Seminar Archive 2011 - 2015

The purpose of this Office of Naval Research originally sponsored Future Naval Capabilities UAV project is to demonstrate the feasibility to automatically signal the initiation of UAV descent. The current NAVAIR objective is to recover the UAV on-board a moving vessel within reasonable safety margins regardless of the seaway. The Energy Index, the operative component of the Landing Period Designator, identifies quiescent periods to initiate aircraft descent based on aircraft deck limit definitions. Dynamic Interface simulation provides the physical information from which initial deck limits might be derived. Energy Index quiescent indications for UAV recovery opportunities are presented outside of current operating limits. A brief synopsis of the theory and calculation of the ship motion simulation and Energy Index programs, are discussed. Undercarriage deflection to encountered deck forces and aircraft stability, were calculated. Using Launch and Recovery “rondelles” (or speed-polars), the deck limits at specific ship’s speeds may be identified. Impacts on the proposed deck limits, are discussed. Percent improvement of operational availability is demonstrated. The results using simulated data are compared to those recorded during dynamic interface testing at sea showing strong correlation between computational approaches.

• Ms. Judy Bergmann
• MIRATEK, Inc.
• 321 McBryde Hall
• 2:00 p.m.
• Faculty Host: Dr. Joseph Schetz

Feb. 26, 2013 – The presentation will be in two parts. The first part will provide a brief overview of wind tunnel basics and look at a selection of wind tunnel test types at AEDC (Arnold Engineering Development Complex), mostly performed in 16T, the 16-foot transonic wind tunnel. Some of the tests discussed date back to the early years of 16T, but most were more recent. The second part of the presentation highlights some of the current projects in hypersonics being overseen by Test and Evaluation/Science and Technology (T&E S&T), High-Speed Systems Test (HSST) of the DoD Test Resources Management Center (TRMC).

Wind tunnel testing dates back to the late 1800s. A basic wind tunnel was designed and used extensively by the Wright brothers in the first decade of the 1900s to refine the shape of the airfoil used on the first powered aircraft. The wind tunnels at AEDC provide some of the best flow quality and highest productivity of any in the world. Many types of tests are performed in the wind tunnels at AEDC, some considered typical, others less common. Basic wind tunnel operation is described along with several of the types of tests performed at AEDC.

The hypersonic flight regime has been studied and tested for more than 60 years. Developments in the past several years have advanced the state of the art significantly. T&E S&T is tasked with providing technical oversight of programs that devise methodologies for ground testing hypersonic flight regime technologies. Several of the projects that have been completed recently or are still in progress are described.

• Dr. Carolyn Beck
• University of Illinois at Urbana-Champaign
• 104D Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Mazen Farhood

Feb. 25, 2013 – In this talk we present a computational framework for solving a large class of dynamic clustering and coverage control problems, ranging from those that arise in deployment of mobile sensor networks to identification of ensemble spike trains in neuronal data. This framework provides the ability to identify natural clusters in an underlying dynamic data set, and allows us to address inherent trade-offs such as those between cluster resolution and computational cost. More specifically, we define the problem of minimizing an instantaneous coverage metric as an optimization problem using a Maximum Entropy Principle formulation, constructed specifically for the dynamic setting. Locating cluster centers and tracking their associated dynamics is cast as a control design problem that ensures the algorithm achieves progressively better coverage with time.

• Dr. Robert Lucht
• Purdue University
• 104D Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Lin Ma

Feb. 18, 2013 – Over the last several years we have developed high-pressure combustion test rigs with optical access with funding from private industry, NASA, and DOE. Both aviation gas turbine and power-generating gas turbine test rigs are presently operational. The design of the window assemblies for the high-pressure, high-temperature conditions encountered is described, along with lessons learned from our early design efforts. The operation of the facility and the integration of remotely operated laser diagnostic systems with the combustion test rigs are discussed in detail.

Recent measurements in these combustion facilities are discussed. The laser diagnostic methods that we have used to investigate high-pressure combusting flow fields include coherent anti-Stokes Raman scattering (CARS) and 5 kHz OH planar laser-induced fluorescence (PLIF) imaging. These methods were used recently to investigate the injection of natural gas/air jet into a subsonic vitiated crossflow at a pressure of 6 bar. Dual-pump H₂/N₂ CARS was used to measure the temperature field and the H₂ CARS signal was used to indicate regions of high chemical reactivity. The same reacting flow field was also investigated using 5 kHz OH PLIF, and 5 kHz PIV measurements will be performed in the near future. Our recent work on the application of ultrafast laser systems for 5 kHz single-laser-shot CARS measurements will also be discussed.

• Dr. Owen Brown
• Kinsey Technical Services
• 104D Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Troy Henderson

Feb. 11, 2013 – This seminar will provide an overview of DARPA's System F6 program and discuss the challenges and benefits of fractionated spacecraft architectures. System F6 is focused on development of technologies that will enable the fractionation of space systems. Fractionation is the networking of disaggregated satellites and ground nodes, wherein various software and hardware resources can be shared across the network. Cluster flight of space modules is a focus of the System F6 program - the navigation approach, as well as the novel software implementation of it, will be discussed.

• Dr. Li Qiao
• Purdue University
• 104D Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Lin Ma

Feb. 4, 2013 – Nanofluid fuels are liquid fuels with a stable suspension of nanometer-sized particles (e.g., energetic nanomaterials and nanocatalysts). Depending on the physical and chemical properties of the added nanomaterials, nanofluid fuels can achieve better performance, such as increased energy density, faster burning rate, easier and faster ignition, and enhanced catalytic effects. They can potentially be used for future hypersonic propulsion systems, which largely depend on the ability to use liquid fuels of high energy density, short ignition delay, and high reaction rate. Nanofluid fuels may also be used for power/thrust generation under special circumstances. For example, they can provide higher power or thrust for a longer time for compact systems where the volume of carried fuel is limited, such as an unmanned aerial vehicle (UAV) or a power MEMS. Furthermore, the nanofluid fuels containing various nanostructured ignition agents may allow for the distributed ignition of fuels using light sources, which could greatly improve combustion efficiencies, as opposed to conventional single-point ignition. Lastly, nanofluid fuels exhibit significantly enhanced mass and heat transport properties resulting from the random Brownian motion and the thermal radiation properties of nanoparticles, which could aid in combustion. This seminar will present our recent results on the research of tailored high-performance fuels using nanoscale energetic materials as additives. The effects of several parameters on fuel’s colloidal stability and combustion performance will be discussed, including particle material, loading rate, particle size, as well as the type of base fluid and the use of a surfactant. These understanding will provide important guidelines for the optimized use of nanomaterials in terms of material, surface functionalization, particle size, and concentration in liquid fuels to achieve the desired performance.

• Dr. Stephen Clay
• Wright Patterson Air Force Base
• 1050 Torgersen Hall
• 2:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Jan. 30, 2013 – Composite structures offer many advantages over conventional metallic structures, including higher specific strength and stiffness. These benefits should translate into lighter weight structures, but this is not always the case. For laminated polymer matrix composites, the matrix dominated out-of-plane properties and bearing strength are very low. To compensate, extra material and heavy mechanical fasteners are often applied to structural joints. Dr. Clay will discuss several of the emerging joining technologies being developed by the Air Force Research Lab and their industrial and university partners in order to overcome these shortcomings. Some of the techniques to be discussed include z-pinning, stitching, flocking, co-melding, and 3-D woven Pi preforms. An overview of the Air Force Research Lab will also be presented.

• Dr. Karen M. B. Taminger
• NASA Langley Research Center
• 104D Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Jan. 28, 2013 – This lecture is intended to introduce the world of materials engineering and how this knowledge helps us manufacture airplanes, spacecraft and other useful objects. It will focus on an additive manufacturing process called “Electron Beam Freeform Fabrication (EBF³)”. We have been developing this process for ten years at NASA Langley, and it provides a good example of how an idea can be brought to reality and even demonstrated in zero gravity. The EBF³ process uses a focused electron beam in a vacuum environment to create a molten pool on a metallic substrate; then translated while metal wire is fed into the pool. A part is thus built directly from a CAD drawing in a layer-additive fashion. Because this is a layer-additive process, metal can be placed only where it is needed and the material chemistry and properties can be tailored throughout a single-piece structure. This allows new design methodologies such as integrated sensors, tailored structures, and complex, curvilinear stiffeners to be designed to support loads and perform other functions such as aeroelastic tailoring or acoustic dampening. All of this is made possible with modeling and simulation. This seminar will follow the maturation of the EBF³ technology from inception to commercialization and will describe how a manufacturing process can influence future aircraft designs by providing a solution that enables multidisciplinary optimization.

• Dr. Matthew Orr
• Configuration Design
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Joseph Schetz

Dec. 10, 2012 – This presentation will provide an overview of Boeing’s Commercial Airplanes (BCA) product development organization commercial airplane market forecast, and airplane development work. It will then cover what Configuration Design and Engineering Analysis (C&EA) group does at Boeing and discuss the key attributes of an airplane designer.

• Dr. Lesley Weitz
• The MITRE Corporation
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Craig Woolsey

Dec. 3, 2012 – The FAA is in the midst of NextGen, which is a major overhaul of the nation’s air traffic system. A key part of NextGen is the deployment of Automatic Dependent Surveillance – Broadcast (ADS-B), which is a surveillance technology that relies on a satellite-based navigation source and a datalink to broadcast an aircraft’s state information. That information will be used by air traffic control on the ground and may be used by ADS-B-IN-equipped aircraft in the surrounding airspace. Avionics applications that take advantage of this increased information on the flight deck are currently being developed through avionics standards activities in the US and Europe.

Interval Management (IM) is just one of a number of efficiency- and safety-enhancing applications that are enabled by ADS-B. IM is a near-term operational concept that will provide more precise spacing between aircraft pairs. In an IM operation, the air traffic controller will instruct an “IM aircraft” to achieve and maintain a desired spacing interval relative to a “target aircraft”. The IM aircraft is equipped with avionics that provide the flight crew with speed commands to achieve and maintain the specified spacing interval relative to the other aircraft. IM operations are envisioned in a variety of environments where more precise spacing between aircraft will help the air traffic controller to meet operational goals (e.g., higher throughput at busy airports). IM is also expected to increase the opportunity for aircraft to fly more fuel-efficient trajectories.

