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This paper introduced automated detection and analysis of lunar craters are crucial for advancing lunar research and facilitating mission planning. This study introduces a comprehensive multi-scale approach for crater detection on the lunar surface using LROC (Lunar Reconnaissance Orbiter Camera) Dataset, enabling the identification of craters across varying scales and enhancing overall detection accuracy and efficiency. The process involves preprocessing lunar imagery to enhance features and delineate potential crater regions, utilizing edge detection algorithms to extract crater boundaries. Clustering techniques are then applied to group similar edge points and isolate potential crater candidates. A thresholding mechanism based on statistical edge intensity analysis refines the detection process. To address multiple detections of the same crater at slightly different diameters, radius criteria are implemented, yielding high diameter accuracy of 84% for mare Imbrium (test site 1) and 80% for mare Nubium (test site 2). Subsequently, a depth-diameter analysis validates crater-like characteristics by combining depth measurements with crater diameter estimation, showcasing the authenticity of potential craters. we compare our diameter and depth with different reference papers and we get high accuracy of R2 =0.99 then other methods. The results highlight the potential of this multi-scale approach for automated lunar crater detection, providing deeper insights into the Moon's surface morphology and history for future lunar exploration missions. [ABSTRACT FROM AUTHOR]

The empirical approach of satellite-derived bathymetry provides a straightforward, easily-implemented, and very effective way of estimating shallow-water depths from high-spatial-resolution satellite images. However, this approach has a great challenge that it requires high-quality in-situ depth data, which often do not exist or are not available due to financial and/or technical reasons, as the depth calibration data. To address this problem, this article assesses the feasibility of replacing high-quality in-situ depth data with four kinds of possible sourced depth data in satellite-derived empirical bathymetry. These four kinds of depth data are satellite altimeter depth data from laser altimeter systems on some earth observing satellites; satellite photogrammetric depth data, which are derived from satellite stereo-images with the photogrammetric method; nautical chart depth data, which come from existing electronic or paper charts; and radiative transfer model-based depth data, which are simulated in accordance with a bio-optical radiative transfer model (RTM). Correspondingly, four kinds of empirical bathymetry's model calibration data are referred to as altimeter data, photogrammetric data, chart data, and RTM data, respectively. The objective of this article is to assess the similarities, differences, limitations, and applicability of these four kinds of possible model calibration data, in order to know which of them is most suitable for a certain empirical bathymetry task. WorldView-2 and Sentinel-2A multi-spectral images covering four typical shallow water areas in Hawaii and Xisha Islands and Stumpf's logarithmic band ratio model were used to compare and contrast the bathymetric performance of these four kinds of possible model calibration data. The result showed that all four kinds of possible model calibration data can be used for satellite-derived empirical bathymetry when the high-quality in-situ depth data are not provided, but they will provide different bathymetric accuracy values. According to five evaluation indexes (i.e., bathymetric performance, data availability, data quality, complexity of data generation, and data adaptability), the altimeter data perform best, the chart data perform second best, the RTM data follow with the third performance, and the photogrammetric data perform markedly worse than other three kinds of model calibration data. Such factors as the in-situ property, spatial coverage, co-registration and independence of model calibration data must be taken into consideration as well during a model calibration data selection. [ABSTRACT FROM AUTHOR]

Effective coverage path planning for USVs is essential to optimize the performance of bathymetric surveys. Traditionally, it is well recognized that the best sweep direction for coverage path planning is the parallel direction that finds the minimum span of the region of interest (ROI). However, the results in this paper first reveals that it is not always the case when the water current is involved. In this paper, we first formulate an energy consumption estimation model for USV and introduce a novel coverage path planning strategy. Then, we investigate the relationship between sweep direction and USV energy consumption under the influence of water currents, referred to as the E - β curve. We then systematically analyze the variations of the E - β curve under different shapes of ROIs, various water current attacking angles, and different coverage strategies. Finally, the model is extended to more realistic scenarios involving non-convex ROIs. The practicality of the model is validated USV semi-physical model. The results indicate that, under water currents, our proposed model allows for an optimal sweep direction that minimizes the energy consumption of USVs. This contrasts with traditional methods, which fail to achieve the optimal energy cost. The results hold significant implications for the design of USV mapping strategies in inland river. • This paper is the first to unveil the relationship between sweep direction and USV energy consumption under water currents, referred to as E - β curve. • Systematical analysis has been conducted on the factors that may impact the E - β curve. • An energy consumption estimation model for USV is constructed. • The model is extended to realistic scenarios involving non-convex polygonal ROIs and semi-physical simulation. [ABSTRACT FROM AUTHOR]

Monocular 3D object detection aims to localize objects in 3D space from a single image. This is a difficult problem due to the lack of accurate depth measurements. Many methods predict depths upfront using a pre-trained vision-based depth estimator to assist in 3D object detection. However, the methods show limited improved performances because of the depth inaccuracy and the neglect of depth confidence. In this paper, we propose a new end-to-end 3D object detection framework by combining a monocular camera with a cheap 4-beam LiDAR. The minimal LiDAR signal is leveraged as an additional input to predict high-quality and dense depth maps from monocular images. Meanwhile, several 3D proposals are generated by a keypoint-based detector. The key challenge is encoding the depth confidence to capture the depth estimation uncertainty. Therefore, we propose probabilistic instance shape reconstruction to exploit instance shape information for box refinement. Our method employs a fully differentiable end-to-end framework, making it simple and efficient. The experimental results on the KITTI dataset demonstrate that the proposed method achieves state-of-the-art performance, thus validating the effectiveness of the sparse LiDAR data and the probabilistic instance shape reconstruction. Code is available at https://github.com/xjtuwh/SparseLiDAR_fusion. [ABSTRACT FROM AUTHOR]

Terrain-aided navigation (TAN) is one of the key techniques for autonomous navigation and positioning of AUVs. This paper develops a novel integrated navigation system that combines the inertial navigation system (INS) and TAN into one filter, in contrast to the conventional INS/TAN model. This method not only provides a position estimate for the carrier but also the INS error, which increases the filtering dimension significantly. Thus, the Rao-Blackwellized particle filter (RBPF) technique is introduced to address the "dimensional disaster" problem. A three-dimensional (3-D) model is established to estimate the horizontal position while compensating for the tidal inaccuracy by extending the tidal depth bias to the state space. Furthermore, the variable and complex underwater environment can potentially result in outlier interference in depth measurements, which significantly degrades the performance of the RBPF-based estimation algorithm. This paper thus presents a 3-D adaptive RBPF method based on the maximum correntropy criterion (MCC) to suppress the influence of measurement outliers on positioning precision. Simulations and experimental tests verify the effectiveness of the proposed algorithm. The results demonstrated that the 3-D model-based AMCCRBPF method can effectively improve robustness to outliers and provide an accurate estimate of the tidal depth bias. • A tightly integrated INS and TAN system is created to enhance algorithm stability when tide information is inaccurate. • Based on the MCC, the likelihood function is improved to enhance the estimation accuracy of nonlinear states. • Adaptive estimation of noise characteristics is done to enhance the accuracy of linear state estimation. [ABSTRACT FROM AUTHOR]

• The principal purpose of this paper is the development in numerical treatments for the resonance problem of multi-phase systems by constructing a well-balanced finite volume scheme for two-dimensional shallow water equations with variable topography. • This scheme is constructed based on exact solution of local planar Riemann problems at each grid cells. • The well-balancedness of this scheme is shown in the sense that it can preserve exactly the lake at rest solution over both smooth and non-smooth bottom. • Several numerical experiments related to steady and time-dependent problems are conducted to show the potential of this approach. • The remain challenges are the ineffectiveness of this scheme towards time-dependent solutions throughout a long process and the instability of errors caused by the relaxation while coding. • This work provides an impetus to enhance the performance of this scheme for time-dependent solutions, and motivates further studies in numerical treatments of the resonance problem for multi-phase flow models as well. We consider in this paper a finite volume scheme based on local planar Riemann solutions for the two-dimensional shallow water equations with bathymetry. The model involves a nonconservative term, which often makes standard schemes difficult to approximate solutions in certain regions. The scheme to be presented is a development of the preliminary works that will be cited below. Our foremost purpose is to extend those results to two-dimensional formalism while preserving the physical and mathematical properties, including the well-balancedness. The proposed scheme is applied to some specific families of solutions, especially lake at rest and partially well-balanced solution. The numerical results show that this approach can give a good accuracy, except for resonant cases. Furthermore, it is proved that our finite volume scheme can preserve the C -property in the sense that it can capture exactly the lake at rest solution. [ABSTRACT FROM AUTHOR]

