Analysis Of Wave Data Research Articles

Numerical Analysis of Long Period Wave Characteristics in Sea Area Based on Mathematical Probability and Statistics

Yu, M. and Du, H., 2019. Numerical analysis of long period wave characteristics in sea area based on mathematical probability and statistics. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 119–124. Coconut Creek (Florida), ISSN 0749-0208.In order to improve the numerical analysis ability of long period wave characteristics in sea area, a numerical analysis method of long period wave feature in sea area based on mathematical probability statistics is proposed. The big data statistical analysis model of long period wave feature analysis in sea area is constructed, and the feature modeling and probability density feature analysis of long period wave data in sea area are carried out by using fuzzy association rule feature mining method. Combined with the mathematical probability statistical method, the fuzzy regional clustering processing of the long period wave data in the sea area is realized, and the feature quantity of the association rules of the long period wave in the sea area is extracted. The fuzzy clustering of the long period wave in the sea area is carried out by using the fuzzy C means clustering fusion method, and the random probability density distribution characteristic quantity of the long period wave in the sea area is excavated in the data clustering center. Combined with the feature space distributed structure reorganization method, the long period wave data is reorganized in the sea area, and the transmission control and feature numerical analysis optimization of the long period wave data in the sea area are realized. The simulation results show that the numerical analysis of long period wave characteristics in sea area is accurate and the data clustering performance is better, which improves the evaluation ability of long period wave dynamic evolution in sea area.

MAGIC - how MAtter’s extreme phases can be revealed in Gravitational wave observations and in relativistic heavy Ion Collision experiments

Nearly one hundred years after Albert Einstein developed the field equations of general relativity and predicted the existence of gravitational waves, a gravitational wave event from a binary neutron star merger (GW170817) was detected in August 2017 by the LIGO/VIRGO collaboration. During the thereon analysis of the gravitational wave data, the equation of state of elementary matter could be constrained in the regime of high densities/temperatures. Recent simulations show, that the appearance of a hadron to quark phase transition in the interior region of a hybrid star merger remnant might change the overall properties of the merger event and could be detectable in future. On the one hand, 4D-simulations of binary neutron star mergers show that these astrophysical systems represent optimal laboratories to investigate the phase structure of quantum chromodynamics. On the other hand, accelerators like the FAIR facility at GSI Helmholtzzentrum allow one to study the properties of the quark-gluon plasma produced in relativistic collisions of heavy ions. This article combines a survey of recent advancements in two rather distinct fields, which reveal - on first sight - a surprising similarity of both, namely relativistic collisions of nuclei and of neutron star mergers.

Comparison of various methods to extract ringdown frequency from gravitational wave data

The ringdown part of gravitational waves in the final stage of merger of compact objects tells us the nature of strong gravity which can be used for testing the theories of gravity. The ringdown waveform, however, fades out in a very short time with a few cycles, and hence it is challenging for gravitational wave data analysis to extract the ringdown frequency and its damping time scale. We here propose to build up a suite of mock data of gravitational waves to compare the performance of various approaches developed to detect quasi-normal modes from a black hole. In this paper we present our initial results of comparisons of the following five methods; (1) plain matched filtering with ringdown part (MF-R) method, (2) matched filtering with both merger and ringdown parts (MF-MR) method, (3) Hilbert-Huang transformation (HHT) method, (4) autoregressive modeling (AR) method, and (5) neural network (NN) method. After comparing their performance, we discuss our future projects.

