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All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Using Plate Finite Elements for Modeling Fillets in Design, Optimization, and Dynamic Analysis

A methodology has been developed that allows the use of plate elements instead of numerically inefficient solid elements for modeling structures with 90 degree fillets. The technique uses plate bridges with pseudo Young's modulus (Eb) and thickness (tb) values placed between the tangent points of the fillets. These parameters are obtained by solving two nonlinear simultaneous equations in terms of the independent variables rlt and twallt. These equations are generated by equating the rotation at the tangent point of a bridge system with that of a fillet, where both rotations are derived using beam theory. Accurate surface fits of the solutions are also presented to provide the user with closed-form equations for the parameters. The methodology was verified on the subcomponent level and with a representative filleted structure, where the technique yielded a plate model exhibiting a level of accuracy better than or equal to a high-fidelity solid model and with a 90-percent reduction in the number of DOFs. The application of this method for parametric design studies, optimization, and dynamic analysis should prove extremely beneficial for the finite element practitioner. Although the method does not attempt to produce accurate stresses in the filleted region, it can also be used to obtain stresses elsewhere in the structure for preliminary analysis. A future avenue of study is to extend the theory developed here to other fillet geometries, including fillet angles other than 90 and multifaceted intersections.

Brown, A. M.↗
NASA NTRS2013

Orion MPCV GN and C End-to-End Phasing Tests

End-to-end integration tests are critical risk reduction efforts for any complex vehicle. Phasing tests are an end-to-end integrated test that validates system directional phasing (polarity) from sensor measurement through software algorithms to end effector response. Phasing tests are typically performed on a fully integrated and assembled flight vehicle where sensors are stimulated by moving the vehicle and the effectors are observed for proper polarity. Orion Multi-Purpose Crew Vehicle (MPCV) Pad Abort 1 (PA-1) Phasing Test was conducted from inertial measurement to Launch Abort System (LAS). Orion Exploration Flight Test 1 (EFT-1) has two end-to-end phasing tests planned. The first test from inertial measurement to Crew Module (CM) reaction control system thrusters uses navigation and flight control system software algorithms to process commands. The second test from inertial measurement to CM S-Band Phased Array Antenna (PAA) uses navigation and communication system software algorithms to process commands. Future Orion flights include Ascent Abort Flight Test 2 (AA-2) and Exploration Mission 1 (EM-1). These flights will include additional or updated sensors, software algorithms and effectors. This paper will explore the implementation of end-to-end phasing tests on a flight vehicle which has many constraints, trade-offs and compromises. Orion PA-1 Phasing Test was conducted at White Sands Missile Range (WSMR) from March 4-6, 2010. This test decreased the risk of mission failure by demonstrating proper flight control system polarity. Demonstration was achieved by stimulating the primary navigation sensor, processing sensor data to commands and viewing propulsion response. PA-1 primary navigation sensor was a Space Integrated Inertial Navigation System (INS) and Global Positioning System (GPS) (SIGI) which has onboard processing, INS (3 accelerometers and 3 rate gyros) and no GPS receiver. SIGI data was processed by GN&C software into thrust magnitude and direction commands. The processing changes through three phases of powered flight: pitchover, downrange and reorientation. The primary inputs to GN&C are attitude position, attitude rates, angle of attack (AOA) and angle of sideslip (AOS). Pitch and yaw attitude and attitude rate responses were verified by using a flight spare SIGI mounted to a 2-axis rate table. AOA and AOS responses were verified by using a data recorded from SIGI movements on a robotic arm located at NASA Johnson Space Center. The data was consolidated and used in an open-loop data input to the SIGI. Propulsion was the Launch Abort System (LAS) Attitude Control Motor (ACM) which consisted of a solid motor with 8 nozzles. Each nozzle has active thrust control by varying throat area with a pintle. LAS ACM pintles are observable through optically transparent nozzle covers. SIGI movements on robot arm, SIGI rate table movements and LAS ACM pintle responses were video recorded as test artifacts for analysis and evaluation. The PA-1 Phasing Test design was determined based on test performance requirements, operational restrictions and EGSE capabilities. This development progressed during different stages. For convenience these development stages are initial, working group, tiger team, Engineering Review Team (ERT) and final.

