Scientific news from division 1

Am Ionenexperiment konnte erstmalig eine wägbare Masse von Wismut-Ionen akkumuliert werden. Mit einem neu entwickelten Verdampferofen für die kommerzielle Ionenquelle und einer ersten Kollektorversion wurden 40 mg aufgesammelt. So konnte erstmalig die atomare Masseneinheit mit einer relativen Abweichung vom CODATA-Wert von etwa 9·10^-4 experimentell ermittelt werden.

With a high temperature stability and the possibility of adjusting the temperature of the test fluid over a wide range, the hydrodynamic test field, as a high-accuracy water flow calibration facility, offers new qualitative possibilities of more precise calibrations of measuring devices and reduces the measurement uncertainty during traceability and comparison measurements.

Mit einem neu entwickelten FSK (Frequency Shift Keying)-Verfahren kann die bei bisherigen Doppler-Global-Velocimeter (DGV)-Systemen erforderliche Referenz-kamera entfallen und die Messunsicherheit für die Geschwindigkeitsfeldmessung gegenüber konventionellen Systemen drastisch reduziert werden. Damit konnten bei reduziertem technischem Aufwand Ganzfeldmessungen instationärer...

It was shown by scaled model measurements that different frequencies of the structure-borne sound modes of a test specimen lead to an uncertainty of about 2 dB in the measured sound reduction index at low frequencies.

The resonances and disturbing motions of acceleration exciters have been investigated with the help of a 3D-Laservibrometer and a Scanning-Laservibrometer. As a consequence the influence of these disturbances on the results of primary calibration of accelerometers has been reduced largely.

After having been used for more than 17 years, the comparator balance of PTB used so far as prototype balance is replaced by a high-resolution 1 kg vacuum mass comparator of the latest generation.

The new geometrical primary standard on basis of the principle of flow comparator (which was developed in the PTB and is patented) was assembled for the flow rates between 0.02 and 4 m³/h and was prepared for the first function test. The principle has been tested very successfully in the last two years with a small prototype used for flow rates below 5 l/h. Based on the mechanical concept...

Most laboratories don't possess special test facilities for the measurement of the flanking sound reduction. Those laboratories, as a remedy, install the test object into normal test facilities. PTB examined this procedure.

The recording of spectral sound field parameters directly in the cleaning bath allows the efficiency of ultrasound-based cleaning processes to be determined and optimized.

A new set-up allows the automatisation of tests for the type approval and the calibration of sound calibrators.

A portable power standard for the traceability of measuring devices for ultrasonic physiotherapy equipment has successfully been developed and tested in an international cooperation under EU funding.

Um der PTB und den Herstellern von Geschwindigkeitsüberwachungsgeräten eine transparente Basis für die Zulassungspraxis zu liefern, wurden die bestehenden PTB-Anforderungen entsprechend dem aktuellen Stand der Technik überarbeitet. Insbesondere wurden Anforderungen an mehrzielfähige Geräte, die Anbindung an Wechselverkehrszeichen und die Verwendung von Digitalkameras spezifiziert.

A comparison of different auralisation results obtained with various room acoustic simulation tools led to large differences which can be attributed to the use of different dummy head microphones as well as to differences in the ray tracing methods and convolution algorithms.

First positive results of a joint research project of PTB and verification authorities show that in-situ water meter testing is technically feasible and serve as a basis for a corresponding extension of the existing provisions for in-service testing.

Die Hersteller, Anwender und Vertreiber von Geräten, für deren Zulassung bzw. Prüfung gemäß den o.a. §§ die PTB zuständig ist, können die entsprechenden umfangreichen und laufend aktualisierten Listen inzwischen über das Internet abrufen. Die hohe Anzahl der Abrufe (monatlich mehr als 3000) dokumentiert den großen Bedarf.

Due to a novel flowmeter for which a patent is pending, it is possible to measure the mass flow of a fluid independent of its material properties, by means of an impulse force measurement.

A novel temperature chamber in combination with a deadweight force standard machine (FSM) allows the testing and certification of load cells with nominal loads up to 200 t by the Physikalisch-Technische Bundesanstalt (PTB). This facility is unique in Europe; for the first time, it offers manufacturers and customers the possibility of certifying load cells with very high nominal loads as used...

It was found out that inside a car there is often hardly a warning effect of the siren of an approaching ambulance or no effect at all. It has to be considered that the sound pressure levels very much depend on the car. Especially in new and expensive cars great importance is attached to external sound insulation which further reduces the audibility of external warning signals which further...

In spring 2005, a CIPM Key Comparison for high-pressure natural gas was successfully completed. It turned out that only three of all high-pressure test facilities in the world were prepared and technically in a position to participate. The result of this CIPM comparison is that the reference value is identical with the harmonized European natural gas cubic metre which has been made available...

In May 2005, the first international key comparisons in the field of torque realization and torque measurement were initiated. Under the umbrella of the CIPM (Comité International des Poids et Mesures/International Committee for Weights and Measures), the best measuring facilities in the world are compared among one another to find out how well they agree and whether the measurement uncertainties...

The works on the revision of the world-wide applied recommendation "R76" of the "Organisation International de Métrologie Légale" (OIML) for non-automatic weighing instruments have already progressed far. The presumably last draft is finished in September of this year and is distributed to the members of the OIML committee for non-automatic weighing instruments for a vote.