Evaluation of Plasma Properties From Chorus Waves Observed at the Generation Region

AbstractIn this study we present an inversion method which provides thermal plasma population parameters from characteristics of chorus emissions only. Our ultimate goal is to apply this method to ground‐based data in order to derive the lower‐energy boundary condition for many radiation belt models. The first step is to test the chorus inversion method on in situ data of the Van Allen Probes in the generation region. The density and thermal velocity of energetic electrons (few kiloelectron volts to 100 keV) are derived from frequency sweep rate and starting frequencies of chorus emissions through analysis of wave data from the Electric and Magnetic Field Instrument Suite and Integrated Science on board the Van Allen Probes. The nonlinear wave growth theory of Omura and Nunn (2011, https://doi.org/10.1029/2010JA016280) serves as the basis for our inversion method, assuming that the triggering wave is originated by the linear cyclotron instability. We present 16 consecutive rising‐tone emissions recorded in the generation region between 11 and 12 UT on 14 November 2012. The results of the inversion are compared with density and thermal velocities (parallel and perpendicular) of energetic electrons derived from the unidirectional flux data of the Helium, Oxygen, Proton, and Electron instrument, showing a good agreement: The normalized root‐mean‐square deviation between the measured and predicted values are less than ∼15%. We found that the theoretical amplitudes are consistent with the measured ones. The relation between linear and nonlinear wave growth agrees with our basic assumption; namely, linear growth is a preceding process of nonlinear wave growth. We analyze electron distributions at the relativistic resonant energy ranges.

Long-Term Evolution of Morphology at Loc An Estuary, Vung Tau, Vietnam

In the last decade, the downdrift coast of the Loc An river mouth, Vung Tau province, Vietnam was subject to severe erosion. This was mainly due to the downdrift migration of the river mouth which had reached in total several kilometers over the past 30 years. This study presents the migration of the Loc An river mouth and the related consequences using long-term satellite images and field data. According to wave data analysis, the waves were separated in two different monsoon seasons, northeast and southwest and the characteristics of these waves in the two seasons are noticeably different. This led to contrary dominant directions of the longshore sediment transport between the two monsoon seasons. The river mouth migrated in the southwest direction around 3000 m in the period from 1979 to 2017 (80 m/year). This migration caused the erosion and the collapsing of the geotextile jetties on the right side of the river mouth. The change rate of the surface area of the updrift sand spit is utilized to estimate the longshore sediment rate which equals the order of 2.0 × 105 m3/year. It was noted that a re-occurrence of the breaching would be very difficult in the future due to the strengthening of the back side of updrift sand spit and the operation of the Song Ray reservoir. The migration caused the two jetties to become obsolete, which were constructed to stabilize the river mouth and ensure a smooth passage for the fishing boats. The primary action would be to remove the jetties, however, if this action proves too difficult to be actualized, immediate action like dredging deposited sediment and closing the gap would need to be taken in order for the jetties to become functional again. Additionally, this study illustrates the usefulness of using satellite images to investigate the long-term evolution of the morphology which is still active and where there is still a large amount of change such as in the river mouth area. This is very useful for the research carried out at this specific place or in the country which has limitations in the field and observed data.

Dynamic Response of the Rocket Body under Seismic Excitation

In order to study the influence of seismic excitation on the rocket body during the propellant injection and launch waiting state of a certain rocket, the dynamic response analysis of the rocket structure was carried out, and the seismic response spectrum analysis and time-history analysis were respectively used to solve the structural dynamic response.SolidWorks was used to establish a simplified three-dimensional model of the rocket body, and ANSYS Workbench was imported to solve the static stress, modal frequency and mode of the rocket. Time-history analysis of El-centro seismic wave data was carried out, and Fourier transform was applied to frequency domain spectrum for seismic response spectrum analysis. Cloud maps of structural equivalent stress, displacement and strain were obtained. After numerical verification, the results show that the rocket meets the safety requirements of seismic resistance, and more research methods are verified for the optimization of the rocket body.

