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At least 865 records · Page 48

Spectral Analysis Tool 6.2 for Windows

Spectral Analysis Tool 6.2 is the latest version of a computer program that assists in analysis of interference between radio signals of the types most commonly used in Earth/spacecraft radio communications. [An earlier version was reported in Software for Analyzing Earth/Spacecraft Radio Interference (NPO-20422), NASA Tech Briefs, Vol. 25, No. 4 (April 2001), page 52.] SAT 6.2 calculates signal spectra, bandwidths, and interference effects for several families of modulation schemes. Several types of filters can be modeled, and the program calculates and displays signal spectra after filtering by any of the modeled filters. The program accommodates two simultaneous signals: a desired signal and an interferer. The interference-to-signal power ratio can be calculated for the filtered desired and interfering signals. Bandwidth-occupancy and link-budget calculators are included for the user s convenience. SAT 6.2 has a new software structure and provides a new user interface that is both intuitive and convenient. SAT 6.2 incorporates multi-tasking, multi-threaded execution, virtual memory management, and a dynamic link library. SAT 6.2 is designed for use on 32- bit computers employing Microsoft Windows operating systems.

Morgan, Feiming↗

Experimental Technique for Producing and Recording Precise Particle Impacts on Transparent Window Materials

A new facility for making small particle impacts is being developed at NASA. Current sand/particle impact facilities are an erosion test and do not precisely measure and document the size and velocity of each of the impacting particles. In addition, evidence of individual impacts is often obscured by subsequent impacts. This facility will allow the number, size, and velocity of each particle to be measured and adjusted. It will also be possible to determine which particle produced damage at a given location on the target. The particle size and velocity will be measured by high speed imaging techniques. Information as to the extent of damage and debris from impacts will also be recorded. It will be possible to track these secondary particles, measuring size and velocity. It is anticipated that this additional degree of detail will provide input for erosion models and also help determine the impact physics of the erosion process. Particle impacts will be recorded at 90 degrees to the particle flight path and also from the top looking through the target window material.

Gray, Perry↗

Fused Silica and Other Transparent Window Materials

Several transparent ceramics, such as spinel and AlONs are now being produced in sufficient large areas to be used in space craft window applications. The work horse transparent material for space missions from Apollo to the International Space Station has been fused silica due in part to its low coefficient of expansion and optical quality. Despite its successful use, fused silica exhibits anomalies in its crack growth behavior, depending on environmental preconditioning and surface damage. This presentation will compare recent optical ceramics to fused silica and discuss sources of variation in slow crack growth behavior.

Optical Ceramics↗

Simulations of Li+ in Ionic Liquids: Structure, Transport, and Electrochemical Windows

Ionic liquids have been proposed as candidate electrolytes for a number of electrochemical applications. The Li+ solvation structure in these liquids is of central importance to electrolyte properties, like ionic conductivity and electrochemical stability. To this point, we employ simulations at three different size scales to better understand various aspects of the interplay between Li+ solvation structure and dynamics. The smallest systems are Li(Anion)n clusters that are treated with high-accuracy density functional theory (DFT) techniques to provide insight into solvation shell structure through energetics and comparisons to experimental IRRaman spectra. Mid-range sized liquid-phase systems (12-24 ion pairs) are treated with DFT molecular dynamics (MD) to provide temperature-dependent insight into Li+ solvation structure, diffusion, and electrochemical window. The largest systems (144-216 ion pairs) are treated with polarizable MD simulations to evaluate the influence of Li-networks on structure and provide size independent values of transport properties. We perform this procedure on three technologically important ionic liquids and comment on property correlations with solvation structure.

batteries↗

Tropical SNO Comparisons of AIRS and CrIS Calibration for Windows

AIRS (Atmospheric Infrared Sounder) on EOS (Earth Observing System)-Aqua and CrIS (Cross-track Infrared Sounder) on Suomi NPP (National Polar-orbiting Partnership) are two hyperspectral infrared sounders with similar capabilities and orbits, so there is a great opportunity to compare their absolute calibration while they are both in orbit. This insures that long-term climate record can be created by concatenating the two instrument records. There are significant differences in instrument architecture which may lead to subtle differences and complicate attempts to combine the records. We use Tropical Simultaneous Nadir Observations (TSNOs), cases where both instruments are looking nearly at the same place at the same time, to explore the differences. Due to the presence of cold clouds and clear hot desert surface, the data cover a brightness temperature range from 190 degrees Kelvin to 340 degrees Kelvin. We concentrate on the differences between the mean of the two instruments using atmospheric window channels as function of brightness temperature in 20-degree-Kelvin wide bins. With the currently available AIRS and CrIS official calibrated data, radiometric differences as large as 0.3 degrees Kelvin are seen at the extreme temperatures. These differences may be reduced in future releases of the AIRS and CrIS calibration.

