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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Seafloor Control on Sea Ice

The seafloor has a profound role in Arctic sea ice formation and seasonal evolution. Ocean bathymetry controls the distribution and mixing of warm and cold waters, which may originate from different sources, thereby dictating the pattern of sea ice on the ocean surface. Sea ice dynamics, forced by surface winds, are also guided by seafloor features in preferential directions. Here, satellite mapping of sea ice together with buoy measurements are used to reveal the bathymetric control on sea ice growth and dynamics. Bathymetric effects on sea ice formation are clearly observed in the conformation between sea ice patterns and bathymetric characteristics in the peripheral seas. Beyond local features, bathymetric control appears over extensive ice-prone regions across the Arctic Ocean. The large-scale conformation between bathymetry and patterns of different synoptic sea ice classes, including seasonal and perennial sea ice, is identified. An implication of the bathymetric influence is that the maximum extent of the total sea ice cover is relatively stable, as observed by scatterometer data in the decade of the 2000s, while the minimum ice extent has decreased drastically. Because of the geologic control, the sea ice cover can expand only as far as it reaches the seashore, the continental shelf break, or other pronounced bathymetric features in the peripheral seas. Since the seafloor does not change significantly for decades or centuries, sea ice patterns can be recurrent around certain bathymetric features, which, once identified, may help improve short-term forecast and seasonal outlook of the sea ice cover. Moreover, the seafloor can indirectly influence cloud cover by its control on sea ice distribution, which differentially modulates the latent heat flux through ice covered and open water areas.

Nghiem, S. V.↗
NASA NTRS1986

Regenerable non-venting thermal control subsystem for extravehicular activity

Routine and complex EVAs call for more effective heat rejection systems in order to maximize mission productivity; an optimum EVA mobility unit (EMU) thermal control subsystem must require no expendables and introduce no contaminants into the environment, while conforming to minimum size limits and allowing easy regeneration. Attention is presently given to two thermal control subsystems, one of which can be integrated with the existing Space Shuttle Orbiter EMU to provide a 3-hour nonventing heat rejection capability, while the other can furnish the entire heat rejection capability requirement for an 8-hour Space Station EVA.

Roebelen, George J.↗
NASA NTRS2014

An Evaluation of a Flight Deck Interval Management Algorithm Including Delayed Target Trajectories

NASA's first Air Traffic Management (ATM) Technology Demonstration (ATD-1) was created to facilitate the transition of mature air traffic management technologies from the laboratory to operational use. The technologies selected for demonstration are the Traffic Management Advisor with Terminal Metering (TMA-TM), which provides precise timebased scheduling in the terminal airspace; Controller Managed Spacing (CMS), which provides controllers with decision support tools enabling precise schedule conformance; and Interval Management (IM), which consists of flight deck automation that enables aircraft to achieve or maintain precise in-trail spacing. During high demand operations, TMA-TM may produce a schedule and corresponding aircraft trajectories that include delay to ensure that a particular aircraft will be properly spaced from other aircraft at each schedule waypoint. These delayed trajectories are not communicated to the automation onboard the aircraft, forcing the IM aircraft to use the published speeds to estimate the target aircraft's estimated time of arrival. As a result, the aircraft performing IM operations may follow an aircraft whose TMA-TM generated trajectories have substantial speed deviations from the speeds expected by the spacing algorithm. Previous spacing algorithms were not designed to handle this magnitude of uncertainty. A simulation was conducted to examine a modified spacing algorithm with the ability to follow aircraft flying delayed trajectories. The simulation investigated the use of the new spacing algorithm with various delayed speed profiles and wind conditions, as well as several other variables designed to simulate real-life variability. The results and conclusions of this study indicate that the new spacing algorithm generally exhibits good performance; however, some types of target aircraft speed profiles can cause the spacing algorithm to command less than optimal speed control behavior.

Swieringa, Kurt A.↗
NASA NTRS2016

System Performance of an Integrated Airborne Spacing Algorithm with Ground Automation

The National Aeronautics and Space Administration's (NASA's) first Air Traffic Management (ATM) Technology Demonstration (ATD-1) was created to facilitate the transition of mature ATM technologies from the laboratory to operational use. The technologies selected for demonstration are the Traffic Management Advisor with Terminal Metering (TMA-TM), which provides precise time-based scheduling in the Terminal airspace; Controller Managed Spacing (CMS), which provides controllers with decision support tools to enable precise schedule conformance; and Interval Management (IM), which consists of flight deck automation that enables aircraft to achieve or maintain precise spacing behind another aircraft. Recent simulations and IM algorithm development at NASA have focused on trajectory-based IM operations where aircraft equipped with IM avionics are expected to achieve a spacing goal, assigned by air traffic controllers, at the final approach fix. The recently published IM Minimum Operational Performance Standards describe five types of IM operations. This paper discusses the results and conclusions of a human-in-the-loop simulation that investigated three of those IM operations. The results presented in this paper focus on system performance and integration metrics. Overall, the IM operations conducted in this simulation integrated well with ground-based decisions support tools and certain types of IM operational were able to provide improved spacing precision at the final approach fix; however, some issues were identified that should be addressed prior to implementing IM procedures into real-world operations.

