A data reduction technique for distribution analysis
Data reduction technique for distribution analysis
DISTRIBUTION FUNCTION↗
SEARCH · Engineering Papers
Results for “REDUCTION”
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.
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U. S. Coast and Geodetic Survey - NASA GEOMAGNETIC data reduction program
Geomagnetic data reduction program, and World Data Center information interchange
GEOMAGNETISM↗
Data reduction techniques for spectral radiance analysis
Data reduction techniques for spectral radiance analysis
DATA REDUCTION↗
A theoretical study of meteoric trajectories and processes, including examination of the incidence and characteristics of photographic meteors by reduction of about 600 data points
Automatic reduction procedure for photographic meteor data - star identification
ASTRONOMICAL PHOTOGRAPHY↗
A computerized data-reduction technique for Langmuir probe analysis of electron temperature variations in the exhaust of a magnetoplasmadynamic arc
Computerized data reduction techniques for obtaining local electron temperature variations in plasma beams produced by magnetoplasmadynamic accelerators
DATA REDUCTION↗
Two photoviscoelasticity experiments using analog data reduction.
Tensile analog data reduction technique for determination of principal stress differences history at points of two nonhomogeneous photoviscoelastic models
ANALOG DATA↗
An application of automatic carpet plotting to wind-tunnel data reduction.
Automatic carpet plotting applicability to reduction of wind tunnel data
DATA REDUCTION↗
The reduction of noise and dark current in photomultiplier tubes by magnetic defocusing.
Noise and dark current reduction in photomultiplier tubes by magnetic defocusing
MAGNETIC CONTROL↗
Drag Reduction Devices for Aircraft (Latest Citations from the Aerospace Database)
The bibliography contains citations concerning the modeling, application, testing, and development of drag reduction devices for aircraft. Slots, flaps, fences, large-eddy breakup (LEBU) devices, vortex generators and turbines, Helmholtz resonators, and winglets are among the devices discussed. Contour shaping to ensure laminar flow, control boundary layer transition, or minimize turbulence is also covered. Applications include the wings, nacelles, fuselage, empennage, and externals of aircraft designed for high-lift, subsonic, or supersonic operation. The design, testing, and development of directional grooves, commonly called riblets, are covered in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.)
AIRCRAFT DESIGN↗
High-Energy-Density Fuel Blending Strategies and Drop Dispersion for Fuel Cost Reduction and Soot Propensity Control
The idea that low soot propensity of high-energy-density (HED) liquid sooting fuels and cost reduction of a multicomponent energetic fuel can be achieved by doping a less expensive, less sooting liquid fuel with HED is tested through numerical simulations.
low soot propensity HED cost reduction axisymmetri↗
Localized, Non-Harmonic Active Flap Motions for Low Frequency In-Plane Rotor Noise Reduction
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 motions derived from closed-loop acoustics implementations. All three approaches resulted in approximately the same noise reductions over an in-plane three-by-three microphone array installed forward and near in-plane of the rotor in the nearfield. It is also reported that using an active flap in this localized, non-harmonic manner, resulted in no more that 2% rotor performance penalty, but had the tendency to incur higher hub vibration levels.
FLAPS(CONTROL SURFACES)↗
Launch Control System Master Console Event Message Reduction
System monitoring and control (SMC) message browsers receive so many messages daily that operators do not need to see. Important messages are often mixed up among the less important ones. My job is to reduce the messages displayed in the message browser so that warning and emergency messages can be seen easily and therefore, responded promptly. There are multiple methods to achieve this. Firstly, duplicate messages should not appear many times in the message browser. Instead, the message should appear only once but with a number that counts the times that it appears. This method is called duplicate message suppression. Secondly, messages that update the most recent state (e.g. up/down) of a component should replace the old-state messages. This method is called state based message correlation. Thirdly, messages that display "normal" alarm level should be suppressed unless it's a response to an operator action. In addition to message reduction, I also work on correcting the severity level and text formats on messages.
messages↗
Initial Assessment of a Variable-Camber Continuous Trailing-Edge Flap System on a Rigid Wing for Drag Reduction in Subsonic Cruise
In this paper, we describe an initial optimization study of a Variable-Camber Continuous Trailing-Edge Flap (VCCTEF) system. The VCCTEF provides a light-weight control system for aircraft with long flexible wings, providing efficient high-lift capability for takeoff and landing, and greater efficiency with reduced drag at cruising flight by considering the effects of aeroelastic wing deformations in the control law. The VCCTEF system is comprised of a large number of distributed and individually-actuatable control surfaces that are constrained in movement relative to neighboring surfaces, and are non-trivially coupled through structural aeroelastic dynamics. Minimzation of drag results in a constrained, coupled, non-linear optimization over a high-dimension search space. In this paper, we describe the modeling, analysis, and optimization of the VCCTEF system control inputs for minimum drag in cruise. The purpose of this initial study is to quantify the expected benefits of the system concept. The scope of this analysis is limited to consideration of a rigid wing without structural flexibility in a steady-state cruise condition at various fuel weights. For analysis, we developed an optimization engine that couples geometric synthesis with vortex-lattice analysis to automate the optimization procedure. In this paper, we present and describe the VCCTEF system concept, optimization approach and tools, run-time performance, and results of the optimization at 20%, 50%, and 80% fuel load. This initial limited-scope study finds the VCCTEF system can potentially gain nearly 10% reduction in cruise drag, provides greater drag savings at lower operating weight, and efficiency is negatively impacted by the severity of relative constraints between control surfaces.
