Risk assessment of war wrecks – a comprehensive approach investigating four wrecks containing munitions in the German Bight/North Sea

Shipwrecks and dumped munition continue to be a major hazard, both in the North Sea but also on a global scale. Research within the EU Interreg project North Sea Wrecks (NSW), in cooperation with the German Aerospace Centre, Institute for the Protection of Maritime Infrastructures (DLR), is generating new insights into the status of wrecks, the potential leakage of pollutants from remaining munitions loads and the effects of contamination on exposed marine organisms in the North Sea environment. Further, historical documents are generated from archives to describe ship’s history and sinking scenario. These historical findings were compared to models and images of the visual inspections of the wrecks. Further, samples of water, sediment and organisms are being analysed for traces of explosives. Combining the results of these different fields of research allows for a better understanding of the environmental risks deriving from these wrecks. This process is shown below by focusing on the wreck of the German light cruiser SMS MAINZ, which sank in 1914. Data were compared to three additional wrecks situated also within the southern German Bight. Available data about the wrecks were preliminary assessed using a wreck risk model. Finally, wrecks were ranked according to their potential environmental risk

North Sea Wrecks - An interdisciplinary approach towards understanding the risks posed by wrecks containing munitions in the North Sea

Shipwrecks and dumped munitions continue to be a major hazard in the North Sea. Research within the EU Interreg project North Sea Wrecks (NSW), in cooperation with DLR, is generating new insights into the status of wrecks, the potential leakage of pollutants from munitions loads and the effects of contamination on exposed marine organisms in the North Sea environment. Further, historical documents are compared to models and visual inspections of the wreck. Samples of water, sediment and organisms are being analysed. Combining the results of these different fields of research allows for a better understanding of the environmental risks deriving from these wrecks. The extended article will detail the wreck of the SMS Mainz as a case study

Entwicklung und experimentelle Validierung einer Marssimulationsanlage für astrobiologische Experimente

The requirements of the diploma thesis consisted in building an experimentation chamber capable of producing Mars-like environmental conditions. The main focus resided in simulating the composition of the atmosphere, as well as its pressure, temperature and humidity. On the basis of this data, a regulating device was designed in order to measure and directly influence the environmental parameters. The aim of the thesis was to build a chamber which could later accommodate sample bowls with micro-organisms. Based on the products of their metabolism, one should be able to deduct whether or not micro- organisms can survive and metabolise under such extreme conditions. The main element of the Mars simulation chamber is a high-vacuum chamber, capable of accommodating the samples, and which can be evacuated via two vacuum pumps. A vacuum measurement device gauges the low pressure within the chamber and displays the results on the dials. A humidity sensor, capable of resisting vacuum conditions, registers the humidity within the chamber whereas PT-100 resistance thermometers show the temperature. Additionally, all measurement devices are connected to a data reception card that forwards them to a controlling processor. The control software, programmed in Labview, displays the received parameters on the screen and takes over the whole pressure regulation. With the help of this control software, cyclical pressure fluctuations, consistent with those on Mars, can be programmed as well. The regulation is carried out by two electromagnetic vacuum valves that are also connected to the NI-card. The desired amount of water is introduced manually into the atmosphere using a reservoir that leads water into the system and which can be closed by a hand valve once the designated water concentration has been achieved. The temperature regulation in the Mars chamber is controlled with a programmable external cryostat, attached to a copper spiral inside the chamber that reliably forwards the appointed temperature to the experimentation chamber

Messung von Diffusionskoeffizienten in hochschmelzenden, metallischen Flüssigkeiten mit Scherzellentechnik8

