Recursos de colección

NASA Technical Reports Server (NTRS) (683.741 recursos)

The NTRS is a valuable resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994. NTRS provides access to approximately 500K aerospace related citations, 90K full-text online documents, and 111K images and videos. NTRS numbers continues to grow over time as new scientific and technical information (STI) is created or funded by NASA. The type of information found in NTRS include: conference papers, images, journal articles, photos, meeting papers, movies, patents, research reports, and technical videos.

Mostrando recursos 1 - 20 de 319.171

  1. Spatial and Temporal Variability of Carbon Dioxide Using Structure Functions in Urban Areas: Insights for Future Active Remote CO2 Sensors

    DiGangi, Joshua P.; Browell, Edward V.; Yang, Melissa; Choi, Yonghoon; Kooi, Susan A.
    High resolution in-situ CO2 measurements were recorded onboard the NASA P-3B during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) Field Campaigns during July 2011 over Washington DC/Baltimore, MD; January-February 2013 over the San Joaquin Valley, CA; September 2013 over Houston, TX; and July-August 2014 over Denver, CO. Each of these campaigns have approximately two hundred vertical soundings of CO2 within the lower troposphere (surface to about 5 kilometers) at 6-8 different sites in each of the urban areas. In this study, we used structure function analysis, which is a useful...

  2. Inflatable Reentry Vehicles and Instrumentation Needs

    Dillman, Robert
    Charts for discussion of LaRC work on inflatable reentry vehicles, and sensors sought for future flights.

  3. Recent Developments in FUN3D: Entropy Stable DG-FEM

    Parsani, Matteo; Nielsen, Eric J.; Carpenter, Mark H.
    No abstract available

  4. Synthesis and Modification of Holey Graphene for Energy Storage

    Kim, Jae-Woo; Lin, Yi; Connell, John W.
    No abstract available

  5. Analysis of Advanced Thermoelectric Materials and Their Functional Limits

    Kim, Hyun Jung
    No abstract available

  6. State of the Carbon Cycle - Consequences of Rising Atmospheric CO2

    Yu, Rita M. S.; Shadwick, Elizabeth H.; Cooley, Sarah R.; Potter, Christopher S.; Sutton, Adrienne J.; Johnson, Zackary I.; Lohrenz, Steven E.; French, Nancy H. F.; Moore, David J.; Butman, David E.; Alin, Simone R.; Brown, Molly; Keppel-Aleks; Ocko, Ilissa
    The rise of atmospheric CO2, largely attributable to human activity through fossil fuel emissions and land-use change, has been dampened by carbon uptake by the ocean and terrestrial biosphere. We outline the consequences of this carbon uptake as direct and indirect effects on terrestrial and oceanic systems and processes for different regions of North America and the globe. We assess the capacity of these systems to continue to act as carbon sinks. Rising CO2 has decreased seawater pH; this process of ocean acidification has impacted some marine species and altered fundamental ecosystem processes with further effects likely. In terrestrial ecosystems,...

  7. Hot-Fire Test Results of an Oxygen/RP-2 Multi-Element Oxidizer-Rich Staged-Combustion Integrated Test Article

    Casiano, M. J.; Garcia, C. P.; Hulka, J. R.; Parton, J. A.; Protz, C. S.
    As part of the Combustion Stability Tool Development project funded by the Air Force Space and Missile Systems Center, the NASA Marshall Space Flight Center was contracted to assemble and hot-fire test a multi-element integrated test article demonstrating combustion characteristics of an oxygen/hydrocarbon propellant oxidizer-rich staged-combustion engine thrust chamber. Such a test article simulates flow through the main injectors of oxygen/kerosene oxidizer-rich staged combustion engines such as the Russian RD-180 or NK-33 engines, or future U.S.-built engine systems such as the Aerojet-Rocketdyne AR-1 engine or the Hydrocarbon Boost program demonstration engine. For the thrust chamber assembly of the test article,...

  8. Optimal Growth in Hypersonic Boundary Layers

    Choudhari, Meelan M.; Chang, Chau-Lyan; Li, Fei; Paredes, Pedro
    The linear form of the parabolized linear stability equations is used in a variational approach to extend the previous body of results for the optimal, nonmodal disturbance growth in boundary-layer flows. This paper investigates the optimal growth characteristics in the hypersonic Mach number regime without any high-enthalpy effects. The influence of wall cooling is studied, with particular emphasis on the role of the initial disturbance location and the value of the spanwise wave number that leads to the maximum energy growth up to a specified location. Unlike previous predictions that used a basic state obtained from a self-similar solution to...

  9. Recent Advancements in the Infrared Flow Visualization System for the NASA Ames Unitary Plan Wind Tunnels

    Garbeff, Theodore J., II; Baerny, Jennifer K.
    The following details recent efforts undertaken at the NASA Ames Unitary Plan wind tunnels to design and deploy an advanced, production-level infrared (IR) flow visualization data system. Highly sensitive IR cameras, coupled with in-line image processing, have enabled the visualization of wind tunnel model surface flow features as they develop in real-time. Boundary layer transition, shock impingement, junction flow, vortex dynamics, and buffet are routinely observed in both transonic and supersonic flow regimes all without the need of dedicated ramps in test section total temperature. Successful measurements have been performed on wing-body sting mounted test articles, semi-span floor mounted aircraft...

