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A review of calorimeters and experimental procedures used for measurement of enthalpies of vaporization for pure liquids is presented. The calorimetric approaches that are illustrated give an insight into direct determination of enthalpies of vaporization
All current watt balances employ permanent magnet systems using a yoke with high permeability as flux return. Very often these systems are built with vertical and azimuthal symmetries. In its simplest form, the air gap is defined by an inner and outer yoke
Eleanor M. Waxman, Kevin C. Cossel, Gar Wing Truong, Fabrizio R. Giorgetta, William C. Swann, Sean Coburn, Robert J. Wright, Gregory B. Rieker, Ian R. Coddington, Nathan R. Newbury
Keith A. Gillis, XiaoJuan Feng, Jintao Zhang, H. Lin, James B. Mehl, Michael R. Moldover, K Zhang, Y.N. Duan
We report a new determination of the Boltzmann constant k B using a cylindrical acoustic gas thermometer. We determined the length of the copper cavity from measurements of its microwave resonance frequencies. This contrasts with our previous work (Zhang
Igor Vayshenker, Robert D. Horansky, John H. Lehman, Malcolm G. White, Sae Woo Nam, Ingmar Mueller, Lutz Werner, G. Wuebbeler
In the recent years several ways to radiometrically calibrate optical fiber-coupled detectors have been developed. However, fiber-coupled calibration methods for single photon detectors have not been compared by national metrology institutes validating the
Georgia L. Harris, Flora Mercader, Adriana Veraza, Salvador Echeverria Villagomez
2016 was an exciting year for international collaboration on metrology education and training. This paper provides a 3-part look at how a Fulbright Specialist grant supported collaboration between the United States and Mexico. Part 1 describes the
Wei Ren, Theodore D. Doiron, John R. Stoup, Eric S. Stanfield
High-accuracy Coordinate Measuring Machine (CMM) is always a good option to measure the dimensions on a variety of artifacts. However, due to the large length-to-width ratio of the cuvettes, a CMM is unable to measure the gaps of cuvettes. Therefore, a non
Richard J. Sheridan, Sara V. Orski, Ronald L. Jones, Sushil K. Satija, Kathryn L. Beers
We present a method for the direct measurement of the relative energy of interaction between a solvated polymer and a solid interface. By tethering linear chains covalently to the surface, we ensured the idealized and constant configuration of polymer
Ho Yeung, Brandon Lane, Jason Fox, Felix Kim, Jarred C. Heigel, Jorge Neira
Research has shown significant influence of laser scan strategy on various part qualities in the laser powder bed fusion additive manufacturing process. The National Institute of Standards and Technology developed the Additive Manufacturing Metrology
This paper addresses the combinatorial characterizations of the optimality conditions for constrained least-squares fitting of circles, cylinders, and spheres to a set of input points. It is shown that the necessary condition for optimization requires
Erich N. Grossman, Richard A. Chamberlin, David R. Novotny, Joshua A. Gordon, Nina P. Basta
We describe bistatic scattering measurements on eight reference targets constructed from Al 2O 3 grit of various sizes embedded in an absorptive epoxy matrix. These samples' surface topographies were measured using focus-variation microscopy, and their
Ann C. Chiaramonti Debay, Jay D. Goguen, Edward J. Garboczi
We now know that, in addition to the size distribution, the specific shapes and orientations of regolith particles play a major role in determining the light scattering properties of lunar soil and other planetary regoliths. Our goal is to model light
Dale E. Newbury, Nicholas W. Ritchie, Michael J. Mengason, Keana C. Scott
Elemental trace analysis by electron-excited x-ray spectrometry performed in the scanning electron microscope (SEM) with energy dispersive x-ray spectrometry (EDS) can reach a limit of detection of 0.0005 mass fraction for many elements. Exceptions include
Eric C. Benck, Corey A. Stambaugh, Edward C. Mulhern, Patrick J. Abbott, Zeina J. Kubarych
The kilogram is the unit of mass in the International System of units (SI) and has been defined as the mass of the International Prototype Kilogram (IPK) since 1889. In the future, a new definition of the kilogram will be based on precise measurements of
Stacey M. Louie, Justin Gorham, Jiaojie Tan, Vincent A. Hackley
Polymeric coatings are commonly applied to impart functionality and colloidal stability to engineered nanoparticles. In natural environments, transformations of the coating can modify the particle transport behavior, but the mechanisms and outcomes of
Brian J. Simonds, Jeffrey W. Sowards, Paul A. Williams
Optical spectral analysis of the laser weld plume is common practice as it is a non-contact, in situ technique. However, the low sensitivity of optical emission spectroscopy limits the available information during 1070 nm wavelength laser welding, which is
High precision mass comparisons are typically performed such that both masses are measured under nearly identical conditions. However, there are situations where an artefact needs to be calibrated against a standard kept under different conditions. For
In general, the dynamic sensitivity of a force transducer depends upon the mechanical system in which it is used. This dependence serves as motivation to develop a dynamic force transfer standard, which can be used to calibrate a working transducer "in
Felix Kim, Edward Garboczi, Shawn P. Moylan, John Slotwinski
Pore structures of additively manufactured metal parts were investigated with X-ray Computed Tomography (XCT). Disks made of a cobalt-chrome alloy were produced using laser-based powder bed fusion (PBF) processes. The additive manufacturing processing
Jon C. Geist, Muhammad Y. Afridi, Craig McGray, Michael Gaitan
Cross-sensitivity matrices are used to translate the response of three-axis accelerometers into components of acceleration along the axes of a specified coordinate system. For inertial three-axis accelerometers, this coordinate system is often defined by
Vyacheslav B. Podobedov, George P. Eppeldauer, Thomas C. Larason
A new night vision goggles (NVG) gain definition for the calibration process is proposed and evaluated. This definition is based on the radiance measurements at the input and output of the NVG. In contrast to the old definition which uses a non-
Matthias J. Merzkirch, Louise A. Ahure Powell, Timothy J. Foecke
Numerical models based on cohesive zones are usually used to model and simulate the mechanical behavior of laminated carbon fiber reinforced polymers (CFRP) in automotive and aerospace applications. The codes of these models require different interlaminar
Critical dimension atomic force microscopy (CD-AFM) is a measurement technique that uses flared tips and two-dimensional surface sensing to enable scanning of features with near-vertical sidewalls. A major source of uncertainty in metrology with CD-AFM is