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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Alignment and Test of the Wide Field Infrared Survey Telescope (WFIRST) Engineering Design Unit (EDU) Grism

The WFIRST wide field instrument (WFI) includes a slitless spectrometer, which plays an important role in the WFIRST mission for the survey of emission-line galaxies. WFI is building engineering design and environmental test (EDU and ETU) units to reduce risk for the flight grism unit. We report here on successful build and test of the EDU grism. The four-element EDU grism consists of two prism elements and two diffractive elements that provide R700 dispersion. The elements were fabricated with alignment fiducials and integral flats to allow opto-mechanical alignment in six-degrees of freedom. Each element in turn, was installed onto a hexapod and positioned to its nominal orientation relative to the grism deck, then bonded into individual cells. Alignment measurements were performed in situ using theodolites to set tip/tilt and a Micro-vu non-contact Multisensor Measurement System was used to set despace, decenter and clocking of each element using the hexapod. After opto-mechanical alignment, the grism wavefront was measured using an Infrared ZYGO interferometer at various field points extending over a 20 by 14- degree (local) field of view. Using modeled alignment sensitivities, we determined the alignment correction required on our Element 2 prism compensator and successfully minimized the field dependent wavefront error and confocality. This paper details the alignment and testing of the EDU grism at ambient and cold operating temperatures.

Hagopian, John↗
DOE OSTI2012

Alignment method for solar collector arrays

The present invention is directed to an improved method for establishing camera fixture location for aligning mirrors on a solar collector array (SCA) comprising multiple mirror modules. The method aligns the mirrors on a module by comparing the location of the receiver image in photographs with the predicted theoretical receiver image location. To accurately align an entire SCA, a common reference is used for all of the individual module images within the SCA. The improved method can use relative pixel location information in digital photographs along with alignment fixture inclinometer data to calculate relative locations of the fixture between modules. The absolute locations are determined by minimizing alignment asymmetry for the SCA. The method inherently aligns all of the mirrors in an SCA to the receiver, even with receiver position and module-to-module alignment errors.

14 SOLAR ENERGY↗
DOE OSTI2017

Mechanical design of multiple zone plates precision alignment apparatus for hard X-ray focusing in twenty-nanometer scale

An enhanced mechanical design of multiple zone plates precision alignment apparatus for hard x-ray focusing in a twenty-nanometer scale is provided. The precision alignment apparatus includes a zone plate alignment base frame; a plurality of zone plates; and a plurality of zone plate holders, each said zone plate holder for mounting and aligning a respective zone plate for hard x-ray focusing. At least one respective positioning stage drives and positions each respective zone plate holder. Each respective positioning stage is mounted on the zone plate alignment base frame. A respective linkage component connects each respective positioning stage and the respective zone plate holder. The zone plate alignment base frame, each zone plate holder and each linkage component is formed of a selected material for providing thermal expansion stability and positioning stability for the precision alignment apparatus.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Scalable electric-field-assisted fabrication of vertically aligned carbon nanotube membranes with flow enhancement

In this work, we report a solution-based approach for fabricating vertically aligned carbon-nanotube (VACNT) membranes, which improves on the unaligned nature of CNT mixed-matrix membranes. This approach addresses important challenges regarding scalability and incorporation of different types and sizes of nanotube as pores in a membrane. In a new, solvent-deposition approach, CNTs are dispersed and then aligned and concentrated via electro-deposition from an organic solvent, using a composite AC + DC electric field to form aligned CNT arrays. This enables VACNT number densities that are two orders-of-magnitude higher than possible from direct suspension of CNTs in the liquid oligomer. The solvent is then replaced by a UV-curable oligomer, which is selectively cured to form macroscopic membranes of highly controlled thickness. After plasma etching to open pores, the VACNT membranes are shown to be permeable, and to have pore sizes consistent with flow through internal channels of the CNTs. In a first for field-aligned, solution-fabricated VACNT membranes, the pores show substantial, 100–300 × , gas-flow enhancement compared to theory, similar to membranes fabricated via less scalable methods (i.e., by CVD growth of already aligned CNT forests). The solution-based, electric-field-assisted approach aligns nanotubes of different sizes and types grown by any means, and is scalable to the efficient fabrication of large-area VACNT membranes for a variety of important applications.

