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Abstract: Modern dielectrics used in power capacitors can exhibit a dissipation factor lower than 0.005 %, which approaches the limits of presently available measurement techniques. This article reviews techniques, apparatus, and available calibration
services for dissipation factor with regard to lowest achievable uncertainties. It is shown that further metrological advances are necessary to lower uncertainty in the measurement to levels at least five times less than presently achievable, in order
to ensure traceable and quality-assured measurement of modern dielectrics with such low dissipation factors.
Abstract: Piston gauges or pressure balances are important primary standards for the realization of the SI unit of pressure, the pascal. Because of their long-term stability, they are also used as secondary or working standards in the dissemination of
the pressure scale. The National Institute of Standards and Technology (NIST) operates and maintains a calibration service for these devices, and has recently undertaken a modernization effort. Following a preliminary investigation into the feasibility
of using transducers as instantaneous in-situ transfer standards, we now present the results of a near fully automated calibration system. This effort includes the design, building, and validation of an automated gas-handling manifold, and the development
of a new software suite. The new system demonstrates an expanded uncertainty on the order of 1 in 105, comparable to the traditional system, but offers a five-fold decrease in calibration turnaround time.
Abstract: The Standards and Calibration Laboratory (SCL) in Hong Kong has set up a calibration facility for electrocardiograph (ECG) simulators. ECGs are medical devices designed to measure the electrical signals associated with cardiac activities. They
are used to diagnose heart diseases and arrhythmias, and are commonly used in hospitals, emergency facilities, and medical institutes. Routine performance check of ECGs could be performed by ECG simulators. To ensure the accuracy of ECGs, traceable
calibration to SI units is essential. At the SCL, the output signal from an ECG simulator is measured by a differential amplifier and a high-speed digital sampling system. The digital sampling system enables the calibration of non-sinusoidal signal
with high accuracy. Signal characteristics including signal amplitude, frequency, and wave shape could be evaluated by an in-house developed program for normal sinus rhythm waveforms as well as for performance waveforms.
Abstract: This article describes the calibration system developed by the Standards and Calibration Laboratory (SCL) for calibrating single mode optical time domain reflectometers (OTDR) fitted with FC connectors at wavelengths of 1310 nm and 1550 nm
in accordance with the international standard IEC 61746-1:2009. The parameters calibrated include distance deviation, attenuation deviation, and reflectance deviation. The principle of the calibration is to compare a set of reference standards, namely
a distance calibration artifact, an attenuation calibration artifact, and reflectance calibration artifacts against the measured values by the OTDR under test. The expanded measurement uncertainties with 95 % level of confidence for the distance,
attenuation, and reflectance deviation calibration are 2 m, 0.04 dB, and 1.7 dB, respectively.
Abstract: The National Institute of Standards and Technology (NIST) has provided remote frequency and time calibration services to customers for more than three decades. These services continuously compare a customer’s primary frequency and/or time standard
to the coordinated universal time scale kept at NIST, known as UTC(NIST), which is the national standard for frequency and time in the United States. The remote calibration services differ from traditional calibration services in at least two important
ways. The first difference is that the customer does not send the device under test to NIST. Instead, NIST sends equipment to the customer that automates the measurements and returns the results via a network connection. The second difference is that
the calibration never stops. New measurement results are recorded 24 hours per day, 7 days a week. This allows customers to continuously establish traceability to the International System (SI) units via UTC(NIST) without disturbing or moving their
standard. This paper discusses the reach and impact of the NIST remote frequency and time calibration services by describing how they work, their calibration and measurement capabilities, their quality system, and the requirements of the customers
that they serve.
Abstract: By leveraging the stroboscopic effect, a new method, namely the Stationary Counting Method, has been developed at the Standards and Calibration Laboratory (SCL) of Hong Kong for calibrating the frame rate of digital video recorder using a special
synchronous counter designed by SCL. The frequency of the clock signal fed to the counter is traceable to the SI through the Cesium Beam Frequency Standard maintained in SCL. The target devices include high speed digital cameras, smartphones, closed
circuit televisions (CCTV), and car cameras. It is common for vehicles to install car cameras to capture the moment when unexpected incidents occur. The recorded videos might be tendered as evidence in legal proceedings and accident investigations.
Therefore, the accuracy of the frame rate is extremely important. In addition, the proposed method can be used to find the time duration as well as the occurrence of skipped or extra frames in the video recorded by a digital camera.
Abstract: The geometry of the endface is a key factor for controlling the performance of the connector, specifically to determine which areas come into contact when the two connectors are mated. For single-fiber, physical contact (PC) endface fiber-optics,
the radius of curvature, apex offset and spherical fiber height are the geometrical parameters of interest. Measurement of these endface parameters provides quality control and quality assurance after the polishing process has been concluded. The
International Electrotechnical Commission (IEC) has a series of standards to aid in the basic testing and measurement procedures associated with fiber-optic interconnecting devices and passive components; however, no specific standard for evaluating
the uncertainty associated with these measurements is available. Furthermore, due to the industrial competitiveness of the manufacturing product, most literature is for internal-use only or is considered proprietary information. The purpose of this
research is to investigate possible error sources that contribute to the overall uncertainty of the measurement process and to quantify an estimate of the expanded uncertainty for the geometrical parameters of a single-fiber, PC endface fiber-optic
cable.
