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The traditional neighborhood rough set model has low noise immunity and computational efficiency for mixed data. This paper establishes a local variable-precision neighborhood rough set model with dynamic change of attributes based on matrix theory. Firstly, on the basis of the updating law of local diagonal matrix and transition matrix, the dynamic updating mechanism of approximation under the local variable-precision neighborhood rough set of mixed information system is constructed; secondly, according to this dynamic updating mechanism, a new dynamic algorithm of local variable-precision neighborhood rough set with attribute change is proposed; finally, through the experimental analysis, it can be seen that the proposed dynamic algorithm has a high computational efficiency and a good robustness. [ABSTRACT FROM AUTHOR]

The efficiency of beach recovery during a time of moderate waves following storm waves is closely related to the interaction between dynamics, sediment, and the landform. The existing studies mainly focus on the description of erosion and accretion characteristics, while the response and feedback mechanism of beach berm sediment have not been elucidated. The main controlling factors of recovery efficiency are not clear. In this paper, field observation and the XBeach numerical model are utilized on the sandy beach in Puqian Bay, China, to capture high-frequency cross-shore data during the post-storm recovery period. The variation characteristics and rules of berm elements, including berm ridge height and slope on two sides of the berm ridge, are analyzed. It is observed that the berm constantly changes to adapt to dynamic conditions. Additionally, a correlation between volume change and certain landform parameters is proposed, leading to the identification of a new relationship in wave run-up. The new forum reflects berm influence and considers the berm ridge and berm width. [ABSTRACT FROM AUTHOR]

Variable and complex marine environmental loads combined with wave resistance and the insufficient controllability of large caisson structures pose serious challenges during maritime towing. Cable breakage events are common, and improper behaviors could give rise to a variety of accidents. This work explored the dynamic responses of large caisson structures following towing cable breakage under irregular waves combined with harsh currents. Two types of cable breakage, i.e., main bridle and towing bridle breakage, were taken into account. Four potential wave–current combinations were assumed for each situation according to direction. The obtained results show that drag rope breakage could give rise to lateral shifts in the structure, which can become a serious condition when exposed to angled waves. Additionally, following breakage, significant force fluctuations took place in the remaining intact cables. For main cable breakage, both lateral and backward displacements were observed in the structure, which gradually entered a 'flowing with the wave' state. Furthermore, under the two abovementioned cable breakage conditions, the structure air gap consistently exceeded 2.3 m, ignoring the possibility of a wave slamming event. [ABSTRACT FROM AUTHOR]

In order to solve problems of traditional image denoising methods such as image blur, edge information loss and so on, an image denoising method based on improved simplified pulse coupled neural network was proposed according to characteristics of underground images including uneven luminosity and large noise. Selection of neurons joining strength β was improved, which made β depend on pixel gray value of image, so as to get better denoising effect. At the same time, selection of decay time constant αE of dynamic threshold was improved, which made αE depend on amplification coefficient vE of threshold output, so as to reduce number of parameters of simplified pulse coupled neural network model. The value of vE was selected through experiment. The experiment results show that the method removes salt and pepper noise of underground images more effectively and preserves details of image edge more completely than traditional median filtering and mean filtering.

In this paper, a novel method to construct non-intrusive reduced order model (ROM) is proposed. The method is based on proper orthogonal decomposition and transformer neural network. Proper orthogonal decomposition is used to generate the basis functions of the low-dimensional flow field, and the coefficients are taken as low-dimensional flow field features. Transformer network is used to extract temporal feature relationships from low-dimensional features. Compared with recurrent neural network and convolutional neural network, transformer network can better capture flow dynamics. At online stage, the input temporal flow sequences are calculated in parallel and can effectively reduce online calculation time. The model proposed in this paper has been verified in two scenarios: two-dimensional flow past a cylinder and two-dimensional flow past a building group. Experimental results show that our model can better capture the flowing change details and has higher accuracy. Compared with the ROM based on long short-term memory and temporal convolutional network, the prediction error is reduced by 35% and 60%, and the time cost is reduced by 65% and 60%. Finally, we apply the ROMs to a practical three-dimensional complicated scenario, flow past London South Bank University, and discuss future development of ROMs. [ABSTRACT FROM AUTHOR]

