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Comparison of Models for Heat Transfer in High-Density Fibrous Insulation
No full textThis study evaluated different models for calculating the effective thermal conductivity of fibrous insulation by comparing predicted values with certified values of Standard Reference Material 1450c, Fibrous Glass Board. This comparison involved the coupled effects of radiation and conduction heat transfer. To support these comparisons, the fiber diameter distribution was measured using X-ray computed tomography, and this distribution was used in several heat transfer models considered in this paper. For the evaluation of the radiative heat transfer, the diffusion approximation, the Schuster-Schwarzschild approximation, and the Milne-Eddington approximation were considered. The conduction of the gas and the fibers was treated by the kinetic theory and a semi-empirical model, respectively. Two models were considered for the evaluation of the radiative properties: the large specular reflecting approach and the application of Mie theory for media composed of infinite cylinders
Sharon A. Shaffer
No full textSharon A. Shaffer
NBS/NIST: 1971-2006
INDUCTED: 2019
CITATION: For decades of outstanding management of NIST-wide outreach efforts to industry and other stakeholders through publications, websites, and exhibits in ways that enhanced NIST’s reputation for integrity and excellence.
Birth: 1945, San Rafael, California
EDUCATION:
University of Rhode Island, BS (Textiles and Clothing), 1967
POSITIONS HELD AT NBS/NIST:
Technical Publications Writer-editor, Office of Information Activities, Office of the Associate Director for Information Programs, 1971-1979
Leader, Editorial Services Unit, Public Affairs Division, Office of the Director of Administration, 1979-1995
Leader, Communications and Inquiries Group, Public and Business Affairs Division, Office of the Director of Administration/CFO, 1995-2004
Chief, Public and Business Affairs Office, Office of the Chief of Staff, 2004-2006
SIGNIFICANCE OF WORK:
For more than three decades, Shaffer guided a full spectrum of communications created by Public Affairs to explain the substance and importance of NBS/NIST's work to industry leaders, policymakers, academic researchers, and broad sectors of the public. She led these communications in increasingly responsible management positions before retiring in 2006. Shaffer worked collaboratively with laboratory and other program managers and staff spreading the word about the agency’s work and how other organizations could collaborate with NBS/NIST and make the best use of its products, services, and information. She was responsible for managing publications, websites, conferences, exhibits, and audiovisual programs describing the value and details of NBS/NIST’s work and developing communications aimed at members of Congress and other senior policymakers, industry leaders, academic experts and NIST staff.
Shaffer made major contributions to multiple Commerce Department and administration publications and events that spotlighted the work of NBS/NIST. In addition to overseeing scores of periodicals and special publications, Shaffer was primary editor for a series explaining by text and creative graphics the need for new and improved facilities, including the Advanced Measurement Laboratory complex. These were fundamental documents NIST relied upon to justify and gain funding. Shaffer managed the production of and/or editing of hundreds of publications including: Dimensions/NBS; Technology for Economic Growth: President's Progress Report, (November 1993); Guide to NIST, Delivering Results: A Progress Report from the NIST, (May 1995); NIST at 100: Foundations for Progress, (October 2000).
HONORS:
NBS Bronze Medal (1975)
U.S. Department of Commerce Silver Medal (1991
Influence of Isotopologue Dipole Moments on Precision Dielectric-Constant Measurements
No full textMeasurements of the relative permittivity (static dielectric constant) of fluids such as methane have been interpreted with the assumption of zero dipole moment. This assumption is not strictly true, due to the presence of isotopologues with small, nonzero dipole moments. We investigate the significance of this effect by analyzing the effect of the dipole of CH3D on the static dielectric constant of methane. It is found that the isotopologue effect is more than two orders of magnitude smaller than the uncertainty of the best existing measurements. Similar estimates for other compounds such as H-2 and CO2 produce even smaller effects. Therefore, the interpretation of these measurements with a dipole moment of zero remains valid
Scatter Corrections in X-Ray Computed Tomography: A Physics-Based Analysis
