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The Certification of Standard Reference Material 1979: Powder Diffraction Line Profile Standard for Crystallite Size Analysis
No full textThis rather long-standing project has resulted in a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for the analysis of crystallite size from a consideration of powder diffraction line profile broadening. It consists of two zinc oxide powders, one with a crystallite size distribution centered at approximately 15 nm, and a second centered at about 60 nm. These materials display the effects of stacking faults that broaden specific hkl reflections and a slight amount of microstrain broadening. Certification data were collected on the high-resolution powder diffractometer located at beamline 11-BM of the Advanced Photon Source, and on a NIST-built laboratory diffractometer equipped with a Johansson incident beam monochromator and position sensitive detector. Fourier transforms were extracted from the raw data using a modified, two-step profile fitting procedure that addressed the issue of accurate background determination. The mean column lengths, (L)(arex) and (L)(vol), were then computed from the Fourier transforms of the specimen contribution for each reflection. Data were also analyzed with fundamental parameters approach refinements using broadening models to yield (L)(arex) and (L)(vol) values. These values were consistent with the model-independent Fourier transform results; however, small discrepancies were noted for the (L)(arex) values from both machines and both crystallite size ranges. The fundamental parameters approach fits to the laboratory data yielded the certified lattice parameters
Process Monitoring Dataset from the Additive Manufacturing Metrology Testbed (AMMT): Overhang Part X4
No full textX-ray Computed Tomography Data ofAdditive Manufacturing Metrology Testbed (AMMT) Parts: "Overhang Part X4"
No full textNIST Ballistics Toolmark Research Database
No full textIn 2009, a report by the National Academies [1] called into question, amongst other issues, the objectivity of visual toolmark identification by firearms examiners. The National Academies recommended development of objective toolmark identification criteria and error rate estimates. Industry [2,3], academia [4], and government laboratories [5] are pursuing two promising approaches towards this goal: 1) development of mathematical criteria and advanced algorithms for the objective and automated identification and scoring of potential matches, and 2) supplementing traditional reflectance microscopy images with three-dimensional surface topography measurement data.(1) Development of both these approaches to objective toolmark identification are hindered by a lack of access to toolmark datasets that 1) represent the large variety of ballistic toolmarks encountered by firearm examiners, and 2) represent challenging identification scenarios, such as those posed by consecutively manufactured firearms components. It is not economically feasible for individual companies or institutions to generate their own datasets. This makes it difficult for these entities to objectively evaluate their solutions. The NIST Ballistics Toolmark Research Database (NBTRD) removes this hurdle by creating an open access database where 3D topography and 2D image data of bullet, cartridge case and toolmark surfaces could be shared between researchers, whereby new systems, methods, and algorithms could be tested, refined, and compared. The database also provides the representative variety of toolmark data required, ranging from crime lab test fires to test fires conducted using consecutively manufactured barrels, firing pins, slides and other firearm surfaces. The database contains both reflectance microscopy images and three-dimensional surface topography data along with all its relevant metadata. The database enables researchers to test new approaches to objective, mathematics-based, toolmark identification while easing the transition to three-dimensional surface topography data. The database will provide a foundation for a scientific knowledge base on the degree of similarity that can be found between marks made by different firearms and the variability in marks made by an individual firearm. The current, 'fairly limited [1],' knowledge base is a fundamental barrier to the development and validation of objective mathematical similarity criteria, and associated confidence limits, applicable to a broad range of firearms and ammunition brands
Characterization of 3-Dimensional Printing and Casting Materials for use in Computed Tomography and X-ray Imaging Phantoms
No full textImaging phantoms are used to calibrate and validate the performance of medical computed tomography (CT) systems. Many new materials developed for three-dimensional (3D) printing processes may be useful in the direct printing or casting of biomimetic and geometrically accurate CT and X-ray phantoms. The X-ray linear attenuation coefficients of polymer samples were measured to discover materials for use as tissue mimics in phantoms. This study included a cohort of polymer compounds that were tested in cured form. The cohort consisted of 101 standardized polymer samples fabricated from: two-part silicones and polyurethanes used in commercial casting processes; one-part optically cured polyurethanes used in 3D printing; and fused deposition thermoplastics used in 3D printing. The testing was performed with a commercial micro-CT imaging system from 40 kVp to 140 kVp. The X-ray linear coefficients of the samples and human tissues were plotted with error bars to allow the reader to identify suitable mimics. The X-ray linear attenuation coefficients of the tested material samples spanned a wide range of values, with a small number of them overlapping established human tissue mimic values. Twenty 3D printer materials and one castable polyurethane tracked nylon and polymethyl methacrylate (PMMA) as established X-ray mimics for fat. Five 3D printer materials tracked water as an established X-ray mimic for muscle
MICHAEL R. MOLDOVER
No full textTENURE AT NBS/NIST: 1972–2019
INDUCTED into the NIST Gallery of Distinguished Scientists, Engineers, and Administrators: 2020
Birth: 1940, New York City, New York