36 MATERIALS SCIENCE↗
DOE OSTI2011

2011 Status of the Automatic Alignment System for the National Ignition Facility

Automated alignment for the National Ignition Facility (NIF) is accomplished using a large-scale parallel control system that directs 192 laser beams along the 300-m optical path. The beams are then focused down to a 50-micron spot in the middle of the target chamber. The entire process is completed in less than 50 minutes. The alignment system commands 9,000 stepping motors for highly accurate adjustment of mirrors and other optics. 41 control loops per beamline perform parallel processing services running on a LINUX cluster to analyze high-resolution images of the beams and their references. This paper describes the status the NIF automatic alignment system and the challenges encountered as NIF development has transitioned from building the laser, to becoming a research project supporting a 24 hour, 7 day laser facility. NIF is now a continuously operated system where performance monitoring is increasingly more critical for operation, maintenance, and commissioning tasks. Equipment wear and the effects of high energy neutrons from fusion experiments are issues which alter alignment efficiency and accuracy. New sensors needing automatic alignment assistance are common. System modifications to improve efficiency and accuracy are prevalent. Handling these evolving alignment and maintenance needs while minimizing the impact on NIF experiment schedule is expected to be an on-going challenge for the planned 30 year operational life of NIF.

42 ENGINEERING↗
DOE OSTI2023

Alignment of the CLAS12 central hybrid tracker with a Kalman Filter

Several factors can contribute to the difficulty of aligning the sensors of tracking detectors, including a large number of modules, multiple types of detector technologies, and non-linear strip patterns on the sensors. All three of these factors apply to the CLAS12 CVT, which is a hybrid detector consisting of planar silicon sensors with non-parallel strips, and cylindrical micromegas sensors with longitudinal and arc-shaped strips located within a 5 T superconducting solenoid. To align this detector, we used the Kalman Alignment Algorithm, which accounts for correlations between the alignment parameters without requiring the time-consuming inversion of large matrices. This is the first time that this algorithm has been adapted for use with hybrid technologies, non-parallel strips, and curved sensors. We present the results for the first alignment of the CLAS12 CVT using straight tracks from cosmic rays and from a target with the magnetic field turned off. After running this procedure, we achieved alignment at the level of 10 µm, and the widths of the residual spectra were greatly reduced. These results attest to the flexibility of this algorithm and its applicability to future use in the CLAS12 CVT and other hybrid or curved trackers, such as those proposed for the future Electron-Ion Collider.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

THE SPIN ALIGNMENTS IN GALAXY PAIRS AS A TEST OF BOUNCING COUPLED DARK ENERGY

We investigate the effect of coupled dark energy (cDE) on the spin alignments in isolated pairs of galactic halos using the publicly available data from the hydrodynamic cDE simulations (H-CoDECs) that were run for various cDE models such as EXP001, EXP002, EXP003 (with exponential potential and constant coupling), EXP008e3 (with exponential potential and exponential coupling), and SUGRA003 (with supergravity potential and negative constant coupling), as well as for a standard {Lambda}CDM cosmology (with the WMAP7 parameters). Measuring the cosines of the angles between the spin axes in isolated pairs of galactic halos for each model and determining its probability density distribution, we show that for the SUGRA003 model with bouncing cDE the null hypothesis of no spin alignment in pairs of galactic halos is rejected at a 99.999% confidence level. In contrast, the {Lambda}CDM cosmology yields no significant signal of spin alignment, and the other four cDE models also exhibit only weak signals of spin alignments. The strength of the spin alignment signal is found to be almost independent of the total halo mass and separation distance in galaxy pairs. Showing also that no signal is detected from the Sloan Digital Sky Survey DR 7, we conclude that the spin alignments in galaxy pairs are in principle a unique test of bouncing cDE models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