Bathymetric data is crucial for navigation safety and various applications. However, only a small portion of the seafloor has been systematically mapped through direct measurement. The remaining bathymetry is estimated from satellite altimeter data, providing only an approximate representation of the seafloor's shape. To address this issue, the convolutional neural network (CNN) is introduced for the analysis of seabed topography. To the best of our knowledge, this marks the first attempt to incorporate the CNN into the definitive map of the world ocean floor. By employing skip connections based on residual learning, we construct a deeper CNN layer that effectively reduces training complexity. The deeper convolutional neural network layer is used to create a more complex nonlinear mapping model, which is then employed to downscale low-resolution seabed topographic data in order to obtain high-precision seabed topographic information. This process enhances the representation of seabed topographic data to reflect the actual terrain more accurately. The results are compared with those obtained using the bicubic difference method. Conducting tests near the Gulf of Thailand, where Malaysia Airlines Flight MH370 was lost, the results demonstrate that the method proposed in this paper achieves higher accuracy in processing the downscaling of seabed topographic data. • Convolutional neural networks refine seabed terrain does not direct electromagnetic detection. • The first attempt to incorporate a CNN into the final map of the world's seabed. • Basic application of artificial intelligence algorithms in "smart ocean". • Specific application of seabed research in the missing area of Malaysia Airlines Flight MH370. • It contributes a new idea to the global seabed geomorphologic map. [ABSTRACT FROM AUTHOR]

A robust mathematical model is presented in this paper for the multi-connected domain with variable bathymetry using dual reciprocity boundary element method (DRBEM) to analyze the combined effects of wave diffraction-refraction and reflection on the arbitrarily shaped harbor. The influence of sloping bathymetry and the impact of the bottom friction on the harbor resonance are investigated. The fluid domain is primarily separated into two regions Region-I (open sea region) and Region-II (harbor region). Further, Region-II is divided into multi-connected regions. The mild slope equation is rearranged to obtain the non-homogeneous Helmholtz equation, and utilizing the ordinary boundary element method to this non-homogeneous equation, the non-homogeneous part will convert into a domain integral. The present model is verified by comparing it with the analytical examination of Wang et al.2015; Shao et al.2017. The wave amplification is determined for the T-shaped and TT-shaped domains to analyze the influence of bottom friction, and slopping bathymetry. Further, the present numerical approach is employed to the realistic port, Visakhapatnam port, India, and the four key locations are identified to analyze harbor resonance in the bottom friction and slopping bathymetry of the multi-connected region. • A Dual reciprocity boundary element method (DRBEM) with wave diffraction-refraction on the arbitrarily shaped harbor. • The influence of sloping bathymetry and effect of the bottom friction is also investigated. • Wave Amplification of the T-shaped and TT-shaped domains to analyze the influence of bottom friction, and bathymetry. • Implemented on the realistic Visakhapatnam port, Andhra Pradesh, India. • To analyze the harbor resonance on slopping bathymetry and effectively for redesigning, renovating and constructing ports. [ABSTRACT FROM AUTHOR]

This paper aims to explore the effects of earthquakes on the properties of medium-height reinforced concrete houses in China. The results demonstrated a significant decrease in ultrasonic resonance frequency, indicating structural damage, with reductions of 26.5 %, 30.2 %, and 37 % observed for earthquakes of magnitudes 5.0, 5.3, and 5.7, respectively. Similarly, the dynamic modulus of elasticity exhibited a reduction of over 50 %. Measurements of carbonation depth revealed values of 34.65 mm, 38.97 mm, and 46.12 mm for earthquakes of magnitudes 5.0, 5.3, and 5.7, respectively. Accordingly, the percentage of mass loss amounted to 22.17 %, 36.87 %, and 49.78 %. Furthermore, experiments identified the least favourable outcomes during maximum seismic activity, with a recorded peak stress of 447.3 MPa at a deformation of 0.63 mm. These findings contribute to a better understanding of the impact of seismic events on reinforced concrete structures and the associated corrosion mechanisms. [ABSTRACT FROM AUTHOR]

Abstract This paper deals with the implementation of a new, efficient, non-perturbative, Hamiltonian coupled-mode theory (HCMT) for the fully nonlinear, potential flow (NLPF) model of water waves over smooth, single-valued, but otherwise arbitrary bathymetry Papoutsellis and Athanassoulis (2017). Applications considered herein concern the interaction of solitary waves with bottom topographies and vertical walls both in two- and three-dimensional environments. The essential novelty of HCMT is a new representation of the Dirichlet-to-Neumann operator, which is needed to close the Hamiltonian evolution equations. This new representation emerges from the treatment of the substrate kinematical problem by means of exact semi-separation of variables in the instantaneous, irregular, fluid domain, established recently by Athanassoulis and Papoutsellis (2017). The HCMT ensures an efficient dimensional reduction of the exact NLFP, being able to treat a variable bathymetry as simply as the flat-bottom case, without domain transformation. A key point for the efficient implementation of the method is the fast and accurate evaluation of the space–time varying coefficients appearing in some of its equations. In this paper, all varying coefficients are calculated analytically, resulting in a refined version of the theory, characterized by improved accuracy at significantly reduced computational time. This improved version of HCMT is first validated against existing experimental results and other computations, and subsequently applied to new solitary wave-bottom interaction problems. The latter include: (i) the investigation of a new type of “Bragg scattering” effect, appearing when a solitary wave propagates over a seabed with a sinusoidal patch, and (ii) the disintegration, focusing and reflection of a solitary wave moving over a three-dimensional bathymetry consisting of parallel banks and troughs, and impinging on a vertical wall. Highlights • Development of a dimensionally reduced model describing fully nonlinear water waves. • Analytic calculations of equations2̆019 coefficients allow for efficient simulations. • Applications to solitary waves and validations against several experiments in 1D. • Investigation of a new solitary wave-undulating bottom interaction. • Transformation of a solitary wave due to a 3D bathymetry. [ABSTRACT FROM AUTHOR]

This paper proposes an accurate and applicable online measurement method of wear depth using displacement signal for vertical testers under mixed lubrication. Firstly, displacement signal is revealed to be composed of temperature drift and Brownian motion. Secondly, the first order Taylor expansion of the Brownian motion is revealed to be the unified form of wear models. Further, the online measurement method is established by introducing non-integer order and amplitude coefficient to eliminate systematic randomness. Finally, the method is verified by graphite-metal tribo-pairs on a standard tester and a high speed friction and wear testing bench, relative errors between online and offline measurement results are less than 10 %, extension errors by non-integer order within its application range are less than 2 %. • Revealing the components of measured displacement signal consisting of temperature drift and Brownian motion. • Proposing a unified form of wear models. • Establishing online measurement algorithm and operation flow. • Verifying accuracy and applicability of the online measurement method. [ABSTRACT FROM AUTHOR]

The lack of three-dimensional (3D) information limits the popularization and development of holographic technology. This paper proposes a low-cost, high-precision integral 3D real scene photography and holographic 3D display system using active fringe projection. The system solely relies on a projector, a CCD camera, and a computer to swiftly and accurately acquire 3D information (accuracy within 2 mm) through Fringe Projection Profilometry. Then, significantly effective 3D holographic reconstruction is achieved using a layer-based algorithm. Finally, the energy of image gradient operator is used to calculate the focus measurement of the image, and the change of the focus region is quantitatively analyzed. The performance of the system was tested using a box, and the experiment results were consistent with the simulation results, verifying the feasibility of the system. This method will further expand the application of holographic technology in medicine, the military, navigation, and other fields. 3D holographic display has been widely used in education, medical science, military and other fields, and has a very promising prospect of application. At present, the methods of the acquisition of 3D content used for 3D holographic reconstruction has the problems of high system complexity, high cost and low precision. To address this issue, this work proposed a low-cost, high-precision 3D real scene photography and holographic 3D display system using active fringe projection. The system solely relies on a projector, a CCD camera, and a computer to swiftly and accurately acquire 3D information (accuracy within 2 mm) through Fringe Projection Profilometry. Then, significantly effective 3D holographic reconstruction is achieved using a layer-based algorithm. Finally, the energy of image gradient operator is used to calculate the focus measurement of the image, and the change of the focus region is quantitatively analyzed. The performance of the system was tested using a box, and the experiment results were consistent with the simulation results, verifying the feasibility of the system. Compared with other methods, this method is simple, low-cost and high-precision (depth measurement accuracy within 2 mm). This work will further expand the application of 3D holographic display in the field of medicine, the military, navigation, industrial applications (industrial inspection, head-mounted displays etc.) and other fields. [ABSTRACT FROM AUTHOR]