This presentation will describe the IM application and some of the technical challenges that are being addressed in the ongoing development of avionics standards and ground automation to support Air Traffic Controllers.

• Col. David Anhalt
• Space Systems/Loral
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Troy Henderson

Nov. 26, 2012 – Hosted payloads are government mission capabilities that are integrated on commercial communication satellites. A government hosted payload performs specific government missions using resources provided by the commercial host platform.

Mr. Anhalt will speak about the role commercial satellites can play in hosting science payloads for NASA and military payloads for the Department of Defense. Concepts for commercially hosted payloads are part of a broader trend by government to increasingly rely on the commercial space sector for more of their goods and services. Federal budget pressures are forcing both the civil and national security sector to consider the economic advantages of leveraging the vibrant, productive commercial space sector.

The Space Age has spawned three distinct sectors of space activities: civil, national security, and commercial. While each sector trains their young professionals at the same engineering and business schools and often rotates talent in mid-career, the three sectors have nevertheless developed distinctly different cultures, business approaches, and preferences for solving their core problems.

Architecture has been defined as “the structure – in terms of components, connections, and constraints – of a product, process, or element.” (Dr. Eberhardt Rechtin, and Mark W. Maier, The Art of Systems Architecting.) By using the lens of systems architecture the speaker will identify underlying technical, programmatic and policy issues that impact the commercial hosting enterprise.

Additionally, the speaker will be available to answer question about the roles engineers play at satellite manufacturing companies like Space Systems/Loral in mission design, spacecraft development, manufacturing, test, operations and business development.

• Dr. Noel Clemens
• The University of Texas at Austin
• Location: 112 Robeson Hall
• Time: 4:00 p.m.
• Faculty Host: Dr. Lin Ma

Nov. 12, 2012 – Ablation remains a topic of current interest in the aerospace community owing to the need to develop thermal protection systems for spacecraft that undergo entry into planetary atmospheres. Ablation is a complex multi-physics process that involves high-temperature thermochemistry, radiation, gas-surface interactions, turbulent transport, mechanical erosion, etc., all of which combine to make it quite a challenging process to study. A particularly important physical process that remains very difficult to model is the transport of ablation products in high-speed turbulent boundary layers that develop in the presence of surface roughness and strong pressure-gradients. The study of scalar transport is enabled by a new technique that has been developed at The University of Texas at Austin, which uses planar laser-induced fluorescence of the gas-phase products resulting from a sublimating ablator (naphthalene) exposed to a high-speed flow. In this presentation details of the technique will be discussed including measurements of the photo-physical properties of naphthalene such as the temperature variation of the absorption and quenching cross-sections. Such data are necessary to enable the use of the technique for quantitative measurements of the scalar concentration. Results will be shown for the application of the technique to study scalar dispersion in a Mach 5 boundary layer and to visualize ablation on a subscale space capsule model.

• Dr. Jack Langelaan
• The Pennsylvania State University
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Craig Woolsey

Nov. 12, 2012 – In October 2011 Team Pipistrel-USA.comʼs electric powered Taurus G4 won the Green Flight Challenge, flying nearly 200 miles at an average ground speed of 107 miles per hour and an equivalent fuel efficiency of 403.5 passenger miles per gallon. This was the first demonstration of a practical general aviation mission (combining payload, speed, range, and endurance typical of GA) by an electric powered aircraft, and the achieved fuel efficiency is roughly six times better than that of typical general aviation aircraft (and twice that of a Toyota Prius).

This talk will discuss design of the G4, give an overview of its electric power system and describe the flight planning algorithms that were used during the competition.

• Dr. Ella Atkins
• University of Michigan
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Craig Woolsey

Nov. 5, 2012 – Aircraft and spacecraft are now able to plan and autonomously execute task-level actions as well as optimizing and precisely following 4-dimensional trajectories. Automation has, however, struggled to effectively manage off-nominal situations, a particularly important capability when such events introduce increased risk of losing a costly vehicle or of causing harm to people or property. This presentation will describe Dr. Atkins’ long-term research in improving safety and robustness through autonomous contingency management with application to aircraft and spacecraft.

Spacecraft operate in a harsh environment, are costly to launch, and experience unavoidable communication delay and bandwidth constraints. The objective of the presented work is to optimize science goal achievement while identifying and managing encountered faults. The relative value of science data collection is traded with risk of failure to determine an optimal policy for mission execution. Our major innovation is to incorporate fault information based on the dynamics of the spacecraft and on the internal composition of the spacecraft. Approximate dynamic programming (ADP) is applied to address computational complexity challenges.

Dr. Atkins will also describe her long-term research in emergency flight management aimed at safely recovering and landing a disabled aircraft. Her research has focused on envelope-adaptive flight planning and guidance, with a more recent project focusing on flight safety assessment. Results from her research will improve safety in manned and unmanned aircraft, and are beginning to inform risk analysis and mitigation processes relevant for certification of small unmanned aircraft systems (UAS).

• Dr. Scott Slocum
• ExxonMobil Upstream Research Company
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Oct. 29, 2012 – Model tests of two different types and two different scales were performed with test cylinders fitted with a freely-rotating riser fairing. At lower flow speeds, both tests showed the fairings to be effective in suppressing vortex-induced vibration (VIV) of the cylinder and in reducing drag. In both tests, however, large lateral cylinder oscillations developed once the flow exceeded a certain critical speed. Motion amplitudes in one test significantly exceeded those of a bare pipe undergoing VIV. A simple two-dimensional model of aircraft wing flutter was used to better understand the cause of the oscillations and to relate the onset of the motion to the fairing's specific design characteristics. The model predicted the observed threshold speeds with reasonable accuracy, suggesting that riser designers can borrow from existing aerodynamic flutter theory to ensure that riser fairings are designed to remain dynamically stable over the range of current speeds expected in service.

• Dr. James Brasseur
• The Pennsylvania State University
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Eric Paterson

Oct. 22, 2012 – The design and control of future generations of advanced commercial wind turbines will benefit from detailed quantifications of the interactions between the turbulence within the lower atmospheric boundary layer and the large variations in stresses on the blade surfaces in time and along blade span. In particular, the more energetic turbulent motions in the atmospheric surface layer, the region dominated by commercial wind turbines, are of order the rotor disk in scale and vary in structure depending on atmospheric stability and surface topography. As these energetic atmospheric eddies sweep through the rotor disk, they change the magnitude and the angle-of-attack of the incoming velocity vector relative to the rotating blades, leading to rapid changes in blade surface boundary layer structure, large variability in surface stresses and, consequently, large temporal fluctuations in blade and shaft bending moments, shaft torque and turbine power. Consequences include reduced reliability through premature blade, bearing and gearbox failure, and suboptimal control strategies. I shall describe a DOE-funded program to develop the Penn State "Cyber Wind Facility," a unique ‘experimental’ capability using petascale computer resources and the latest technologies in high-performance computing to collect ‘data’ for advanced wind turbine research, analysis and design. By integrating high-fidelity large-eddy simulation of the atmospheric boundary layer with high-resolution hybrid URANS-LES, and by including blade elasticity, tower deformation, and platform-wave interactions in offshore configurations, the Cyber Wind Facility is conceptualized akin to a full-scale wind turbine field facility designed to generate the highest fidelity most well-resolved 4-D data possible simultaneously over the entire wind turbine domain, for both onshore and offshore wind turbines. Planned extensions include turbine-turbine interactions and the improvement of actuator line methods for wind farm simulation.

• Dr. Dennis McLaughlin
• The Pennsylvania State University
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. K. Todd Lowe

Oct. 15, 2012 – Penn State research addresses the need for jet noise reduction for modern military aircraft. The noise induced hearing loss suffered by Navy personnel working in close proximity to tactical aircraft, particularly for carrier-based operations, is of increasing concern to the US Navy. However, acoustic measurements for such exhaust jets are scarce, due to the cost involved in making full scale measurements and the lack of details about the exact geometry of the nozzles. Past efforts at Penn State University, in partnership with the NASA Glenn Research Center and GE Aviation, was focused on developing methodology for using data obtained from small and moderate scale experiments to reliably predict the most important components of full scale engine noise. The experimental results demonstrated good agreement between small scale and moderate scale jet acoustic data, as well as between heated jets and heat-simulated ones.

Our most recent efforts have developed a methodology and device for the reduction of supersonic jet noise. The goal is to develop a practical active noise reduction technique for low bypass ratio turbofan engines. The method involves precise blowing into the divergent section of the engine exhaust nozzle to produce fluidic inserts that mimic “hard walled” corrugated inserts. By altering the configuration and operating conditions of the fluidic inserts, active noise reduction for both mixing and shock noise has been obtained. Substantial noise reductions have been achieved for mixing noise in the maximum noise emission direction and in the forward arc for broadband shock-associated noise. To achieve these reductions (on the order of 5 and 2 dB for the two main components respectively) practically achievable levels of injection mass flow rates have been used. The total injected mass flow rates were less than 4 % of the core mass flow rate and the effective operating injection pressure ratio was maintained at or below the same level as the nozzle pressure ratio of the core flow. Refinement and optimization of this technique is being pursued at Penn State University.

• Dr. P. D. Weidman
• University of Colorado
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Cornel Sultan

Oct. 8, 2012 – Equations modeling the shape of the Eiffel Tower are investigated. One model, based on equilibrium of moments, gives the wrong tower curvature. A second model, based on constancy of vertical axial stress, does provide a fair approximation to the tower's skyline profile of twenty-nine contiguous panels. However, neither model can be traced back to Eiffel's writings. Reported here is a new model embodying Eiffel's concern for wind loads on the tower, as documented in his communication to the French Civil Engineering Society on March 30, 1885. The result is a nonlinear, integro-differential equation which may be solved to yield an exponential profile. An analysis of actual panel coordinates reveals a profile closely approximated by two piecewise continuous exponentials with different growth rates. This is explained by specific safety factors for wind loading that Eiffel & Company incorporated in the design and construction of the free-standing tower.

