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Search Publications by: Craig M. Shakarji (Fed)

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Displaying 1 - 25 of 54

ROLE OF MEDIAN CURVES AND SURFACES AND THEIR COMPUTATIONS IN COORDINATE METROLOGY

November 15, 2024
Author(s)
Craig Shakarji, Kexin Yin, Qunfen Qi, Edward Morse, Vijay Srinivasan
This paper explores a novel role for median curves and surfaces in coordinate metrology, and the techniques to compute these curves and surfaces. The role includes the important problem of identifying potential outliers in two- and three-dimensional

DIMENSIONAL METROLOGY IN DETERMINATION OF G WITH BIPM'S TORSION BALANCE

November 7, 2022
Author(s)
Vincent Lee, Stephan Schlamminger, Leon Chao, David B. Newell, Jon Pratt, Craig Shakarji, Clive Speake
This paper discusses the dimensional metrology challenges encountered while performing G measurements using the BIPM torsion balance and our solutions.

Performance evaluation of laser trackers using the network method

July 30, 2020
Author(s)
Ling Wang, Balasubramanian Muralikrishnan, Octavio Icasio Hernandez, Craig M. Shakarji, Daniel S. Sawyer
Due to their accuracy, portability, and large working volume, laser trackers (LTs) are widely used for dimensional metrology in a variety of large-scale manufacturing and assembly operations. Their performance evaluation is a key concern for users

Constrained Least-Squares Fitting for Tolerancing and Metrology

July 1, 2019
Author(s)
Craig M. Shakarji, Vijay Srinivasan
Recent years have seen a remarkable emergence of a particular type of least-squares fitting, called constrained least-squares fitting, in national and international standards on tolerancing and metrology. Fitting, which is called an association operation

The 2016 revision of ISO 1 – Standard reference temperature for the specification of geometrical and dimensional properties

November 10, 2016
Author(s)
Steven D. Phillips, Craig M. Shakarji, Alessandro Balsamo, Michael Krystek, Edward P. Morse
This paper discusses the recently published 2016 (third edition) of ISO 1. While the value of the standard reference temperature remains unchanged at 20 C, definitions for the reference temperature and standard reference temperature are now included. This

Datum Planes Based on a Constrained L1 Norm

December 1, 2015
Author(s)
Craig M. Shakarji, Vijay Srinivasan
This paper has two major goals. First, we present an algorithm for establishing planar datums suitable for a default in tolerancing standards. The algorithm is based on a constrained minimization search based on the L_1 (L1) norm after forming a convex

A Constrained L2 Based Algorithm for Standardized Planar Datum Establishment

November 18, 2015
Author(s)
Craig M. Shakarji, Vijay Srinivasan
For years (decades, in fact) a definition for datum planes has been sought by ASME and ISO standards writers that combines the contacting nature of traditional surface plate mating with a means of balancing rocking conditions when there is a centrally

Evaluation of the Range Performance of Laser Scanners Using Non-planar Targets.

November 1, 2015
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Craig M. Shakarji, Vincent D. Lee, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is supporting the development of documentary standards for performance evaluation of Laser scanners. This evaluation could be performed by determining the

Design and calibration of an artifact for evaluating laser scanning articulating arm CMMs used for measuring complex non-concurrent surfaces

October 30, 2015
Author(s)
Vincent D. Lee, Steven D. Phillips, Craig M. Shakarji, Jeffrey Hosto, Jeffrey Huber, Gillich Barbara
Dimensional metrology is a foundational science finding applications throughout modern technology, including the testing of human-worn body armor designed to mitigate damage from kinetic projectiles fired from small arms. We describe the design and

Considerations for Design and In-Situ Calibration of High Accuracy Length Artifacts for Field Testing of Laser Trackers

March 1, 2015
Author(s)
Aaron Hudlemeyer, Daniel S. Sawyer, Christopher J. Blackburn, Vincent Lee, Mark Meuret, Craig M. Shakarji
Interim testing of laser trackers can be problematic due to the lack of high precision, long length artifacts that maintain their calibrated lengths during measurement. Gravitational loading, fixturing forces, and changes in the atmospheric conditions can

In-situ Temperature Calibration Capability for Dimensional Metrology

December 15, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has developed a new in-situ temperature calibration system. This paper discusses the system components, an in-situ calibration procedure, the uncertainty

In-situ Temperature Calibration Capability for Dimensional Metrology

December 1, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has the capability to perform large range dimensional measurements in a facility, called the Tape Tunnel. The Tape Tunnel is equipped with a 60 m long steel

Evaluating CT for Metrology: The Influence of Material Thickness on Measurements

October 7, 2014
Author(s)
Joseph Schlecht, Eric Ferley, Shaun COUGHLIN , Steven D. Phillips, Vincent Lee, Craig M. Shakarji
X-ray imaging provides a non-destructive means to measure internal features of a workpiece, and CT offers unique capabilities for internal measurements in 3-D. However, due to the computational nature of CT and its indirect measurement process, assessing