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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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At least 289 records · Page 16

All sources NASA NTRS DOE OSTI

NASA NTRS1996

Flight Test of a Propulsion-Based Emergency Control System on the MD-11 Airplane with Emphasis on the Lateral Axis

A large, civilian, multi-engine transport MD-11 airplane control system was recently modified to perform as an emergency backup controller using engine thrust only. The emergency backup system, referred to as the propulsion-controlled aircraft (PCA) system, would be used if a major primary flight control system fails. To allow for longitudinal and lateral-directional control, the PCA system requires at least two engines and is implemented through software modifications. A flight-test program was conducted to evaluate the PCA system high-altitude flying characteristics and to demonstrate its capacity to perform safe landings. The cruise flight conditions, several low approaches and one landing without any aerodynamic flight control surface movement, were demonstrated. This paper presents results that show satisfactory performance of the PCA system in the longitudinal axis. Test results indicate that the lateral-directional axis of the system performed well at high attitude but was sluggish and prone to thermal upsets during landing approaches. Flight-test experiences and test techniques are also discussed with emphasis on the lateral-directional axis because of the difficulties encountered in flight test.

Burken, John J.↗

NASA NTRS2022

Pre-Installation Acceptance (PIA) Functional Performance of the Design Verification Test (DVT) Exploration Extra-vehicular Mobility Unit (xEMU)

In an effort that began with technology investment by NASA in a few key components during the Constellation Program and then evolved to demonstrate a packaged Portable Life Support System (PLSS) as part of the Advanced Exploration Systems (AES) Program, the next evolution of the PLSS is now a key component of the Exploration Extra-vehicular Mobility Unit (xEMU) and is assembled as a Design Verification Test (DVT) unit. The xEMU has been detailed with respect to completing a demonstration on the International Space Station (ISS) with support of units for initial lunar capability. The xEMU completed the Preliminary Design Review (PDR) with subsequent Safety Review Panel (SRP) Phase I reviews in 2019-2020. The objectives for DVT are to validate requirements, train the team, learn how to fabricate the hardware with appropriate process controls, assemble the hardware, test the hardware, determine the failure mechanisms/limits of the hardware design and buy down the most risk possible for the qualification and flight phases of the development. With completion of the assembly and initial functional testing of the DVT PLSS in laboratory ambient conditions and vacuum conditions the xEMU has progressed significantly into the DVT objectives. A key part of the test sequences for DVT and all future phases is the Pre-Installation Acceptance (PIA) functional testing which validates the performance of integrated systems including: primary thermal control, auxiliary thermal control, suit ventilation, primary oxygen, secondary oxygen, power distribution, as well as caution and warning all with respect to the applied requirements. This discussion will include an overview of the assembly, summary of the PIA functional testing, lessons learned, and corrective actions implemented moving forward into the remainder of the DVT phase for xEMU.

Colin Campbell↗

NASA NTRS1979

Flight control systems development of highly maneuverable aircraft technology /HiMAT/ vehicle

The highly maneuverable aircraft technology (HiMAT) program was conceived to demonstrate advanced technology concepts through scaled-aircraft flight tests using a remotely piloted technique. Closed-loop primary flight control is performed from a ground-based cockpit, utilizing a digital computer and up/down telemetry links. A backup flight control system for emergency operation resides in an onboard computer. The onboard systems are designed to provide fail-operational capabilities and utilize two microcomputers, dual uplink receiver/decoders, and redundant hydraulic actuation and power systems. This paper discusses the design and validation of the primary and backup digital flight control systems as well as the unique pilot and specialized systems interfaces.

Petersen, K. L.↗

NASA NTRS1987

Fiber optics for controls

The challenge of those involved in control-system hardware development is to accommodate an ever-increasing complexity in aircraft control, while limiting the size and weight of the components and improving system reliability. A technology that displays promise towards this end is the area of fiber optics for controls. The primary advantages of employing optical fibers, passive optical sensors, and optically controlled actuators are weight and volume reduction, immunity from electromagnetic effects, superior bandwidth capabilities, and freedom from short circuits and sparking contacts. Since 1975, NASA Lewis has performed in-house, contract, and grant research in fiber optic sensors, high-temperature electro-optic switches, and fly-by-light control-system architecture. Passive optical sensor development is an essential yet challenging area of work and has therefore received much attention during this period. A major effort to develop fly-by-light control-system technology, known as the Fiber-Optic Control System Integration (FOCSI) program, was initiated in 1985 as a cooperative effort between NASA and DOD. Phase 1 of FOCSI, completed in 1986, was aimed at the design of a fiber-optic integrated propulsion/flight control system. Phase 2, yet to be initiated, will provide subcomponent and system development, and a system engine test. In addition to a summary of the benefits of fiber optics, the FOCSI program, sensor advances, and future directions in the NASA Lewis program will be discussed.

