Scientific news from division 1

The force standard machines of PTB serve to realize the unit "newton" from so far 0.5 N to 16.5 MN. To extend this measurement range towards smaller forces, a new device was put into operation. Instead of conventional weights, modern electromagnetically compensated load cells are used for traceability. This allows force transducers to be calibrated in the range from 1 mN to 2 N with known...

Das entwickelte Verfahren zur Eigenkalibrierung während eines Messvorgangs erlaubt präzise spektroskopische Geschwindigkeitsfeldmessungen ohne die sonst notwendige Vorabkalibrierung und Stabilisierung der Absorptionszellenparameter.

Hochintegrierte fasergekoppelte und abstimmbare Laserdiodenmodule aus dem Telekommunikationsbereich erlauben die Realisierung miniaturisierter Laser-Doppler-Anemometer, die durch ihre messtechnische Konzeption eine hohe Modularität für mehrkomponentige Strömungsgeschwindigkeits- und hochauflösende Geschwindigkeitsprofilmessungen aufweisen.

Gigantic mass and volume flows of gaseous and liquid media are transported and measured in the pipeline systems and filling plants of Germany, Europe, and worldwide, and sold to the ultimate consumer. In view of the outstanding economic importance of supplying gas, water, mineral oil, heat, and – lately - also refrigeration, and in view of the political discussions on energy efficiency,...

Zur Geschwindigkeitsmessung von kleinen Weltraumpartikeln wurde ein Messaufbau entwickelt, der den beim Durchflug durch eine Laserlichtebene entstehenden Lichtblitz detektiert. Erste Funktionstests mit schnellen Miniaturgeschossen wurden erfolgreich absolviert. Der Messaufbau ermöglicht durch Detektion und Auswertung einzelner Lichtblitze auch die Untersuchung von Geschossgarben.

Erstmals wurde ein modellbasiertes Konzept zur Darstellung des Momentandurchflusses einer strömenden Flüssigkeit entwickelt und mit ersten Untersuchungsergebnissen auf dem Hydrodynamischen Prüffeld belegt. Im Gegensatz zur sonst üblichen Durchflussmessung, bei der der mittlere Durchfluss über den Gesamtzeitraum einer Messung ermittelt wird, ermöglicht das neue, dynamische Verfahren erstmals die...

The 20 kN·m torque standard machine of PTB ranks among the best facilities of its kind in the world. To ensure this leading position also in the future, investigations and comparisons are performed at regular intervals. In the last few years, a small asymmetry in the arm lengths of the lever (the right arm was too short by approx. 10 µm, the left too long by approx. the same amount) has been...

When investigating building acoustical problems on downscaled models, detailed data on the mechanical properties of the used materials were needed for experimental and numerical purposes. To determine the properties such as Young's modulus and material damping a number of established measurement methods exist, partially as normative references. Unfortunately, these measurement methods usually...

The stability of the 1 kg vacuum mass comparator Sartorius CCL 1007 could be improved considerably for mass determinations in air by an additional thermal insulation. Mass determinations in air are now possible with standard deviations of less than 0.1 µg. Comparable results were achieved up to now only under vacuum conditions.

At the ion accumulation experiment the mass of accumulated ions and thereby the measurement uncertainty is governed by the value of the ion current at the collector. In order to achieve the maximal ion current with the existing apparatus simulations and measurements were performed for optimizing the parameters gas pressure and extraction voltage at the ion source as well as the transmission...

Problems in building acoustics can be investigated excellently on small, downscaled models. They are more flexible, require less time and effort and are cheaper than the usual measurements carried out in large and standardized test facilities, and they are also more reliable and realistic than most computer simulations. A downscaled model of a building-acoustics wall test facility has been...

Force standard machines generate a force vector whose direction is determined by the acceleration due to gravity. For the calibration of force vector sensors, different alignments of force vectors - in relation to the coordinate system of the force vector sensor - are required. For that purpose, a special calibration body has been developed. From the signals of the measuring channels of the...

Within the scope of a DFG research project at PTB, metal thin-film strain gauges were sputtered on force transducers, and their behaviour was investigated. In some fields of force measurement, the use of thin-film strain gauges promises advantages compared to the usually used foil strain gauges.

In August 2008, the project "Model-based calibration of accelerometers" which is supported by the Federal Ministry of Economics and Technology (BMWi), was completed successfully. The objective was to transfer to industry novel measuring procedures and methods of data analysis for the calibration of accelerometers as have been developed at PTB over the last few years.

Load cells (LCs) with single-crystal mechanical springs (MSs) and sputtered-on strain gauge (SGs), due to the ideal elastic properties of the MSs, promise a low time-dependent behaviour and a high reproducibility of the measuring signals. These sensors would thus be optimally suited for use in mechatronic systems in order to digitally compensate for further influence factors such as...

Ausbildungsmaterial über die physikalischen und technischen Grundlagen der Sonographie dient der Verbesserung der Ausbildungsqualität von Ärzten und damit der diagnostischen Sicherheit.

In June, the project "Model-based calibration of accelerometers", which is supported by the Federal Ministry of Economics and Technology (BMWi) and carried out by PTB together with SPEKTRA Schwingungstechnik und Akustik GmbH Dresden ("SPEKTRA Vibration and Acoustic Systems Engineering"), will be launched. The project is promoted within the scope of the Measurement Standards Testing and...

By the free-field reciprocity calibration of quarter-inch measuring microphones, the basis for the realization of the sound pressure unit has been created for frequencies up to 160 kHz.

With the new Gravity Information System, a novel information platform is presented on the web pages of PTB. On this platform, users from metrology can inform themselves about the local intensity of the earth’s field of gravity, related to the place of use. A four-stage gravity data model, mainly composed of freely available secondary (i.e. derived) gravitational field quantities, serves as a...

It was shown by scaled model measurements that in test facilities, homogeneous building elements have a larger sound reduction than in real buildings. This is a broadband effect which decreases with increasing frequencies and amounts up to 5 dB at low frequencies.

With the coming into force of the new Measuring Instruments Directive 2004/22/EC (MID) on 31 March 2004, Working Group 1.13 of PTB set out to prepare itself for the new development - thus already long before the planned Europe-wide implementation of this directive by 30 October 2006. At the beginning of 2005, information letters were sent out to approx. 100 manufacturers of weighing...

Since 1999 exists a German-Japanese agreement on the mutual recognition of the test results of non-automatic weighing instruments. The rapid metrological progress of the past few years in the field of weighing technology has made a revision necessary. For this reason, a comprehensive extension of the agreement has been signed on June 5, 2007 by PTB and the National Metrology Institute of...