Reevaluating the NIST Uncertainties for AC-DC Voltage Transfer Difference

Accurate calibration of ac voltages up to 1000 V by using thermal converters requires range resistors connected in series with the converter. The combination of a thermal converter and range resistor is known as the thermal voltage converter. In this paper, multi-range internal range resistors are designed and implemented in the National Institute for Standards (NIS), Egypt to cover the ac voltage ranges from 10 V to 750 V. The range resistor values are 2 kΩ, 10 kΩ, 20 kΩ, 40 kΩ, 100 kΩ, and 150 kΩ to cover the voltage ranges 10 V, 50 V, 100 V, 200 V, 500 V, and 750 V, respectively. The six range resistors are mounted in series with a single-junction thermo-element in the same box to provide a new thermal voltage converter. The required range resistor is selected by using a six-pin selector switch. Each resistor is connected to a selector pin. The new thermal voltage converter ranges are automatically calibrated against other standard thermal voltage converters at different frequencies by using a LabVIEW program to determine their ac–dc transfer difference at each range. The expanded uncertainties are estimated according to the GUM for all ranges at different frequencies. The performance of the new thermal voltage converter is also evaluated by comparing its ac–dc differences and its accuracy in measuring the ac voltage at different frequencies with a traditional thermal voltage converter.

The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005, requires that calibration of mercury continuous emissions monitors (CEMs) be performed with NIST-traceable standards. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The traceability protocol will be written by EPA. Traceability will be based on the actual analysis of the output of each calibration unit at several concentration levels ranging from about 2-40 ug/m{sup 3}, and this analysis will be directly traceable to analyses by NIST using isotope dilution inductively coupled plasma/mass spectrometry (ID ICP/MS) through a chain of analyses linking the calibration unit in the power plant to the NIST ID ICP/MS. Prior to this project, NIST did not provide a recommended mercury vapor pressure equation or list mercury vapor pressure in its vapor pressure database. The NIST Physical and Chemical Properties Division in Boulder, Colorado was subcontracted under this project to study the issue in detail and to recommend a mercury vapormore » pressure equation that the vendors of mercury vapor pressure calibration units can use to calculate the elemental mercury vapor concentration in an equilibrium chamber at a particular temperature. As part of this study, a preliminary evaluation of calibration units from five vendors was made. The work was performed by NIST in Gaithersburg, MD and Joe Rovani from WRI who traveled to NIST as a Visiting Scientist.« less

The design and features of an experimental thermal ac-dc converter with frequency output are presented. A bulk acoustic wave LC-cut quartz resonator with linear frequency versus temperature characteristic is used as a temperature sensor. The resonator is excited through an inductively-coupled Butler oscillator. The sensitivity of this device is about 1 kHz/spl middot/K/sup -1/. In order to reduce the electromechanical coupling between the heater and the vibrating area, a thin-film Ni-Cr heater was sputtered at a location where the convex surface of the resonator intersects the nodal plane of the vibrations. The overall temperature coefficient of the output frequency is about -0.3%/spl times/K/sup -1/. The responsivity of the device is 300 kHz/spl times/W/sup -1/. The short-term stability of the output frequency permits an ac-dc transfer at the 10/sup -6/ level. The ac-dc voltage transfer difference of the converter is less than 10/spl times/10/sup -6/ at an input voltage of 3 V in the frequency range from (1-5) kHz. Below 1 kHz, the ac-dc transfer difference increases proportionally to the input power and doubles with a decade decrease of the input frequency. No resonances of the quartz plate were detected between 5 kHz and the frequency of the strongest fundamental thickness shear mode (9.5 MHz). Hence the converter can be probably used up to 1 MHz.

A Look at its Past Decade and a Gaze towards its Future. As the National Metrology Institute (NMI) for the United States, the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards, has provided measurement services, both calibrations and reference materials, for more than 100 years. Through these services, our customers have benefitted from our measurement capabilities and expertise in many areas, including amount of substance; dimensional metrology; electricity and magnetism; ionizing radiation; mass and related quantities; photometry and radiometry; thermodynamics; and time and frequency. NIST’s customers have also had access to some of the lowest measurement uncertainties available and a dependable way to establish traceability to the International System of Units (SI) [http://www.nist.gov/pml/wmd/metric/si-units.cfm].In response to the signing of the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA), NIST first established an institution-wide quality system for the measurement services 10 years ago [http://www.bipm.org/en/cipm-mra/objectives.html]. NIST’s Quality System for Measurement Services has advanced the quality of service and measurements we provide our customers by fostering an environment in which NIST management and staff work towards continual improvement in the development and delivery of NIST measurement services. This paper describes NIST’s Quality System for the Measurement Services and its relevance to international standards of quality, such as the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC) 17025 standard and ISO Guide 34 [http://www.nist.gov/nistqs/]. It also provides a history of this quality system and a glimpse of future goals for improving its implementation.