Abstract: The findings presented in this paper are a result of unclassified literature research of different types of biosensors within a larger context of biological warfare. This paper discusses different technologies being used in designing more efficient
biosensors for the U.S. Navy that adequately match the requirements of variable military environments. Finally, this paper discusses the vital requirements of measurement and calibration techniques of these sensors to maintain accuracy and safety
for our warfighters. Based on unclassified research, biological agents’ use in biological warfare is a burgeoning stratagem in a new world of rogue terrorist organizations. The Navy must have an effective response protocol involving biosensor technology
to have a secure future at home and abroad.
Abstract: We report a software and hardware solution for collection, wireless transmission, and storage of measurement data (logIT). logIT allows end-users with only elementary knowledge of engineering and coding the ability to rapidly obtain the necessary
components to automatically record and wirelessly transmit GPS coordinates and data sensed by a measurement device with approximately one-minute temporal resolution. The platform is flexible and can be used with any hardware or sensor that reports
a voltage. Two codes are provided within this manuscript. First, we present code for data logging within a Thingspeak.com channel. Secondly, we present code for data logging to an independent Apache server administered by the end-user. Within the
article, we demonstrate two example applications in which light levels are measured and reported wirelessly during a volunteer’s walk through our campus, and for mobile measurements of airborne dust levels in Lubbock, TX. We envision the codes provided
within can be used to enable and enhance a large variety of research projects within the measurement community.
Abstract: This article demonstrates the essential procedures in the Hong Kong Standards and Calibration Laboratory for the calibration of an electrostatic discharge (ESD) generator in accordance with the International Standard IEC 61000-4-2 Edition 2.0
(2008–12) on electromagnetic compatibility. All the required instruments and special precautions to perform the calibration are listed clearly. The performance of an ESD generator has been tested and reported by following the requirements of the standard.
The corresponding results, including the waveform parameters of the current discharge pulse and the DC high voltage test of the ESD generator before discharge with different voltages setting, are reported. The determination of uncertainty components
is a critical factor for achieving an accurate measurement result. The measurement uncertainties of the calibration are suggested and clearly listed in this paper, and they are evaluated in accordance with the document “Guide to the Expression of
Uncertainty in Measurement (GUM).” The expanded measurement uncertainty U, with level of confidence of approximate 95 % probability is used in the calibration.
Abstract: The GUM Supplement 2 describes a Monte Carlo Method (MCM) for evaluating measurement models with more than one output quantity. Such models are common in electrical metrology where the measurands may be complex-valued quantities, such as S-parameters.
The Standards and Calibration Laboratory (SCL) developed a software tool six years ago in accordance with GUM Supplement 2. The SCL software tool was written in Visual C++ and Visual Basic for Application (VBA), with Microsoft Excel as front-end user
interface. As MCM involves large numbers of repetitive computations, this old software tool has a long processing time, especially for complicated measurement models. Nowadays many personal computers are equipped with a graphics processing unit (GPU)
containing up to thousands of floating point cores. As MCM is well suited to parallel processing, SCL has ported the algorithm to a GPU using the Open Computing Language (OpenCL). The new tool is an add-on module to Microsoft Excel. GPUs from the
major suppliers Nvidia, AMD and Intel are supported. The uncertainty computation time may be reduced significantly. This paper describes the design and implementation of this new software tool.
Abstract: Centro Nacional de Metrología (CENAM, Mexico) and Physikalisch-Technische Bundesanstalt (PTB, Germany) provide the dissemination of the International Temperature Scale of 1990 (ITS-90) in their respective countries. Presently, CENAM has a declared
calibration and measurement capability of radiance temperature from 50 °C to 400 °C for wideband radiation thermometers, and it has been working to extend its services in the low temperature range below 0 °C. The calibration and measurement capability
of radiance temperature from −60 °C to 3000 °C is well established at PTB. For this radiance temperature comparison, a high-grade transfer radiation thermometer was used. It was calibrated at PTB against a water heat pipe blackbody and an ammonia
heat pipe blackbody. The temperature of each blackbody was measured with a standard platinum reference thermometer (SPRT), so the radiance temperature measurements were traceable to the ITS-90. The radiation thermometer was calibrated at CENAM against
a gallium fixed-point blackbody and a variable temperature bath blackbody whose temperature was measured with a calibrated SPRT. The description of the experimental setups used and the measurement results in the −25 °C to 100 °C temperature range
are presented. The radiance temperature results obtained at CENAM and at PTB show a good agreement within the estimated uncertainty budget.
Abstract: Calibrated values of many devices exhibit predictable drift over time. To provide an uncertainty statement valid over the entire calibration interval, one must account for drift. In this article, a method of accounting for drift is proposed
based on guidance in the Guide to Expression of Uncertainty in Measurement. An additional uncertainty term is computed using a linear regression of historical measurement data, which is included along with the time-of-test uncertainty. This method
is evaluated by analyzing its average out-of-tolerance (OOT) rate using a Monte Carlo simulation, which results in the desired 5 % average OOT rate when the total uncertainty is expanded to a 95 % confidence interval.
