621.3 Elektrotechnik, Elektronik
Refine
Year of publication
Document Type
- Article (24)
- Conference Proceeding (20)
- Book (5)
- Doctoral Thesis (2)
- Bachelor Thesis (1)
- Part of a Book (1)
- Part of Periodical (1)
Language
- English (27)
- German (24)
- Multiple languages (3)
Is part of the Bibliography
- no (54)
Keywords
- GaN (1)
- Gallium (1)
- Halberzeugnis (1)
- Hochtemperatur (1)
- InGaN (1)
- Indium (1)
- Inprozesskontrolle (1)
- LED (1)
- Licht emittierende Dioden (1)
- MOVPE (1)
Institute
- Fachbereich 4 - Institut Mess- und Senstortechnik (54) (remove)
Velocity Approximation of Hot Steel Rods Using Frequency Spectroscopy of the Cross-Section Area
(2019)
In this work, an approach for velocity approximation of hot steel rods based on frequency spectroscopy is presented. For this purpose, a sensor already implemented in a rolling mill for measuring the cross-sectional area of the rolling stock is used to obtain information about the velocity of the hot rods. Moreover, the effect of forward slip is briefly discussed.
The development of innovative measuring technology for process optimization in hot rolling mills becomes more and more relevant because of increasing demands on product quality. Measurement technology for high-resolution non-contact cross-sectional area measurement has shown that the variation in cross-sectional area contains information about the rolling process. This information can be used for the development of new measurement devices and analytical methods for process optimization. The harsh environmental conditions and strict safety regulations result in great effort when implementing a new sensor prototype in hot rolling mills. For this reason, this work presents a mechatronic test stand that can simulate the cross-sectional area variation under laboratory conditions realistically.
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.
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.
Bipolar electrosurgical systems are used for the treatment of benign prostatic hyperplasia (BPH) in urology. In order to analyse electrothermal processes during surgery the power loss density distribution around a bipolar resectoscope is calculated out of the measured potential distribution in isotonic saline solution ex situ. During further analysis power loss density values act as input for the Penne's bioheat equation. To achieve results, which are as realistic as possible, a method to obtain power loss density values, depending on the observed tissue or medium in the operating field, is presented. Applying this method, the power loss density distribution in isotonic saline solution at 25 °C is compared to the distribution calculated for the average conductivity of biological tissue in the region of interest.
Detection of air trapping in chronic obstructive pulmonary disease by low frequency ultrasound
(2012)
Background: Spirometry is regarded as the gold standard for the diagnosis of COPD, yet the condition is widely underdiagnosed. Therefore, additional screening methods that are easy to perform and to interpret are needed. Recently, we demonstrated that low frequency ultrasound (LFU) may be helpful for monitoring lung diseases. The objective of this study was to evaluate whether LFU can be used to detect air trapping in COPD. In addition, we evaluated the ability of LFU to detect the effects of short-acting bronchodilator medication.Methods: Seventeen patients with COPD and 9 healthy subjects were examined by body plethysmography and LFU. Ultrasound frequencies ranging from 1 to 40 kHz were transmitted to the sternum and received at the back during inspiration and expiration. The high pass frequency was determined from the inspiratory and the expiratory signals and their difference termed F. Measurements were repeated after inhalation of salbutamol.Results: We found signi ficant differences in F between COPD subjects and healthy subjects. These differences were already significant at GOLD stage 1 and increased with the severity of COPD. Sensitivity for detection of GOLD stage 1 was 83% and for GOLD stages worse than 1 it was 91%. Bronchodilator effects could not be detected reliably.Conclusions: We conclude that low frequency ultrasound is cost-effective, easy to perform and suitable for detecting air trapping. It might be useful in screening for COPD