ANALYSIS OF SPIN-ORBIT ALIGNMENT IN THE WASP-32, WASP-38, AND HAT-P-27/WASP-40 SYSTEMS

We present measurements of the spin-orbit alignment angle, {lambda}, for the hot Jupiter systems WASP-32, WASP-38, and HAT-P-27/WASP-40, based on data obtained using the HARPS spectrograph. We analyze the Rossiter-McLaughlin effect for all three systems and also carry out Doppler tomography for WASP-32 and WASP-38. We find that WASP-32 (T {sub eff} = 6140{sup +90} {sub -100} K) is aligned, with an alignment angle of {lambda} = 10.{sup 0}5{sup +6.4} {sub -6.5} obtained through tomography, and that WASP-38 (T {sub eff} = 6180{sup +40} {sub -60} K) is also aligned, with tomographic analysis yielding {lambda} = 7.{sup 0}5{sup +4.7} {sub -6.1}. The latter result provides an order-of-magnitude improvement in the uncertainty in {lambda} compared to the previous analysis of Simpson et al. We are only able to loosely constrain the angle for HAT-P-27/WASP-40 (T{sub eff} = 5190{sup +160} {sub -170} K) to {lambda} = 24.{sup 0}2{sup +76.0}{sub -44.5}, owing to the poor signal-to-noise ratio of our data. We consider this result a non-detection under a slightly updated version of the alignment test of Brown et al. We place our results in the context of the full sample of spin-orbit alignment measurements, finding that they provide further support for previously established trends.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Spin-orbit alignment for 110 day period KOI368.01 from gravity darkening

We fit the Kepler photometric light curve of the KOI-368 system using an oblate, gravity-darkened stellar model in order to constrain its spin-orbit alignment. We find that the system is relatively well-aligned with a sky-projected spin-orbit alignment of λ = 10° ± 2°, a stellar obliquity of ψ = 3° ± 7°, and a true spin-orbit alignment of ψ = 11° ± 3°. Although our measurement differs significantly from zero, the low value for ψ is consistent with spin-orbit alignment. We also measure various transit parameters of the KOI-368 system: R {sub KOI-368} = 2.28 ± 0.02 R {sub ☉}, R{sub p} = 1.83 ± 0.02 R {sub jup}, and i = 89.°221 ± 0.°013. This work shows that our gravity-darkened model can constrain long-period, well-aligned planets and M-class stars orbiting fast-rotators, allowing for measurement of a new subcategory of transiting bodies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Physically motivated global alignment method for electron tomography

Electron tomography is widely used for nanoscale determination of 3-D structures in many areas of science. Determining the 3-D structure of a sample from electron tomography involves three major steps: acquisition of sequence of 2-D projection images of the sample with the electron microscope, alignment of the images to a common coordinate system, and 3-D reconstruction and segmentation of the sample from the aligned image data. The resolution of the 3-D reconstruction is directly influenced by the accuracy of the alignment, and therefore, it is crucial to have a robust and dependable alignment method. In this paper, we develop a new alignment method which avoids the use of markers and instead traces the computed paths of many identifiable ‘local’ center-of-mass points as the sample is rotated. Compared with traditional correlation schemes, the alignment method presented here is resistant to cumulative error observed from correlation techniques, has very rigorous mathematical justification, and is very robust since many points and paths are used, all of which inevitably improves the quality of the reconstruction and confidence in the scientific results.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Discontinuous Aligned Carbon Fiber Intermediates for Automotive and Related Applications

This work focused on preferentially aligning discontinuous carbon fibers in wet-laid or air-laid processes. It is well known that aligned fibers provides higher directional strength and stiffness. Discontinuous fibers further allow higher degree of draw and formability as the gaps in the fibers allow for higher material movement. The current processes are limited in their ability to align carbon fibers during processing. The aligned fibers have several benefits - (a) in applications where chopped fibers can replace continuous fibers for targeted strength and stiffness metrics, but at a substantially reduced cost; (b) they can tolerate deeper draws than continuous fiber composites in thermo-stamping and compression molding processes; (c) they can be tailored for pultrusion and unidirectional applications. Although pultrusion is primarily a process that adopts continuous fibers, stitch bonded entangled discontinuous fibers can provide unique intermediates. This is analogous to natural coir fibers which get aligned and entangled to produce ropes/rods for example, (d) they can be processed in cross-ply and multi-directional formats, like composite laminates. In this work Neenah Paper partnered with IACMI, UT and ORNL to evaluate structure-process-property relationships with Zoltek carbon fiber. A few process parameters such as machine speed, weight basis, fiber length, effect of fiber sizing, direction of mat lay-up etc. were investigated. The produced mats were converted to thermoplastic composite laminates using polyamide 6 (PA6, nylon) resin. The specific objective of this project is to produce a wet-laid nonwoven carbon fiber mat with a high degree of unidirectional fiber alignment, using discontinuous carbon fibers. The report provides details about the processing, characterization, and lower-upper bound properties.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Pairwise alignment for very long nucleic acid sequences