Neumann, Brian C.↗
DOE OSTI2019

Crystal Structure, Magnetic and Electrical Properties of Half-Doped Chromium Manganite La{sub 0.5}Sr{sub 0.5}Mn{sub 0.5}Cr{sub 0.5}O{sub 3}

Polycrystalline sample La{sub 0.5}Sr{sub 0.5}Mn{sub 0.5}Cr{sub 0.5}O{sub 3} (LSMCO) was prepared by a conventional solid-state reaction method in the air, and its structure was determined by Rietveld refinement using consistent resolution time-of-flight X-ray diffraction. Different structural models have been used for analysis of X-ray diffraction data recorded at room temperature, but the best fits have been found using a mixture of rhombohedral and an orthorhombic structural phases (42(1)%/57(1)%). The rhombohedral, centro-symmetric space group R 3-bar c(No.167,a≈√2a{sub p},c≈2√3a{sub p},Z=6) with octahedral tilting scheme a{sup −}a{sup −}a{sup −} leading to a three identical out-of-phase tilt angle of (Mn/Cr)-O{sub 6} octahedron along three perovskite main directions: x, y, and z-axes. The orthorhombic space group Pbnm(No.62,a≈b≈√2a{sub p},c≈2a{sub p},Z=4) with octahedral tilting scheme a{sup −}a{sup −}c{sup +}, leads to an anti-phase tilts of the same magnitude about [100] and [010] directions of the elementary specimen cell and in-phase tilt of different magnitude about the [001] direction. At low temperature 10 K, Rietveld refinement of powder diffraction data revealed that the crystal structure of sample is distorted with a single orthorhombic symmetry (space group Pbnm). Magnetic measurements indicate that our investigated sample exhibits an overall anti-ferromagnetic behavior mainly attributed to the frustration induced by both competing AFM Cr{sup 3+}-O-Cr{sup 3+}, Mn{sup 4+}-O-Mn{sup 4+} networks, and the mixed one Mn{sup 4+}-O-Cr{sup 3+}exchange magnetic interactions. The temperature dependence of the resistivity measured under zero field shows a semi-conducting behavior in the whole temperature range, which probably could be described by the adiabatic small polaron hoping model with relatively high polaron activation energy.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Polarization-Independent Optical Broadband Angular Selectivity

Generalizing broadband angular selectivity to both polarizations has been a scientific challenge for a long time. Previous demonstrations of the broadband angular selectivity work only for one polarization. In this paper, we propose a method that can achieve polarization-independent optical broadband angular selectivity. Our design is based on a material system consisting of alternating one-dimensionally anisotropic photonic crystal (1D PhC) stacks and half-wave plates. 1D PhC stacks have an angular photonic band gap for p-polarized light and half-wave plates can convert s-polarized light to p-polarized light. Here, by introducing alternating 1D PhC stacks and half-wave plates, we predict that one can achieve a central transmission angle at normal incidence and an angularly selective range of less than 30° across the whole visible spectrum.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Numerical algorithms for water waves with background flow over obstacles and topography

Abstract We present two accurate and efficient algorithms for solving the incompressible, irrotational Euler equations with a free surface in two dimensions with background flow over a periodic, multiply connected fluid domain that includes stationary obstacles and variable bottom topography. One approach is formulated in terms of the surface velocity potential while the other evolves the vortex sheet strength. Both methods employ layer potentials in the form of periodized Cauchy integrals to compute the normal velocity of the free surface, are compatible with arbitrary parameterizations of the free surface and boundaries, and allow for circulation around each obstacle, which leads to multiple-valued velocity potentials but single-valued stream functions. We prove that the resulting second-kind Fredholm integral equations are invertible, possibly after a physically motivated finite-rank correction. In an angle-arclength setting, we show how to avoid curve reconstruction errors that are incompatible with spatial periodicity. We use the proposed methods to study gravity-capillary waves generated by flow around several elliptical obstacles above a flat or variable bottom boundary. In each case, the free surface eventually self-intersects in a splash singularity or collides with a boundary. We also show how to evaluate the velocity and pressure with spectral accuracy throughout the fluid, including near the free surface and solid boundaries. To assess the accuracy of the time evolution, we monitor energy conservation and the decay of Fourier modes and compare the numerical results of the two methods to each other. We implement several solvers for the discretized linear systems and compare their performance. The fastest approach employs a graphics processing unit (GPU) to construct the matrices and carry out iterations of the generalized minimal residual method (GMRES).

