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At least 883 records · Page 49

All sources NASA NTRS DOE OSTI

DOE OSTI2018

Advanced Inverter Voltage Controls: Simulation and Field Pilot Findings

This report describes work performed by the Hawaiian Electric Companies and the National Renewable Energy Laboratory (NREL) to model and simulate advanced inverter grid-support functions and to validate and expand on those simulations through a field pilot study. This work builds on earlier research, referred to as the Voltage Regulation Operational Strategies study. The objective of both is to investigate functionalities available in most photovoltaic (PV) inverters to modulate active and reactive power autonomously based on local voltage measurements for the purpose of mitigating off-nominal grid voltage conditions. Specifically of interest are volt/volt-ampere reactive (VAR) control and volt/watt control, the effect of those functions on quasi-steady-state feeder voltages, and the impact of the functions on PV energy production. Because volt/VAR and volt/watt control autonomously adjust inverter output based on local conditions without requiring communication with any other devices, they are good candidates to increase PV hosting capacity when it is limited by voltage constraints in a feeder with very large numbers of PV systems.

14 SOLAR ENERGY↗

NASA NTRS2000

Neural Network Based Representation of UH-60A Pilot and Hub Accelerations

Neural network relationships between the full-scale, experimental hub accelerations and the corresponding pilot floor vertical vibration are studied. The present physics-based, quantitative effort represents an initial systematic study on the UH-60A Black Hawk hub accelerations. The NASA/Army UH-60A Airloads Program flight test database was used. A 'maneuver-effect-factor (MEF)', derived using the roll-angle and the pitch-rate, was used. Three neural network based representation-cases were considered. The pilot floor vertical vibration was considered in the first case and the hub accelerations were separately considered in the second case. The third case considered both the hub accelerations and the pilot floor vertical vibration. Neither the advance ratio nor the gross weight alone could be used to predict the pilot floor vertical vibration. However, the advance ratio and the gross weight together could be used to predict the pilot floor vertical vibration over the entire flight envelope. The hub accelerations data were modeled and found to be of very acceptable quality. The hub accelerations alone could not be used to predict the pilot floor vertical vibration. Thus, the hub accelerations alone do not drive the pilot floor vertical vibration. However, the hub accelerations, along with either the advance ratio or the gross weight or both, could be used to satisfactorily predict the pilot floor vertical vibration. The hub accelerations are clearly a factor in determining the pilot floor vertical vibration.

Kottapalli, Sesi↗

NASA NTRS1946

Free-Spinning Tunnel Tests of a 1/20-Scale Model of the Chance Vought XF6U-1 Airplane, TED No. NACA 2390

A spin investigation has been conducted in the Langley 20-foot free-spinning tunnel on a 1/20-scale model of the Chance Vought XF6U-1 airplane, The effects of control settings and movements upon the erect and inverted spin and recovery characteristics of the model were determined for the normal-fighter condition. The investigation also included tests for the take-off fighter condition (wing-tip tanks plus fuel added) spin-recovery parachutes, and simulated pilot escape. In general, for the normal-fighter condition, the model was extremely oscillatory in roll, pitch, and yaw. The angles of the fuselage varied from extremely flat to inverted attitudes, and the model rotated with the rudder in a series of short turns and glides. Recoveries by rudder reversal were rapid but the model would immediately go into a spin in the other direction. Recoveries by merely neutralizing the rudder were satisfactory when the elevator and ailerons were set to neutral, the ensuing flight path being a steep glide. Thus, it is recommended that all controls be neutralized for safe recovery from spins obtained on the airplane. With the external wing-tip tanks installed, the spins were somewhat less oscillatory in roll but recovery could not be obtained unless full-down elevator was used in conjunction with the rudder. If a spin is entered inadvertently with the full-scale airplane with external wing-tip tanks installed and if recovery is not imminent after a recovery attempt is made, it is recommended that the tanks be jettisoned and the controls neutralized.

