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Articles 1 - 30 of 59
Full-Text Articles in Entire DC Network
Trajectory Model Validation Using Newly Developed Altitude-Controlled Balloons During The International Consortium For Atmospheric Research On Transport And Transformations 2004 Campaign, Emily E. Riddle, Paul B. Voss, Andreas Stohl, Daniel Holcomb, Darren Maczka, K. Washburn, Robert W. Talbot
Trajectory Model Validation Using Newly Developed Altitude-Controlled Balloons During The International Consortium For Atmospheric Research On Transport And Transformations 2004 Campaign, Emily E. Riddle, Paul B. Voss, Andreas Stohl, Daniel Holcomb, Darren Maczka, K. Washburn, Robert W. Talbot
Engineering: Faculty Publications
During the summer of 2004, five altitude-controlled tracking balloons were flown as part of the International Consortium for Atmospheric Research on Transport and Transformations (ICARTT) campaign. These Controlled Meteorological (CMET) balloons, newly developed at the University of Massachusetts, are notable for their light weight (∼1 kg mass), efficient altitude control, case of launch, long-duration flight capability, and ability to perform repeated quasi-Lagrangian soundings. The balloons were embedded in urban plumes from New York and Boston which they tracked over New England, eastern Canada, and the Atlantic Ocean while maintaining a nearly constant altitude. The flights ranged from 10 to 111 …
Robust Control Techniques Enabling Duty Cycle Experiments Utilizing A 6-Dof Crewstation Motion Base, A Full Scale Combat Hybrid Electric Power System, And Long Distance Internet Communications, Marc Compere, Jarrett Goodell, Miguel Simon, Wilford Smith, Mark Brudnak
Robust Control Techniques Enabling Duty Cycle Experiments Utilizing A 6-Dof Crewstation Motion Base, A Full Scale Combat Hybrid Electric Power System, And Long Distance Internet Communications, Marc Compere, Jarrett Goodell, Miguel Simon, Wilford Smith, Mark Brudnak
Publications
The RemoteLink effort supports the U.S. Army's objective for developing and fielding next generation hybrid-electric combat vehicles. It is a distributed soldierin- the-Ioop and hardware-in-the-Ioop environment with a 6-DOF motion base for operator realism, a full-scale combat hybrid electric power system, and an operational context provided by OneSAF. The driver/gunner crewstations rest on one of two 6-DOF motion bases at the U.S. Army TARDEC Simulation Laboratory (TSL). The hybrid power system is located 2,450 miles away at the TARDEC Power and Energy System Integration Laboratory (P&E SIL). The primary technical challenge in the RemoteLink is to operate both laboratories together …
Integrated Guidance And Control Of Missiles With Θ-D Method, Ming Xin, S. N. Balakrishnan, Ernest J. Ohlmeyer
Integrated Guidance And Control Of Missiles With Θ-D Method, Ming Xin, S. N. Balakrishnan, Ernest J. Ohlmeyer
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A new suboptimal control method is proposed in this study to effectively design an integrated guidance and control system for missiles. Optimal formulations allow designers to bring together concerns about guidance law performance and autopilot responses under one unified framework. They lead to a natural integration of these different functions. by modifying the appropriate cost functions, different responses, control saturations (autopilot related), miss distance (guidance related), etc., which are of primary concern to a missile system designer, can be easily studied. A new suboptimal control method, called the θ-D method, is employed to obtain an approximate closed-form solution to this …
Capillary-Driven Flows Along Rounded Interior Corners, Yongkang Chen, Mark M. Weislogel, Cory L. Nardin
Capillary-Driven Flows Along Rounded Interior Corners, Yongkang Chen, Mark M. Weislogel, Cory L. Nardin
Mechanical and Materials Engineering Faculty Publications and Presentations
The problem of low-gravity isothermal capillary flow along interior corners that are rounded is revisited analytically in this work. By careful selection of geometric length scales and through the introduction of a new geometric scaling parameter Tc, the Navier–Stokes equation is reduced to a convenient∼O(1) form for both analytic and numeric solutions for all values of corner half-angle α and corner roundedness ratio λ for perfectly wetting fluids. The scaling and analysis of the problem captures much of the intricate geometric dependence of the viscous resistance and significantly reduces the reliance on numerical data compared with several previous solution methods …
Flightlines, Vol. 14, No. 1, Jeffrey A. Johnson
Flightlines, Vol. 14, No. 1, Jeffrey A. Johnson
Flightlines Newsletter
No abstract provided.