Storm Energy Flux Characterization along the Mediterranean Coast of Andalusia (Spain)

This paper investigates wave climate and storm characteristics along the Mediterranean coast of Andalusia, for the period 1979–2014, by means of the analysis of wave data on four prediction points obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF). Normally, to characterize storms, researchers use the so-called “power index”. In this paper, a different approach was adopted based on the assessment of the wave energy flux of each storm, using a robust definition of sea storm. During the investigated period, a total of 2961 storm events were recorded. They were classified by means of their associated energy flux into five classes, from low- (Class I) to high-energetic (Class V). Each point showed a different behavior in terms of energy, number, and duration of storms. Nine stormy years, i.e., years with a high cumulative energy, were recorded in 1980, 1983, 1990, 1992, 1995, 2001, 2008, 2010, and 2013.

Efficient effective one body time-domain gravitational waveforms

Computationally efficient waveforms are of central importance for gravitational wave data analysis of inspiralling and coalescing compact binaries. We show that the post-adiabatic (PA) approximation to the effective-one-body (EOB) description of the binary dynamics, when pushed to high-order, allows one to accurately and efficiently compute the waveform of coalescing binary neutron stars (BNSs) or black holes (BBHs) up to a few orbits before merger. This is accomplished bypassing the usual need of numerically solving the relative EOB dynamics described by a set of ordinary differential equations (ODEs). Under the assumption that radiation reaction is small, the Hamilton's equations for the momenta can be solved {\it analytically} for given values of the relative separation. Time and orbital phase are then recovered by simple numerical quadratures. For the least-adiabatic BBH case, equal-mass, quasi-extremal spins anti-aligned with the orbital angular momentum, 6PA/8PA orders are able to generate waveforms that accumulate less than $10^{-3}$ rad of phase difference with respect to the complete EOB ones up to $\sim 3$ orbits before merger. Analogous results hold for BNSs. The PA waveform generation is extremely efficient: for a standard BNS system from 10Hz, a nonoptimized Matlab implementation of the TEOBResumS EOB model in the PA approximation is more than 100 times faster ($\sim 0.09$ sec) than the corresponding $C^{++}$ code based on a standard ODE solver. Once optimized further, our approach will allow to: (i) avoid the use of the fast, but often inaccurate, post-Newtonian inspiral waveforms, drastically reducing the impact of systematics due to inspiral waveform modelling; (ii) alleviate the need of constructing EOB waveform surrogates to be used in parameter estimation codes.

Characteristics of beach erosion in headland bays due to wave action: Taking the Narrabeen beach in Australia as an example

The special cape-shaped topography of a headland sandy bay is the reason its shoreline varies differently than that of a straight-line coast. The Narrabeen embayment is located on the southeastern coastline of Australia approximately 20 km north of Sydney. The enclosed sandy beach is 3.6 km in length and is composed of fine to medium quartz sand overlying sandstone bedrock, with a median sand grain size D50 of 0.3 mm. Due to the prevalence of moderate to high wave energy conditions and the exposure of the central and northern portions of the beach to the prevailing south-southeastern swell waves. The morphodynamic responses of the Narrabeen beach are highly variable and rapid alongshore. The beach state was predominantly influenced by episodic storm events throughout the year when erosion and accretion can occur. This study analyzed measurements of cross-shore profiles of the Narrabeen headland sandy bay from 1997-1998. With reference to an atypical huge-wave event, this paper describes in detail the beach erosion caused by huge-waves and the beach restoration caused by small waves after the huge-wave event. It also details the relationship between shoreline variation and wave parameters (wave height and wave angle). To discuss the regulations and causes of beach rotation, the study selected six huge wave events that occurred in 1990–2000, all of which were followed by over eight months of small waves, and analyzed the alongshore variation. The results show that the morphodynamic responses of the Narrabeen beach are highly variable and rapid alongshore. During the huge wave events, the beach was eroded and the shoreline retreated. In the aftermath, the small waves restored the beach. The difference in the shoreline variation due to small waves exhibits a rotational pattern. Wave height is related to sand volume above mean sea level and sand accumulation was rapid and high after the big nearshore wave events. The Southern Oscillation Index (SOI) is closely related to the variability in the shoreline. Time-lagged cross-correlations between monthly beach shoreline positions and the SOI were calculated to investigate the presence of stronger cross-correlations between the beach shoreline and the SOI; the central profile (profile 4) is the most sensitive to the feedback of SOI change. The small waves after a huge-wave event make beach rotation periodic. Analysis of directional wave data and the SOI suggests that beach change is driven by changes in wave height (power) and a subtle change in wave direction, both of which are positively related to the SOl. The change in the SOI induces changes in the wave angles, which leads to sediment transport. This is the most important factor in beach rotation. These results reconfirm huge-wave and small waves subaerial morphology, in particular, these results confirm that the wave height and angle, which are induced by the SOI after a huge-wave event, are key drivers of alongshore variation in headland sandy bay coastlines. Under small wave conditions, the northern and mid beach profiles have negative correlations with SOI index, while the southern beach profiles have positive correlations with SOI index. This lead to sediment erosion in the north while sediment deposition in the south. And the shoreline thereby shows a rotational pattern. With the variation of the SOI index, the sediment movement changes in each beach profile, and the shorelines rotational pattern shows periodicity.