Swieringa, Kurt A.↗
NASA NTRS1992

Microgravity monitoring instrument development and application to vernier guidance, navigation, and vehicle control

The fact that a spacecraft traveling through the 'vacuum' of space conforms to the classical Keplerian ellipse has recently been disproven. It is now well known that such a vehicle is acted on by many external forces such as drag in the rarefied particle atmosphere, solar wind and particle impact. This paper discusses the development of sensors and sensor systems to measure these minute forces of acceleration/deceleration. Four systems will be discussed: a 10 exp -4 g system, a 10 exp -6 g system, a 10 exp -(6-8) g system and a 10 exp -9 g system. The design of each system will be explained along with the advantages/disadvantages of each. Various applications unique to each system will be discussed. Configurations, design schemes, test plans and calibration procedures, both in the ground laboratory and inflight, will be presented. The current design/development/operational status of each system will be examined and future plans discussed. Application to aerodynamic studies and vernier guidance, navigation, and vehicle control will also be examined.

Howell, Joseph J.↗
NASA NTRS2004

Theoretical Tools and Software for Modeling, Simulation and Control Design of Rocket Test Facilities

A rocket test stand and associated subsystems are complex devices whose operation requires that certain preparatory calculations be carried out before a test. In addition, real-time control calculations must be performed during the test, and further calculations are carried out after a test is completed. The latter may be required in order to evaluate if a particular test conformed to specifications. These calculations are used to set valve positions, pressure setpoints, control gains and other operating parameters so that a desired system behavior is obtained and the test can be successfully carried out. Currently, calculations are made in an ad-hoc fashion and involve trial-and-error procedures that may involve activating the system with the sole purpose of finding the correct parameter settings. The goals of this project are to develop mathematical models, control methodologies and associated simulation environments to provide a systematic and comprehensive prediction and real-time control capability. The models and controller designs are expected to be useful in two respects: 1) As a design tool, a model is the only way to determine the effects of design choices without building a prototype, which is, in the context of rocket test stands, impracticable; 2) As a prediction and tuning tool, a good model allows to set system parameters off-line, so that the expected system response conforms to specifications. This includes the setting of physical parameters, such as valve positions, and the configuration and tuning of any feedback controllers in the loop.

Richter, Hanz↗
NASA NTRS1995

Metrology: Measurement Assurance Program Guidelines

The 5300.4 series of NASA Handbooks for Reliability and Quality Assurance Programs have provisions for the establishment and utilization of a documented metrology system to control measurement processes and to provide objective evidence of quality conformance. The intent of these provisions is to assure consistency and conformance to specifications and tolerances of equipment, systems, materials, and processes procured and/or used by NASA, its international partners, contractors, subcontractors, and suppliers. This Measurement Assurance Program (MAP) guideline has the specific objectives to: (1) ensure the quality of measurements made within NASA programs; (2) establish realistic measurement process uncertainties; (3) maintain continuous control over the measurement processes; and (4) ensure measurement compatibility among NASA facilities. The publication addresses MAP methods as applied within and among NASA installations and serves as a guide to: control measurement processes at the local level (one facility); conduct measurement assurance programs in which a number of field installations are joint participants; and conduct measurement integrity (round robin) experiments in which a number of field installations participate to assess the overall quality of particular measurement processes at a point in time.

Eicke, W. G.↗
NASA NTRS2021

Frustration in Fuzzy Protein Complexes Leads to Interaction Versatility

Disordered proteins frequently serve as interaction hubs involving a constrained variety of partners. Complexes with different partners frequently exhibit distinct binding modes, involving regions that remain disordered in the bound state. While the conformational properties of disordered proteins are well-characterized in their free states, less is known about the molecular mechanisms by which specificity can be achieved not with one but with multiple partners. Using the energy landscape theory concept of protein frustration, we demonstrate that complexes of disordered proteins exhibit a high degree of local frustration, especially at the binding interface. These suboptimal interactions lead to the possibility of multiple bound substates, each displaying distinct frustration patterns, which are differently populated in complexes with different partners. These results explain how specificity of disordered proteins can be achieved without a single common bound conformation and how the conflict between different interactions can be used to control the binding to multiple partners.

