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Suspended shellfish aquaculture, utilizing longlines and buoys fixed on the sea surface, is a crucial source of global seafood. However, typhoons, as the most common disasters in coastal regions, can generate massive waves and pose a threat to the safety of suspended aquaculture facilities. Therefore, it is essential to investigate the risk levels associated with suspended aquaculture farms during typhoon waves. The example of a large-scale suspended mussel farm in the East China sea was examined in this study. The wave conditions under extreme wind conditions (25m/s) and different typhoon paths were predicted using the SWAN model and modeled results compared well with the observed wave and wind data. The results indicated that when the center of the east-side typhoon was located at the same latitude as the farm, it will face the highest risk level. However, for the west-side and intermediate sweeping typhoons, the risk level reached highest in the farm, when the typhoon center is lower than the latitude of it. Under the combined effects of wind fetch and topography, the risk level in the southeast farming area of the island is the highest under different wind conditions. The farms to the northwest of the island face a higher risk level during the passage of east-side sweeping typhoons, while the southern farms of the island experience an elevated risk level during the west-side and intermediate sweeping typhoons. It is suggested that farming regions with lower risk levels are more conducive to the cultivation of species with longer culture cycles. Conversely, regions considered at higher risk are more suitable for species with shorter culture cycles. The study affords a reference for the optimization and insurance of suspended aquaculture farms. [ABSTRACT FROM AUTHOR]

Methods for calculating the special function of wave catastrophe B4 and its first derivatives, which describe edge focusing of the caustic-tip type with an edge, are studied. The caustic and ray structures of this singularity are constructed. The characteristic amplitude–phase sections of the special function and its derivatives are calculated. The method of rotation of the integration contour and the method of ordinary differential equations are considered and compared both in terms of accuracy and speed. It is shown that the method of ordinary differential equations works stably in the region of negative values of the first two parameters of the special function, and the method of rotation of the integration contour exhibits stability in the region of positive values. Thus, the approaches are complementary. However, the calculation time for the method of ordinary differential equations is an order of magnitude less than the time for the method of rotation of the integration contour. [ABSTRACT FROM AUTHOR]

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The main factors restricting the mining speed of the working face in Yuenan Coal Mine are the water-rich area of limestone above the coal seam and the internal geological concealed structure. The transparent detection of the working face is carried out by using transient electromagnetic method, radio wave perspective and slot wave seismic geophysical methods. In the process of detection, it is found that the induced voltage received by the secondary wave field of transient electromagnetic method is more sensitive to the area of rich water and low resistance, and the lateral situation of coal seam can be identified by observing the energy attenuation emitted and received by radio wave perspective. The integrated analysis of envelope amplitude, spectrum and dispersion curve of in-seam wave seismic imaging has good effect on identifying fault strike. Through the identification of the comprehensive response characteristics of the abnormal region by the induction factor in the multi-wave field, the plane map is superimposed according to the abnormal area delineated by the multi-source wave field, and a variety of abnormal characteristics are shown synthetically, which can effectively identify the correlation between the water-rich area of the roof of the working face and the internal structural area of the coal seam, and clearly judge the existence of the water channel. The test results show that the geophysical method can find out the internal abnormal area of the mining face and predict in advance, and the combined detection of various geophysical methods can provide a reference basis for similar geological conditions in the future.

The main factors restricting the mining speed of the working face in Yuenan Coal Mine are the water-rich area of limestone above the coal seam and the internal geological concealed structure. The transparent detection of the working face is carried out by using transient electromagnetic method, radio wave perspective and slot wave seismic geophysical methods. In the process of detection, it is found that the induced voltage received by the secondary wave field of transient electromagnetic method is more sensitive to the area of rich water and low resistance, and the lateral situation of coal seam can be identified by observing the energy attenuation emitted and received by radio wave perspective. The integrated analysis of envelope amplitude, spectrum and dispersion curve of in-seam wave seismic imaging has good effect on identifying fault strike. Through the identification of the comprehensive response characteristics of the abnormal region by the induction factor in the multi-wave field, the plane map is superimposed according to the abnormal area delineated by the multi-source wave field, and a variety of abnormal characteristics are shown synthetically, which can effectively identify the correlation between the water-rich area of the roof of the working face and the internal structural area of the coal seam, and clearly judge the existence of the water channel. The test results show that the geophysical method can find out the internal abnormal area of the mining face and predict in advance, and the combined detection of various geophysical methods can provide a reference basis for similar geological conditions in the future. [ABSTRACT FROM AUTHOR]

