silkski/ENERAD huggingface dataset:
The dynamics of a class of TVD schemes for model hyperbolic and parabolic equations is studied numerically using a highly parallel supercomputer ( CM-5 ) . The objective is to utilize the highly parallel property of the CM-5 to reveal the reliable time step and entropy parameter ranges , and the degree of compressible flux limiters to avoid slow convergence and the production of nonphysical numerical solutions . We choose to study the nonlinear stability property of TVD schemes numerically since it is otherwise not amenable analytically .
The microstructural evolution following metal cutting was investigated within metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece . The initial microstructure of the parent material ( PM ) was composed of a bi - modal microstructure with coarse prior beta grains and equiaxed primary alpha located at the boundaries . After metal cutting , the microstructure of the metal chips showed coarsening of the equiaxed primary alpha grains and beta lamellar . These metallographic findings suggest that the metal chips experienced high temperatures which remained below the beta transus temperature .
We will discuss photochemical properties of Titan 's organic molecules in the condensed phase as solid aerosols or surface material , from small linear polyyenes ( polyacetylenes and polycyanoacetylenes ) such as C2H2 , C4N2 , HC5N , etc . In particular we will focus on photochemistry caused by longer wavelength UV - VIS photons ( greater than 250 nm ) photons that make it through Titan 's atmosphere to the haze region ( approximately 100 km ) and on to the surface of Titan .
This viewgraph presentation reviews the use of a Robust Servo Linear Quadratic Regulator ( LQR ) and a Radial Basis Function ( RBF ) Neural Network in reconfigurable flight control designs in adaptation to a aircraft part failure . The method uses a robust LQR servomechanism design with model Reference adaptive control , and RBF neural networks . During the failure the LQR servomechanism behaved well , and using the neural networks improved the tracking .
This paper evaluates the ability of progressive damage analysis ( PDA ) finite element ( FE ) models to predict transverse matrix cracks in unidirectional composites . The results of the analyses are compared to closed - form linear elastic fracture mechanics ( LEFM ) solutions . Matrix cracks in fiber - reinforced composite materials subjected to mode I and mode II loading are studied using continuum damage mechanics and zero - thickness cohesive zone modeling approaches . The FE models used in this study are built parametrically so as to investigate several model input variables and the limits associated with matching the upper - bound LEFM solutions . Specifically , the sensitivity of the PDA FE model results to changes in strength and element size are investigated .
In developing a flexible body spacecraft simulation for the Launch Abort System of the Orion vehicle , when a rapid mass depletion takes place , the dynamics problem with time varying eigenmodes had to be addressed . Three different techniques were implemented , with different trade - offs made between performance and fidelity . A number of technical issues had to be solved in the process . This paper covers the background of the variable mass flexibility problem , the three approaches to simulating it , and the technical issues that were solved in formulating and implementing them .
A viewgraph presentation outlines the scientific payload , expected launch date and tasks , and an image of the Mars Surveyor 2001 Lander components . The Lander 's battery specifications are given . The program objectives for the Li - ion cells for the Lander are listed , and results performance evaluation and cycle life performance tests are outlined for different temperatures . Cell charge characteristics are described , and test data is presented for charge capacity at varying temperatures . Capacity retention and storage characteristics tests are described and results are shown .
The successful development of extremely low background sample cells for x - ray scattering studies has enabled experiments designed to elucidate some of the fundamental physical interactions involved in macromolecular folding . Microfabrication techniques were used to fabricate low volume ( 50 micro - liter ) sample cells with silicon nitride membranes ( sub micron in thickness ) as x - ray windows . Scientifically , these studies focus on the interaction of negatively charged nucleic acid systems , RNA and DNA , with their surrounding ( positively charged ) ion atmospheres . Understanding the structure of the ion atmosphere and its influence on the shape / conformation of the macromolecule will help reveal the underlying physical forces employed by nature in the self - assembly of these important molecules .
The detector assembly for the Mid Infrared Instrument ( MIRI ) of the James Webb Space Telescope ( JWST ) is mechanically supported in the Focal Plane Module ( FPM ) Assembly with an efficient hexapod design . The kinematic mount design allows for precision adjustment of the detector boresight to assembly alignment fiducials and maintains optical alignment requirements during flight conditions of launch and cryogenic operations below 7 Kelvin . This kinematic mounting technique is able to be implemented in a variety of optical - mechanical designs and is capable of micron level adjustment control and stability over wide dynamic and temperature ranges .