Ambrose, David M.↗
DOE OSTI2017

Correlation of precipitate evolution with Vickers hardness in Haynes® 282® superalloy: In-situ high-energy SAXS/WAXS investigation

Here, the aim of this work is to characterise precipitation kinetics in Haynes® 282® superalloy using high-energy Small Angle X-ray Scattering (SAXS) together with Wide Angle X-ray Scattering (WAXS). The phases identified by WAXS include: γ (matrix), γ' (hardening precipitates), MC (metallic carbides), and M 23 C 6 /M 6 C (secondary metallic carbides). The γ'-precipitates are spheroids with a diameter of several nanometres, depending on temperature and aging time. From the SAXS data quantitative parameters such as volume fraction, number density and inter-particle distance were determined and correlated with Vickers microhardness measurements performed ex situ . The strengthening components associated with precipitates and solid solutions were separated using the measured Vickers microhardness and SAXS model parameters. A power law dependence between strengthening attributable to the precipitates and the product of volume fraction and mean precipitate radius was found. The solid solution strengthening component was found to be correlated with the repulsion/diffusion zone width around the precipitates.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Canted antiferromagnetism in the quasi-one-dimensional iron chalcogenide BaFe 2 Se 4

We report the synthesis and physical properties studies of quasi-one-dimensional (quais-1D) iron chalcogenide BaFe 2 Se 4 which shares the FeSe 4 tetrahedra building motif commonly seen in the iron chalcogenide superconductors. A high-quality polycrystalline sample was achieved by solid-state reaction method and characterized by x-ray diffraction, electrical resistivity, magnetic susceptibility, and neutron diffraction measurements. BaFe 2 Se 4 is a narrow gap semiconductor that magnetically orders at ~310 K. Therefore, both neutron powder diffraction results and isothermal M-H loops suggest a canted antiferromagnetic structure where Fe sublattices are antiferromagnetically ordered along the c-axis quasi-1D chain direction, resulting in a net ferromagnetic moment in the perpendicular direction along the a axis with tilted angle of 18.7° towards the b axis.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Punching behavior of BubbleDeck type reinforced concrete slabs

Abstract The BubbleDeck type slab (BD) is a reinforced concrete (RC) flat slab that includes recycled plastic hollow spheres (RPHS) in its core for decreasing its dead weight. However, punching capacity of BD slabs can be a critical aspect, thereby this work is devoted to assess experimentally its punching behavior. An experimental program composed of four real scale prototypes, representative of RC flat slabs in punching loading conditions, was carried out. Two of these slabs are of BD type, while the other two do not include the RPHS system, herein denominated as RC solid slab (SS). The test results show that all the tested slabs failed in punching after the occurrence of yield initiation of the flexural reinforcement. The punching capacity and the deflection at failure of BD type slab has decreased up to 14% and up to 44%, respectively, when compared to the corresponding SS type slab. A relatively small ductility index was obtained (between 1.51 and 2.65). In BD type slabs, the punching failure surface had tendency to propagate through the RPHS, at an inclination angle of about 45°.

Nicácio, Wanderley G.↗
DOE OSTI2021

Patternable Mesoporous Thin Film Quantum Materials via Block Copolymer Self-Assembly: An Emergent Technology?

Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing. Here, we report the preparation of patternable mesoporous niobium carbonitride-type thin film superconductors through spin-coating of a hybrid solution containing an amphiphilic BCP swollen by niobia sol precursors and subsequent thermal processing in combination with photolithography. Spin-coated as-made BCP-niobia hybrid thin films on silicon substrates after optional photolithographic definition are heated in air to produce a porous oxide, and subsequently converted in a multistep process to carbonitrides via treatment with high temperatures in reactive gases including ammonia. Grazing incidence small-angle X-ray scattering suggests the presence of ordered mesostructures in as-made BCP-niobia films without further annealing, consistent with a distorted alternating gyroid morphology that is retained upon thermal treatments. Wide-angle X-ray scattering confirms the synthesis of phase-pure niobium carbonitride nanocrystals with rock-salt lattices within the mesoscale networks. Electrical transport measurements of unpatterned thin films show initial exponential rise in resistivity characteristic of thermal activation in granular systems down to 12.8 K, at which point resistivity drops to zero into a superconducting state. Magnetoresistance measurements determine the superconducting upper critical field to be over 16 T, demonstrating material quality on par with niobium carbonitrides obtained from traditional solid-state synthesis methods. Here. we discuss how such cost-effective and scalable solution-based quantum materials fabrication approaches may be integrated into existing microelectronics processing, promising the emergence of a technology with tremendous academic and industrial potential by combining the capabilities of soft matter self-assembly with quantum materials.