On the basis of a numerical method for solving direct and inverse problems, a method has been developed for tracking the dynamics of the propagation of a seismohydroacoustic wave field, constructing model seismograms, and estimating the velocity characteristics of the complex geophysical structure of the Baikal rift zone in the area of the Babushkin village (southeastern Baikal) and the Buguldeika village (northwestern Baikal). The choice of the profile for modeling is due to the experimental work performed here by the Institute of Physics of the Earth of the Russian Academy of Sciences, the Institute of Computational Mathematics and Mathematical Geophysics of the Siberian Branch of the Russian Academy of Sciences, and the Institute of Geology of the Siberian Branch of the Russian Academy of Sciences in 2021. The algorithm for solving the direct problem of wave field reconstruction is based on applying the Laguerre integral transform in time and finite-difference approximation in the spatial coordinates. The numerical model of the medium used to calculate the propagation of seismic waves is established taking into account a priori data on the velocity section of the Baikal rift zone obtained by a number of researchers in the region according to the data of deep seismic sounding of the Earth. The results of direct numerical modeling assume the prediction of the complex structure of the wave field and are intended to facilitate its interpretation. As an approach to solving the inverse problem of reconstructing the velocity characteristics of an inhomogeneous medium, a computational grid algorithm based on calculating weighted average velocities in sections of the grid superimposed on the Earth's surface is proposed and tested. By choosing the grid step and the method for approximating the discrete wave travel time curve by cubic splines and taking into account the curvature of the head wave travel time curve in areas with a pronounced inhomogeneity of the medium structure, it is possible to determine the velocity characteristic with an increased accuracy. The consistency of the reconstructed theoretical velocity model of the medium with the model experimentally obtained by the method of deep seismic sounding is shown. [ABSTRACT FROM AUTHOR]

To quantify the effect of a current on the height of a wave’s run-up and overtopping combined with an oblique wave approach, the “FlowDike” hydraulic research project was carried out. Tests were performed on two dike slopes of 1:3 and 1:6. Waves were generated across (perpendicular to) the physical model and also inclined in-plane to the stream axis. Oblique waves were generated both towards and along the flow’s direction. The effect of the current and of the wave direction on the height of the wave run-up and amount of the wave overtopping was expressed by means of a combined correction factor for the wave’s inclination and flow velocity. The results of the research confirmed that the flow velocity had only a small effect.

This paper presents a machine learning approach to localizing a five-peak narrow-band modulated sinusoidal signal excitation source within a composite panel. In particular, the Back Propagation (BP) neural network is used. The idea is to use the arrival time of the first wave packet in a five-peak wave signal to locate their source. Specifically, this paper divides the composite material board into multiple regions, designs 8 receiving points to receive the signal from the excitation source, and finds the region where each source is located. The COMSOL numerical simulation platform is used to build a composite plate model and simulate the propagation of five-peak waves to train and test the machine learning network. Correspondingly, carry out experimental verification and use a scanning laser Doppler vibrometer (SLDV) to build a non-contact experimental platform to obtain the wave field information in the composite material plate. The results show that BP neural networks can learn to map signal features to their sources in both contexts.

The dynamic contact problem of the propagation of plane elastic waves incident from infinity onto the boundary of an elastic half-plane reinforced by an infinite plate of small thickness is studied. Questions related to the dynamic mutual influence of an elastic half-plane with an stringer attached to its boundary are studied. As a physical model for the stringer, a one-dimensional elastic continuum model is taken. The solution of the problem is constructed by direct application of the Fourier transform. Analytical expressions are obtained that represent the distribution of wave components in all parts of the half-plane. [ABSTRACT FROM AUTHOR]

