SEARCH · Engineering Papers

Results for “control authority”

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 595 records · Page 33

All sources NASA NTRS DOE OSTI

NASA NTRS1972

Control of functional differential equations with function space boundary conditions.

The results of various authors dealing with problems involving functional differential equations with terminal conditions in function space are reviewed. The review includes not only very recent results, but also some little known results of Soviet mathematicians prior to 1970. Particular attention is given to results concerning controllability, existence of optimal controls, and necessary and sufficient conditions for optimality.

Banks, H. T.↗

DOE OSTI2021

Tier 2 Safety Basis Document: Weapons and Complex Integration - Building 225

This Safety Basis Document (SBD) covers operations in the Weapons and Complex Integration (WCI) Building 225 (B225) facility. B225 is located in the southwestern quadrant of Lawrence Livermore National Laboratory (LLNL) and is operated and owned by WCI. This SBD satisfies the requirements of LLNL ES&H Manual Document 3.1, Nonnuclear Safety Basis Program (Ref. 2). B225 is classified as a Low Hazard Facility based on the inventory of radiological materials. Other hazards in B225: chemicals, radiation generating devices, and industrial hazards are managed at the Light Science and Industry (LSI) level. Biological and explosive hazards are not authorized in B225. There are four general Administrative Controls (ACs) identified as the B225 Operational Safety Requirements (OSRs). These administrative controls are deemed sufficient to ensure safe operations with respect to co-located workers and the public. Other safety features and administrative requirements are required by the LLNL ES&H Manual, including those to protect the facility workers and the environment, but these have not been selected as credited controls to protect the co-located workers or the public, which are the target populations of concern for the SBD.

61 RADIATION PROTECTION AND DOSIMETRY↗

NASA NTRS1972

A simulator evaluation of the use of spoilers on a light aircraft

A fixed-base flight simulator was used to evaluate wing spoilers for longitudinal flight path control on a modified Cessna Cardinal aircraft. Spoilers which generated the proper pitching moment to maintain aircraft trim C sub L constant could be used as an effective descent rate control. More than 100 simulated ILS approaches were flown by evaluation pilots using both conventional methods and spoiler descent rate control. Three spoiler control schemes were evaluated during the ILS approaches. Using the spoilers for control, instrument approaches could be flown smoothly and precisely with constant airspeed and pitch attitude. While the spoilers could adequately control ILS approaches, a spoiler system with greater authority would be desirable for use in visual approaches.

Brainerd, C. H.↗

NASA NTRS1985

Management: A bibliography for NASA managers

This bibliography lists 706 reports, articles, and other documents introduced into the NASA scientific and technical information system in 1984. Entries, which include abstracts, are arranged in the following categories: human factors and personnel issues; management theory and techniques; industrial management and manufacturing; robotics and expert systems; computers and information management; research and development; economics, costs, and markets; logistics and operations management; reliability and quality control; and legality, legislation, and policy. Subject, personal author, corporate source, contract number, report number, and accession number indexes are included.

Source record↗

NASA NTRS1987

On the dynamics of manipulators in space using the virtual manipulator approach

A virtual manipulator (VM) concept has been developed recently for the modeling of manipulators working in space. The authors show that the VM facilitates planning and control of the motions of manipulators mounted on spacecraft, minimizing the degrading consequences of manipulator/vehicle dynamic interactions.

Vafa, Z.↗

NASA NTRS1991

Robust controller design for structures with displacement sensors

The passivity theorem may be used to design robust controllers for structures with positive transfer functions. The authors obtain a similar result for systems with displacement sensors. In order to illustrate the ideas discussed, a specific second-order dynamic system is considered.