The determination of inter- and self-diffusion coefficients of refractory sample systems requires the usage of a new type of crucible materials, measuring installations and -methods. For the measurements within the scope of this work, the shear-cell method was combined with an isothermal furnace, which was also developed for the use in weightlessness. The shear-cell furnace built by the company Astrium (Airbus) and the Technical University of Freiberg was used in order to establish its characteristics regarding function and temperature distribution as well as for the measurement of the diffusion coefficient. In order to achieve this, a series of changes regarding its overall structure had to be implemented. During the calibration measurements, temperatures of 1500°C within the shear-cell could repeatedly be achieved. The isothermal area along the sample was of 90 mm; the temperature gradient along the heating zone was a maximum of 2 K. The furnace itself can be heated up to temperatures of 1650°C. The heating parameters for 5 different diffusion temperatures were determined in order to guarantee an isothermal area of ±1K along the capillaries. This was necessary in order to compensate heat loss along the shear cell and in preparation for each diffusion test series with the graphite shear cell. This experiment differs from other already existing shear-cells due to the high amount of measuring points, the length and the amount of samples as well as the extreme temperature stability of the experiment buildup. Because the construction can be tilted, the melting column can be aligned with gravitational acceleration, which favours the creation of a stable density layer within the melting pillar. The fusing of the samples in a horizontal position avoids segregation effects. The isothermal area minimizes the transport of material within the melt due to convection. Pre-stressed repositories are balancing volume expansion or shrinkage of the samples. This ensures a complete filling of the capillaries and prevents free surfaces on the capillary walls or the formation of bubbles within the melt. The shear processes at the beginning and at the end of the diffusion process allow a precise determination of the soak time and prevent the influence of solidification phenomena on the concentration profile. In this work, the inter-diffusion and self-diffusion coefficients were measured on Al-Cu. To achieve this, several shear cell experiments were conducted under identical process conditions and with varying concentration gradients around the average concentration of Al$_{87,5}$Cu$_{12,5}$ in the graphite shear-cell. CT analysis and the determination of concentration profiles with AAS were used for the evaluation of the results. The analysis with different measurement techniques reduces the amount of errors. The newly determined inter-diffusion coefficients differ from previously published results. The analysis of the concentration profiles were performed with x-ray tomography and chemical AAS analysis. The calculated self-diffusion and inter-diffusion coefficients match the assumed 10% measurement error. The minor deviations of the measured results when using two different measuring processes over a high amount of experiments prove the reliability and the precision of the shear cell method that was used in this work. In the context of another dissertation at the Institute of Materials Physics in Space, shear- cell experiments to measure the inter-diffusion on the system AgCu and the ternary AlCuAg alloy were carried out parallel to this work. Because of the high isothermal area and the increased amount of sample segments that could be analysed, the shear cell method presented in this work represents an adequate measurement method for sample systems with limited x-ray contrast. To date, the mutual influence of the alloying components as well as the correct choice of evaluation methods render the collection of precise measurement results on ternary sample systems rather difficult. Four shear-cell measurements around the area of the AlCuAg-eutectic were carried out to complete and verify the results obtained. Despite the lack of process observations, it is clear that the shear-cell, in combination with an isothermal furnace, provides reproducible results on ternary alloys, which also correlate with the results of neutron radiography, within the limit of tolerance regarding measurement and analysis/evaluation errors. Alongside the measurements described on the Al-Cu, Ag-Cu and AlCuAg systems, shear-cell experiments to determine the inter-diffusion coefficient on varying Al-Ni systems were also carried within the scope of this work. Part of this work focuses on the analyses of chemical compatibility between potential crucible materials for the production of a high temperature shear cell and high-melting Al-Ni melts. The analyses resulted in the production of a shear-cell made of BN, with 35% ZrO$_2$, which combines the characteristics of the graphite cell with the chemical stability of BN. The first shear cell experiments include measurements around Al$_{71,02}$Ni$_{28,98}$. In an additional experiment, measurements to determine the inter-diffusion coefficient were also carried out on Al$_{25}$Ni$_{75}$. With this boron nitride cell, it was possible for the very first time to perform inter-diffusion shear cell experiments on high-melting Al-Ni at process temperatures above 1400°C for the very first time

Messung von Diffusionskoeffizienten in hochschmelzenden, metallischen Flüssigkeiten mit Scherzellentechnik8