Formulation of the problem. Currently, interest in the foundation as a gas and oil field facility has increased significantly. The low efficiency of oil and gas exploration in the basement rocks is usually explained by the absence of a generally accepted hypothesis about the genesis of oil and gas and as a result of migration and accumulation of hydrocarbons. One of the main factors of accumulation is the presence of decompression zones of the foundation, as potential hydrocarbon traps. The article is devoted to the problem of identifying oil and gas bearing zones of foundation decompression. Analysis of recent research and publications. A number of scientific articles on the composition, age, structure and oil and gas potential of the foundation are analyzed. The first step in identifying decompression zones is to conduct gravimetric and magnetic surveys and apply various techniques to interpret the resulting mathematical model of the wave field pattern in order to localize the sources of its anomalies. Identification of previously unresolved parts of a common problem. In order to save money when conducting prospecting and exploration for oil and gas, the foundation proposes an improvement in the methodology for separating gas-bearing “vaulted” parts of decompression zones. Formation of the purpose of the article. The aim of the work is to establish a seismic pattern of anomalies in the geophysical fields of the base decompression zones. The object of research is the zone of decompression of the foundation on the northern side of the Dnieper-Donets depression. The subject of the study is a seismic drawing of the anomaly of the geophysical field of the gas-bearing zone of decompression of the foundation of the Rozsoshinsk structure. Report of the main material. The article analyzes a few materials to identify areas of base decompaction in various oil and gas regions. It was found that for localization of decompression zones, the Berezkin “singular points” method and the correlation method of separation of geophysical anomalies are most effective. The essence of these methods is a kind of filtering of field anomalies, where against the background of the "structural" factor, one can distinguish the "non-structural factor", i.e. decompression zone. This zone in wave fields (∆g and ∆Т) is fixed by a seismic pattern, where minima are usually fixed over hydrocarbon accumulations in relation to contouring maxima. Based on the results of the application of these methods, the structure-testing ground of the gas-bearing decompression zone is established. As an illustrative example of the successful localization of ∆g and ∆Т, data are presented on modeling the foundation softening zone in one of the oil and gas regions of the northern side of the Dnieper-Donets depression.

The article provides an overview of vibroseismic studies carried out in the Baikal rift zone using LargeScale Research Facilities – a powerful CVO-100 seismic vibrator, installed at the South Baikal geodynamic test site SB RAS. Research is carried out according to several methods focused on different tasks: study of the structure of the Earth’s crust and upper mantle in the BRZ, active vibroseismic monitoring, and verification of velocity models of the Earth’s crust. To study the structure of the Earth’s crust and the upper mantle, there were done the vibrator-generated wavefield recordings at the stationary regional network of seismic stations in the Buryat and Baikal branches of the Federal Research Center of the GS RAS, as well as the experimental studies involving the mobile networks deployment (ICMMG SB RAS, SIPE RAS, GIN SB RAS). The aim of the work is to carry out deep vibroseismic sounding of the Earth’s crust (vibro-DSS) at the junction of the Siberian platform, the BRZ and the Sayan-Baikal folded area. The methodology is based on the study of vibration seismograms with the determination of arrival times of the main groups of waves and their correlation with the velocity models of the Earth’s crust in the BRZ. A CVO-100 vibrator and a regional network of seismic stations are used to carry out active vibroseismic monitoring of the southern part of the BRZ. The active monitoring area is about 500×200 km. During vibroseismic monitoring, there were done thorough studies of seasonal variations of the vibrator-generated wavefield and the development of techniques for spectral correction of seismograms. A seismic vibrator CVO-100 was used to carry out experimental verification of the velocity models of the Earth’s crust, developed based on the BEST and PASSCAL experimental data. The vibrational deep seismic sounding (vibro-DSS) on the Baikal – Ulan Bator profile was carried out by the ICMMG SB RAS, GIN SB RAS and BB FRC GS RAS (Russia) in cooperation with IAG MAN (Mongolia).

Subsurface characterization has always been an interesting issue in Geotechnical and geological engineering, especially when there is a potential risk of subsurface anomalies such as cavities and sinkholes. Due to the low resolution and accuracy of seismic recorded data at higher depths, anomalies identification has become more difficult. In this paper, the effect of various types of seismic source loads such as hammer impact, short-time impact, sinusoidal source and Ricker wavelet with a peak frequency of 100, 50 and 20 Hz is evaluated to identify the subsurface cavities by using the Finite Element Method in Abaqus 6.14 software. In addition, The ability of R and P waves are compared after the filtering the waves to detect cavities at different depths of 2, 6, 10 and 20 m. The results show that the frequency content and peak frequency of source load have a significant effect on the penetration depth and wave field resolution. Furthermore, filtering methods and separating R and P waves could be more helpful to identify the shallow and high depths cavities. Also, Ricker seismic source with a central frequency of 100 Hz, hammer impact and short-time impact indicate suitable results for cavities located at depths of 2, 6 and 10 meters. Whereas, it is difficult to identify the backscattered R waves from the cavity at the depth of 20 meters. However, low-frequency seismic load, such as 20 Hz Ricker source load, provides backscattered R and P waves from the cavity at the depth of 20 m. In general, the acceptable results can be obtained by using a combination of P and R waves and applying seismic load proportional to the depth of identification.

