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Results for “flexibility potential”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Path planning for robotic truss assembly

A new Potential Fields approach to the robotic path planning problem is proposed and implemented. Our approach, which is based on one originally proposed by Munger, computes an incremental joint vector based upon attraction to a goal and repulsion from obstacles. By repetitively adding and computing these 'steps', it is hoped (but not guaranteed) that the robot will reach its goal. An attractive force exerted by the goal is found by solving for the the minimum norm solution to the linear Jacobian equation. A repulsive force between obstacles and the robot's links is used to avoid collisions. Its magnitude is inversely proportional to the distance. Together, these forces make the goal the global minimum potential point, but local minima can stop the robot from ever reaching that point. Our approach improves on a basic, potential field paradigm developed by Munger by using an active, adaptive field - what we will call a 'flexible' potential field. Active fields are stronger when objects move towards one another and weaker when they move apart. An adaptive field's strength is individually tailored to be just strong enough to avoid any collision. In addition to the local planner, a global planning algorithm helps the planner to avoid local field minima by providing subgoals. These subgoals are based on the obstacles which caused the local planner to fail. A best-first search algorithm A* is used for graph search.

Sanderson, Arthur C.↗
NASA NTRS1972

Ground-Commanded Television Assembly (GCTA)

A ground-commanded color television assembly (GCTA) was designed for use on lunar explorations associated with NASA manned Apollo missions. The camera system as seen on Apollo 15 provided television coverage in the vicinity of the lunar module (LM) landing site, and was mounted on the lunar roving vehicle (LRV) to provide color coverage of astronaut activity and lunar topography during traverses on the surface. Remote control of the camera from earth was accomplished through the existing real-time Apollo command links. The assembly is illustrated. The configuration satisfied all anticipated requirements of the Apollo 15 mission and was fully responsive to specifications. The technical approach was based on proven designs and offered maximum mission flexibility, potential growth, and capability to withstand environmental extremes encountered on the lunar surface.

Source record↗
NASA NTRS1974

Space Shuttle flutter as affected by wing-body aerodynamic interaction

In the NASA Langley Research Center 26-inch transonic blowdown wind-tunnel, flutter speeds were measured on 1/80-th scale semispan models of the orbiter wing, the complete Space Shuttle, and intermediate component combinations. Using the doublet lattice method combined with slender body theory to calculate unsteady aerodynamic forces, subsonic flutter speeds were computed for comparison. Aerodynamic interaction was found by test and analysis to raise the flutter speed in some configurations while lowering it in others. Although at Mach number less than 0.7, predicted speeds correlated to within 6% of those measured, rapid deterioration of the agreement occurred at higher subsonic Mach numbers, especially on the more complicated configurations. Additional analysis showed that aerodynamic forces arising from body flexibility potentially can have a large effect on flutter speed, but that the current shuttle design is not so affected.

Chipman, R. R.↗
NASA NTRS1975

EPA requirements and programs

The proposed ERTS-DCS system is designed to allow EPA the capability to evaluate, through demonstrable hardware, the effectiveness of automated data collection techniques. The total effectiveness of any system is dependent upon many factors which include equipment cost, installation, maintainability, logistic support, growth potential, flexibility and failure rate. This can best be accomplished by installing the system at an operational environmental control agency (CAMP station) to insure that valid data is being obtained and processed. Consequently, it is imperative that the equipment interface must not compromise the validity of the sensor data nor should the experimental system effect the present operations of the CAMP station. Since both the system which is presently in use and the automatic system would be in operation in parallel, conformation and comparison are readily obtained.

Koutsandreas, J. D.↗
NASA NTRS1984

Tunable mode and line selection by injection in a TEA CO2 laser

Tunable mode selection by injection in pulsed CO2 lasers is examined, and both analytical and numerical models are used to compute the required injection power for a variety of experimental cases. These are treated in two categories: mode selection at a desired frequency displacement from the center frequency of a transition line in a dispersive cavity and mode (and line) selection at the center frequency of a selected transition line in a nondispersive cavity. The results point out the potential flexibility of pulsed injection in providing wavelength tunable high-energy single-frequency pulses.

Menzies, R. T.↗
NASA NTRS2015

The Use of Field Programmable Gate Arrays (FPGA) in Small Satellite Communication Systems

This paper will describe the use of digital Field Programmable Gate Arrays (FPGA) to contribute to advancing the state-of-the-art in software defined radio (SDR) transponder design for the emerging SmallSat and CubeSat industry and to provide advances for NASA as described in the TAO5 Communication and Navigation Roadmap (Ref 4). The use of software defined radios (SDR) has been around for a long time. A typical implementation of the SDR is to use a processor and write software to implement all the functions of filtering, carrier recovery, error correction, framing etc. Even with modern high speed and low power digital signal processors, high speed memories, and efficient coding, the compute intensive nature of digital filters, error correcting and other algorithms is too much for modern processors to get efficient use of the available bandwidth to the ground. By using FPGAs, these compute intensive tasks can be done in parallel, pipelined fashion and more efficiently use every clock cycle to significantly increase throughput while maintaining low power. These methods will implement digital radios with significant data rates in the X and Ka bands. Using these state-of-the-art technologies, unprecedented uplink and downlink capabilities can be achieved in a 1/2 U sized telemetry system. Additionally, modern FPGAs have embedded processing systems, such as ARM cores, integrated inside the FPGA allowing mundane tasks such as parameter commanding to occur easily and flexibly. Potential partners include other NASA centers, industry and the DOD. These assets are associated with small satellite demonstration flights, LEO and deep space applications. MSFC currently has an SDR transponder test-bed using Hardware-in-the-Loop techniques to evaluate and improve SDR technologies.

