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

AFRL/RW Eglin Air Force Base, Florida

SF.45.01.B5483: Efficient Processing of Optimally Sampled 2-D and 3-D Imagery

Rummelt, N.I.

(850) 883-0886

The hexagonal grid and the body-centered cubic (BCC) lattice are the optimal sampling lattices for isotropically band-limited 2-D and 3-D signals, respectively. These lattices provide significant improvements in sampling efficiency over traditional rectangular sampling but have not been commonly used due to inefficiencies related to their non-Cartesian nature. A recent advance in addressing such lattices promises to overcome the inefficiencies and allow for the use of these optimal sampling approaches for common image processing applications. Research is being conducted that aims to take advantage of the improved sampling efficiency of these lattices to provide significant improvements in various areas of signal processing. Research opportunities exist in the development of fundamental techniques in processing optimally sampled imagery that lead to demonstrable improvements over current state-of-the-art approaches.

SF.45.02.B7106: Meso-structure – Property – Performance Relationships in Energetic Materials

Pemberton, S.

(850) 882-1195

Manni, S.

(850) 882-0357

Molek, C.

(850) 882-9244

The loading and performance requirements on energetic materials for Air Force applications are becoming increasingly severe. Understanding of the processing – structure – property – performance relationships, particularly at the meso-scale, is critical to enable the design and use of energetic materials. Several research areas are required to develop this topic experimentally, theoretically, and computationally: non-shock and shock initiation and growth of reaction/detonation; microstructural quantification and analysis, particularly of damage; material design and formulation to enhance performance and insensitivity/survivability; pressure-strain rate-temperature dependent material properties, namely of polymers, particulate composites, and energetic materials.

SF.45.02.B7454: Agile Munition Vehicles Sciences

Pasiliao, Crystal

850-882-8809

We conduct research on the coupled interaction of fluid, structural, thermal, and material dynamics applicable to high-performance weapon airframes. The research includes multidisciplinary approaches in theoretical, computational, and experimental fluid and structural dynamics, and multifunctional materials. We specifically seek to characterize the fundamental physics dictating the overall vehicle controllability, agility, lethality, and survivability. The products of this research will lay the foundation for development of methodologies and tools to exploit the physics of agile, maneuvering weapon airframes of all size scales and speed regimes applicable to tactical weapons in transition between the three phases of flight: (1) air-launch, (2) in-transit, and (3) terminal (e.g., low Reynolds number micro-scale airframes, air-launched unitary subsonic to supersonic guided bombs, air-launched supersonic to low hypersonic air-intercept, and long-range strike weapons). Research opportunities exist in the characterization, control, and exploitation of aero, structural, thermal, and material dynamics that enhance munitions operational capability. Keywords: Fluid dynamics; Structural dynamics; Thermal dynamics; Computational fluid dynamics; Aeroelasticity; Aerothermodynamics

SF.45.02.B7604: Detonating Systems Research

Welle, E.J.

(850) 883-0581

This research will focus on the understanding of fundamental detonation phenomena. Most conventional explosive models are typically described as composite models, which means they treat a complex reacting flow system with 100 to1000’s of chemical reactions and intermediate material states as having only two. Those two states are joined by a reaction rate rule that governs how energy is liberated by moving between those states. We are conducting research to determine how to resolve such reaction pathways by going from 2 to n-number of states that allow for more useful predictive capabilities. Small scale experiment is being invented or matured to facilitate the measurement of needed material characteristics such as equations-of-state for the unreacted, partially, and fully reacted energetic materials. Typical measurement techniques include dual streak cameras, Photon Doppler Velocimetry, and high-speed imaging that can be resolved to the nanosecond or subnanosecond timescale. The work will also include assessment of conventional hydrocode based reactive flow models to determine their physical relevance to problem sets of interest. The Associate will be able to design and participate in the execution of complex optical experiments, become familiar with conventional reactive flow models, design experiments with modelers, and report work in refereed journals or conferences that are open to the general community or limited based on work content.