The end of the Space Shuttle program brought new challenges as well as new opportunities to the John F. Kennedy Space Center . The challenge is to engineer a more flexible Spaceport to be capable of supporting manufacturing , assembly , testing , processing and launch operations for multiple spacecrafts and launch vehicle configurations . The new spaceport must support multiple commercial as well as government entities while leveraging existing infrastructure to the greatest extent possible . This paper addresses key engineering challenges during Spaceport design and development and will look at possible engineering solutions while considering reusability of legacy systems and infrastructure adaptability with emphasis on flexibility and reduction of operating cost .
Fault tolerance and safety verification of control systems are essential for the success of autonomous robotic systems . A control architecture called Mission Data System ( MDS ) , developed at the Jet Propulsion Laboratory , takes a goal - based control approach . In this paper , a method for converting goal network control programs into linear hybrid systems is developed . The linear hybrid system can then be verified for safety in the presence of failures using existing symbolic model checkers . An example task is simulated in MDS and successfully verified using HyTech , a symbolic model checking software for linear hybrid systems .
In the two decades since Iijima 's report on carbon nanotubes ( CNT ) , there has been great interest in realizing the benefits of mechanical properties observed at the nanoscale in large - scale structures . The weight savings possible due to dramatic improvements in mechanical properties relative to state - of - the - art material systems can be game changing for applications like aerospace vehicles . While there has been significant progress in commercial production of CNTs , major aerospace applications that take advantage of properties offered by this material have yet to be realized . This paper provides a perspective on the technical challenges and barriers for insertion of CNTs as an emerging material technology in aerospace applications and proposes approaches that may reduce the typical timeframe for technology maturation and insertion into aerospace structures .
To successfully implement the behavioral aspects required to select and screen for long - duration missions on the International Space Station and for Artemis Program lunar missions , a multi - phase process combining best practice elements from the fields of industrial - organizational psychology , operational psychology , aerospace psychology and aerospace psychiatry , are needed . Furthermore , this process should preferably be implemented by professionals with extensive experience in human spaceflight operations .
Electronic structure calculations can provide accurate spectroscopic data ( such as molecular structures ) vibrational frequencies , binding energies , etc . ) that have been very useful in explaining trends in experimental data and in identifying incorrect experimental measurements . In addition , ab initio calculations . have given considerable insight into the many interactions that make the chemistry of transition metal systems so diverse . In this review we focus on cases where calculations and experiment have been used to solve interesting chemical problems involving metal ions . The examples include cases where theory was used to differentiate between disparate experimental values and cases where theory was used to explain unexpected experimental results .
The objective of this study is to understand the process of gas phase agglomeration leading to superagglomerates and a gel - like structure for microgravity ( 0 - g ) silane and acetylene flames . Ultimately one would apply this understanding to predicting flame conditions that could lead to the gas phase production of an aero - gel . The approach is to burn acetylene and silane and to analyze the evolution of the soot and silica agglomerates . Acetylene is chosen because it has one of the highest soot volume fractions and there is evidence of super agglomerates being formed in laminar acetylene flames . Silane has the advantage that silica particles are the major combustion product resulting in a particle volume fraction a factor of ten greater than that for a carbonaceous smoke .
Advanced aerospace systems occasionally require the use of very brittle materials such as sapphire and ultra - high temperature ceramics . Although great progress has been made in the development of methods and standards for machining , testing and design of component from these materials , additional development and dissemination of standard practices is needed . ASTM Committee C28 on Advanced Ceramics and ISO TC 206 have taken a lead role in the standardization of testing for ceramics , and recent efforts and needs in standards development by Committee C28 on Advanced Ceramics will be summarized . In some cases , the engineers , etc . involved are unaware of the latest developments , and traditional approaches applicable to other material systems are applied . Two examples of flight hardware failures that might have been prevented via education and standardization will be presented .
Many students are not even aware of the many activities related to the US Space Program . The intent of this presentation is to introduce students to the world of space exploration and encourage them to pursue math , science , and engineering careers . If this is not their particular interest , I want to encourage them to pursue their dream .
The Dawn spacecraft orbited the asteroid Vesta from July 16 , 2011 to September 5 , 2012 , successfully accomplishing the four planned science orbits and two planned rotational characterization orbits . The lowest - altitude science orbit lasted four months , with 20 planned orbit maintenance maneuvers . Navigation results from Vesta demonstrate that the navigation plan was sufficient to achieve orbit delivery accuracy requirements . This paper compares the flown Dawn trajectory against the planned trajectory and expected maneuver dispersions . Understanding the effectiveness of the Vesta maneuver design plan is a key component of planning for operations at Ceres , the next destination for the Dawn mission .