Highlights: • The PAAVLS algorithm can be employed for alignment of very long sequences. • The PAAVLS algorithm largely reduces memory demand as the Smith–Waterman algorithm. • The running times of the PAAVLS and Smith–Waterman algorithms are comparable. Sequence alignment is one of the fundamental problems in computational biology and has numerous applications. The Smith–Waterman algorithm generates optimal local alignment for pairwise alignment task and has become a standard algorithm in its field. However, the current version of the Smith–Waterman algorithm demands a significant amount of memory and is not suitable for alignment of very long sequences. On the hand, the recent DNA sequencing technologies have produced vast amounts of biological sequences. Some nucleic acid sequences are very long and cannot employ the Smith–Waterman algorithm. To this end, this study proposes the PAAVLS algorithm that follows the dynamic programming technique employed by the Smith–Waterman algorithm and largely reduces the demand of memory. The proposed PAAVLS algorithm can be employed for alignment of very long sequences, i.e., sequences contain more than 100,000,000 nucleotides, on a personal computer. Additionally, the running time of the proposed PAAVLS algorithm is comparable with the running time of the standard Smith–Waterman algorithm.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

SIMILE enables alignment of tandem mass spectra with statistical significance

Abstract Interrelating small molecules according to their aligned fragmentation spectra is central to tandem mass spectrometry-based untargeted metabolomics. Current alignment algorithms do not provide statistical significance and compounds that have multiple delocalized structural differences and therefore often fail to have their fragment ions aligned. Here we align fragmentation spectra with both statistical significance and allowance for multiple chemical differences using Significant Interrelation of MS/MS Ions via Laplacian Embedding (SIMILE). SIMILE yields spectral alignment inferred structural connections in molecular networks that are not found with cosine-based scoring algorithms. In addition, it is now possible to rank spectral alignments based on p-values in the exploration of structural relationships between compounds and enhance the chemical connectivity that can be obtained with molecular networking.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Electrokinetics of scalable, electric-field-assisted fabrication of vertically aligned carbon-nanotube/polymer composites

Composite thin films incorporating vertically aligned carbon nanotubes (VACNTs) offer promise for a variety of applications where the vertical alignment of the CNTs is critical to meet performance requirements, e.g., highly permeable membranes, thermal interfaces, dry adhesives, and films with anisotropic electrical conductivity. However, current VACNT fabrication techniques are complex and difficult to scale up. In this paper, we describe a solution-based, electric-field-assisted approach as a costeffective and scalable method to produce large-area VACNT composites. Multiwall-carbon nanotubes are dispersed in a polymeric matrix, aligned with an alternating-current (AC) electric field, and electrophoretically concentrated to one side of the thin film with a direct-current (DC) component to the electric field. This approach enables the fabrication of highly concentrated, individually aligned nanotube composites from suspensions of very dilute (Φ=4×10 –4 ) volume fraction. We experimentally investigate the basic electrokinetics of nanotube alignment under AC electric fields, and show that simple models can adequately predict the rate and degree of nanotube alignment using classical expressions for the induced dipole moment, hydrodynamic drag, and the effects of Brownian motion. The composite AC þ DC field also introduces complex fluid motion associated with AC electro-osmosis and the electrochemistry of the fluid/electrode interface. We experimentally probe the electric-field parameters behind these electrokinetic phenomena, and demonstrate, with suitable choices of processing parameters, the ability to scalably produce large-area composites containing VACNTs at number densities up to 10 10 nanotubes/cm 2 . This VACNT number density exceeds that of previous electric-fieldfabricated composites by an order of magnitude, and the surface-area coverage of the 40nm VACNTs is comparable to that of chemical-vapor-deposition-grown arrays of smaller-diameter nanotubes.

42 ENGINEERING↗
DOE OSTI2018

Intradomain phase transitions in flexible block copolymers with self-aligning segments

We study a model of flexible block copolymers (BCPs) in which there is an enlthalpic preference for orientational order, or local alignment, among like-block segments. We describe a generalization of the self-consistent field theory of flexible BCPs to include inter-segment orientational interactions via a Landau-de Gennes free energy associated with a polar or nematic order parameter for segments of one component of a diblock copolymer. We study the equilibrium states of this model numerically, using a pseudo-spectral approach to solve for chain conformation statistics in the presence of a self-consistent torque generated by inter-segment alignment forces. Applying this theory to the structure of lamellar domains composed of symmetric diblocks possessing a single block of “self-aligning” polar segments, we show the emergence of spatially complex segment order parameters (segment director fields) within a given lamellar domain. Because BCP phase separation gives rise to spatially inhomogeneous orientation order of segments even in the absence of explicit intra-segment aligning forces, the director fields of BCPs, as well as thermodynamics of lamellar domain formation, exhibit a highly non-linear dependence on both the inter-block segregation ( χ N ) and the enthalpy of alignment (ε). Specifically, we predict the stability of new phases of lamellar order in which distinct regions of alignment coexist within the single mesodomain and spontaneously break the symmetries of the lamella (or smectic) pattern of composition in the melt via in-plane tilt of the director in the centers of the like-composition domains. We further show that, in analogy to Freedericksz transition confined nematics, the elastic costs to reorient segments within the domain, as described by the Frank elasticity of the director, increase the threshold value ε needed to induce this intra-domain phase transition .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Alignment of magnetic particles in anisotropic Nd–Fe–B bonded magnets