In the fall of 2019, the National Institute of Standards and Technology (NIST) funded threes studies to better understand equity and inclusivity. This report documents phase two of a three phased sequential, exploratory mixed methods study designed to provide an in-depth look at the population of NIST federal employees to identify factors, attitudes, and processes that might result in gender- specific barriers at NIST. Phase 1 analyzed human resources demographic data, compensation data, and performance data of NIST federal employees from 2011 to 2019 to determine any relevant trends. Phase 1 informed the development of an in-depth interview protocol designed to identify the differences, if any, in the ways in which men and women experience work at NIST. A total of 40 (36 female and 4 male) participants were interviewed. Three interconnected themes emerged in the data: 1) a culture at NIST that creates a Chilly Climate for women; 2) gendered experiences that contribute to and are outcomes of that chilly climate; and 3) gendered outcomes that influence women s experiences in the organization. The culture has evolved from NIST s scientific roots, scientific excellence, a strong belief in meritocracy, and as a Federal agency. Each of these characteristics contribute to a gendered social structure and the perception that change is not needed. This backdrop sets the stage for the characterizations of NIST from the interviews as a Boys Club and an Elitist environment. The radically different perspectives of men and women based in the culture result in experiences and outcomes that provide advantages and opportunities for men while erecting barriers to survival for women, including isolation and possibly exclusion. These barriers result in consequences of discrimination as well as lack of trust and resignation. Participant quotes are used as exemplars to provide details related to each of these themes. Overall, the interviews demonstrate that women and men experience a very different NIST.

The National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards, was established by the U.S. Congress in 1901 and charged with establishing a measurement foundation to facilitate U.S. and international commerce. NIST provides reference materials and reference instruments that are used to ensure the accuracy, metrological traceability, and comparability of measurement results in many diverse fields of science, industry, and technology. This document provides and explains the vocabulary used at NIST to describe the reference materials and reference instruments available to NIST s customers. This document also describes the methods used in developing NIST reference materials. The definitions and descriptions provided supersede those used in the original versions of this publication, NIST SP260-136 and SP260-136-2020.

This paper presents a summary of the strategies and activities underway at the National Institute of Standards and Technology (NIST) in electronics packaging, interconnection and assembly (P/I/A). In addition, a sampling of collaborations involving these works is included. The overall NIST effort in P/I/A is composed of targeted programs conducted by the NIST laboratories and by the NIST Advanced Technology Program (ATP). A dominant aspect of the laboratory-based P/I/A program focuses on the metrology and data needed to support the product technologies envisioned within industry roadmaps. A significant aspect of the work includes efforts in metrology, materials, complex material assemblies, and microelectronic components and circuits. In parallel, the NIST ATP is supporting on a cost-share basis a variety of industry-based development projects of high-risk enabling technologies for new or improved products, manufacturing, and processes in P/I/A.

Standards provide critical benefits across a wide variety of contexts, including safety and health, environmental protection, and quality of products and services. However, while these benefits are generally acknowledged, estimating the social and economic value of standards and determining how specific entities and activities influence their development require careful analysis. In October of 2018, the National Institute of Standards and Technology (NIST) asked the RAND Corporation to estimate the benefit of NIST’s research contributing to particular fire safety standards. The original objectives of the project were to (1) document the role of the NIST in the standards development process, (2) estimate the value these standards provide to society, and (3) thereby inform the economic value of NIST’s contribution to these standards. This report presents results for the first two objectives. Given that NIST’s contribution is one of several inputs combining to create these standards, NIST’s share of the credit for their value could not be quantified. Our analysis focused on case studies in standards for home smoke alarms and for protecting structures at the wildland-urban interface (WUI). Our analysis draws on a wide variety of qualitative and quantitative methods to holistically describe the impacts of these standards and NIST’s role in their development. The intended audience of this report includes those who work on fire safety research, fire safety standards, building codes, and technology transfer. The conclusions presented here may also be of interest for broader resource allocation and federal budget justification purposes. Finally, this report was written to be accessible to any interested members of the general public.

