Scientific news from division 1

Within the scope of the European research project EMRP IND09 "Traceable Dynamic Measurement of Mechanical Quantities", the approach of the model-based dynamic calibration of force transducers by using shock excitation has been investigated. The dynamic behaviour of force transducer and measuring device is described by models whose characteristic parameters are to be identified from the measurement...

For the dynamic calibration of force transducers, the approach of the model-based calibration is followed. The model parameters of the force transducer which characterize the dynamic behaviour are to be determined from dynamic measurement data. To excite the transducer’s resonance frequencies sufficiently strong by using shock excitation, a pendulum shock with smaller impact masses was...

As part of the European Metrology Research Programme EMRP, methods for the dynamic calibration of torque transducers have been developed within the scope of the joint research project IND09 "Traceable Dynamic Measurement of Mechanical Quantities" [1]. The research objective is the development of procedures to determine the dynamic behaviour of torque transducers by means of a model-based...

As part of the European Metrology Research Programme EMRP, new methods for the dynamic calibration of torque transducers have been investigated within the scope of the joint research project IND09 "Traceable Dynamic Measurement of Mechanical Quantities" [1]. For this purpose, a model-based description of the torque transducer to be calibrated has been developed which requires modelling of the...

When ultrasound is used for therapeutic purposes, much higher acoustic output power is generally needed than for diagnostic applications. Therefore, necessarily high electrical input power often causes a temporal change in the characteristics of the ultrasonic transducer as the transducer is heated. Currently, a reference setup with selected devices and a feedforward control software has been...

Depending on the underlying model, measurement uncertainty calculations can entail the most diverse requirements. A number of commercial – but also of several free – software packages are available for this. By means of free mathematics packages (in this case, the program package "Maxima" will be used as an example) and some programming work, their functionality can be combined with the best...

Airborne ultrasound can be emitted with a very strong directivity by sound sources such as ultrasonic cleaning baths or welding equipment. Due to this focusing, very high and hearing-damaging sound pressure levels may occur locally. A new measuring arrangement now allows the emissivity of various sound sources to be determined with high resolution and with level accuracy.

Um große Kräfte bis 16,5 MN mit kleinsten Messunsicherheiten zu realisieren, werden die Gewichtskräfte von Belastungsmassen über hydraulische Kolben-Zylinder-Systeme auf große Kräfte übersetzt. Die Rückführung erfolgt einerseits über die Gewichtskräfte, die sich aus der Masse der Belastungskörper, der Auftriebskorrektur und der wirkenden Erdbeschleunigung ergeben, und andererseits über die...

Ein neu entwickeltes Lidar-System erlaubt die vektorielle Bestimmung der Windgeschwindigkeit anhand des Streulichts einzelner Aerosole innerhalb eines räumlich hochaufgelösten Messvolumens in Höhen von 5 m bis über 200 m mit einer Geschwindigkeitsauflösung von 0,1 m/s. Im Gegensatz zu konventionellen Wind-Lidar-Systemen, welche für die präzise Messung des Windvektors nahezu homogene...

The spatial resolution of commercial LDA systems for the measurement of local flow velocities in gases and liquids is in the range of 1 mm to 10 mm and is given by the length of the intersection volume of the crossing laser beams. In the context of the cooperation project "Zentrales Innovationsprogramm Mittelstand" (ZIM) a measurement principle developed at PTB was implemented in a compact profile...

Impact sound reduction is the main acoustical parameter for floor coverings. According to ISO 10140 it is determined by using a special test facility consisting of two vertically aligned rooms with a minimum volume of 50 m³ each. Building and keeping such a test facility available is unprofitable for smaller enterprises, because of the specific requirements which have to be fulfilled. The compact...

The reliable measurement of static torques plays a major role in many fields of work. The reason for this is that – besides the measurement of reaction torques – it is still the basis for torque measurement in the rotating and often also in the dynamic application. The unit is disseminated from PTB via accredited laboratories to the end user. Good results of comparison measurements between the...

The transmission quality of public address systems is evaluated by means of the Speech Transmission Index (STI) that essentially describes the goodness of modulation transfer (DIN EN 60628-16). An STI value of 0 corresponds to a total loss of signal modulation, whereas an STI value of 1 represents ideal signal transmission. For emergency warning systems an STI value ≥ 0.5 is required, which...

The ability of buildings to insulate impact sound excitation (e.g. the walking around of human beings) is characterized metrologically in such a way that a small tapping machine is used as excitation and the generated sound pressure ("standard impact sound level") is determined in the respective room. However, this method ignores the mechanical interaction between the source and the excited...

Contrary to general opinion, the hearing of infrasound (f < 16 Hz) is possible and leads to distress which differs from person to person. However, the mechanisms of this auditory perception by human beings are still largely unexplained. Within the scope of the European research project "EARS", these mechanisms are to be investigated in detail by means of objective procedures of medical...

Noise at low frequencies is constantly increasing. The characteristic quantity for protection against noise – the sound reduction index – has, however, not been defined for this range. It has therefore been investigated as to whether it is nevertheless applicable to low frequencies.

After cataract surgery, damage to endothelial cells located on the internal side of the cornea is observed in the majority of patients. The causes of this cell damage have not yet been fully clarified; this can affect the corneal dehydration for which these cells are responsible. The – in this case – reduced performance of the endothelial cells leads to a temporary swelling of the cornea in the...

Die Qualität von Vergleichsmessungen wird wesentlich von den Eigenschaften der verwendeten Transfernormale bestimmt, deren Messstabilität unmittelbar in die Berechnung des sogenannten Standardized Degree of Equivalence (E_N) eingeht. Auf dem Gebiet der Flüssigkeitsmessung sind hierbei insbesondere Temperatur- und Druckanhängigkeit, Wiederhol- und Vergleichpräzision sowie die Drift des Messgerätes...

For the first time, the OIML Project Group "Dynamic Volume and Mass Measurement" has developed worldwide uniform test procedures and a uniform documentation of the respective test results for measuring systems for liquids other than water.

Die CMC-Einträge der PTB für Durchflussmessung mit atmosphärischer Luft wurden in zwei internationalen Ringvergleichen auch bei Verwendung eines neuen Primärnormals mit verringerter Messunsicherheit von 0,045% eindrucksvoll bestätigt.

Die Darstellung und Weitergabe eines harmonisierten Kubikmeters im Bereich der Volumenmessung von Erdgas unter hohem Druck wird mit nunmehr vier Partnern auf vertraglich neu gestalteter Basis fortgesetzt.