•The recent morpho-stratigraphic setting of the GMS is reconstructed.•Turbidity currents interact with a complex morphology.•Erosive-depositional features are mostly related to overflow processes.
...The collection of high-resolution multibeam bathymetry, single-channel seismic profiles, TOBI side scan sonar data, and gravity cores allowed the characterization of the main morpho-sedimentary processes acting along the lower reach of the shelf-indenting Gioia-Mesima canyon-channel system (GMS) and the surrounding continental slope (southern Tyrrhenian Sea). This last area, developing across a depth range of 1000–1700 m, shows a complex morphology due to the interaction between downslope gravitative processes (mainly turbidite sheet flows) and abrupt changes in slope gradients related to tectonically-controlled scarps. Particularly, several erosive-depositional features (levee deposits, sediment undulations, channels) have been related to overflow processes from the northern flank of the GMS, although the lower reach of the GMS is characterized by strong entrenchment (canyon height ranging from 120 to 270 m) and low sinuosity. Morphological and seismic stratigraphy data indicate that the distribution and dimension of these features vary in response both to the proximity to the external levee of the GMS and to the topographic gradient of the lower continental slope. Particularly, we were able to discriminate between a gently sloping sector (on average 1.5°) dominated by sedimentary bypass of the turbidity currents and a steeper sector (about 3°), where the erosional capability of these currents seems to increase. Indeed, three channels, 4,3–6,5 km long and up to 20 m deep, incise this steeper sector, running parallel to each other at a distance of 1250–1500 m. To support the capability of overbanking flow in producing these channels, we used a physical model for the ignition of turbidity currents that provides realistic values for the ignitive state of the overbanking turbidity flows. More generally, the methodological approach used in this study may be useful to provide constraints on the genesis and evolution of erosive-depositional features in other tectonically-controlled margins, where sedimentary gravity flows interact with an uneven morphology.
•Diel Vertical Migration (DVM) affects sea lice horizontal transport and retention.•In fjordic systems, lice DVM can interact with the estuarine circulation.•Asymmetry between up/down-ward lice ...velocity influences their vertical distribution.•Quick sea lice upward velocity leads to less retention within the fjord.•Sea lice management can be enhanced when models include accurate DVM.
Sea lice are ectoparasites that can be found in high numbers in and around salmon farms, where they are a threat to fish health and can induce high aquacultural costs. Large numbers of suitable hosts facilitate the infection and subsequent release of their planktonic larvae in the surrounding environment where they can potentially infect wild salmonids, including migrating juvenile fish (smolts). Investigating sea lice spatial distribution is generally done using coupled hydrodynamic and particle tracking models. The quality of these numerical tools is critical to identify areas of higher infection risk to valuable wild salmon populations and thus support sustainable salmon aquaculture. While the transport of salmon lice is mainly affected by physical processes, biological behaviours such as vertical swimming can also play an important role. However, a review of previous sea lice studies shows no clear consensus on their swimming abilities and the parameters implemented in sea lice dispersion modelling. Here, we focus on the Diel Vertical Migration (DVM) behaviour, a vertical migration that sea lice perform within a daily cycle. Our sensitivity study of the infectious copepodid phase of sea lice highlights how their retention potential and spatial distribution within a water body are affected by their vertical swimming velocity and maximum swimming depth. In a fjordic system (Loch Linnhe on the West Coast of Scotland), the vertical position of sea lice can affect their horizontal trajectory due to the two-layer exchange flow of the estuarine circulation. At the surface, transport is mainly due to the wind driven circulation, and the residual seaward current. Lower in the water column, the saltier shelf water is drawn into the sea loch. This can potentially increase the retention of sea lice if they dive deep enough to reach those opposing subtidal currents. Therefore, lack of confidence in sea lice DVM parameterisation may introduce inaccuracy in modelled sea lice distribution. Effective sea lice management in aquaculture would benefit from more observational data like farm sea lice count, sea lice swimming laboratory observations, field observation of sea lice vertical distribution and accurate sea lice quantification in the field. This would help to reduce uncertainties derived from sea lice vertical swimming behaviour parameterisation in lice dispersal models.