Morris, K. A.↗

NASA NTRS1950

A Description of the Design of Highly Swept Propeller Blades

A description of the two swept propellers investigated in the Langley 8-foot high-speed tunnel is presented, together with the discussions of the numerous assumptions and analyses on which the designs of these propellers are based. The blades are swept considerably along the entire blade radius and, in order to allow for reductions in the maximum stresses, are swept forward inboard and backward outboard. The blades have been designed on the basis of the blade-element method primarily to have subcritical efficiencies at the highest possible forward speed. The designs have been controlled primarily by the stresses in the blades. (author)

Whitcomb, Richard T↗

NASA NTRS1996

Adaptation of Motility Analysis Apparatus for Space Science and Microgravity Ground-Based Experiments

Previous space flight studies have described unfavorable effects of microgravity on testicular morphology and spermatogenesis (Cosmos 1887 Biosputnik flight, 9/29/87 - 10/12/87). The flight animals demonstrated small reductions in testicular and epididymal size, the phenomenon explained as resulting water loss. Yet, light microscopic histological preparations revealed few spermatozoa in the rete testis of the flight males compared to control animals. The cause for this finding was subjectively assessed to be due to "the anatomical dislocation of the organs... and a disturbance in testicular blood supply". Unfortunately, the reported effects of microgravity on the reproductive processes (particularly within males) are few and divergent. If habitation in space is a futuristic goal, more objective testing (of male and female gametes) in a microgravity environment will provide insight to the developmental potential of these reproductive cells. As part of the Marshall Space Flight Centers' Summer Faculty Fellowship Program within the Biophysics Branch, a key component of the research investigation was to develop a test to evaluate individual cell motility and orientation in varying gravitational environments, using computerized assessment of sperm cell concentration, morphology and motility to provide objective, quantitative experimental control. In previous work performed jointly by the author and a NASA colleague, it has been shown that macroscopic motile aggregates of spermatozoa were not altered by the absence of microgravity. Variations in the number of normal versus abnormal sperm due to microgravity influences have yet to be established. It is therefore of interest to monitor the cytoskeletal matrix (microtubulin) of these organisms as a possible indicator of cell viability and/or function.

Johnson, Jacqueline U.↗

NASA NTRS1999

Performance Modeling of a Pilot in a Free Flight Mode: A Free Flight Self-Separation Cancellations Due to the Requirement for Procedural Intervention - 1

Developments are being made that allow pilots to have more flexibility over the control of their aircraft. This new concept is called Free Flight. Free Flight strives to move the current air traffic system into an age where space technology is used to its fullest potential. Self-separation is one part of the Free Flight system. Self-separation provides pilots the opportunity to choose their own route to reach a specified destination provided that they maintain the 'minimum required separation distance between airplanes. In the event that pilots are unable to maintain separation, controllers will need to have the aircraft separation authority passed back to them. This situation is known as a procedural intervention point. This project attempted to examine and diagnose those particular situations in an effort to avoid reaching a procedural intervention point in the near future. Crews that reached procedural intervention points were compared with crews that made similar maneuver types in the same scenario, but did not reach procedural intervention points. Results showed that there were no significant differences between crews in a high-density acute angle flight conditions. However, significant differences in maneuver times, following the detection of an intruder aircraft and following the time the intruder aircraft came into view, were found in a low-density, acute angle scenario.

Ntuen, Celestine A.↗

NASA NTRS1939

A Glimpse of Scientific Research on Fundamental Problems of Military and Civil Aeronautics

Among the outstanding accomplishments of the last century is man's conquest of the air. That conquest began in 1903 when the Wright brothers made the first successful flight of an airplane at Kitty Hawk, N. C. Five years later the United States Government purchased its first airplane for the use of the Army, and began the training of officers for military flying. During the years immediately preceding the outbreak of the World War the Government and a meager aircraft industry had made important progress, but the Government, practically the only customer, had purchased less than 100 airplanes. In the meantime, leading European nations, sensing acutely the potentialities of aircraft in warfare, had made greater progress and had begun laying the foundations for the new science of aeronautics. The World War gave a remarkable impetus to the development of aeronautics and emphasized the need for organized research on the fundamental problems of flight. By act of Congress approved March 3, 1915, the National Advisory Committee for Aeronautics was created and charged with the duty of supervising, directing, and conducting fundamental scientific research and experiment in aeronautics. With the farsighted support of the Congress the Committee has led the world in the development of unique aeronautical research facilities in its laboratories at Langley Field, Va. The research programs include problems initiated by the Committee and its subcommittees and also investigations requested by the Army, the Navy, and the Civil Aeronautics Authority. The results of researches conducted under one control, serve without duplication of effort, the needs of all branches of aviation, civil and military, and exert a profound influence on the progress of aeronautics by improving the performance, efficiency, and safety of aircraft. A brief description of the results of some of the committee's researches and of the equipment employed will be found in the following pages.

