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Item type:Publication, Access status: with files , A comparison of the toxicity and asphyxiation risk during bunkering of LH2, LNG and NH3 by means of a quantitative risk assessmentTo achieve the greenhouse gas (GHG) reduction goals set by the International Maritime Organization (IMO), hydrogen, natural gas and ammonia are considered as marine fuel in their liquefied form. Nevertheless, concerns regarding their safety have been raised. Thus, the overarching aim of this investigation is it to addresses these concerns by conducting a comparative analysis of the safety of bunkering these fuels, with a particular focus on toxicity and asphyxiation hazards. A quantitative risk assessment is thus conducted in two steps: first, to identify the probability through a frequency analysis and second, to identify the severity through a consequence analysis. The present study will utilize the requisite safety distance as the threshold for the severity. The calculation of the safety distance necessary for the different fuels is performed utilizing a Gaussian dispersion model. Subsequently, both the necessary safety distance and the frequency of harmful events of all three fuels are then compared. The findings indicate that the frequencies of the toxicity/asphyxiation case are of comparable order magnitude for all fuels. However, the safety distance of ammonia is one order of magnitude larger than that of the other fuels.Publicationtype: Journal Article11 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Single sided water absorption in thick GFRP structures: Mechanical effects and diffusion monitoring by integrated smart sensors(IOP Publishing, 2025); ; ; ; In many application scenarios, such as the wind energy industry, fibre-reinforced polymers undergo atmospheric ageing due to prevailing environmental conditions. As a result, moisture gradients are often present in the material, which influence the material behaviour and mechanical properties. Reliable determination of the current moisture condition at various points in the component and knowledge of the effects of moisture on the mechanical behaviour of the structure can extend the service life and prevent failure. Consequently, this work presents a method for monitoring local moisture absorption and moisture-induced damage in thick GFRP laminates. Therefore, an integrated sensor system based on single carbon fibre (CF) rovings and impedance measurements was developed. Water absorption leads to a change in the dielectric properties of the GFRP, resulting in a significant increase in the phase angle and a simultaneous decrease in the amplitude of the electrical impedance, especially when local fibre-matrix debonding occurs. In addition, the mechanical effects of non-symmetric water absorption are evaluated using four-point bending and interlaminar shear strength tests. The mechanical performance of the aged laminates decreased significantly, even though the water infiltrated the laminates by less than 25 % of the thickness.Publicationtype: Conference Paper89 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Environmental and chemical ageing of epoxy resins cured with bio-based amino acidsTo achieve efficient and sustainable use of raw materials and energy, structures made of lightweight composites and thermosetting polymers are widely used. For sustainability, it is especially mandatory to extend the operating life of structures and components even under harsh conditions. Recently, the transformation from petrochemical to biobased resources is ongoing, to further improve sustainability. However, because of the more polar state of many biobased raw materials, it should be ensured, that they are not lacking in long-term use. In this study, specifically, the evolution of absorption and thermo-mechanical properties such as tensile strength or glass transition temperature (Tg) are analysed after ageing in demineralised water and chemicals (acetone, isopropanol, hydraulic oil) for L-arginine-cured epoxy compared to fully petro-based epoxies. The changes in properties due to physical ageing (molecular relaxation) and diffusion reveal a complex interplay between plasticization, physical ageing and possible chemical degradation. In particular, water absorption promotes strength-reducing plasticization and strength-increasing molecular relaxation on different time scales. This complex interplay is found for both types of epoxies and is in good agreement with what was previously found for classical epoxy. At the same time, the plasticizing effect of water also significantly reduces the Tg, as the water ingress into the molecular structure which increases chain distances and facilitates molecular movements. Furthermore, the resistance of the arginine-cured epoxy against different chemicals is particularly high and the diffusion retarded. Evidence for chemical degradation due to acetone diffusion is detected for both epoxy types via FTIR-analysis.Publicationtype: Conference Paper113 16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Comparative summary of approaches used with the impulse response method(IOP Publishing, 2023-08); ; ; This paper presents a comparison of various methodologies to calculate the seakeeping behaviour of ships using the impulse response method. Developments of several authors incorporate non-linearities regarding the radiation, diffraction and wave forces. In contrast to frequency domain methods, advantages are expected if ship motions become non-linear, for example in waves with high steepness ratios. The comparison is structured into analysis for each force component with and without motions in waves. The main contribution is the quantitative analysis for several ships, forward speeds and methodologies. Multiple frequency domain methods are incorporated in the analysis. The focus of the analysis lies on the evaluation of applicability as well as the limits of the method for all states investigated. The results of the impulse response method show the following: The method is applicable to several forward speeds. In long waves, the choice of the parameters calculated in the frequency domain for the computation of the radiation and diffraction forces has a strong influence on the computed motion amplitudes. In short waves, the computation of the added resistance is a considerable challenge. Especially at high forward speeds, the consideration of the stationary wave system is essential for obtaining accurate results with three-dimensional panel codes.Publicationtype: Conference Paper43 40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimization of a coupled launching process considering hydrodynamic interaction effects(IOP Publishing, 