CONTENTdm Title

Comparison theorems for symmetric functions of characteristic roots
Characteristic roots; comparison theorems; symmetric functions
Several theorems are proved that give necessary and sufficient conditions for A-B to be positive semidefinite Hermitian. The conditions are in terms of the comparison of elementar y symmetric functions of the charactelistlc roots of A+X and B+X as...
Journal of Research of NIST and Predecessor Publications

X-ray measurement of residual strains in individual grains of polycrystalline aluminum
Shifts in peak position of {333} and {511} diffractions of cobalt Ka1 x rays from individual grains of coarse-grained polycrystalline aluminum observed in the annealed condition and after 10 percent plastic extension revealed residual strains in...
Journal of Research of NIST and Predecessor Publications

Tensile deformation of vapor-deposited copper reinforced with tungsten wires
Composites; copper; electrical conductivity; fracture; law of mixtures; metallic bonding; tensile properties; tungsten; vapor-deposition; wires
Short-time tensile tests were made at room temperature on sheet specimens of vapor-deposited copper containing zero to 26 volume percent continuous tungsten wires having diameters of 0.0005, 0.001, and 0.005-inch. Specimens were annealed at 25,...
Journal of Research of NIST and Predecessor Publications

Rosa Curve Tracer
Shortly before coming to the National Bureau of Standards in 1901, Dr. Edward B. Rosa had invented a curve tracer while teaching at Wesleyan University in Middleton, Connecticut. The curve tracer visually mapped alternating current curves, which...
NIST Museum Artifacts

Groundbreaking Shovel Gaithersburg Campus
Shovel used on June 14, 1961 for the groundbreaking ceremony of the National Bureau of Standards Gaithersburg, Maryland campus.
NIST Museum Artifacts

Dr. L. S. Taylor, chief of the x-ray section at NBS, making adjustments to equipment before a test in the target room of the x-ray laboratory
Photographs; History; Metrology; X-ray; Standardization; History; Laboratories; Instruments
Shown is the target room of the x-ray laboratory, where x-rays were bent at an angle of 90 degrees, directly into the ionization chamber (right half of the picture), which provided the basic measurement information. All of the equipment was turned...
Historic Images

Judges for the junior high school exhibits at the First Annual Regional Science Fair held at the NBS Boulder Laboratories on April 28, 1956
Photographs; History; Metrology; Science projects; Awards; 1950s
Shown judging the junior high school exhibits at the First Annual Regional Science Fair held at the NBS Boulder Laboratories on April 28, 1956 are A.S. Anderson, Colorado Engineering Council; Fred W. Brown, NBS; Robert T. Porter, Colorado State...
NBS-NIST Campuses, Buildings, and Labs

Camera station on test field at Warren Grove, NJ
Photographs; History; Metrology; Guided missiles; Proximity fuzes; Ordnance; World War, 1939-1945
Shown: two Eastman aerial cameras, type K-24, mounted to permit tracking of the gliding BAT missile. Two-way radio communication kept the operator informed of activities and in the air.
Historic Images

Radio compass with amplifier in actual operation
Photographs; History; Metrology
Signals are received on this small cord from ships at sea. The images in this collection can be found in the NIST special publication ""NIST at 100: Foundations for Progress,"" published in October 2000 and available at...
NBS-NIST History and Events

Relation of vitron theory to 2-layer-liquid immiscibility in binary silicate and borate glass melts
Binary borates; binary silicates; boron glass; glass; homogenization of glass melts; immiscible glass melts; immiscibility gaps; silica glass; structure of glass; vitron theory
Silica-rich and boron-rich binary glasses resemble clathrates in having host cavities in which modifier oxides may be inclosed without stress as inactive guests until the cavities are approximately filled. Additional modification results in stress...
Journal of Research of NIST and Predecessor Publications

Potential Stable Low-Permeation Rate Standard Based on Micro-machined Silicon
calibration; chilled mirror hygrometer; mass loss; permeation; Si; standard
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...
Journal of Research of NIST and Predecessor Publications

Double Meter Length Standard
Silver colored metal length standard, heavily rusted at one end. The artifact is marked with a 1C sticker.
NIST Museum Artifacts

Photolytic behavior of silver iodide
Silver iodide exposed to high intensity radiation in the visible light spectrum was found to yield a powder X-ray diffraction pattern showing marked deviations from ideality. It was found possible to correlate these with a decrease in primary...
Journal of Research of NIST and Predecessor Publications

Length Standard No. 42
Silver-colored meter length standard No. 42. The artifact is marked with a 2C sticker.
NIST Museum Artifacts

Acid-assisted consolidation of silver alloys for direct fillings
acid-assisted consolidation; cold-welding; consolidated silver
Silver-rich metal powders cold-welded by consolidation have been investigated as possible direct dental filling material. The surface of the silver powder must undergo an acid treatment to remove existing contaminants and prevent formation of new...
Journal of Research of NIST and Predecessor Publications

Bounds for the solutions of second-order linear difference equations
Chebyshev series; difference equations; error bounds; Miller algorithm; recurrence relations; special functions
Simple bounds are established for the solutions of second-order homogeneous linear difference equations in ranges in which the solutions are exponential in character. The results are applied to a recent algorithm for the computation of subdominant...
Journal of Research of NIST and Predecessor Publications

Exact solution to an interacting extreme-value problem: The pure-flaw model
extreme-value distributions; scaling analysis; size effect in fracture
Simple models play a key role in the microstructural analysis of mechanical failure in composites and other materials with complex and often disordered microstructures. Although equal load-sharing-models are amenable to rigorous statistical...
Journal of Research of NIST and Predecessor Publications

Two classical theorems on commuting matrices
Commuting matrices; group representations; normal matrices; Schur's lemma; simultaneous triangularization and diagonalization
Simple proofs are given of the following classical theorems: (1) An arbitrary set of commuting matrices may be simultaneously brought to triangular form by a unitary similarity. (2) An arbitrary set of commuting normal matrices may be...
Journal of Research of NIST and Predecessor Publications

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