatigue of Advanced Materials/MEMS

Mall, S. (937) 255-3636 x4587

Active research is in progress to characterize the deformation mechanisms, fracture and fatigue behavior for structural materials including conventional polymeric composites, high temperature composites, nanocomposites. Also, contact mechanics issues in MEMS are being investigated. We are interested in the experimental as well as modeling efforts of mechanical response of and damage mechanisms in materials under myriad of loading conditions, such as high cycle fatigue, low-cycle fatigue, fretting foreign object damage, creep, fretting, thermo-mechanical fatigue, etc. Unique experimental facilities for testing are available. Research focuses on developing the scientific base and fundamental understanding.

SF.50.13.B0821: Precision Navigation

Raquet, J.F (937) 255-3636 x4580

The Advanced Navigation Technology (ANT) Center is focused on developing robust position, navigation, and timing (PNT) solutions that enable highly accurate and very precise navigation capabilities in Global Positioning System (GPS)-denied or contested environments. To this end, the research and development (R&D) efforts of the ANT program concentrate on the following research thrusts:

• Autonomous and Cooperative Systems: Increasing autonomy and cooperation between remotely controlled vehicles to perform tasks (such and targets, mapping, etc.) more efficiently and/or more precisely

• Non-GPS Precision Navigation: Development of non-GPS technologies and integration schemes for GPS-level or better navigation and time accuracy to support precision combat in all environments. Current research efforts include using signals of opportunity such as cellular networks and wi-fi, vision and optical flow, gravimetric measurements, LiDAR, magnetic field variations.

• Robust GPS Navigation/Navigation Warfare (NAVWAR): Expansion of the GPS “operating envelope” in terms of jamming, high dynamics, and precision differential GPS, so United States military forces maintain the performance advantage of GPS over all potential adversary systems. This includes consideration to foreign global navigation satellite systems (GNSS).

SF.50.14.B1105: Small Satellite Research and Development

Swenson, E. (937) 255-3636 ext 7479

AFIT designs, builds, and tests satellites and space experiments as part of their education and research mission. As part of their STEM efforts, AFIT students and researchers designed and developed a standard 3U CubeSat that is currently awaiting launch. AFIT students and researchers are currently in the process of developing a larger and more capable 6U CubeSat. The 6U can carry larger and more capable payloads and AFIT researchers are focused on incorporating payloads that are of direct interest of the DOD. A summer fellow, with expertise in the area of satellite design and test, will not only enrich DOD officer’s and civilian’s satellite educational and development experience but also numerous local interns who will also work at AFIT over the summer. It is expected that a summer fellow would also participate in AFIT’s planning and development processes all while contributing to the various phases of construction, assembly, and testing all of which will be performed in-house. These efforts will be ultimately focused on research, design, and education with regards to DOD space payloads and satellites. The primary benefits will likely occur from the summer fellow directly interacting with AFIT students and interns throughout the entire design and build process. Additionally the summer fellow will perform research in the fields of small satellite bus and payload technology development, including, but not limited to, imaging and signals collection payloads, and power and attitude control subsystems.

SF.50.14.B1125: Biological Process Research for Environmental Applications

Harper, W. (937) 255-3636 ext 4528

My research explores biological processes that are important in a range of environmental applications, with a primary focus on water quality. Currently-sponsored projects are focused on the removal of organic chemicals, biosensing, and resource recovery. Research activity combines traditional research approaches, such as mathematical modeling and laboratory-scale experimentation, with the modern tools from chemistry and microbiology, and research based on this combination uncovers knowledge and provides exciting opportunities for interdisciplinary collaboration. Although individual projects might emphasize experimentation, modeling, or microbiological aspects, all research involves quantification, the key to making the research results relevant to engineers.

The objectives of our ongoing projects are: 1) to understand and predict the fate of chemical warfare agents and industrial chemicals in engineered water treatment systems, 2) investigate novel biosensors and hyperspectral imaging technology to detect hazardous substances, and 3) evaluate resource recovery paradigms using systems thinking.

SF.50.16.B0002 - Human Machine Interaction

Miller, M.E. (937)255-3636 x4651

We traditionally view machines as tools. However, as processing power increases, how do we design computing systems to serve as collaborative partners to improve human productivity, effectiveness, and satisfaction? My research concentrates primarily on the development of design tools and methods to aid the design of the interface between humans and man-made agents. This research includes the consideration of naturalistic interfaces, understanding human state using behavior and physiology, and agent design.

SF.50.16.B0003 - Creep Deformation and Durability of Ultra High Temperature Ceramics in Extreme Environments

Ruggles-Wrenn, M.B. (937)255-3636 x4641

The ultra-high temperature ceramics (UHTCs) are candidates for such aerospace applications as sharp leading edges and thermal protection systems for reusable atmospheric re-entry vehicles and hypersonic flight vehicles. Before UHTCs can be used in applications, their structural integrity and environmental durability must be assured. To provide that assurance, the mechanical behavior of UHTCs at relevant service temperatures and environments must be thoroughly understood and characterized. Recent research at AFIT developed, constructed and validated a unique facility for mechanical testing of UHTCs in air or argon at 1500-1700°C. We developed and validated a method to perform compression creep tests of small UHTC samples in air or argon at 1500-1700°C.

