Abstract: The actual density of liquids is determined with a flexural oscillator that is excited at two different natural vibrations. The presence of air/gas inclusions or other inhomogeneities in a liquid is detected and their influence can be eliminated. In an initial step, the periods of the inherent vibrations and of at least one vibration damping value of the natural vibrations are determined for liquids having different densities ? and viscosities. Liquid densities as well as the difference between them and between the vibration damping values are determined from this. An inclusion-free curve (KB) which reflects the functional dependence F(??) between the relative density differences and the vibration damping differences is calculated and the exact function determined; i.e. the gas/air inclusion-free curve (KB) is expanded by introducing a deviation bandwidth (ab) to form an inclusion-free curve area (KF), which is stored.

Abstract: The actual density of liquids is determined with a flexural oscillator that is excited at two different natural vibrations. The presence of air/gas inclusions or other inhomogeneities in a liquid is detected and their influence can be eliminated. In an initial step, the periods of the inherent vibrations and of at least one vibration damping value of the natural vibrations are determined for liquids having different densities ? and viscosities. Liquid densities as well as the difference between them and between the vibration damping values are determined from this. An inclusion-free curve (KB) which reflects the functional dependence F(??) between the relative density differences and the vibration damping differences is calculated and the exact function determined; i.e. the gas/air inclusion-free curve (KB) is expanded by introducing a deviation bandwidth (ab) to form an inclusion-free curve area (KF), which is stored.

Abstract: A device for determining a physical quantity of a sample, in particular for determining the density of a fluid, is implemented as an optical measuring device which allows an evaluation the reliability of the measured value in the measurement of the physical quantity of the sample.

Abstract: An apparatus and method for determining a characteristic of a resistor and/or an environment occurring as a voltage across a measuring resistor (e.g., a voltage across a temperature-dependent resistor) by comparing it with a reference value that occurs as a voltage across a reference resistor (e.g., a voltage across a temperature-stabilized reference resistor) to determine, for example, temperature. A total of four voltages are measured. That is, positive and negative currents are passed through the measuring resistor and the resulting first and second voltages across the measuring resistor are detected. Positive and negative currents then are passed through the reference resistor and the resulting third and fourth voltages across the reference resistor are detected. The difference between the first and second voltage and the third and fourth voltages is determined to eliminate the effect of thermo-electric voltages in the lines to the resistors and the lines of the contact terminals in the switches.