EXPRESS: Spectral Considerations for Standoff Infrared Detection of RDX on Reflective Aluminum

2021 ◽  
pp. 000370282110538
Author(s):  
Kevin J Major ◽  
Jas Sanghera ◽  
Mikella E. Farrell ◽  
Ellen L Holthoff ◽  
Paul M Pellegrino ◽  
...  
Keyword(s):  
Surface Concentration ◽  
Thin Layers ◽  
Infrared Detection ◽  
Aluminum Surface ◽  
Material System ◽  
Spectral Signatures ◽  
Spectral Changes ◽  
Standoff Detection ◽  
Infrared Spectrometer ◽  
Specific Material

This paper examines infrared spectroscopic effects for the standoff detection of an explosive material, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), inkjet printed on an aluminum surface. Results of a spectroscopic study are described, using multiple optical setups. These setups were selected to explore how variations in the angles of incidence and collection from the surface of the material result in corresponding variations in the spectral signatures. The goal of these studies is to provide an understanding of these spectral changes, since it affects standoff detection of hazardous materials on a reflective substrate. We demonstrate that variations in spectral effects are dependent on the relative surface concentration of the deposited RDX. We also show that it is reasonable to use spectroscopic data collected in a standard laboratory infrared spectrometer outfitted with a variable angle reflectometer set at 0 as reference spectra for data collected in a standoff configuration. These results are important to provide a systematic approach to understanding IR spectra collection using standoff systems in the field, and to allow for comparison between such data, and data collected in the laboratory. Though the precise results are constrained to a specific material system (thin layers on a reflective substrate), the approach and general discussion provided are applicable to a broad range of IR standoff sensing techniques and applications.

scholarly journals Fabrication and Characterization of Electrospun Pristine and Fluorescent Composite Poly (acrylic acid) Ultra-Fine Fibers

2012 ◽  
Vol 7 (2_suppl) ◽  
pp. 155892501200702 ◽  
Author(s):  
Jennifer S. Atchison ◽  
Caroline L. Schauer
Keyword(s):  
Acrylic Acid ◽  
Charged Droplet ◽  
Material System ◽  
Composite Fibers ◽  
Fine Fiber ◽  
Specific Material ◽  
Nanofabrication Technique ◽  
Fibrous Assemblies ◽  
Small Clusters ◽  
Poly Acrylic Acid

Electrospinning is a facile nanofabrication technique that produces fibrous assemblies of ultra-fine fibers, 20–1000 nm in diameter, from a charged droplet of spinning solution. Optimization of the fiber diameter of a specific material system is dependent on the solution and process variables. The electrospinning parameters for poly (acrylic acid) (PAA), a synthetic polyelectrolyte, were systematically investigated and consistent nanofiber diameters with uniform morphology were achieved. The optimization matrix included several solvent systems including ethanol, aqueous NaCl and aqueous NaOH. Optimized spinning parameters were then applied to electrospinning fluorescent fibrous assembles of quantum dot-PAA ultra-fine fiber composites. Ultrafine composite fibers were prepared by electrospinning aqueous solutions of 6wt% PAA loaded with 0.05, 0.10, 0.15 and 0.20%v/v, carboxylic acid functionalized CdSe/ZnS nanoparticles (SNPs). The resulting composite fibers exhibited uniform fiber morphologies with increasing fiber diameters corresponding to increasing SNP loading. Fluorescence micrographs reveal luminescent fibers with evenly distributed fluorophores in the higher loaded samples. Moreover, laser excited fibers manifest SNP intermittency correlated with small clusters and single SNPs suggesting excellent dispersion in the PAA matrix.

scholarly journals Raman Spectroscopy as Noninvasive Method of Diagnosis of Pediatric Onset Inflammatory Bowel Disease

2020 ◽  
Vol 10 (19) ◽  
pp. 6974
Author(s):  
Giuseppe Acri ◽  
Valentina Venuti ◽  
Stefano Costa ◽  
Barbara Testagrossa ◽  
Salvatore Pellegrino ◽  
...  
Keyword(s):  
Operating Characteristic ◽  
Spectroscopic Method ◽  
Duodenal Biopsy ◽  
Noninvasive Method ◽  
Spectral Signatures ◽  
Spectral Changes ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
Cellular Modifications ◽  
Pediatric Onset