The use of LiDAR as an alternative to an array of in-situ instruments for water elevation measurement, specifically in the surf zone, is covered in detail. This paper outlines the advances in remote sensing of the coastal environment and provide both laboratory and field observations obtained through the application of LIDAR scanning devices. The results of this paper show a good correlation between LiDAR and pressure transducer measurements of water elevation in both a wave flume and within the surf zone (mean coefficient of determination of 0.76 and 0.89 respectively). The water surface reflectivity of the study area needs to be maximised in order for the LiDAR to provide suitable measurements, therefore a method of seeding in the wave flume is described. Points to consider for the setup of the LiDAR instrument in both the laboratory and the field are discussed, as well as the influence that wave parameters such as wave height and wave period have on the quality of results. Free surface elevation data across the spatial and temporal domain can be obtained with LiDAR and used for a wide range of wave analyses. [ABSTRACT FROM AUTHOR]

Coastal erosion is a major problem for shorelines everywhere in the world. In order to mitigate beach stability problems it is necessary to determine the equilibrium shape of the beach planform. Current equilibrium planform shape equations are only valid under certain simplifications; for instance, they are unable to predict the effect of nearshore islands and/or rocky bottoms, as well as the effect of several diffraction points. The aim of this paper is to present a new process-based shape equation that is able to overcome those limitations and estimate the static equilibrium shoreline of complex bathymetry beaches. The equation is based on the hypothesis that a pocket beach gets its static equilibrium planform when the mean surf-zone longshore velocity averaged over a period of time is null ( V ¯ = 0 ) in every point along the beach. Based on this hypothesis, the direction of the shoreline that nulls the mean surf zone longshore velocity along the beach is evaluated. Therefore, the shape equation is based on the longshore current velocity formula. The new equilibrium shape equation is applied to two Spanish beaches, namely Milagro beach and Cala Millor beach. Milagro beach has a very smooth bathymetry and the parabolic shape equation developed by Hsu and Evans (1989) is able to predict the equilibrium shoreline. Cala Millor is more complex: it has some rock outcrops along the beach and the parabolic shape equation does not work. The equilibrium shape equation presented in this paper simulates the equilibrium shoreline of both beaches successfully with a high R 2 (around 0.96) between the modelled shoreline and the real shoreline in both case studies. [ABSTRACT FROM AUTHOR]

While photogrammetry is widely implemented in fields such as archaeology and cultural heritage, the accuracy of this method has yet to be fully addressed. It is imperative that digital photogrammetry models depicting sites of cultural heritage have accurate dimensions to avoid misunderstandings and incorrect analysis. This paper outlines a new method for minimizing the adverse effects of bias and low repeatability precision in photogrammetry software. Specifically, this paper quantitatively addresses the effects of systematic error during scaling of digital photogrammetry models as well as the random error due to a repeatability issue inherent to photogrammetry software. The method was developed using statistical analysis and robust uncertainty calculations and validated through multiple case studies. [ABSTRACT FROM AUTHOR]

This study introduces an innovative technique specifically designed to effectively mitigate multibeam sonar noise in intricate scenarios where conventional denoising methods have typically faltered. These traditional methods have historically struggled to maintain a delicate balance between sensitivity, specificity, and interpretability, leading many cartographers and research professionals to resort to laborious and time-consuming manual processing techniques. In response to this prevalent challenge, we meticulously formulated a mathematical model to represent each individual step involved in the manual editing process. The approach involves parameterization of cartographers' perceptual manipulation, resulting in a novel noise rejection methodology. A notable attribute of this method is its simplicity and intuitive nature; users are required to set only a handful of fundamental parameters to obtain highly accurate processing results. Importantly, this technique spares the data from exposure to linear filters such as lowpass or average filters, enhancing the fidelity and reliability of the results. Furthermore, our proposed method retains the interpretability of the processed seafloor bathymetry as it abstains from implementing opaque methodologies such as Neural Networks. This aspect of the technique makes it an ideal choice for researchers and cartographers who prioritize understanding the underlying processes affecting their data. In the discussion segment of this paper, we present a quantitative comparison of the data processed by manual edit, the commercially mature algorithm, and our newly proposed method. This comparison underscores the superior performance and effectiveness of our technique, further reinforcing its potential applicability in real-world scenarios. • MBES denoising method, turning manual editing procedures into a mathematical model. • Using intuitive parameters, keeps high accuracy, clarity and interpretability. • Tested on various terrains, showing high universality and reliability. [ABSTRACT FROM AUTHOR]

The scattering of nonlinear and non-breaking surface gravity waves propagating over a three-dimensional varying bathymetry is considered in this paper. In a recent study (Gouin et al., 2016) two numerical schemes for propagating waves over a variable bottom in an existing High-Order Spectral (HOS) model have been introduced. Both the computational effort and the accuracy of the model were shown to be conserved with the introduction of these new schemes. Moreover, they have been extensively validated in 2D, but the propagation of regular and irregular waves over 3D varying bottoms remains to be addressed with such spectral methods. In this paper, the three-dimensional formalism is introduced as well as the practical implementation of 3D configurations. Then the method is applied to a three-dimensional varying bathymetry consisting of an elliptical lens, as used in the Vincent and Briggs (1989) experiment. Incident waves passing across the lens are transformed and a strong convergence region is observed after the elliptical mound. The wave amplification depends on the incident wave. Numerical results for regular waves, unidirectional and directional irregular waves are analysed and compared with experimental data, demonstrating the efficiency and practical applicability of the present approach to treat the nonlinear propagation of various sea states over a varying bathymetry. [ABSTRACT FROM AUTHOR]

RGB-D cameras such as RealSense and Structure Sensors have been widely used in most robotics systems. This paper presents a system for estimating the trajectory of an RGB-D camera and IMU in indoor environments. The system uses a novel relative pose estimation method that utilizes depth measurements and epipolar constraints for initialization. An adaptive depth estimation method is also proposed, which fuses a depth uncertainty model and multi-view triangulation. In the backend, a sliding window framework is used to optimize the system state by minimizing the residuals of pre-integrated IMU, 3D features re-projection, and 2D features epipolar constraint. The effectiveness of the system is evaluated using publicly available datasets with ground truth trajectories. • This paper uses the depth uncertainty model of the depth camera to divide feature point pairs into 3D–3D and 2D–2D pairs based on their depth measurement noise. A robust pose estimation method is then introduced to fuse 3D–2D and 2D–2D constraints for initialization. • An adaptive depth estimation method is proposed, which combines the depth uncertainty model and multi-view triangulation to achieve high-precision feature point depth estimation. • The paper presents a nonlinear optimization framework in the backend that combines epipolar and re-projection constraints. [ABSTRACT FROM AUTHOR]

Tidal turbines at sea are subject to complex flow conditions. Among that complexity, wide bathymetry obstacles can generate powerful coherent flow structures whose impact on horizontal axis tidal turbines was proved to be highly detrimental. Consequently, the present paper aims at studying the effects of such coherent flow structures on the response of another tidal turbine geometry, namely a bottom-mounted ducted twin vertical axis tidal turbine (2-VATT). We tested a 1/20 scale model of such a 2-VATT in Ifremer's flume tank either with a flat bed or downstream of a wide bathymetry obstacle at a constant far upstream velocity and we measured the turbine response simultaneously with the flow velocity. These flow measurements make it possible to compute cross-correlations in order to analyse the influence of the velocity fluctuation on the turbine response. The results reveal a strong drop in the average power and loads coefficients of the 2-VATT combined with significantly larger fluctuation. The velocity deficit and the high level of turbulence in the obstacle wake is responsible for a 40% lower average power coefficient and more than 3 times higher standard deviation compared to the flat bed configuration. The loads standard deviations are multiplied by 2 for the drag and by 10 for the lift when the 2-VATT is downstream of the bathymetry obstacle. This behaviour strongly increases the risks of structural fatigue failure, but the turbine drifting or overturning risks under those conditions remain lower than with the flat bed. The power fluctuation increase appears to be mostly due to the flow shear in the obstacle wake whereas the load fluctuation is mostly due to the periodical passing of the coherent flow structures. Thus, a proper characterisation of the flow at each precise turbine locations prior deployment at sea is highly recommended to design their structure accordingly. • Vertical axis turbine in the wake of uneven bathymetry generating flow variation. • Obstacle wake induces strong drop in the average power and loads coefficients. • Sheared flow and turbulence extend the torque and power fluctuations. • Coherent flow structures induce load fluctuations. [ABSTRACT FROM AUTHOR]

There is a pressing need for a fast and efficient satellite remote sensing tool to estimate coastal bathymetry for any coastline in the world. To date, satellite methods for deriving bathymetry have mainly focused on linking the radiometric response to a known water depth, as with SPOT, Landsat and Sentinel. Here, wave properties (static and dynamic) are approximated using the small time delay between the different color bands of Sentinel-2 to then calculate a depth using wave linear dispersion theory. In this paper, we present a spatial correlation method within the S2Shores (Satellites to Shores) Python toolbox: a processing chain/toolbox of coastal observations using methods applied to optical satellites. The resulting individual bathymetries are finally qualified according to the standards of the International Hydrographic Organization, anticipating their operational use. • S2Shores spatial-correlation method for optical satellite coastal observations. • Bathymetry qualified with the International Hydrographic Organization standards. • Wave characteristics from the time delay between spectral bands of Sentinel-2. [ABSTRACT FROM AUTHOR]