The nickel electrode is the specific energy limiting component in battery systems such as nickel - hydrogen , nickel - metal hydride and nickel - zinc . Lightweight , high energy density nickel electrodes have been developed which deliver in excess of 180 mAh / g at the one - hour discharge rate . These electrodes are based on a highly porous , nickel micro - fiber ( less than 10 micron diameter ) substrate , electrochemically impregnated with nickel - hydroxide active material . Electrodes are being tested both as a flooded half - cell and in full nickel - hydrogen and nickel - metal hydride cells . The electrode technology developed is applicable to commercial nickel - based batteries for applications such as electric vehicles , cellular telephones and laptop computers and for low - cost , high energy density military and aerospace applications .
This viewgraph presentation reviews NASA Dryden 's role in the UAVSAR Program . The primary objective of the UAVSAR Project is to develop a miniaturized polarimetric L - band synthetic aperture radar ( SAR ) for use on an unmanned aerial vehicle ( UAV ) or minimally piloted vehicle . Dryden 's work in developing the Platform Precision Autopilot ( PPA ) capability is described in this presentation . The goal for the development is that the PPA shall fly the G - III within a 10 m ( 32.8 ft ) diameter tube for at least 90 % of each data take in conditions of calm to light atmospheric disturbances , as defined . The G - III aircraft is descrbed , the test plan is outlined , and the initial test results are reviewed .
An experimental forward - swept fan encountered flutter at part - speed conditions during wind tunnel testing . A new propulsion aeroelasticity code , based on a computational fluid dynamics ( CFD ) approach , was used to model the aeroelastic behavior of this fan . This threedimensional code models the unsteady flowfield due to blade vibrations using a harmonic balance method to solve the Navier - Stokes equations . This paper describes the flutter calculations and compares the results to experimental measurements and previous results from a time - accurate propulsion aeroelasticity code .
This study first examined the possibility of placing NASA CD 's in the Spacelink Public Electronic Library ( SPEL ) . The goal of this task was to place these materials on the Internet . The second part of the study addressed the possibility of using CD 's as storage for portions of SPEL . These files would also be on the Internet and available to the users of Spacelink .
A comparison is made of a solar power satellite ( SPS ) concept in geostationary Earth orbit to a concentrating solar power ( CSP ) system on the ground to analyze overall efficiencies of each infrastructure from solar radiance at 1 AU to conversion and transmission of electrical energy into the power grid on the Earth 's surface . Each system is sized for a 1 - gigawatt output to the power grid and then further analyzed to determine primary collector infrastructure areas . Findings indicate that even though the SPS concept has a higher end - to - end efficiency , the combined space and ground collector infrastructure is still about the same size as a comparable CSP system on the ground .
The purose : a ) Customer 's perspective on Space Shuttle Return to Flight instrumentation ; b ) Focus on the difficult instrumentation issues ; and c ) Enable a discussion of new technologies ( i.e.- NANO / MEMS / Small Tech ) that could enhance Shuttle instrumentation posture . The T-10 Umbilical allows the vehicle instruments to be monitored and recorded prior to each launch and retract during launch . Launch Complex Instrumentation are instruments needed for assessment of Launch Commit Criteria ( LCC ) Salt - air and launch environments are issues . Instrumentation ( Drag - On Instrumentation ) can be added as needed to the vehicle for non - flight use . The current Roll - out Fatigue Testing is a primary example .
In this paper , we present an approach that enables the automatic generation of high quality schedules , with respect to a given objective function . The approach involves the combination of two techniques : GenH , which automatically generates a search heuristic specialized to the given problem instance , and HBSS , which employs the generated heuristic as a bias within a stochastic sampling method .
A brief overview of emerging materials technologies . Exploring the weight reduction benefit of replacing Carbon Fiber with Carbon Nanotube ( CNT ) in Polymer Composites . Review of the benign purification method developed for CNT sheets . The future of manufacturing will include the integration of computational material design and big data analytics , along with Nanomaterials as building blocks .
Combined radiation / conduction heat transfer through unbonded alumina fibrous insulation was modeled using the diffusion approximation for modeling the radiation component of heat transfer in the optically thick insulation . The validity of the heat transfer model was investigated by comparison to previously reported experimental effective thermal conductivity data over the insulation density range of 24 to 96 kg / cu m , with a pressure range of 0.001 to 750 torr ( 0.1 to 101.3 x 10(exp 3 ) Pa ) , and test sample hot side temperature range of 530 to 1360 K. The model was further validated by comparison to thermal conductivity measurements using the transient step heating technique on an insulation sample at a density of 144 kg / cu m over a pressure range of 0.001 to 760 torr , and temperature range of 290 to 1090 K.
A study into the effects of altitude on an aircraft thermal Ice Protection System ( IPS ) performance has been conducted by the National Research Council Canada ( NRC ) in collaboration with the NASA Glenn Icing Branch . The study included tests of an airfoil model , with a heated - air IPS , installed in the NRCs Altitude Icing Wind Tunnel ( AIWT ) at altitude and ground level conditions .