Seng, Gary T.↗

NASA NTRS1993

Orientation and movement in unusual force environments

A manned space mission to Mars might take as long as 1 year each way. Consequently, artificial gravity is being considered as a way of preventing the debilitating effects of long-duration exposure to microgravity on the human body. The present article discusses some of the problems associated with adapting to the rotation levels that might be used to generate artificial gravity. It also describes how exposure to background-force levels greater or less than the 1-G force of Earth gravity affects orientation and movement control. The primary emphasis of the article is that human movement and orientation control are dynamically adapted to the 1-G force background of Earth and that accommodation to altered force levels or to rotating environments requires a wide range of adaptive changes.

Parabolic Flight↗

NASA NTRS2003

Advances in Thrust-Based Emergency Control of an Airplane

Engineers at NASA's Dryden Flight Research Center have received a patent on an emergency flight-control method implemented by a propulsion-controlled aircraft (PCA) system. Utilizing the preexisting auto-throttle and engine-pressure-ratio trim controls of the airplane, the PCA system provides pitch and roll control for landing an airplane safely without using aerodynamic control surfaces that have ceased to function because of a primary-flight-control-system failure. The installation of the PCA does not entail any changes in pre-existing engine hardware or software. [Aspects of the method and system at previous stages of development were reported in Thrust-Control System for Emergency Control of an Airplane (DRC-96-07), NASA Tech Briefs, Vol. 25, No. 3 (March 2001), page 68 and Emergency Landing Using Thrust Control and Shift of Weight (DRC-96-55), NASA Tech Briefs, Vol. 26, No. 5 (May 2002), page 58.]. Aircraft flight-control systems are designed with extensive redundancy to ensure low probabilities of failure. During recent years, however, several airplanes have exhibited major flight-control-system failures, leaving engine thrust as the last mode of flight control. In some of these emergency situations, engine thrusts were successfully modulated by the pilots to maintain flight paths or pitch angles, but in other situations, lateral control was also needed. In the majority of such control-system failures, crashes resulted and over 1,200 people died. The challenge lay in creating a means of sufficient degree of thrust-modulation control to safely fly and land a stricken airplane. A thrust-modulation control system designed for this purpose was flight-tested in a PCA an MD-11 airplane. The results of the flight test showed that without any operational control surfaces, a pilot can land a crippled airplane (U.S. Patent 5,330,131). The installation of the original PCA system entailed modifications not only of the flight-control computer (FCC) of the airplane but also of each engine-control computer. Inasmuch as engine-manufacturer warranties do not apply to modified engines, the challenge became one of creating a PCA system that does not entail modifications of the engine computers.

Creech, Gray↗

NASA NTRS1986

Independent Orbiter Assessment (IOA): Analysis of the nose wheel steering subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbiter Nose Wheel Steering (NWS) hardware are documented. The NWS hardware provides primary directional control for the Orbiter vehicle during landing rollout. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. The original NWS design was envisioned as a backup system to differential braking for directional control of the Orbiter during landing rollout. No real effort was made to design the NWS system as fail operational. The brakes have much redundancy built into their design but the poor brake/tire performance has forced the NSTS to upgrade NWS to the primary mode of directional control during rollout. As a result, a large percentage of the NWS system components have become Potential Critical Items (PCI).