With portable and cost-effective attributes, unmanned surface vehicles (USVs) are becoming a crucial role in coastal bathymetric surveys. However, in practical applications, the deployment of USVs for bathymetry encounters challenges from multiple facets, including intricacies of coastline shapes, determination of optimal coverage paths, and the sub-region sequencing. To address these issues, this paper introduces a novel coverage planning scheme designed for a coastal bathymetric survey in a lake region. The scheme commences with the Control Point Douglas-Peucker algorithm that effectively utilizes control points to envelope complex coastal lines, ensuring coastline accuracy while facilitating cellular decomposition. Subsequently, an optimal coverage strategy, characterized by fast convergence, complete coverage, and solution optimality, is meticulously designed to generate the most effective back-and-forth survey paths. Finally, by applying the mapping mechanism and fuzzy rules, a Fuzzy Biased Random Key Evolutionary Algorithm is devised to determine the optimal sequence of survey areas. Extensive simulation studies and comparative evaluations substantiate the superiority of the proposed scheme over existing state-of-the-art methods across various problem variants. In addition, real-world lake trials with USV SL-20 are conducted, providing empirical validation and emphasizing the augmented practicality of implementing the proposed methodology in engineering applications. • A Control Point Douglas-Peucker method is proposed to approximate the intricate coastal lines. • A novel coverage strategy is designed to achieve fast convergence, solution optimality, and complete coverage. • A Fuzzy Biased Random Key Evolutionary Algorithm is proposed to determine the mapping sequence of sub-regions. • The practicability is validated through lake trials using USV SL-20. [ABSTRACT FROM AUTHOR]

With the development of photon-counting sensors, spaceborne photon-counting lidars have shown many advantages in mapping underwater topography. Although a space based lidar is normally a profiling system, the depth penetration and the vertical accuracy achieved with a bathymetric lidar is superior to imagery (that only provides relative depths). Therefore, many satellite derived bathymetry products use both active/passive spaceborne data to achieve spatial coverage as well as absolute depth measurements. Compared with shipborne and airborne bathymetric systems, satellite derived bathymetry data can have a global coverage, especially covering some remote areas where airborne/shipborne systems are hard or very expensive to reach. In this paper, a theoretical model is proposed to quantitatively analyze the maximum bathymetric depth of a satellite photon-counting lidar, which considers the system parameters, environmental effects, and the constraint of the SNR (signal to noise ratio). System parameters of ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) as well as the MODIS (Moderate-resolution Imaging Spectroradiometer) and NCEP (National Centers for Environmental Prediction) datasets are used to provide systematic and environmental inputs to the model, and the ICESat-2 actual bathymetric data are used to verify the maximum depth estimated by the proposed model. In six different sites with different water qualities, solar angles and wind speeds, the theoretical maximum bathymetric depths agree well with the actually achieved ICESat-2 lidar depths, in terms of MAE (mean absolute error) of 0.50 m and the RMSE (root mean square error) of 0.60 m. The errors in all study areas are within 14% of the corresponding maximum depths. Additionally, the non-linear response of a photon-counting lidar, independent parameter impacts on the theoretical model, and the errors in the experimental process were quantitatively analyzed. In the future, this theoretical model can be used to evaluate the maximum bathymetric depth for a bathymetry investigation when applying system parameters and environmental parameters. In addition, it can be used to optimize the hardware parameters of a photon-counting lidar in its early design process. [ABSTRACT FROM AUTHOR]

Acoustic methods for seafloor mapping have been widely developed over the last decades. In particular, the development of swath bathymetry has allowed the creation of detailed maps of seabed topography and acoustic backscatter data; these data have been used to infer sediment and habitat types. In this paper the capability of Multi-Beam Echo Sounder (MBES) system data to distinguish different seabed types in a site in the Tyrrhenian Sea (Mediterranean) is evaluated; dataset used includes bathymetric data and backscatter intensity, with the support of sediment samples and scuba investigations. The Reson SeaBat 8125 MBES system provides bathymetric and backscatter data. The backscatter data are stored both as Sidescan-like data (intensity values produced by an averaging process) and Snippet data (a time-series of intensity values for each beam). The processing of these acoustic data belongs to a relatively new field of research: the aim of this paper is to show two different processing approaches, and discuss the produced output. The mosaic of images from the Sidescan-like and Snippet data are statistically analyzed, in order to highlight the resolution of the Snippet when dealing with acoustic facies and the correlation existing between granulometric features and the recognized facies. In conclusion, even if no signal appears to be better than the other, it is evident that both Sidescan-like and Snippet data are complementary to a correct interpretation of the seafloor features and can produce a highly detailed acoustic mosaic useful for several scientific areas, including habitat mapping. [ABSTRACT FROM AUTHOR]

In this paper, the half-skip configuration of the Total Focusing Method (TFM) is used to image and size surface-breaking cracks. The TFM is an ultrasonic array post-processing technique which is used to synthetically focus at every image point in a target region. This paper considers the case of inspecting for cracks which have initiated from the far surface of a parallel-sided sample using an array on the near surface. Typically, only direct ray paths between the array and image points are included in the TFM algorithm and therefore the image obtained for this case consists only of root and tip indications; no specular reflection from the crack faces is captured. The tip indication often has such a poor signal-to-noise ratio that reliable crack depth measurement is challenging. With the Half-Skip TFM, instead of using directly-scattered signals, the image is formed using ultrasonic ray paths corresponding to the ultrasound that has reflected off the back surface and has then undergone specular reflection from the crack face back to the array. The technique is applied to experimental and simulated array data and is shown to measure the depth of small cracks (depth <1 mm) with greater reliability than methods which rely on tip diffraction. [ABSTRACT FROM AUTHOR]

Instruments measuring surface topography with nanometre accuracy are essential tools for studying nanotechnology. Despite their maturity, erroneous observations due to various error sources are widespread, particularly due to calibration and traceability issues. The current method of vertical scale calibration (which is one of the error sources), relies on the depth standard method that limits the traceability of the instrument to the calibrated range determined by the minimum and maximum discrete values. This paper reports a new method relying on the tilted flat that was aimed at mapping the linearity deviations continuously within the range covered by the tilt angle. The full traceability in this case requires only the measurement of a single depth measuring standard, that can be optimally selected to achieve least uncertainty associated with the amplification coefficient of the scale. The proposed method opens the opportunity for high dynamic range calibration, currently unachievable with conventional calibration techniques. Image 107880 • Surface texture instruments' linearity comprehensively estimated. • Complete information about linearity deviation and its associated PDF. • Simple line profile measurements provide info for in-line uncertainties. • Estimate the linearity for deriving uncertainties at nanometre scale. • Estimate linearity at micro- and millimetre scales with small uncertainties. [ABSTRACT FROM AUTHOR]

The safeguard of existing masonry buildings requires a meticulous characterisation of the component materials (units and mortar) by using in-situ minimally intrusive techniques. This need is especially prominent in the case of heritage buildings in order to minimize their damage and alteration. This paper presents a research on some minor destructive techniques (MDT) for the in-situ evaluation of the mechanical properties of masonry components. In the research, the results derived from MDT were empirically correlated with the compressive strength obtained by using well-known destructive testing (DT) techniques executed in the laboratory. The experimental campaign focused on two different MDT techniques, namely the Pin Penetration Test (PPT) and the Helix screw Pull-out Test (HPT). The PPT is based on the measurement of the depth of penetration of a steel pin. The HPT is based on the measurement of the pull-out load necessary to extract a steel tie inserted into a hole drilled in a brick or in a mortar joint. The experimental campaign also included an evaluation of the Double Punch Test (DPT) by comparison with strength values obtained from mortar specimens prepared and tested following the standard EN 1015–11. The experimental results show a satisfactory agreement between the MDT measurements and the compressive strength obtained with DT. Although both the PPT and HPT are useful for the evaluation of the compressive strength of masonry components, the former exhibits a lower scattering in the experimental measurements. • 541 destructive tests on modern and historical solid clay bricks and mortar joints. • 741 minor destructive tests on solid fired clay bricks and mortar joints. • Compressive strength in mortar using Double Punch Test and EN 1015–11 procedure. • Compressive strength evaluation of specimens using the Pin Penetration Technique. • Compressive strength evaluation of specimens using the Helix screw Pull-out Test. [ABSTRACT FROM AUTHOR]

