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Journal of Research of the National Institute of Standards and Technology

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https://www.readbyqxmd.com/read/26958454/potential-stable-low-permeation-rate-standard-based-on-micro-machined-silicon
#1
Adrian Verwolf, Chris Poling, Nick Barbosa, Grady White, Nikki Rentz
Silicon wafers with micro-machined holes were evaluated for use as low-permeation-rate standard artifacts. Accuracy, stability, and reliability were assessed. Two independent experimental techniques for evaluating permeation were used: chilled mirror hygrometer and mass loss. The wafers exhibited a well-defined linear relationship between hole area and resultant water partial pressure for both techniques, although the mass loss curve exhibited a constant vertical offset from the hygrometer curve, attributed to water loss through the O-ring seal...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958453/certification-of-nist-room-temperature-low-energy-and-high-energy-charpy-verification-specimens
#2
Enrico Lucon, Chris N McCowan, Ray L Santoyo
The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of -40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at -40 °C...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958452/morphological-and-electrical-characterization-of-mwcnt-papers-and-pellets
#3
Elisabeth Mansfield, Ari Feldman, Ann N Chiaramonti, John Lehman, Alexandra E Curtin
Six types of commercially available multiwall carbon nanotube soot were obtained and prepared into buckypapers by pellet pressing and by filtration into a paper. These samples were evaluated with respect to thickness, compressibility and electrical conductivity. DC conductivity results by two-point and four-point (van der Pauw) measurement methods as a function of preparation parameters are presented. Topology was investigated qualitatively by way of scanning electron microscopy and helium ion microscopy and from this, some generalizations about the nanotube structural properties and manufacturing technique with respect to conductivity are given...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958451/toward-continuous-gps-carrier-phase-time-transfer-eliminating-the-time-discontinuity-at-an-anomaly
#4
Jian Yao, Judah Levine, Marc Weiss
The wide application of Global Positioning System (GPS) carrier-phase (CP) time transfer is limited by the problem of boundary discontinuity (BD). The discontinuity has two categories. One is "day boundary discontinuity," which has been studied extensively and can be solved by multiple methods [1-8]. The other category of discontinuity, called "anomaly boundary discontinuity (anomaly-BD)," comes from a GPS data anomaly. The anomaly can be a data gap (i.e., missing data), a GPS measurement error (i.e., bad data), or a cycle slip...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958450/a-journey-in-standard-development-the-core-manufacturing-simulation-data-cmsd-information-model
#5
Yung-Tsun Tina Lee
This report documents a journey "from research to an approved standard" of a NIST-led standard development activity. That standard, Core Manufacturing Simulation Data (CMSD) information model, provides neutral structures for the efficient exchange of manufacturing data in a simulation environment. The model was standardized under the auspices of the international Simulation Interoperability Standards Organization (SISO). NIST started the research in 2001 and initiated the standardization effort in 2004. The CMSD standard was published in two SISO Products...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958449/rapid-prototyping-of-nanofluidic-slits-in-a-silicone-bilayer
#6
Thomas P Kole, Kuo-Tang Liao, Daniel Schiffels, B Robert Ilic, Elizabeth A Strychalski, Jason G Kralj, J Alexander Liddle, Anatoly Dritschilo, Samuel M Stavis
This article reports a process for rapidly prototyping nanofluidic devices, particularly those comprising slits with microscale widths and nanoscale depths, in silicone. This process consists of designing a nanofluidic device, fabricating a photomask, fabricating a device mold in epoxy photoresist, molding a device in silicone, cutting and punching a molded silicone device, bonding a silicone device to a glass substrate, and filling the device with aqueous solution. By using a bilayer of hard and soft silicone, we have formed and filled nanofluidic slits with depths of less than 400 nm and aspect ratios of width to depth exceeding 250 without collapse of the slits...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958448/an-implementation-of-the-fundamental-parameters-approach-for-analysis-of-x-ray-powder-diffraction-line-profiles
#7
Marcus H Mendenhall, Katharine Mullen, James P Cline
This work presents an open implementation of the Fundamental Parameters Approach (FPA) models for analysis of X-ray powder diffraction line profiles. The original literature describing these models was examined and code was developed to allow for their use within a Python based least squares refinement algorithm. The NIST interest in the FPA method is specific to its ability to account for the optical aberrations of the powder diffraction experiment allowing for an accurate assessment of lattice parameter values...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958447/smart-electronic-laboratory-notebooks-for-the-nist-research-environment
