SEARCH · Search NASA

Results for “experimental implementation”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5

All sources NASA NTRS DOE OSTI

NASA NTRS1996

Simulations of Active Vortex Generators

We are interested in the study, via numerical simulations, of active vortex generators. Vortex generators may be used to modify the inner part of the boundary layer or to control separation thus enhancing the performance and maneuverability of aerodynamic configurations. We consider generators that consist of a surface cavity elongated in the streamwise direction and partially covered with a moving lid that at rest lies flush with the boundary. Streamwise voracity is generated and ejected due to the oscillatory motion of the lid. The present simulations c Implement relevant experimental investigations of active vortex generators that have been conducted at NASA Ames Research Center and Stanford University. Jacobson and Reynolds used a piezoelectric device in water, allowing for small amplitude high frequency oscillations. They placed the lid asymmetrically on the cavity and observed a strong outward velocity at the small gap of the cavity. Saddoughi used a larger mechanically driven device in air to investigate this flow and observed a jet emerging from the wide gap of the configuration, contrary to the findings of Jacobson and Reynolds. More recently, Lachowiez and Wlezien are investigating the flow generated by an electro-mechanically driven lid to be used for assertion control in aerodynamic applications. We are simulating the flows generated by these devices and we are conducting a parametric study that would help us elucidate the physical mechanisms present in the flow. Conventional computational schemes encounter difficulties when simulating flows around complex configurations undergoing arbitrary motions. Here we present a formulation that achieves this task on a purely Lagrangian frame by extending the formulation presented by Koumoutsakos, Leonard and Pepin. The viscous effects are taken into account by modifying the strength of the particles, whereas fast multipole schemes employing hundreds of thousands ol'particle's allow for high resolution simulations. We shall present simulation results of an oscillating plate at various Reynolds numbers and Strouhal frequencies. Estimates of the forces needed to drive the devices will also be presented.

Mansour, N. N.↗

NASA NTRS2003

Acquisition of Earth Science Remote Sensing Observations from Commercial Sources: Lessons Learned from the Space Imaging IKONOS Example

In an effort to more full explore the potential of commercial remotely sensed land data sources, the NASA Earth Science Enterprise (ESE) implemented an experimental Scientific Data Purchase (SDP) that solicited bids from the private sector to meet ESE-user data needs. The images from the Space Imaging IKONOS system provided a particularly good match to the current ESE missions such as Terra and Landsat 7 and therefore serve as a focal point in this analysis.

Goward, Samuel N.↗

NASA NTRS2005

Slip compensation for a Mars Rover

This paper describes the design, implementation, and experimental results of an integrated system that enables Mars rover to navigate in a high slip environment.

navigation↗

NASA NTRS2007

A Turbine-powered UAV Controls Testbed

The latest version of the NASA Flying Controls Testbed (FLiC) integrates commercial-off-the-shelf components including airframe, autopilot, and a small turbine engine to provide a low cost experimental flight controls testbed capable of sustained speeds up to 200 mph. The series of flight tests leading up to the demonstrated performance of the vehicle in sustained, autopiloted 200 mph flight at NASA Wallops Flight Facility's UAV runway in August 2006 will be described. Earlier versions of the FLiC were based on a modified Army target drone, AN/FQM-117B, developed as part of a collaboration between the Aviation Applied Technology Directorate at Fort Eustis, Virginia and NASA Langley Research Center. The newer turbine powered platform (J-FLiC) builds on the successes using the relatively smaller, slower and less expensive unmanned aerial vehicle developed specifically to test highly experimental flight control approaches with the implementation of C-coded experimental controllers. Tracking video was taken during the test flights at Wallops and will be available for presentation at the conference. Analysis of flight data from both remotely piloted and autopiloted flights will be presented. Candidate experimental controllers for implementation will be discussed. It is anticipated that flight testing will resume in Spring 2007 and those results will be included, if possible.