• Dr. Bjoern Kiefer
• Technical University Dortmund
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Gary Seidel

Sept. 24, 2012 – Active and multifunctional materials have drawn considerable interest in recent years, as they show great potential for enabling novel sensing, actuation, transduction, energy harvesting and bio-mimetic applications, to be employed, for example, in aerospace, the automotive industry, microelectronics and the biomedical field. In addition to the exploration, synthesis and characterization of new material systems, the accurate modeling and simulation of their constitutive response is of key importance in the endeavor of leading the application development process beyond purely conceptual ideas.

We focus here on the modeling of a subclass of such materials exhibiting magneto-mechanical coupling, namely giant magnetostrictives, magnetic shape memory alloys and magneto-active polymers. From a modeling standpoint, great challenges stem from the complex coupled, nonlinear and inelastic nature of the material response. This macroscopic behavior is often driven by microstructural changes, such as phase transformations or twin-boundary and magnetic domain wall motion. On the other hand, strongly-coupled nonlinear boundary value problems must be solved for device analysis.

Three particular modeling cases are discussed and illustrated with numerical examples. First, as an extension of classical approaches of computational inelasticity, a return-mapping-based algorithm for magnetic shape memory behavior is presented. Secondly, a new and rather general variational-based modeling approach and computational implementation of macroscopic continuum magneto-mechanics is presented with a special focus on dissipative magnetostriction. Finally, a brief overview is given on recent research activities related to computational magnetomechanics in the geometrically-nonlinear setting with an application to magnetoactive polymers.

References

[1] B. Kiefer and D. C. Lagoudas, Modeling the Coupled Strain and Magnetization Response of Magnetic Shape Memory Alloys under Magnetomechanical Loading, Journal of Intelligent Material Systems and Structures Vol. 20, 143–170, 2009.

[2] C. Miehe, B. Kiefer and D. Rosato, An Incremental Variational Formulation of Dissipative Magnetostriction at the Macroscopic Continuum Level, International Journal of Solids and Structures Vol. 48, 1846–1866, 2011.

[3] B. Kiefer, T. Bartel and A. Menzel, Implementation of Numerical Integration Schemes for the Simulation of Magnetic SMA Constitutive Response, Smart Material and Structures Vol. 21, doi:10.1088/0964-1726/21/9/094007, 2012.

• Dr. Owen Hughes
• Virginia Polytechnic Institute and State University
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Sept. 17, 2012 – On Friday January 6, 2012 the speaker disembarked in Civitavecchia from a seven-day cruise on the Costa Concordia. Exactly one week later, on the night of January 13, the ship departed from Civitavecchia toward its first port of call, Savona. Two hours later, off the island of Giglio, it struck a submerged rock which tore an underwater gash 50 meters (161 feet) long on the port side, flooding several compartments including the engine room. The ship immediately lost all main engine power. A few minutes later it lost electricity and lights, but emergency generators restored both. At first the ship moved away from the land with a heel to port and gradually came to a stop. The ship was probably in a condition of “loll” because when the bow thrusters were used to turn the ship around, the 23 mile-per-hour onshore wind rolled the ship to a starboard heel and slowly pushed it toward the land. It finally grounded about an hour after the collision, only a few hundred meters from the port of Giglio. Eight minutes after grounding, the captain ordered abandon ship. Amid much confusion most of the 26 lifeboats were launched in about 30 minutes, but after this the increasing heel to starboard prevented any further launchings. Forty five minutes after grounding the ship capsized to starboard and the approximately 100 remaining passengers clung to the high side of the ship. The next morning they were removed by helicopter.

The seminar will give details about the accident and explain what is a “condition of loll”, which is why the ship heeled and capsized to starboard, even though the gash in the hull was on the port side.

The second part of the seminar will explain how the wreck is to be removed. It will be the largest righting and refloating operation in history, and will take about one year. The ship will then be towed to a shipyard and broken up. The ship cost about $600 million in 2004 dollars, and the removal of the wreck will cost about $300 million.

• Dr. Robert Meakin
• CREATE-AV
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Eric Paterson

Sept. 10, 2012 – The spectrum of engineering processes that span the design, development, deployment, and sustainment of air vehicles is vast and can usefully be referred to collectively as “aircraft acquisition”. The potential for multi-disciplinary, physics-based simulation modeling and High Performance Computing (HPC) to positively impact the engineering processes associated with aircraft acquisition is large. The argument put forward in this work is not the pitting of the traditional ground-based and flight test paradigm for generating needed engineering data against the capacity of physics-based simulation. Rather, it is to assert that multi-disciplinary, physics-based simulation and HPC, in combination with traditional means of generating engineering data, represent an opportunity to fundamentally change the paradigm for aircraft acquisition. The addition of physics-based simulation as a means to generate actionable engineering data enables increased capacity of the engineering workforce, reduced workloads through streamlined and more efficient workflows, and minimization of the need for rework due to an ability for early detection of design faults and aircraft performance anomalies.

Regardless of the source, in order for engineering data to be actionable, the data must be available when it is needed, correctly represent the governing physics, and be of quantifiable quality. While the preceding may appear to be a statement of the obvious, it implies a number of fundamental principles, the realization of which is nontrivial. Timeliness, physical accuracy, and uncertainty quantification are general headings. Each of these is essential to making effective programmatic decisions, but if one had to choose the most important, perhaps it would be timeliness. When the time comes to make a decision, the fact that “exact data might be available next week” is irrelevant. The decision is being made now. For example, a countdown in the launch of a spacecraft generally includes scheduled pauses to accommodate go/no go decision points. If system readiness data is not available at the scheduled time, the decision
maker will make a decision anyway – launch or delay. Launch if the decision maker deems the risk associated with the missing data to be small, or delay to await analysis and possibly the next launch window. A lack of timeliness associated with engineering data always has the effect of increasing risk and causing programmatic delays.

Decisions associated with aircraft acquisition, span engineering processes beginning with conceptual design and continuing through all subsequent phases of development, deployment, and sustainment of the final fleet of aircraft fielded. Paradoxically, decisions made at the earliest phases of acquisition are the most significant, setting overall development and life-cycle costs, yet they are currently supported by the lowest fidelity engineering data and highest uncertainties. The conundrum is compounded by the fact that design cycle-time trends inversely with position across the aircraft acquisition spectrum – meaning that not only do early-phase engineering decisions have long-term impacts, but the time available to generate needed engineering data to support the decisions is minimum. Herein lies the opportunity for physicsbased simulation and HPC to enable a paradigm change. Multi-disciplinary, physics-based simulation and HPC represent a capacity, through virtual testing, to generate needed engineering data at required levels of physical accuracy. Accordingly, the critical path to enabling a paradigm change depends most acutely on timeliness.

The present paper describes the role and technical details of a novel mesh paradigm that bridges a key technology gap on the path to realization of this vision. The paradigm is referred to as “strand mesh”. The paper introduces the strand mesh paradigm in context of a major multi-disciplinary, physics-based simulation software development project and an outline of the planned progression of capability development. Attributes of the mesh paradigm that warrant critical path designation are described along with key technology dependencies. The paper includes examples and a brief set of applications.

1 CREATE-AV Project Manager / IPA (University of Alabama at Birmingham), Associate Fellow AIAA

• Dr. Jack McNamara
• The Ohio State University
• 108 Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Sept. 3, 2012 – Sustained, reusable hypersonic platforms have tantalized the research community for over 60 years. A significant limiting factor to success is a lack of understanding of the interaction of a vehicle with the extreme hypersonic environment. This has necessitated the use of high levels of conservatism when designing the structural system, leading to excessive weight penalties that prevent a responsive flight system. This seminar will discuss recent research aimed at increasing the scientific understanding of energy transfer between the structure and a hypersonic operating environment.

Aug. 6, 2012 – Speaker: Prof. Russell Cummings
Modeling and Simulation Research Center, U.S. Air Force Academy, Colorado

A new approach for computing the unsteady and nonlinear aerodynamic loads acting on a maneuvering aircraft is presented. This approach is based on Duhamel’s superposition integral using indicial (step) response functions. The novelty of this approach relies on the development of a time-dependent surrogate model that fits the relationship between flight conditions (Mach number and angle of attack) and indicial functions calculated from a limited number of simulations (samples). The aircraft studied in the current paper exhibit highly nonlinear roll moment and therefore a very large number of step functions need to be calculated to accurately predict the aerodynamic behavior at each instant of time spent in aircraft maneuvers. The reduced order model, along with the surrogate model, provide a mean for rapid calculation of step functions and predicting aerodynamic forces and moments during maneuvering flight. The maneuvers are generated using a time-optimal prediction code with the feasible solutions based on the vehicle control and state constraints. Results presented show that the developed surrogate model aids in reducing the overall computational cost to develop cost-effective reduced-order models. It is also demonstrated that the reduced order model used can accurately predict time-marching solutions of maneuvering aircraft, but with an advantage that reduced order model predictions only require on the order of a few seconds of computational time.

• Dr. Heng Xiao
• Institute of Fluid Dynamics
• 221 Randolph Hall
• 4:00 p.m.
• Faculty Host: Dr. Alan Brown

May 17, 2012 – Large-Eddy Simulation (LES) has gained successes in the past decades, particularly for free-shear flows. In wall-bounded flows, however, the computational cost of LES is very high in order to resolve the near-wall features. This is a major hurdle for the application of LES in industrial and practical flows.