[Display omitted] Lake Urmia, once the second-largest saline lake worldwide, has almost dried. Several studies have provided bathymetric maps for the lake using different data and techniques but rarely identified the associated uncertainties. This paper provides a comprehensive review of Lake Urmia bathymetric studies and discusses the underlying uncertainties. We developed an updated hybrid bathymetry and hypsometric relationships for Lake Urmia using in-situ and satellite data. The proposed hybrid bathymetry was validated against independent in-situ depth data (with an RMSE < 20 cm) and applied as a baseline for comparison with other available bathymetry models. Results revealed that uncertainties in lake depth measurement, water delineation algorithms from satellite data, spatial interpolation method, and sensor resolution have the highest uncertainty, respectively. Furthermore, the width of the uncertainty bands in the lake level-area relationships is not uniform and peaks at lake levels between 1270 and 1272 m, which are critical for conserving crucial ecosystem services of Lake Urmia, such as island conservation and dust control. Our synthesis indicated that the application of various Lake Urmia bathymetries could lead to about 0.5 and 1 km3 differences in the estimated lake volumes for obtaining the ecological and dust control levels, respectively. Our findings provide useful insights for Lake Urmia managers, also applicable for other saline lakes, into considering the dynamic of lake topography and associated uncertainties in lake conservation/restoration programs. [ABSTRACT FROM AUTHOR]

In this paper, the effects of regular waves propagating against the current on the wake of a wide bathymetric obstacle are experimentally investigated. For that purpose, a square cylinder of height representing 1 / 8 t h of the water column, mounted perpendicular to the flow, is used. Both Reynolds and Froude numbers are close to the ones encountered at sea and swell properties (amplitude, frequency and wavelength) which are typical conditions in the English Channel. To study this complex hydrodynamic interaction, PIV measurements are used to capture the velocity field around and in the wake of the cylinder. The wake of this wide cylinder has been extensively studied and is characterised by its direction towards the water surface and by energetic and wide vortices arising from the sheared layer at a Strouhal number of approximatively 0.06, after a merging of smaller eddies. In this work, the focus is on how surface gravity waves, propagating against the current, modify the generation of these turbulent structures. The results show that the cylinder wake is strongly modified in the presence of waves, even if, on average, the main wake structure is globally conserved. The waves act both on the vortex generation and the wake development with modifications in terms of turbulent energy distribution and level, wake recovery and ascent rate. The vortex shedding becomes highly energetic and well-organised from the cylinder position. Its return period is extremely regular and corresponds to half of the wave frequency which is really close to the natural vortex shedding frequency. That results in a doubling of the statistical length scale of the vortices. • Swell induced-motion effects on high and isolated bathymetry roughness. • Bottom mounted cylinder wake characterisation in presence of waves opposing current. • Vortex generation and dynamic study. • Energy transfer between wave and vortex shedding frequency in the near-wake. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we describe the variation in myctophid schools characteristics at South Georgia using multi-frequency acoustic data collected annually between November 2007 and January 2012. We studied the relationship between the proximity of land and the distribution and schooling characteristics of myctophid fish. We also examined patterns in schooling behaviour in relation to oceanographic data. Fish schools were identified using a dual-frequency dB identification method (S v120−38 kHz), where negative S v120−38 kHz is indicative of gas-bearing organisms, such as swimbladdered fish. Available net data were used to provide information on the meosopelagic fish community in the region. School morphometrics (e.g. length, thickness, area) data were extracted and pooled according to their distance from the shore (0–30km, 30–60km, 60–90km, 90–120km). A total of 578 schools were detected in the survey region and there was high variation in school backscattering strength (NASC), length, height, perimeter, depth and horizontal distribution between surveys, including distinct inter-annual variation in these parameters when surveys were conducted in the same season (2009–2012). Schools were distributed predominantly on-shelf (0–500m isobaths) during some summer surveys (2007 and 2012) and predominantly off-shelf on others (>500m isobaths; 2009, 2010 and 2011). There was also evidence of bathymetric separation in the horizontal distribution of schools. Schools observed in the late-season in 2008 had the greatest NASC, largest height and the deepest depth distribution. Most schools occurred at depths between ∼60 and 300m, but they did not occupy the same water masses during each survey. Schools became progressively thinner, shallower and acoustically weaker with increasing distance to land, whilst school length and perimeter increased correspondingly. The change in fish schooling behaviour between environments could be a response to a combination of local predatory threats over short spatial/temporal scales and differences in oceanographic conditions, such as current velocity. The trend could also be evidence of spatial habitat partitioning of myctophids, with different schooling species, or different life-stages, orientating along a bathymetric gradient at South Georgia. [Copyright &y& Elsevier]

Abstract: The study of contourite drifts is an increasingly used tool for understanding the climate history of the oceans. In this paper we analyse two contourite drifts along the continental margin west of Spitsbergen, just south of the Fram Strait where significant water mass exchanges impact the Arctic climate. We detail the internal geometry and the morphologic characteristics of the two drifts on the base of multichannel seismic reflection data, sub-bottom profiles and bathymetry. These mounded features, that we propose to name Isfjorden and Bellsund drifts, are located on the continental slope between 1200 and 1800m depth, whereas the upper slope is characterized by reduced- or non-deposition. The more distinct Isfjorden Drift is about 25km wide and 45km long, and over 200ms TWT thick. We revise the 13 years-long time series of velocity, temperature, and salinity obtained from a mooring array across the Fram Strait. Two distinct current cores are visible in the long-term average. The shallower current core has an average northward velocity of about 20cm/s, while the deeper bottom current core at about 1450m depth has an average northward velocity of about 9cm/s. We consider Norwegian Sea Deep Water episodically ventilated by relatively dense and turbid shelf water from the Barents Sea responsible for the accumulation of the contourites. The onset of the drift growth west of Spitsbergen is inferred to be about 1.3Ma and related to the Early Pleistocene glacial expansion recorded in the area. The lack of mounded contouritic deposits on the continental slope of the Storfjorden is related to consecutive erosion by glacigenic debris flows. The Isfjorden and Bellsund drifts are inferred to contain the record of the regional palaeoceanography and glacial history and may constitute an excellent target of future scientific drilling. [Copyright &y& Elsevier]

In the present paper results concerning the implementation of the Glow Discharge Optical Emission Spectrometry (GDOES) for measure the He depth profile within W coatings are given. The He emission line situated at 587.5 nm was used in this respect. W coating containing He up 10 at.% and with thickness of 5 μm have been obtained by Combined Magnetron Sputtering and Ion Implantation (CMSII) method. The coatings structure and morphology was investigated using Scanning Electron Microscopy (SEM) measurements. The He retention within the coatings was evaluated by using Thermal Desorption Spectroscopy (TDS). Time-of-Flight Elastic Recoil Detection Analysis (TOF ERDA) measurements has been used to determine chemical composition of the coatings. Results of TOF-ERDA measurements results were used to calibrate the GDOES equipment. Using these data the GDOES depth profiles of the He within W coatings have been obtained. • W coatings with He content have been produced. • The obtained He content within the coatings was 10.7 at.%. • A GDOES depth profile of the He within the W coatings have been obtained. [ABSTRACT FROM AUTHOR]

The demand for dimensional micro and nano metrology is evident, and with the miniaturization process of microstructures and the trend towards using polymer material, the available technologies are imperative. This paper proposes a quantitative depth evaluation method for microgrooves with width less than the diffraction limit and a measurement system capable of depth detection on polymer materials. The depth of microgrooves can be quantitatively related to the near-field optical phase difference, which cannot be practically observed but can be computed from practical far-field observations by proposed depth evaluation method. The developed measurement system uses low-coherence illumination to reduce the spatial speckle noise and multiple interference noise on transparent polymer materials. Microgrooves (nominal width = 300 nm, Rayleigh Criterion of measurement system = 772 nm) on a transparent polymer surface (thermoplastic COC 5013L molded sample) were measured, and the results were compared with AFM measurements. It is demonstrated that the proposed method is instrumental in evaluating the depth of microgrooves beyond the diffraction limit with an accuracy of less than 10% of the test depth. • A novel optical method to achieve the depth measurement of diffraction-limited microgrooves. • Low-coherence illumination to obtain speckle-free images. • Elimination of the multiple interference noise on transparent polymer materials. • Greatly improved accuracy of depth measurement over conventional interferometry. • Evaluation of individual differences for each microgroove, which is not possible with scatterometry. [ABSTRACT FROM AUTHOR]