Motter, Mark A.↗

NASA NTRS1994

A processing centre for the CNES CE-GPS experimentation

CNES is involved in a GPS (Global Positioning System) geostationary overlay experimentation. The purpose of this experimentation is to test various new techniques in order to select the optimal station synchronization method, as well as the geostationary spacecraft orbitography method. These new techniques are needed to develop the Ranging GPS Integrity Channel services. The CNES experimentation includes three transmitting/receiving ground stations (manufactured by IN-SNEC), one INMARSAT 2 C/L band transponder and a processing center named STE (Station de Traitements de l'Experimentation). Not all the techniques to be tested are implemented, but the experimental system has to include several functions; part of the future system simulation functions, such as a servo-loop function, and in particular a data collection function providing for rapid monitoring of system operation, analysis of existing ground station processes, and several weeks of data coverage for other scientific studies. This paper discusses system architecture and some criteria used in its design, as well as the monitoring function, the approach used to develop a low-cost and short-life processing center in collaboration with a CNES sub-contractor (ATTDATAID), and some results.

Suard, Norbert↗

NASA NTRS1994

Nonlinear dynamics of drops and bubbles and chaotic phenomena

Nonlinear phenomena associated with the dynamics of free drops and bubbles are investigated analytically, numerically and experimentally. Although newly developed levitation and measurement techniques have been implemented, the full experimental validation of theoretical predictions has been hindered by interfering artifacts associated with levitation in the Earth gravitational field. The low gravity environment of orbital space flight has been shown to provide a more quiescent environment which can be utilized to better match the idealized theoretical conditions. The research effort described in this paper is a closely coupled collaboration between predictive and guiding theoretical activities and a unique experimental program involving the ultrasonic and electrostatic levitation of single droplets and bubbles. The goal is to develop and to validate methods based on nonlinear dynamics for the understanding of the large amplitude oscillatory response of single drops and bubbles to both isotropic and asymmetric pressure stimuli. The first specific area on interest has been the resonant coupling between volume and shape oscillatory modes isolated gas or vapor bubbles in a liquid host. The result of multiple time-scale asymptotic treatment, combined with domain perturbation and bifurcation methods, has been the prediction of resonant and near-resonant coupling between volume and shape modes leading to stable as well as chaotic oscillations. Experimental investigations of the large amplitude shape oscillation modes of centimeter-size single bubbles trapped in water at 1 G and under reduced hydrostatic pressure, have suggested the possibility of a low gravity experiment to study the direct coupling between these low frequency shape modes and the volume pulsation, sound-radiating mode. The second subject of interest has involved numerical modeling, using the boundary integral method, of the large amplitude shape oscillations of charged and uncharged drops in the presence of a static or time-varying electric field. Theoretically predicted non linearity in the resonant frequency of the fundamental quadrupole mode has been verified by the accompanying experimental studies. Additional phenomena such as hysteresis in the frequency response of ultrasoncially levitated droplets in the presence of a time varying electric field, and mode coupling in the oscillations of ultrasonically modulated droplets, have also been uncovered. One of the results of this ground-based research has been the identification and characterization of phenomena strictly associated with the influence of the gravitational field. This has also allowed us to identify the specific requirements for potential microgravity investigations yielding new information not obtainable on Earth.

Trinh, Eugene H.↗

NASA NTRS1991

Inverse problems in the design, modeling and testing of engineering systems

Formulations, classification, areas of application, and approaches to solving different inverse problems are considered for the design of structures, modeling, and experimental data processing. Problems in the practical implementation of theoretical-experimental methods based on solving inverse problems are analyzed in order to identify mathematical models of physical processes, aid in input data preparation for design parameter optimization, help in design parameter optimization itself, and to model experiments, large-scale tests, and real tests of engineering systems.

Alifanov, Oleg M.↗

NASA NTRS1987

Visual monitoring of autonomous life sciences experimentation

The design and implementation of a computerized visual monitoring system to aid in the monitoring and control of life sciences experiments on board a space station was investigated. A likely multiprocessor design was chosen, a plausible life science experiment with which to work was defined, the theoretical issues involved in the programming of a visual monitoring system for the experiment was considered on the multiprocessor, a system for monitoring the experiment was designed, and simulations of such a system was implemented on a network of Apollo workstations.

