Since 2011 gasoline is blended with bioethanol (5–10 Vol.-%) to comply with the biofuel quota required by law. To examine the influence of the bioethanol additive on the functionality of the fuel vapour restraint systems a suitable test facility is designed. This test facility enables automated long-term tests lasting several weeks. As a result, the adsorption behaviour of the activated carbon filters is examined by the used sensors for multiple ad- and desorption cycles even in case of multicomponent mixtures.

December 17, 2019

Stray light autocorrelation for the measurement of ultrashort laser pulses

Anne-Sophie Rother, Peter Kohns, Georg Ankerhold

Page range: 312-322

Abstract

Ultrashort laser pulses in the femtosecond range are of growing interest in medicine and micro material processing for industrial applications. The most interesting parameter is the pulse duration, which can only be measured by optical autocorrelation methods incorporating an optically nonlinear medium. Established methods mostly use monocrystalline beta barium borate (BBO) in transmission, exhibiting a high nonlinear conversion efficiency. However, this material is brittle, expensive and sophisticated in adjustment due to the necessary non-collinear phase matching. Since fiber-based high energy femtosecond laser systems become more and more achievable, the conversion efficiency of the nonlinear medium should no longer be seen as the restricting factor. Therefore, this research work discusses the suitability of several nonlinear media with differing translucency. Quartz, ammonium dihydrogen phosphate (ADP) and aluminum nitride (AlN) were compared in a standard autocorrelation setup and a novel versatile setup measuring frequency-doubled stray light. Best results were achieved with AlN, which appears to be a suitable and promising alternative material to BBO, reducing the expenses by two to three orders of magnitude.

January 18, 2020

Using an artificial neural network to evaluate the hull condition of naval vessels

Christian Thiel, Kevin Neumann, Claas Broecheler, Frank Ludwar, Andreas Rennings, Jens Doose, Daniel Erni

Page range: 323-331

Abstract

The evaluation of the hull condition of naval vessels is a crucial part for corrosion protection systems due to the direct linkage between the electrochemical process at the hull/water interface leading to corrosion and the overall coating of the hull to prevent the corrosion process. In the case of the latter, the condition is unknown while the vessel is on a mission and either has to be evaluated by divers (in open water) or on dry docks which is a time consuming process, respectively. In our work, we present a methodology to localize coating damages without the need of divers or dry docks using an artificial neural network (ANN) combined with the information provided by the onboard impressed current cathodic protection (ICCP) system to predict said damages in a specific sector of a generic ship model. Using only the ICCP currents as highly aggregated input variables for the ANN, approximately 86 % of randomly sized and positioned coating damages are correctly predicted.

January 28, 2020

Summary of developing a test stand for realistic emulation of the cross-sectional area variation of hot rolled wire

Generation of a measurement signal with patterns, which are comparable to those of the cross-sectional area variation of a hot wire, in order to test new measurement techniques and evaluation methods for production process optimization

Mario Radschun, Annette Jobst, Jörg Himmel, Olfa Kanoun

Page range: 332-342

Abstract

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.

February 20, 2020

Analysis of elastic rolling stand deformation and interstand tension effects on section faults of hot rolled wire rod and bars

Christian Overhagen, Rolf Braun, Rüdiger Deike

Page range: 343-348

Abstract

The present work aims at the modelling and simulation of the hot rolling process for wire rod and bars. After the fundamentals of plasticity, which are essential for the understanding of the process characteristics have been described, typical section deviations that can be expected in wire rod and bar mills are calculated with help of a numerical simulation model. The model allows the calculation of section shapes under the influence of elastic rolling stand deformations and interstand tensions. From this computational assessment of section faults, the necessity of inline measurement and process control for wire rod and bar mills is shown. This work is part of the PIREF project which incorporates the development of sensors, control systems and process models in order to control the dimensional accuracy of hot rolled wire rod and bars. The metal forming process model, as described here is used internally as a model for the static and kinematic interactions in the rolling process inside of the control model.