• Sheltered natural carbonation can be similar between different climates. • Huge impact of curing on natural carbonation for very early age (i.e. 1 day) • Impact of curing is negligible for advanced curing age, regardless of cement type. • Strong impact of precipitation on natural carbonation. • The higher the number of rainy days, the lower the carbonation speed. This paper describes a unique international inter-laboratory study on the carbonation resistance of concrete prepared with different supplementary cementing materials. Concrete specimens – from 45 different concrete mixtures – prepared centrally in Lafarge Centre de Recherche (France) were shipped in a sealed condition to 4 other academia research laboratories (located in USA, Canada, India and China). The specimens were exposed to the ambient environments and atmospheric CO2 concentrations in the five locations, including Lafarge Centre de Recherche in France, in both sheltered and unsheltered condition for a period of 5 years. Measurements of carbonation depth were performed at periodic intervals, and the data was analyzed to assess the influence of climatic conditions on the resistance to carbonation. The results indicate that the general trend of carbonation is not much different irrespective of the macroclimate. Further, the number of rainy days seems to have a more significant influence on the progress of carbonation than the total rainfall in the region. [ABSTRACT FROM AUTHOR]

In standard point-based methods, the depth measurements of the point features suffer from noise, which will lead to incorrect global structure of the environment. This paper presents a submap joining based SLAM with an RGB-D camera by introducing planes as well as points as features.This work is consisted of two steps: submap building and submap joining. Several adjacent keyframes, with the corresponding small patches, visual feature points, and planes observed from these keyframes, are used to build a submap. We fuse the submaps into a global map in a sequential fashion, such that, the global structure is recovered gradually through plane feature associations and optimization. We also show that the proposed algorithm can handle plane association problem incrementally in submap level, as the plane covariance can be obtained in each submap. The use of submap significantly reduces the computational cost during the optimization process, while keeping all information about planes. The proposed method is validated using both publicly available RGB-D benchmarks and datasets collected by authors. The algorithm can produce accurate trajectories and high quality 3D models on these challenging datasets, which are difficult for existing RGB-D SLAM or SFM algorithms. • The proposed algorithm takes advantage of planes in structured indoor scenes, thus can be used to build a high-quality 3D model. • The algorithm is very efficient as it applied submap joining technique, which restricts the most computation extensive part within each local submap. • A novel and effective plane parameterization is formulated on manifold showing better convergence properties in the experiments. • The submap based plane association provides a novel way of associate planes in an incremental fashion. [ABSTRACT FROM AUTHOR]

Large-Scale Particle Image Velocimetry (LSPIV) has emerged as a reliable technology to measure river surface flow velocity distribution and can be applied to estimate river discharge. Fewer studies have explored the capability of surface turbulence measurements using LSPIV. In this paper, LSPIV is applied to evaluate statistics of surface turbulence of a natural river. Turbulence measurements including velocity fluctuation, velocity spectra and the dissipation rate of turbulent kinetic energy (TKE) are validated by comparing with those measured by an Acoustic Doppler Velocimeter (ADV). Traditionally, estimation of stream discharge through LSPIV needs a secondary measurement to determine river bathymetry and water depth. A new method is presented here to demonstrate that for a fully developed and channel-controlled flow, the cross section geometry can be estimated from the combined measurements of surface mean velocity and the dissipation rate, following the Manning-Strickler formula. Therefore, river discharge can be estimated with LSPIV along with a calibrated Manning's roughness, without additional bathymetry survey. The proposed new method is applied to measure discharge in Milwaukee River (Milwaukee, Wisconsin, U.S.A.), which agreed well with data obtained from a nearby streamgage station. • LSPIV is applied to measure surface turbulence structures in a natural river. • Surface turbulence velocity spectra demonstrated a −5/3 power law. • River depth can be estimated from surface turbulence measured by LSPIV. • River discharge can be measured by LSPIV without channel geometry survey. [ABSTRACT FROM AUTHOR]

Abstract A large body of literature exists on the morphology of the Tyrrhenian Sea, the youngest back-arc basin of the Eastern Mediterranean; however, most of these studies are focused on local areas, without considering the broad regional setting. In this paper we consider the morphology of the entire Tyrrhenian Sea at a regional scale, based on a DEM analysis of middle-resolution bathymetry downloaded from the EMODnet website. Based on these data, a first morpholineaments map has been created identifying >500 features >10 km in length, without considering their tectonic settings and age. Furthermore, a Tyrrhenian regional tectonic map has been digitized from literature and the faults divided in Pre-Pliocene, Pliocene and Plio-Quaternary. Morpholineaments and tectonic lineaments have been grouped in six Tyrrhenian Sea areas plotted in rose diagrams in order to obtain the main trends in each region and to detect relationships between morphology and tectonics. Rose diagrams show that most of the identified morpholineaments have a tectonic origin, although they are not coeval, as they developed during different phases of the opening of the Tyrrhenian back-arc basin. Moreover, morpholineaments data suggest that some regions of the Tyrrhenian Sea may be dominated by a single main trend, whereas in other regions the occurrence of more trends testifies a major tectonic complexity. Highlights • A bathymetric map of the entire Tyrrhenian Sea has been created using EMODnet data. • A DEM analysis at regional scale created a morphological lineaments map. • Most of the morpholineaments have a tectonic origin, although they are not coeval. • Results provide good morphostructural patterns of large areas. [ABSTRACT FROM AUTHOR]

Accurate distortion correction is especially crucial for applications involving quantitative measurements such as on-orbit geometric positioning of remoting sensing cameras, depth measurement from stereoscopy, and target tracking and recognition from images. However, the conventional complicated correction methods and the unsatisfied results greatly limit their application prospects, especially in the aerospace field. In this paper, we propose an improved distortion correction method (IDCM) for large aperture infrared tracking cameras, addressing the distortion model and the principle point and distance with high-precision measurement points in the focal plane. Experimental results showed that the distortion errors corrected by the proposed method were 0.26 pixels in a near-infrared image and 0.19 pixels in a short-wavelength infrared image. These corrected distortion errors are better than that corrected by the two-dimensional Lagrange interpolation method (TDLIM) of 0.36 pixels in a near-infrared image and 0.29 pixels in a short-wavelength infrared image, and the conventional distortion model (CDM) of 0.54 pixels in a near-infrared image and 0.64 pixels in a short-wavelength infrared image, respectively. [ABSTRACT FROM AUTHOR]

Abstract Embayed beaches play an important role in ensuring the environmental and morphological sustenance of coastal areas. Coastal processes along embayed beaches are different from that of open beaches. Shoreline management along embayed beaches is a major concern for engineers and policy makers worldwide, which requires a clear understanding of shoreline evolution. As shoreline evolution is the combined effect of natural and human activities, which vary over space and time, numerical models are vital to understanding shoreline change behaviour. The present study was carried out at Vengurla, an embayed beach along the west coast of India, using a well established numerical model. Wave climate, bathymetry, sediment characteristics and initial coastline were the primary inputs for the model. Nearshore wave climate at a depth of 15 m was collected using a wave rider buoy for the year 2015. Bathymetry and nearshore sediments were also collected during the same year. The initial coastline was extracted from satellite imagery of the year 2015. Shoreline change was studied over the preceding 26 years (1990–2016) using nine different satellite images. The model was then run for the following 26 years (2015–40), with present wave climate and future expected increase in wave heights. The results indicate that Vengurla embayed beach is not only affected by various anthropogenic modifications including the destruction of sand dunes, but also by future climate-change projections. We propose the implementation of a dune based shoreline management plan with strict regulations and awareness program. The findings of this study will interest policy makers and environmental managers, guiding them in developing management strategies for protection of this embayed beach. Overall, this paper demonstrates how numerical modelling can help in designing the shoreline management plan for an embayed beach, which can lead to save costs and to prevent further destruction of the beach. Highlights • Shoreline management for embayed beaches is a concern for policy makers and demands proper knowledge of shoreline changes. • Shoreline evolution was investigated using numerical model in the embayed beach of Vengurla, west coast of India. • Shoreline changes were predicted for 26 years using existing wave conditions and future climate scenarios. • We propose a shoreline management plan with extensive dune care, strict regulations and awareness program to be implemented. [ABSTRACT FROM AUTHOR]

Abstract Barrier beach change in directionally bi-modal wave climates presents an increasing challenge for coastal communities, both in the short-term (storm events), and decadal to centurial time scales (long-term evolution). Predicting and planning for subsequent variations requires understanding of the morphological response to changes in wave energy, along with the atmospheric forces driving the wave climate. In this paper, multi-method topo-bathymetric surveys are used to assess the morphological change of a semi-sheltered gravel barrier (Start Bay, Devon, UK). Total sediment budgets (supra- to sub-tidal), with spatially-varying uncertainty levels, indicate the embayment is closed. One third of total sediment flux occurred in the sub-tidal, establishing the importance of sub-tidal transport for this type of coastline. Our results demonstrate that under the predominance of a given wave direction, rotation first occurs within sub-embayments. Additional sustained and extreme energy levels are then required for full embayment rotation to occur, with significant headland bypassing. In this instance, 6 × 105 m3 of gravel was transported alongshore during a 3-year sustained period of dominant-southerly waves, including a 1:50 year storm season (full-embayment rotation), whilst 3 × 105 m3 was returned during a 2-year period of dominant easterly waves (sub-embayment rotation only). A novel parameter is introduced that predicts beach rotation based on the directional wave balance. In turn, winter wave direction is shown to correlate with a combination of two climate indices. Given adequate predictions of relevant climate indices, these findings constitute the basis of a generalisable method to predict and plan for future beach rotation on similar beaches globally. Highlights • Total sediment budgets are required to account for full embayment rotation. • 33% of total sediment changes occurred in the subtidal under episodic wave events. • Beach rotation is parameterized by the balance of directional wave power. • Decadal changes in winter wave climate are well correlated with beach rotation. • Atmospheric indices may predict beach rotation in bi-directional wave climates. [ABSTRACT FROM AUTHOR]