Blank, G. E.↗

NASA NTRS2001

Solving and Learning Soft Temporal Constraints: Experimental Scenario and Examples

Soft temporal constraint problems allow to describe in a natural way scenarios where events happen over time and preferences are associated to event distances and durations. However, sometimes such local preferences are difficult to set, and it may be easier instead to associate preferences to some complete solutions of the problem. To model everything in a uniform way via local preferences only, and also to take advantage of the existing constraint solvers which exploit only local preference use machine learning techniques which learn the local preferences from the global ones. In this paper we describe the existing framework for both solving and learning preferences in temporal constraint problems, the implemented modules, the experimental scenario, and preliminary results on some examples.

Rossi, F.↗

NASA NTRS1997

Advanced Free Flight Planner and Dispatcher's Workstation: Preliminary Design Specification

The National Aeronautics and Space Administration (NASA) has implemented the Advanced Air Transportation Technology (AATT) program to investigate future improvements to the national and international air traffic management systems. This research, as part of the AATT program, developed preliminary design requirements for an advanced Airline Operations Control (AOC) dispatcher's workstation, with emphasis on flight planning. This design will support the implementation of an experimental workstation in NASA laboratories that would emulate AOC dispatch operations. The work developed an airline flight plan data base and specified requirements for: a computer tool for generation and evaluation of free flight, user preferred trajectories (UPT); the kernel of an advanced flight planning system to be incorporated into the UPT-generation tool; and an AOC workstation to house the UPT-generation tool and to provide a real-time testing environment. A prototype for the advanced flight plan optimization kernel was developed and demonstrated. The flight planner uses dynamic programming to search a four-dimensional wind and temperature grid to identify the optimal route, altitude and speed for successive segments of a flight. An iterative process is employed in which a series of trajectories are successively refined until the LTPT is identified. The flight planner is designed to function in the current operational environment as well as in free flight. The free flight environment would enable greater flexibility in UPT selection based on alleviation of current procedural constraints. The prototype also takes advantage of advanced computer processing capabilities to implement more powerful optimization routines than would be possible with older computer systems.

Wilson, J.↗

NASA NTRS1972

Earth resources programs at the Langley Research Center. Part 1: Advanced Applications Flight Experiments (AAFE) and microwave remote sensing program

The earth resources activity is comprised of two basic programs as follows: advanced applications flight experiments, and microwave remote sensing. The two programs are in various stages of implementation, extending from experimental investigations within both the AAFE program and the microwave remote sensing program, to multidisciplinary studies and planning. The purpose of this paper is simply to identify the main thrust of the Langley Research Center activity in earth resources.

Parker, R. N.↗

NASA NTRS1975

The mini-O, a digital superhet, or a truly low-cost Omega navigation receiver

A quartz tuning fork filter circuit and some unique CMOS clock logic methods provide a very simple OMEGA-VLF receiver with true hyperbolic station pair phase difference outputs. An experimental system was implemented on a single battery-operated circuit board requiring only an external antenna preamplifier, and LOP output recorder. A bench evaluation and preliminary navigation tests indicate the technique is viable and can provide very low-cost OMEGA measurement systems. The method is promising for marine use with small boats in the present form, but might be implemented in conjunction with digital microprocessors for airborne navigation aids.

Burhans, R. W.↗

NASA NTRS1978

Evaluation of selected chemical processes for production of low-cost silicon, phases 1 and 2

A miniplant, consisting of a 5 cm-diameter fluidized-bed reactor and associated equipment was used to study the deposition parameters, temperature, reactant composition, seed particle size, bed depth, reactant throughput, and methods of reactant introduction. It was confirmed that the permissible range of fluidized-bed temperature was limited at the lower end by zinc condensation (918 C) and at higher temperatures by rapidly decreasing conversion efficiency. Use of a graded bed temperature was shown to increase the conversion efficiency over that obtained in an isothermal bed. Other aspects of the process such as the condensation and fused-salt electrolysis of the ZnCl2 by-product for recycle of zinc and chlorine were studied to provide information required for design of a 50 MT/year experimental facility. In view of the favorable technical and economic indications obtained, it was recommended that construction and operation of the 50 MT/year experimental facility be implemented.