Klinar, Walter J.↗

NASA NTRS2005

Motion Cueing Algorithm Development: Human-Centered Linear and Nonlinear Approaches

While the performance of flight simulator motion system hardware has advanced substantially, the development of the motion cueing algorithm, the software that transforms simulated aircraft dynamics into realizable motion commands, has not kept pace. Prior research identified viable features from two algorithms: the nonlinear "adaptive algorithm", and the "optimal algorithm" that incorporates human vestibular models. A novel approach to motion cueing, the "nonlinear algorithm" is introduced that combines features from both approaches. This algorithm is formulated by optimal control, and incorporates a new integrated perception model that includes both visual and vestibular sensation and the interaction between the stimuli. Using a time-varying control law, the matrix Riccati equation is updated in real time by a neurocomputing approach. Preliminary pilot testing resulted in the optimal algorithm incorporating a new otolith model, producing improved motion cues. The nonlinear algorithm vertical mode produced a motion cue with a time-varying washout, sustaining small cues for longer durations and washing out large cues more quickly compared to the optimal algorithm. The inclusion of the integrated perception model improved the responses to longitudinal and lateral cues. False cues observed with the NASA adaptive algorithm were absent. The neurocomputing approach was crucial in that the number of presentations of an input vector could be reduced to meet the real time requirement without degrading the quality of the motion cues.

Houck, Jacob A.↗

NASA NTRS1993

Analysis Of Delays In Simulation Of Flight

Report presents analysis of delays in transport of signals through various subsystems and components of flight-simulation system. Addresses all parts of simulation process and system, from analog-to-digital conversion and sampling of pilot's command input, through multiple sampling rate digital processing via transfer-function mathematical models of responses of simulated aircraft and of simulation system itself, to system output sampled at same rate as pilot's command input.

Mcfarland, R. E.↗

DOE OSTI2017

Catalyst Residence Time Distributions in Riser Reactors for Catalytic Fast Pyrolysis. Part 2: Pilot-Scale Simulations and Operational Parameter Study

Here, wsing the validated simulation model developed in part one of this study for biomass catalytic fast pyrolysis (CFP), we assess the functional utility of using this validated model to assist in the development of CFP processes in fluidized catalytic cracking (FCC) reactors to a commercially viable state. Specifically, we examine the effects of mass flow rates, boundary conditions (BCs), pyrolysis vapor molecular weight variation, and the impact of the chemical cracking kinetics on the catalyst residence times. The factors that had the largest impact on the catalyst residence time included the feed stock molecular weight and the degree of chemical cracking as controlled by the catalyst activity. Lastly, because FCC reactors have primarily been developed and utilized for petroleum cracking, we perform a comparison analysis of CFP with petroleum and show the operating regimes are fundamentally different.

09 BIOMASS FUELS↗

DOE OSTI2020

HEP ML/Optimization Go Quantum – QuantISED Pilot

This poster includes sections on: Quantum annealers for classification, Quantum gate models for classification, Software and Workflows, and Quanutm optimization for LHC physics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1976

Development and application of an atmospheric turbulence model for use in flight simulators in flight simulators

The influence of simulated turbulence on aircraft handling qualities was investigated. Pilot opinion of the handling qualities of a light general aviation aircraft were evaluated in a motion-base simulator using a simulated turbulence environment. A realistic representation of turbulence disturbances is described in terms of rms intensity and scale length and their random variations with time. The time histories generated by the proposed turbulence models showed characteristics which appear to be more similar to real turbulence than the frequently-used Gaussian turbulence model. In addition, the proposed turbulence models can flexibly accommodate changes in atmospheric conditions and be easily implemented in flight simulator studies. Six turbulence time histories, including the conventional Gaussian model, were used in an IFR-tracking task. The realism of each of the turbulence models and the handling qualities of the simulated airplane were evaluated. Analysis of pilot opinions shows that at approximately the same rms intensities of turbulence, the handling quality ratings transit from the satisfactory level, for the simple Gaussian model, to an unacceptable level for more realistic and compositely structured turbulence models.

Jacobson, I. D.↗

DOE OSTI2021

Aerosol–Ice Formation Closure: A Southern Great Plains Field Campaign

Prediction of ice formation in clouds presents one of the grand challenges in the atmospheric sciences. Immersion freezing initiated by ice-nucleating particles (INPs) is the dominant pathway of primary ice crystal formation in mixed-phase clouds, where supercooled water droplets and ice crystals coexist, with important implications for the hydrological cycle and climate. However, derivation of INP number concentrations from an ambient aerosol population in cloud-resolving and climate models remains highly uncertain. We conducted an aerosol–ice formation closure pilot study using a field-observational approach to evaluate the predictive capability of immersion freezing INPs. The closure study relies on collocated measurements of the ambient size-resolved and single-particle composition and INP number concentrations. The acquired particle data serve as input in several immersion freezing parameterizations, which are employed in cloud-resolving and climate models, for prediction of INP number concentrations. We discuss in detail one closure case study in which a front passed through the measurement site, resulting in a change of ambient particle and INP populations. We achieved closure in some circumstances within uncertainties, but we emphasize the need for freezing parameterization of potentially missing INP types and evaluation of the choice of parameterization to be employed. Overall, this closure pilot study aims to assess the level of parameter details and measurement strategies needed to achieve aerosol–ice formation closure. Furthermore, the closure approach is designed to accurately guide immersion freezing schemes in models, and ultimately identify the leading causes for climate model bias in INP predictions.