Abstract Dense shelf waters have been recognised as a key factor in transporting sediment and organic matter across continental slopes; however, the effect of their circulation on continental shelves is still overlooked. The Adriatic Sea is one of the areas in the Mediterranean where dense shelf water forms and flows as a bottom-hugging gravity current along the continental margin. A fraction of this dense water passes beyond the shelf break and flows downslope through cascading, while a large (lighter and faster) portion remains on the shelf, with a principal vein flowing between 80 and 120 m water depth. This paper presents the 3D shape, internal architecture and sediment facies of a variety of large-scale sedimentary features detected on the continental shelf and at the shelf edge, between 50 and 300 m water depth. These features include giant comet marks, large flute-shaped scours, muddy sediment waves, very large dunes with superimposed bedforms, active and relict sand ridges and shelf edge contourites. Both erosional and depositional features show an overall internal geometry and orientation consistent with water masses flowing southward, and are located where flows become accelerated by topographic constraints and deviated by the curvature of the shelf edge. In this study, the morphology and seismic stratigraphic structure of large-scale bedforms are investigated in an effort to place constraints on bedform evolution and preservation, especially as predictive tools for sand resource management, and to bring new evidence of the interaction between unidirectional hydrodynamic processes and seafloor dynamics on the shelf. Highlights • An extensive geophysical and coring survey revealed large-scale bedforms on the southern microtidal Adriatic shelf. • Bedforms formed in marine conditions, their age of deposition was inferred through radiocarbon dating and seismostratigraphy. • Sedimentary features, erosional and depositional, have orientations compatible with unidirectional flows. • Bottom currents, including shelf dense waters, are accelerated by bathymetric highs and shelf edge curvature. • Bedforms are palimpsest or relict depending on their location in respect to the unidirectional flow. [ABSTRACT FROM AUTHOR]

Highlights • A procedure for the optimisation of tidal array size through surrogate modelling is introduced. • Array size is defined by means of two design variables: number of rows and number of turbines per row. • Tidal array is placed in a channel of a multi-inlet costal lagoon with complex feedback mechanisms. • A numerical model is set-up and validated to assess effects of arrays in hydro- and morphodynamics. • Multi-objective optimisation models are formulated considering environmental constraints. Abstract This paper investigates the optimum tidal energy converter array density at a tidal inlet by applying surrogate-based optimisation. The SBO procedure comprises problem formulation, design of experiments, numerical simulations, surrogate model construction and constrained optimisation. This study presents an example for the Faro-Olhão Inlet in the Ria Formosa (Portugal), a potential site for tidal in-stream energy extraction. A 35 kW Evopod™ floating tidal energy converter from Oceanflow Energy Ltd. has been used for array size calculations considering two design variables: (1) number of array rows, and (2) number of tidal energy converter per row. Arrays up to 13 rows with 6–11 tidal energy converters each are studied to assess their impacts on array performance, inlets discharges and bathymetry changes. The analysis identified the positive/negative feedbacks between the two design variables in real case complex flow fields under variable bathymetry and channel morphology. The non-uniformity of tidal currents along the array region causes the variability of the resource in each row, as well as makes it difficult to predict the resultant array configuration interactions. Four different multi-objective optimisation models are formulated subject to a set of performance and environmental constraints. Results from the optimisation models imply that the largest array size that meets the environmental constraints is made of 5 rows with 6 tidal energy converter each and an overall capacity factor of 11.6% resulting in an energy production of 1.01 GWh year−1. On the other hand, a higher energy production (1.20 GWh year−1) is achieved by an optimum array configuration, made of 3 rows with 10 tidal energy converters per row, which maximises power output satisfying environmental and performance restrictions. This optimal configuration permits a good level of energy extraction while having a reduced effect on the hydrodynamic functioning of the multi-inlet system. These results prove the suitability and the potential wide use of the surrogate-based optimisation method to define array characteristics that enhance power production and at the same time respect the environmental surrounding conditions. [ABSTRACT FROM AUTHOR]

This paper portrays the application of Fuzzy Cognitive Maps (FCMs) to elicit expert views on current condition and future scenario of coastal susceptibility to erosion in Bangladesh. The geomorphological characteristic of the coastal area is highly dynamic where land erosion and accretion with different rates are constant phenomena. This research focuses on three coastal zones: western, central and eastern that comprise the entire coastal area of the country. Using ‘Mental Modeler’ software this study quantified experts' judgements on the issue and developed FCMs by way of arranging workshops. At the basis, this study identified 33 factors of susceptibility to erosion for current baseline conditions. Considering future projections of hydro-climatic phenomena, this study accentuated potential factors of susceptibility to erosion for future scenario under three time-slices: near-future (2020), future (2050) and far-future (2080). The results generated from FCMs show that some factors such as sedimentation, soft and unconsolidated soils, shelf bathymetry, funnel shape of the Bay of Bengal, wave action, river discharge, monsoon wind, cyclone and storm surges, excessive monsoon rain, high tidal energy, variations of tidal range and sea level rise are highly influential that yielded higher centrality scores for both current and future susceptibility of the area to erosion. The experts' interpretations demonstrate that the future susceptibility to erosion might be higher in the central zone compared to the western and eastern zones of the coastal area. This is the first time that FCM based approach was applied to evaluate expert views on coastal susceptibility to erosion for the country. This study suggests coastal managers, planners and policymakers to consider the current and future factors of susceptibility of coastal lands for taking specific measures options. This study is also significant from socio-economic and demographic contexts of any densely populated coastal area like Bangladesh. [ABSTRACT FROM AUTHOR]

Abstract: We analyzed the distribution patterns of the galatheid squat lobsters (Crustacea, Decapoda, Galatheidae) of the Pacific Ocean. We used the presence/absence data of 402 species along the continental slope and continental rise (200–2000m) obtained from 54 cruises carried out in areas around the Philippines, Indonesia, Solomon, Vanuatu, New Caledonia, Fiji, Tonga, Wallis and Futuna and French Polynesia. The total number of stations was ca. 3200. We also used published data from other expeditions carried out in the Pacific waters, and from an exhaustive search of ca. 600 papers on the taxonomy and biogeography of Pacific species. We studied the existence of biogeographic provinces using multivariate analyses, and present data on latitudinal and longitudinal patterns of species richness, rate of endemism and the relationship between body sizes with the size of the geographic ranges. Latitudinal species richness along the Western and Eastern Pacific exhibited an increase from higher latitudes towards the Equator. Longitudinal species richness decreased considerably from the Western to the Central Pacific. Size frequency distribution for body size was strongly shifted toward small sizes and endemic species were significantly smaller than non-endemics. This study concludes that a clear separation exists between the moderately poor galatheid fauna of the Eastern Pacific and the rich Western and Central Pacific faunas. Our results also show that the highest numbers of squat lobsters are found in the Coral Sea (Solomon-Vanuatu-New Caledonia islands) and Indo-Malay-Philippines archipelago (IMPA). The distribution of endemism along the Pacific Ocean indicates that there are several major centres of diversity, e.g. Coral Sea, IMPA, New Zealand and French Polynesia. The high proportion of endemism in these areas suggests that they have evolved independently. [Copyright &y& Elsevier]

Summary: Continuous surface of river bathymetry (bed topography) is typically produced by spatial interpolation of discrete point or cross-section data. Several interpolation methods that do not account for spatial trend in river bathymetry produce inaccurate surfaces, thus requiring complex interpolation methods such as anisotropic kriging. Although isotropic methods are unsuitable for interpolating river bathymetry, issues that limit their use remain unaddressed. This paper addresses the issue of effect of spatial trend in river bathymetry on isotropic interpolation methods. It is hypothesized that if the trend is removed from the data before interpolation, the results from isotropic methods should be comparable with anisotropic methods. Data from six river reaches in the United States are used to: (i) interpolate bathymetry data using seven spatial interpolation methods; (ii) separate trend from bathymetry; (iii) interpolate residuals (bathymetry minus trend) by using all seven interpolation methods to get residual surfaces, (iv) add the trend back to residual surfaces; and (v) compare resulting surfaces from (iv) with surfaces created in (i). Quantitative and qualitative comparison of results through root mean square error (RMSE), semi-variograms, and cross-section profiles show that significant improvement (as much as 60% in RMSE) can be accomplished in spatial interpolation of river bathymetry by separating trend from the data. Although this paper provides a new simple way for interpolating river bathymetry by using (otherwise deemed inappropriate) isotropic methods, the choice of trend function and spatial arrangement of discrete bathymetry data play a vital role in successful implementation of the proposed approach. [Copyright &y& Elsevier]