  10. NDARC NASA Design and Analysis of Rotorcraft - Input, Appendix 4

    Johnson, Wayne
    The NDARC code performs design and analysis tasks. The design task involves sizing the rotorcraft to satisfy specified design conditions and missions. The analysis tasks can include off-design mission performance analysis, flight performance calculation for point operating conditions, and generation of subsystem or component performance maps. The principal tasks (sizing, mission analysis, flight performance analysis) are shown in the figure as boxes with heavy borders. Heavy arrows show control of subordinate tasks. The aircraft description consists of all the information, input and derived, that denes the aircraft. The aircraft consists of a set of components, including fuselage, rotors, wings, tails,...

  11. Aeroservoelastic Modeling of Body Freedom Flutter for Control System Design

    Ouellette, Jeffrey
    One of the most severe forms of coupling between aeroelasticity and flight dynamics is an instability called freedom flutter. The existing tools often assume relatively weak coupling, and are therefore unable to accurately model body freedom flutter. Because the existing tools were developed from traditional flutter analysis models, inconsistencies in the final models are not compatible with control system design tools. To resolve these issues, a number of small, but significant changes have been made to the existing approaches. A frequency domain transformation is used with the unsteady aerodynamics to ensure a more physically consistent stability axis rational function approximation...

  12. New Flutter Analysis Technique for Time-Domain Computational Aeroelasticity

    Pak, Chan-Gi; Lung, Shun-Fat
    A new time-domain approach for computing flutter speed is presented. Based on the time-history result of aeroelastic simulation, the unknown unsteady aerodynamics model is estimated using a system identification technique. The full aeroelastic model is generated via coupling the estimated unsteady aerodynamic model with the known linear structure model. The critical dynamic pressure is computed and used in the subsequent simulation until the convergence of the critical dynamic pressure is achieved. The proposed method is applied to a benchmark cantilevered rectangular wing.

  13. Optimal Control Allocation with Load Sensor Feedback for Active Load Suppression, Experiment Development

    Miller, Christopher J.; Goodrick, Dan
    The problem of control command and maneuver induced structural loads is an important aspect of any control system design. The aircraft structure and the control architecture must be designed to achieve desired piloted control responses while limiting the imparted structural loads. The classical approach is to utilize high structural margins, restrict control surface commands to a limited set of analyzed combinations, and train pilots to follow procedural maneuvering limitations. With recent advances in structural sensing and the continued desire to improve safety and vehicle fuel efficiency, it is both possible and desirable to develop control architectures that enable lighter vehicle...

  14. Optimal Control Allocation with Load Sensor Feedback for Active Load Suppression, Flight-Test Performance

    Goodrick, Dan; Miller, Christopher J.
    The problem of control command and maneuver induced structural loads is an important aspect of any control system design. The aircraft structure and the control architecture must be designed to achieve desired piloted control responses while limiting the imparted structural loads. The classical approach is to utilize high structural margins, restrict control surface commands to a limited set of analyzed combinations, and train pilots to follow procedural maneuvering limitations. With recent advances in structural sensing and the continued desire to improve safety and vehicle fuel efficiency, it is both possible and desirable to develop control architectures that enable lighter vehicle...

  15. Methods of Constructing a Blended Performance Function Suitable for Formation Flight

    Ryan, John J.
    This paper presents two methods for constructing an approximate performance function of a desired parameter using correlated parameters. The methods are useful when real-time measurements of a desired performance function are not available to applications such as extremum-seeking control systems. The first method approximates an a priori measured or estimated desired performance function by combining real-time measurements of readily available correlated parameters. The parameters are combined using a weighting vector determined from a minimum-squares optimization to form a blended performance function. The blended performance function better matches the desired performance function mini- mum than single-measurement performance functions. The second method...

  16. Determining the Products of Inertia for Small Scale UAVs

    Lorenzetti, Joseph S.; Clarke, Robert; Banuelos, Leonel C.; Bowers, Albion H.; Murillo, Oscar J.
    Moments of inertia and products of inertia often need to be determined for aircraft. As complex bodies, their mass properties need to be determined experimentally for best accuracy. While several moment of inertia experimental techniques have been developed, there are few to determine the products of inertia. Products of inertia can be easily determined mathematically if the angle between the aircraft x body axis and principal x axis is known. This method finds the principal inclination angle by mathematically correlating the measured moments of inertia about a range of axes of the aircraft. This correlation uses a least squares error...

  17. Aeroservoelastic Modeling of Body Freedom Flutter for Control System Design

    Ouellette, Jeffrey
    No abstract available

  18. Hybrid-Electric Integrated Systems Testbed (HEIST)

    Papathakis, Kurt
    No abstract available

  19. Dynamic Leading-Edge Stagnation Point Determination Utilizing an Array of Hot-Film Sensors with Unknown Calibration

    Ellsworth, Joel C.
    This presentation presents the results of an algorithm to find the leading edge stagnation point using a sensor array with unknown calibration.

  20. A Tool for the Automated Collection of Space Utilization Data: Three Dimensional Space Utilization Monitor

    Ngo, Phong H.; Morency, Richard; Fink, Patrick; Vos, Gordon A.; Perez, Lance C.; Simon, Cory; Williams, Robert E.
    Space Human Factors and Habitability (SHFH) Element within the Human Research Program (HRP) and the Behavioral Health and Performance (BHP) Element are conducting research regarding Net Habitable Volume (NHV), the internal volume within a spacecraft or habitat that is available to crew for required activities, as well as layout and accommodations within the volume. NASA needs methods to unobtrusively collect NHV data without impacting crew time. Data required includes metrics such as location and orientation of crew, volume used to complete tasks, internal translation paths, flow of work, and task completion times. In less constrained environments methods exist yet many...

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