This paper gives an overview of the development of thin-film multijunction thermal converters (FMJTC's) at the National Institute of Standards and Technology (NIST). A historical perspective of film thermal converters is presented, followed by descriptions of the motivation, fabrication processes, physical characteristics, and the electrical properties of the FMJTC's produced at NIST. Integrated micropotentiometers that incorporate FMJTC's and thermal converters, produced by an alternative fabrication technology using a CMOS foundry, are also described. The paper concludes with a report on the present status of the FMJTC project and future directions.

The National Institute of Standards and Technology (NIST) timescale produces a real-time realization of UTC(NIST) in the form of a pulse-per-second (PPS) time signal and a 5 MHz frequency reference. UTC(NIST) contributes to UTC (Coordinate Universal Time) using TWSTFT (Two-Way Satellite Time and Frequency Transfer) and common-view GPS (Global Positioning System) techniques. The NIST timing signal is also disseminated to the international and domestic communities using various other techniques: NIST Automated Computer Time Service (ACTS), Internet Time Service (ITS) and NIST Time Measurement and Analysis Service (TMAS). The accuracy of NIST contribution to UTC and of the dissemination of the NIST PPS time signal depends upon the quality of the calibration of the time delay between each user and the UTC(NIST) reference point. Hardware constraints, spatial constraints, and in some cases simple convenience, require that the physical input to the transfer and dissemination equipment be distributed throughout the NIST campus. A robust on-campus timing distribution and calibration system is required to ensure the accuracy and stability of these signals: for example, the current error budget for a typical time transfer calibration requires local delays to be known to an uncertainty of less than 200 ps. We utilize a clock trip calibration protocol to measure the delays introduced by the local time distribution system at NIST: a clock trip involves measuring the time difference between the UTC(NIST) reference point and a travelling clock, then transporting the travelling clock to a secondary reference point where another measurement of the time difference is performed. Clock trips are advantageous as they are a nonintrusive measurement of the full system delay. To achieve calibrations with an accuracy on the order 100 ps, we have developed a means to transport a cesium clock between remote locations on site with minimal vibration and an analysis protocol to maximize the information acquired by each clock trip. We will introduce the system used to distribute time signals at NIST, the hardware and protocol we have developed to calibrate secondary timing reference points, and data we have collected based on their implementation.

The National Institute of Standards and Technology (NIST) has redefined its gas pressure scale, up to 17 MPa, based on two primary standard piston gauges. The primary standard piston gauges are 35.8 mm in diameter and operate from 20 kPa to 1 MPa. Ten secondary standard piston gauges, two each of five series of the Ruska 2465 type, with successively smaller diameters form the scale extending up to 17 MPa. Six of the piston gauges were directly compared to the primary standards to determine their effective area and expanded (k = 2) uncertainty. Two piston gauges operating to 7 MPa were compared to the 1.4 MPa gauges, and two piston gauges operating to 17 MPa were compared to the 7 MPa gauges. Distortion in the 7 MPa piston gauges was determined by comparing those gauges to a DH Instruments PG7601 type piston gauge, whose distortion was calculated using elasticity theory. The relative standard uncertainties achieved by the primary standards range from 3.0 × 10−6 to 3.2 × 10−6. The relative standard uncertainty of the secondary standards is as low as 4.2 × 10−6 at 300 kPa. The effective areas and uncertainties were validated by comparison to standards of other National Metrology Institutes (NMIs). Results show agreement in all cases to better than the expanded (k = 2) uncertainty of the difference between NIST and the other NMIs, and in most cases to better than the standard (k = 1) uncertainty of the difference.

On September 5–8, 2023, the National Institute of Standards and Technology (NIST) held the second Standards and Performance Metrics for On‐Road Automated Vehicles Workshop. This four‐day virtual event provided updates on NIST’s recent work in automated vehicles (AVs) and gave stakeholders an opportunity to provide feedback and input on current and future NIST research. The workshop included high‐level keynote presentations, a series of industry keynote presentations, and NIST presentations on its current AV activities. The industry keynotes and NIST presentations were paired with breakout sessions that discussed NIST’s progress, community challenges, and stakeholder research needs in six key areas: systems interaction, perception, cybersecurity, communications, artificial intelligence, and digital infrastructure. There was general agreement that developing standards allows for better comparisons and evaluations of emerging technologies. Other key themes included: 1) Digital technologies for automation and related security/privacy concerns, including artificial intelligence, machine learning, and smart communication technologies (i.e., vehicle‐to‐vehicle (V2V), vehicle‐to‐infrastructure (V2I), and vehicle‐to‐everything (V2X)), 2) Need for standardized or common language to improve information sharing, 3) Open data sets to support and validate technical advances and standardization across system components and areas (i.e., standards evolving in parallel with technology), and 4) Pivotal role for NIST as a convener to bring diverse stakeholders together for knowledge exchange and cross‐industry dialogue.

