NO ABSTRACT (KAR)
Topics: DTIC Archive, Chapman, Dean R., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
This paper presents research results dealing with power MOSFETs (metal oxide semiconductor field effect transistor) within the prognostics and health management of electronics. Experimental results are presented for the identification of the on-resistance as a precursor to failure of devices with die-attach degradation as a failure mechanism. Devices are aged under power cycling in order to trigger die-attach damage. In situ measurements of key electrical and thermal parameters are collected...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Autonomous vertical lift vehicles hold considerable potential for supporting planetary science and exploration missions. This paper discusses several technical aspects of vertical lift planetary aerial vehicles in general, and specifically addresses technical challenges and work to date examining notional vertical lift vehicles for Mars, Titan, and Venus exploration.
Topics: DTIC Archive, Young, Larry A, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
With the advent of the next generation of aerospace systems equipped with fly-by-wire controls, electromechanical actuators (EMA) are quickly becoming components critical to safety of aerospace vehicles. Being relatively new to the field, however, EMA lack the knowledge base compared to what is accumulated for the more traditional actuator types, especially when it comes to fault detection and prognosis. Scarcity of health monitoring data from fielded systems and prohibitive costs of carrying...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Prognostics is an emerging science of predicting the health condition of a system (or its components) based upon current and previous system states. A reliable predictor is very useful to a wide array of industries to predict the future states of the system such that the maintenance service could be scheduled in advance when needed. In this paper, an adaptive recurrent neural network (ARNN) is proposed for system dynamic state forecasting. The developed ARNN is constructed based on the...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
A first-of-its-kind demonstration of the use of localized, non-harmonic active flap motions, for suppressing low frequency, in-plane rotor noise, is reported in this paper. Operational feasibility is verified via testing of the full-scale AATD/Sikorsky/UTRC active flap demonstration rotor in the NFAC's 40- by 80-Foot anechoic wind tunnel. Effectiveness of using localized, non-harmonic active flap motions are compared to conventional four-per-rev harmonic flap motions, and also active flap...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
By the time this Proceedings is published, almost 2 years will have elapsed since the NASA-U.C. Berkeley Conference on Spatial Displays and Spatial Instruments held August 31- September 3, 1987, at the Asilomar Conference Center in Pacific Grove, California. The publication of the papers included in this proceedings will be a major step toward completion of a book to be based on material presented at the conference. Though the book itself will have a totally different organization, this...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, Rolls, L. S., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Topics: DTIC Archive, NELSON, WARREN H., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
We are studying how robotic follow-up can improve future planetary exploration. Robotic follow-up, which we define as augmenting human field work with subsequent robot activity, is a field exploration technique designed to increase human productivity and science return. To better understand the benefits, requirements, limitations and risks associated with this technique, we are conducting analog field tests with human and robot teams at the Haughton Crater impact structure on Devon Island,...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, MCNEILL, WALTER E., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
Power electronics are widely used in critical roles in modern day aircrafts and hence their health management is of great interest. An important part of prognostics and health management of these devices is understanding the effect of high-stress events such as lightning and how they affect their aging. In this paper we present our study and analysis of lightning injection experiments with power MOSFETs in their ON state. We show the different kind of damages that can be caused by such events...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
The N, N2 system is studied to yield rate coefficients and cross sections for molecular dissociation under conditions important for assessing nonequilibrium heating of hypersonic vehicles. First principle calculations are used to generate realistic nuclear interaction potentials, and these are used with accurate molecular dynamics to yield the fundamental data required for a rigorous treatment of nonequilibrium chemistry.
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
This article discusses several aspects of uncertainty representation and management for model-based prognostics methodologies based on our experience with Kalman Filters when applied to prognostics for electronics components. In particular it explores the implications of modeling remaining useful life prediction as a stochastic process and how it relates to uncertainty representation, management, and the role of prognostics in decision-making. A distinction between the interpretations of...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, KENYON, GEORGE C., REYNOLDS, ROBERT M., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...
Topics: DTIC Archive, White, John S, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
This paper details the development and demonstration of an autonomous aerial vehicle embodying search and find mission planning and execution strategies inspired by foraging behaviors found in biology. It begins by describing key characteristics required by an aerial explorer to support science and planetary exploration goals, and illustrates these through a hypothetical mission profile. It next outlines a conceptual bioinspired search and find autonomy architecture that implements...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, Clousing, Lawrence A., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
Flight test measurements of the performance of the UH-60 Black Hawk helicopter with both standard and advanced rotors are compared with calculations obtained using the comprehensive helicopter analysis CAMRAD II. In general, the calculated power coefficient shows good agreement with the flight test data. However, the accuracy of the calculation degrades at high gross weight for all of the configurations. The analysis shows fair to good correlation for collective and longitudinal cyclic angles...
