Abstract: The present invention relates to a process for determining the state of an exhaust-gas purification device. The exhaust-gas purification device is one which can store gas and/or particles. By means of the proposed process, it is for example possible for the loading state of the exhaust-gas aftertreatment system, for example the oxygen storage state of a catalytic converter which is provided with an oxygen-storing material, such as for example a three-way catalytic converter, to be analyzed. The present process operates contactlessly through the analysis of resonances which arise upon the excitation of the catalytic converter using the purification device as microwave cavity resonator.

Abstract: The present invention relates to a process for determining the state of an exhaust-gas purification device. The exhaust-gas purification device is one which can store gas and/or particles. By means of the proposed process, it is for example possible for the loading state of the exhaust-gas aftertreatment system, for example the oxygen storage state of a catalytic converter which is provided with an oxygen-storing material, such as for example a three-way catalytic converter, to be analysed.

Abstract: A tool holder for holding a tool has at least one sensor for measuring an operating parameter of the tool holder or the tool during the operation thereof and generating measured value signals which are fed to a signal processing unit for evaluation. The sensor is a surface acoustic wave sensor operating according to acoustic wave principles and its measured value signals are readable in a contactless manner by means of radio waves. The surface acoustic wave sensor requires no current supply circuit but instead draws transmission energy required for transmission of the measured value signals to the signal processing unit from a high frequency interrogation signal, that is transmitted by radio waves from the signal processing unit and is received by the surface acoustic wave sensor.