EM-MWD systems transmit downhole data via an information channel composed of drill string and formation, and the formation has a strong attenuation effect on the signal. Signal attenuation in EM wave transmission in the formation limits the application well depth. This paper discusses several commonly used methods to improve the depth of EM-MWD applications, including turbine power supplies, adaptive power outputs, transmitting antenna extensions, and repeater transceivers. Based on both theory and practice, the characteristics of these methods are analyzed. An EM-MWD system in which signals are received from an adjacent well is proposed, and a formula for calculating the receiving voltage for an adjacent well is derived based on a model of this system. According to this formula, the proposed EM-MWD system can greatly increase the receiving voltage, where deeper adjacent wells provide a greater increase in the receiving voltage and a greater maximum transmission depth for the EM-MWD system. In-hole experiments of this EM-MWD system based on signals received from an adjacent well demonstrate that this method can effectively increase the voltage of the received signals on the ground, in agreement with theoretical results. • This paper discusses several methods to improve the depth of EM-MWD applications. • An EM-MWD system in which signals are received from an adjacent well is proposed. • A formula for calculating the receiving voltage of the system is derived. • Experiments demonstrate that this method can effectively increase received voltage. [ABSTRACT FROM AUTHOR]

Abstract: There are a variety of different marine sediment transport processes that affect the evolution of continental shelf profiles. Physically based numerical models make it possible to simulate the evolution of the continental shelf in response to these processes, which may be combined with different magnitudes, frequencies and durations. The basic model that is employed in most numerical simulations is based on conservation of mass and is a moving boundary problem since the river mouth progrades into the receiving basin. The general form of these stratigraphic or seafloor evolution models is a first-order, Exner-type differential equation that is forced by a sediment deposition/erosion function. This latter function depends on which sediment transport processes are modeled and how they are modeled, so it is desirable to have a solution method that works for any such function. This paper presents a general solution method to this type of evolution equation that works for any initial bathymetry and sediment deposition function given as 1D functions of seaward distance. It is based on the Laplace transform. Numerical results often exhibit “equilibrium profile” solutions for a wide variety of different model scenarios. These profiles may be viewed as travelling waves, such that the rate of progradation gives the speed of this wave as it advances into the receiving basin. When realistic initial and boundary conditions are used, profiles are often seen to evolve toward forms that are independent of the initial bathymetry. Although episodic perturbations such as turbidities disrupt these forms, they still serve as attractors for the system dynamics. An application of the solution method presented in this paper also allows the shape of equilibrium profiles and the progradation rate to be determined from a specification of the initial bathymetry and the sediment deposition function. Several illustrative examples are given in closed form. Results are also presented that make it possible to compute the amount of time required for an equilibrium profile to be re-established after a perturbation. [Copyright &y& Elsevier]

This paper presents a theoretical and numerical analysis based on a model of mangrove forests incorporating stems and roots to determine the nearshore wave angle and wave height for one-dimensional (1-D) and two-dimensional (2-D) problems. The shallow water equations are solved using the two-step Lax-Wendroff method. The resulting wave height and wave direction vectors are displayed and analyzed to assess the impact of mangrove effects on various bathymetries, including constant, sloping, and parabolic profiles. This procedure is also applied to actual bathymetric data obtained from the Hatiya channel to analyze the influence of mangrove forests and shoreline geometry on the amplitude and wave directionality of nearshore waves. The obtained numerical results demonstrate that both coastal geometry and vegetation exhibit non-linear characteristics in wave behavior. Furthermore, these factors significantly contribute to the directionality and attenuation of nearshore waves. • Mangrove models studied for nearshore wave angle and height via theoretical and numerical methods. • Wave vectors explore mangrove impact on various bathymetries: constant, sloping, parabolic, real. • Numerical results show nonlinear wave behavior due to coastal geometry and vegetation. [ABSTRACT FROM AUTHOR]

• UAV-captured images were applicable for estimating surface water volume of tufa lake group. • Water area extraction was improved by adding surface elevation to inputs of classification ANN. • Deep bathymetry network underestimated water depths of tufa lakes compared with shallow one. • RGB-E classification network and shallow bathymetry network were the optimum combination. Quantitative acquisition of surface water volume of tufa lake group is significant for protecting the tufa landscapes. Limited by low spatial resolution, satellite remote sensing failed to extract the surface water distribution of small and scattered tufa lakes. In recent years, Unmanned Aerial Vehicle (UAV) remote sensing has been increasingly applied to survey aquatic resources and environments, posing great potential for accurately measuring surface water volume of tufa lake group. In this paper, taking the Shuzheng Lakes in Jiuzhai Valley of China as the study site, we used UAV-captured images and Artificial Neural Network (ANN) models to precisely estimate the surface water volume of the tufa lake group. Digital Surface Model (DSM) and orthomosaic were first generated using aerial triangulation. Next, the two classification networks were trained to separate water from vegetation, and then the water extents of individual tufa lakes were extracted. Subsequently, the water depth map of each tufa lake was retrieved using the transferred shallow and deep bathymetry networks. Lastly, the total surface water volume of tufa lake group was achieved by summing the products of pixel unit area and the water depth of each pixel. As results, the surface water volume of tufa lake group estimated by the optimum model combination was approximately 181,360 m3, and the corresponding R-squared was 0.92. These demonstrated the effectiveness of utilizing UAV-based remote sensing and integrated ANN models to accurately estimate surface water volume of tufa lakes. [ABSTRACT FROM AUTHOR]

• The principle of the absolute hydrostatic leveling system as a means to establish online height datum is proposed. • A non-contact absolute hydrostatic level is designed. • Based on precise measurement of liquid depth, an absolute calibration of the level with an accuracy of 0.031 mm can be achieved. • The validation scheme of AHLS and absolute height accuracy is designed and 2-point AHLS can achieve absolute height with an accuracy of no less than 0.05 mm within a 10 m range. The fourth generation light source HEPS under construction in China demands higher alignment accuracy. However, it is difficult to improve height accuracy based on the overlap method of geometric and tracker leveling. Based on the study of hydrostatic leveling systems for ground settlement monitoring, this paper proposes a new method, Absolute Hydrostatic Leveling System (AHLS), for establishing height datum. The principle of establishing height datum for AHLS is described in detail, and it is emphasized that absolute calibration of the level is crucial for implementing this plan. A set of absolute calibration methods for non-contact absolute hydrostatic level is proposed, including measuring key dimensions of the level and precise measurement of liquid depth. The absolute calibration accuracy reaches 0.031 mm. The height accuracy of validating an AHLS between two points within 10 m using a laser tracker is more than 0.05 mm. The results demonstrate the feasibility of using AHLS to establish absolute height datum with high precision. With this method, the absolute height of each point can be obtained independently without any accumulated errors, allowing the establishment of height datum with high precision on a large scale. This approach can be used in the next generation of accelerator devices and also represents a novel method for achieving high-precision vertical monitoring. [ABSTRACT FROM AUTHOR]

In this paper, to improve the pose measurement accuracy of the Time-of-Flight (ToF) camera for space non-cooperative targets, a pose estimation method based on ORBFPFH Simultaneous Localization and Mapping (SLAM) with effective integration of strength and depth measurement information is proposed. The primary process of the method is as follows: First, a unique ORBFPFH Bag of Words (BoW) model for space targets is trained based on the ToF image dataset of spacecraft; Secondly, the pose of the non-cooperative space target is tracked based on the ORBFPFH feature and optimized using the pose graph; Then, based on the ORBFPFH BoW model, loop closure is detected to reduce the cumulative error. Finally, the proposed method is tested on the ToF image dataset: compared with the advanced ORB-SLAM2 algorithm, the proposed method has a minor translation error and rotation error on the test data, with a mean translation error less than 0.144 m and mean rotation error less than 0.642°. The test results show that the proposed method can improve the pose estimation accuracy of space non-cooperative targets, achieve a better 3D point cloud reconstruction effect, and provide technical support for space applications such as rendezvous and docking of non-cooperative spacecraft. © 2001 Elsevier Science. All rights reserved [ABSTRACT FROM AUTHOR]