Ongoing research is focused on investigating mechanical behavior of the UHTCs at temperatures ranging from 1300 to 1700 °C in laboratory air or inert gas. We aim to provide fundamental analysis of high-temperature deformation of UHTCs and to identify the controlling creep mechanisms. It is envisioned that experimental results obtained in compression creep tests of UHTCs at 1300-1700°C in air and in argon will provide a basis for evaluating creep rates, creep activation energies, and identifying operating creep mechanisms. Emphasis is on assessing the interaction between oxidation and compression creep processes. Unknown deformation and failure mechanisms may be discovered. Results of this research will provide experimental foundation to extend the models for the oxidation of the UHTCs to include the effects of mechanical load on oxidation.

We are interested in experimental investigation as well as in modeling of the material response subjected to mechanical loading in extreme environmental conditions. Unique experimental facilities are available in the Mechanics of Advanced Aerospace Materials Laboratory (MAAML) at AFIT.

SF.50.16.B0004 - Evaluation of the Additive Manufactured (AM) Material to High Energy Impact

Palazotto, A.N. (937)255-3636 x4599

Recently it has become of interest to see if AM products have value within the aerospace environment. The research contained in this effort is to take and investigate materials made from two different origins; one is Ti 6Al-4V and the other is 15-5 stainless steel using the electron beam sintering additive manufacturing method. Specimens will be manufactured and tested in a split Hopkinson bar set-up after which the microstructure evaluated and compared at various strain rates. Modeling will also be carried out to determine the appropriate constitutive relationship for each of the materials. After the relationships have been developed, a finite element solution related to a ballistic impact will be studied.

SF.50.17.B0001 - Environmental Sensing and Modeling of Methane Emissions via Unmanned Aerial Vehicles (UAVs)

Slagley, J. (937)255-3636 x4632

Methane emissions have a devastating effect on the atmosphere. Methane has been shown a far more effective greenhouse gas than carbon dioxide. Methane emissions sensing and modeling is very important to understand source apportionment and aid in developing policies and technologies to control emissions. There are two main methods in methane inventorying and apportionment: atmospheric sampling and modeling (top down), and source sampling and modeling (bottom up). The source sampling and modeling lends itself better to apportionment, but there are disparities in taking relatively few samples and relying on ranges of assumptions in the models. More sampling data from sources refine the models, but the spatial and temporal distribution of source emissions precludes exhaustive study. It is time-consuming and expensive to have environmental scientists in the field collecting data. Unmanned Aerial Vehicles (UAVs) offer an opportunity for source emissions sampling at remote sites which extends the capacity of the field environmental scientist. However, there are several research questions to resolve to enable using the sampling data in source emissions modeling. 1. Effects of “prop wash” on sampling measurements and techniques to employ UAVs to minimize adverse effects 2. Payload tradeoff to achieve sufficient measurement resolution/limit of detection 3. Georeferencing and flight velocity/sensor response time error resolution.

SF.50.17.B0002 - Flying Qualities and Handling Qualities Assessments for Unmanned Aircraft

Kunz, D. (937)255-3636 x4548

As the roles and missions for unmanned aircraft have expanded, so has the need to assure airworthiness, in particular the flying and handling qualities. Current standards, where they exist, fail to provide guidance for RDT&E activities. The focus of this research is to develop flying qualities criteria and handling qualities methodologies that can be specifically applied to unmanned aircraft and will support RDT&E. For the purposes of this research, flying qualities are define as characteristics of the aircraft, such as frequencies, damping ratios, bandwidths, etc.; and handling qualities are defined as quantities that assess the ability of the aircraft to complete an assigned mission. Among the topics of interest are: (1) Definitions and use of metrics for the purposes of evaluating the handling qualities of unmanned aircraft: (2) Establishment of flying qualities criteria that are appropriate for unmanned aircraft; (3) Scaling flying/handling qualities for unmanned aircraft of all sizes; and (4) Investigations of other methodologies that may assist in assuring the airworthiness of unmanned aircraft.

SF.50.17.B0003 - Origami Design

Palazotto, A. (937)255-3636 x4599

Research has been carried out in the area of Lighter than air vehicles with an internal vacuum. Several structural systems have been designed that show promise in actually being built with the ability to float. I am interested in evaluating other structural arrangements beside the Icosahedrons or hexakis icosahedrons that have been worked on. The one I am particularly interested in is the Origami structure. This structure has as its primary make up a basic unit of folded plates interconnected through common boundaries. The overall shape of the structure is a spherical shell. The main goal is the design of this structure and to eventually construct it using an additive manufacture system. This shell like structure will then be tested in the mechanics laboratory under a compressive load and the results compared to a nonlinear instability analysis.