trailing edge flaps↗
Preliminary Assessment of Optimal Longitudinal-Mode Control for Drag Reduction through Distributed Aeroelastic Shaping
The emergence of advanced lightweight materials is resulting in a new generation of lighter, flexible, more-efficient airframes that are enabling concepts for active aeroelastic wing-shape control to achieve greater flight efficiency and increased safety margins. These elastically shaped aircraft concepts require non-traditional methods for large-scale multi-objective flight control that simultaneously seek to gain aerodynamic efficiency in terms of drag reduction while performing traditional command-tracking tasks as part of a complete guidance and navigation solution. This paper presents results from a preliminary study of a notional multi-objective control law for an aeroelastic flexible-wing aircraft controlled through distributed continuous leading and trailing edge control surface actuators. This preliminary study develops and analyzes a multi-objective control law derived from optimal linear quadratic methods on a longitudinal vehicle dynamics model with coupled aeroelastic dynamics. The controller tracks commanded attack-angle while minimizing drag and controlling wing twist and bend. This paper presents an overview of the elastic aircraft concept, outlines the coupled vehicle model, presents the preliminary control law formulation and implementation, presents results from simulation, provides analysis, and concludes by identifying possible future areas for research
aeroelastic↗
Parametric Investigation on the Use of Lateral and Logitudinal Rotor Trim Flapping for Tiltrotor Noise Reduction
This paper presents an acoustics parametric study of the effect of varying lateral and longitudinal rotor trim flapping angles (tip-path-plane tilt) on noise radiated by an isolated 26-ft diameter proprotor, similar to that of the AW609 tiltrotor, in edgewise flight. Three tip-path-plane angle of attack operating conditions of -9, 0 and 6 deg, at 80 knots, were investigated. Results showed that: 1) minimum noise was attained for the tip-path-plane angle of attack value of -9 deg, and 2) changing the cyclic trim state (i.e., controls) altered the airloads and produced noticeable changes to the low-frequency (LF) and blade-vortex interaction (BVI) radiated-noise magnitude and directionality. In particular, by trimming the rotor to a positive (inboard) lateral flapping angle of 4 deg, further reductions up to 3 dB in the low-frequency noise sound pressure level were attained without significantly impacting the BVI noise for longitudinal tip-path-plane angles of -9 and 6 deg.
Noise Reduction↗
Risk Reduction for the System Design of an Enhanced MMRTG
Engineering of an enhanced Multi-Mission Radioisotope Thermoelectric Generator (eMMRTG) began 3 years ago with agreement between the U.S. National Aeronautics and Space Administration (NASA) and the U.S. Department of Energy (DOE). The Jet Propulsion Laboratory is leading the transfer of skutterudite thermoelectric couple technology to industry and leading the systems engineering of the proposed eMMRTG. Should NASA fund the flight development of an eMMRTG, the DOE would lead the flight system development. The analytical models and design of the MMRTG have been enhanced to use skutterudite couples developed at Jet Propulsion Laboratory over the last two decades. This required a thorough evaluation of the MMRTG design, and concurrent engineering of an enhanced MMRTG to shed light on potential design issues or risks. At the end of the U.S. fiscal year (FY) 2015, a complete catalog of risks was produced. Tests, hardware development, and analyses have now been put in place to mitigate those risks to acceptable levels. Few risks can ever be truly eliminated unless a design is modified to eliminate specific risks and not introduce more severe risks. The design imperative for the eMMRTG is to change only a few MMRTG features; therefore, risks can largely only be mitigated, not eliminated, through design changes. However, many risks can be effectively - though not totally - eliminated without design changes. This paper briefly describes some of the documented risks and mitigations or reduction approaches to be applied in the coming 3 years, on the way to completing the eMMRTG concept.
eMMRTG↗
A Krylov Model Reduction Methodology for Articulated, Multi-Flexible Body Structures
A Krylov model reduction methodology for articulated, multi-flexible body structures is proposed in this research. This methodology generates reduced-order component models without solving any eigenvalue problem.
Model↗
DC Modeling of 4H-SiC JFET Gate Length Reduction at 500°C
The development of robust, high-performance integrated circuits (ICs) will enable numerous potential NASA missions of current interest, including long-duration robotic missions exploring the 460 °C surface of Venus. Currently, NASA is looking towards SiC-based devices to provide such a solution. However, the current NASA silicon carbide (SiC) JFET device with a channel length of 6μm (for recently fabricated Gen. 11 ICs) limits on mission relevant circuit capabilities [1]. In this study, we combined experiments with simulations to explore two straightforward fabrication strategies to reduce the SiC JFET channel length while maintaining turn-off behavior (Fig. 1a) needed to realize 500 °C circuit operation. The first fabrication strategy uses a shallow self-align nitrogen implant (Figure 1b) along the device's top surface but not below the gate combined with a high-dose phosphorous implant directly below the source and drain contacts. For the second fabrication strategy (Figure 1c), the high-dose phosphorous implants extended from below the contacts all the way up to the gate edges. Simulations guided gate length reductions without significant degradation in the turn-off performance. In total 12 SiC JFET variants implementing using the different fabrication strategies, gate lengths, and n-channel epilayer thickness were implemented in our simulation framework implemented in COMSOL. Since the COMSOL database does not have the material properties for 4H-SiC, these parameters were taken from the literature and implemented in COMSOL. The empirical models [2] for incomplete ionization, Auger recombination, low field mobility, and Shockley-Read-Hall recombination were implemented to account for material-specific device behavior.
4H-SiC JFET↗