Scientific news from division 1

After completion of the reconstruction work and the general start-up of the petroleum test rig, all important subassemblies have now been investigated in detail with respect to their concrete influence on the measurement uncertainty of the test rig – in particular also the influence of the flow diverting mechanism on the newly realized flying start-stop operation.

The installation in a pressure-resistant enclosure allowed the standard deviation of a 10 kg mass comparator to be reduced from 20 µg to approx. 4 µg.

The Working Group "Speed Measuring Instruments" is equipped with several reference facilities which are used to test speed-monitoring devices within the scope of the type-approval certificate of these instruments. The objects to be tested have to comply with the maximum permissible errors in service laid down in the Verification Ordinance (i.e. ± 3 km/h in the case of measured values of up to...

It was possible to successfully conclude the research work on the optical flow rate standard with measurements of the boundary layers for flow rates up to 1600 m³/h. The examination has shown the same dependence on the Reynolds number for both the large and the medium nozzle and their consistent characteristic. Thus with the optical standard, an independent method has become available for the...

An evaluation of many interlaboratory tests yielded the result that there was no noticeable change in the uncertainty of single number descriptors in building acoustics through the inclusion of the frequency bands from 50 to 80 Hz and 4 and 5 kHz, even though these bands are considered to have the largest uncertainties.

Reliable and highly detailed information on traffic is becoming increasingly needed in order to make decisions in traffic, urban and environmental planning. For this, automatic systems are optimal. A large number of various recording systems is commercially available to acquire the required data. The advantages and disadvantages of the measurement principles used in these detection and recording...

Within the EURAMET Project 827: „LDA based intercomparison of Anemometers” a Laser-Doppler-Anemometer (LDA) has for the first been used as a transfer standard in international comparison measurements. The LDA-measurement results enabled to verify the traceability of each involved national metrology institute for the unit flow velocity as well as to determine a reference value with the up to now...

A collaboration of the working groups ”Acceleration” and ”Terahertz Optics” of PTB realized the first experimental determination of the combined electro-optic delay of PIN photo diodes with integrated preamplifier. The results from these measurements confirm the estimates of measurement uncertainty for the primary phase calibration of accelerometers especially for high frequencies.

Für die Kalibrierung mit kleinen Kräfte im µN-mN Bereich kann das Prinzip der Krafterzeugung mittels Massestapel nicht mehr oder nur noch bedingt angewendet werden. Das Problem kann durch eine Vergleichskalibrierung mittels elektromagnetisch kompensierter Waagen als Vergleichsnormal gelöst werden.

Bei der periodischen Kraftkalibrierung wird ein Kraftaufnehmer mit einer zusätzlichen Masse versehen und auf einem elektromagnetischen Schwingerreger (Shaker) zu Sinusschwingungen angeregt. Ziel der Kalibrierung ist die Messung der dynamischen Sensitivität, welche das Verhältnis aus dem Ausgangssignal des Kraftaufnehmers zur einwirkenden dynamischen Kraft darstellt.

Common procedures for the determination of the uncertainty of measurement results usually use a model function by means of which the contributions to the total measurement uncertainty are calculated. For this purpose, the partial derivatives of this mathematical function are formed which indicate - as so-called "sensitivity coefficients" - how strongly the individual contribution enters into the...

According to the Units and Time Act, PTB's task is, amongst other things, to disseminate the legal units. This task is fulfilled with the support of accredited laboratories. Since 1 January 2010, the accreditation of these calibration laboratories has been the responsibility of the Deutsche Akkreditierungsstelle GmbH (DAkkS - the German accreditation body). Pursuant to DIN EN ISO/IEC 17025,...

Ultrasonic baths are widely used in industry, in manufacturing and in the domestic field. The construction of an instrument for a specific application has to this date, however, been based on long test series and on individual empirical values of the manufacturers. The reason for this is that the underlying physical effect – cavitation – is, by nature, highly stochastic and depends on a whole...

Due to internal shifting processes, torque transducers react only slowly to a changing of loads. After a change has been effected, it takes several minutes until the output signal goes asymptotically into a stable state (Figure 1). If one wants to assess the suitability of a torque transducer for dynamic or high-precision tasks, this behaviour - which is called "creep" - must be known. For that...

In the field dynamic force measurement, a measuring device for the primary calibration of force transducers subjected to shock forces up to 250 kN has been developed and commissioned. The measuring device extends the calibration capability of the existing 20 kN shock force measuring device more than one magnitude and is especially suited to large and heavy force transducers used in the industrial...

Im Rahmen eines gemeinsamen Forschungsvorhabens von PTB und der deutschen Wasserzählerindustrie wurden umfangreiche Untersuchungen an mechanischen Wasserzählern vorgenommen, um deren Messverhalten bei wechselnden Durchflüssen und kleinen Entnahmemengen besser analysieren, vergleichen und bewerten zu können.

The minimum target size for power measurements in focussed ultrasonic fields with circular symmetry has been computed; such fields occur in medical diagnostics and in high-intensity therapeutic ultrasound applications.

The human ear is not a passive sensory organ: If a healthy ear is stimulated by two pure tones that are a musical minor third apart, it responds by producing the fundamental of the major triad. This inaudible tone which originates from the inner ear is called a distortion product otoacoustic emission, or simply a "DPOAE", and can be both elicited and recorded by a small probe inserted into the ear...

When using pulsed HIFU (High Intensity Focused Ultrasound), shear waves are radiated which contain information on the process of the formation of lesions. These can be used to monitor the progress of the therapy for the early detection and avoidance of irregularities.

Vom 11. bis 14. Oktober 2011 fand die 46. Sitzung des Internationalen Komitees für gesetzliches Messwesen (CIML) in Prag statt. Knapp 150 Teilnehmer aus 59 Mitgliedstaaten waren vertreten. Zur deutschen Delegation gehörten neben dem Autor auch Dr. Heinz Wallerus, Leiter der deutschen Akademie für Metrologie (DAM) und stellvertretender Leiter des Bayerischen Landesamtes für Maß und Gewicht (BLMG)....

Neue messtechnische Erkenntnisse, neue Materialien und verbesserte Kompensationsmechanismen sowie die neuen Entwicklungen auf dem Gebiet  digitaler Wägezellen erfordern eine Revision der OIML-Empfehlung R60 für Wägezellen.

The results of an international comparison measurement ("Key Comparison") for the mass determination of mass standards with nominal values between 200 mg and 2 kg have been published this year. All measurement results determined by PTB agree with the reference values within the measurement uncertainties stated.

Every two years, the representatives of the 14 CIP member states meet on the occasion of a full assembly which is held for several days. Germany is part of the 12 European member states. Based on multilateral state treaties and agreements, all signatory countries have committed themselves to carrying out the testing and approvals of firearms, ammunition and powder-actuated tools according to the...