No full textFundamental limits for the calculation of scattering corrections within X-ray computed tomography (CT) are found within the independent atom approximation from an analysis of the cross sections, CT geometry, and the Nyquist sampling theorem, suggesting large reductions in computational time compared to existing methods. By modifying the scatter by less than 1 %, it is possible to treat some of the elastic scattering in the forward direction as inelastic to achieve a smoother elastic scattering distribution. We present an analysis showing that the number of samples required for the smoother distribution can be greatly reduced. We show that fixed forced detection can be used with many fewer points for inelastic scattering, but that for pure elastic scattering, a standard Monte Carlo calculation is preferred. We use smoothing for both elastic and inelastic scattering because the intrinsic angular resolution is much poorer than can be achieved for projective tomography. Representative numerical examples are given
Background and Review of Cavity-Enhanced Spontaneous Parametric Down-Conversion
No full textSpontaneous parametric down-conversion (SPDC) in a nonlinear crystal has been a workhorse for the generation of entangled and correlated single-photon pairs used for quantum communications applications for nearly three decades. However, as a naturally broadband process, the ability of SPDC to interface with the very narrow energy transitions in atomic ensembles for implementing quantum memories, which are needed for quantum repeaters to extend the reach of quantum communications, was initially limited. To overcome this limitation, the process was enhanced by placing the nonlinear crystal inside a resonating cavity. This modified process has some important advantages, including narrowing the spectral linewidth of generated photons into brighter resonant modes of the cavity, and the ability to lock the desired mode of the cavity to the targeted transition frequency of the atomic ensemble. This paper presents an overview of the principle of cavity-enhanced SPDC, a review of works to date using this technique, and an example of one of these implementations
DALE P. BENTZ
No full textDALE P. BENTZ
NBS/NIST: 1980-1987 and 1988-2018
INDUCTED: 2019
B: 1962, Waynesboro, Pennsylvania
EDUCATION:
University of Maryland, College Park, BS (Chemical Engineering), 1984
Hood College, MS (Computer and Information Science), 1991
Mount Saint Mary’s University, MA (Teaching), 2013
CITATION: For exceptional service and contributions via laboratory experiments and computer modeling leading to groundbreaking advances in the concrete materials industry.
POSITIONS HELD AT NBS/NIST:
Physical Science Aid, Fibrous Systems Division, Center for Materials Science, National Measurement Laboratory, 1980-1982
Physical Science Aid, Organic Materials Group, Center for Building Technology (CBT), National Engineering Laboratory (NEL), 1983-1984
Chemical Engineer, Organic Materials Group, CBT, NEL, 1984-1987
Chemical Engineer, Inorganic Materials Group, Building and Fire Research Laboratory (BFRL)/Engineering Laboratory, 1988-2018
HONORS:
IR-100 Award for Infrared Surface Profilometer (1987)
Maryland Distinguished Young Engineer (1998)
NIST Bronze Medal (1998 and 2009)
RILEM Robert L'Hermite Medal (1998)
American Ceramic Society Cements Division Brunauer Award (best paper) (1998)
American Concrete Institute Wason Research Medal (best paper) (2007)
Expanded Shale, Clay, and Slate Institute (ESCSI) Frank G. Erskine Award (2007)
BFRL Communicator Award (2009)
U.S. Department of Commerce Silver Medal (2009)
Magazine of Concrete Research Best Paper Award (2011)
American Concrete Institute Cedric Willson Lightweight Aggregate Concrete Award (2015)
Fellow, American Concrete Institute (2018)
MEMBERSHIPS:
American Concrete Institute
ASTM International (C01 Cements Division honorary membership, 2015)
RILEM
PUBLICATIONS:
More than 360 publications including:
Bentz, D.P. and Garboczi, E.J., "Percolation of Phases in a Three-Dimensional Cement Paste Microstructural Model", Cement and Concrete Research, Vol. 21 (2), 325-344 (1991)
Bentz, D.P., "Three-Dimensional Computer Simulation of Cement Hydration and Microstructure Development", Journal of the American Ceramic Society, Vol. 80 (1), 3-21 (1997)
Bentz, D.P., and Snyder, K.A., "Protected Paste Volume in Concrete: Extension to Internal Curing Using Saturated Lightweight Fine Aggregate", Cement and Concrete Research, Vol. 29, 1863-1867 (1999)
Bentz, D.P., "Blending Different Fineness Cements to Engineer the Properties of Cement-Based Materials", Magazine of Concrete Research, Vol. 62 (5), 327-338 (2010)
Bentz, D.P., Snyder, K.A., and Peltz, M.A., "Doubling the Service Life of Concrete Structures. II: Performance of Nanoscale Viscosity Modifiers in Mortars", Cement and Concrete Composites, Vol. 32 (3), 187-193 (2010
NIST-4 Kibble Balance Model