Keywords: Detonation; Explosive; Optical diagnostics; Equation of state; Photon Doppler Velocimetry; Shock to detonation; Thin pulse initiation; Explosive microstructure; Laser interferometry

SF.45.02.B7623: Shock Physics

C. Neel

(850) 882-7992

This research opportunity focuses on the fundamental understanding of shock physics in inert and chemically reacting systems. A persistent need remains in the understanding of material response under shock loading, specifically in the area of high-fidelity experiments and measurements. Emerging “mesoscale” modeling approaches have highlighted shortfalls in the conventional characterization methods treating the materials specimens as continuum, or homogenized fields. Current line VISAR (velocity interferometer system for any reflector), digital image correlation (DIC), and photonic Doppler velocimeter (PDV) for ultrahigh-speed image intensified cameras (IIC) and time-resolve emission spectroscopy are available for this research in quantifying the material states of impact shock-loadings. The research will emphasize new opportunities and capabilities in characterizing (both analytically and experimentally) the mesoscale constituent response of heterogeneous and particular materials. A broad range of material systems are considered for this research, including specific geomaterials and soils to nanoparticle reactive materials capable of rapid self-oxidation, to high-energy explosive compositions. We are interested in the broad range of research topics, which include new equations of state, improvements to existing EOS descriptions and models, improved diagnostics or implementations of existing, and advancing our understanding of the constituent response at mesoscale and how to link that response up through the macro-level responses. This research will rely heavily on the interactions between numerical simulation, experiment, and theory with the primary goal of drawing each to comparable fidelity and common basis of comparison.

Keywords:

Shock; Hugoniot; Equation of state; Detonation; Mesoscale; Interferometry; Particulate mechanics;

 

SF.45.03.B5434: Network Optimization and Control

Pasiliao, Eduardo

850-883-2563

Research is in progress on the cooperative control of air armament designed to detect, identify, and attack ground targets. Although many cooperative system approaches model the uncertainty of the environment, they fail to address risks associated with poorly specified stochastic models of the environment, the adversary, or the cooperating agents. Cooperative agents must optimize "local" objectives that ideally translate into achieving global or collective objectives. Because information gathering and decision-making are distributed, there is considerable uncertainty about the actions of independent team members. It is quite possible that the independent pursuit of local objectives implicitly results in team members taking on adversarial roles as competitors for limited resources or tasks. Components of this research include risk sensitive optimization and risk management techniques such as Conditional Value at Risk, applied to situations where enemy forces are attempting to deceive or destroy friendly forces. Other research components include the development of distributed algorithms for policy generation, with real-time policy updates based on observation or prediction of the behavior of teammates or adversaries.

SF.45.05.B4001: Modeling Complexity in Ignition of Energetic Materials

S. Johnson

850-882-8979

Over the past 150 years, there have been countless studies of the reactive behavior of energetic materials. However, there is not yet a deep, quantitative understanding to predict the ignition threshold from mechanical and/or thermal stimuli in terms of basic physical and chemical properties. Current understanding of ignition sensitivity is still empirical and qualitative. Another example is the effect of additives (reactive or inert) on reactive behavior. The difficulty in achieving such a fundamental understanding is attributed to the fact that underlying physical processes are controlled by heterogeneous mechanisms, which are often localized and cannot be adequately described by average parameters such as pressure, density, and temperature. Global behavior represented by these thermodynamic variables does not, by definition, describe the subscale physics that involve strongly coupled, transient, thermal, physical, and chemical processes, and microstructure evolution. The one complicating factor that is often ignored is that explosives are a stochastic medium.

Various efforts combine both computational modeling and new diagnostic techniques that can probe fast material behavior at the crystal or grain level. Computational effort involves direct simulations of mesoscale response behavior using continuum codes and representative microstructures at the grain level. However, results are exceedingly complex and require careful data analysis to extract physical understanding. Plus, they are known to be dependent on models and materials properties used for the simulation. Therefore, the impact of direct mesoscale simulation has been limited to understanding qualitative behavior of hot-spot formation (energy localization) and its distribution, and what is needed to gain reliable qantitative results.

