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Oral history interview of Ruth M. Davis, May 6, 2003/ with Lisa Greenhouse.
No full text(Transcript) Oral history interview of Ruth M. Davis, May 6, 2003/ with Lisa Greenhouse
Repeatability and reproducibility standard deviations in the measurement of trace moisture generated using permeation tubes
No full textPermeation-tube moisture generators are used in industry as calibrated sources of water vapor and carrier gas mixtures. Measurements were made using three permeation-tube moisture generators of the type used in the semiconductor industry. This paper describes repeatability and reproducibility standard deviations in measurement of moisture concentration from such generators. Repeatability refers to measurements within a system and reproducibility refers to measurements between systems. Two independent methods were used to measure the realized concentration of water vapor. The first measurement, the calculated value, was determined using calibrated permeation rate of permeation-tube and flow rate of dry carrier gas. This is the industrial method of evaluating moisture concentration. The second measurement, the measured value, was determined using the low frost-point generator at the National Institute of Standards and Technology (NIST) and a quartz-crystal-micro-balance. Four pairs of independent measurements for each generator and for six nominal levels in the range from 10 nL/ L to 100 nL/ L were made. The characteristic used to quantify repeatability and reproducibility standard deviations in industrial measurements is the calculated value minus the measured value. Repeatability standard deviation ranges from 1 nL/ L to 2 nL/ L, approximately. Reproducibility standard deviation ranges from 2 nL/ L to 8 nL/ L, approximately. The documentary ASTM standard E691-99 was used for both data validation and quantification of the repeatability and reproducibility standard deviations
(Audio Part 3 of 3) Oral history interview of John Hoffman, May 8, 2003
No full textDr. John Hoffman discusses his long career at NIST. His career spanned the years 1954 to 1982, during which time he was in various leadership positions, including Director of the Institute for Materials Research and Director of the National Measurement laboratory
(Audio Part 3 of 4) Oral history interview of John Hoffman, May 23, 2003
No full textDr. John Hoffman discusses his long career at NIST. His career spanned the years 1954 to 1982, during which time he was in various leadership positions, including Director of the Institute for Materials Research and Director of the National Measurement laboratory
(Transcript) Oral history interview of Bourdon F. Scribner, February 24, 2003 / by Lisa Greenhouse, Bill Martin, and David Lide
No full textBourdon Scribner, former Chief of the Spectrochemistry division, discusses his career at NBS, including working with Dr. William Meggers, his testimony before Congress on the AD-X2 battery additive, and his visits to the Bureau when his father, Bourdon W
Evaluation of intrusion detection systems
No full textThis paper presents a comprehensive method for evaluating intrusion detection systems (IDSs). It integrates and extends ROC (receiver operating characteristic) and cost analysis methods to provide an expected cost metric. Results are given for determining the optimal operation of an IDS based on this expected cost metric. Results are given for the operation of a single IDS and for a combination of two IDSs. The method is illustrated for: 1) determining the best operating point for a single and double IDS based on the costs of mistakes and the hostility of the operating environment as represented in the prior probability of intrusion and 2) evaluating single and double IDSs on the basis of expected cost. A method is also described for representing a compound IDS as an equivalent single IDS. Results are presented from the point of view of a system administrator, but they apply equally to designers of IDSs
Simulation of an Austenite-twinned-Martensite interface
No full textDeveloping numerical methods for predicting microstructure in materials is a large and important research area. Two examples of material microstructures are Austenite and Martensite. Austenite is a microscopic phase with simple crystallographic structure while Martensite is one with a more complex structure. One important task in materials science is the development of numerical procedures which accurately predict microstructures in Martensite. In this paper we present a method for simulating material microstructure close to an Austenite-Martensite interface. The method combines a quasi-Newton optimization algorithm and a non-conforming finite element scheme that successfully minimizes an approximation to the total stored energy near the interface of interest. Preliminary results suggest that the minimizers of this energy functional located by the developed numerical algorithm appear to display the desired characteristics
High accuracy ultraviolet index of refraction measurements using a Fourier transform spectrometer
No full textWe have constructed a new facility at the National Institute of Standards and Technology (NIST) to measure the index of refraction of transmissive materials in the wavelength range from the visible to the vacuum ultraviolet. An etalon of the material is illuminated with synchrotron radiation, and the interference fringes in the transmittance spectrum are measured using a Fourier transform spectrometer. The refractive index of calcium fluoride, CaF2, has been measured from 600 nm to 175 nm and the resulting values agree with a traditional goniometric measurement to within 1 x 10(-5). The uncertainty in the index values is currently limited by the uncertainty in the thickness measurement of the etalon
Accuracy of nanoscale pitch standards fabricated by laser-focused atomic deposition
No full textThe pitch accuracy of a grating formed by laser-focused atomic deposition is evaluated from the point of view of fabricating nanoscale pitch standard artifacts. The average pitch obtained by the process, nominally half the laser wavelength, is simply traceable with small uncertainty to an atomic frequency and hence can be known with very high accuracy. An error budget is presented for a Cr on sapphire sample, showing that a combined standard uncertainty of 0.0049 nm, or a relative uncertainty of 2.3 x 10(-5), is readily obtained, provided the substrate temperature does not change. Precision measurements of the diffraction of the 351.1 nm argon ion laser line from such an artifact are also presented. These yield an average pitch of (212.7777 +/- 0.0069) nm, which agrees well with the expected value, as corrected for thermal contraction, of (212.7705 +/- 0.0049) nm