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Mobile Walzenmesstechnik
(2003)
The harmonic and interharmonic analysis recommendations are contained in the latest International Electrotechnical Commission (IEC) standards on power quality. Measurement and analysis experiences have shown that great difficulties arise in the interharmonics detection and measurement with acceptable levels of accuracy. In this paper, the spectral leakage problems of the discrete Fourier transform due to synchronization errors of interharmonics are analyzed. The time-domain averaging is investigated for the processing of harmonics in the framework of the IEC standards. A difference filter is proposed to detect interharmonics and can be compatible with the IEC standards. Simulations and the field results show the usefulness of the proposed methods.
Methods of red-hot rod shape testing require a robust non-contact measurement principle as a touch point could lead to damages to the rod and the detection unit. Therefore a new basic approach based on high frequency eddy current (HFEC) has been investigated. Due to the robustness and the ability to determine the rod shape even above the Curie temperature this principle is especially well suited and can be implemented in the production process directly. The first automatic measurement setup was successfully developed with promising results. Hereby a defect of ovality was detected with a parallel RLC-oscillator. The capacity of this RLC-oscillator is constant whereas the inductance is the measurement part that varies due to eddy current interactions with the rod.
For the rod shape measurement of hot rolled round steel bars (rods) the high frequency eddy current method is especially well suited as it requires no contact point and is not limited to below the Curie temperature. Defects of the rod's shape can be detected by measuring the impedance spectrum of the RLC-oscillator. In the first laboratory setup an Agilent impedance analyser was used for initial tests. Nevertheless, this setup cannot be applied in a steel plant due to the difficult environmental conditions. Hence, a vector network analyser for passive impedance measurement that is applicable in these surroundings was developed.
Fat content of liver is an essential parameter to decide whether a liver is suitable for transplantation or not. The determination of fat content is often challenging and usually there is not enough time to bring a specimen to a pathologic laboratory. That is why transplantation clinics need a technique to measure the fat content of a graft. In this paper the theoretical basics and an existing laboratory setup are presented.
The production and deformation of perforated sheets introduces high levels of mechanical stress into the material. In a significant fraction, such stress levels lead to crack formation in the processed sheets. Additionally, the material might be thinned and weakened in the exposed areas; these areas tend to crack at any later dates. Currently no measuring device for the detection of such material cracks or narrowing in perforated sheet metals is in practical use. Such device should be able to test the deformed circumference of the processed sheets within the very limited time of the production cycles. This paper describes the physical principles and a metrological implementation of a potential method for fast crack detection in perforated sheet metals. Even a critical material thinning - prior to the formation of a crack - can be observed. The measuring task appears to be solvable on the basis of high frequency electromagnetic fields.
The transurethral resection (TUR) is a standard technique in urological treatment procedures. Both, monopolar and bipolar electrosurgical systems, are used for TUR. Whereas electrical and physical processes in surgery surroundings are well understood for monopolar systems, there is no sufficient data base for the assessment of the processes with the use of bipolar systems. In this context a multi-electrode measuring system was developed to visualize the spatial potential distribution around bipolar electrosurgical devices as a first step to risk analysis. To simulate the anatomic surroundings of a transurethral surgery a cylinder filled with isotonic saline solution was used as a complexity reduced experimental environment.
The transurethral resection (TUR) is a standard technique in urological treatment procedures. Both, monopolar and bipolar electrosurgical systems, are used for TUR. Whereas electrical and physical processes in surgery surroundings are well understood for monopolar systems, there is no sufficient data base for the assessment of the processes with the use of bipolar systems. In this context a multi-electrode measuring system was developed to visualize the spatial potential distribution around bipolar electrosurgical devices as a first step to risk analysis. To simulate the anatomic surroundings of a transurethral surgery a cylinder filled with isotonic saline solution is used as a complexity reduced experimental environment. Investigations about time stability and a qualitative assessment of the experimental set-up show deviations of measured values less than 5%. This is sufficient for further analysis of calculated power loss density distributions based on measured potential distributions. The spatial potential distribution around a bipolar devices is presented by horizontal and vertical sections through the experimental environment.