Spatially Tracking Wave Events in Partitioned Numerical Wave Model Outputs

AbstractNumerical wave models can output partitioned wave parameters at each grid point using a spectral partitioning technique. Because these wave partitions are usually organized according to the magnitude of their wave energy without considering the coherence of wave parameters in space, it can be difficult to observe the spatial distributions of wave field features from these outputs. In this study, an approach for spatially tracking coherent wave events (which means a cluster of partitions originating from the same meteorological event) from partitioned numerical wave model outputs is presented to solve this problem. First, an efficient traverse algorithm applicable for different types of grids, termed breadth-first search, is employed to track wave events using the continuity of wave parameters. Second, to reduce the impact of the garden sprinkler effect on tracking, tracked wave events are merged if their boundary outlines and wave parameters on these boundaries are both in good agreement. Partitioned wave information from the Integrated Ocean Waves for Geophysical and other Applications dataset is used to test the performance of this spatial tracking approach. The test results indicate that this approach is able to capture the primary features of partitioned wave fields, demonstrating its potential for wave data analysis, model verification, and data assimilation.

Development of nondestructive techniques of preliminary soil foundations geotechnical assessment

Introduction. Modern nondestructive techniques of wave analysis can be applied for the rapid preliminary geotechnical soil assessment. One of these techniques is Multichannel Analysis of Surface Waves (MASW) which allows to obtain velocities profile of shear waves and an initial shear modulus for upper section at minimal duration and labor costs. But for soil deformation properties assessment it is required a deformation modulus obtained by means of direct technique of plate load test. The purpose of the performed study is assessment of the correlation between plate load test deformation modulus and initial shear modulus obtained via wave analysis. Materials and methods. Plate load tests were carried out for various plates and moduli of deformation were calculated. Deformation modulus adjustment factors were applied to perform a comparative analysis of different sizes plates at 5000 cm2 plate. Wave analysis was carried out by the active method of MASW. Results. During comparative analysis a correlation coefficient was evaluated for two cases: the deformation modulus was determined strictly according to GOST 20276-2012; deformation modulus was determined for the loading interval 0.050-0.125 MPa. In the first case “correlation coefficient-unit weight” indicative dependence was observed. The regression equations for the both cases was presented. Conclusions. Correlation between two types of tests was performed by results of in-situ tests. The proposed empirical regression equation allows to obtain the value of the deformation modulus on the basis of wave analysis data and to perform rapidly a soil foundation geotechnical assessment for the future construction.