In consultation with ASTM and other stakeholders in Tissue-Engineered Medical Products (TEMPs) industry, the National Institute of Standards and Technology (NIST) initiated a project designed to produce Reference Material scaffolds for tissue engineering. The rationale for Reference Material scaffolds was developed through several NIST/Industry workshops. In brief, Reference Material scaffolds have multiple uses: facilitating the development and the validation of new test methods that measure interactions among various components of a TEMP; comparison with other scaffolds and scaffold materials in terms of cellular responses, biodegradation, and releases of growth factors; and comparisons of responses among various cell lines. The primary customers for Reference Material scaffolds are expected to be the TEMPs industry, academic researchers, regulators, and standards developing organizations. There are many properties of a TEMP that warrant development of multiple Reference Material scaffolds. Currently, NIST is defining a set of Reference Material scaffolds based on geometric descriptors such as permeability, pore volume, pore size distribution, interconnectivity, and tortuosity. In consultation with ASTM, NIST is testing three candidate scaffolds produced by: three dimensional (3-D) printing, stereolithography, and fused deposition modeling (FDM). Scaffolds made by these methods have been obtained from Mayo Clinic (Rochester, MN), Case Western Reserve University (CWRU) (Cleveland, OH), and Osteopore International (Singapore), respectively, for structural characterization. These prototype scaffolds, with well-defined architectures, have been selected to address the following items of interest: 1) establishment of useful functional definitions of porosity content, interconnectivity, and pores; 2) evaluation of testing methods listed in the Standard Guide for the Porosity of Polymeric Scaffolds for Use in Tissue-Engineered Medical Products, which is being drafted by ASTM. Currently, NIST and the Center for Devices and Radiological Health of the Food and Drug Administration, as well as other groups from US and foreign laboratories, are actively carrying out cross-validation test of these prototype scaffolds.

As cybersecurity issues surge, it highlights the pressing need for increased awareness. In our digitally interconnected world, where information technology underpins the lives of individuals, businesses, and even national security, the threat of cyberattacks looms large. To enhance national cybersecurity preparedness, there is a critical call to action: we must promote public awareness of cybersecurity issues and bolster the ranks of trained cybersecurity professionals. This research introduces a novel cybersecurity awareness model based on the National Institute of Standards and Technology (NIST). Its primary goal is to make NIST accessible to secondary school students pursuing ICT courses and their invaluable resource, the school counselling units. The model aims to instil cybersecurity awareness in secondary school students and guide them in choosing the most suitable higher education paths, particularly in the ICT and cybersecurity fields. The study comprises three phases. In the first phase, a systematic literature review (SLR) examines globally applicable cybersecurity education models. The second phase investigates the implementation of cybersecurity education for secondary school students in Malaysia. This includes interviews with school counselling units responsible for guiding students toward higher education and surveys of students in grades four and five enrolled in ICT courses. The third and pivotal phase focuses on developing the proposed model. It involves analysing and implementing the results of the SLR, mapping them to the NIST framework, and incorporating themes from interviews and surveys. As a tangible representation of the model, a mobile application prototype has been developed. The Cybersecurity Awareness Model empowers school counselling units to seamlessly integrate career exploration with career decision-making for secondary students at any stage of their development. Moreover, it offers a means to create strategies for after-school programs, particularly in the dynamic field of cybersecurity. This model is expected to guide students in exploring academic majors and careers, preparing for higher education post-high school, initiating internships or job searches, and adapting to a world in constant flux. In doing so, it not only empowers individuals but also strengthens the nation's resilience in the face of cybersecurity challenges.

Freezing-point black bodies used as primary standards of spectral radiance at two national standards laboratories are directly intercompared for the first time. The spectral radiance ratio is directly measured for a copper freezing-point black body from the National Research Laboratory of Metrology (NRLM), Japan, and a gold freezing-point black body from the National Institute of Standards and Technology (NIST), USA. Narrowband spectral radiance measurements at five wavelengths between 546 nm and 878 nm show the NRLM copper to NIST gold freezing-point temperature interval to be 20,39 K ± 0,12 K (2σ), in good agreement with the International Temperature Scale of 1990 (ITS-90) value of 20,44 K, and comfortably within the combined uncertainties assigned to the realization of the ITS-90 from each source.