Varnavas, Kosta↗
NASA NTRS1993

Unsteady transonic potential flow over a flexible fuselage

A flexible fuselage capability has been developed and implemented within version 1.2 of the CAP-TSD code. The capability required adding time dependent terms to the fuselage surface boundary conditions and the fuselage surface pressure coefficient. The new capability will allow modeling the effect of a flexible fuselage on the aeroelastic stability of complex configurations. To assess the flexible fuselage capability several steady and unsteady calculations have been performed for slender fuselages with circular cross-sections. Steady surface pressures are compared with experiment at transonic flight conditions. Unsteady cross-sectional lift is compared with other analytical results at a low subsonic speed and a transonic case has been computed. The comparisons demonstrate the accuracy of the flexible fuselage modifications.

Gibbons, Michael D.↗
NASA NTRS1981

Contextual classification on a CDC Flexible Processor system

A potential hardware organization for the Flexible Processor Array is presented. An algorithm that implements a contextual classifier for remote sensing data analysis is given, along with uniprocessor classification algorithms. The Flexible Processor algorithm is provided, as are simulated timings for contextual classifiers run on the Flexible Processor Array and another system. The timings are analyzed for context neighborhoods of sizes three and nine.

Smith, B. W.↗
NASA NTRSDate not supplied

Electrical Discharge Machining of Additively Manufactured Superalloys Containing Oxide Dispersions

Superalloys can be strengthened by oxide dispersions to potentially improve their mechanical properties at high temperatures. Additive manufacturing has opened new paths for introducing oxide particles into superalloys with increased processing flexibility, to potentially provide oxide dispersion strengthening. Numerically controlled electrical discharge machining (EDM) has often been used as a machining process for initial sectioning, detailed roughing, and even finishing operations of conventional superalloys. The objective of this study was to examine how additively manufactured superalloys containing oxide dispersions respond when sectioned using EDM. Consistent sections of several superalloys, two containing an oxide dispersion, were sliced using a typical EDM machine with standard brass wire and a typical roughing condition set. Roughness, microstructure, and residual stress at the EDM surfaces were compared for the varied superalloys.

superalloys↗
NASA NTRS2008

Ares-I-X Stability and Control Flight Test: Analysis and Plans

The flight test of the Ares I-X vehicle provides a unique opportunity to reduce risk of the design of the Ares I vehicle and test out design, math modeling, and analysis methods. One of the key features of the Ares I design is the significant static aerodynamic instability coupled with the relatively flexible vehicle - potentially resulting in a challenging controls problem to provide adequate flight path performance while also providing adequate structural mode damping and preventing adverse control coupling to the flexible structural modes. Another challenge is to obtain enough data from the single flight to be able to conduct analysis showing the effectiveness of the controls solutions and have data to inform design decisions for Ares I. This paper will outline the modeling approaches and control system design to conduct this flight test, and also the system identification techniques developed to extract key information such as control system performance (gain/phase margins, for example), structural dynamics responses, and aerodynamic model estimations.

Brandon, Jay M.↗
NASA NTRS1983

An assessment of advanced technology for industrial cogeneration

The potential of advanced fuel utilization and energy conversion technologies to enhance the outlook for the increased use of industrial cogeneration was assessed. The attributes of advanced cogeneration systems that served as the basis for the assessment included their fuel flexibility and potential for low emissions, efficiency of fuel or energy utilization, capital equipment and operating costs, and state of technological development. Over thirty advanced cogeneration systems were evaluated. These cogeneration system options were based on Rankine cycle, gas turbine engine, reciprocating engine, Stirling engine, and fuel cell energy conversion systems. The alternatives for fuel utilization included atmospheric and pressurized fluidized bed combustors, gasifiers, conventional combustion systems, alternative energy sources, and waste heat recovery. Two advanced cogeneration systems with mid-term (3 to 5 year) potential were found to offer low emissions, multi-fuel capability, and a low cost of producing electricity. Both advanced cogeneration systems are based on conventional gas turbine engine/exhaust heat recovery technology; however, they incorporate advanced fuel utilization systems.

Moore, N.↗
NASA NTRS1972

Development of STOLAND, a versatile navigation, guidance and control system

STOLAND has been developed to perform navigation, guidance, control, and flight management experiments in advanced V/STOL aircraft. The experiments have broad requirements and have dictated that STOLAND be capable of providing performance that would be realistic and equivalent to a wide range of current and future avionics systems. An integrated digital concept using modern avionics components was selected as the simplest approach to maximizing versatility and growth potential. Unique flexibility has been obtained by use of a single, general-purpose digital computer for all navigation, guidance, control, and displays computation.