Source record↗

NASA NTRS2016

Benefits of Using Pairwise Trajectory Management in the Central East Pacific

Pairwise Trajectory Management (PTM) is a concept that utilizes airborne and ground-based capabilities to enable airborne spacing operations in oceanic regions. The goal of PTM is to use enhanced surveillance, along with airborne tools, to manage the spacing between aircraft. Due to the enhanced airborne surveillance of Automatic Dependent Surveillance-Broadcast (ADS-B) information and reduced communication, the PTM minimum spacing distance will be less than distances currently required of an air traffic controller. Reduced minimum distance will increase the capacity of aircraft operations at a given altitude or volume of airspace, thereby increasing time on desired trajectory and overall flight efficiency. PTM is designed to allow a flight crew to resolve a specific traffic conflict (or conflicts), identified by the air traffic controller, while maintaining the flight crew's desired altitude. The air traffic controller issues a PTM clearance to a flight crew authorized to conduct PTM operations in order to resolve a conflict for the pair (or pairs) of aircraft (i.e., the PTM aircraft and a designated target aircraft). This clearance requires the flight crew of the PTM aircraft to use their ADS-B-enabled onboard equipment to manage their spacing relative to the designated target aircraft to ensure spacing distances that are no closer than the PTM minimum distance. When the air traffic controller determines that PTM is no longer required, the controller issues a clearance to cancel the PTM operation.

Chartrand, Ryan↗

NASA NTRS1951

Lateral Control by Spoilers at the DVL

The present report describes the development of spoiler control at the DVL from the end of 1936 until the beginning of 1939. The authors are fully aware that the present report also forms only a contribution to the problem of spoiler control and offers at best a possibility of extrapolation regarding the behavior of the control in modern airplanes. A modern airplane (Me 109) is being reconstructed for conversion to spoiler control. Experience has shown, however, that the construction and testing of such a model requires at least a year. Thus it seems appropriate to report summarily now in order to keep the understanding and cooperation of the interested departments aroused. The following reports are only a section of a long development partly evolved abroad.

CONTROLS, SPOILERS - COMPLETE WINGS↗

NASA NTRS2018

Wing Shaping and Gust Load Controls of Flexible Aircraft: An LPV Approach

In the proposed paper, the optimum wing shape of a highly flexible aircraft under varying flight conditions will be controlled by a linear parameter-varying approach. The optimum shape determined under multiple objectives, including flight performance, ride quality, and control effort, will be determined as well. This work is an extension of work done previously by the authors, and updates the existing optimization and utilizes the results to generate a robust flight controller.

Gust Load Alleviation↗

DOE OSTI2020

Controlled removal of hydrogen atoms from H-terminated silicon surfaces

The controlled formation of dangling bond structures on a H-terminated silicon surface is the first step in an atomically precise method of fabrication of silicon quantum electronic devices. An ultrahigh vacuum scanning tunneling microscope (STM) tip is used to selectively desorb hydrogen atoms from a Si(100)-2x1:H surface by injecting electrons with the sample held at a positive bias voltage. The authors propose a lithography method that allows the STM to operate under negative bias imaging conditions and simultaneously desorb H atoms as required. A high frequency signal is added to the negative bias voltage to deliver the required energy for hydrogen removal. The resulting current at this frequency and its harmonics are filtered to minimize their effect on the operation of the STM’s feedback control loop. The authors show that the chance of tip-sample crash during the lithography process is reduced by employing this method. They also demonstrate that this approach offers a significant potential for controlled and precise removal of H atoms from a H-terminated silicon surface and thus may be used for the fabrication of practical silicon-based atomic-scale devices.