In this paper, a novel reduced order model based on a convolutional auto-encoder with self-attention (SACAE ROM) is proposed. The proposed model is a non-intrusive reduced order model, which uses a convolutional neural network and a long short-term memory network to extract temporal feature relationships from high-fidelity numerical solutions. The self-attention is introduced into the convolutional neural network to enhance the non-local information perception ability of the convolutional neural network and improve the feature extraction ability of the network. The model adopts a joint construction method, which overcomes the problem of propagating error in each process of the model. The model proposed in this paper has been verified on the problem of the flow around a cylinder. The experimental results indicate that the SACAE ROM has higher robustness and accuracy. Compared with the ROM based on a convolutional auto-encoder, the prediction error of the SACAE ROM is reduced by 42.9%. As with other ROMs based on deep neural networks, the SACAE ROM takes a long time to train. To solve this problem, the transfer and generalization ability of the model is studied in this paper. In the experiment, the flow velocity and spoiler of the flow around the cylinder were changed, and the training time of the transfer model was reduced by about 50% to 60%. This result demonstrates that the problem of too long training time can be solved by transfer learning. [ABSTRACT FROM AUTHOR]

Quantifying how tides evolve with coupling between future sea level rise (SLR) and different coastline configurations is imperative for proposing appropriate coastal defense strategies. By using numerical models, we investigated tidal changes and determined a realistic trend of SLR on the Jiangsu coastal area and adjacent sea on the Yellow Sea shelf. A notable decrease in tidal range occurs in the northern shelf, and the tide increases mainly in the southern shelf. Tidal changes are of both signs, while the increase in sea level is unidirectional. Thus, the SLR effect on tide is not additive in all locations. We also explored the nonlinearity and spatial similarity in tidal range in response to the SLR considering uniform SLR scenarios with multiple levels and allowing inundation of the natural coastline. The patterns of change in tide evolution on the study domain remain linear until the SLR exceeds 2.0 m. Simulations and comparisons are further conducted between the responses of hardened and natural shoreline configurations to SLR. Hardened shoreline introduces both local and remote spatial variability in tidal responses. On the regional scale, SLR induces a shift in the tidal system in the offshore region, which controls the net energy flux into the embayment upon the coast. On the local scale, tidal dynamics are mainly a competition between net energy flux and tidal dissipation and are plausibly influenced by tidal reflection, which depends on whether a basin is tidally reflective. Plain Language Summary: China has experienced rapid economic growth and irreversible pressures from sea level rise (SLR) in the eastern coastal region. To provide future coastal defense strategies, we conduct multiple experiments to simulate how tides evolve with future SLR scenarios as well as how tides respond to different coastline configurations. We found that the future SLR can adjust the entire tidal system and control how much tidal energy flows into the local area from the deep ocean. Whether to build up or maintain a seawall for coastal defense depends on local conditions. By preserving the natural coast and removing the impermeable seawall from the radial sand ridges of China, tidal waves become more progressive on the shoals. Key Points: Tidal change remains linear under a 2.0‐m sea level rise within which a large spatial similarity was achieved on the Yellow Sea shelfDisplacement in the amphidromic point on the northern Yellow Sea shelf dominates the tidal range evolution for the Jiangsu coastal areaThe seawall of Jiangsu with SLR enlarges the tidal range where the tide is reflective but functions opposite where the tide is parallel to the coast [ABSTRACT FROM AUTHOR]

Abstract During Hurricane Sandy, wave overtopping occurred along the barrier beach in front of the Rehoboth Bay, one of the Delaware Inland Bays, as indicated by field observations and the morphological profile model CSHORE. CSHORE estimated a total overtopping volume of about 9.7 × 10 7 m 3 which is close to the storm surge-induced water volume entering the bays through the inlet (about 1.3 × 10 8 m 3 ). In this study, we incorporated the wave overtopping result from CSHORE into the nearshore community model, NearCoM-TVD, to investigate the wave overtopping-induced excessive surge (OIS) in the Delaware Inland Bays. With the wave overtopping applied in the flux boundary condition, the model successfully reproduced the high water level measured at the station located in the Rehoboth Bay. Additional numerical experiments for the separate effects of wave forcing and local winds are also carried out. The results show that wave forcing has a minimal effect on the water level inside the bays. The adjustment of local wind forcing does not qualitatively improve the agreement between the model and data. The model with included wave overtopping predicted an excessive surge of about 20 cm in the Rehoboth Bay, agreeing better with the measured data. Finally, the responses of OIS to different overtopping conditions were performed using an idealized model setup. A strong asymmetry, represented by a much longer draining period versus a shorter period of overtopping increase to the OIS peak, was found in the OIS process for a given temporally symmetric time series of overtopping flux. The asymmetric feature is caused by the imbalance between the overtopping flux and the discharge through the inter-connecting channel inside the Inland Bays. Nonlinearity plays an important role in the process of OIS as demonstrated in modeling OIS-tide-surge interaction. Highlights • Modeling of excessive surge induced by wave overtopping in an inlet-bay system. • The wave overtopping-induced water volume is close to the storm surge-induced volume entering the bays through the inlet. • Wave overtopping has a significant influence on storm surge inside the bays. • Nonlinearity plays an important role in the interaction between overtopping-induced surge and tide. [ABSTRACT FROM AUTHOR]