CrIS↗

Two-Year Cosmology Large Angular Scale Surveyor (CLASS) Observations: 40GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance

The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background (CMB) over 75% of the sky from the Atacama Desert, Chile, at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures the large angular scale (1°~< θ >=90°) CMB polarization to constrain the tensor-to-scalar ratio at the r ∼ 0.01 level and the optical depth to last scattering to the sample variance limit. This paper presents the optical characterization of the 40 GHz telescope during its first observation era, from 2016 September to 2018 February. High signal-to-noise observations of the Moon establish the pointing and beam calibration. The telescope boresight pointing variation is <0°. 023 (<1.6% of the beam’s full width at half maximum (FWHM)). We estimate beam parameters per detector and in aggregate, as in the CMB survey maps. The aggregate beam has an FWHM of 1°.579 ± 0°.001 and a solid angle of 838 ± 6 μsr, consistent with physical optics simulations. The corresponding beam window function has a sub-percent error per multipole at ℓ < 200. An extended 90° beam map reveals no significant far sidelobes. The observed Moon polarization shows that the instrument polarization angles are consistent with the optical model and that the temperature-to-polarization leakage fraction is <10(exp −4) (95% C.L.). We find that the Moon-based results are consistent with measurements of M42, RCW 38, and Tau A from CLASS’s CMB survey data. In particular, Tau A measurements establish degree- level precision for instrument polarization angles.

Xu, Zhilei↗

A window on the composition of the early solar nebula: 2014MU69, Pluto, and Phoebe

The initial chemical composition of any solar nebula will depend upon the degree to which 1) organic and ice components form on dust grains, 2) organic and molecular species form in the gas phase, 3) organics and ices are exchanged between the gas and solid state, and 4) the precursor and newly formed (more complex) materials survive and are modified in the developing planetary system. Infrared and radio observations of star-forming regions reveal that complex chemistry occurs on icy grains, sometimes before stars even form. Additional processing, through the protosolar disk and within the solar nebula further modifies most, but probably not all, of the initial materials. In fact, the modern Solar System still carries a fraction of its interstellar inheritance [Alexander et al., 2017]. Here we focus on three examples of small bodies in our Solar System, each containing chemical and dynamical clues to its origin and evolution: the small, cold-classical Kuiper Belt object (KBO) 2014MU69 , Pluto and Saturn’s moon, Phoebe. The New Horizons flyby of 2014 MU69 has given the first view of an unaltered body composed of material originally in the solar nebula at ~45 AU. The spectrum reveals methanol ice (not commonly found), a possible detection of water ice (Stern et al. 2019). Pluto’s internal and surface inventory of volatiles and complex organics, together with active geological processes including cryo-volcanism, indicate a surprising level of activity on a body in the outermost region of the Solar System, and the fluid that emerges from subsurface reservoirs may contain material inherited from the solar nebula (Cruikshank et al. 2019). Meanwhile, Saturn's captured moon, Phoebe, carries high D/H in H2O [Clark et al. 2018)], and complex organics (Cruikshank et al. 2008), both consistent with its formation in, and inheritance from, the outer solar nebula. Together, these objects provide windows on the origin and evolution of our Solar System and constraints to be considered in future chemical and physical models of PPDs. The Spitzer Space telescope discovered the ring of dust around Saturn that emanated from the bombardment of Phoebe in the recent past, dislodging primitive Solar System material from deep within that satellite. In addition, Spitzer has provided detailed studies of the chemistry of star forming regions where methanol and other ices are readily observed. As a result of these and other observations, protoplanetary disk models are beginning to combine both dynamical and chemical complexities into their codes, resulting in new insights for exoplanetary systems.

