The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.
Early in 2022 NIST embarked on a pilot project to produce digital calibration reports and certificates of analysis for reference materials. The goal of the project was to produce a few examples of each for the purpose of assessing the scope and challenges of digital transformation for these measurement services. This presentation is focused on the digital calibration reports. Our aims for this portion of the pilot project are to generate a digital calibration report from calibration data, customer metadata, and other data and metadata as needed; to generate a human readable report from the digital calibration report; and to hold a workshop to gather stakeholder feedback. The digital calibration certificate (DCC), which developed as an outgrowth of the SmartCom 17IND02 project, is used as a starting point. However, challenges for NIST include the wealth of information presently contained in NIST reports, reports with complex data, and the secure nature of NIST calibration reports (NIST calibration reports, data, and metadata are not public). Other practical challenges include the wide variety of calibration services offered by NIST, as well as the needs of internal and external stakeholders. This publication reports on the progress of the NIST effort and discusses some of the challenges and potential solutions to producing digital calibration reports.
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