36 MATERIALS SCIENCE↗
DOE OSTI2013

In Situ Study of Atomic Structure Transformations of Pt-Ni Nanoparticle Catalysts during Electrochemical Potential Cycling

When exposed to corrosive anodic electrochemical environments, Pt alloy nanoparticles (NPs) undergo selective dissolution of the less noble component, resulting in catalytically active bimetallic Pt-rich core–shell structures. Structural evolution of PtNi 6 and PtNi 3 NP catalysts during their electrochemical activation and catalysis was studied by in situ anomalous small-angle X-ray scattering to obtain insight in element-specific particle size evolution and time-resolved insight in the intraparticle structure evolution. Ex situ high-energy X-ray diffraction coupled with pair distribution function analysis was employed to obtain detailed information on the atomic-scale ordering, particle phases, structural coherence lengths, and particle segregation. Our studies reveal a spontaneous electrochemically induced formation of PtNi particles of ordered Au 3 Cu-type alloy structures from disordered alloy phases (solid solutions) concomitant with surface Ni dissolution, which is coupled to spontaneous residual Ni metal segregation during the activation of PtNi 6 . Pt-enriched core–shell structures were not formed using the studied Ni-rich nanoparticle precursors. In contrast, disordered PtNi 3 alloy nanoparticles lose Ni more rapidly, forming Pt-enriched core–shell structures with superior catalytic activity. Our X-ray scattering results are confirmed by STEM/EELS results on similar nanoparticles.

Tuaev, Xenia↗
DOE OSTI2019

Novel aqueous amine looping approach for the direct capture, conversion and storage of CO 2 to produce magnesium carbonate

Designing novel integrated chemical pathways for the capture, conversion, and storage of CO 2 is a crucial need for advancing sustainable energy conversion. The accelerated conversion of CO 2 to water-insoluble and stable magnesium carbonate is a thermodynamically downhill route for permanently storing CO 2 . However, a practical constraint of carbon mineralization is the slow kinetics at low CO 2 concentrations. In this study, we investigate a direct integrated mineralization approach, whereby CO 2 , amine solvents (such as monoethanolamine, MEA), water and alkaline Mg-bearing solids are reacted in a slurry reaction environment. About 70% conversion of magnesium oxide to magnesium carbonate was achieved at 50 °C after 3 hours. The looping of amine-bearing solvents between the CO 2 loaded and release states, facilitates the accelerated conversion of magnesium-bearing oxides to magnesium carbonate. Hydrated magnesium carbonate and magnesium hydroxide phases were noted when less than complete conversion of magnesium oxide was achieved. The morphological features were determined using in operando ultra-small and small angle X-ray scattering (USAXS/SAXS) and grazing incidence-small angle X-ray scattering (GI-SAXS) measurements. The proposed pathway is an adaptive, low temperature, single-step approach for the direct capture, conversion and storage of CO 2 . By demonstrating the effectiveness of aqueous alkaline amine looping approach for the accelerated carbon mineralization of MgO, we aim to expand this approach to include heterogeneous alkaline industrial residues such as coal fly ash and steel slag and naturally occurring minerals such as magnesium silicate and calcium silicate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1978

Criteria for the selection of focusing ultrasonic probes

The principles of operation employed in the focusing of a sound field are considered, taking into account the use of solid and liquid coupling media. The focusing limits for a given transducer are investigated. As a diffraction phenomenon, focusing is a function of the system dimensions, the frequency, and the sound velocity. The frequency and the material used for the lenses are in most cases determined in accordance with considerations regarding sound propagation. Changes in the focus are therefore effected mainly by the selection of transducer and lens dimensions. The functions of the focusing factor for a normal immersion probe and a direct contact angle probe are represented in graphs. The deviation of the appropriate parametric values for an ultrasonic probe is illustrated with the aid of examples.