Chemical specificity↗
NASA NTRS1984

Development of a thermal environment simulator for large test articles in a vacuum

The simulation of the thermal environment by varying the effective sink temperature about the test article was examined. The accuracy of this simulation depends upon the spectral emissivity/absorptivity, the number and size of the control zones, the temperature of each zone, and the geometry of the enclosure. A very large number of zones closely conforming to the surface of the test article quickly become prohibitive due to expense and control problems. A two zone low price enclosure does not have the fidelity required for thermal balance testing. The development of a simulator which for a reasonable cost, simulates the thermal balance environment for most large test articles in the future is described.

Storrs, H. B.↗
NASA NTRS1984

An analysis of Landsat-4 Thematic Mapper geometric properties

Landsat-4 Thematic Mapper data of Washington, DC, Harrisburg, PA, and Salton Sea, CA were analyzed to determine geometric integrity and conformity of the data to known earth surface geometry. Several tests were performed. Intraband correlation and interband registration were investigated. No problems were observed in the intraband analysis, and aside from indications of slight misregistration between bands of the primary versus bands of the secondary focal planes, interband registration was well within the specified tolerances. A substantial number of ground control points were found and used to check the images' conformity to the Space Oblique Mercator (SOM) projection of their respective areas. The means of the residual offsets, which included nonprocessing related measurement errors, were close to the one pixel level in the two scenes examined. The Harrisburg scene residual mean was 28.38 m (0.95 pixels) with a standard deviation of 19.82 m (0.66 pixels), while the mean and standard deviation for the Salton Sea scene were 40.46 (1.35 pixels) and 30.57 m (1.02 pixels), respectively. Overall, the data were judged to be a high geometric quality with errors close to those targeted by the TM sensor design specifications.

Walker, R. E.↗
NASA NTRS2001

En route Descent Advisor Concept for Efficient Arrival Metering Conformance

The En-route Descent Advisor (EDA) is a suite of decision support tool (DST) capabilities for en route sector subject to metering restrictions such as those generated by the Center TRACON Automation System (CTAS) Traffic Management Advisor. EDA assists controllers with high-density arrival metering by providing fuel-efficient metering-conformance advisories, integrated with conflict detection and resolution (CD&R) capabilities, to minimize deviations from the user s preferred trajectory. These DST capabilities will enable controllers to change their procedures from ones that are oriented towards sector management to procedures oriented towards trajectory management. Although adaptable to current procedures and airspace structure, EDA is intended as a tool for transitioning traffic from a Free Flight environment to an efficiently organized flow into terminal airspace. This paper describes the transition airspace problem and EDA concept, defines the key benefit mechanisms that will be enabled by EDA capabilities, and presents a traffic scenario to illustrate the use of the tool.

Green, Steven↗
NASA NTRS1986

Forebody vortex management for yaw control at high angles of attack

The yaw-control potential of deployable forebody strakes at angles of attack above the range of conventional rudder effectiveness has been investigated. The conformally-stored strakes when deployed force asymmetrical vortex shedding from the forebody, thereby generating a controlled yawing moment. The concept was explored through low-speed wind tunnel tests on a conical forebody in isolation and in a generic fighter configuration. Force and moment measurements on the complete model were supplemented with circumferential pressure and flow-visualization surveys on an isolated forebody, in order to gain insight into the vortex flow mechanisms resulting from forced asymmetrical separations and to quantify the obtainable yaw power at angles of attack to 80 deg. This preliminary, low-Reynolds-number study showed asymmetrically-deployed forebody strakes to have considerable yaw control potential, whose sensitivity to scale effects needs further investigation.

Rao, D. M.↗
NASA NTRS1991

Transformation of two and three-dimensional regions by elliptic systems

A reliable linear system is presented for grid generation in 2-D and 3-D. The method is robust in the sense that convergence is guaranteed but is not as reliable as other nonlinear elliptic methods in generating nonfolding grids. The construction of nonfolding grids depends on having reasonable approximations of cell aspect ratios and an appropriate distribution of grid points on the boundary of the region. Some guidelines are included on approximating the aspect ratios, but little help is offered on setting up the boundary grid other than to say that in 2-D the boundary correspondence should be close to that generated by a conformal mapping. It is assumed that the functions which control the grid distribution depend only on the computational variables and not on the physical variables. Whether this is actually the case depends on how the grid is constructed. In a dynamic adaptive procedure where the grid is constructed in the process of solving a fluid flow problem, the grid is usually updated at fixed iteration counts using the current value of the control function. Since the control function is not being updated during the iteration of the grid equations, the grid construction is a linear procedure. However, in the case of a static adaptive procedure where a trial solution is computed and used to construct an adaptive grid, the control functions may be recomputed at every step of the grid iteration.