Error Allocation In Complex Systems Design, Robert A. Mcdonald
Error Allocation In Complex Systems Design, Robert A. Mcdonald
Aerospace Engineering
A fidelity trade environment was conceived, formulated, developed, and demonstrated. This development relied on the advancement of enabling techniques including error propagation, metamodeling, and information management. These techniques were integrated with an existing commercial systems design framework and an intuitive graphical interface to create a fidelity trade environment. A sensitivity approach to the propagation of error through complex systems was developed. This approach relied on the system sensitivity matrix to model the behavior of a complex system as a whole. In verification tests, the sensitivity approach provided approximate results substantially similar to a Monte Carlo approach that was many orders …
Grain Growth Behavior At Absolute Zero During Nanocrystalline Metal Indentation, F. Sansoz, V. Dupont
Grain Growth Behavior At Absolute Zero During Nanocrystalline Metal Indentation, F. Sansoz, V. Dupont
Aerospace Engineering - Daytona Beach
The authors show using atomistic simulations that stress-driven grain growth can be obtained in the athermal limit during nanocrystalline aluminum indentation. They find that the grain growth results from rotation of nanograins and propagation of shear bands. Together, these mechanisms are shown to lead to the unstable migration of grain boundaries via process of coupled motion. An analytical model is used to explain this behavior based on the atomic-level shear stress acting on the interfaces during the shear band propagation. This study sheds light on the atomic mechanism at play during the abnormal grain coarsening observed at low temperature in …
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Of High Solids Loading Ceramic Slurries, Part Ii: Extrusion Process Control, Michael S. Mason, Tieshu Huang, Robert G. Landers, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Part I of this paper provided a detailed description of a novel fabrication machine for high solids loading ceramic slurry extrusion processes and presented an empirical model of the ceramic extrusion process, viewing ram velocity as the input and extrusion force as the output. A constant extrusion force is desirable as it correlates with a constant material deposition rate and, thus, good part quality. The experimental results used to construct the model demonstrated that a constant ram velocity will not necessarily produce a constant extrusion force. In some instances the extrusion force increased until ram motor skipping occurred, and process …
Crop Production For Advanced Life Support Systems, R M. Wheeler, J C. Sager
Crop Production For Advanced Life Support Systems, R M. Wheeler, J C. Sager
Technical Reports
The use of plants for bioregenerative life support for space missions was first studied by the US Air Force in the 1950s and 1960s. Extensive testing was also conducted from the 1960s through the 1980s by Russian researchers located at the Institute of Biophysics in Krasnoyarsk, Siberia, and the Institute for Biomedical Problems in Moscow. NASA initiated bioregenerative research in the 1960s (e.g., Hydrogenomonas) but this research did not include testing with plants until about 1980, with the start of the Controlled Ecological Life Support System (CELSS) Program. The NASA CELSS research was carried out at universities, private corporations, and …
Innovative Schematic Concept Analysis For A Space Suit Portable Life Support Subsystem, M. Schuller, R. Kobrick, T. Lalk, L. Wiseman, F. Little, Et Al.
Innovative Schematic Concept Analysis For A Space Suit Portable Life Support Subsystem, M. Schuller, R. Kobrick, T. Lalk, L. Wiseman, F. Little, Et Al.
Publications
Conceptual designs for a space suit Personal Life Support Subsystem (PLSS) were developed and assessed to determine if upgrading the system using new, emerging, or projected technologies to fulfill basic functions would result in mass, volume, or performance improvements. Technologies were identified to satisfy each of the functions of the PLSS in three environments (zero-g, Lunar, and Martian) and in three time frames (2006, 2010, and 2020). The viability of candidate technologies was evaluated using evaluation criteria such as safety, technology readiness, and reliability. System concepts (schematics) were developed for combinations of time frame and environment by assigning specific technologies …
Reweighting At-Sat To Mitigate Group Score Differences, Andrew R. Dattel, Raymond E. King
Reweighting At-Sat To Mitigate Group Score Differences, Andrew R. Dattel, Raymond E. King
Publications
The Air Traffic Selection and Training (AT-SAT) test battery is the selection tool for applicants for Air Traffic Control Specialist (ATCS) positions within the Federal Aviation Administration (FAA) who have not previously been employed as an air traffic controller. AT-SAT is an aptitude test developed to predict the likelihood of successfully learning ATCS skills. Before operational use, however, concerns were raised about the low passing rate of incumbent (who are fully trained and certified) ATCS personnel (who participated in the initial research) and score differences between groups, which could result in adverse impact (possible unfair discrimination). To address these concerns, …
