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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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Film deposition of cermet resistors on same chip with metal nitride oxide silicon field effect transistors permits protection of contamination sensitive active devices from contaminants produced in cermet deposition and definition processes. Additional advantages include lower cost, greater reliability, and space savings.
The improvement and extension of the capabilities of the Environmental Research Institute of Michigan processing facility in handling multispectral data are discussed. Improvements consisted of implementing hardware modifications which permitted more rapid access to the recorded data through improved numbering and indexing of such data. In addition, techniques are discussed for handling data from sources other than the ERIM M-5 and M-7 scanner systems.
A survey on the disturbance caused by aircraft noise was evaluated. The use of a questionnaire as a scale rather than considering isolated question responses is seen as more objective. A standardized structure for questionnaires of the opinion surveys on aircraft noise, which includes a set of questions permitting the analysis of the disturbance caused by different daily activities is recommended. The statistical processing of the answers, to achieve the most reliable evaluation of disturbance felt are discussed.
An advisory report to be used by NASA in developing a program plan for a Pilot Land Data System (PLDS) was developed. The purpose of the PLDS is to improve the ability of NASA and NASA sponsored researchers to conduct land-related research. The goal of the planning workshops was to provide and coordinate planning and concept development between the land related science and computer science disciplines, to discuss the architecture of the PLDs, requirements for information science technology, and system evaluation. The findings and recommendations of the Working Group are presented. The pilot program establishes a limited scale distributed information system to explore scientific, technical, and management approaches to satisfying the needs of the land science community. The PLDS paves the way for a land data system to improve data access, processing, transfer, and analysis, which land sciences information synthesis occurs on a scale not previously permitted because of limits to data assembly and access.
The Shuttle Imaging Radar-B (SIR-B) will be the third in a series of spaceborne SAR experiments which began with the 1978 launch of Seasat and continued with the 1981 launch of Seasat and continued with the 1981 launch of SIR-A. Like Seasat and SIR-A, SIR-B will operate at L-band and be horizontally polarized. However, SIR-B will allow digitally processed imagery to be acquired at selectable look angles between 15 and 60 deg, thereby permitting for the first time quantitative and analytical studies of the geometric variables associated with a radar image. These geometric variables include look angle and look direction which have never been studied with previous fixed parameter radar systems.
The objectives were to: (1) develop an objective analysis technique that will maximize the information content of data available from diverse sources, with particular emphasis on the incorporation of observations from satellites with those from more traditional immersion techniques; and (2) to develop a diagnosis of the state of the synoptic scale atmosphere on a much finer scale over a much broader region than is presently possible to permit studies of the interactions and energy transfers between global, synoptic and regional scale atmospheric processes. The variational objective analysis model consists of the two horizontal momentum equations, the hydrostatic equation, and the integrated continuity equation for a dry hydrostatic atmosphere. Preliminary tests of the model with the SESMAE I data set are underway for 12 GMT 10 April 1979. At this stage of purpose of the analysis is not the diagnosis of atmospheric structures but rather the validation of the model. Model runs for rawinsonde data and with the precision modulus weights set to force most of the adjustment of the wind field to the mass field have produced 90 to 95 percent reductions in the imbalance of the initial data after only 4-cycles through the Euler-Lagrange equations. Sensitivity tests for linear stability of the 11 Euler-Lagrange equations that make up the VASP Model 1 indicate that there will be a lower limit to the scales of motion that can be resolved by this method. Linear stability criteria are violated where there is large horizontal wind shear near the upper tropospheric jet.
Composite material systems are currently good candidates for aerospace structures, primarily for the design flexibility they offer, i.e., it is possible to tailor the material and manufacturing approach to the application. A working definition of elastic or structural tailoring is the use of structural concept, fiber orientation, ply stacking sequence, and a blend of materials to achieve specific performance goals. In the design process, choices of materials and dimensions are made which produce specific response characteristics, and which permit the selected goals to be achieved. Common choices for tailoring goals are preventing instabilities or vibration resonances or enhancing damage tolerance. An essential, enabling factor in the design of tailored composite structures is structural modeling that accurately, but simply, characterizes response. The objective of this paper is to present a new multicell beam model for composite rotor blades and to validate predictions based on the new model by comparison with a finite element simulation in three benchmark static load cases.