The maintenance of railway infrastructure plays a critical role in ensuring the optimal availability and safe operation of railway tracks and associated equipment. Nevertheless, the preservation of ...train power transmission lines presents noteworthy hazards as a result of the amalgamation of electrical perils and maintenance-associated risks. This study aims to present the design and simulation of a planar translational scissor lift mechanism. The objective is to assist maintenance personnel in the rail sector specifically during power transmission line maintenance. The scissor-lifting mechanism was modelled in Solid Works, a software programme known for its comprehensive 3-D modelling capabilities. Additionally, a mathematical model was constructed to analyse the behaviour of the scissor lift. The dynamic response of the system was investigated through the utilisation of MATLAB/Simulink to conduct kinematic and kinetic simulations. The research findings unveiled the comparative kinetic correlation between the hydraulic cylinder and other constituent elements, effectively capturing their dynamic behaviours throughout the operational process. In addition, the utilisation of Simscape facilitated the optimisation of the mechanism's design through simulation analysis, thereby offering valuable insights to inform and improve subsequent design iterations. The experimental findings indicate that the system design effectively raised the maintenance platform to a height of 2 metres in a time of 20 seconds while accommodating a load range of 500 to 1000 kg. The study presents a systematic and logical design approach that establishes a scientific foundation for the mechanism. This positions it as a valuable theoretical reference for future advancements in scissor lift development. The results of this study make a valuable contribution towards enhancing safety and efficiency in rail maintenance operations. Additionally, they help in reducing the risks associated with power transmission line servicing. Furthermore, these findings lay the foundation for future advancements in railway maintenance technology.
In this contribution, a holistic energy flow analysis of a solar driven pilot plant for green hydrogen production using two-step thermochemical cerium-based redox cycles is carried out. The plant ...consists of a heliostat field, a large-scale inert gas reactor, an efficient fluid heat recovery system and an electrical vaporizer for steam generation. The system behaviour is physically described, and energy flows are quantified using a complex simulation model considering material and geometric properties of the complete system design. The system energy flow and corresponding impact on plant efficiency is thoroughly analysed with emphasis on plant design, operational strategy, and influence of the crucial control parameters. Influences of a heat recovery system and the size of various types of heat losses are investigated, potential efficiency improvements are revealed and useful possibilities for plant design and material modifications are discussed. The transient system behaviour is investigated by varying temperatures and mass flow rates in a broad practicable range to gain more insight in efficient reactor design and plant control. Two temperature swing strategies are investigated in more detail, which are by far more efficient than any near-isothermal or isothermal strategy for this application.
Ti-17 is exposed to microstructural modifications during thermomechanical treatment. In this work, we focus on the characterisation, analysis and modelling of the modifications during plastic ...deformation in the one phase and two phases domain. Hot compression tests are carried out between 810 °C and 970 °C and at 0.001 s−1 to 10 s−1 up to 0.85 strain. Metallographic observations and quantifications are done using SEM-EBSD. A physically-based model is developed to describe the deformation mechanisms: dynamic recovery, followed by continuous dynamic recrystallisation, and dynamic globularization of the α-phase. Flow stresses, dislocation densities, and sizes of both phases are predicted as a function of strain rate and temperature for different starting microstructures. The thickness and aspect ratio of the α-phase is predicted as well as the globularization fraction. The flow softening in the α + β domain is attributed to a change in the load transfer mechanism between α and β-phases from isostrain to isostress due to the dynamic globularization of the α-phase. High strain rates promote the formation of finer subgrains of β and less globularization of α-phase. Moreover, cDRX starts at larger strains in the β-domain and is more advanced already at moderate strains for the deformation in the α + β domain.
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•Comprehensive rate equations for dislocation reactions are coupled to a physical model for dynamic α-globularization.•A change in the load partitioning between α and β-phases leads to flow softening.•The presence of the α-phase accelerates the continuous dynamic recrystallization of β-phase.•The developed physical model can predict the evolution of any starting microstructure.
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•Additive manufacturing is used to physically model Reinforced Concrete at a 1:30 scale.•Submillimeter diameter rebars of suitable mechanical and bond behavior are used.•Tuning of ...printing parameters, bar surface roughness and concrete mix is needed to maintain similitude.•Additional surface ribs should be printed with the bars to simulate prototype bond behavior.•Gypsum-based mixes are more similar to prototype concrete than cement-based mixes.
Small scale (∼1:30–1:40) Reinforced Concrete is useful for centrifuge testing. However, manufacturing the reinforcing cages by hand at this scale is practically difficult. This paper suggests that small scale reinforcement can be manufactured using a metal 3D printer. Mechanical properties of 3D printed submillimeter rebars are discussed and compared to properties of typical prototype rebars. Different model concrete mix designs are tested to identify optimal mixes. Pullout tests of rebars with different surface rib configurations embedded in different concrete mixes are discussed.
Based on the test results, by modulating the printing parameters it seems feasible to obtain 3D printed submillimeter bars that can be used as physical models of prototype rebars. A gypsum-based model concrete was more similar to prototype concrete than cement-based mixes. Most importantly, bond slip behavior that is comparable to full-scale concrete could be achieved, something that is vital and has never been reported before.
•A hybrid wind-wave energy converter for monopile substructures is developed.•A thorough experimental campaign is carried out using a 1:40 model.•The interaction of the hybrid energy converter with ...the wave field is characterised.•The influence of turbine damping and wave conditions on performance is assessed.
