# 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.50.00.B0814: Optimal Packings of Subspaces

**Fickus, M.**

**(937) 255-3636 x4513**

In various applications including coding theory, quantum information theory, and compressed sensing, the following problem arises: how should we arrange a given number of subspaces (of a given dimension) of a Hilbert space (of some other given dimension) so that the minimum distance between any two of these subspaces is as large as possible? That is, what are the optimal packings in the corresponding Grassmannian manifold? In the special case where the subspaces are lines (i.e., are one-dimensional) it suffices for them to form an equiangular tight frame (ETF). More generally, when the dimension of the subspaces is greater than one, equi-chordal tight fusion frames (ECTFFs) give packings that are optimal with respect to chordal distance, while equi-isoclinic tight fusion frames (EITFFs) are optimal with respect to spectral distance.

This project focuses on these ideas and other closely related concepts. Research priorities include: (1) explicit constructions of new ETFs, ECTFFs and EITFFs; (2) the discovery of new necessary conditions on the existence of such objects; (3) explicit constructions of collections of subspaces that are optimal packings in situations when no ETFs/ECTFFs/EITFFs exists (e.g., subspaces that meet the orthoplex bound); (4) applications of these ideas to other mathematical fields (e.g., combinatorial design, where certain types of ETFs are closely related to strongly regular graphs, difference sets, balanced incomplete block designs, generalized quadranges, distance regular covers of complete graphs, and association schemes); (5) design of ETFs/ECTFFs/EITFFs that meet other, real-world-application motivated constraints.

### SF.50.01.B4576: Data Analytics for Additive Manufacturing

**Badiru, A.**

**(937) 255-3636 x4799**

Successful development and deployment of additive manufacturing (AM) products require efficient and effective data analytics to transfer product characteristics to manufacturing software to drive the operations of a 3D Printer. This research involves data modeling of component shapes, characteristics, and/or profiles. The end goal of this research is to use systems engineering models and techniques to design additive manufacturing products that can meet rigorous assessment metrics for intricate product design, evaluation, justification, and integration. This research will support the activities of the Additive Manufacturing Laboratory at AFIT. The transition from traditional manufacturing to additive manufacturing calls for innovative data analytics techniques. Researchers participating in this topic must have strong analytical skills, math modeling background, software capabilities, and an interest in systems simulation. It is expected that the outputs from the research will contribute to the AFIT goal of driving and advancing innovation in new product development for defense applications.

### 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**

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, and TLAS 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 high temperature effects of film cooling of turbine vanes. These investigations have focused on attempting to understand the impact of temperature on the properties of the coolant and how cooling effectiveness results scale from low temperature investigations to high temperatures. A single vane facility exists that can change the freestream temperature from ambient to 1600K. Investigations into both internal and external cooling configurations are possible over a range of Reynolds numbers and blowing ratios.

Keywords: Combustion, Diagnostics, Novel Combustors, Film Cooling, Turbines

### 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.**

**(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.

### SF.50.18.B0001 - Networks / Security / Critical Infrastructure Protection / Applied Machine Learning / Remote Sensing

**Hopkinson, K.**

**(937)255-3636 x4579**

Our lab conducts research efforts involving Network Optimization, Network Security, SCADA / Critical Infrastructure Protection, Cognitive Radios and Cognitive Radio Networks, Applied Machine Learning, and Remote Sensing. The main goal is to use situational awareness, acquired via distributed sensor information, to enhance operations and security. Our applied machine learning work looks to advance beyond existing algorithms via machine learning in cases where we have or can acquire enough data to train effectively.

### SF.50.18.B0002 - Applications of Algebraic Number Theory to Combinatorial Designs

**Bulutoglu, D.**

**(937)255-3636 x4704**

Let X be an N by N matrix of +-1s, where N is not divisible by 4. Hadamard's maximum determinant problem seeks to find X that maximizes the value of Det(X^TX). Such an X is called a D-optimal design. The current state of knowledge on D-optimal designs is tabulated on the webpage:

http://www.indiana.edu/~maxdet/.

Finding achievable upper bounds for Det(X^TX) is essential in finding D-optimal designs. The best known upper bounds for Det(X^TX) are the Barba bound for N=1 (mod 4), Ehlich/Wojtas bound for N=2 (mod 4), and Ehlich bound for N=3 (mod 4).

Det(X^TX) is the product of eigenvalues of X^TX, where each eigenvalue is an algebraic integer in R. The first part of this research will use the approach of Cheng [1978. Optimality of certain asymmetrical experimental designs. Ann. Stat. 6, 1239-1261] and the properties of algebraic integers to improve the aforementioned best known upper bounds for Det(X^TX).