Abstract: When reporting the result of a measurement, the Guide to the Expression of Uncertainty in Measurement (GUM) makes it clear that a complete result includes a measured value and an associated value of uncertainty. Measuring instruments compute
and then indicate a measured value, but many, if not most instruments provide no indication of the measurement uncertainty. This leaves the metrologist to compute the uncertainty, incurring two parallel computation paths. One path is through the measuring
instrument, the other managed by the metrologist. It is feasible to merge these two paths where the instrument computes the uncertainty. This positively impacts the metrologist’s workflow. This article takes a previously reported measurement as a
use case and compares the metrologist’s workflow when using measuring instruments that report measurement uncertainty and using instruments that do not. The comparison shows that using instruments that report measurement uncertainty significantly
improves metrologist efficiency, leads to better estimates of uncertainty and, facilitates enhanced methods of managing and monitoring measurement processes.
Abstract: Residual current devices (RCDs) are commonly used in low voltage electric power systems, including our households, as protective devices against electric shock. They monitor the balancing current between the live and neutral terminals and will
trigger the relay to disconnect the load from the power line when a leakage current is detected. The functional test of RCDs may be performed by an RCD tester, which emulates a residual leakage current between the live and the earth terminals, and
to measure the tripping time of RCDs under different defined test scenarios. At the Standards and Calibration Laboratory (SCL), a traceable RCD tester calibration system was developed in-house. With the application of digital sampling techniques,
all the major functions of RCD tester may be calibrated, including: trip time, AC residual current, residual pulsating DC current with a superimposed DC current and AC residual current in a stepwise ramp-up pattern. The system uses an adjustable earth-current
leakage relay, which provides an easy way to test a wide range of trip time and residual current. The in-house developed delay circuit supports the testers designed for S-type RCD testing. A bank of non-inductive resistors is available for accurate
and traceable calibration of residual current. Details of the developed system and the associated uncertainty evaluation are presented in the paper.
The Importance of Establishing a Very High-Temperature Radiation Thermometry Measurement Capability at the National Metrology Institute of South Africa (NMISA)
Abstract: The ITS-90 scale above the Silver (Ag) point is realized using a standard linear radiation thermometer by measurement at a reference point which is an Ag, Gold (Au), or Copper (Cu) point. The fixed-point measurement at the Cu point coupled
with relative responsivity, nonlinearity and range ratio measurement is used in the scale realization above the Cu point through extrapolation based on Planck’s Law. The uncertainty of the scale above the Cu point increases as the square of the ratio
between measured and reference temperatures at very high temperatures. Since extrapolation above the copper point involves a significant source of uncertainty, it makes measurement in the high temperature range less accurate and less reproducible.
At present, radiation thermometry deals with blackbody sources at working temperatures up to 3500 °C. In order to decrease the uncertainty, new types of fixed points are being investigated and found to be effective. The assigning of fixed-point temperatures
to some of the suitable high-temperature fixed-point cells is completed. This development leads to the era of low uncertainty measurement at a very high temperature range. In this paper, the importance of developing such measurement capability at
NIMSA is demonstrated.
Developing an Integrated Approach for the Performance Verification for Large Coordinate Measuring Machines (CMM) at the Standards and Calibration Laboratory (SCL)
George C. W. Tang , Zoie W. Y. Tse, Henry K. L. Chiu
Abstract: To support local industries, the Standards and Calibration Laboratory (SCL) in Hong Kong has developed a performance verification service for Coordinate Measuring Machines (CMM) meeting the requirements of ISO 10360-2:2009 (“the ISO standard”).
In the ISO standard, a non-contact laser-based approach may be used in generating long test lengths. In that approach, additional measurement steps for an artifact with a normal coefficient of thermal expansion (CTE) (“Requirement A”) and bi-directional
measurements (“Requirement B”) are required. When the time and effort spent on the laser alignment are taken into consideration, using the laser-based approach with a laser interferometer for on-site CMM verification might not be justified. To address
these issues, SCL has developed an integrated approach. In this approach, most of the test lengths are measured with a step gauge. For test lengths exceeding the coverage of the step gauge, the step gauge is first fitted and the step lengths measured.
Test lengths longer than the step gauge are then measured using laser interferometer. The benefit of such approach is three-fold. First, Requirement A may be fulfilled by measuring a longer distance that the step gauge provides. For Requirement B,
any of the 20 mm step lengths on the step gauge may be used in lieu of the short gauge block. Second, the step gauge may guide the fitting of the laser optics thereby greatly minimizing the alignment time and effort, in particular for retro-reflectors
on some measuring heads that do not support automatic angle setting. Finally, since the measurements for Requirements A, B, and the unidirectional laser interferometer measurements all lie on the same axis, they may be cross-checked to minimize any
setting and cosine errors. The approach might promote the use of the ISO standard by not just complying with its requirements but also providing a more effective, comparable, and rigorous way in carrying out the CMM performance verification.