Schlengermann, U.↗
DOE OSTI2014

Three-dimensional periodic supramolecular organic framework ion sponge in water and microcrystals

Self-assembly has emerged as a powerful approach to generating complex supramolecular architectures. Despite there being many crystalline frameworks reported in the solid state, the construction of highly soluble periodic supramolecular networks in a three-dimensional space is still a challenge. In this paper we demonstrate that the encapsulation motif, which involves the dimerization of two aromatic units within cucurbit[8]uril, can be used to direct the co-assembly of a tetratopic molecular block and cucurbit[8]uril into a periodic three-dimensional supramolecular organic framework in water. The periodicity of the supramolecular organic framework is supported by solution-phase small-angle X-ray-scattering and diffraction experiments. Upon evaporating the solvent, the periodicity of the framework is maintained in porous microcrystals. Lastly, as a supramolecular 'ion sponge', the framework can absorb different kinds of anionic guests, including drugs, in both water and microcrystals, and drugs absorbed in microcrystals can be released to water with selectivity.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Characteristics of a four element gyromagnetic nonlinear transmission line array high power microwave source

In this paper, a solid-state four element array gyromagnetic nonlinear transmission line high power microwave system is presented as well as a detailed description of its subsystems and general output capabilities. This frequency agile S-band source is easily adjusted from 2-4 GHz by way of a DC driven biasing magnetic field and is capable of generating electric fields of 7.8 kV/m at 10 m correlating to 4.2 MW of RF power with pulse repetition frequencies up to 1 kHz. Beam steering of the array at angles of ±16.7° is also demonstrated, and the associated general radiation pattern is detailed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

SU-F-T-430: Validation of IBEAM Evo Couch Top for Different Relative Electron Density (RED) Combination During Photon Beam Dose Calculation in Monaco− Treatment Planning System

Purpose: Validation of iBEAM™ evo couch-top for different relative electron density (RED) combination during photon beam dose calculation in Monaco− TPS. Methods: The iBEAM™ evo couch-top has two layers:outer carbon fiber (CF) and inner foam core (FC). To study the beam intensity attenuation of couch-top, measured doses were compared with doses calculated for different REDs. Measurements were performed in solid water phantom with PTW-0.125cc ion-chamber positioned at center of the phantom with 5.3cm thickness slabs placed above and below the chamber. Similarly, in TPS, iBEAM™ evo couch-top was simulated and doses were calculated for different RED combinations (0.2CF-0.2FC, 0.4CF-0.2FC, 0.6CF-0.2FC, 0.8CF-0.2FC, and 1.0CF-0.2FC) by using Monte Carlo dose calculation algorithm in Monaco TPS (V5.1). Doses were measured for every 10 degree gantry angle separation, 10×10cm{sup 2} field size and 6MV photons. Then, attenuation is defined as the ratio of output at posterior gantry angle to output of its opposed anterior gantry angle (e.g.225°/45°). output fluctuation with different gantry angle was within ±0.21%. To confirm above results, dose-planes were measured for five pelvic VMAT plans (360°arc) in PTW two-dimensional array and compared with different calculated dose-planes of above-mentioned couch REDs. Gamma pass rates<1.00) were analyzed for 3%/2mm criteria. Results: Measured and calculated attenuation was in good agreement for the RED combination of 0.2CF-0.2FC and difference was within ±0.515%. However, other density combination showed difference of ±0.9841%, ±1.667%, ±2.9241% and ±2.8832% for 0.4CF-0.2FC, 0.6CF-0.2FC, 0.8CF-0.2FC, and 1.0CF-0.2FC, respectively. Maximum couch-top attenuation was observed at 110°–120° and 240°–250° and decreases linearly as the gantry angle approaches 180°. Moreover, gamma pass rate confirmed the above results and showed maximum pass rate of 96.23% for 0.2CF-0.2FC, whereas others were 95.72%, 95.12%, 94.31% and 93.24%. Conclusion: RED value of 0.2CF-0.2FC was found to be suitable for accurate couch-top modeling for 6MV photon beam Monte Carlo calculations in Monaco TPS.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Falling particle impact erosion testing for particle based CSP systems