Mediavilla, Anthony Scott↗

DOE OSTI2023

Aero‐servo‐elastic co‐optimization of large wind turbine blades with distributed aerodynamic control devices

Abstract This work introduces automated wind turbine optimization techniques based on full aero‐servo‐elastic models and investigates the potential of trailing edge flaps to reduce the levelized cost of energy (LCOE) of wind turbines. The Wind Energy with Integrated Servo‐control (WEIS) framework is improved to conduct the presented research. Novel methods for the generic implementation and tuning of trailing edge flap devices and their controller are also introduced. Primary flap and controller parameters are optimized to demonstrate potential maximum blade tip deflection reductions of 21 % . Concurrent design optimization (i.e., co‐design) of a novel segmented wind turbine blade with trailing edge flaps and its controller is then conducted to demonstrate blade cost savings of 5 % . Additionally, rotor diameter co‐design optimization is demonstrated to reduce the LCOE by 1.3 % without significant load increases to the tower. These results demonstrate the efficacy of control co‐design optimization using trailing edge flaps, and the entirety of this work provides a foundation for numerous control co‐design‐oriented studies for distributed aerodynamic control devices.

17 WIND ENERGY↗

NASA NTRS1991

Feasibility of using a knowledge-based system concept for in-flight primary-flight-display research

Flight test results have been obtained which demonstrate the feasibility and desirability of using knowledge-based systems architectures for flight test investigations of primary flight display information management-related issues. LISP-based software was used for real-time operation of the primary flight display. The two integrated knowledge-based systems designed to control the primary flight displays were implemented aboard a NASA-Langley B-737. The programmer is noted to be capable of more easily developing initial systems via the present method than with more conventional techniques.

Ricks, Wendell R.↗

DOE OSTI2020

Smart Contract-Defined Secondary Control and Co-Simulation for Smart Solar Inverters using Blockchain Technology

This paper proposes a cooperative control approach using blockchain technology for solar inverters in a photovoltaic system. Moreover, a co-simulation method for smart inverters and a blockchain network is studied. The blockchain assisted-smart inverter (BASI) consists of a solar inverter and an internet of things device as a client node of a blockchain network, which can fully utilize emerging blockchain technologies such as distributed ledger, security functions, and smart contract. The control includes a primary-level droop control in a BASI and smart contract-defined secondary-level supervisory control in a secured blockchain network. The concept of the proposed smart contract-defined control approach is validated by simulation studies using the cyber-physical co-simulation testbed built-in MATLAB/Simulink in a PC interfacing with a Hyperledger-Fabric blockchain software implemented in a PC.

14 SOLAR ENERGY↗

NASA NTRS1996

Summary Report of Mission Acceleration Measurements for STS-73, Launched October 20, 1995

The microgravity environment of the Space Shuttle Columbia was measured during the STS-73 mission using accelerometers from five different instruments: the Orbital Acceleration Research Experiment, the Space Acceleration Measurement System, the Three-dimensional Microgravity Accelerometer, the Microgravity Measuring Device, and Suppression of Transient Accelerations by Levitation Evaluation System. The Microgravity Analysis Workstation quasi-steady environment calculation and comparison of this calculation with Orbital Acceleration Research Experiment data was used to assess how appropriate a planned attitude was expected to be for one Crystal Growth Facility experiment sample. The microgravity environment related to several different Orbiter, crew, and experiment operations is presented and interpreted in this report. Data are examined to show the effects of vernier reaction control system jet firings for Orbiter attitude control. This is compared to examples of data when no thrusters were firing, when the primary reaction control system jets were used for attitude control, and when single vernier jets were fired for test purposes. In general, vernier jets, when used for attitude control, cause accelerations in the 3 x 10(exp -4) g to 7 x 10(exp -4) g range. Primary jets used in this manner cause accelerations in the 0.01 to 0.025 g range. Other significant disturbance sources characterized are water dump operations, with Y(sub b) axis acceleration deviations of about 1 x 10(exp -6) g; payload bay door opening motion, with Y(sub o) and Z(sub o) axis accelerations of frequency 0.4 Hz; and probable Glovebox fan operations with notable frequency components at 20, 38, 43, 48, and 53 Hz. The STS-73 microgravity environment is comparable to the environments measured on earlier microgravity science missions.