Attribute-Level Neighbor Hierarchy Construction Using Evolved Pattern-Based Knowledge Induction, Thanit Puthpongsiriporn, J. David Porter, Bopaya Bidanda, Ming En Wang, Richard E. Billo
Attribute-Level Neighbor Hierarchy Construction Using Evolved Pattern-Based Knowledge Induction, Thanit Puthpongsiriporn, J. David Porter, Bopaya Bidanda, Ming En Wang, Richard E. Billo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Neighbor knowledge construction is the foundation for the development of cooperative query answering systems capable of searching for close match or approximate answers when exact match answers are not available. This paper presents a technique for developing neighbor hierarchies at the attribute level. The proposed technique is called the evolved Pattern-based Knowledge Induction (ePKI) technique and allows construction of neighbor hierarchies for nonunique attributes based upon confidences, popularities, and clustering correlations of inferential relationships among attribute values. The technique is applicable for both categorical and numerical (discrete and continuous) attribute values. Attribute value neighbor hierarchies generated by the ePKI technique …
Investigation Of Particle-In-Cell Acceleration Techniques For Plasma Simulations, David D. Marshall, Douglas B. Vangilder
Investigation Of Particle-In-Cell Acceleration Techniques For Plasma Simulations, David D. Marshall, Douglas B. Vangilder
Aerospace Engineering
COLISEUM is an application framework that integrates plasma propagation schemes and arbitrary 3D surface geometries. Using Particle-in-Cell (PIC) schemes to model the plasma propagation high fidelity modeling of the plasma and its interactions with the surfaces is possible. In order to improve the computational performance of the Particle-in-Cell scheme with Direct Simulation Monte Carlo collision modeling (PIC-DSMC) within COLISEUM, AQUILA, acceleration techniques have been developed that significantly decrease the amount of CPU time needed to obtain a steady-state solution. These techniques have been demonstrated to decrease the CPU time from 3 to 24 times with little appreciable differences in the …
Experiences In Accurately Predicting Time-Dependent Flows, Russell M. Cummings, Scott A. Morton, David R. Mcdaniel
Experiences In Accurately Predicting Time-Dependent Flows, Russell M. Cummings, Scott A. Morton, David R. Mcdaniel
Aerospace Engineering
As computational fluid dynamics matures, researchers attempt to perform numerical simulations on increasingly complex aerodynamic flows. One type of flow that has become feasible to simulate is massively separated flow fields, which exhibit high levels of flow unsteadiness. While traditional computational fluid dynamic approaches may be able to simulate these flows, it is not obvious what restrictions should be followed in order to insure that the numerical simulations are accurate and trustworthy. Our research group has considerable experience in computing massively separated flow fields about various aircraft configurations, which has led us to examine the factors necessary for making high-quality …
Kalman Filtering With Inequality Constraints For Turbofan Engine Health Estimation, Daniel J. Simon, Donald L. Simon
Kalman Filtering With Inequality Constraints For Turbofan Engine Health Estimation, Daniel J. Simon, Donald L. Simon
Electrical and Computer Engineering Faculty Publications
Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state-variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. Thus, two analytical methods to incorporate state-variable inequality constraints into the Kalman filter are now derived. The first method is a general technique that uses hard constraints to enforce inequalities on the state-variable estimates. The resultant filter is a combination …
Flightlines, Vol. 13, No. 2, Jeffrey A. Johnson
Flightlines, Vol. 13, No. 2, Jeffrey A. Johnson
Flightlines Newsletter
No abstract provided.
Contingency Planning And An Air Force Space Command Information System, Kaylin Freedman, Michael R. Grimaila
Contingency Planning And An Air Force Space Command Information System, Kaylin Freedman, Michael R. Grimaila
Faculty Publications
No abstract provided.
Managing The Integration Of Space And Information Operations, Daniel F. Gottrich, Michael R. Grimaila
Managing The Integration Of Space And Information Operations, Daniel F. Gottrich, Michael R. Grimaila
Faculty Publications
No abstract provided.
A Game Theory Approach To Constrained Minimax State Estimation, Daniel J. Simon
A Game Theory Approach To Constrained Minimax State Estimation, Daniel J. Simon
Electrical and Computer Engineering Faculty Publications
This paper presents a game theory approach to the constrained state estimation of linear discrete time dynamic systems. In the application of state estimators, there is often known model or signal information that is either ignored or dealt with heuristically. For example, constraints on the state values (which may be based on physical considerations) are often neglected because they do not easily fit into the structure of the state estimator. This paper develops a method for incorporating state equality constraints into a minimax state estimator. The algorithm is demonstrated on a simple vehicle tracking simulation.