42 ENGINEERING↗

NASA NTRS2017

Managing Capital Investments and Resources for Large, Complex Satellite Development Efforts

Once the schedule was baselined and the primary, secondary, and tertiary critical paths (at least) were established: Identified what entity control which portion of the schedule reserve Dollarized the time associated with the schedule reserve and segregated it off from other budget reserves authorization to spend only came when authorization to utilize the time was given Created a process to manage the control of these resources This process was above and beyond the typical schedule controls used to monitor and maintain the day-to-day schedules Webb telescope will be the premier space observatory for astronomers worldwide,extending the tantalizing discoveries of the Hubble Space telescope• An international collaboration among NASA, the European Space Agency, and theCanadian Space Agency• The largest telescope ever placed in space, Webb will be ~100 times more powerful thanHubble• It is so big it has to fold origami-style to fit in the rocket and will unfold like a transformeronce in space• The 5-layer sunshield protects the telescope from the Sun, Earth, and Moon’s infraredradiation. It’s like having sun protection of SPF 1 million• Unprecedented infrared sensitivity will peer back in time over 13.5 billion years to see thefirst galaxies born after the Big Bang• Hubble orbits ~350 miles above the Earth; Webb will orbit the sun ~1 million miles fromEarth• Launch from French Guiana in 2018

Ryan, Richard M.↗

NASA NTRS2016

Using Computational Fluid Dynamics and Experiments to Design Sweeping Jets for High Reynolds Number Cruise Configurations

The application of a sweeping jet actuator to a circulation control system was initiated by a risk reduction series of experiments to optimize the authority of a single sweeping jet actuator. The sweeping jet design was integrated into the existing Fundamental Aerodynamic Subsonic Transonic- Modular Active Control (FAST-MAC) model by replacing the steady blowing system with an array of thirty-nine sweeping jet cartridges. A constant slot height to wing chord ratio was similar to the steady blowing configuration resulting in each actuator having a unique in size for the sweeping jet configuration. While this paper will describe the scaling and optimization of the actuators for future high Reynolds number applications, the major focus of this effort was to target the transonic flight regime by increasing the amplitude authority of the actuator. This was accomplished by modifying the diffuser of the sweeping jet actuator, and this paper highlights twelve different diffuser designs. The experimental portion of this work was completed in the NASA Langley National Transonic Facility.

Jones, Gregory S.↗

NASA NTRSDate not supplied

Pterodactyl: Non-propulsive Control Systems for Future Planetary Missions

This white paper presents an assessment of control systems as it relates to state-of-the-art hypersonic entry vehicles and addresses technological advances that enable new control systems for future hypersonic entry vehicles. Advancements in deployable entry vehicle (DEV) technology, entry guidance, woven thermal protection systems, and affordable launch services make it possible to conceive of entry vehicles that optimize entry loads, maneuverability, usable payload mass and volume, and operational costs. NASA’s Space Technology Mission Directorate (STMD) is currently funding the authors on a project, Pterodactyl, that is using on-the-fly trajectory design and integrated software and hardware development to investigate non-propulsive entry control systems for precision targeting of mechanical DEVs. The authors recently reported key findings of these control systems for an asymmetric DEV to track bank commands for a lunar sample return entry.

Sarah D'Souza↗

DOE OSTI2023

Experimental investigation of advanced turbine control strategies and load-mitigation measures with a model-scale floating offshore wind turbine system

To advance the control co-design of offshore wind energy systems, the authors perform basin-scale experiments with a fully instrumented and actuated floating offshore wind turbine model. The model consists of a 1:70 scale performance-matched model of the International Energy Agency Wind Technology Collaboration Programme 15-MW reference turbine atop the VolturnUS-S semisubmersible platform. The Reference OpenSource Controller provides real-time blade pitch and generator torque control. Here we aim to develop an open data set for the validation of numerical models in predicting the influence of turbine control and load-mitigation measures. For this purpose, we measure the effects of advanced turbine control features, including peak shaving and floating feedback as well as hull-based control using tuned mass dampers on the system. Overall, the results demonstrate measurable and consistent influences from the control and load-mitigation measures, thus confirming the usefulness as a validation data set. Peak shaving attenuates the response to wind turbulence at near-rated wind speed. Floating feedback reduces the load and platform pitch motion associated with the negative damping induced by blade pitch control. The tuned mass dampers also attenuate the system response near the targeted frequencies under suitable conditions. We also identify detrimental side effects of each load-mitigation measure.

17 WIND ENERGY↗