Rogers, Melissa J. B.↗

DOE OSTI2023

Rapidly Viable Sustained Grid

Rapid recovery of power flow, possibly after a blackout, is a crucial need arising in scenarios that are increasingly becoming more frequent; here, solutions for rapid viability of power while the grid is being restored are urgently needed to keep critical infrastructure (CI) online. Increasingly, after the initial recovery phase, sustenance of reliable power requires assistive services to the grid for long periods of time. Even though the need is urgent, there is only sparse effort present toward a comprehensive framework/strategy for making power rapidly viable with an emphasis on sustained grid ancillary services; which is the focus of this proposal. The proposed concept envisions four phases. In the first phase, when a large portion of power is disrupted (see Figure 1(a)), emphasis is on bringing CI online with the objective of maximizing the time horizon of power viability using resources available at the CI. In the second phase (Figure 1(b)), neighborhood resources are tightly coordinated that forms the CI’s central-core (CC) to provide guaranteed viability of CI over a longer horizon. In the third phase, self-organizing power networks are expanded in a distributed layer supporting the central-core (Figure 1(c)). In the fourth phase, separate CI-networks coalesce and are controlled in a coordinated fashion to provide grid ancillary services (AS), such as primary frequency control and enhancing grid resiliency. With time, system efficiencies and penetration of renewables increase, while the time-horizon of guaranteed sustenance of CI is maximized. Under proposed work, the concept will be instantiated with a focus on medical centers as CI. Comprehensive power hardware in the loop strategies and emulated field tests will guide and validate devised solutions. A strong T2M effort to commercialize resulting technology is outlined. The proposed technology will be transformative for the grid. It will fundamentally change the way large contingencies are managed where power systems and critical infrastructure transition from being fragile to being robust using intelligent, self-organizing control for coordinating resources, enhanced resiliency and use of sustainable energy sources.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NASA NTRS1987

Aircraft control position indicator

An aircraft control position indicator was provided that displayed the degree of deflection of the primary flight control surfaces and the manner in which the aircraft responded. The display included a vertical elevator dot/bar graph meter display for indication whether the aircraft will pitch up or down, a horizontal aileron dot/bar graph meter display for indicating whether the aircraft will roll to the left or to the right, and a horizontal dot/bar graph meter display for indicating whether the aircraft will turn left or right. The vertical and horizontal display or displays intersect to form an up/down, left/right type display. Internal electronic display driver means received signals from transducers measuring the control surface deflections and determined the position of the meter indicators on each dot/bar graph meter display. The device allows readability at a glance, easy visual perception in sunlight or shade, near-zero lag in displaying flight control position, and is not affected by gravitational or centrifugal forces.

Dennis, Dale V.↗

NASA NTRS2010

The Role of the Exploration Science Officer in Lunar Surface Operations

A review has been performed of exploration science and payload operations during the Apollo and Space Shuttle programs to extract information of potential usefulness to the Constellation program. That work has resulted in creation of the concept for a unique type of flight controller: the exploration science officer. The controller s primary responsibility is to integrate the tasks and goals of the spacecraft flight control team and the science team in order to maximize science return while maximizing crew safety. Far from being just a mouthpiece for either team, this individual must be fluent in the knowledge and language of two communities: spacecraft operations and planetary science. Responsibilities begin during the requirements phase of vehicle and lunar surface systems development and continue through development, training, planning, mission execution, and post-flight mission phases.

John H Osborn↗

NASA NTRS1975

ATS-6 - Spacecraft Attitude Precision Pointing and Slewing Adaptive Control Experiment

The primary objective of the Spacecraft Attitude Precision Pointing and Slewing Adaptive Control (SAPPSAC) experiment is to establish feasibility and evaluate capabilities of a ground-based spacecraft attitude control system, wherein RF command and telemetry links, together with a ground station on-line minicomputer, perform closed loop attitude control of the Applications Technology Satellite-6 (ATS-6). The ground processor is described, including operational characteristics and the controller software. Attitude maneuvers include precision pointing to fixed targets, slewing between targets, and generation of prescribed ground tracks. Test results show high performance and reliability for over 30 hours of on-line control with no serious anomalies. Attitude stabilization relative to a prescribed target has been achieved to better than 0.007 deg in pitch and roll and 0.02 deg in yaw for a period of 43 min. Ground tracks were generated which had maximum latitude/longitude deviations less than 0.15 deg from reference.