Oscillations within a rectangular harbor of parabolic bottom induced by small-scale landslides are investigated numerically based on Boussinesq-type equations and the results are used to reveal the characteristics of the oscillations generated on this type of bottom profile. Relatively, local and small-scale landslides within the harbor may induce obvious transverse oscillations. The predominant transverse components are those with small mode numbers m and n when the solid slides start moving from the backwall. The augmentation of the velocity of the slides along the parabolic seafloor may shift the amplitudes of the oscillation components to larger values, which corresponds to the physical understandings of the waves generated by landslides. In comparing the oscillations induced by the slides of constant velocity and those accelerated by gravity force with bottom friction, it is observed that the movements accelerated by gravity force may facilitate the development of certain oscillation modes while those with constant velocity may be in favor of others. While the landslides may not act on an isolated point of the bottom but follow a certain trajectory along the harbor, the transverse oscillations induced by landslides are sensitive to their position of departure both in the cross-harbor direction and in the offshore direction. The numerical result of each transverse eigenfrequency is very close to the theoretical prediction and the spatial structure of each mode may also be well captured by the existing analytical solutions based on shallow water equations. Although longitudinal oscillations may not be steadily generated with landslide movements on a parabolic bottom within the harbor, some patterns of several low-mode ones occur and are also sensitive to the initial location and trajectory of the slides. Wavelet spectra are used to analyze their evolutions and comparisons are made with theoretical predictions. [ABSTRACT FROM AUTHOR]

The smoothed particle hydrodynamics (SPH) technique is a mesh-free numerical method that has great potential to be used in the development of the next generation of numerical ocean models. The implementation of open and solid boundary conditions in the SPH method, however, is not as straightforward as the mesh-based numerical methods. Two types of open boundary conditions are considered in this study: the adaptive open boundary condition (AOBC) and Flather's open boundary condition (FOBC). These two open boundary conditions are implemented in the SPH-based shallow-water equation (SWE) circulation model for simulating sea surface elevations and depth-mean currents over a limited area with open boundaries. The performance of these two open boundaries is assessed in four numerical test cases. In comparison with the conventional characteristic open boundary condition, both the AOBC and the FOBC allow perturbations to propagate out more effectively and are easy to implement with the specification of external flow conditions at the model open boundaries. The model results also demonstrate that the AOBC requires an accurate estimation of the phase speed of perturbations and could lead to a small drift in the mean water level. By comparison, the FOBC is computationally more efficient without any model drift. The SPH-based SWE circulation model is also used in simulating the laboratory observations of the 1993 Okushiri Tsunami. The numerical results in this case demonstrate the feasibility and capability of the SPH-based SWE model for simulating free-surface flows in regions with complicated bathymetry and irregular coastline. [ABSTRACT FROM AUTHOR]

Large caissons are extensively applied as deep-water foundations in marine engineering. In fact, caissons are generally prefabricated and transported to project site by wet towing. Motion responses of large caissons and those occurring during the towing process were investigated, and CO2 emissions under various conditions were calculated. These are all considered to ensure towing safety and environmental protection. The caisson resistance coefficient was simulated via Ansys Fluent software. The effects of towrope length, towing speed, and drift depth on the motion responses of caissons under the combined action of wind and wave were evaluated via Ansys AQWA software. Maximum heave value was dominantly affected by rope length and draft depth, and its fluctuation was highly influenced by towing speed and draft depth. However, all of the above mentioned factors had insignificant influences on pitch response. When towing existed, rope tension was rapidly increased from zero to a constant value that depended on towing speed and drift depth. However, the speed of achieving this stable phase depended on the length of the towrope. [ABSTRACT FROM AUTHOR]

In recent years, researchers have focused their attention on the application of sling exercise therapy in stroke rehabilitation,but results have been inconsistent.The aim of this trial was to explore the effectiveness of sling exercise therapy on balance, mobility, activities of daily living, quality of life and shoulder pain in stroke patients compared with routine physiotherapy. A total of 50 stroke inpatients at The First Affiliated Hospital of the University of South China, Hengyang, Hunan,China,were randomly allocated into one of the two groups: the sling exercise therapy(SET) group (n = 25) received this therapy using a suspension device, and the control group (n = 25) participated routine physiotherapy. The interventions in both groups were performed once a day for 30 min, five times per week for four weeks. Measurements were undertaken prior to and after interventions in both groups. The observational indicies included balance function (Berg Balance Scale, BBS), motor function of the upper and lower limbs (Fugl-Meyer Assessment, FMA), daily living ability (Barthel Index, BI), quality of life (Short Form 36, SF-36), and shoulder pain (Visual Analogue Scale, VAS). After therapy, both the SET group and the control group had significant improvements in BBS, FMA, BI and VAS. Sling exercise therapy improved balance ability (△BBS:Z=-2.16, P = 0.031), upper limb motor function (△Fugl- Meyer-upper:Z= -3.88,P = 0.000) and shoulder pain (△VAS:t = 2.64, P = 0.012) more effectively than routine training in stroke patients. Positive changes in quality of life were found in both groups, although the difference between the two groups was not statistically significant. The sling exercise therapy has been shown to be a safe and effective method to improve balance, mobility, activities of daily living, quality of life and shoulder pain in stroke patients. It could be an important therapeutic strategy to promote comprehensive functional recovery post-stroke. [ABSTRACT FROM AUTHOR]