Topics: DTIC Archive, Yeo, Hyeonsoo, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
The Active Elevon Rotor (AER) is a 12.96 ft. diameter rotor with two on-blade elevons on each blade. Each elevon is a 15% chord, 8% span, plain, trailing-edge flap actuated by a piezoceramic-based conformal actuator. Development of the rotor and support systems has been completed and is documented, especially regarding the actuation system, blades, test stand, and controls. Development of two control algorithms - classical and Model Predictive Control (MPC) is described for elevon position...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, Goett, Harry J, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Electrolytic capacitors are used in several applications ranging from power supplies on safety critical avionics equipment to power drivers for electromechanical actuators, and this makes them good candidates for prognostics and health management research. Prognostics provides a way to assess remaining useful life of components or systems based on their current state of health and their anticipated future use and operational conditions. Past experiences show that capacitors tend to degrade and...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
A new tiltrotor aeroacoustic research facility, the Tilt Rotor Aeroacoustic Model (TRAM), is being developed by NASA and the U. S. Army. The TRAM Project will enable new insights into the fundamental aeroacoustics of proprotors and tiltrotor aircraft, leading to improved acoustic prediction methodologies and noise reduction techniques. An overview of NASA's goals in understanding and reducing the technology barriers for civil tiltrotor aircraft is provided as well as a description of how TRAM...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, Resnikoff, Meyer M., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
This paper examines the relationship between outsourcing and changing environments, with particular focus on changes that lead to paradigm shifts. Three different types of outsourcing requirements are identified. Each type of outsourcing requiring different management processes.
Topics: DTIC Archive, O'Neill, John, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Recently developed forward slotted airfoils were applied to a UH-60A helicopter, and the performance has been estimated. Baseline SC1095 and SC1094 R8 airfoil characteristics were modified based on CFD calculations of an A3c slotted airfoil to incorporate aerodynamic characteristics of a high-lifting airfoil. The slotted airfoil increases maximum thrust of the UH-60A helicopter by up to 25%, but a significant penalty is observed at CT/sigma less than 0.11. This penalty results from higher drag...
Topics: DTIC Archive, Yeo, Hyeonsoo, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Topics: DTIC Archive, Hamaker, Frank M., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
The design and performance of compound helicopters utilizing lift-offset rotors are examined, in the context of short-haul, medium-size civil and military missions. The analysis tools used are the comprehensive analysis CAMRAD II and the sizing code NDARC. Following correlation of the comprehensive analysis with existing lift-offset aircraft flight test data, the rotor performance model for the sizing code was developed, and an initial estimate was made of the rotor size and key hover and...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
The total horizontal-tail load and the root bending moment increments calculated by the use of existing rational procedures are compared with experimental values obtained in pull-up push-down maneuvers on a representative propeller-driven pursuit-type airplane for six different combinations of power, indicated airspeed, and pressure altitude. The computed loads were determined for the experimental elevator motions, and for two estimated linear design motions. There is also presented a...
Topics: DTIC Archive, Sadoff, Melvin, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
The rolling moment due to sideslip in supersonic flow has been calculated for a representative group of plan forms. The analysis was based on linearized potential theory and was applied to triangular, trapezoidal, rectangular, and sweptback plan forms without dihedral. The only types of plan forms that provided positive dihedral effect throughout the range of Mach number investigated were the rectangular wing of very low aspect ratio and a trapezoidal wing of moderately low aspect ratio having...
Topics: DTIC Archive, Jones, Arthur L, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
This paper provides an updated efficiency analysis of the LightForce space debris collision avoidance scheme. LightForce aims to prevent collisions on warning by utilizing photon pressure from ground based, commercial off the shelf lasers. Past research has shown that a few ground-based systems consisting of 10 kW class lasers directed by 1.5 m telescopes with adaptive optics could lower the expected number of collisions in Low Earth Orbit (LEO) by an order of magnitude. Our simulation approach...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
An aeroacoustic wind tunnel test was conducted using a scaled isolated tiltrotor model. Acoustic data were acquired using an in-flow microphone wing traversed beneath the model to map the directivity of the near-field acoustic radiation of the rotor for a parametric variation of rotor angle-of-attack, tunnel speed, and rotor thrust. Acoustic metric data were examined to show trends of impulsive noise for the parametric variations. BVISPL maximum noise levels were found to increase with a for...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Safety of the next-generation space flight vehicles requires development of an in-flight Failure Detection and Prognostic (FD&P) system. Development of such system is challenging task that involves analysis of many hard hitting engineering problems across the board. In this paper we report progress in the development of FD&P for the re-contact fault between upper stage nozzle and the inter-stage caused by the first stage and upper stage separation failure. A high-fidelity models and...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, SYVERTSON, CLARENCE A., SAVIN, RAYMOND C., NATIONAL AERONAUTICS AND SPACE...