Isley, W. C.↗

NASA NTRS1994

Basic features of the STS/Spacelab vibration environment

The Space Shuttle acceleration environment is characterized. The acceleration environment is composed of a residual or quasi-steady component and higher frequency components induced by vehicle structural modes and the operation of onboard machinery. Quasi-steady accelerations are generally due to atmospheric drag, gravity gradient effects, and rotational forces. These accelerations tend to vary with the orbital frequency (approx. 10(exp -4) Hz) and have magnitudes less than or equal to 10(exp -6) g(sub 0) (where 1 g(sub 0) is terrestrial gravity). Higher frequency g-jitter is characterized by oscillatory disturbances in the 1-100 Hz range and transient components. Oscillatory accelerations are related to the response of large flexible structures like antennae, the Spacelab module, and the Orbiter itself, and to the operation of rotating machinery. The Orbiter structural modes in the 1-10 Hz range, are excited by oscillatory and transient disturbances and tend to dominate the energy spectrum of the acceleration environment. A comparison of the acceleration measurements from different Space Shuttle missions reveals the characteristic signature of the structural modes of the Orbiter overlaid with mission specific hardware induced disturbances and their harmonics. Transient accelerations are usually attributed to crew activity and Orbiter thruster operations. During crew sleep periods, the acceleration levels are typically on the order of 10(exp -6) g(sub 0) (1 micro-g). Crew work and exercise tend to raise the accelerations to the 10(exp -3) g(sub 0) (1 milli-g) level. Vernier reaction control system firings tend to cause accelerations of 10(exp -4) g(sub 0), while primary reaction control system and Orbiter maneuvering system firings cause accelerations as large as 10(exp -2) g(sub 0). Vibration isolation techniques (both active and passive systems) used during crew exercise have been shown to significantly reduce the acceleration magnitudes.

Baugher, Charles R.↗

DOE OSTI2020

Impedance-Based Prediction of SSR-Generated Harmonics in Doubly-Fed Induction Generators

Doubly-fed induction generators (DFIGs) are prone to subsynchronous resonance (SSR) with series-compensated transmission lines and experiencing SSR-generated harmonics of wide-ranging magnitudes. This paper presents a large-signal impedance-based approach for the prediction of the magnitude of SSR-generated harmonics in DFIGs. Note that the large-signal impedance of a network shows variation in its impedance response with the magnitude of perturbation at its terminals. It is discovered in this paper that the impedance of a series-compen- sated transmission line starts changing with the magnitude of SSR because of the metal-oxide varistor-based protection of series capacitors in the line. The changing line impedance halts the growth of the SSR beyond a certain point, where the DFIG forms a limit-cycle mode and emits harmonics at the SSR frequency. The discovered role of the protection of series capacitors in SSR not only enables the prediction of SSR-generated harmonics but also can be used for the timely detection of an SSR event to avoid system disruption and sudden loss of bulk generation. The large- signal impedance-based prediction of SSR-generated harmonics in DFIG-based wind and hydro generators is demonstrated using numerical simulations of a 2.5-MVA, 690-V DFIG supplying to a series-compensated transmission line.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2025

Learning the factors controlling mineral dissolution in three-dimensional fracture networks: applications in geologic carbon sequestration

We perform a set of high-fidelity simulations of geochemical reactions within three-dimensional discrete fracture networks (DFN) and use various machine learning techniques to determine the primary factors controlling mineral dissolution. The DFN are partially filled with quartz that gradually dissolves until quasi-steady state conditions are reached. At this point, we measure the quartz remaining in each fracture within the domain as our primary quantity of interest. We observe that a primary sub-network of fractures exists, where the quartz has been fully dissolved out. This reduction in resistance to flow leads to increased flow channelization and reduced solute travel times. However, depending on the DFN topology and the rate of dissolution, we observe substantial variability in the volume of quartz remaining within fractures outside of the primary subnetwork. This variability indicates an interplay between the fracture network structure and geochemical reactions. We characterize the features controlling these processes by developing a machine learning framework to extract their relevant impact. Specifically, we use a combination of high-fidelity simulations with a graph-based approach to study geochemical reactive transport in a complex fracture network to determine the key features that control dissolution. We consider topological, geometric and hydrological features of the fracture network to predict the remaining quartz in quasi-steady state. We found that the dissolution reaction rate constant of quartz and the distance to the primary sub-network in the fracture network are the two most important features controlling the amount of quartz remaining. This study is a first step towards characterizing the parameters that control carbon mineralization using an approach with integrates computational physics and machine learning.

54 ENVIRONMENTAL SCIENCES↗