The determination of inter- and self-diffusion coefficients of refractory sample systems requires the usage of a new type of crucible materials, measuring installations and -methods. For the measurements within the scope of this work, the shear-cell method was combined with an isothermal furnace, which was also developed for the use in weightlessness. The shear-cell furnace built by the company Astrium (Airbus) and the Technical University of Freiberg was used in order to establish its characteristics regarding function and temperature distribution as well as for the measurement of the diffusion coefficient. In order to achieve this, a series of changes regarding its overall structure had to be implemented. During the calibration measurements, temperatures of 1500°C within the shear-cell could repeatedly be achieved. The isothermal area along the sample was of 90 mm; the temperature gradient along the heating zone was a maximum of 2 K. The furnace itself can be heated up to temperatures of 1650°C. The heating parameters for 5 different diffusion temperatures were determined in order to guarantee an isothermal area of ±1K along the capillaries. This was necessary in order to compensate heat loss along the shear cell and in preparation for each diffusion test series with the graphite shear cell. This experiment differs from other already existing shear-cells due to the high amount of measuring points, the length and the amount of samples as well as the extreme temperature stability of the experiment buildup. Because the construction can be tilted, the melting column can be aligned with gravitational acceleration, which favours the creation of a stable density layer within the melting pillar. The fusing of the samples in a horizontal position avoids segregation effects. The isothermal area minimizes the transport of material within the melt due to convection. Pre-stressed repositories are balancing volume expansion or shrinkage of the samples. This ensures a complete filling of the capillaries and prevents free surfaces on the capillary walls or the formation of bubbles within the melt. The shear processes at the beginning and at the end of the diffusion process allow a precise determination of the soak time and prevent the influence of solidification phenomena on the concentration profile. In this work, the inter-diffusion and self-diffusion coefficients were measured on Al-Cu. To achieve this, several shear cell experiments were conducted under identical process conditions and with varying concentration gradients around the average concentration of Al$_{87,5}$Cu$_{12,5}$ in the graphite shear-cell. CT analysis and the determination of concentration profiles with AAS were used for the evaluation of the results. The analysis with different measurement techniques reduces the amount of errors. The newly determined inter-diffusion coefficients differ from previously published results. The analysis of the concentration profiles were performed with x-ray tomography and chemical AAS analysis. The calculated self-diffusion and inter-diffusion coefficients match the assumed 10% measurement error. The minor deviations of the measured results when using two different measuring processes over a high amount of experiments prove the reliability and the precision of the shear cell method that was used in this work. In the context of another dissertation at the Institute of Materials Physics in Space, shear- cell experiments to measure the inter-diffusion on the system AgCu and the ternary AlCuAg alloy were carried out parallel to this work. Because of the high isothermal area and the increased amount of sample segments that could be analysed, the shear cell method presented in this work represents an adequate measurement method for sample systems with limited x-ray contrast. To date, the mutual influence of the alloying components as well as the correct choice of evaluation methods render the collection of precise measurement results on ternary sample systems rather difficult. Four shear-cell measurements around the area of the AlCuAg-eutectic were carried out to complete and verify the results obtained. Despite the lack of process observations, it is clear that the shear-cell, in combination with an isothermal furnace, provides reproducible results on ternary alloys, which also correlate with the results of neutron radiography, within the limit of tolerance regarding measurement and analysis/evaluation errors. Alongside the measurements described on the Al-Cu, Ag-Cu and AlCuAg systems, shear-cell experiments to determine the inter-diffusion coefficient on varying Al-Ni systems were also carried within the scope of this work. Part of this work focuses on the analyses of chemical compatibility between potential crucible materials for the production of a high temperature shear cell and high-melting Al-Ni melts. The analyses resulted in the production of a shear-cell made of BN, with 35% ZrO$_2$, which combines the characteristics of the graphite cell with the chemical stability of BN. The first shear cell experiments include measurements around Al$_{71,02}$Ni$_{28,98}$. In an additional experiment, measurements to determine the inter-diffusion coefficient were also carried out on Al$_{25}$Ni$_{75}$. With this boron nitride cell, it was possible for the very first time to perform inter-diffusion shear cell experiments on high-melting Al-Ni at process temperatures above 1400°C for the very first time

Construction and experimental validation of an electromagnetic levitation facility for the measurement of thermophysical properties in liquid metal