An algorithm for constructing a dynamic analysis during the formation of a wave field of stand for testing turbines and the effect of the frequency interaction of the stand's elements on the measurement of its magnitude is described. The research algorithm involves the use of theoretical solutions of nonlinear wave processes using linear oscillations, refined by experiments. The diagnostic model can determine the technical condition of the stand's elements and also determine the causes of the discrepancies between the calculated and measured turbine power values. To clarify the stiffness coefficients between the stand's elements, a modal analysis was used to obtain the range of their changes depending on the external dynamic load, which made it possible to assess the impact of changes in the frequency interaction conditions on the turbine power measurement at different test modes. The conditions for amplifying the amplitude of oscillations at their eigenfrequencies are obtained, and the value of the possible deviation of the expected power value at its measurement for specific modes of the turbine is calculated. The algorithm allows to estimate the dynamic state of the stand-in different research modes of turbines and give recommendations for reducing the level of frequency interaction. [ABSTRACT FROM AUTHOR]

Formulation of the problem. Currently, interest in the foundation as a gas and oil field facility has increased significantly. The low efficiency of oil and gas exploration in the basement rocks is usually explained by the absence of a generally accepted hypothesis about the genesis of oil and gas and as a result of migration and accumulation of hydrocarbons. One of the main factors of accumulation is the presence of decompression zones of the foundation, as potential hydrocarbon traps. The article is devoted to the problem of identifying oil and gas bearing zones of foundation decompression. Analysis of recent research and publications. A number of scientific articles on the composition, age, structure and oil and gas potential of the foundation are analyzed. The first step in identifying decompression zones is to conduct gravimetric and magnetic surveys and apply various techniques to interpret the resulting mathematical model of the wave field pattern in order to localize the sources of its anomalies. Identification of previously unresolved parts of a common problem. In order to save money when conducting prospecting and exploration for oil and gas, the foundation proposes an improvement in the methodology for separating gas-bearing "vaulted" parts of decompression zones. Formation of the purpose of the article. The aim of the work is to establish a seismic pattern of anomalies in the geophysical fields of the base decompression zones. The object of research is the zone of decompression of the foundation on the northern side of the Dnieper-Donets depression. The subject of the study is a seismic drawing of the anomaly of the geophysical field of the gas-bearing zone of decompression of the foundation of the Rozsoshinsk structure. Report of the main material. The article analyzes a few materials to identify areas of base decompaction in various oil and gas regions. It was found that for localization of decompression zones, the Berezkin "singular points" method and the correlation method of separation of geophysical anomalies are most effective. The essence of these methods is a kind of filtering of field anomalies, where against the background of the "structural" factor, one can distinguish the "non-structural factor", i.e. decompression zone. This zone in wave fields (∆g and ∆Т) is fixed by a seismic pattern, where minima are usually fixed over hydrocarbon accumulations in relation to contouring maxima. Based on the results of the application of these methods, the structure-testing ground of the gas-bearing decompression zone is established. As an illustrative example of the successful localization of ∆g and ∆Т, data are presented on modeling the foundation softening zone in one of the oil and gas regions of the northern side of the Dnieper-Donets depression. [ABSTRACT FROM AUTHOR]

The inclusion drift in a standing sinusoidal fluid-velocity wave at various Reynolds and Strouhal numbers under the action of the viscous force, the virtual mass force, the buoyancy force and Basset force has been investigated. For a given inclusion density, as the standing wave frequency increases, its threshold value, above which the direction of the wave force reverses, is attained sooner or later. For various Reynolds and Strouhal numbers (with and without Basset force), the dependences of the squared threshold drag coefficient on the inclusion density number have been found. These dependences show that with increasing Reynolds and Strouhal numbers the threshold value of the squared drag coefficient decreases markedly. Basset force influence on a threshold value has been investigated. It has been shown, that Basset force influence most on threshold values of low-density inclusions.