Mastin, C. Wayne↗
NASA NTRS2004

Pilot in Command: An Illustration of Autonomous Flight Management

Several years of NASA research have produced the concept for air traffic management called "Distributed Air/Ground Traffic Management," a major operational advancement that should significantly increase the capacity of the National Airspace System. A key component, "Autonomous Flight Management," introduces a new class of aircraft operations in which pilots are authorized to freely maneuver and execute optimal trajectories independent from air traffic controllers. These aircraft operators would benefit from significant increases in flexibility to optimize all flight operations and from avoiding most of the delays associated with ground-controlled operations. Responsibilities for aircraft separation and arrival flow conformance are transferred to the flight deck, and the pilots use computerized decision-support tools to accomplish these tasks. A research prototype of these tools called the "Autonomous Operations Planner" is being developed at the NASA Langley Research Center. This 14-minute video illustrates Autonomous Flight Management from the airline pilot's perspective.

Wing, David J.↗
NASA NTRS2018

Modification of Radiator Pigments by Atomic Layer Deposition (ALD)

The optical and physical properties of spacecraft radiator coatings are dictated by orbital environmental conditions. For example, coatings must adequately dissipate charge buildup when orbital conditions, such as polar, geostationary or gravity neutral, result in surface charging. Current dissipation techniques include depositing a layer of ITO (indium tin oxide) on the radiator surface in a high temperature process. Other examples include the application of variable emittance coatings such as the use of VO2 to optimize radiator size, allowing for a decrease in heater power budget. The application of these enhanced coatings must be such that the properties in question are tailored to mission-specific requirements. Modification of these coatings can be accomplished during coating application preprocessing by using a deposition technique prevalent in the semiconductor micro processing industry called Atomic Layer Deposition (ALD). The preprocessing is rendered directly on the coating dry pigment before binding. ALD is a cost effective nano-manufacturing technique that allows for the conformal coating of substrates with atomic-level thickness control in a benign temperature and pressure environment. Through the introduction of paired precursor gases, thin films can be deposited on a myriad of substrates ranging from glass, polymers, aerogels, metals, powders, and other high aspect-ratio micro- and nano-structures. By providing atomic-level control, where single layers of atoms can be deposited, the fabrication of metal transparent films, precise nano-laminates, and coatings of nano-channels and pores is achievable. We have demonstrated a method for the ALD of In2O3 and ITO films on a variety of substrates from Si(100) wafers, glass slides, and on Z93P pigments (patent pending). The results indicate excellent growth of 4-22 nm thick films demonstrating an order of magnitude decrease in resistivity on the pigments.

ITO↗
NASA NTRS1973

Operations manual for the patient assist device

Quadriplegic patients and multiple amputee patients are almost totally dependent on nursing personnel for any activities or interests in which they participate. A patient assist device is reported which provides patient control over electrical devices in his environment. The patient operates three switches to acquire control over a desired electrical appliance. The type switches employed are chosen to conform to patient capabilities, even when such capabilities are as limited as eye or head movements. The switch operations are sensed and converted into command signals by the patient assist device to control ten electrical appliances simulataneously and independently.

Schrader, M. A.↗
NASA NTRS2017

Heater Validation for the NEXT-C Hollow Cathodes

Swaged cathode heaters whose design was successfully demonstrated under a prior flight project are to be provided by the NASA Glenn Research Center for the NEXT-C ion thruster being fabricated by Aerojet Rocketdyne. Extensive requalification activities were performed to validate process controls that had to be re-established or revised because systemic changes prevented reuse of the past approaches. A development batch of heaters was successfully fabricated based on the new process controls. Acceptance and cyclic life testing of multiple discharge and neutralizer sized heaters extracted from the development batch was initiated in August, 2016, with the last heater completing testing in April, 2017. Cyclic life testing results substantially exceeded the NEXT-C thruster requirement as well as all past experience for GRC fabricated units. The heaters demonstrated ultimate cyclic life capability of 19050 to 33500 cycles. A qualification batch of heaters is now being fabricated using the finalized process controls. A set of six heaters will be acceptance and cyclic tested to verify conformance to the behavior observed with the development heaters. The heaters for flight use will be then be provided to the contractor. This paper summarizes the fabrication process control activities and the acceptance and life testing of the development heater units.

hollow cathodes↗
NASA NTRS2004

System for Better Spacing of Airplanes En Route

An improved method of computing the spacing of airplanes en route, and software to implement the method, have been invented. The purpose of the invention is to help air-traffic controllers minimize those deviations of the airplanes from the trajectories preferred by their pilots that are needed to make the airplanes comply with miles-in-trail spacing requirements. The software is meant to be a modular component of the Center TRACON Automation System (CTAS) (TRACON signifies "terminal radar approach control"). The invention reduces controllers workloads and reduces fuel consumption by reducing the number of corrective clearances needed to achieve conformance with specified flow rates, without causing conflicts, while providing for more efficient distribution of spacing workload upstream and across air-traffic-control sectors.

Green, Steven↗