Blocher, J. M.↗

NASA NTRS1980

Spacelab's interface to payload experiments

The Spacelab Payload Standard Modular Electronics (SPSME) program has been designed to provide a standardized set of space-qualified low-power electronic modules from which an experimenter may economically implement a command and data management system. SPSME is based on the Computer Automated Measurement and Control (CAMAC) interface standards. To the system of CAMAC, SPSME adds Spacelab interface modules, a flight qualified system crate, and an efficient light-weight power supply to produce a system compatible with the Spacelab environments, the Spacelab Command and Data Management System interface, and any experiment.

Golemon, W. F.↗

NASA NTRS1981

Fluctuations and turbulence in an electric field Bumpy Torus plasma

Fluctuation characteristics of plasma number density and electrostatic potential below the ion plasma and ion cyclotron frequencies in an electric field Bumpy Torus plasma were investigated experimentally, using digitally implemented spectral analysis techniques. The toroidal plasma was biased to high potentials by applying positive or negative voltage to electrodes located in the midplanes of two sectors of the toroidal array. The plasma was observed to be biased to 80 or 90% of the potential on the midplane electrodes, regardless of polarity. The radial electric field exceeded 1 kV/cm at the plasma boundary and penetrated inward to at least one-half of the plasma radius. When the imposed radial electric fields reached values characteristic of the experiment, the E/B drift velocities were comparable to the particle thermal velocities. The amplitude statistics of both the density and the potential fluctuations were found to be Gaussian for the most part, with near-zero skewness and a kurtosis of about 3.0. The spectral index of the density and potential fluctuations ranged from 2 to 6. The higher frequency components were found to propagate faster than the E/B drift velocity, which is the characteristic speed of the lower-frequency components.

Roth, J. R.↗

NASA NTRS1985

The implementation and use of ADA on distributed systems with high reliability requirements

The use and implementation of Ada in distributed environments in which reliability is the primary concern is investigated. Emphasis is placed on the possibility that a distributed system may be programmed entirely in Ada so that the individual tasks of the system are unconcerned with which processors they are executing on, and that failures may occur in the software or underlying hardware. A new linguistic construct, the colloquy, is introduced which solves the problems identified in an earlier proposal, the conversation. It was shown that the colloquy is at least as powerful as recovery blocks, but it is also as powerful as all the other language facilities proposed for other situations requiring backward error recovery: recovery blocks, deadlines, generalized exception handlers, traditional conversations, s-conversations, and exchanges. The major features that distinguish the colloquy are described. Sample programs that were written, but not executed, using the colloquy show that extensive backward error recovery can be included in these programs simply and elegantly. These ideas are being implemented in an experimental Ada test bed.

Knight, J. C.↗

NASA NTRS1987

Recent advances in structural dynamics of large space structures

Recent progress in the area of structural dynamics of large space structures is reviewed. Topics include system identification, large angle slewing of flexible structures, definition of scaling limitations in structural models, and recent results on a tension-stabilized antenna concept known as the hoop-column. Increasingly complex laboratory experiments guide most of the activities leading to realistic technological developments. Theoretical progress in system identification based on system realization theory resulting in unification of several methods is reviewed. Experimental results from implementation of a theoretical large-angle slewing control approach are shown. Status and results of the development of a research computer program for analysis of the transient dynamics of large angle motion of flexible structures are presented. Correlation of results from analysis and vibration tests of the hoop-column antenna concepts are summarized.

Pinson, Larry D.↗

NASA NTRS1987

Recent advances in structural dynamics of large space structures

Pinson, Larry D.↗