Experimental Evaluation Of A High Fineness Ratio Body With Drag Brakes, Corey J. Florendo, Thomas R. Yechout, Stefan G. Siegel, Russell M. Cummings, Joseph Kealos
Experimental Evaluation Of A High Fineness Ratio Body With Drag Brakes, Corey J. Florendo, Thomas R. Yechout, Stefan G. Siegel, Russell M. Cummings, Joseph Kealos
Aerospace Engineering
No abstract provided.
Experimental Evaluation Of A High Fineness Ratio Body With Drag Brakes, Corey J. Florendo, Thomas R. Yechout, Stefan Siegel, Russell M. Cummings, Joseph Kealos
Experimental Evaluation Of A High Fineness Ratio Body With Drag Brakes, Corey J. Florendo, Thomas R. Yechout, Stefan Siegel, Russell M. Cummings, Joseph Kealos
Aerospace Engineering
The Advanced Remote Ground Unattended Sensor uses drag brakes to control its terminal velocity during flight. An experimental evaluation of the geometry was performed at Mach numbers between 0.20 and 0.50 with a 61.5% scale model in the U.S. Air Force Academy Subsonic Wind Tunnel. Configurations tested include baseline drag brakes fully deployed, an array of perforated drag brake designs, as well as various other related drag brake design features. Improvements to the baseline design are discussed and an improved configuration is presented. Limited unsteady computations were performed for selected cases using detached-eddy simulation to understand various experimental results. The …
Numerical Evaluation Of The Flowfield For A High Fineness Ratio Body With Drag Brakes, Russell M. Cummings, James A. Divine, Thomas R. Yechout, David C. Wetlesen, Joseph J. Kealos
Numerical Evaluation Of The Flowfield For A High Fineness Ratio Body With Drag Brakes, Russell M. Cummings, James A. Divine, Thomas R. Yechout, David C. Wetlesen, Joseph J. Kealos
Aerospace Engineering
The Advanced Remote Ground Unattended Sensor (ARGUS) utilizes drag brakes to control its terminal velocity during flight. Computational fluid dynamics predictions were performed at Mach numbers between 0.20 and 0.95 with a full scale model of the ARGUS configuration at conditions to match wind tunnel testing that has been performed at the USAFA Subsonic Wind Tunnel. Configurations consist of brakes fully deployed for a nominal brake fin and a perforated brake fin. Steady-stated computations were performed using the Spalart-Allmaras turbulence model at angles of attack between 0 degrees to 20 degrees at roll angles of 0 degrees and 45 degrees. …
The Influence Of Viscosity And Surface Curvature On The Pressure Distribution Of A Stream Thrust Probe, Renee Pasman, Russell M. Cummings
The Influence Of Viscosity And Surface Curvature On The Pressure Distribution Of A Stream Thrust Probe, Renee Pasman, Russell M. Cummings
Aerospace Engineering
Determining the local stream thrust (a vector quantity) from a measured pitot pressure (a scalar quantity) requires either knowledge of the flow direction, or a probe shape that compensates for flow direction. This compensation would ideally make the measured pressure directly proportional to the component of momentum along the probe axis. The flow angle sensitivity required to resolve this component of momentum was determined theoretically previously. A proposed probe nose shape was analyzed using CFD and found to produce flow angle sensitivity close to the required sensitivity. The proposed nose shape was also tested in a wind tunnel at Mach …
United States Air Force Posture Statement 2006, U.S. Air Force
United States Air Force Posture Statement 2006, U.S. Air Force
U.S. Air Force Research
Over a century ago, America crossed the threshold of powered flight and gave wings to the world. Soon military leaders realized the implications of this development, and warfare was changed forever. America was fortunate to have "Great Captains" with the vision to imagine the possibilities of air and space power - Airmen like Billy Mitchell, Frank Andrews, Hap Arnold, Ira Eaker, Jimmy Doolittle, Bennie Schriever. They have given us a proud heritage of courage, excellence and innovation. In so doing, they also give us a sense of perspective and a way to understand the Air Force's future.
