ABSTRACT
This paper discusses the changes in the 2016 (third edition) of International Standard ISO 1. While the value of the standard reference temperature remains unchanged at 20 °C, the important definitions for the "reference temperature" and "standard reference temperature," absent in prior editions, are now defined, with the latter exclusively reserved for the assignment of the internationally agreed upon temperature of 20 °C. The scope of the revised Standard has been carefully refined and made more explicit. This, together with other clarifications and improvements, has eliminated the ambiguities associated with specifications at non-standard reference temperatures and allows, if needed, different reference temperatures to be associated with different properties of a workpiece. The relationship between ISO 1 and dimensional measurements is also discussed and clarified. In this paper, we discuss the motivation for these changes and present several issues debated during the revision process for the benefit of future standards committees that might study this topic.
ABSTRACT
This paper describes a threefold method of testing the performance of an array-based ultrasonic tool for nondestructive testing of spot welds. The tool is described in its capabilities, use, and advantages over existing counterparts. Performance testing for and the results from carrying out the testing are described. The three performance testing methods include 1) the use of calibrated samples, 2) comparisons with actual spot-welds, and 3) a performance evaluation of the embedded fitting software. The test of the fitting software was carried out by a comparison of results with reference fits supplied by the National Institute of Standards and Technology.
ABSTRACT
Our high technology society continues to rely more and more upon sophisticated measurements, technical standards, and associated testing activities. This was true for the industrial society of the 20th century and remains true for the information society of the 21st century. Over the last half of the 20th century, information technology (IT) has been a powerful agent of change in almost every sector of the economy. The complexity and rapidly changing nature of IT have presented unique technical challenges to the National Institute of Standards and Technology (NIST) and to the scientific measurement community in developing a sound measurement and testing infrastructure for IT. This measurement and testing infrastructure for the important non-physical and non-chemical properties associated with complex IT systems is still in an early stage of development. This paper explains key terms and concepts of IT metrology, briefly reviews the history of the National Bureau of Standards/National Institute of Standards and Technology (NBS/NIST) in the field of IT, and reviews NIST's current capabilities and work in measurement and testing for IT. It concludes with a look at what is likely to occur in the field of IT over the next ten years and what metrology roles NIST is likely to play.