Multipurpose platforms are innovative solutions to combine the sustainable exploitation of multiple marine resources. Among them, hybrid wind-wave systems stand out due to the multiple synergies between these two forms of marine renewable energy. The objective of this work is to develop a hybrid system for monopile substructures, which are currently the prevailing type of substructure for offshore wind turbines, and more specifically to focus on the wave energy converter sub-system, which consists in an oscillating water column. For this purpose, an in-depth experimental campaign was carried out using a 1:40 scale model of the wave energy converter sub-system and the monopile substructure, considering regular and irregular waves. Based on the experimental results the performance of the device and its interaction with the wave field were characterised – a fundamental step to fully understand the benefits and limitations of this hybrid wind-wave system, which sets the basis for its future development. Regarding the performance, the best efficiency was obtained with the turbine damping corresponding to a 0.5% orifice size, and two resonance peaks were identified (T = 9 and 6 s). As for the interaction of the hybrid system with the wave field, between 5% and 66% of the incident wave power is reflected and between 3% and 45%, transmitted. The wave period was found to be the parameter that most influenced wave run-up on the substructure. This characterisation of the behaviour of the hybrid system shows that it is indeed a promising option for further development.
In this work, a novel structure of a Quadrotor Unmanned Aerial Vehicle (UAV) is proposed to change the dynamics during flight. The proposed mechanism is presented which consists of extendable plates ...that move along the horizontal axes from the body frame respectively. Essentially, the main goal behind this novel architecture is to enhance performance and improve flight duration in reaching the desired position. The Euler dynamic model is derived to represent the multirotor equation of motion. Basic PID controllers were implemented to demonstrate the concept and to analyse the vehicle behaviour as the structure is altered during flight. A physical modelling software is also used to study the multi-body interactions of rigid bodies as well as the dynamic response. By comparing the performance between the proposed system and the traditional version, the paper reveals improved flight performance for attitude and position tracking. The mathematical representation of the dynamic system was also verified using Msc ADAMS as identical control inputs where simultaneously applied.
A statistical physics modelling analysis was performed to explain the adsorption of methylene blue (MB) dye on both nano-silica (RNS) and microwave modified nano–silica (MMNS) in the temperature ...range of 25–55 °C. Interestingly, it was demonstrated that the MB dye adsorption occurred via the formation of two layers on surfaces of both RNS and MMNS. The number of linked adsorbate (MB dye) molecules per functional groups varied from 0.59 to 1.0 for MB-RNS and from 0.64 to 1.112 for MB-MMNS, respectively. Based on these calculations, the adsorption orientation of MB molecules on these adsorbents was estimated to be a mixed orientation (parallel and non parallel) at tested temperatures. Overall, the occupied density of functional groups (Dm) at saturation was the parameter controlling the variation of the adsorption capacity. Calculated energies of MB dye adsorption mechanism indicated an exothermic process where physical forces were involved. These adsorbents showed a competitive performance compared to other materials used in dye removal.
•Adsorption of methylene blue over silica studied via statistical physics model•Nanosilica and microwave heating nanosilica materials involved•Steric and energetic evidences were developed.•Coexistence of horizontal and inclined adsorption configurations
Perforated multichamber caisson breakwaters are widely used for deep water harbour protection from waves, causing a partial dissipation of wave energy, hence reducing wave reflection. The innovative ...patented geometry presented in this paper, the ARPEC, is an Anti Reflection PErmeable Caisson breakwater that allows a significant wave energy dissipation and a hydraulic connection between the sea side and the port side by means of a labyrinthine pattern of offset openings in all external and internal walls. The hydraulic response of this innovative structure is evaluated by means of both 2D physical and numerical models. It is shown that, when compared with traditional impermeable perforated caissons, the marginal increase of wave transmission (CT=HT/HI in the approximate range of 0.1–0.2, varying with wave period) is compensated by a slight reduction of wave reflection (CR=HR/HI in the approximate range of 0.3–0.6, varying with wave period) and by an enhanced water circulation in the sheltered basin, which is beneficial for flushing of microtidal harbours.
•Novel geometry concept of perforated caisson, ARPEC, Anti Reflection PErmeable Caisson.•2D Physical model tests on hydraulic performance of the ARPEC with length scale 35.55 in Froude Similarities.•2D numerical model tests with OpenFOAM Software. The accordance between the numerical and physical models is evaluated by means of cross validation with the determination coefficient R2 that varies from 0.87 (for incident wave height) to 1 (for wave period) as evidence of a very good accordance between the numerical and physical models.•Reflection (CR) and transmission (CT) coefficients analysis has been performed under regular and random wave action, obtaining, for random waves CR values in the range 0.28–0.58 and CT between 0.13 and 0.22.•Water flushing analysis by imposing initial sea-level gradient between the sea and port sides of the caisson.
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