EDUCATION:
Rensselaer Polytechnic Institute, BS (Physics), 1961
Stanford University, MS (Physics), 1962
Stanford University, PhD (Physics), 1966
CITATION: For creatively advancing standards for measuring thermophysical properties of fluids and for
best-in-the-world measurements of fluid properties, fluid flow, thermodynamic temperature, and the Boltzmann constant resulting in worldwide scientific impact
POSITIONS HELD AT NBS/NIST:
Physicist, Heat Division, Institute for Basic Standards/Chemical Thermodynamics Division, National Measurement Laboratory (NML), 1972-1988
Leader, Fluid Science Group, Thermophysics Division, NML/Process Measurements Division, Chemical Science and Technology Laboratory (CSTL), 1988-2005
Leader, Fluid Metrology Group, Process Measurements Division, CSTL/Sensor Science Division, Physical Measurement Laboratory, 2005-2019
NIST Fellow, 1994-2019
HONORS:
NIST Bronze Medal (1980)
U.S. Department of Commerce Silver Medal (1982 and 2011)
U.S. Department of Commerce Gold Medal (1987)
Samuel Wesley Stratton Award for Research Excellence (1988)
Washington Academy of Sciences Award for Scientific Achievement in the Physical Sciences (1989)
Fellow, Acoustical Society of America (1992)
Fellow, American Physical Society (1994)
Chemical Science and Technology Laboratory Technical Achievement Award (2005)
Presidential Rank Award for Meritorious Service (2009)
Yeram S. Touloukian Award, American Society of Mechanical Engineers (2012)
MEMBERSHIPS:
Acoustical Society of America
American Physical Society
American Society of Mechanical Engineers
PUBLICATIONS:
More than 165 publications and two patents including:
Moldover, M.R., Sengers, J.V., Gammon, R.W., and Hocken, R.J., “Gravity Effects in Fluids Near the Gas-Liquid Critical Point”, Rev. Mod. Phys., 51, 79-99 (1979)
Moldover, M.R. and Cahn, J.W., “An Interface Phase Transition: Complete to Partial Wetting”, Science, 207, 1073-1075 (1980)
Moldover, M.R., Trusler, J.P.M, Edwards, T.J., Mehl, J.B., and Davis, R.S., “Measurement of the Universal Gas Constant R Using a Spherical Acoustic Resonator”, J. of Res. of NBS, 93, 85-144 (1988) AND Phys. Rev. Lett., 60, 249-252, (1988)
Aziz, R.A., Janzen, A.R., and Moldover, M.R., “Ab Initio Calculations for Helium: A Standard for Transport Property Measurements”, Phys. Rev. Lett., 74, 1586-1589 (1995)
Moldover, M.R., Gavioso, R.M., Mehl, J.B., Pitre, L., de Podesta, M., Zhang, J.T., “Acoustic Gas Thermometry”, Metrologia, 51, R1-R19 (2014
The Statistics of Computer Clocks and the Design of Synchronization Algorithms
No full textIn this study, I used standard statistical tools (such as the various forms of the two-sample Allan variance) to characterize the clocks in computers, and I show how the results of this study are used to design algorithms to synchronize the computer clocks. These synchronization algorithms can be used to synchronize the time of a computer to a local reference clock or to a remote server. The algorithms by themselves are not intended to be a simple replacement for software that implements the Network Time Protocol (NTP) or any other similar application. Instead, they describe the statistical principles that should be used to design an algorithm to synchronize any computer clock by using data from any external reference received in any format. These algorithms have been used to synchronize the clocks of the computers that support the Internet Time Service operated by the National Institute of Standards and Technology (NIST), and I illustrate the performance of the algorithm with real-time data from these servers. In addition to presenting the design principles of the algorithm, I illustrate the principles with two specific examples: synchronizing a computer clock to a local reference signal, and the design of a synchronization process that is based on time-difference data received from a remote server over the public Internet. The message exchange between the local system and the remote server in this configuration is realized in NTP format, but that is not a fundamental requirement
A Concept for Three-Dimensional Particle Metrology Based on Scanning Electron Microscopy and Structure-from-Motion Photogrammetry
No full textScanning electron microscopy (SEM) has been frequently used for size and shape measurements of particles. SEM images offer two-dimensional (2D) information about a particle's lateral dimensions. Unfortunately, information about the particle's three-dimensional (3D) size and shape remains unavailable. To resolve this issue, I propose a new concept in SEM: 3D particle metrology obtained by applying structure-from-motion (SfM) algorithms to multiple rotational SEM images of particles deposited onto a cylindrical substrate to generate a 3D model from which size and shape information can be extracted. Particles can have any size that is suitable for SEM imaging. SEM images of the sample can be acquired from 0 degrees to 360 degrees using a rotational-tip SEM substage. Here, I will discuss the concept and, for clarity, illustrate it with aquarium gravel particles that are glued onto a craft roll and imaged optically before generating the 3D model of that handmade craft. Future work will include the experimental SEM realization, as well as further development of the SfM algorithms. In my view, this proposed concept may become an integral part of SEM-based particle metrology
Hylleraas-Configuration Interaction (Hy-CI) Non-Relativistic Energies for the 3 1S, 4 1S, 5 1S, 6 1S, and 7 1S Excited States of the Beryllium Atom
No full textIn a previous work Sims and Hagstrom [J Chem Phys 140,224312(2014)] reported Hylleraas-configuration interaction (Hy-CI) method variational calculations for the S-1 ground states of the beryllium isoelectronic sequence with an estimated accuracy of 10 to 20 nanohartrees (nHa). In this work the calculations have been extended to the five higher states of the neutral beryllium atom, 3 S-1, 4 S-1, 5 S-1, 6 S-1 and 7 S-1. The best non-relativistic energies obtained for these states are -14.4182 4034 6, -14.3700 8789 0, -14.3515 1167 6, -14.3424 0357 8, and -14.3372 6649 96 Ha, respectively. The 6 S-1 result is superior to the known reference energy for that state, while for the 7 S-1 state there is no other comparable calculation