Yvonne J. Pendleton↗

Space Launch System Launch Window and Day of Launch Processes

Lunar missions benefit from varying the launch azimuth as a function of launch time to allow longer launch windows with minimum performance impacts. This variable azimuth approach allows the vehicle to track the Moon’s apparent motion due to Earth’s rotation . The Space Launch System (SLS) Block 1 vehicle design requires the mission to launch into an elliptical parking orbit to provide sufficient energy to insert Orion into a trans-lunar trajectory. The primary benefit of varying the launch azimuth, and as a result the parking orbit inclination, allows the SLS Interim Cryogenic Propulsion Stage (ICPS) to perform its Trans-Lunar Injection (TLI) burn closer to perigee and take advantage of performing a burn in a location where the burn will primarily raise apogee.

A. S. Craig↗

Virtual Window Telepresence System for Telerobotics Inspection

Telerobotic inspection can be used in environments that are too hazardous, removed or expensive for direct human inspection. Telerobotic inspection is a complex task requiring an operator to control and coordinate a robot and sensors, while monitoring and interpreting sensor data to detect flaws. A virtual window telepresence system has been developed to aid the operator in performing these inspections.

telepresnece↗

Mapping the Interstellar Reddening and Extinction toward Baade's Window Using Minimum Light Colors of ab-type RR Lyrae Stars: Revelations from the De-reddened Color–Magnitude Diagrams

We have obtained repeated images of six fields toward the Galactic bulge in five passbands (u, g, r, i, z) with the DECam imager on the Blanco 4 m telescope at CTIO. From more than 1.6 billion individual photometric measurements in the field centered on Baade’s window, we have detected 4877 putative variable stars. A total of 474 of these have been confirmed as fundamental mode RR Lyrae stars, whose colors at minimum light yield line-of- sight reddening determinations, as well as a reddenning law toward the Galactic Bulge, which differs significantly from the standard R(V) = 3.1 formulation. Assuming that the stellar mix is invariant over the 3 square-degree field, we are able to derive a line-of-sight reddening map with sub-arcminute resolution, enabling us to obtain de-reddened and extinction corrected color–magnitude diagrams (CMDs) of this bulge field using up to 2.5 million well-measured stars. The corrected CMDs show unprecedented detail and expose sparsely populated sequences: for example, delineation of the very wide red giant branch, structure within the red giant clump, the full extent of the horizontal branch, and a surprising bright feature that is likely due to stars with ages younger than 1 Gyr. We use the RR Lyrae stars to trace the spatial structure of the ancient stars and find an exponential decline in density with Galactocentric distance. We discuss ways in which our data products can be used to explore the age and metallicity properties of the bulge, and how our larger list of all variables is useful for learning to interpret future LSST alerts.

Abhijit Saha↗

Equuleus Launch Window Analysis and Mission Design

This paper presents the trajectory design process for EQUULEUS, a 6U CubeSat developed by JAXA and the University of Tokyo that is scheduled to launch as a piggyback of NASA’s Artemis 1. After separation from the upper stage of the Space Launch System, EQUULEUS will maneuver along a low-energy transfer to an Earth–Moon quasi-rectilinear halo orbit in 1-to-4 resonance with the lunar synodic period. As a secondary payload, the trajectory of EQUULEUS needs to be compatible with the requirements of the primary mission, but also robust against disturbances and potential changes in the deployment state. Realistic initial conditions spanning two years of potential launch windows are processed and the solution structure for optimal lunar transfers is analyzed. A host of candidate solutions is presented, compatibly with the fuel and power limitations of EQUULEUS. The global understanding of the solution space is shown to be insightful for the design of robust trajectories for limited control-authority spacecraft.

