Scientific news from division 1

The volume of silicon spheres with a mass of 1 kg could previously be measured by means of hydrostatic weighing with an uncertainty of 0.8 mm³ (k = 2). Using new and more stable thermistors to determine the temperature distribution in the measuring liquid of the fundamental weighing apparatus, a hydrostatic volume determination with an uncertainty of 0.35 mm³ (k = 2) will be possible in the...

Force and moment sensors used in a dynamic environment need to be characterized in a similar manner to the use case. For the periodic characterization of uniaxial force sensors, PTB uses an electrodynamic shaker set-up. The capability of this set-up is however very restricted for the characterization of multi-component sensors, therefore, it needs to be extended.

For the recently developed circumaural audiometric RadioEar DD65v2 headphone, reference hearing thresholds were determined for pure-tone audiometry and free-field equalization data for use in speech audiometry. For this purpose, a series of standardized auditory tests were conducted on 25 test subjects who had normal hearing. The reference data for calibrating audiometers equipped with this...

Within the scope of comparison measurements with regard to the results of the determination of the Avogadro constant and the Planck constant with the aid of the first two monocrystalline silicon spheres AVO28-S5c and AVO28-S8c [1] made of highly enriched silicon (degree of enrichment for ²⁸Si: > 99.99 %), also the mass of the spheres in vacuum was determined again.

The dynamic calibration of bridge amplifiers is an important prerequisite for the dynamic characterisation of force, pressure and torque transducers. A new calibration device based on a dynamic bridge standard developed at PTB enables these dynamic calibrations up to a frequency range of 10 kHz.

Automatic weighing instruments are an important element of industrial production and are used, for example, to check the content of prepackages. Currently, however, no specifications exist for the calibration of these instruments. Over the past three years, proposals for calibration guides for these instruments have been drafted within the scope of the AWICal project.

For the first time, torque measurement in nacelle test benches has been traced to the national standard. Common torque calibration standards only provide methods for static torque calibration. However, for torque measurement in nacelle test benches, calibration at varying rotational speeds is required. The findings and research will contribute to a reliable efficiency determination.

The quality of life experienced in rooms depends significantly on their acoustic properties. Acoustics has to fit the purpose of the room. Meeting rooms must enable the comprehension of spoken language, open-plan offices undisturbed work. Measures for appropriate room acoustics need the sound absorption of room surfaces and interior objects as a main input quantity.

When carrying out noise measurements, it is usually assumed that the directional response pattern of the microphone used can be neglected. This is true when the microphone is clearly smaller than the wavelength of the investigated sound. This usually does not apply in the case of the ultrasound range.

A procedure to measure airborne ultrasound is being developed within the scope of Ears II, an EU research project. This procedure, which is designed for occupational safety, has been developed to reliably determine the exposure of staff to airborne ultrasound at the workplace. Important findings obtained during its development were provided by sound field scans with a high spatial resolution at a...

Changes in the consumption behaviour of consumers over the years as well as progress in the state-of-the-art of domestic water metering are two of the reasons why a characterization of water meters close to real-world conditions is required today.