An inconsistency is examined in generic top-down design methods and standards employed in the implementation of reliable software. Many design approaches adopt top-down ordering when defining the structure, interfaces, and processing of a system. However, strict adherence to a top-down sequencing does not permit accurate description of a system's error handling functions. The design of the system response to errors is becoming critical as the reliability requirements of systems increase. How top-down methods such as object oriented design and structured design do not adequately address the issues of error handling is described, and it is suggested using a bottom-up substep within these methods to eliminate the problem.
A NASTRAN bulk dataset preprocessor was developed to facilitate the integration of filamentary composite laminate properties into composite structural resizing for stiffness requirements. The NASCOMP system generates delta stiffness and delta mass matrices for input to the flutter derivative program. The flutter baseline analysis, derivative calculations, and stiffness and mass matrix updates are controlled by engineer defined processes under an operating system called CBUS. A multi-layered design variable grid system permits high fidelity resizing without excessive computer cost. The NASCOMP system uses ply layup drawings for basic input. The aeroelastic resizing for stiffness capability was used during an actual design exercise.
The presence of particles in the Martian atmosphere increases the rate of erosion of the heat shield during the entry phase of the MESUR mission. Preliminary analysis has shown that under certain conditions particles will penetrate the bow shock of the entry vehicle, impact and erode the heat shield, above the anticipated rate from the ablation process. Knowledge of the distribution, sizes, and composition of particles suspended in the atmosphere will permit the estimation of the heat shield recession both for a nominal Mars atmosphere and in dust storm conditions. On the surface of Mars, sand and dust can effect the operations and design of the science instruments (i.e., imaging) and lander subsystems (i.e., solar arrays). Distribution and deposition of sand and dust on the planet's surface will dictate the feasibility of using solar arrays as a power source for the lander. Furthermore, the potential abrasive nature of blowing particles must be understood in order to properly select suitable materials for lander structure and any components exposed to the environment. The selection of lander material may also be dictated by corrosive and chemically active properties of particles at a potential landing site. Some key interests concerning sand and dust on the surface and in the atmosphere are summarized in a number of questions that are included.
A method is described for measuring the dynamic stability derivatives of a model airplane in a wind tunnel. The characteristic features of this system are that single-degree-of-freedom oscillations were used to obtain combinations of rolling, yawing and pitching motions; that the oscillations were excited and controlled by velocity feedback which permitted operation under conditions unfavorable for more conventional types of oscillatory testing; and that data processing was greatly simplified by using analog computer elements in the strain-gage circuitry. A small number of experimental data are included to illustrate the general scope of results obtainable with this system.
Per- and polyfluoroalkyl substances (PFAS) have been found in investigative derived waste (IDW) generated from groundwater sampling and remediation activities conducted at Kennedy Space Center (KSC), Florida. PFAS are exceptionally strong compounds because of carbon-fluorine bonds resulting in resistance to degradation, low chemical reactivity, compound stability, and persistence in the environment. The regulatory status of PFAS is very dynamic. PFAS is not considered a hazardous waste and has no federal or state (Florida) cleanup requirements at this time. Due to the current and unknown future of the regulatory and treatment landscape, non-hazardous IDW, based upon site volatile organic compounds (VOCs) regulated under Title 40 of Federal Regulations part 261, containing PFAS is not being processed for off-site waste disposal under KSC’s Resource Conservation and Recovery Act permit as a proactive precaution. Long-term storage of aqueous IDW in the meantime was determined to be inadequate due to the potential for spills and/or leaks. A very limited number treatment methods are available at this time. To date, granular activated carbon (GAC) and ion exchange technologies have been found to be some of the most consistent treatment options for removing PFAS from aqueous media. Therefore, a pilot study using GAC was developed at KSC to determine the feasibility of treating non-hazardous IDW containing PFAS to reduce the total volume of PFAS waste and minimize the risk of leaks or spills while storing the waste until complete PFAS-destructive treatment options are more readily available. NASA wanted the pilot test to be able to demonstrate the ability to completely remove 18 PFAS compounds and the site VOCs to below the state of Florida groundwater cleanup target levels (GCTLs).