58 GEOSCIENCES↗

NASA NTRS2008

An Uncertainty Structure Matrix for Models and Simulations

Software that is used for aerospace flight control and to display information to pilots and crew is expected to be correct and credible at all times. This type of software is typically developed under strict management processes, which are intended to reduce defects in the software product. However, modeling and simulation (M&S) software may exhibit varying degrees of correctness and credibility, depending on a large and complex set of factors. These factors include its intended use, the known physics and numerical approximations within the M&S, and the referent data set against which the M&S correctness is compared. The correctness and credibility of an M&S effort is closely correlated to the uncertainty management (UM) practices that are applied to the M&S effort. This paper describes an uncertainty structure matrix for M&S, which provides a set of objective descriptions for the possible states of UM practices within a given M&S effort. The columns in the uncertainty structure matrix contain UM elements or practices that are common across most M&S efforts, and the rows describe the potential levels of achievement in each of the elements. A practitioner can quickly look at the matrix to determine where an M&S effort falls based on a common set of UM practices that are described in absolute terms that can be applied to virtually any M&S effort. The matrix can also be used to plan those steps and resources that would be needed to improve the UM practices for a given M&S effort.

Green, Lawrence L.↗

NASA NTRS1946

Free-Spinning-Tunnel Tests of a 1/18-Scale Model of the Fairchild XNQ-1 Airplane, TED No. NACA 2398

Spin tests have been performed in the Langley 20-foot free-spinning tunnel on a 1/18-scale model of the Fairchild XNQ-1 airplane. The spin and recovery characteristics of the model were determined for the normal gross-weight loading and for two variations from this loading - center of gravity moved rearward and relative mass distribution increased along the fuselage. These tests were performed for two vertical-tail plan forms. The investigation also included simulated pilot-escape tests and rudder-force tests. The recovery characteristics of the model were satisfactory for all conditions tested by full reversal of the rudder and by simultaneous neutralization of the rudder and elevator. It was indicated that if necessary to escape from the spinning airplane, the pilot should jump from the outboard side of the fuselage and as far rearward as possible. Aa determined from spin model tests, the rudder pedal force required to reverse the rudder for recovery from the spin will be light.

Daughtridge, Lee T., Jr.↗

NASA NTRS2007

Detection of Digital Elevation Model Errors Using X-band Weather Radar

Flight in Instrument Meteorological Conditions requires pilots to manipulate flight controls while referring to a Primary Flight Display. The Primary Flight Display indicates aircraft attitude along with, in some cases, many other state variables such as altitude, speed, and guidance cues. Synthetic Vision Systems have been proposed that overlay the traditional information provided on Primary Flight Displays onto a scene depicting the location of terrain and other geo-spatial features.Terrain models used by these displays must have sufficient quality to avoid providing misleading information. This paper describes how X-band radar measurements can be used as part of a monitor, and/or maintenance system, to quantify the integrity of terrain models that are used by systems such as Synthetic Vision. Terrain shadowing effects, as seen by the radar, are compared in a statistical manner against estimated shadow feature elements extracted from the stored terrain model from the perspective of the airborne observer. A test statistic is defined that enables detection of errors as small as the range resolution of the radar. Experimental results obtained from two aircraft platforms hosting certified commercial-off-the-shelf X-band radars test the premise and illustrate its potential.

Young, Steven D.↗

DOE OSTI2021

Peer-to-Peer Energy Systems for Connected Communities: A Review of Recent Advances and Emerging Challenges

After a century of relative stability of the electricity industry, extensive deployment of distributed energy resources and recent advances in computation and communication technologies have changed the nature of how we consume, trade, and apply energy. The power system is facing a transition from its traditional hierarchical structure to a more deregulated model by introducing new energy distribution models such as peer-to- peer (P2P) sharing for connected communities. The proven effectiveness of P2P sharing in benefiting both prosumers and the grid has been demonstrated in many studies and pilot projects. However, there is still no extensive implementation of such sharing models in today’s electricity markets. This paper aims to shed some light on this gap through a comprehensive overview of recent advances in the P2P energy system and an insightful discussion of the challenges that need to be addressed in order to establish P2P sharing as a viable energy management option in today’s electricity market. To this end, in this article, we provide some background on different aspects of P2P sharing. Then, we discuss advances in P2P sharing through a systematic domain-based classification. We also review different pilot projects on P2P sharing across the globe. Finally, we identify and discuss a number of challenges that need to be addressed for scaling up P2P sharing in the electricity market followed by concluding remarks at the end of the paper.