Properties of Neutron stars with hyperon cores in parametrized hydrostatic conditions

Models of neutron stars (NSs) with hyperon cores are constructed with an effective chiral model in mean-field approximation. The hyperon couplings are fixed by reproducing their experimentally determined binding energies. The impact of these couplings on population of different particles and the equation of state (EoS) are studied in this work. The global properties of NSs like gravitational mass, radius, baryonic mass and central density are calculated using parametrized Tolman–Oppenheimer–Volkoff equations (PTOVs) with special emphasis on two effects of pressure — one contributing to total mass density and the other to self-gravity of the star. We find that with PTOV solutions in static conditions, a softer EoS (including hyperons) can also lead to massive stellar configurations of NSs, which are in good agreement with the observed maximum mass bound of [Formula: see text] (PSR J0348-0432). Estimates of [Formula: see text] and [Formula: see text], obtained with the PTOV equations, are consistent with the recent findings of the same from the data analysis of gravitational waves (GW170817) observation.

Probabilistic characterization of two-dimensional soil profile by integrating cone penetration test (CPT) with multi-channel analysis of surface wave (MASW) data

In situ, laboratory, and geophysical tests are currently used in site characterization. These tests explore different parts of a site measuring different engineering properties at different resolutions or scales. The test results are then used to derive a design profile. In traditional approaches, the positions of boundaries between geological units are identified first, and the soil profile is divided into several layers. Constant engineering properties are assigned to each geological unit and the variabilities within each layer are ignored. To take the uncertainties into account, characteristic design values are assigned. There are no commonly accepted guidelines for choosing design values, however, which introduces additional subjective uncertainties. This paper proposes a probabilistic site characterization approach, based on Bayesian statistical methods, that allows a design profile involving uncertainty to be determined automatically. The derived soil profile is not modelled by uniform layers, but by random fields, which can be used directly in probabilistic analysis. The proposed approach is verified by a synthetic example, and further applied to a soft soil test site in Ballina, New South Wales, Australia, and compared with traditional approaches. The results show that by gradually incorporating more data into the Bayesian inversion, the uncertainty in the soil profile is greatly reduced.

Spectral Characteristics of Gravity‐Capillary Waves, With Connections to Wave Growth and Microbreaking

AbstractIn order to improve our understanding of physical air‐sea interaction, it is essential to better describe the short‐scale ocean wave response to wind forcing. This is particularly true for waves which are small enough to evade observation by traditional buoy and point‐based gauge measurements but large enough to appreciably alter the transfer of momentum between atmosphere and ocean. Such waves are restored to equilibrium both by the Earth's gravity and air‐sea surface tension, hence the classification as “gravity‐capillary.” Radar remote sensing techniques depend greatly upon these waves in order to extract useful physical parameters from afar. Despite this importance, field observations of gravity‐capillary wave characteristics are uncommon and results vary from study to study. Furthermore, leading‐edge model wave number spectra generally do not match each other in shape or important spectral parameters. Here we present an extended analysis of short wave data collected via a polarimetric camera aboard Research Platform Floating Instrument Platform in the Santa Barbara Channel. Our wave number saturation spectra show the emergence of a peak in the gravity‐capillary subrange at low wind forcing magnitude (u*~0.045 m/s), consistent with critical wave growth in air side stability theory and previously only observed in the laboratory. Finally, the effects of microbreaking on wave spectral characteristics are discussed.