2023-08-01); ; ; Crane-assisted launching and recovering of small boats from a large vessel is common in a wide range of operational scenarios and may be required during research missions or in emergency situations for rescue boats. As the mothership moves in natural irregular seas, the resulting accelerations and motions of the small boat can lead to dangerous situations, such as a collision between the mothership and the small boat or a slamming of the small boat onto the free water surface can occur, posing a great danger to the people involved. In the paper, the development of a coupled simulation method for the motions of the mothership and the small boat during the launching in the time-domain is described. The developed simulation method is based on the impulse response function. The implementation of the suspension on a crane is realised by a holonomic constraint and a Lagrange’s equation. The parameter influencing the launching operation include the current sea state, the stationary wave field induced by the motherships forward speed, at which the small boat is launched and the initial position of the small boat relative to the water surface. By varying the above mentioned parameters, the process can be optimised for different sea states in terms of forces and accelerations. In considering the forward speed of the mother boat during the launching process, it can be observed that in many cases the small boat is operated at high Froude numbers of greater than 0.4. This leads to an exceedance of the operational limits of the programmes used in this paper.Publicationtype: Conference Paper15 11 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , An information-theoretic perspective on acting agentsEvery embodied intelligent agent constantly interacts in its own way with its environment. It perceives information about the world, processes this information in its controller, e.g. its brain, and sends signals to the body, which then interacts with its surroundings. Here we give a thorough introduction to an information-theoretic approach that aims at quantifying these information flows among an agent's body, brain and environment. Thereby we measure how much an information flow impacts the behavior of an agent. For instance, we might ask the question whether the brain is essential for a certain behavior or whether it is a reflexive stimuli response. In order to measure these interactions we model the system using the sensorimotor loop and assess the different information flows by information-theoretic measures. This includes measures related to Morphological Computation and the complexity of the controller. Morphological Computation describes the reduction of computational cost for the controller that results from the interaction with the environment. We include results from an implementation of this framework with simplistic simulated robots. Experiments with these robots show, for instance, that an agent with a well-adapted body does not rely as much on its controller. Furthermore, learning a new task requires an increased information integration in the controller.Publicationtype: Conference Paper17 44 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , The determination of the disc brake thermal stresses for different vehicle speeds(IOP Publishing, 2022); ; ; ; From the aspect of traffic safety, the brake system is one of the most important systems. For all exploitation conditions, for which vehicles are projected, and for loads in prescribed boundaries, no matter to the vehicle speed, it is important, for the brake system to be reliable and to provide a very fast stop, or speed adjustment to road conditions. During the stop or during the speed adjustment it comes to the disc brakes temperature increment. So, because of this, the experimental investigations were conducted, in order to determine final values of the temperature for multiple braking processes until stop. In this paper, were conducted two experimental tests for the same vehicle, but for different speeds, which were 60 km/h and 80 km/h, while the other parameters (initial temperature, the mass of the simulated vehicle, number of repetitions) were the same for both tests. The conclusion is that by increment of the speed, rises the necessary time to stop the simulated vehicle, and by this, rises and the stopping distance. Also, rises and the temperature of the disc brake, with the increment of the vehicle speed.Publicationtype: Journal Article72 119 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Reduction of the environmental impact of aviation via optimisation of aircraft size/range and flight networkAbstractREIVON is a Clean Sky 2 Technology Evaluator project that investigates to what extent CO2 emissions of global aviation can be reduced via optimisation of aircraft size/range and flight network. Three alternative global flight networks are created, considering (1) splitting long-haul flights into shorter legs (intermediate stop operations, ISO), (2) reducing frequency to the necessary minimum on busy routes using larger aircraft, and (3) a combination of 1 and 2. In all cases, the use of aircraft optimised for specific combinations of range and seating capacity not existing today will be considered. For the first time, REIVON will carry out a holistic analysis of the impact of an optimised flight network on global air transport system stakeholders, such as passengers, aircraft manufacturers, airlines and airports, and of potential measures to support the implementation of such an alternative network.Publicationtype: Journal Article81 161 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Towards an investigation of a MASS-assisted anti-grounding service through simulated nautical scenarios in a ship handling simulator(IOP Publishing, 2020-11); ; 24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , From Sensors to MASS: Digital Representation of the Perceived Environment enabling Ship Navigation(IOP Publishing, 2020-11); ; ; Maritime Autonomous Surface Ships (MASS) do require shifting from human information processing to automation functions. While supporting the sensory processing of human navigation by automated information acquisition from different sensors is an already established (and even in many cases mandatory) technology with a set of framing standards and information exchanges, defining a common data set for a perceived environment model is currently neglected which hinders modularization of MASS technology development. Beginning with an introduction into the navigational process as well as information processing, this paper subsequently proposes an initial minimum data set for different aspects of ship navigation.Publicationtype: Conference Paper22