Let l be an odd integer. Binary Legendre pairs of length l can be used can be used to construct a Hadamard matrix of size 2l+2 Fletcher, Gysin, and Seberry [2001. Application of the discrete Fourier transform to the search for generalized Legendre pairs and Hadamard matrices. Australas. J. Combin. 23, 75-86]. Let

z_1k=u_0+u_1w^k+u_2w^2k+...+u_(l-1)w^(l-1)k, and

z_2k=v_0+v_1w^k+v_2w^2k+...+v_(l-1)w^(l-1)k, where

w is a primitive l'th root of unity and {u_i} and {v_i} are binary sequences of length l. Then binary Legendre pairs exists if and only if the system

|z_1k|^2+|z_2k|^2=(l+1)/2 for k=1,2,...,l

has a solution. The number of solutions to this system of equations appears to grow exponentially Fletcher, Gysin, and Seberry [2001. Application of the discrete Fourier transform to the search for generalized Legendre pairs and Hadamard matrices. Australas. J. Combin. 23, 75-86]. Both z_1k and z_2k are sums of roots of unity in a cyclotomic field extension of Q. The second part of this research will focus on exploring ways of exploiting properties of sums of roots of unity to find binary Legendre pairs for l>=49. In particular, theory of cyclotomic field extensions may be useful in studying this problem.

### SF.50.18.B0003 - Imaging Fast Neutron Sources Using Rotating Scatter Masks

**Bevins, J.**

**(937)255-3636 x4767**

This research aims to assess the feasibility of using preferential angular scattering of fast neutrons to image fast neutron source locations in mixed (gamma and neutron) radiation fields. This will be accomplished by 1) developing a nearly-optimal model of the system using the MCNP radiation transport software 2) bounding the theoretical source localization characteristics using known nuclear data uncertainties and covariances, and 3) developing initial response functions using MCNP for select neutron sources and detection geometries. The outcome of this research will determine optimal material composition, density, and geometry for development of a neutron rotating scatter mask (RSM) and develop the basis for experimental validation of the RSM's response matrix.

### SF.50.19.B0001 - Spacecraft Rendezvous and Proximity Operations

**Johnson, K.**

**(937)255-3636 x4285**

The faculty, graduate students, and staff of AFIT's Center for Space Research and Assurance (CSRA) conduct research to deliver space capabilities needed by the Department of Defense and the Intelligence Community.

Joint Publication 3-14 (joint doctrine for space operations) establishes three principles related to spacecraft rendezvous and proximity operations (RPO). First, spacecraft RPO are critical to the maneuver, protection, and sustainment of space assets. Second, in the event of hostile action against US space systems, defensive operations could include maneuver of on-orbit assets. Third, disaggregated and distributed space systems may be more resilient against threats to space operations.

A Summer Faculty Fellow will work with the CSRA to advance the state-of-the-art in the following research areas:- models for the dynamics of spacecraft RPO and distributed satellite formations (astrodynamics, modeling and simulation)

- techniques for orbital engagement maneuvers (optimal control, differential games)

- control and navigation for RPO and satellite formation flying (optimal control, relative navigation, adaptive estimation with uncertain parameters)

### SF.50.19.B0002 - Development of Optimized Methodologies for Ra

**Bevins, J.**

**(937)255-3636 x4767**

This research aims to develop and/or employ optimization methods coupled to radiation transport codes to solve problems of interest to the defense and nuclear communities. The research will employ the use of Dakota, Coeus, and/or custom optimization software coupled with MCNP and or GEANT to address design challenges. The use of these codes will be used to explore the development of integral nuclear data benchmarks, improve efficiencies for radio-isotope production targets, design optimal radiation detection imaging systems, and/or develop custom neutron spectra for technical nuclear forensics applications; each of these areas are on-going research efforts with unanswered questions. Additional opportunities to develop inverse solution methodologies for complex problem spaces related to the above research efforts also exists. The research requires computational background and experience with HPCs, but it does not require direct knowledge of the codes mentioned or radiation transport in particular. The outcome of this research will be optimized solutions and methods to address one or more of the above listed research efforts.

### SF.50.19.B0003 - Numerical Simulation of Nonlinear Waves

**Akers, B.**

**(937)255-3636 x4522**

This research program develops new asymptotic and numerical methods for the study of nonlinear wave phenomena. Numerical methods which are both flexible to problem type and highly (or spectrally) accurate are of interest. Both dynamic and steady state problems are to be considered.

These numerical methods will be developed for general problems as well as tailored to application area. Two application areas of interest are interfacial fluid dynamics and high energy laser propagation. In the former, bifurcation and stability will be research themes. In the latter, there is opportunity to coordinate with ongoing modeling and experiment.