Oscillations within a rectangular harbor of constant slope induced by submerged sliding masses are investigated numerically based on Boussinesq-type equations and results are used to reveal the characteristics of the generated oscillations. The numerical result of each transverse eigenfrequency is very close to the theoretical prediction and the spatial structure of each mode of the oscillations may also be well captured by the existing analytical solutions based on shallow water equations. The investigation shows that relatively small-scale sliding masses whose width is small compared with the harbor width may induce obvious transverse oscillations. The predominant transverse components are those with small mode numbers when the solid slides start moving from the backwall. In comparing the oscillations induced by the slides of constant velocity and those accelerated by gravity force with bottom friction, it is observed that the movements accelerated by gravity force may facilitate the development of very low transverse oscillation modes while those with constant velocity may also be in favor of the higher ones. The augmentation of the sliding velocity along the constant slope may shift the amplitudes of the oscillation components to smaller values, which corresponds to the physical understandings of the waves generated by underwater sliding masses or landslides. While the sliding masses may not act on an isolated point of the bottom but follow a certain trajectory along the harbor, the transverse oscillations induced by them are sensitive to their position of departure in both the cross-harbor direction and the offshore direction. Longitudinal oscillations may be induced by relatively large sliding masses of harbor width on a constant slope within the harbor. Although the longitudinal oscillations may not reach a steady state without forcing terms at the entrance of the harbor, some patterns of several low-mode ones occur and wavelet spectra are used to analyze their evolutions and comparisons are made with theoretical predictions. It is revealed that the longitudinal oscillations are also sensitive to the moving velocity and initial location of the sliding masses. [ABSTRACT FROM AUTHOR]

Oscillations within a rectangular harbor of parabolic bottom induced by water surface disturbances are investigated numerically based on Boussinesq equations and results are used to reveal the characteristics of the oscillations generated by disturbances of this type. The similarities and differences compared with those generated by a movable seafloor are also discussed. Relatively local and small-scale water surface disturbances may induce obvious transverse oscillations with little trace of longitudinal ones. The predominant transverse components are those with small alongshore mode number m and no node in the offshore direction. The augmentation of the rapidity of depth variation of the parabolic bottom may shift the resonant frequencies to larger values. These transverse modes are sensitive to the initial position of water surface disturbances. The spatial structure of each mode is well captured by the existing analytical solution based on shallow water equations. Although longitudinal oscillations may not be steadily generated with water surface disturbances, some patterns of several low-mode ones occur and are also sensitive to the position of the disturbances. Wavelet spectra are used to analyze their evolutions and comparisons are made with theoretical predictions for the three principle longitudinal modes. [ABSTRACT FROM AUTHOR]

Vertical breakwaters are commonly built on the shore, and their existence must influence the character of nearshore dynamics. Analytical solutions based on linear-shallow water equation are derived for edge waves on a convex exponential profile which may be used to idealize the actual bottom profile with a vertical breakwater at the shoreline. The free surface elevation of the edge waves is described using the first kind of the Bessel functions of order ν. The amplitude profiles are similar to those of edge waves on a sloping beach but confined to a narrower offshore domain near the vertical breakwater. The dispersion relationship is derived from the no-flux boundary condition at the vertical breakwater. The wave number is not only related to the frequency but also the water depth at the vertical breakwater and the profile parameter. The group velocity increases rapidly to the maximum value with the increase of frequency, then decreases slowly and finally approaches the classic shallow water wave celerity of the depth at the vertical breakwater. The possible reason for this distinct behavior may be because dynamic characteristics of edge waves are highly dependent on the profile. Moreover, an extensively validated Boussinesq wave model is used to conduct numerical experiments for edge waves induced by surface bumps. The numerical results are consistent with the proposed solutions, confirming the validity of the new analytical solutions. • Analytical solutions of edge waves on a convex exponential profile are derived. • The amplitude profiles are similar to those of edge waves on a sloping beach but confined to a narrower offshore domain. • The group velocity increases rapidly to the maximum and then decreases slowly with the increase of frequency. • Numerical experiments are conducted to validate the proposed analytical solutions. • The study is hoped to improve the understanding of edge waves on a convex exponential profile. [ABSTRACT FROM AUTHOR]