Not only has the number of launched spacecraft per year exploded over the past few years , but also spacecraft are getting progressively more complex , as flyby missions give way to   remote orbiters , which in turn give way to rovers and other in situ explorers .   To address the software issues in this expanding mission set , JPL started the Mission Data System ( MDS )   project , an effort to make flight software engineering more straightforward and less prone to error through the eplicit modeling of spacecraft state .   This paper presents how MDS   performs mission planning and execution in the context of explicitly managing spacecraft state .
This research examined the feasibility of incorporating an acoustic metric into the optimization of an aircraft trajectory to reduce the noise experienced by an observer . The method investigated a perturbed path of an unmanned aerial system with specified boundary conditions on position and velocity while maintaining a nominal flight speed . An acoustic model based on Gutin ’s work was developed to estimate propeller noise as a function of flight parameters , propulsion characteristics , and spatial location . A trajectory was then optimized a priori to reduce the noise experienced by an observer . Multiple simulations were performed and results showed that integrating an acoustic metric into the path planning process could be used to reduce the noise impact on an observer with no perturbation to the nominal flight speed .
Two developments in the direct calculation of the angular differential scattering amplitude have been implemented : ( a ) The integral expansion of the scattering amplitude is simplified by analytically integration over the azimuthal angle . ( b ) The resulting integral as a function of scattering angle is calculated by using the numerically generated wave function from a finite element method calculation . Results for electron - hydrogen scattering in the static approximation will be shown to be as accurate as a partial wave expansion with as many l 's as is necessary for convergence at the incident energy being calculated .
Many regions in America are experiencing downward trends in the number of practicing physicians and the number of available physician hours , resulting in a worrisome decrease in the availability of health care services . Recent changes in American health care legislation may induce a rapid change in the demand for health care services , which in turn will result in a new supply - demand equilibrium . In this paper we develop a system dynamics model linking physician availability to health care demand and profitability . We use this model to explore scenarios based on different initial conditions and describe possible outcomes for a range of different policy decisions .
Tribology experiments on different types of sputtered molybdenum disulfide ( MoS2 ) coatings ( obtained from different vendors ) using accelerated testing techniques were conducted . The purpose was to determine which would be the best coating for use with auxiliary journal bearings for spacecraft energy storage flywheels . Experiments were conducted in moist air ( 50 % relative humidity ) and in dry air ( < 100 PPM water vapor content ) on a Pin - on - Disk Tribometer to determine how well the coatings would perform in air . Experiments were also conducted on a Block - on - Ring Tribometer in dry nitrogen ( < 100 PPM water vapor ) to simulate how well the coatings would perform in vacuum . Friction , counterface wear , coating wear , endurance life and surface morphology were investigated .
The objective of this project was to introduce a series of plastic recycling experiments to students in materials - related courses such as materials science , material technology and materials testing . With the plastic recycling experiments , students not only can learn the fundamentals of plastic processing and properties as in conventional materials courses , but also can be exposed to the issue of materials life cycle and the impact on society and environment .
This paper will describe in detail thermal / structural analyses of SIRCA tiles which were performed at NASA Ames under the The Tile Analysis Task of the X-34 Program . The analyses used the COSMOS / M finite element software to simulate the material response in arc - jet tests , mechanical deflection tests , and the performance of candidate designs for the TPS system . Purposes of the analysis were to verify thermal and structural models for the SIRCA tiles , to establish failure criteria for stressed tiles , to simulate the TPS response under flight aerothermal and mechanical load , and to confirm that adequate safety margins exist for the actual TPS design .
A major new NASA initiative on environmental change and health has been established to promote the application of Earth science remote sensing data , information , observations , and technologies to issues of human health . NASA 's Earth Sciences suite of Earth observing instruments are now providing improved observations science , data , and advanced technologies about the Earth 's land , atmosphere , and oceans . These new space - based resources are being combined with other agency and university resources , data integration and fusion technologies , geographic information systems ( GIS ) , and the spectrum of tools available from the public health community , making it possible to better understand how the environment and climate are linked to specific diseases , to improve outbreak prediction , and to minimize disease risk . This presentation is an overview of NASA 's tools , capabilities , and research advances in this initiative .
The field of astrochemistry investigates the origin of the chemicals necessary for the formation of life . Astrochemists use remote observations , laboratory simulations , and analysis of extraterrestrial samples to understand the inventory of pre biotic chemicals present on the early Earth . Among the problems investigated by astrochemists is the origin of homo chirality in terrestrial life . Analysis of meteorites shows that they may have delivered an excess of L - amino acids to the Earth 's surface , perhaps leading to homochirality .