Tushar, Wayes↗

DOE OSTI2016

Evaluating the Maturity of Cybersecurity Programs for Building Control Systems

The cyber-physical security threat to buildings is complex, non-linear, and rapidly evolving as operational and information technologies converge and connect buildings to cyberspace. Cyberattacks on buildings can exploit smart building controls and breach corporate networks, causing financial and reputational damage. This may result in the loss of sensitive building information or the disruption of, or damage to, the systems necessary for the safe and efficient operation of buildings. For the buildings and facility infrastructure, there is a need for a robust national cybersecurity strategy for buildings, guidance on the selection and implementation of appropriate cybersecurity controls for buildings, an approach to evaluate the maturity and adequacy of the cybersecurity programs. To provide an approach for evaluating the maturity of the cybersecurity programs for building control systems, the US Department of Energy’s widely used Cybersecurity Capability and Maturity Model (C2M2) has been adapted into a building control systems version. The revised model, the Buildings-C2M2 (B-C2M2) provides maturity level indicators for cybersecurity programmatic domains. A “B-C2M2 Lite” version allows facility managers and building control system engineers, or information technology personnel to perform rapid self-assessments of their cybersecurity program. Both tools have been pilot tested on several facilities. This paper outlines the concept of a maturity model, describes the B-C2M2 tools, presents results and observations from the pilot assessments, and lays out plans for future work.

Glantz, Clifford S.↗

DOE OSTI2016

Water-Quality Issues Related to Uranium In Situ Recovery Sites

Batch tests, column tests, and predictive reactive transport modeling can be done before ISR begins as part of the decision making/permitting process by bracketing possible post-restoration conditions; Help address stakeholder concerns; The best predictions require actual restored groundwater in contact with the downgradient solid phase; Resulting modeling provides a range of natural attenuation rates and assists with designing the best locations and time frames for continued monitoring; Field pilot tests are the best field-scale data and can provide the best model input and calibration data

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1974

Landing approach evaluation of an integrated CRT display for general aviation aircraft

A flight director adaptable to general aviation aircraft was evaluated for the landing approach task in a twin turbojet business aircraft. The flight director combined aircraft heading, pitch and roll atitude, and ILS (Instrument Landing System) signals into a single picture on a small cathode ray tube (CRT) to give the pilot an integrated picture of the aircraft situation. The display is unique in that it presents the information on a CRT and gives quasi-command signals to the pilot. The particular display investigated was a preproduction version of the Kaiser Model FP-50 flight director. Approaches made with visual references only, with a conventional ILS displacement instrument, and with the CRT display were compared in terms of tracking performance and pilot workload. Tracking performance of three research pilots using the CRT display was superior to that using the conventional ILS instrument and comparable to that under VFR conditions. Pilot workload (based on pilot comments) was not clearly decreased.

Talbot, P. D.↗

NASA NTRS1984

Simulation validation of the XV-15 tilt-rotor research aircraft

The results of a simulation validation program of the XV-15 tilt-rotor research aircraft are detailed, covering such simulation aspects as the mathematical model, visual system, motion system, cab aural system, cab control loader system, pilot perceptual fidelity, and generic tilt rotor applications. Simulation validation was performed for the hover, low-speed, and sideward flight modes, with consideration of the in-ground rotor effect. Several deficiencies of the mathematical model and the simulation systems were identified in the course of the simulation validation project, and some were corrected. It is noted that NASA's Vertical Motion Simulator used in the program is an excellent tool for tilt-rotor and rotorcraft design, development, and pilot training.

Ferguson, S. W.↗

DOE OSTI2019

NREL's Capabilities in Modeling and Simulation of Thermal and Catalytic Conversion Processes

The Thermal and Catalytic Process Development Unit at NREL has state-of-the-art equipment for thermochemical process development and testing, ranging from catalyst and feedstock characterizations to bench-scale reactors to pilot plants. Within this facility NREL's thermal and catalytic simulation and modeling team integrates experimental and computational capabilities to address the complexities of real biomass and waste streams, enabling development of renewable energy technologies. This fact sheet summarizes the core capabilities and applications.

09 BIOMASS FUELS↗