The electromagnetic processing without crucibles is a key technology for materials science to study the formation of meta-stable phases and nucleation phenomena and it also allows the measuring of important thermo-physical material properties such as heat capacity, surface tension, thermal conductivity and viscosity of high-melting samples. In Cologne, at the DLR institute for materials science (Materialphysik) in space, methods for processing molten metal without receptacles under reduced gravity have been employed for years to analyse non-equilibrated solidification. During terrestrial levitation experiments, gravity and the magnetic field deform the sample. Therefore, an exact evaluation of the vibrational spectrum of a-spherical samples is only possible if corrections are applied. Micro-gravitation offers the possibility to measure the oscillation of ball-shaped samples because, in opposition to earthbound experiments, the samples are decoupled from the interfering positioning fields. For this kind of experiment the DLR uses the TEMPUS-apparatus. TEMPUS stands for Tiegelfreies Elektromagnetisches Prozessieren unter Schwerelosigkeit (electromagnetic processing without platens at zero gravity) and describes a scientific experimentation apparatus where fused and undercooled metals and alloys are researched. In this apparatus, electronically conducting samples with a diameter between six and ten millimetres can be brought to levitate, heat up and melt in a inductor coil with electric current. Since the samples levitate free from the coil, no container is needed, in opposition to conventional smelting in a furnace. Thus, the molten metal, which can be chemically very reactive at times, does not touch the material of the container. Consequently, the samples are not contaminated and it is even possible to keep the metals liquid below their solidification point. Comparative experiments in space and on earth allow the experiential designation of gravitational phenomena such as convection, sedimentation and uplift, which is a pre-requisite for the development of physical models to quantitatively describe solidification processes. The TEMPUS apparatus is used during parabola flights and a modified version is also employed in TEXUS-altitudinal research missiles. This produces effective processing times at zero gravity between 22 and 300 seconds. In the light of long term research, a modular mechanism is meant to be installed on the ISS (International Space Station) in the European space laboratory COLUMBUS in 2011. When samples are heated significantly above their melting point in a vacuum environment, a considerable amount of the material from the sample surface evaporates and condenses on the neighbouring cold parts of the machine. If the processing takes places in a gas atmosphere, the material flow of the condensed particles is limited due to the diffusion process. The gas flow transports the particles away from the sample and the particles then form dust, which remains in the atmosphere or sticks to surfaces, but does not form a homogenous layer. Condensation from the sample material on the water-cooled copper coil must not cause electronic short-circuits between the various coils. The cumulative effect makes the layer of the condensed sample material thicken to the point that it separates from the coils, or from the walls of the recipient respectively. Material flakes that separate from the coils can cause contamination of the sample or premature consolidation. In order to minimise these dangers, the temperature-dependent condensation rate of each material to be processed has to be determined. Hence, exact temperature and time profiles of the samples to be processed are an indispensable pre-requisite. The primary research aim of the assembled equipment to measure condensation rates (ARMA – Abdampfratenmessanlage) is the detailed analysis of the various condensation rates of material under a vacuum environment and under a protective gas atmosphere within the overall framework of the ground accompanying programme. For this purpose, the vacuum chamber of the experimentation machine has been equipped with a deposition monitor to measure the layer thickness of the condensed material. The amount of condensed material during an experiment can be determined with the help of both, an experimentation plan, and the knowledge of the different condensation rates under in a vacuum environment and 400mbar protective gas atmosphere. As a result, a detailed schedule can be set up. Opening of, or damage to, the experimentation chamber can release toxic concentrations of metal particles into the space platform. A limited amount of condensation and the resulting reduced layer thickness also diminish the processing time of the samples to be analysed. Analyses of the cumulative effect have shown that the overall thickness of the condensed material on the coils should not exceed 20μm to guarantee a stable layering. This limit has been adopted by the ESA as the research requirement. The condensation rate of the individual samples thus defines their possible processing time on the space platform. Ten experimentation containers (batches) with eighteen samples each are scheduled to be on the MSL-EML in a first stage as they can share among themselves the maximum amount of condensed layer thickness. Heavily fuming materials thus have to be processed for a shorter time than less fuming materials in order to adequately divide up this limited resource

MSL compatible isothermal furnace insert for high temperature shear-cell diusion experiments

For long-time diusion experiments shear-cell techniques oer more favourable terms than the traditional long capillary techniques. Here, we present a further developed shear-cell that enables the measurement of diusion coecients up to temperatures of 1600 C. Hence, diusion experiments can be carried out at temperatures not accessible until now by conventional capillary or shear-cell techniques. The modied shear-cell, which can contain up to six samples of a total length of 90mm and a diameter of 1.5 mm, is built of 30 shear discs of 3mm thickness each. It is operated in an isothermal furnace insert which can be accommodated in the Materials Science Laboratory of the International Space Station. This provides the opportunity that the shear-cell can be applied to microgravity and to ground-based experiments, respectively. The heater insert with an overall length of 518mm and a diameter of 210mm consists of four heating zones with a total power of 3.5 kW. Temperature homogeneity along the graphite sample compartment is better than 2K at 1600 C. Details of the new design are discussed and results of rst successfully performed heating and shearing cycles are presente

Drohnengestützte Erfassung von maritimen Infrastrukturen

Das Institut für den Schutz maritimer Infrastrukturen des Deutschen Zentrums für Luft- und Raumfahrt e.V. in Bremerhaven befasst sich mit der Entwicklung von automatisierten Technologien und echtzeitnahen Verarbeitungsmethoden zur Erstellung neuartiger Lagebilder für den maritimen Bereich. Über- und Unterwasser-Drohnen (UAV, AUV, ROV) werden mit neuartigen optischen Kamera- und Sonarsystemen eingesetzt, um dreidimensionale Lagebilddaten aufzunehmen. Spektrale Informationen und dreidimensionale Punktwolken werden zu Lagedarstellungen kombiniert, die die Lösung von Sicherheitsfragestellungen vereinfachen und beschleunigen (Suche von Lecks, Schäden an Anlagen, Erfassung von Fahrzeugen und Personen auf dem Hafengelände). Die Technologie leistet einen wichtigen Beitrag zum Überblick über die maritimen Infrastrukturen. Durch die gute Verfügbarkeit und die Leistungsfähigkeit der Systeme sowie Möglichkeiten zum automatisierten Betrieb lässt sich der zeitliche Aufwand der Modellierung auf ein Minimum reduzieren