We propose here a spectroscopic method to diagnose and differentiate inflammatory bowel diseases (IBD), such as ulcerative colitis (UC) and Crohn’s disease (CD) with pediatric onset, in a complete noninvasive way without performing any duodenal biopsy. In particular, the Raman technique was applied to proteic extract from fecal samples in order to achieve information about molecular vibrations that can potentially furnish spectral signatures of cellular modifications occurring as a consequence of specific pathologic conditions. The attention was focused on the investigation of the amide I region, quantitatively accounting the spectral changes in the secondary structures by applying deconvolution and curve-fitting. Inflammation is found to give rise to a significant increasing of the nonreducible (trivalent)/reducible (divalent) cross-linking ratio R of the protein network. This parameter revealed an excellent marker in order to distinguish IBD subjects from non-IBD ones, and, among IBD patients, to differentiate between UC and CD. The proposed methodology was validated by statistical analysis using the receiver operating characteristic (ROC) curve.

Semiconductor-to-metal attachment with silver-filled TPI bondlines

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000064-000067
Author(s):  
Jim Fraivillig ◽  
Richard Koba ◽  
Kent Hutchings
Keyword(s):  
Adhesive Layer ◽  
Thin Layers ◽  
Aluminum Surface ◽  
Semiconductor Surface ◽  
Minimal Amount ◽  
Metal Foil ◽  
Thermal Impedance ◽  
High Concentration ◽  
Wide Range ◽  
Semiconductor Packages

In the attachment of semiconductor chips and submounts to metal heat sinks, bondlines utilizing silver-filled thermoplastic polyimide adhesive (TPI) are very durable across a wide range of environmental conditions (thermal, physical, chemical, radiation). TPI bondlines can withstand an extreme CTE-mismatch between the laminated materials, and have excellent bonding with adhesive-layer thicknesses down to only a few microns. To provide electrical conductivity and enhance thermal conductivity, the TPI bondline can be compounded with a high concentration of silver particles, and retain durability and adhesion. There are two general constructions of silver-filled TPI bondlines:Bondfoil – thin layers of silver-filled B-staged TPI coatings on either side of a metal carrier/substrate. The thickness of the (cured) TPI coatings would be 2–10 μm/side. TPI-priming (B- or C-staged; partially or fully cured) of a semiconductor surface may be required.TPI coating only – thin layers of silver-filled TPI polymer (1–3 μm/surface; B- or C-staged) on the interface surfaces to be bonded. A minimal amount of A-staged TPI (liquid: polymer in solvent) may be added to the bondline construction to optimize surface wetting during lamination.The ultimate in robustness and thinness, silver-filled TPI bondlines can provide:Continuous operation at 350°C, as well as temporary exposure to 450°C. Thermogravimetric analysis (TGA) of the TPI polymer shows that degradation does not start until well above 500°C. [See opposite.]Thermal shock durability -- the CTE-mismatched TPI bondline between silicon and aluminum can survive repeated thermal shocks with a ΔT of 300–400°C.Thermal impedance as low as 0.06 °C-cm2/W (0.01°C-in2/W) when using a silver-filled TPI bondfoil, and about 0.01 °C-cm2/W (0.002°C-in2/W) when using just silver-filled TPI coatings on the interface surfaces (no metal foil). In both constructions, the thermal impedance includes all interface resistances.Shear strength of 10 MPa to an aluminum surface and 1–2 MPa to silicon. These features make TPI bondlines ideal for demanding, CTE-mismatched semiconductor packages. As opposed to cross-linked thermoset bondlines -- which are brittle, especially when highly filled -- thermoplastic polyimide bondlines remain ductile and resist cracking, even when highly stressed.

Infrared Photoconductivity and Photoluminescence from InAs/Ga1–xInxSb Strained-Layer Superlattices

1990 ◽  
Vol 198 ◽  
Author(s):  
R. H. Miles ◽  
D. H. Chow ◽  
T. C. Mcgill
Keyword(s):  
Infrared Detectors ◽  
Far Infrared ◽  
Thin Layers ◽  
Band Gaps ◽  
Infrared Detection ◽  
Strained Layer ◽  
Energy Gaps ◽  
Theoretical Predictions ◽  
Spectrally Resolved ◽  
Strained Layer Superlattices

ABSTRACTWe have examined spectrally resolved photoconductivity and photoluminescence from InAs/Ga1–xInxSb strained-layer superlattices, which have been proposed as infrared detectors in the 8-14 μm region. Our measurements indicate that the energy gaps of the strained–layer superlattices are substantially smaller than those of InAs/GaSb superlattices with similar layer thicknesses, in agreement with previous theoretical predictions. Measurements on InAs/Ga1–xInxSb superlattices with x=0 and 0.25 and layer thicknesses of 25 – 45 A indicate superlattice band gaps of 3 – 15 μm, in excellent agreement with gaps calculated by a two band k · p model. Our results demonstrate that far-infrared energy gaps are compatible with the thin layers necessary for strong optical absorption in type-IT superlattices, and suggest that InAs/Ga1–xInxSb superlattices are promising candidates for far-infrared detection.