Young, L. S.↗
NASA NTRS1972

Development of STOLAND, a versatile navigation, guidance and control system.

STOLAND has been developed to perform navigation, guidance, control, and flight management experiments in advanced V/STOL aircraft. An integrated digital concept using modern avionics components was selected as the simplest approach to maximizing versatility and growth potential. Unique flexibility has been obtained by use of a single, general-purpose digital computer for all navigation, guidance, control, and displays computation. Modularity of the software insures easy change of experiments. The general-purpose computer is integrated with flexible pilot controls and with both electromechanical and CRT displays for maximum cockpit versatility. A complex hierarchy of control modes with safety monitors and interlocks has been provided.

Hansen, Q. M.↗
NASA NTRS1972

Tracking and data relay satellite system configuration and tradeoff study, part 1. Volume 1: Summary volume

Study efforts directed at defining all TDRS system elements are summarized. Emphasis was placed on synthesis of a space segment design optimized to support low and medium data rate user spacecraft and launched with Delta 2914. A preliminary design of the satellite was developed and conceptual designs of the user spacecraft terminal and TDRS ground station were defined. As a result of the analyses and design effort it was determined that (1) a 3-axis-stabilized tracking and data relay satellite launched on a Delta 2914 provides telecommunications services considerably in excess of that required by the study statement; and (2) the design concept supports the needs of the space shuttle and has sufficient growth potential and flexibility to provide telecommunications services to high data rate users. Recommendations for further study are included.

Source record↗
NASA NTRS1978

Design consideration for a nuclear electric propulsion system

A study is currently underway to design a nuclear electric propulsion vehicle capable of performing detailed exploration of the outer-planets. Primary emphasis is on the power subsystem. Secondary emphasis includes integration into a spacecraft, and integration with the thrust subsystem and science package or payload. The results of several design iterations indicate an all-heat-pipe system offers greater reliability, elimination of many technology development areas and a specific weight of under 20 kg/kWe at the 400 kWe power level. The system is compatible with a single Shuttle launch and provides greater safety than could be obtained with designs using pumped liquid metal cooling. Two configurations, one with the reactor and power conversion forward on the spacecraft with the ion engines aft and the other with reactor, power conversion and ion engines aft were selected as dual baseline designs based on minimum weight, minimum required technology development and maximum growth potential and flexibility.

Phillips, W. M.↗
NASA NTRS1989

MSAT signalling and network management architectures

Spar Aerospace has been active in the design and definition of Mobile Satellite Systems since the mid 1970's. In work sponsored by the Canadian Department of Communications, various payload configurations have evolved. In addressing the payload configuration, the requirements of the mobile user, the service provider and the satellite operator have always been the most important consideration. The current Spar 11 beam satellite design is reviewed, and its capabilities to provide flexibility and potential for network growth within the WARC87 allocations are explored. To enable the full capabilities of the payload to be realized, a large amount of ground based Switching and Network Management infrastructure will be required, when space segment becomes available. Early indications were that a single custom designed Demand Assignment Multiple Access (DAMA) switch should be implemented to provide efficient use of the space segment. As MSAT has evolved into a multiple service concept, supporting many service providers, this architecture should be reviewed. Some possible signalling and Network Management solutions are explored.

Garland, Peter↗
NASA NTRS1993

A theory of nonlocal mixing-length convection. I - The moment formalism

A flexible and potentially powerful theory of convection, based on the mixing length picture, is developed to make unbiased self-consistent predictions about overshooting and other complicated phenomena in convection. The basic formalism is set up, and the method's power is demonstrated by showing that a simplified version of the theory reproduces all the standard results of local convection. The second-order equations of the theory are considered in the limit of a steady state and vanishing third moments, and it is shown that they reproduce all the standard results of local mixing-length convection. There is a particular value of the superadiabatic gradient, below which the only possible steady state of a fluid is nonconvecting. Above this critical value, a fluid is convectively unstable. Two distinct regimes of convection, which are identified as efficient and inefficient convection, are determined.

Grossman, Scott A.↗
NASA NTRS2000

Compact Hyperspectral Mapper for Environmental Remote Sensing Applications (CHyMERA) End-of-phase Data Review Package

CHYMERA is an Instrument Incubator concept to design, build, and test an instrument that will reduce size, mass, and cost and increase science potential and flexibility for future atmospheric remote sensing missions within the focus of NASA's Earth Science Enterprise (ESE). The primary effort of the development plan will be on high spatial resolution ozone, N02, S02, aerosol, and cloud measurements, but it is hoped that the techniques developed will prove useful for other measurements as well. The core design will involve a high performance, wide field-of-view (FOV) front end telescope which will illuminate a filter/focal plane array (FFPA) package. The use of a non-dispersive optical configuration will reduce size, mass and complexity. The wide FOV optics will permit short duration global coverage (1-2 days) without the need for a scanner.

Janz, Scott J.↗