A Seca de 2013/2014 na Região Sudeste do Brasil

The claim that droughts in the Southeastern Brazil are being caused by deforestation in the Amazon has no scientific basis and does not survive an analysis of the available climate data. The severe drought that affected Southeastern in the years 2013 and 2014 - and caused social adversities due to the lack of water for human consumption particularly in large cities - is due to the natural climate variability and droughts have occurred in the past, even with greater intensity, notably in the 1930s and 1960s, when the deforestation of the Amazon was incipient. The atmospheric humidity for the Southeastern rainfall is not produced in the Amazon. It comes from the Tropical Atlantic, only passes over the Amazon and interacts with the forest. Using a virtual box inscribed from 0o to 12,5oS, 45oW and 75oW, the annual moisture flux divergence for the years 1999 to 2014 is calculated using the Reanalisys data set available at ESRL/PSD/NOAA. The results show that the years 2013 and 2014 presented the largest mean annual flow values exported towards Southeastern Brazil, 2014[3,45x10 8 kg/s] and 2013[3,08x10 8 kg/s] respectively, during the period of this study. Therefore, it is clear that the 2013-2014 severe drought was not caused by the lack of atmospheric moisture flow. In addition, the analyses of vertical velocity Omega and Outgoing Long Wave (OLR) data observed during the austral summer show the presence of a high pressure system over the Region that resulted in an abnormally atmospheric stability particularly in 2014. Though there is a strong solar heating during the summer season, this high pressure system caused the drought since it inhibited convection and development of thunderstorms as well as blocked the frontal system propagating from southern South America, that is a primary dynamic mechanism for most of the regional rainfall in the summer season. One concludes that the drought in the Southeast Region in the years 2013-2014 was not caused by a lack of atmospheric moisture, but the absence of a dynamic mechanism capable of converting into rainfall the moisture flux originating in the Tropical Atlantic.

Characterizing the Great Lakes marine renewable energy resources: Lake Michigan surge and wave characteristics

The Great Lakes, Lakes Superior, Michigan, Huron, Erie and Ontario, are a system of interconnected freshwater lakes located primarily in the upper region of North America and on the Canada–United States border. Lake Michigan, the second largest in volume and the third-largest in surface area among the Great Lakes, is approximately 494 km long and 190 km wide. The historical wave data show that significant wave height can reach up to 6 m both in the northern and southern basins. In addition, the long-term lake level data reveal that storm surges can exceed 1.5 m in Green Bay, one of the shallowest parts of Lake Michigan. This study characterizes the marine renewable power generation resources including storm surge and wave for Lake Michigan. It is shown that an extreme surge event similar to that of January 12, 1975 could contain a total theoretical potential energy of approximately 58 GWh. The analysis of the lake-wide wave data shows that the monthly mean wave power is greater in the central and southern basins. Wave power is highest in October and November, when the monthly mean wave power exceeds 9 kW/m. The monthly mean wave power is the lowest in late spring and during summer, when it becomes as low as 1.5 kW/m. As a result, it is found that there is significant potential marine renewable energy in Lake Michigan that may be suitable for generating meaningful levels of electricity from storm surges by developing artificial ‘lagoons’ in the shallower parts of the lake. This study, which follows the recent work on characterizing the Great Lakes' marine renewable energy resources [1], is the first attempt on characterizing Lake Michigan's marine renewable energy resources.

Trend Cluster Analysis of Wave Data for Renewable Energy

Trend Cluster Analysis of Wave Data for Renewable Energy

Data analysis of massive gravitational waves from gamma ray bursts

We investigate the detectability of massive mode of polarization of Gravitational Waves (GWs) in [Formula: see text] theory of gravity associated with Gamma Ray Bursts (GRBs) sources. We obtain the beam pattern function of Laser Interferometric Gravitational wave Observatory (LIGO) corresponding to the massive polarization of GWs and perform Bayesian analysis to study this polarization. It is found that the massive polarization component with a mass of [Formula: see text][Formula: see text]eV/c2 is too weak to be detected at LIGO with its current configuration.

Gravitational wave sources and data analysis

What we look for affects how we look for it. I summarize current and predicted sources of gravitational waves, how the physics affects the signals, and how the signal morphologies affect analysis techniques. Expecting long and short signals, well modeled signals and unknown signals, means that gravitational waves use a variety of techniques familiar from acoustics, from matched filtering to wavelets and cross-correlation of data streams. These tell us today about black holes, and one day will tell us about neutron stars, cosmic explosions, and perhaps even stranger things.

Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project

Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the VS,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic principles and specific suggestions related to the most common situations. They are primarily targeted to non-expert users approaching surface wave testing, but can be useful to specialists in the field as a general reference. The guidelines are based on the experience gained within the InterPACIFIC project and on the expertise of the participants in acquisition and analysis of surface wave data.