In this talk, I will present a consistent hybrid framework for turbulence modeling. In this framework, the filtered equations and the Reynolds averaged Navier-Stokes (RANS) equations are solved simultaneously in the whole domain on their respective meshes. Consistency between the two solutions is achieved through additional drift forcing terms in the corresponding equations. Compared to current methods in the literature, this approach leads to very clean conditions at the LES/RANS interfaces. The results demonstrate that the hybrid solver leads to significantly improved results with minor computational overhead compared to traditional LES, making it a promising candidate for industrial flow simulations. On going development include: (1) coupling with high-accuracy Cartesian LES solvers, (2) application to more complex flow (e.g. flow around cylinder), and (3) using more advanced turbulence models such as Reynolds Stress Transport Models.

• Dr. Goetz Bramesfeld
• Saint Louis University
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

April 30, 2012 – The fact that UAVs can fly missions otherwise not feasible for manned aircraft, for example because of long durations or risky environments, has made such vehicles very popular among the U.S. Armed Forces. Although a missing regulatory body hampers the civilian/commercial application of UAVs, this is about to change with very recent legislative developments. It is for certain that by the end of this decade, we will see the wide application of UAVs for civilian and commercial purposes, often with missions that we can barely imagine right now. Small and micro aerial vehicles will clearly be an important part of this future development, primarily due to their low kinetic energy, thus less damage to others in cases of accidents, and the continuation of miniaturization of electronics, which enables even smaller and more powerful sensors. Nevertheless, in order to augment the performance of small UAVs and MAVs innovative approaches are needed to increase the utility of such vehicles. For the past ten years, Dr. Bramesfeld has been working on improving the aerodynamics and flight performance of small UAVs. This work includes the design and testing of a "foam-it-up" small UAV that is a highly portable, testing of passive high-lift enhancement devices, optimizing MAVs for indoor flight, and modeling the interaction of structures and aerodynamics.

• Dr. Seongim Choi
• Korea Advanced Institute of Science and Technology
• 261 Durham Hall
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

April 19, 2012 – This talk focuses on the development and application of the state-of-the-art design optimization methodologies in aerospace vehicle design. Through the design applications of both fixed and rotary wing vehicle designs, numerous aspects of design optimization methods are introduced and compared. First, multi-fidelity and multidisciplinary design optimization method for supersonic business jets (SBJ) is introduced. Optimal shape and mission profile of SBJ are sought to reduce sonic boom on the ground while increasing aerodynamic performance. Second, a new design methodology is introduced for helicopter rotor design at unsteady forward flight. Unlike the fixed wing vehicle design, numerous difficulties are associated with the accurate prediction and design of unsteady rotor flows. A time-spectral and adjoint-based analysis and design method is introduced. The time-spectral method is based on the frequency-domain method that reduces the unsteady form of the NS governing equation to the periodic steady state formulation. A powerful adjoint solution method can be effectively integrated into the unsteady design framework for helicopter rotors. The design framework of time-spectral and adjoint-based method can be applied to many areas of the engineering design problems such as wind-turbine blade design and flapping wing MAV design.

• Dr. Bernd Chudoba
• The University of Texas at Arlington
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

April 16, 2012 – Abstract:

The motivation for this presentation is best summarized in the words of Brockway McMillan, Undersecretary of the Air Force: "The gap I refer to is the planning gap -- our failure to answer adequately the question I just asked ... we don't spend enough time, energy, or talent in deciding how to deploy our technological resources -- in other words, in deciding what to develop out of the products of our research" (Aerospace Management, Feb. 1964, p. 62).

The development of subsonic to hypersonic aircraft and space vehicles starts with the strategic conceptual design phase. The conceptual design phase itself can be subdivided into three distinct sub-phases: (a) parametric sizing, (b) configuration layout, and (c) configuration evaluation. Of these phases, parametric sizing represents the domain of the strategist and forecaster. This key phase is often misunderstood thus underrepresented due to its abstract nature amongst the multi-disciplinary sciences. This early screening capability identifies the correct design mission thus business case, it is used to develop aerospace infrastructure architectures and technology roadmaps; finally it represents the primary product definition step. This parametric sizing mindset and toolset is employed in propriety future projects environments like Lockheed Martin Skunk Works/ADP, Boeing Phantom Works, Airbus FPO, and others. Since the important strategic and managerial decisions occur early during a project, the quality of the parametric sizing implementation is crucial.

Today, detailed design investigations of aircraft and space vehicles are conveniently performed by the ‘technologist’ with an emphasis on increasing the level of accuracy for a given point-design whilst consuming most of the budget and development time. In contrast, the primary vehicle design decisions during the earlier conceptual design phase are still made by the ‘integrator’, often using over-simplified analyses and heuristics in a short amount of time. Note that the integrator or conceptual designer is responsible for identifying the correct solution-space topography containing candidate point-designs. This presentation introduces the primary elements to be required by any competitive aerospace future projects team focusing on quality decision-making. The resulting 21^st century aerospace product development capability delivers multi-disciplinary solution-space topographies to the decision-maker, integrator, and technologist, overall aimed at reducing cost, risk, and development spans.

• Dr. Pradeep Raj
• Independent Consultant
• 310 ICTAS
• 12:00 noon
• Faculty Host: Dr. Rakesh Kapania

April 12, 2012 – Computational Fluid Dynamics (CFD) capabilities for flow analysis have evolved from simplified geometry, simplified physics models of the late sixties and early seventies to complex geometry, sophisticated physics models used routinely today. In the early years, some experts unrealistically expected CFD to displace and supplant wind tunnels for producing aerodynamic data for aircraft design—characterized by this author as irrational exuberance. However, even after more than three decades of dramatic advancements, the full potential benefits of CFD elude us; it continues to serve as an able complement to wind tunnels. Our inability to produce credible computational predictions is the primary cause of this predicament—a sobering reality indeed. Going forward, it is essential that we focus our energies on correcting this situation because ability to produce credible data using CFD is the cornerstone of a promising strategy for successfully tackling the affordability challenge: developing technologically superior aircraft at affordable cost.

Simulation Based Design (SBD) offers a promising strategy for tackling the affordability challenge by rectifying the deficiencies of the traditional design practices. The deficiencies can be traced to a heavy reliance on experimental tests to generate data for configuration design and on developing physical prototypes to verify functional and operational characteristics which render the entire development effort too long and too expensive to meet customer expectations. A SBD effort employs integrated multi-disciplinary models, computational simulations, and simulators to guide the development of a virtual prototype (VP) with a degree of functional realism comparable to a physical prototype. The key measure of success is the level of fidelity with which a VP reproduces the characteristics of the real airplane. Clearly, realistic predictions of the requisite characteristics hold the key to success. And generating realistic predictions requires increasingly sophisticated high-fidelity physics-based modeling & simulation methods that exploit the ever increasing power of high-performance computers.

CFD plays a pivotal role in realizing the full potential benefits of SBD. CFD provides aerodynamic forces, moments and stability & control parameters required to assess VP performance to ensure that the final design will be capable of successfully carrying out the intended mission. Also, CFD provides inputs to several other engineering disciplines supporting the design effort. For example, airframe structural design requires steady and unsteady loads that CFD can provide. Flight control system design requires airplane response to control commands, and CFD can provide incremental forces and moments due to control surface deployment. In addition, CFD can provide on- and off-body data for an improved understanding of the flow features which offers valuable guidance for design modifications. It is worth noting that there is one design activity, namely, shape optimization, for which CFD is uniquely suited whereas any experimental testing based approach is totally inadequate. Of course, the key to success is: credible data.

• Dr. Eric Paterson
• The Pennsylvania State University
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Roger Simpson

April 9, 2012 – Over the past 10 years at Pennsylvania State University, I have established a diverse and vibrant research program in the fields of naval hydrodynamics, wind and hydro power, chemical trace detection, and cardiovascular devices. There are several common threads woven between these projects which I will expand upon in this talk, including: collaborative team research; complementary experiments, theory, and computer modeling; computational multi-physics and high-performance computing; and the importance of core fluid-dynamics competency. While the discussion will be aimed at the level of a programmatic overview, I will summarize some of the key technical contributions and broader impact of my work. To conclude the seminar, I will discuss academic leadership, the AOE strategic plan, and my vision for the department achieving its goals in education and research associated with atmospheric, ocean, and space vehicles.

• Dr. James Hubbard
• University of Maryland
• 261 Durham Hall
• 4:00 p.m.
• Faculty Host: Dr. Roger Simpson

April 5, 2012 – The Morpheus Laboratory at the National Institute of Aerospace has a strategic interest in pursuing a set of critical technologies and feasibility studies that establish a foundation for the future development of a practical organic aircraft. The technologies to be developed address the critical feasibility issues of 1) highly flexible multifunctional morphing structures, 2) vehicle lift generation and control, 3) civil applications for multiple coordinated organic aircraft, and 4) the development of a practical integrated vehicle system.

An organic aircraft, which makes use of biological and evolutionary approaches to flight, has the potential to make many long-envisioned uses for autonomous air vehicles a reality. Within two decades, an organic vehicle may uniquely serve a civil aeronautics market niche by being safe enough, quiet enough, and agile enough to work in close proximity to people and property. It also offers significant potential for flight within extraterrestrial atmospheres, thereby providing a practical means of extensive planetary exploration. The future vehicle is envisioned as shown in the figure. Terrestrial versions would have a wingspan of about four feet.

The organic aircraft would be ecologically neutral, creating no emissions. It will use highly flexible materials that enable the generation of lift and thrust without the need for bearings, linkages, or a separate propulsion system. Its multifunctional materials will improve flight efficiency. Its wings will gather and store energy, serve as an antenna, and host embedded sensors. The wings will generate lift and thrust through complex motions that actively adapt to the environment, guided by evolutionary computer algorithms. The aircraft will be capable of large configuration changes to create a wide flight envelope, from perching and hovering to high-speed tucked-wing dives. It would be intelligent, thereby enabling autonomous operations. Through advanced sensors, many of which would be integral to the multi-function materials used, it would adapt to changes in its health or its environment, offering protection to itself and to those around it if failures occur. It will communicate with a larger system of vehicles and carry out coordinated multi-vehicle missions that are impossible today. Terrestrial missions may include search and rescue, neighborhood security, large-scale atmosphere sampling, and the detailed inspection of large structures.