scholarly journals Spectral Identification of Disease in Weeds Using Multilayer Perceptron with Automatic Relevance Determination

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2770 ◽  
Author(s):  
Afroditi Tamouridou ◽  
Xanthoula Pantazi ◽  
Thomas Alexandridis ◽  
Anastasia Lagopodi ◽  
Giorgos Kontouris ◽  
...  
Keyword(s):  
Biological Control ◽  
Multilayer Perceptron ◽  
Near Infrared ◽  
Systemic Infection ◽  
Principal Component ◽  
Identification Process ◽  
Spectral Signatures ◽  
Automatic Relevance Determination ◽  
Infrared Spectrometer ◽  
Control Application

Microbotryum silybum, a smut fungus, is studied as an agent for the biological control of Silybum marianum (milk thistle) weed. Confirmation of the systemic infection is essential in order to assess the effectiveness of the biological control application and assist decision-making. Nonetheless, in situ diagnosis is challenging. The presently demonstrated research illustrates the identification process of systemically infected S. marianum plants by means of field spectroscopy and the multilayer perceptron/automatic relevance determination (MLP-ARD) network. Leaf spectral signatures were obtained from both healthy and infected S. marianum plants using a portable visible and near-infrared spectrometer (310–1100 nm). The MLP-ARD algorithm was applied for the recognition of the infected S. marianum plants. Pre-processed spectral signatures served as input features. The spectra pre-processing consisted of normalization, and second derivative and principal component extraction. MLP-ARD reached a high overall accuracy (90.32%) in the identification process. The research results establish the capacity of MLP-ARD to precisely identify systemically infected S. marianum weeds during their vegetative growth stage.

scholarly journals Electrocatalytic Activity of Galvanostatically Deposited Ni thin Films for Methanol Electrooxidation

2019 ◽  
Author(s):  
Maria Paula Salinas-Quezada ◽  
D. Alfonso Crespo-Yapur ◽  
Abraham Cano-Marquez ◽  
Marcelo Videa
Keyword(s):  
Electrocatalytic Activity ◽  
Noble Metals ◽  
Supporting Electrolyte ◽  
Surface Concentration ◽  
Thin Layers ◽  
Synthetic Methods ◽  
Constant Current ◽  
Direct Alcohol Fuel Cells ◽  
Oxidation Of Methanol ◽  
Polycrystalline Gold

Nickel and nickel-based nanomaterials are an attractive choice to replace noble metals as electrocatalyst in alkaline direct alcohol fuel cells (DAFCs) owing to their lower cost and suitable electrocatalytic activity. Among the different synthetic methods available for the production of nanostructured materials, galvanostatic electrodeposition offers a fast and simple means of fabricating active electrodes. Therefore, thin-layers of nickel were electrodeposited onto polycrystalline gold electrodes using constant current pulses from an electrolyte containing 50 mM NiSO4. The electrocatalytic properties of the nickel nanostructures in alkaline medium, in which the catalytic species NiOOH is formed, were evaluated through cyclic voltammetry in 0.5 M methanol + 1 M KOH. The effects of current density pulse and the presence of sulfate or chloride anions in the supporting electrolyte on the electrocatalytic activity of the deposits were studied using Ni(OH)2 surface concentration, Gamma, and electrocatalytic intensity, EI, as performance parameters. It was found that highest electrolcatalytic activities were obtained when using current densities pulses close to 4.0 mA/cm2 in the presence of sulfates. It was found that the presence of sulfates leads to a strong correlation between the electrocatalytic activity for the oxidation of methanol and the surface concentration of Ni(OH)2.