Report on a new and general technique for simulating atmospheric turbulence-like random processes which are statistically homogeneous along the horizontal and nonhomogeneous along the vertical. This technique is general in the sense that it can be used for a broad class of similar problems. Like the other presently available schemes, the techniques presented are based on the Dryden hypothesis and Taylor's frozen eddy hypothesis; however, they go a step further by utilizing certain self-similarity properties of the Dryden spectral density function which permits the development of height invariant filters. These filters are in turn used to generate vertically homogeneous (statistically) random processes from which turbulence at any specified level in the boundary layer can be simulated, thus facilitating the simulation of a nonstationary turbulence process along the flight path of an aircraft during take-off or landing.
Observational evidence suggests that stars greater than 100 M(solar) exist in the Galaxy and Large Magellanic Cloud (LMC), however classical star formation theory predicts stellar mass limits of only approx. 60 M(solar). A protostellar accretion flow consists of inflowing gas and dust. Grains are destroyed as they are near the central protostar creating a dust shell or cocoon. Radiation pressure acting on the grain can halt the inflow of material thereby limiting the amount of mass accumulated by the protostar. We first consider rather general constraints on the initial grain to gas ratio and mass accretion rates that permit inflow. We further constrain these results by constructing a numerical model. Radiative deceleration of grains and grain destruction processes are explicitly accounted for in an iterative solution of the radiation-hydrodynamic equations. Findings seem to suggest that star formation by spherical accretion requires rather extreme preconditioning of the grain and gas environment.
A plurality of redundant channels in a system each contain a global image of all the configuration data bases in each of the channels in the system. Each global image is updated periodically from each of the other channels via cross channel data links. The global images of the local configuration data bases in each channel are separately symmetrized using a voting process to generate a system signal configuration data base which is not written into by any other routine and is available for indicating the status of the system within each channel. Equalization may be imposed on a suspect signal and a number of chances for that signal to heal itself are provided before excluding it from future votes. Reconfiguration is accomplished upon detecting a channel which is deemed invalid. A reset function is provided which permits an externally generated reset signal to permit a previously excluded channel to be reincluded within the system. The updating of global images and/or the symmetrization process may be accomplished at substantially the same time within a synchronized time frame common to all channels.
A system for sealing vacuum baked hybrids in a dry inert atmosphere using an overlapping spot resistance weld is described. A unique electrode configuration and fixturing that permits sealing of large and irregularly shaped gold plated Kovar packages to the hermeticity requirements of MIL-STD-883 was discussed. Metallurgical considerations and comparisons to laser sealing were made. Problems encountered during the development and optimization of the process were highlighted. Solutions to plating, fixturing, warpage, weld splatter and cracked bead problems are presented.
PIP-II at Fermilab features a brand-new, 800 MeV leading-edge Linear Accelerator (Linac) that will enable the Fermilab complex to deliver more than a megawatt of beam power to the Long Base-line Neutrino Facility (LBNF), requiring a robust Machine Protection System (MPS) to prevent beam-induced damage to delicate cryomodules and vacuum components. Signals in various accelerator components, in both analog and digital format, are collected and processed to assest the operating conditions of the accelerator. In the situation a potential damage is foreseen, the beam permit signal will be drop. A critical element of this system is the fast Analog Machine Protection System, a high-bandwidth platform designed for real-time beam loss monitoring. The system utilizes a modular, FPGA-based architecture to digitize signals from beam-sensing devices, such as AC Current Transformers (ACCTs), non-invasive Ring Pickups (RPUs) and beam scrapers. To eliminate both high frequency as well as 60 Hz noise that might be picked up in the industrial environment, data processing schemes beyond regular digital filtering are planned and implemented.
Poly(lactic acid) (PLA) is the most widely explored biodegradable alternative for polystyrene; however, its low toughness and glass transition temperature may limit its wider adoption as a sustainable replacement. To improve its material and thermal properties, PLA can be chemically or physically combined with other polymers, like poly(methyl methacrylate) (PMMA), though the incorporation of vinyl‐based polymer components complicates chemical recycling and reduces the sustainability of the material. Here, in this study, we synthesized polymethacrylate‐PLA comb copolymers designed to be thermally deconstructed. Our design strategically extends current polymer deconstruction methodologies to more complex macromolecular systems. Thermally labile units within the polymethacrylate backbone permitted depolymerization that was concurrent with PLA side chain degradation during heating. This dual degradation‐depolymerization process enhances the overall sustainability of lactide/vinyl‐based copolymers and demonstrates the synergistic potential of integrating multiple deconstruction pathways into a single system. This report elaborates on the design of advanced, degradable copolymers, contributing to the further development of sustainable polymer materials.