### SF.50.19.B0004 - Novel Orbits for Military Space Mission Design in a Multi-Body Environment

**Hess, J.**

**(937)255-3636 x4713**

The faculty, graduate students, and staff of AFIT's Center for Space Research and Assurance (CSRA) conduct research to deliver space capabilities needed by the Department of Defense and the Intelligence Community.

High-altitude parking orbits provide resiliency to the military space infrastructure by providing redundancy in key assets, allowing for rapid reconstitution of underperforming satellites, both individual and formations. Novel orbits and their associated dynamics can be exploited to provide unique trajectories and designs unobservable in lower-order models. Mission design and CONOPS development in a multi-body dynamical environment may be essential to maintaining space superiority and responsiveness and securing the ultimate high ground.

A Summer Faculty Fellow will work with the CSRA to advance the state-of-the-art in the following research areas:

- investigate high-altitude orbits as a means for formation reconstitution

- construct open-loop optimal guidance policy in a dynamical environment using heuristic and pseudospectral methods

- provide alternative tactics in orbital engagement scenarios requiring finite and/or impulsive maneuvers

- investigate relative satellite motion in a multi-body dynamical environment

- evaluate the merits of high-altitude orbits for the purpose of space surveillance

### SF.50.19.B0005 - Nonlinear Structural Analysis

**Palazotto, A.**

**(937)255-3636 x4599**

the research is to design and analyze a small structure that has an internal vacuum. Both static and dynamic analysis must be carried out. Manufacturing considerations are important and must be considered. Propulsion of the vehicle is a requirement.

### SF.50.19.B0006 - Detection System Fusion

**Oxley, M.**

**(937)255-3636 x4515**

The USAF has many detection systems used for surveillance. In many scenarios these detection systems have sensors that collect Radio-Frequency (RF), electro-optic (EO) and infrared (IR) data. Combining these data (or processed data) together to improve the detection of an object-of-interest is the concept of data fusion. This problem is easy to state but is difficult to attain the predictive value of the system, due to the multiple ways to combine the RF, EO and IR detection systems. Also, these systems have parameters that can be varied. What is needed is a way to consider all possible combination rules and then determine which one(s) is optimal with respect to the detection accuracy (or the predictive value). But, this implies we would have to (1) build each combination, (2) use truth data to obtain the best parameters, (3) test the resultant combined systems, (4) validate the combined systems, then (5) determine which one is optimal with respect to the objective function, i.e., detection accuracy or predictive value (or possibly some other objective.) Mathematical theory exists for approximating these results without having to do steps 1, 2, 3, or 4. The results of this research with be of great use to the USAF and other DOD organizations, since it will help determine the best combination given the specific objective function without having to build it, train it, test it, and validate it. Once the "best" combination of the detection systems has been determined, now we know which ONE to build, train, test, and validate. This will save time and money.

### SF.50.19.B0007 - Self-tuning, Robust Estimators with Accurate Uncertainty Outputs

**Taylor, C.**

**(937)255-3636 x4614**

State estimation lies at the heart of most dynamic or reasoning systems. As these systems have become more complex, state estimators have advanced from the early Kalman filter implementations to estimators that handle larger and more complex state vectors (including mixed discrete and continuous states), accept significantly non-linear dynamic and measurement models, and handle more complicated probability distributions.

In addition to these improvements in estimators, we are particularly interested in new estimation algorithms and approaches that address the following problems:

1. Estimators that produce accurate uncertainty estimates. Much work on making better estimators has focused on computing the most accurate state estimate possible given the observed data. In many applications though, the uncertainty associated with that state estimate is of equal import to the state estimate itself. Therefore, we are interested in improvements to estimation algorithms that yield more accurate uncertainty estimates of the estimated state. One area of particular interest are computer vision algorithms where the inputs have large number of outliers. While algorithms have long been used to screen out these outliers, these algorithms’ effects on the uncertainty outputs of the estimators is not well understood or characterized.

2. Self-tuning estimators that can adjust to different uncertainties on the input signals. For example, a navigation estimator that takes in both GPS (global positioning system) and inertial measurement unit (IMU) inputs is typically tuned to the performance of a specific IMU. However, even when an IMU of the same series is put into the system, its measurements may have different uncertainty characteristics than the unit that the GPS/IMU estimator was tuned for. This can have significant effects on the performance and uncertainty estimates of the estimation system. Therefore, we are interested in estimation approaches that can self-tune to the uncertainty characteristics of the inputs, providing more accurate state and uncertainty estimates.

3. Robust estimators that can detect and appropriately handle conflicting or erroneous data. While uncertainty in the inputs is generally expected with estimators, minimum squared error estimators are significantly affected by outliers. Estimators that recognize erroneous inputs and discard them in principled ways are of significant interest.

The goal of this research is to enable theoretical or applied improvements to estimation systems, with an emphasis on one or more of the areas described above.