We are interested in an alternative approach to modeling the ignition of energetic materials, in which hot spots are described by a statistical distribution. Such a distribution depends on the details of the materials at the grain scale and loading. However, the evolution of the distribution may be modeled by mean field variables (concept of enslaving) and microstructure related parameters. In addition, the distribution can be viewed as a path from hot spots to "burn" over a bridge of chemistry at the appropriate condition of temperature. Thus, the distribution is seen as synonymous to the distribution of reactive interface across which mass transform from solid to gas. In this view, the interface will acquire a fractal-like feature. The challenge is to develop a conceptual framework and a working model that are simple, but complex enough to capture the essential microscale physics that occur in stochastic media.

SF.45.08.B2564: Vision-Based Guidance and Control

Curtis, J.W.

(850) 883-2564

Research opportunities are available to explore the intersection of computer vision with the guidance and control of unmanned aerial vehicles and munitions. Vision-based sensors are typically small, lightweight, and inexpensive; these qualities make them well suited for deployment on next-generation unmanned vehicles and weapons. There is a gap in the literature regarding the use of vision-only sensing for terminal guidance and many fruitful lines of research could be opened in order to investigate the limitations and advantages offered by monocular or multicamera sensor platforms. Work is currently in progress that explores the use of visual information to successfully estimate position and attitude; this navigation-specific work might dove-tail nicely with an investigation of vision-based guidance law design. Furthermore, since a visual sensor can be used for both ego-estimation and target relative position and motion, a possibility exists to develop an integrated guidance and control system based primarily on information derived from one or more cameras.

SF.45.08.B6110: The Science and Technology of High Velocity Impact

R. Abrahams

850-882-7978

We have a gunnery range that allows projective launches over the range of meters per second to 8 km/s using smooth bore compressed gas gun, oblique impact gun, and powder guns, explosively formed projectiles, or shaped charge jets. Use of these high speed projectiles with targets can result in high pressures in the media. The smooth bore guns provide precision controlled impact conditions to determine the high pressure equation-of-state, constitutive behavior, and failure of a wide variety of materials. These are complemented with time resolved (nanosecond resolution) interferometry referred to as VISARs, and PDV gauges. Current applications include determining the target response for a variety of materials including but not limited to metals, bulk and nano-energetics, reactive materials, liquid crystals, and porous geologic media. In addition, opportunities exist to further the current technologies to probe heterogeneous materials such as energetics and porous media at a microstructural level experimentally, theoretically, and computationally. Other topics include determination of fracture and fragmentation properties of solids and liquids.

SF.45.13.B0830: Trusted and Flexible Autonomous Systems

Murphey, R.A.

(850) 882-2962

Autonomous weapons are ground, air, or sea launched kinetic munitions that utilize on-board and networked information to better understand an uncertain, adversarial battlespace and make decisions to maximize engagement goals. This area of study is focused on increasing flexibility and adaptability of weapons to meet operator intent even in environments & situations they were not designed for. There are 4 primary areas of interest for study: 1. Components & systems that are inherently reconfigurable are necessary to build autonomous systems with greater flexibility and therefore an ability to achieve the mission despite unforeseen impediments. AFRL/RW has conducted a number of studies that indicate that bio-inspired wide field-of-view sensing and proliferated sensing – processing – actuation – morphing/adaptation inherently provide more potential for flexibility in autonomous behaviors. 2. Awareness, structure, and reasoning that allow inference of high level tactics from proliferated sensing or naturally create robust hedges to extreme outcomes will provide greater flexibility in autonomy. Ultimately methods of inference and robustness can result from either a deliberate or minimalist approach but the focus is always on the “correctness” of understanding, decisions and outcomes. 3. A mathematical control language for autonomy, that defines trust admissible regions/ patterns/groupings for autonomous decisions, would enable rapid & robust reconfiguration of a system. Results in theorem proving, language parsing, computing theory and complexity, & quantitative local analysis indicate that a constructive framework for flexible autonomy is possible. 4. “Cognitive matching” – whereupon a machine anticipates the human's decisions & actions while the human gains insight into the machine decision process - can build trust with operators using autonomous weapons. Cognitive matching experiments in AFRL have shown that machines that measure operator work-load can tailor information content and forestall operator decision failures.