December 18, 2019

A compact and powerful EMAT design for contactless detection of inhomogeneities inside the liquid volume of metallic tanks

Kai Rieger, Daniel Erni, Dirk Rueter

Page range: 349-359

Abstract

A simple and powerful design of an electromagnetic acoustic transducer (EMAT) without bulky permanent magnets is presented. The EMAT is operated in a pulse echo modality and generates longitudinal ultrasound at about 1 MHz. Unlike shear waves, these longitudinal ultrasound pulses can propagate in liquids. The generally addressed application scenario is the examination of a liquid volume inside a metallic container or tank, e. g., the detection of inhomogeneities within the liquid. The herein proposed EMAT operates for virtually all metallic containers, i. e., it succeeds for container walls made of aluminum or ferromagnetic steel, and even for non-ferromagnetic (stainless) steel. Moreover, unlike piezo transducers, EMAT techniques allow for a non-contacting ultrasound transduction: the air gap between the EMAT sensor coil and the tank’s metallic surface extends up to 2 mm. Even with this relatively large air gap, the biasing magnetic field approaches a flux density of 3.2 T at the surface, more than what is possible to achieve with the permanent magnets of conventional and bulkier EMATs. Strong fields improve the coupling efficiency of the principally low-efficiency EMAT mechanism, which is important for both ultrasound transmission and reception. For that superior field intensity, a unipolar current pulse of up to 3.6 kA is applied through the thin windings (0.5 mm) of the EMAT coil. This paper presents a novel solid-state EMAT circuitry for such strong currents and MHz pulsed voltages >1 kV. As a particularly delicate task, the powerful circuitry must also detect the rather weak echo signals in the μV range. A very short recovery time is required after such a strong emission burst. The discussed circuitry consists of three unipolar high-current modules, which can each be independently launched. This allows for received echo signals that can be timed independently, e. g., objects deep inside the liquid tank can be specifically addressed. In general, this work concentrates on the novel circuitry in parallel connection, the general pulse-echo functionality and the magnetic fields. A detailed analysis and shaping of the ultrasonic fields through different EMAT coil geometries would exceed the scope of this contribution and is to be reported separately.

April 11, 2020

Real time executable model for dynamic heat flow analysis of a solar hydrogen reactor

Steffen Menz, Jörg Lampe, Uwe Tröltzsch, Philipp Weiler, Arne Pahl, Thomas Fend, Thomas Seeger

Page range: 360-371

Abstract

A real time executable model developed for dynamic heat analysis of a solar hydrogen reactor is described and characterized. To calculate the local distribution of radiation caused by multiple reflection inside the solar receiver the radiosity method is used. Significant optical characteristics including reflectance, transmittance and absorption are investigated related to the used materials and operating conditions. Furthermore, the influence on the model behavior is presented by variation of optical parameters. Simulation results are presented, which show good agreement with experimental data.

March 28, 2020

Investigation of complex permittivity spectra of foundry sands

Luca Bifano, Alice Fischerauer, Gerhard Fischerauer

Page range: 372-380

Abstract

This paper discusses impedance spectroscopy as a method to characterize different types of quartz sand, chromite sand, and mixtures of sand. Based on two types of measurement cells, the impedance spectra for various dry sands were measured. The spectra differ enough to allow the sands to be distinguished. The results were validated by extracting the relative permittivity from the impedance and comparing it to literature data. After that, the method could be applied with confidence to other material systems. The influence of moisture was investigated with two types of quartz sand, and typical mixtures of form sand, chromite sand, and regenerated (quartz) sand were studied. In each case, the sand composition had a distinct influence on the Nyquist plot of the impedance spectrum. Compared to results from a laboratory foundry system, the new method exhibits a much more systematic dependence on the sand composition. If one succeeds in describing the impedance spectra with an equivalent circuit model parameterized by only a few parameters, these parameters could be used to identify and classify sand mixtures in the field. This would allow one, for example, to implement feedback control strategies in foundry regeneration processes, which would stabilize the processes and improve the quality of the casting products.

About this journal

Objective

The journal promotes dialogue between the developers of application-oriented sensors, measurement systems, and measurement methods and the manufacturers and measurement technologists who use them.

Topics

The manufacture and characteristics of new sensors for measurement technology in the industrial sector
New measurement methods
Hardware and software based processing and analysis of measurement signals to obtain measurement values
The outcomes of employing new measurement systems and methods