CSP systems are currently being examined as an effective method for using solar energy to generate electricity. While much of this research has been conducted using molten salt as the heat transfer medium, in recent years, solid particles have been posited as a cheaper and more energy efficient heat transfer medium for use in CSP systems. Many researchers have looked into the effectiveness of solid particles as a heat transfer medium. However, a concern with the use of particles is that the falling particles will impact various components within the CSP system, such as the hopper, the heat exchanger, and the insulating material, resulting in surface erosion and damage. With repeated impacts from falling particles, material from the surfaces under impact is removed. The degree of erosion depends on whether the substrate is made of brittle or ductile material. Furthermore, factors such as particle shape, size, hardness, concentration, impact angle, particle velocity, and substrate hardness will contribute to the erosion process and determine how much and how quickly erosion will takes place in a system. Three types of erosion will be observed simultaneously: impact erosion from particle impact on receiver, particle storage, and heat exchanger walls, abrasion erosion from particle sliding motion along walls, and attrition erosion as the particles breakdown from particle-to-particle contact and particle-to-wall interactions. It is imperative to understand each of these erosions individually for a more comprehensive understanding and prediction of CSP system durability. In this work, we developed an experimental test setup capable of measuring impact erosion at conditions relevant to 1MW CSP plant. Subsequently, Impact erosion measurements were performed for three different candidate substrate materials at low particle velocities using HSP 40/70 ceramic particles.

14 SOLAR ENERGY↗
DOE OSTI2020

Insights into the Water Transport Mechanism in Polymeric Membranes from Neutron Scattering

Polymeric membranes are ubiquitous in transport applications including gas separation, water desalination, solid-state batteries, and fuel cells. The transport mechanism in certain classes of membranes is well understood. It is generally believed that polymeric membranes used in gas separation follow the solution-diffusion model. However, the transport mechanism in other membranes such as the ones used in water desalination is less clear as both the solution-diffusion and hydrodynamic models have been proposed. In this contribution, we study the structure as well as the water and polymer dynamics of several polymeric membranes using small-angle and quasi-elastic neutron scattering. We demonstrate that on the scale of a few nanometers, water appears to diffuse through a desalination membrane at a rate comparable to bulk water, while water diffuses at a rate that is a factor of 2 slower in an anion-exchange membrane. These results illustrate the importance of studying both the structure and dynamics of membrane materials and have important implications in understanding the transport mechanisms that differentiate the different types of polymeric membranes.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Hyperspectral imaging of minerals in the longwave infrared: the use of laboratory directional-hemispherical reference measurements for field exploration data

Hyperspectral Imaging (HSI) continues to grow as a method for remote detection of vegetation, materials, minerals, and pure chemicals. We have used a longwave infrared (7.7 - 11.8 µm) imaging spectrometer in a static outdoor experiment to collect HSI data from 24 minerals and background materials to determine the efficacy with which HSI can remotely detect and distinguish both pure minerals and mineral mixtures at three solar angles (25°, 35°, and 45° relative to ground) as well as varying backgrounds and other sample effects. Measurements were obtained separately for the minerals and materials mounted directly both on a bare plywood board and a plywood board coated with aluminum foil: 19 powders (3 mixtures and 16 pure mineral powders) held in polyethylene bottle lids as well as 5 samples in rock form were taped directly to the boards. The primary goal of the experiment was to demonstrate that a longwave infrared (LWIR) library of solids and minerals collected as directional-hemispherical reflectance spectra in the laboratory can be used directly for HSI field identification. Prior to the experiment, all 24 mineral/inorganic samples were measured in the laboratory using a Fourier transform infrared spectrometer (FTIR) equipped with a gold-coated IR integrating sphere; the spectra were assimilated as part of a larger reference library of 21 pure minerals, 3 mixtures, and the polyethylene lid. Principal components analysis (PCA) with mean-centering was used in an exploratory analysis of the HSI images and showed that for the aluminum coated board, the first principal component captured the difference between signal that resembled a blackbody and the highly reflective aluminum background. In contrast, principal components PC 2, 3, and 4 were able to discriminate the materials including phosphates, sulfates, silicates, carbonates, and the mixtures. Results from generalized least squares target detection clearly showed that laboratory reference spectra of minerals could be utilized as targets with high fidelity for field detection, both for pure and mixed samples.

47 OTHER INSTRUMENTATION↗