No full textThis model of the NIST-4 Kibble Balance is a half-scale representation of the actual instrument. The full-size Kibble Balance is 2.5 meters (~8 feet) tall when enclosed in its vacuum chamber. This model was made for the NIST Museum in Gaithersburg in celebration of the 2019 World Metrology Day. The model was designed by Frank Seifert and Leon Chao, NIST physicists who designed the full-scale balance, and the NIST Gaithersburg Fabrication Technology Office built the model. \n\n On May 20, 2019, the SI unit of mass, the kilogram, was redefined to be based on a fundamental constant, the Planck constant. The NIST-4 Kibble Balance, previously known as the Watt Balance, was one of four instruments that contributed to this effort and the precise determination of the Planck constant.\n\n Originally conceptualized in 1975 by Bryan Kibble at the United Kingdom's National Physical Laboratory, the Kibble Balance equalizes the weight of a test mass with a force produced when an electrical current is run through a coil of wire immersed in magnetic field. The balance virtually compares mechanical power to electrical power where the velocity of the coil, local acceleration of gravity, two voltages, and electrical resistance are measured precisely to calculate the value of the test mass. The voltage and resistance measurements are compared to two quantum standards, the Programmable Josephson Voltage System and the Quantum Hall Resistor, both of which are linked to the Planck constant. \n\n The cutaway section shows the samarium-cobalt (SmCo) magnetic system around the measurement coil. The colors represent the magnetic field strength, purple is low and red is high strength. Magnetic flux is represented by the black lines. It is desirable for the magnetic flux to be vertically uniform and pointing radially outward in the region where the measurement coil resides.[H] 91.44 cm __[W] 50.8 cm __[D] 45.72 c
X-ray Computed Tomography Instrument Performance Evaluation, Part II: Sensitivity to Rotation Stage Errors
No full textX-ray computed tomography (XCT), long used in medical imaging and defect inspection, is now increasingly used for dimensional measurements of geometrical features in engineering components. With widespread use of XCT instruments, there is growing need for the development of standardized test procedures to verify manufacturer specifications and provide pathways to establish metrological traceability. As technical committees within the American Society of Mechanical Engineers (ASME) and the International Organization for Standardization (ISO) are developing documentary standards that include test procedures that are sensitive to all known error sources, we report on work exploring one set of error sources, instrument geometry errors, and their effect on dimensional measurements. In particular, we studied detector and rotation stage errors in cone-beam XCT instruments and determined their influence on sphere center-to-center distance errors and sphere form errors for spheres located in the tomographically reconstructed measurement volume. We developed a novel method, called the single-point ray tracing method, that allows for efficient determination of the sphere center-to-center distance error and sphere form error in the presence of each of the different geometry errors in an XCT instrument. In Part I of this work, we (1) describe the single-point ray tracing method, (2) discuss optimal placement of spheres so that sphere center-to-center distance errors and sphere form errors are sensitive to the different detector geometry errors, and (3) present data validating our method against the more conventional radiograph-based tomographic reconstruction method. In Part II of this work, we discuss optimal placement of spheres so that sphere center-to-center distance errors and sphere form errors are sensitive to error sources associated with the rotation stage. This work is in support of ongoing standards development activity within ASME and ISO for XCT performance evaluation
Software to Report Product and Manufacturing Information in QIF Files
No full textThe QIF PMI Report (QPR) software generates a spreadsheet from a Quality Information Framework (QIF) file containing Product and Manufacturing Information (PMI). QIF is a unified XML framework standard for computer-aided quality QIF systems, available free to all implementers. QIF enables the capture, use, and re-use of metrology-related information throughout the Product Lifecycle Management
(PLM) and Product Data Management (PDM) domains. QIF was created by the Digital Metrology Standards Consortium
A Purely Algebraic Justification of the Kabsch-Umeyama Algorithm
No full textThe constrained orthogonal Procrustes problem is the least-squares problem that calls for a rotation matrix that optimally aligns two matrices of the same order. Over past decades, the algorithm of choice for solving this problem has been the Kabsch-Umeyama algorithm, which is effectively no more than the computation of the singular value decomposition of a particular matrix. Its justification, as presented separately by Kabsch and Umeyama, is not totally algebraic since it is based on solving the minimization problem via Lagrange multipliers. In order to provide a more transparent alternative, it is the main purpose of this paper to present a purely algebraic justification of the algorithm through the exclusive use of simple concepts from linear algebra. For the sake of completeness, a proof is also included of the well known and widely used fact that the orientation-preserving rigid motion problem, i.e., the least-squares problem that calls for an orientation-preserving rigid motion that optimally aligns two corresponding sets of points in d-dimensional Euclidean space, reduces to the constrained orthogonal Procrustes problem