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National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures , we have(More)
A simplified realization for the Gaussian filter in surface metrology is presented in this paper. The sampling function u u sin is used for simplifying the Gaussian function. According to the central limit theorem, when n approaches infinity, the function () n u u sin approaches the form of a Gaussian function. So designed, the Gaussian filter is easily(More)
Parameters of surface roughness and step height are currently measured at the National Institute of Standards and Technology (NIST) by means of a computerized/stylus instrument. For roughness height parameters, we use a calibration ball as a master to calibrate the instrument to be employed during a measurement. Profiles of the calibrating master and the(More)
In response to the guidelines issued by the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLD/LAB-International) to establish traceability and quality assurance in U.S. crime laboratories, NIST and the ATF initiated a joint project, entitled the National Ballistics Imaging Comparison (NBIC). The NBIC project aims to(More)
Some automated bullet identification systems calculate a correlation score between two land impressions to measure their similarity. When extracting a compressed profile from the land impression of a fired bullet, inclusion of areas that do not contain valid individual striation information may lead to sub-optimal extraction and therefore may deteriorate(More)
The program responds to the mandate of the Justice System Improvement Act of 1979, which directed NIJ to encourage research and development to improve the criminal justice system and to disseminate the results to Federal, State, and local agencies. The Law Enforcement and Corrections Standards and Testing Program is an applied research effort that(More)
The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several(More)
The decreasing size of semiconductor features and the increasing structural complexity of advanced devices have placed continuously greater demands on manufacturing metrology, arising both from the measurement challenges of smaller feature sizes and the growing requirement to characterize structures in more than just a single critical dimension. For(More)