#8
Richard S Gates, Mark J McLean, William A Osborn
Laboratory notebooks have been a staple of scientific research for centuries for organizing and documenting ideas and experiments. Modern laboratories are increasingly reliant on electronic data collection and analysis, so it seems inevitable that the digital revolution should come to the ordinary laboratory notebook. The most important aspect of this transition is to make the shift as comfortable and intuitive as possible, so that the creative process that is the hallmark of scientific investigation and engineering achievement is maintained, and ideally enhanced...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958446/the-optics-and-alignment-of-the-divergent-beam-laboratory-x-ray-powder-diffractometer-and-its-calibration-using-nist-standard-reference-materials
#9
James P Cline, Marcus H Mendenhall, David Black, Donald Windover, Albert Henins
The laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958445/long-term-stability-of-one-inch-condenser-microphones-calibrated-at-the-national-institute-of-standards-and-technology
#10
Randall P Wagner, William F Guthrie
The devices calibrated most frequently by the acoustical measurement services at the National Institute of Standards and Technology (NIST) over the 50-year period from 1963 to 2012 were one-inch condenser microphones of three specific standard types: LS1Pn, LS1Po, and WS1P. Due to its long history of providing calibrations of such microphones to customers, NIST is in a unique position to analyze data concerning the long-term stability of these devices. This long history has enabled NIST to acquire and aggregate a substantial amount of repeat calibration data for a large number of microphones that belong to various other standards and calibration laboratories...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958444/development-of-an-ultra-pure-carrier-free-209-po-solution-standard
#11
R Collé, R P Fitzgerald, L Laureano-Perez
Ultra-pure, carrier-free (209)Po solution standards have been prepared and standardized for their massic alpha-particle emission rate. The standards, which will be disseminated by the National Institute of Standards and Technology (NIST) as Standard Reference Material SRM 4326a, have a mean mass of (5.169 ± 0.003) g of a solution of polonium in nominal 2.0 mol▪L(-1) HCl (having a solution density of (1.032 ± 0.002) g▪ mL(-1) at 20 °C) that are contained in 5 mL, flame-sealed, borosilicate glass ampoules...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958443/a-simple-and-fast-spline-filtering-algorithm-for-surface-metrology
#12
Hao Zhang, Daniel Ott, John Song, Mingsi Tong, Wei Chu
Spline filters and their corresponding robust filters are commonly used filters recommended in ISO (the International Organization for Standardization) standards for surface evaluation. Generally, these linear and non-linear spline filters, composed of symmetric, positive-definite matrices, are solved in an iterative fashion based on a Cholesky decomposition. They have been demonstrated to be relatively efficient, but complicated and inconvenient to implement. A new spline-filter algorithm is proposed by means of the discrete cosine transform or the discrete Fourier transform...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958442/sagrad-a-program-for-neural-network-training-with-simulated-annealing-and-the-conjugate-gradient-method
#13
Javier Bernal, Jose Torres-Jimenez
SAGRAD (Simulated Annealing GRADient), a Fortran 77 program for computing neural networks for classification using batch learning, is discussed. Neural network training in SAGRAD is based on a combination of simulated annealing and Møller's scaled conjugate gradient algorithm, the latter a variation of the traditional conjugate gradient method, better suited for the nonquadratic nature of neural networks. Different aspects of the implementation of the training process in SAGRAD are discussed, such as the efficient computation of gradients and multiplication of vectors by Hessian matrices that are required by Møller's algorithm; the (re)initialization of weights with simulated annealing required to (re)start Møller's algorithm the first time and each time thereafter that it shows insufficient progress in reaching a possibly local minimum; and the use of simulated annealing when Møller's algorithm, after possibly making considerable progress, becomes stuck at a local minimum or flat area of weight space...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958441/an-improved-algorithm-of-congruent-matching-cells-cmc-method-for-firearm-evidence-identifications
#14
Mingsi Tong, John Song, Wei Chu
The Congruent Matching Cells (CMC) method was invented at the National Institute of Standards and Technology (NIST) for firearm evidence identifications. The CMC method divides the measured image of a surface area, such as a breech face impression from a fired cartridge case, into small correlation cells and uses four identification parameters to identify correlated cell pairs originating from the same firearm. The CMC method was validated by identification tests using both 3D topography images and optical images captured from breech face impressions of 40 cartridge cases fired from a pistol with 10 consecutively manufactured slides...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958440/on-the-stability-of-rotating-drops