Dr. Hubbard, Director and Founder of the Morpheus Laboratory, will present an overview of research results from Project Firefly. These results include new smart skin sensors, passive and active wing morphing architectures, advances in state space modeling of flapping wing vehicles for robust. Project Firefly is a flight based program to ultimately develop a solid state ornithopter for civil applications that include search and rescue, atmospheric data collection, wild fire fighting, and crop surveys.

• Dr. Farhan Gandhi
• The Pennsylvania State University
• 4:15 p.m.
• 118C Surge Building
• Faculty Host: Dr. Roger Simpson

March 26, 2012 – In this seminar, Prof. Farhan Gandhi will speak on two recent areas of research activity. The first is the area of helicopter rotor morphing, which can result in envelope expansion, performance improvement and increased operational flexibility of the helicopter. In particular research on rotor span morphing, chord extension and twist morphing will be presented, along with discussions on the rationale for the selections and approaches. The second is the area of adaptive cellular structures. Prof. Gandhi's research group has examined both conventional and novel topologies (including zero Poisson's ratio and multi-stable cellular structures) for a wide variety of applications including energy absorption, morphing, and high stiffness and simultaneously high damping.

• Dr. Dewey H. Hodges
• Georgia Institute of Technology
• 261 Durham Hall
• 4:15 p.m.
• Faculty Host: Dr. Roger Simpson

March 22, 2012 – In modeling of structures with one dimension significantly larger (or smaller) than the other two, one can reduce the complexity of the resulting analysis by taking advantage of inherent small parameters. This results in reduced-dimensional models, such as beams (or plates/shells), and a much simpler mathematical formulation that helps to save computational costs. With the advent of composites and structural members with initial twist/curvature, particularly in the field of aerospace engineering, using beam, plate or shell theories based on traditional approaches and ideas will not yield accurate results. The variational-asymptotic-method (VAM) provides a mathematically rigorous way to reduce the 3D problem into a 1D beam-like (or 2D plate/shell) but without a priori assumptions such as "plane sections remain plane" or other oversimplifications. In this seminar, an overview of VAM is presented along with a description of how it can be used to develop reduced-order models for beams, plates and shells. The results are verified for test cases by comparisons with 3D solutions or 3D FEM results.

• Dr. James Tangorra
• Drexel University
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Michael Philen

Feb. 27, 2012 – Bony fish swim with a level of agility that is unmatched in human-developed underwater systems. This is due, in large part, to the ability of fish to carefully control hydrodynamic forces through the sensory based modulation of the fins' kinematics and mechanical properties. To better understand how fish produce and control forces, biorobotic models of the bluegill sunfish's (Lepomis macrochirus) caudal and pectoral fins, and of the pectoral fin's sensory and control systems have been developed. The designs of these systems were based on detailed analyses of the anatomy, kinematics, and hydrodynamics of the biological fins and on neuromechanical studies of the sensory systems intrinsic to the biological fins. These models have been used to investigate how fin kinematics and mechanical properties influence propulsive forces and to understand how sensory information gathered about the fin and the flow relates to fin performance.

• Dr. Sang-Eon Chun
• Samsung Heavy Industries, Ltd.
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Feb. 6, 2012 –

Sloshing remains an issue for LNG (Liquefied Natural Gas) industry, particularly for LNG tankers and FPSO/FSRU, etc., with membrane-type LNG CCS (Cargo Containment System), which use the hull structure as the load bearing tank body and have the relatively soft insulation material between the LNG cargo and the hull structure. The insulation material structure is adopted only to maintain the low temperature inside the tank and to protect the hull structure from being exposed to the critically low temperature. If the baffle plates are introduced to reduce the sloshing motion inside the LNG tanks, it is unavoidable to support them onto the load bearing hull structure, which inevitably leads to heat paths and deteriorates the insulation performance of the LNG CCS. Therefore, the sloshing issues in the membrane-type LNG CCS are partially treated by adopting the octagonal shape to reduce the impact load due to sloshing motion and reinforcing the insulating structures of LNG CCS, which is supposed to be constrained by economic and technical limitations. In spite of these design changes, the sloshing concern relating to possible damages on the CCS is still limiting the operating conditions and so the new business chances; LNG tankers are allowed to operate with the LNG cargo filled more than 80% or less than 10% of the tank height.

In this paper, a unique and innovative solution to the sloshing conundrum, named as ABAS (Anti Boil-off gas Anti Slosh) blanket system, is unveiled, which can dampen the motion of LNG inside the LNG cargo vessels in operation in a cheap and effective way and, as a result, the sloshing loads on CCS can be reduced significantly. This design concept has been proved through various sloshing model tests, which show the dramatic reduction of sloshing motion. Finally, the production of prototypes of floating unit structures which are assembled into a floating blanket layer, ABAS blanket system, shows the applicability in real LNG vessels.

And in conclusion, the speaker will share his own experiences to solve the technical issues based on the Seven Da Vincian principles in the book of How to Think like Leonardo Da Vinci written by Michael Gelb.

• Dr. Stefan Siegel
• Atargis Energy Corporation
• 211 Randolph Hall
• 2:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Feb. 1, 2012 – This presentation introduces a novel ocean wave energy converter (WEC), namely, a Cycloidal turbine, as a wave termination device. A Cycloidal turbine employs the same geometry as the well-established Cycloidal or Voith-Schneider Propeller. The main shaft is aligned parallel to the wave crests and fully submerged at a fixed depth. We show that the geometry of the Cycloidal WEC is suitable for single sided wave generation as well as wave termination of straight crested waves using feedback control. The Cycloidal WEC consists of a shaft and one or more hydrofoils that are attached eccentrically to the main shaft. An experimental and numerical investigation into the wave generation capabilities of the WEC are presented in this paper, along with wave cancellation results for deep water waves. The experiments are conducted in a small 2D wave flume equipped with a flap type wave maker as well as a 1:4 sloped beach. The operation of the Cycloidal WEC both as a wave generator as well as a wave energy converter interacting with a linear Airy wave is demonstrated. The influence that design parameters radius and submergence depth on the performance of the WEC have is shown. For wave cancellation, the incoming wave is reduced in amplitude by ≈ 80%in these experiments. In this case wave termination efficiencies of up to 95% of the incoming wave energy with neglegible harmonic waves generated are achieved by synchronizing the rotational rate and phase of the Cycloidal WEC to the incoming wave.

• Dr. Guoming (George) Zhu
• Michigan State University
• 118C Surge Building
• 4:00 p.m.
• Faculty Host: Dr. Cornel Sultan

Jan. 30, 2012 – The output covariance constraint (OCC) problem will be introduced with both deterministic and stochastic interpretations. A control design algorithm with guaranteed convergence will also be presented with application to the pointing control of the Hubble Space Telescope. Note that with the scalar output covariance constraints, the solution of the OCC problem also provides an optimal control for the constrained H₂ problem. Next, the talk will address the output H₂ weight tuning for the mixed H₂/H∞ LPV (linear parameter variation) control problem for polytopic discrete time LPV systems. By properly selecting the output H₂ weighting, multiple performance constraints on the output H₂ norms are met while minimizing the H₂ control effort. Normally, the output H₂ weighting is selected in an ad hoc manner for the mixed H₂/H∞ LPV control problem. The iterative algorithm provides a way to find the output H₂ weighting such that the designed mixed H₂/H∞ LPV controller satisfies the performance constraints. An illustrative example will be presented to demonstrate the effectiveness of the iterative algorithm.

• Dr. Serge Prudhomme
• Institute for Computational Engineering and Sciences (ICES)
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Christopher Roy

Dec. 5, 2011 – Finite Element methods are widely used today for the solution of boundary- and initial-value problems of scientific and engineering interest. However, these methods, as with any other numerical methods, only provide approximations of the true solutions, which, therefore, inevitably contain errors due to the discretizations in space and time. In this talk, we will describe in detail adjoint-based techniques for a posteriori estimation and adaptive control of the discretization errors, measured with respect to quantities of interest. These so-called goal-oriented error estimation methods will be illustrated on a series of model examples, ranging from linear elliptic problems to nonlinear and time-dependent problems. We will also show how one can extend these methods to the case of coupled problems and how one can design adaptive methods for optimal control of the discretization error in the quantities of interest.

• Dr. Geir Dullerud
• University of Illinois at Urbana-Champaign
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Mazen Farhood

Nov. 14, 2011 – This seminar finds its basis in mathematically grounded questions about collaboration and control in multi-agent dynamical systems. It is inspired from a practical perspective by recent advances in sensing, computing and networking hardware that make reconfigurable multi-agent systems both technologically and economically feasible on a widespread scale. Examples of such systems include satellite formations, consumer robotics, and more generally networked subsystems of mobile sensors and actuators that cooperate to achieve some aggregate functionality. There are many shared design challenges associated with these types of systems, and the talk will focus on two specific issues: (1) switched hybrid dynamics; and (2) network latency and multi-resolution sensing for control. The technical setting for the talk is the framework of convex optimization, and the results presented lead directly to implementable analysis and design algorithms via semidefinite programming. In part of the work presented on switched dynamics, we will as a special case provide an exact solution to a long-studied receding horizon problem, the first exact solution to this problem to our knowledge. A portion of the presentation will be devoted to describing the experimental multi-vehicle testbed, HoTGames, which consists of wirelessly linked miniature hovercraft, quad-rotor helicopters and wheeled vehicles all capable of onboard multi-modal sensing, and interaction with the Internet and a vision-based sensor network.