Novel Glass-free LTCC Material co-fired with Cupper-Electrodes

2016 ◽  
Vol 2016 (CICMT) ◽  
pp. 000130-000135
Author(s):  
Yasutaka Sugimoto ◽  
Tsuyoshi Katsube ◽  
Machiko Motoya ◽  
Yuki Takemori ◽  
Yoichi Moriya ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Rf Circuits ◽  
Glass Frit ◽  
Thin Layers ◽  
Material System ◽  
Low Oxygen ◽  
High Mechanical Strength ◽  
Microwave Electronic ◽  
Electric Loss ◽  
Dielectric And Mechanical Properties

Abstract Low Temperature Co-fired Ceramics (LTCC) have excellent high-frequency characteristics and have widely been used for microwave electronic components. By lowering the sintering temperature of the ceramics used as insulating layers, LTCC was co-fired with a high-conductivity wiring conductor, such as Cu or Ag. LTCC substrate has been expected as one of the most promising technologies to realize miniaturization of RF circuits in the field of wireless communications. There is no limitation to demand for further downsizing of RF circuits, suppression of electric loss and high mechanical strength of the substrate. However, conventional LTCC materials for substrates contain glass frit which causes defects, such as pores or cracks, and low mechanical strength. In this work, we have developed a novel LTCC material system BaO-Al2O3-SiO2-MnO-TiO2, without any glass frits. The material was co-fired with cupper electrodes, which have low resistivity and show less diffusion than silver in LTCC, under a low-oxygen partial pressure atmosphere (mixture of N2 and H2) at 980°C. Thin layers (8μm) of the material showed high insulating resistivity and reliability due to few defects, such as pores, in LTCC. Its dielectric and mechanical properties were measured as 6.8 (low-εr), 350 at 3GHz (high-Q-value) and 341MPa (high mechanical strength) respectively. This LTCC material will contribute to further miniaturizing of microwave applications and integration of passive elements.

Spectral properties of the earth’s contribution to seismic resolution

Geophysics ◽  
1995 ◽  
Vol 60 (1) ◽  
pp. 241-251 ◽  
Author(s):  
David A. Okaya
Keyword(s):  
Thin Layers ◽  
Impulse Responses ◽  
Time Frequency ◽  
Spectral Signatures ◽  
Seismic Resolution ◽  
Reflectivity Spectra ◽  
Frequency Transformations ◽  
Definition Of ◽  
And Behavior ◽  
Amplitude Versus

Layered reflectivity sequences have spectral signatures (impulse responses) in accordance with time‐frequency transformations. These signatures are filtered by a source under the convolutional definition of a seismogram. Spectral signatures of wedge models indicate that thin layers have preferred source bandwidths needed to produce either a tuned reflection or separate interface reflections. Sources that do not include these preferred frequencies do not produce optimally imaged reflections. Criteria for the classic tuning thickness and behavior of source‐dependent amplitude versus time‐thickness crossplots are better understood in relation to the reflectivity impulse response. Reflectivity spectra indicate that higher‐order tuning thicknesses exist. Earth reflectivity also prevents the return of certain source frequencies; this behavior may possibly be an interpretive tool.

scholarly journals Studying the Composition and Mineralogy of the Hermean Surface with the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) for the BepiColombo Mission: An Update

2020 ◽  
Vol 216 (6) ◽  
Author(s):  
H. Hiesinger ◽  
◽  
J. Helbert ◽  
G. Alemanno ◽  
K. E. Bauch ◽  
...  
Keyword(s):  
Wavelength Region ◽  
Thermal Infrared ◽  
Scientific Output ◽  
Power Performance ◽  
Time Saving ◽  
Spectral Signatures ◽  
Infrared Spectrometer ◽  
Multiple Levels ◽  
Better Than ◽  
Weathering Effects

AbstractLaunched onboard the BepiColombo Mercury Planetary Orbiter (MPO) in October 2018, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is on its way to planet Mercury. MERTIS consists of a push-broom IR-spectrometer (TIS) and a radiometer (TIR), which operate in the wavelength regions of 7-14 μm and 7-40 μm, respectively. This wavelength region is characterized by several diagnostic spectral signatures: the Christiansen feature (CF), Reststrahlen bands (RB), and the Transparency feature (TF), which will allow us to identify and map rock-forming silicates, sulfides as well as other minerals. Thus, the instrument is particularly well-suited to study the mineralogy and composition of the hermean surface at a spatial resolution of about 500 m globally and better than 500 m for approximately 5-10% of the surface. The instrument is fully functional onboard the BepiColombo spacecraft and exceeds all requirements (e.g., mass, power, performance). To prepare for the science phase at Mercury, the team developed an innovative operations plan to maximize the scientific output while at the same time saving spacecraft resources (e.g., data downlink). The upcoming fly-bys will be excellent opportunities to further test and adapt our software and operational procedures. In summary, the team is undertaking action at multiple levels, including performing a comprehensive suite of spectroscopic measurements in our laboratories on relevant analog materials, performing extensive spectral modeling, examining space weathering effects, and modeling the thermal behavior of the hermean surface.

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