Basic Materials Research Programs At The U.S. Air Force Office Of Scientific Research, Herbert C. Carlson, K. C. Goretta
Basic Materials Research Programs At The U.S. Air Force Office Of Scientific Research, Herbert C. Carlson, K. C. Goretta
U.S. Air Force Research
The Air Force Office of Scientific Research (AFOSR) annually sponsors approximately 5000 research scientists at 1000 universities and laboratories, generating about 10,000 Ph.D. graduates per decade, all expected to publish their basic research findings in peer-reviewed journals. After a brief introduction of the nature of AFOSR’s support to basic research in the U.S. and international scientific communities, work it supports at the frontiers of materials science is highlighted. One focused research theme that drives our investment is the MEANS program. It begins with the end in mind; materials are designed with practicable manufacture as an explicit initial goal. AFOSR’s broad …
Field-Scale Demonstration Of Induced Biogeochemical Reductive Dechlorination At Dover Air Force Base, Dover, Delaware, Lonnie G. Kennedy, Jess W. Everett, Erica Becvar, Donald Defeo
Field-Scale Demonstration Of Induced Biogeochemical Reductive Dechlorination At Dover Air Force Base, Dover, Delaware, Lonnie G. Kennedy, Jess W. Everett, Erica Becvar, Donald Defeo
U.S. Air Force Research
Biogeochemical reductive dechlorination (BiRD) is a new remediation approach for chlorinated aliphatic hydrocarbons (CAHs). The approach stimulates common sulfate-reducing soil bacteria, facilitating the geochemical conversion of native iron minerals into iron sulfides. Iron sulfides have the ability to chemically reduce many common CAH compounds including PCE, TCE, DCE, similar to zero valent iron (Fe0). Results of a field test at Dover Air Force Base, Dover, Delaware, are given in this paper. BiRD was stimulated by direct injection of Epson salt (MgSO4·7H2O) and sodium (L) lactate (NaC3H5O3) in five …
Critical Hypersonic Aerothermodynamic Phenomena, John J. Bertin, Russell M. Cummings
Critical Hypersonic Aerothermodynamic Phenomena, John J. Bertin, Russell M. Cummings
Aerospace Engineering
The challenges in understanding hypersonic flight are discussed and critical hypersonic aerothermodynamics issues are reviewed. The ability of current analytical methods, numerical methods, ground testing capabilities, and flight testing approaches to predict hypersonic flow are evaluated. The areas where aerothermodynamic shortcomings restrict our ability to design and analyze hypersonic vehicles are discussed, and prospects for future capabilities are reviewed. Considerable work still needs to be done before our understanding of hypersonic flow will allow for the accurate prediction of vehicle flight characteristics throughout the flight envelope from launch to orbital insertion.
Continuing Evolution Of Aerodynamic Concept Development Using Collaborative Numerical And Experimental Evaluations, Russell M. Cummings, Scott A. Morton
Continuing Evolution Of Aerodynamic Concept Development Using Collaborative Numerical And Experimental Evaluations, Russell M. Cummings, Scott A. Morton
Aerospace Engineering
Traditionally, computational predictions and experimental evaluations of aerodynamic concepts have been conducted separately, with little collaboration other than post priori comparisons of results. This has led to distrust and even antagonism between the computational and the experimental communities. These difficulties probably began when early computational fluid dynamic practitioners boasted that wind tunnels would become secondary in aerodynamic concept development within a few short years, a prediction that has not come true. On the contrary, it is believed that a great deal of synergy can be cultivated when computational and experimental evaluations are conducted in an integrative fashion. A variety of …
A Sustainable, Systematic Process For Continuous Program Improvement, Nikos J. Mourtos
A Sustainable, Systematic Process For Continuous Program Improvement, Nikos J. Mourtos
Faculty Publications
The USA Accreditation Board for Engineering and Technology (ABET) adopted recently a new set of criteria for evaluating engineering programmes. One of these (criterion 3) refers to programme outcomes and assessment. In this article, the author describes the design and implementation of a sustainable, systematic process for defining and assessing programme outcomes. This process involves analysing each outcome into elements, defining a set of attributes for each element, selecting outcome indicators and performance targets, and developing special rubrics for an accurate assessment of student skills. The author also describes a systematic way of addressing specific programme outcomes through course and …
Nonlinear Model Predictive Control Technique For Unmanned Air Vehicles, Nathan Slegers, Jason Kyle, Mark Costello
Nonlinear Model Predictive Control Technique For Unmanned Air Vehicles, Nathan Slegers, Jason Kyle, Mark Costello
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
A nonlinear model predictive control strategy is developed and subsequently specialized to autonomous aircraft that can be adequately modeled with a rigid 6-degrees-of-freedom representation. Whereas the general air vehicle dynamic equations are nonlinear and nonaffine in control, a closed-form solution for the optimal control input is enabled by expanding both the output and control in a truncated Taylor series. The closed-form solution for control is relatively simple to calculate and well suited to the real time embedded computing environment. An interesting feature of this control law is that the number of Taylor series expansion terms can be used to indirectly …