• Dr. Matthew Oehlschlaeger
• Rensselaer Polytechnic Institute
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Lin Ma

Nov. 7, 2011 –

Gas-phase autoignition, the topic of the first half of this seminar, and its underlying reaction kinetics are of fundamental importance to the operation of combustion-based aero-propulsion engines, particularly in advanced engine concepts where kinetics is of greater importance than in legacy designs. The increasing significance of kinetics in modern engine operation and the rapid development of alternative fuels from biomass and other sources motivates a science-based understanding of reaction kinetics and in particular the influence of fuel structure and composition on oxidation and autoignition. The results of shock tube autoignition studies for low volatility conventional and alternative aviation fuels and components under wide-ranging conditions will be discussed. These studies provide: 1) fundamental information about the structure-reactivity relationships for fuels, 2) targets for the development of fuel oxidation kinetic models, 3) assessment of simplified surrogate mixtures designed to mimic the behavior of real fuels and the methodologies used for their formulation, and 4) information that can be used in the design and development of combustors.

In the second half of the seminar exploratory efforts to use the photoignition of nanomaterials dispersed in fuel/oxidizer mixtures to manipulate ignition and combustion wave propagation will be presented. Initial results show that photoignition can be used to achieve quasi-homogenous ignition of gaseous fuel/air/nanomaterial mixtures and reduce flame acceleration and deflagration-to-detonation time and length scales by around a factor of two.

• Mr. Philip Van Seeters
• Boeing Commercial Airplanes
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Rakesh Kapania

Oct. 17, 2011 – An airplane is the compromise of the reaction to a wealth of requirements and the product of numerous disciplines and systems interacting in unison and harmony. The airplane designer's responsibility is to synthesize all requirements and disciplines to arrive at an integrated solution. Successful design engineers carry a set of fundamental tools which help them understand the impact on the integrated vehicle that result from (changes to) a given system. But like any tool, the tool is only as good as its user. One such tool is the payload-range diagram; it communicates mission capabilities and is sensitive to weight changes, aerodynamic efficiency, and propulsion efficiency. It can be used to tailor a vehicle to a range of missions, and is useful in devising a family plan of aircraft. This seminar will dive into the nuts and bolts of the payload-range diagram and focuses on the application to commercial aircraft.

• Dr. Luciano Castillo
• Texas Tech University
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. William Devenport

Oct. 10, 2011 – Although wind turbines have been well studied from a blade aerodynamics perspective, the interactions among these massive structures and the atmospheric turbulent boundary layer (ATBL) are still not understood in detail. It is important to understand such interactions in order to maximize the energy that can be extracted from the available wind resource. Past investigations have determined that wind turbines that operate within an array can display a significant power generation loss, when compared to a freestanding wind turbine. Thus, their ability to extract kinetic energy from the flow decreases due to complex interactions among them, the terrain topography and the atmospheric boundary layer.

In order to improve the understanding of the vertical transport of momentum and kinetic energy across a boundary layer flow with wind turbines, wind-tunnel experiments were performed to include: a single wind turbine blade, a single wind turbine and a scaled down wind array. The boundary layer flow includes a 3 X 3 array of model wind turbines. Particle-image-velocity measurements in a volume surrounding a target wind turbine are used to compute mean velocity and turbulence properties averaged on horizontal planes. The impact of vertical transport of kinetic energy due to turbulence and mean flow correlations is quantified. It is found that the fluxes of kinetic energy associated with the Reynolds shear stresses are of the same order of magnitude as the power extracted by the wind turbines, highlighting the importance of vertical transport of turbulence in the boundary layer and thus in wind farms. Moreover, the streamtube is visualized in a single wind turbine in order to gain insight into the flow and to test the axisymmetric assumption used for the calculation of the induction factor. Results show that the streamtube is indeed close to axisymmetric, but exhibits some slight distortions due to strong tower effects and shear from the wall.

• Dr. Andrew Sinclair
• Auburn University
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Troy Henderson

Oct. 3, 2011 – Abstract: TBA

• Dr. David Poling
• Deputy Program Manager
• Joint Multi Role Program, Boeing
• 1060 Torgersen Hall
• 7:30 - 8:00 p.m.
• Sponsored by the AOE Advisory Board with AIAA, ASNE, SNAME, and SGT.

Sept. 29, 2011 – Topic: Boeing Company Overview.

• Ms. Kristin Swift
• Principal Deputy Director
• USN and USMC Airworthiness Directorate at Naval Air Systems Command
• 1060 Torgersen Hall
• 7:00 - 7:30 p.m.
• Sponsored by the AOE Advisory Board with AIAA, ASNE, SNAME, and SGT.

Sept. 29, 2011 – Topic: Women in Military Aviation.

• Mr. Bob Hanley
• Director
• USN and USMC Airworthiness Directorate at Naval Air Systems Command
• 1060 Torgersen Hall
• 6:30 - 7:00 p.m.
• Sponsored by the AOE Advisory Board with AIAA, ASNE, SNAME, and SGT.

Sept. 29, 2011 – Topic: Airworthiness Certification and Initial Fleet Introduction of the F-35 Lighting Joint Strike Fighter.

• Dr. Umesh Vaidya
• Iowa State University
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Cornel Sultan

Sept. 26, 2011 – Analysis and control of uncertain nonlinear systems exhibiting non-equilibrium dynamics is of interest in various applications such as fluid flow control, electric power grid, and biological systems. In this talk we present results on the novel ergodic theory-based framework for the analysis and control of non-equilibrium dynamics in uncertain dynamical systems. Our first main result is on the introduction of Lyapunov measure as a new tool for stability verification and stabilization of non-equilibrium dynamics in nonlinear systems. The main contribution of this work is that it provides for a systematic linear programming based solution for the stability verification and stabilization of nonequilibrium dynamics in nonlinear systems. The novel framework is also used to study the problems of stabilization and estimation of nonlinear systems over uncertain channels and interconnections. The main results prove that fundamental limitations arise in the stabilization and estimation of nonlinear systems over uncertain channels, expressed in terms of channel uncertainty and positive Lyapunov exponents of the open loop nonlinear system. The positive Lyapunov exponents capture the global instability of nonlinear systems. Hence our results highlights, for the first time, the important role-played by the global nonequilibrium dynamics in obtaining the limitation results. The framework is extendable to study more general control problems over uncertain networks with nonlinear components dynamics.

• Mr. Alex Sang
• Luna Technologies
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Christopher Roy

Sept. 19, 2011 – The ability to make numerous, distributed measurements in a single, standard optical fiber makes fiber-optic sensing a practical and financially attractive alternative to conventional methods. We present a novel technique for high resolution distributed fiber-optic strain and temperature sensing based on measuring spectral shifts in the Rayleigh backscatter along an optical fiber. High-sensitivity Optical Frequency Domain Reflectometry (OFDR) is used to measure the scatter continuously along the fiber with sub-cm spatial resolution. Distributed measurements of strain and temperature in off-the-shelf telecommunications grade fiber are demonstrated for composite cure monitoring, wind turbine defect detection and structural health monitoring, and crack detection in concrete. This presentation will also include a live demonstration of distributed sensing measurement on a test article.

• Dr. William Whitacre
• Northrop Grumman
• 113 McBryde Hall
• 4:00 p.m.
• Faculty Host: Dr. Craig Woolsey

Sept. 5, 2011 – Geolocation is the process of using sensor data to develop statistical estimates of a point of interest (POI) on the ground. When using uninhabited aerial vehicles (UAVs) with gimballing cameras, each UAV, based on its position and orientation, points the camera (through a gimballing payload mount inside the UAV) at the POI on the ground. While the aircraft is moving, and the POI is potentially moving, the camera gimbals must adjust their angles such that the POI always remains within the field of view of the camera. The objective of geolocation is then to estimate the position (2D or 3D) of the POI. Complicating this problem are uncertainties in the aircraft position and orientation, gimbal angles, camera specifications and measurements, and disturbances such as turbulence and engine vibrations.

This presentation will cover four important topics for cooperative geolocation:
1. Decentralized estimation algorithm - A decentralized filtering approach is shown for geolocation that provides tracking accuracy and is further scalable with the number of UAVs

2. Decentralized bias estimation - In practice, there are non zero mean errors (biases), which degrade geolocation accuracy. Therefore, a decentralized approach is developed to simultaneously estimate the unknown location of the POI as well as the biases of each UAV.

3. Methods for communication loss and delay - Communication is an important part of a cooperative geolocation mission. However, in practice, communication losses and delays are inevitable. Therefore, a new method for cooperative geolocation in the presence of communication loss, termed the predicted information method, is developed.

4. Orbit optimization - The optimization of periodic orbits for tracking both stationary and moving targets with two uninhabited aerial vehicles is considered. A natural metric that takes into account the fact that the orbits are periodic, is used and three key results are obtained.

Flight tests with the ScanEagle UAV made by Insitu Inc. will be shown to validate each of the algorithms presented.

• Dr. Mason Peck
• Cornell University
• Holden Auditorium
• 4:00 p.m.

May 9, 2011 – There is untapped potential for transformative spacecraft missions that use very small, agile satellites. This talk considers the mission-performance benefits and systems-engineering challenges of small length scale from the perspective of attitude-dynamics fundamentals. Violet is a 50 kg agile spacecraft with an optical payload being developed by faculty and students in the Space Systems Design Studio at Cornell University. Dr. Peck will describe Violet’s objectives and system architecture as a case study of this principle and will offer some details on its attitude control subsystem. He will also discuss the design and dynamics of very small control-moment gyroscopes (CMGs). As a nanosatellite, Violet exhibits structural dynamics that are much higher in frequency than larger spacecraft with analogous mission objectives. For this reason, among others, the spacecraft’s eight 0.3 Nm / 0.3 Nms CMGs can be used with comparatively high-bandwidth attitude control to provide extraordinary agility of at least 10 deg/sec, 10 deg/sec^2, and 60 deg/sec^3, with the prospect of as much as four times as much depending on the power available. Mission applications include remote sensing, space situational awareness, and in-orbit inspection and repair of other spacecraft. This general principle, exploiting the dynamics of small-scale vehicles, may motivate even smaller spacecraft. Dr. Peck will discuss some future directions for this research that include centimeter-size spacecraft with surprising orbit mechanics.

• Dr. Rob McDonald
• California Polytechnic State University
• 104D Surge Building
• 10:05 a.m.