Diagnosis and prognosis are necessary tasks for system reconfiguration and fault-adaptive control in complex systems. Diagnosis consists of detection, isolation and identification of faults, while prognosis consists of prediction of the remaining useful life of systems. This paper presents a novel integrated framework for model-based distributed diagnosis and prognosis, where system decomposition is used to enable the diagnosis and prognosis tasks to be performed in a distributed way. We show...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, HERRERA, RAYMOND, BARNES, ROBERT H., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...
A NACA 0015 semispan wing was placed in a low-speed wind tunnel, and measurements were made of the pressure on the upper and lower surface of the wing and of the velocity across the vortex trailing downstream from the tip of the wing. Pressure data were obtained for both 2D and 3D configurations. These data feature a detailed comparison between wing tips with square and round lateral edges. A two-component laser velocimeter was used to measure velocity profiles across the vortex at numerous...
Topics: DTIC Archive, McAlister, K W, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Topics: DTIC Archive, ALLEN, H. J., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Topics: DTIC Archive, SMITH, DONALD W., REED, VERLIN D., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION...
Topics: DTIC Archive, Vincenti, Walter G, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
This Technical Publication presents results that attempt to establish the fundamental relationships between rotorcraft size and handling qualities in the critical hover and low-speed flight regime. This research was conducted through a series of piloted handling qualities experiments on the NASA Ames Vertical Motion Simulator (VMS) and supported by other simulation analyses. Attitude Command-Attitude Hold (ACAH) and Translational Rate Command (TRC) control response types are systematically...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
The Rotorcraft Dynamics Division, Aeroflightdynamics Directorate, U. S. Army Aviation Research and Technology Activity (AVSCOM) has developed the General Rotorcraft Aeromechanical Stability Program (GRASP) to calculate aeroelastic stability for rotorcraft in hovering flight, vertical flight, and ground contact conditions. In this report, GRASP is described in terms of its capabilities and the philosophy behind its modeling. The equations of motion that govern the physical system are described,...
Topics: DTIC Archive, Hodges, Dewey H, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
Topics: DTIC Archive, NEICE, STANFORD E., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
Issues in the description of places are discussed in the context of a logical geospatial theory. This theory lies at the core of the system GeoLogica, which deduces answers to geographical questions based on knowledge provided by multiple agents. Many questions cannot be answered from information in a single geographical source; often the answer must be deduced from information provided by several sources. It may not be obvious which sources to consult. Because multiple sources seldom agree on...
Topics: DTIC Archive, Waldinger, Richard, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
Resource envelopes provide the tightest exact bounds on the resource consumption and production caused by all possible executions of a temporally flexible plan. We present a new class of algorithms that computes an envelope in O(Maxflow(n, m, U)) where n, m and U measure the size of the flexible plan. This is an O(n) improvement on the best complexity bound for an envelope algorithm known so far and makes envelopes more amenable to practical use in scheduling. The reduction in complexity...
Topics: DTIC Archive, Muscettola, Nicola, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
NASA Ames Research Center's Sustainability Base is a new 50,000 sq. ft. LEED Platinum office building. Plug loads are expected to account for a significant portion of the overall energy consumption. This is because building design choices have resulted in greatly reduced energy demand from Heating, Ventilation, and Air Conditioning (HVAC) and lighting systems, which are major contributors to energy consumption in traditional buildings. In anticipation of the importance of plug loads in...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
The lungs of rats exposed to OF2 were examined by light and electron microscopy. The exposures were for 30 to 60 minutes to an average of 4.5 ppm OF2, the minimal lethal dose. Animals were sacrificed after 30 (group 1) and 60 minutes (group 2) exposure and 1 (group 3) and 2 (group 4) hours following 60 minutes exposure. Mild gross changes were observed in groups 3 and 4, but no light microscopic lesions were found. Alterations were noted in all four groups using electron microscopy. These were...
Topics: DTIC Archive, Harrison, Gladys, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES...
The natural world is a rich source of problem solving approaches. This paper discusses the feasibility and technical challenges underlying mimicking, or analogously adapting, biological behavioral strategies to mission/flight planning for aerial vehicles engaged in planetary exploration. Two candidate concepts based on natural resource utilization and searching behaviors are adapted to technological applications. Prototypes and test missions addressing the difficulties of implementation and...
Topics: DTIC Archive, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER,...
Topics: DTIC Archive, Huntsberger, Ralph F, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA...