Kawakatsu, Yasuhiro↗

Melt Inclusions in Zircon: A Window to Understanding the Structure and Evolution of the Magmatic System Beneath the Laguna del Maule Volcanic Field

Explosive silicic eruptions pose a significant threat to society, yet the development and destabilization of the underlying silicic magmatic systems are still controversial. Zircons provide simultaneous information on the trace element composition and age of silicic magmatic systems, while melt inclusions in quartz and plagioclase yield important constraints on their volatile content as well as storage depth. Melt inclusions in zircons (MIZs) combine these data from a single mineral grain, recording the age, storage depth, temperature, and composition of magmas, and thus provide unique constraints on the structure and evolution of silicic magmatic systems. We studied MIZs from the Laguna del Maule (LdM) volcanic field in the southern Andes that is among the most active Pleistocene-Holocene rhyolitic volcanic centers worldwide and a potentially hazardous system displaying inflation rates in excess of 25 cm/yr. The host zircon ages suggest that the LdM MIZ record extends to ~30 kyr before eruption, in contrast to the melt inclusions in LdM plagioclase and quartz crystals that formed only decades to centuries before eruption. The major element compositions of MIZs are minimally affected by post-entrapment crystallization, and agree well with the LdM rhyolitic whole rock data. The more evolved major element composition of rle MIZs than rdm MIZs, suggests a long-term deeper connection of the rdm crystal mush to a more primitive magma body than that of the rle. The evidence of slow H diffusion observed in MIZs suggest that their H 2 O contents are not significantly affected by diffusion of H through the host zircon. The storage depths of 1.1 to 2.8 kbars recorded by the H 2 O contents of rdm and rle MIZs are consistent with the optimal emplacement window (2.0 ± 0.5 kbar) of silicic magma reservoir growth, storage, and eruptibility based on thermomechanical modeling (Huber et al. 2019).

Kei Shimizu↗

Window Spacers and Edge Seals in Insulating Glass Units: A State-of-the-Art Review and Future Perspectives

Insulating glass (IG) units typically consist of multiple glass panes that are sealed and held together structurally along their perimeters. This report describes a study of edge seals in IG units. First, we summarize the components, requirements, and desired properties of edge construction in IG units, based on a survey of the available literature. Second, we review commercially available window edge seals and describe their properties, to provide an easily accessible reference for research and commercial purposes. Finally, based on the literature survey and review of current commercial edge seal systems, we identify research opportunities for future edge seal improvements and solutions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

The Open Host Network Packet Process Correlator for Windows

The Hone sensors are packet-process correlation engines that log the relationships between applications and the communications they are responsible for. Hone sensors are available for a variety of platforms including Linux, Windows, and MacOSX. Hone sensors are designed to help analysts understand the meaning of communications on a deeper level by associating the origin or destination process to the communication. They do this by tracing communications on a per-packet basis, through the kernel of the operating system to determine their ultimate source/destination on the monitored machine.

Source record↗

RF window assembly comprising a ceramic disk disposed within a cylindrical waveguide which is connected to rectangular waveguides through elliptical joints

A high-power microwave RF window is provided that includes a cylindrical waveguide, where the cylindrical waveguide includes a ceramic disk concentrically housed in a central region of the cylindrical waveguide, a first rectangular waveguide, where the first rectangular waveguide is connected by a first elliptical joint to a proximal end of the cylindrical waveguide, and a second rectangular waveguide, where the second rectangular waveguide is connected by a second elliptical joint to a distal end of the cylindrical waveguide.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Exploring Windows Domain-Level Defenses Against Authentication Attacks

We investigated the security resilience of the current Windows Active Directory (AD) environments to Pass-the-Hash and Pass- the-Ticket credential theft attacks. While doing this, we discovered a way to trigger the removal of all previously issued authentication credentials for a client, thus preventing their use by attackers. After triggered, the user is forced to contact the domain administrators and to authenticate to the AD to continue. This could become the basis for a response that arrests the spread of a detected attack. Operating in a virtualized XenServer environment, we were able to carefully determine and recreate the conditions necessary to cause this response.

Curtis, Laura↗

Insulated window frame system

The present invention provides for a window frame comprising a rigid framework cross-section comprising a truss structure.

36 MATERIALS SCIENCE↗

Two dimensional meta-material windows

Conductive nanoshells are oriented so as to redirect incident radiation as a function of wavelength. Nanoshells can be formed on templates such as nanospheres or gratings and embedded in an elastomeric layer. In some examples, conductive nanoshells are coupled to a layer that is configured to unbuckle and buckle as a function of temperature, so that radiation in one or more wavelength ranges is directed differently at different temperatures. Building windows can include such layers to that infrared radiation is reflected on warm days and directed into a building on cool days. Such layers can also direct incident visible radiation to a room ceiling so as to enhance interior lighting.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