#15
A K Nurse, S R Coriell, G B McFadden
We consider the equilibrium and stability of rotating axisymmetric fluid drops by appealing to a variational principle that characterizes the equilibria as stationary states of a functional containing surface energy and rotational energy contributions, augmented by a volume constraint. The linear stability of a drop is determined by solving the eigenvalue problem associated with the second variation of the energy functional. We compute equilibria corresponding to both oblate and prolate shapes, as well as toroidal shapes, and track their evolution with rotation rate...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958439/an-areal-isotropic-spline-filter-for-surface-metrology
#16
Hao Zhang, Mingsi Tong, Wei Chu
This paper deals with the application of the spline filter as an areal filter for surface metrology. A profile (2D) filter is often applied in orthogonal directions to yield an areal filter for a three-dimensional (3D) measurement. Unlike the Gaussian filter, the spline filter presents an anisotropic characteristic when used as an areal filter. This disadvantage hampers the wide application of spline filters for evaluation and analysis of areal surface topography. An approximation method is proposed in this paper to overcome the problem...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958438/design-and-operation-of-an-optically-accessible-modular-reactor-for-diagnostics-of-thermal-thin-film-deposition-processes
#17
W A Kimes, B A Sperling, J E Maslars
The design and operation of a simple, optically-accessible modular reactor for probing thermal thin film deposition processes, such as atomic layer deposition processes (ALD) and chemical vapor deposition (CVD), is described. This reactor has a nominal footprint of 225 cm(2) and a mass of approximately 6.6 kg, making it small enough to conveniently function as a modular component of an optical train. The design is simple, making fabrication straightforward and relatively inexpensive. Reactor operation is characterized using two infrared absorption measurements to determine exhaust times for tetrakis(dimethylamino)titanium and water, proto-typical ALD precursors, in a pressure and flow regime commonly used for ALD...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958437/revision-of-the-nist-standard-for-223-ra-new-measurements-and-review-of-2008-data
#18
B E Zimmerman, D E Bergeron, J T Cessna, R Fitzgerald, L Pibida
After discovering a discrepancy in the transfer standard currently being disseminated by the National Institute of Standards and Technology (NIST), we have performed a new primary standardization of the alpha-emitter (223)Ra using Live-timed Anticoincidence Counting (LTAC) and the Triple-to-Double Coincidence Ratio Method (TDCR). Additional confirmatory measurements were made with the CIEMAT-NIST efficiency tracing method (CNET) of liquid scintillation counting, integral γ-ray counting using a NaI(Tl) well counter, and several High Purity Germanium (HPGe) detectors in an attempt to understand the origin of the discrepancy and to provide a correction...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958436/findings-and-recommendations-from-the-nist-workshop-on-alternative-fuels-and-materials-biocorrosion
#19
Elisabeth Mansfield, Jeffrey W Sowards, Wendy J Crookes-Goodson
In 2013, the Applied Chemicals and Materials Division of the National Institute of Standards and Technology (NIST) hosted a workshop to identify and prioritize research needs in the area of biocorrosion. Materials used to store and distribute alternative fuels have experienced an increase in corrosion due to the unique conditions caused by the presence of microbes and the chemistry of biofuels and biofuel precursors. Participants in this workshop, including experts from the microbiological, fuel, and materials communities, delved into the unique materials and chemical challenges that occur with production, transport, and storage of alternative fuels...
2015: Journal of Research of the National Institute of Standards and Technology
https://www.readbyqxmd.com/read/26958435/report-on-pairing-based-cryptography
#20
Dustin Moody, Rene Peralta, Ray Perlner, Andrew Regenscheid, Allen Roginsky, Lily Chen
This report summarizes study results on pairing-based cryptography. The main purpose of the study is to form NIST's position on standardizing and recommending pairing-based cryptography schemes currently published in research literature and standardized in other standard bodies. The report reviews the mathematical background of pairings. This includes topics such as pairing-friendly elliptic curves and how to compute various pairings. It includes a brief introduction to existing identity-based encryption (IBE) schemes and other cryptographic schemes using pairing technology...
2015: Journal of Research of the National Institute of Standards and Technology
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