May 6, 2011 – Advanced multidisciplinary physics-based design and analysis capabilities are required to pursue the revolutionary vehicle and technology concepts needed to meet the substantial challenges facing the aerospace community. An aircraft’s shape is the natural starting point for physics-based multidisciplinary analysis and optimization. Its outer mold lines and structural layout are the interface between aerodynamics, structures, mass properties, and all the physics that impact a vehicle’s performance.

The decision makers involved in the design of the next generations of air vehicles need the ability to select and vary the level of analysis fidelity to suit the decision being made. Unfortunately, analysis fidelity is often dictated by the available tools. This limitation frequently stems from the underlying geometry representation.

NASA’s Vehicle Sketch Pad (VSP) is a parametric geometry tool which presents the opportunity to dramatically change the way design is performed. Planned research will result in a geometry engine and an integration framework which are significantly more intelligent, more extensible, and more capable that what is available today. These tools will enable multi-fidelity and multi-physics analysis early in the design process when fundamental decisions are made. This improved design modeling capability will lead to better understanding of the advanced technologies and concepts required to meet the challenges facing the aerospace industry.

• Dr. Mark Costello
• Georgia Tech
• 1060 Torgersen Hall
• 10:05 a.m.

May 4, 2011 – Given the availability of highly capable computers, algorithms, sensors and actuators, there exists a terrific opportunity for innovation in the design of air vehicle configurations and components to solve pressing practical problems. This talk will focus on two such practical problems and potential solutions recently developed by the Costello Research Group at Georgia Tech. The first problem considered is traversing complex man-made or naturally occurring interior spaces over long periods of time. A new micro rotorcraft was created consisting of a caged coaxial rotor system with an inherent low mass center that is controlled with an internal translating mass. The motivation, development, and performance of this vehicle configuration will be detailed. The second problem involves accurately landing an air dropped payload under a parafoil canopy to within meters of an intended ground impact point. Several new longitudinal glide slope control mechanisms have been invented including dynamic rigging of the canopy in flight as well as using canopy bleed air to construct a virtual aerodynamic spoiler. The talk will conclude with a discussion of the key elements of air vehicle design in the university environment.

• Dr. James Cutler
• University of Michigan
• Holden Auditorium
• 4:00 p.m.

May 2, 2011 – Nanosatellites are proving to be a useful tool for increasing our capabilities in space flight, space exploration, and space science. For example, at the University of Michigan, we have recently built and launched the National Science Foundation's (NSF) first nanosatellite mission, the Radio Aurora Explorer. RAX is the first of seven missions funded by the NSF to explore space weather through novel experiments and space missions. RAX is a bistatic radar mission to measure ionospheric disturbances at polar latitudes. In this talk, we will discuss the several nanosatellite missions under development at the University of Michigan. Our first mission, RAX, was launched in November 2010 and demonstrated successful bistatic radar measurements. We will also describe our research program focused on design and operation optimization of nanosatellite missions.

• Dr. Lin Ma
• Clemson University
• 1060 Torgersen Hall
• 10:05 a.m.

April 25, 2011 – The study of modern propulsion systems calls for innovative and effective experimental methods. This talk describes our efforts to develop such methods and apply them to study modern propulsion devices. A suite of advanced laser diagnostics has been developed to address the experimental challenges posed by modern propulsion systems, including the extreme temperature and pressure, highly transient physiochemical processes, control and stability issues, and multi-phase environment. This talk focuses on three topics to illustrate the unique opportunities enabled by these diagnostics for propulsion research: 1) the study of the control and stability of propulsion devices using absorption spectroscopy, 2) the study of dense fuel sprays using ballistic imaging, and 3) the study of fundamental turbulent combustion using particle image velocimetry and photodissociation spectroscopy. The applications of these topics in other cross-disciplinary areas will also be discussed.

• Dr. Jack Edwards
• North Carolina State University
• 1060 Torgersen Hall
• 10:05 a.m.

April 18, 2011 – The design and analysis of high-speed aeropropulsion concepts requires a fundamental accounting of unsteady flow behavior as induced by shock / viscous layer interactions, fuel injection and mixing, and combustion dynamics. This talk will discuss the development of several computational fluid dynamics techniques and modeling strategies suitable for high-fidelity analyses of such effects, both at a component level and as part of a ‘tip-to-tail’ simulation strategy. These include large-eddy / Reynolds-averaged Navier-Stokes simulation methods for wall-bounded turbulent flows in configurations influenced by multiple solid surfaces, phase-interface capturing techniques for simulating primary atomization, phase-transition modeling for supercritical fuels injection, and immersed-boundary methods for rendering of complicated, possibly moving, objects. Examples pertinent to compressible, reactive flows encountered in aero-propulsion systems will be presented, and future directions for research in this scope will be outlined.

• Dr. Liangyu Wang
• United Technologies Research Center
• 1060 Torgersen Hall
• 10:05 a.m.

April 11, 2011 – The need for predictive simulations of turbulent combustion becomes more and more urgent in practical device design and performance evaluation. In order to achieve predictive simulations, a range of involved physical and chemical phenomena must be taken into account. These phenomena include turbulent transport, finite-rate chemistry, multiphase flow, soot, thermal radiation, and combustion instability and dynamics. Furthermore, the nonlinear interactions among these physical and chemical processes, such as turbulence-chemistry-radiation interactions, must be modeled properly as well. In the first part of this talk various modeling issues in aeroengine combustor simulations will be discussed. As new combustor technologies emphasize on lean premixed combustion to meet more and more stringent emission regulations, modeling and simulations of liquid fuel injection, fuel air mixing in strong turbulent swirling flows, unsteady heat release, and thermal radiation become critical in the design, evaluation, and optimization of new combustor concepts. Research that has been done and recent development in these areas will be described. In the second part of this talk a recent study on the interactions of water mist with fire radiation will be described in detail. Next generation water mist systems are being developed to compete with multi-billion dollar sprinkler industry and to extend to residential markets. Thermal radiation affects vaporization rate of water mist and, therefore, the penetration and transport of water mist. Water mist and water vapor block radiation transfer to the surrounding walls and combustible materials and, therefore, suppress fire growth and spreading. Results from studying a canonical problem are discussed and key physics are identified for the interactions between fire radiations and water mist.

• Dr. Chi Yang
• George Mason University
• Holden Auditorium
• 4:00 p.m.

April 4, 2011 – With the rapid development of computer hardware and software, large-scale computational simulations are making significant contributions to many important areas of ship hydrodynamics. Computational Fluid Dynamics (CFD) in particular is proving to
be extremely useful in the hydrodynamic analysis and design of ships. The future of the CFD in ship hydrodynamics is to improve available CFD tools and integrate them in a comprehensive simulation environment to predict and study ship behaviors at sea and perform hydrodynamic design optimization of ship hulls.

An integrated graphic user interface (GUI) toolkit for ship hydrodynamic analysis and hull form optimization has been developed. The main components of this toolkit consist of a practical design-oriented simple CFD tool and an advanced CFD tool; a hull surface representation and modification module; and an optimization module. The simple CFD
tool can be used for the preliminary and early stages of the hydrodynamic design of hulls, and the advanced CFD tool for the detailed flow analysis at late stages of the hydrodynamic design of hulls. Both the simple CFD tool and the advanced CFD tool have been improved and further validated. New hull surface representation and modification techniques have been developed to allow both local and global modifications of the hull form with any given constraints during the hydrodynamic
optimization process. It can also be used to conduct parametric studies of the hull hydrodynamic performances. In addition, the new hull surface modification technique can be used to generate an initial hull form to satisfy the design needs first before
performing the optimization. Various optimization techniques are implemented in the optimization module to satisfy different optimization requirements. An overview of the recent advances in both the simple CFD tool and the advanced CFD tool, and the application of the toolkit to both single and multi-objective hydrodynamic optimization problems will be presented. The first version of the ship design and hull form optimization software will be introduced. This software can be further developed and enhanced, so that it can be used not only by naval architects for routine hull form design and hydrodynamic analysis, but also for the education of future naval architects.

• Dr. Adam Steinberg
• German Aerospace Center (DLR) Institute of Combustion Technology
• 1010 Torgersen Hall
• 10:05 a.m.

April 4, 2011 – The past several years have seen a great increase in gas turbine engine deployments, along with a concurrent demand for drastically reduced pollutant emissions. Effectively meeting these increasingly stringent emission targets has been hampered by the tendency of low-emission engines to exhibit self-excited and self-destructive thermo-acoustic instabilities. Such instabilities are driven by a complex flow-combustion-acoustic coupling, the prediction of which is not yet possible. Control schemes are therefore applied as a redesign or retrofit when unstable conditions are encountered in late-stage testing of new engines, at a great expense of time and money. Furthermore, since the instabilities are not fundamentally solved, they have a tendency to reappear when minor design upgrades or changes in fuel composition are made. However, our understanding and management of thermo-acoustic instabilities can be greatly aided by recent advances in high-repetition-rate laser-based flow and combustion diagnostics. This seminar will discuss a current research program that uses a suite of such diagnostics to better understand and predict how thermo-acoustic instabilities are excited in low-emission gas turbine combustors. A detailed analysis of the flow-combustion-acoustic coupling will be presented for a variety of swirl-stabilized flames. Due to the temporal resolution afforded by the diagnostics, quantification of previously unobserved and thermo-acoustically coupled flow-flame interaction dynamics is possible. Furthermore, by simultaneously resolving multiple periodic processes, the high-speed measurements provide a three-dimensional map of how energy is transferred between heat release and acoustic oscillations through such interactions. The understanding of thermo-acoustic energy transfer gained from this analysis has the potential not only to aid in avoiding unstable states, but to allow tailoring of combustors such that natural flow features provide an effective means of damping instabilities.

• Dr. Ratneshwar Jha
• Clarkson University
• 1060 Torgersen Hall
• 10:05 a.m.