Keywords: Trusted autonomy, reasoning systems, robust decision making, super quantiles, computing theory; human supervised autonomy.

SF.45.13.B0832: Bioinspired Principles for Autonomous Munitions Systems

Dickinson, B.T.

(850) 883-2645

Insects utilize a wide range of sensing modalities to achieve robust and agile flight. These modalities are often occur in arrays composed of noisy mechanosensors in numbers of hundreds, thousands, or more; and are distributed over organs or locations of the body according to their function. In contrast, modern guidance, navigation and control designs rely on feedback from local and precise instrumentation such as inertial measurement units, gyroscopes, global positioning systems and pitot tubes. We aim to derive scalable principles from the existing knowledge base surrounding the information processing and sensing modalities of natural flyers to develop fundamental and scalable control methodologies that increase robustness and minimize the human interaction necessary for effective engagement of munitions platforms. This may include, but is not limited to, biologically inspired and derived methodologies for the feedback of munitions attitude, atmospheric turbulence, and wind shear or gusts.

SF.45.13.B1126: Fundamental Research of Novel Energetic Materials

C.M. Lindsay

850-882-1543

Tom Krawietz

850-882-9769

Chad Rumchik

850-882-7243

The goal of our team is to discover, develop, integrate and transition energetic materials technology that maximizes lethality, survivability and safety for air-delivered munitions. We study the basic processes and scientific phenomena that are necessary to predict, design and characterize energetic materials. A variety of topics are being considered for enhancing the energy density of materials based upon improved reaction rates while maintain stability under ambient storage conditions (ie. Room temperature, humidity). Specific topics of interest include: 1) energetic films via spin casting of fuel-oxidizer blends, 2) light tunable sensitization of energetic materials, 3) self-assembly of thermite-based structural materials, 4) scale up processes such as resonant acoustic mixing and 5) synthesis of energetic nanoparticles using superfluid helium droplet assembly and other techniques. A successful candidate will possess a strong multidisciplinary experimental background in physics, chemistry and materials science/engineering with knowledge of modeling and simulation techniques.

 

References:

1. Prakash, A., A.V. McCormick, and M.R. Zachariah, Tuning the Reactivity of Energetic Nanoparticles by Creation of a Core−Shell Nanostructure. Nano Letters, 2005. 5(7): p. 1357-1360.

2. Ferrando, R.; Jellinek, J; and Johnston, R.L. Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles. Chem. Rev., 2008, 108 (3), pp 845–910.

3. Heting Li, Mohammed J. Meziani, Fushen Lu, Christopher E. Bunker, Elena A. Guliants and Ya-Ping Sun Templated Synthesis of Aluminum Nanoparticles - A New Route to Stable Energetic Materials. J. Phys. Chem. C, 2009, 113 (48), pp 20539–20542

4. Lei Zhou, Ashish Rai, Nicholas Piekiel, Xiaofei Ma and Michael R. Zachariah

Ion-Mobility Spectrometry of Nickel Nanoparticle Oxidation Kinetics: Application to Energetic Materials. J. Phys. Chem. C, 2008, 112 (42), pp 16209–16218.

5. Rusty W. Conner and Dana D. Dlott. Time-Resolved Spectroscopy of Initiation and Ignition of Flash-Heated Nanoparticle Energetic Materials. J. Phys. Chem. C, 2012, 116 (28), pp 14737–14747.

6. Yong Qin, Yang Yang, Roland Scholz, Eckhard Pippel, Xiaoli Lu, and Mato Knez. Unexpected Oxidation Behavior of Cu Nanoparticles Embedded in Porous Alumina Films Produced by Molecular Layer Deposition. Nano Lett., 2011, 11 (6), pp 2503–2509.