High-performance anisotropic bonded magnets need a high volumetric filling fraction of magnetic powder in a polymer binder and good alignment while possessing adequate mechanical properties. The correlation between the degree of alignment (DOA) and the volumetric filling fraction of magnetic powder, the type of binder and the processing parameters have been studied using Nd–Fe–B anisotropic bonded magnets. Here, thermomagnetic analysis and differential scanning calorimetry results show that the magnetic powder can be well aligned in a bonded magnet under an external magnetic field at a temperature higher than the binders' melting point by 20–60 K, depending on the type of magnetic powder and binder. The DOA results mainly from the interplay between the Zeeman energy (E app ) and the inter-particle static energy (E stat ) in bonded magnets at the chosen alignment temperature and the magnetic fields. A good alignment can be achieved by an alignment magnetic field which is about twice its coercivity in an anisotropic Nd–Fe–B bonded magnet, which is confirmed by our experimental and modeling results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

End-to-end learning of multiple sequence alignments with differentiable Smith–Waterman

Abstract Motivation Multiple sequence alignments (MSAs) of homologous sequences contain information on structural and functional constraints and their evolutionary histories. Despite their importance for many downstream tasks, such as structure prediction, MSA generation is often treated as a separate pre-processing step, without any guidance from the application it will be used for. Results Here, we implement a smooth and differentiable version of the Smith–Waterman pairwise alignment algorithm that enables jointly learning an MSA and a downstream machine learning system in an end-to-end fashion. To demonstrate its utility, we introduce SMURF (Smooth Markov Unaligned Random Field), a new method that jointly learns an alignment and the parameters of a Markov Random Field for unsupervised contact prediction. We find that SMURF learns MSAs that mildly improve contact prediction on a diverse set of protein and RNA families. As a proof of concept, we demonstrate that by connecting our differentiable alignment module to AlphaFold2 and maximizing predicted confidence, we can learn MSAs that improve structure predictions over the initial MSAs. Interestingly, the alignments that improve AlphaFold predictions are self-inconsistent and can be viewed as adversarial. This work highlights the potential of differentiable dynamic programming to improve neural network pipelines that rely on an alignment and the potential dangers of optimizing predictions of protein sequences with methods that are not fully understood. Availability and implementation Our code and examples are available at: https://github.com/spetti/SMURF. Supplementary information Supplementary data are available at Bioinformatics online.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Intrinsic alignments of galaxies around cosmic voids

ABSTRACT The intrinsic alignments of galaxies, i.e. the correlation between galaxy shapes and their environment, are a major source of contamination for weak gravitational lensing surveys. Most studies of intrinsic alignments have so far focused on measuring and modelling the correlations of luminous red galaxies with galaxy positions or the filaments of the cosmic web. In this work, we investigate alignments around cosmic voids. We measure the intrinsic alignments of luminous red galaxies detected by the Sloan Digital Sky Survey around a sample of voids constructed from those same tracers and with radii in the ranges: [20–30; 30–40; 40–50] h−1 Mpc and in the redshift range z = 0.4−0.8. We present fits to the measurements based on a linear model at large scales, and on a new model based on the void density profile inside the void and in its neighbourhood. We constrain the free scaling amplitude of our model at small scales, finding no significant alignment at 1σ for either sample. We observe a deviation from the null hypothesis, at large scales, of 2σ for voids with radii between 20 and 30 h−1 Mpc, and 1.5σ for voids with radii between 30 and 40 h−1 Mpc and constrain the amplitude of the model on these scales. We find no significant deviation at 1σ for larger voids. Our work is a first attempt at detecting intrinsic alignments of galaxy shapes around voids and provides a useful framework for their mitigation in future void lensing studies.

79 ASTRONOMY AND ASTROPHYSICS↗