March 23, 2011 – This presentation will focus on the technologies of smart structures and adaptive systems with applications to aircraft design. Smart structures technology has the potential to significantly impact numerous products in diverse industries such as aerospace, wind energy, and civil infrastructure. Recent research in the Smart Structures Laboratory at Clarkson University will be presented with particular emphasis on Lamb wave based health monitoring of aerospace composite structures. This research involves the development of damage detection algorithms through an understanding of structural mechanics, elastic wave propagation, and advanced signal processing. The use of wavelet based spectral finite elements (FE in frequency domain) for wave propagation in composite plates will be discussed. An overview of vibration based damage detection using proper orthogonal decomposition and Hilbert-Huang transform will be presented.

Adaptive control systems can maintain consistent performance of a system in the presence of uncertainty or unknown variation in plant parameters. A hybrid adaptive control scheme is designed as a launch vehicle flight controller for ascent phase of NASA Crew Launch Vehicle. The hybrid adaptive control approach augments linear feedback signals with contributions from both direct and indirect adaptive control elements. In addition, signal filters are incorporated into the feedback loop to prevent harmful interaction between the flight control system and structural bending modes. The performance of the hybrid adaptive flight controller is compared to that of a typical gain-scheduled linear feedback controller in a high-fidelity Ares I ascent simulator obtained from the NASA Marshall Space Flight Center. The hybrid controller shows superior performance compared to a traditional PID flight controller for both rigid and flexible cases. Applications of adaptive control for active vibration suppression and flow control will also be discussed briefly.

• Ms. Lauren Hunt
• Texas A&M University
• Holden Auditorium
• 4:00 p.m.

March 21, 2011 – Laminar Flow Control (LFC) techniques are used in air-vehicle design to delay the onset of boundary-layer transition, ultimately reducing fuel burn and improving aircraft efficiency. Delaying transition on a swept wing dominated by a
crossflow instability through the use of spanwise-periodic discrete roughness elements (DRE) has been successfully demonstrated both in ground and flight tests. However, the DRE effectiveness appears much more limited under flight conditions. The reason for the difference between wind tunnel and flight tests is not well understood, but a recently reactivated ground test capability may begin to explain these differences.

The low-disturbance Klebanoff-Saric Wind Tunnel was relocated from Arizona State University (ASU) to Texas A&M University (TAMU) in 2005. During its subsequent reconstruction, several component modifications were introduced to further enhance flow quality and experimental control. This talk discusses the changes made to the tunnel and the resulting flow-quality measurements. Final turbulence levels are compared to the ASU flow quality and the significance of these results is discussed in the context of an on-going crossflow instability experiment at TAMU using the ASU model. New stability and receptivity data and their implications for ongoing flight and wind tunnel tests are presented.

Acknowledgement: This work was supported by the NASA Aeronautics Scholarship Program and AFOSR Grant FA9550-08-1-0093.

• Dr. Timothy Takahashi
• Santa Clara University
• 1060 Torgersen Hall
• 10:05 a.m.

March 21, 2011 – This seminar will discuss several technology and design issues that impact the design of future commercial aviation, as well as military transport, strike, and combat aircraft. It will discuss:

1. How visualization of mission performance parameters as "point-performance" reveals how the actual, realizable performance of an airframe may be substantially lower than that implied by its peak aerodynamic efficiency, L/D.
2. How propulsion system loads and losses (that affect thrust levels) may have unintended consequences upon mission performance.
3. How using a true mission performance code (not Breguet’s equation) coupled to an aerodynamic thickness allocation scheme coupled to a medium-fidelity structural weight prediction scheme to perform a multi-disciplinary study reveals that the most aerodynamically favorable designs have the best system performance.

• Dr. David Finkleman
• Center for Space Standards and Innovation
• Holden Auditorium
• 4:00 p.m.

March 14, 2011 – This talk examines diverse approaches to representing gasdynamic drag effects on Low Earth Orbit (LEO) satellites. Although the total drag force on a satellite can be measured, the physics of gasdynamic resistance, dynamics of the orbiting body, and characteristics of the atmosphere are inextricably combined. Investigators must hypothesize physical relationships among the drag force, body shape, size, and orientation, the distribution of density, and the predictive assessment of density. Drag coefficients determined under one set of hypotheses are often employed improperly in orbital assessments that use a different set of hypotheses. Our goal is to consolidate the existing information, establish a framework for future research, and expose practical issues.

• Dr. Robert Niewoehner
• United States Naval Academy
• 1010 Torgersen Hall
• 10:00 a.m.

March 14, 2011 – Dr. Niewoehner’s first flight during the F/A-18 E/F’s development exposed a nightmare. Further testing revealed a strong transonic abrupt wing stall (“wing drop”) which nearly caused the technical collapse of the Super Hornet as a program.
Embarrassingly, the wind tunnel develop had provided advance clues, yet clues that no one in government or industry were prepared to properly interpret. Had those clues been seen by engineers of the 1950s, the problem would have been diagnosed long before first flight; the challenge was not new, but forgotten. A two-year effort, flown principally by Dr. Niewoehner, devised an imperfect fix. The airplane was fielded on time, and won laurels in battle, yet two questions remained. “Can we find a better fix?” “Can we avoid being surprised by this again?” A Navy/NASA/Industry effort was
funded by the Joint Strike Fighter office to better understand the phenomenology, including its historical impacts, and then develop diagnostics for mitigating the challenge in future designs. The F-35C now sports spoilers on its outboard wing panels
mitigating the risk of its appearance in that program’s design. This presentation will recount the history, findings, and applications of the study group’s work.

• Dr Rajkumar Pant
• Virginia Polytechnic Institute and State University
• Holden Auditorium
• 4:00 p.m.

Feb. 28, 2011 – Travelers on short haul routes demonstrate some very interesting trade-offs. Most passengers tend to prefer the mode that offers them the lowest Generalized Cost of travel (GCT), which represents the sum total of all the direct and indirect costs incurred. This talk will discuss a methodology for conceptual design and optimisation of twin-turboprop aircraft for short-haul business travel. GCT is considered to be the summation of costs related to the access to and from the airport (Access Cost), provision of the flight services (Flight Cost), money value of the total travel time (Time Cost), and costs associated with setting up and operating the airport (Airport Cost). An aircraft conceptual design and optimization problem is posed in terms of 17 design variables and nine constraints. The methodology obtains the configuration and flight profile of the aircraft and the associated airport infrastructure that meets the expected level of travel demand at the least possible GCT. The methodology can also be utilised to carry out a comparative analysis of the GCT of competing Commuter and Regional aircraft, to assess their suitability of operation over a particular route. As a demonstration of the application of this methodology, the results of two case studies for short-haul business air-travel in India are presented. These case studies illustrate the efficacy of this methodology for a systems-engineering based planning and analysis of an air transportation system.

• Dr. Umesh Vaidya
• Iowa State University
• Holden Auditorium
• 4:00 p.m.

Feb. 7, 2011 – Analysis and control of uncertain nonlinear systems exhibiting non-equilibrium dynamics is of interest in various applications such as fluid flow control, control of complex networks, and biological systems. In this talk we present
results on the novel ergodic theory-based framework for the analysis and control of non-equilibrium dynamics in uncertain dynamical systems. Our first main result is on the introduction of Lyapunov measure as a new tool for stability verification and stabilization of non-equilibrium dynamics in nonlinear systems. The main contribution of this work is that it provides for a systematic linear programming based solution for the stability verification and stabilization of non-equilibrium dynamics in nonlinear systems. The novel framework is also used to study the problems of stabilization and estimation of nonlinear systems over uncertain channels and interconnections. We show that fundamental limitations arise in the stabilization and estimation of nonlinear systems over uncertain channels, expressed in terms of variance of channel uncertainty and system instability. The main contribution of this work is that it highlights, for the first time, the important role-played by the global non-equilibrium dynamics in obtaining the limitation results. The framework is extendable to study more general control problems over uncertain networks with nonlinear components dynamics.

• Dr. Francis Aviles Cetina
• Centro de Investigacion Cientifica de Yucatan (CICY)
• Holden Auditorium
• 4:00 p.m.

Jan. 24, 2011 – This talk will discuss the use of multiwalled (MW) carbon nanotubes (CNTs) as elements for sensing strain and matrix damage in MWCNT-polymer composites. Experimental results will be discussed to demonstrate the high sensitivity to strain and damage of a percolating CNT network, once this has been formed inside the polymer matrix. Specific results of two material systems will be discussed, one that employs a thermoplastic matrix in thin film geometry, and a second one which employs a bulk thermosetting matrix. In addition, this talk will discuss the influence of multi-walled carbon nanotube (MWCNT) alignment into a polymer matrix on the electrical and piezoresistive properties of the resulting composites. An alternating current electric field is employed for MWCNT alignment, which is macroscopically evident in the crystallized polymer. Electrical conductivity and electromechanical sensitivity were improved in the direction of the aligned network. CNT/polymer composites were also tested under loading-unloading cycles, presenting good strain-sensing capabilities.

• Dr. Greg Young
• Naval Surface Warfare Center
• Faculty Host: Dr. Joseph Schetz
• Holden Auditorium

April 26, 2010 – Aluminum hydride, or Alane, is an interesting material for a wide variety of applications ranging from a hydrogen storage medium for use in automobiles to a fuel supplement in explosives, fuels, and propellants. Alane is particularly interesting as an ingredient in fuels and propellants in propulsion systems, because of its ability to substantially increase the performance of a given system. For instance, thermochemical calculations using the NASA CEA chemical equilibrium code indicate that replacement of aluminum with alane in a typical composite solid rocket propellant (Ammonium Perchlorate/HTPB/Aluminum) increases the specific impulse (Isp) by ~7-8% while also substantially reducing the adiabatic flame temperature. This type of increase in specific impulse can provide large gains in vehicle range as well as significantly decrease the cost of launching a payload into space. For these reasons, alane has been a fuel of great interest since the 1960’s. While it is an extremely attractive material it’s high cost, limited availability, and thermal stability issues have minimized its use. Thus, relatively little information is available on alane in terms of combustion and propulsion behavior. Recently, interest has been renewed in aluminum hydride, sparking a series of studies providing researchers with a rich new area of exploration.