7. William K. Lewis, Barbara A. Harruff, Joseph R. Gord, Andrew T. Rosenberger, Thomas M. Sexton, Elena A. Guliants, and Christopher E. Bunker. Chemical Dynamics of Aluminum Nanoparticles in Ammonium Nitrate and Ammonium Perchlorate Matrices: Enhanced Reactivity of Organically Capped Aluminum. J. Phys. Chem. C, 2011, 115 (1), pp 70–77

Keywords: Energetics, Thermites, Nanoparticles, Energy density, Reactivity

SF.45.16.B0001: Additive Manufacturing of Multifunctional Materials

Schrand, A.

850-882-1538

The goal of our team is to develop, demonstrate, and implement additive manufacturing (AM) technologies to rapidly design, prototype, and manufacture critical munitions components such as survivable fuze electronics, reactive structures and energetic materials for modular, flexible weapons. Specific topics of interest include: 1) Increasing lethality of miniaturized weapons, 2) Development of fuze components for small form factor/miniature warhead concepts, 3) Use of alternative processing techniques for explosives and energetic materials, 4) Development of additive manufacturing processes for lightweight, cellular warhead cases and embedded fuze housings and 5) Creation of reactive structural materials that offer strength and also energy on demand. A successful candidate will possess a multidisciplinary experimental background in Materials Science/Engineering, Electrical Engineering, Physics, Chemistry and other relevant Science & Engineering fields with a strong publication record. Candidates with experience in AM design and demonstration preferred.

SF.45.17.B0001: High-Rate Dynamics and Experimental Methods

Dodson, Jacob

850-883-1920

Research will involve designing and performing analytical and experimental studies of the time- and frequency-domain response of both simple and complex mechanical systems to high-amplitude, short duration impulsive loads. We are also interested in structural dynamics experimentation, analysis, and/or simulation. Opportunities exist to perform research in the following technical areas:

(1) Microsecond Health Monitoring & Prognosis: cyber-physical estimation, prediction and reaction using the high-rate dynamics of a structure to detect and mitigate damage, and perform prognosis on the remaining usable life. These methods should be able to be implemented on a microsecond time scale.

(2) Novel High Rate Dynamics Experimentation & Instrumentation: development of novel experimental testing methods and instrumentation for evaluating the survivability and response of materials, sensors, electronics, and mechanical interfaces under high-rate dynamic loading;

(3) Harsh Environmental Characterization: development of methods and metrics to characterize the bulk and internal thermo-mechanical environment of a complex mechanical system under impulsive loading;

SF.45.17.B0002: Characterization of Photonic Crystals

Touma, Jimmy

850-883-0876

The last two decades have seen a tremendous interest in “controlling light” using photonic crystals. Photonic crystals, also known as photonic band-gap materials, are periodic structures that forbid light of a certain frequency range from propagating in the material. Photonic crystals occur naturally in beetle and butterfly wings and on the feathers of certain birds. They are also attributed to the active color change in chameleons. By studying the properties of photonic crystals, researchers can gain insight in how insects interpret reflected light signals from other insects to distinguish between conspecifics and insects of other species, and to recognize gender in conspecifics.

We would like to develop methodologies to analyze the band structure of photonic crystal lattices of design interest to:

  • compute the reflection and transmission spectra for finite photonic crystal arrays with due attention being paid to frequency bands and incidence angles of interest;
  • develop a complete numerical models for select crystal designs;
  • Validate our designs and hypotheses by analyzing data produced by the experiments conducted within this project.

Research is not limited to PC but can also include metamaterials & metasurfaces.

Applicants must be US citizens with a Ph.D. from an accredited university.

Keywords: photonic crystals; optical band-gaps; metamaterials; plasmonics; metasurfaces; butterfly wing scales; iridescence; Brillouin zone.

AFRL/Munitions

Dr. Crystal Pasiliao
AFRL/RW
101 West Eglin Boulevard
Eglin Air Force Base, Florida 32542-6810
Telephone: (850) 882-8809
E-mail: crystal.pasiliao@us.af.mil