scholarly journals A Novel Method to Estimate the Sea State for Recycling Work on the Sea Surface

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Haixu Zhang ◽  
Xiaosu Xu ◽  
Guangcai Wang ◽  
Yongyun Zhu
Keyword(s):  
Input Parameter ◽  
Wave Spectrum ◽  
Simulated Data ◽  
Sea State ◽  
Data Distortion ◽  
Improvement Effect ◽  
Wave Heights ◽  
Novel Method ◽  
Significant Wave Heights ◽  
Marine Exploration

The recycling of marine exploration equipment after it has surfaced is greatly affected by sea state. In order to estimate the sea state in real time, this paper proposes a method for measuring wave elevation, which modifies the integrated results of GNSS/SINS in the up direction by virtual horizontal lines to extract wave fluctuation information. From these wave information, the significant wave heights (SWH) can be calculated as the only input parameter of P-M spectrum, and a series of wave height data can be further simulated. When the GNSS is interrupted due to severe sea state, the simulated data can be integrated with the SINS to deal with the data distortion problem. The simulation results show that the application of wave spectrum in the GNSS intermittent situation has obvious improvement effect and important significance.

An Idealization of Wave Scatter Diagram for Spectral Fatigue Analysis

2009 ◽  
Author(s):  
Min Han Oh ◽  
Ki Myung Lee ◽  
Young Sik Jang
Keyword(s):  
Fatigue Analysis ◽  
Scatter Diagram ◽  
Analysis Method ◽  
Sea State ◽  
Environmental Loads ◽  
Wave Data ◽  
Wave Measurements ◽  
Spectral Models ◽  
Wave Heights ◽  
Significant Wave Heights

A spectral fatigue analysis method is most popularly applied for the detailed design of FPSOs. As the environmental loads at the installation site are directly calculated in the spectral analysis, this method gives the most reliable results although it needs much time-consuming works to fully reflect the environmental loads. As the technology of wave measurements advances, the measured wave data increase. Also their spectral models are very complicated because these include many wave components such as swells and wind seas. Since much time and effort are needed to treat these enormous and complicated wave data for the spectral fatigue analysis, a rational idealization of wave data is definitely required. In this paper, wave scatter diagram at Offshore Nigeria was reviewed and their idealization method was proposed. The influence level of each sea state of the wave scatter diagram was identified considering the fatigue damage levels estimated from the significant wave heights and dominant fatigue load RAOs. The sea states giving small fatigue damages were lumped symmetrically by merging or disregarding while those giving large fatigue damages were kept as original. For the validation of this method, the comparisons of dominant fatigue loads and representative fatigue damages were presented for the idealized wave scatter diagram and the original one. From these comparison works, it was confirmed that the idealized wave scatter diagram gives reliable results with reduced amount of calculation work.

Prediction of Safe Sea-State for Pile Driving

2005 ◽  
Author(s):  
Hamid Bazargan ◽  
Hamid Bahai ◽  
Sirous F. Yasseri ◽  
Farzad Aryana
Keyword(s):  
Pile Driving ◽  
Solution Strategy ◽  
Sea State ◽  
Significant Wave ◽  
Dynamic Analyses ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Oceanographic Data ◽  
Ne Pacific ◽  
Pile Response

In this paper vertical piles have been studied with a view to identifying the range of sea-states suitable for the safe pile driving operation. Pile configuration, including the non-linear foundation and the gap between the pile and the pile sleeve shims have been modeled using the finite elements (FE) analysis facilities within ABAQUS. Dynamic analyses of the system for various sea-states characterized by significant wave heights and mean zero upcrossing periods and modeled as a combination of several wave components, have been performed. Repeating the above procedure can generate a table of safe and unsafe sea-states. If the prediction is repeated N times from which n times proved to be safe, then it can be said that the predicted sea-state is safe with a probability of 100(n/N)%. The significant wave height (Hs) and mean zero upcrossing period (Tz) of a future sea-state of a location in NE Pacific (near 46° N 131° W) were generated using the artificial neural networks (ANNs) already trained for this purpose — the location of US National Oceanographic Data Center (NODC) Buoy 46005 is used in this study. The Hs and Tz of some future sea-states were generated from their corresponding conditional 7-parameter probability density functions (pdf’s) given some information including a number of previously measured Hs’s and Tz’s. The parameters of the pdf’s have been estimated from the outputs of 2 different 7-network sets of trained ANNs. This gives a predicted sea-state for a specific time in future. The methodology explained in this paper can identify all control parameters and offer possible solution strategy. The finding reveals that how slight changes in the design configuration can be beneficially exploited to limit the pile response.

scholarly journals The Wave Heights Distribution of Random Wave Based on Ocean Basin

Kapal ◽  
2020 ◽  
Vol 17 (3) ◽  
pp. 114-122
Author(s):  
Nurman Firdaus ◽  
Baharuddin Ali ◽  
Mochammad Nasir ◽  
M Muryadin
Keyword(s):  
Wave Height ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Ocean Basin ◽  
Distribution Model ◽  
Exceedance Probability ◽  
Random Wave ◽  
Theoretical Spectrum ◽  
Sea State ◽  
Wave Heights

The wave height parameter in ocean waves is one of the important information for a marine structure design. The present paper investigates the results of wave heights distribution from laboratory-generated for single sea state. Data of the random wave time series collected at the ocean basin are analyzed using the wave spectrum and compared with the theoretical spectrum in this study. The random wave data is varied with four sea states consisting of sea states 3, 4, 5 and 6 obtained from laboratory measurements. The parameter conditions of generated sea waves are represented by a value of significant wave height and wave peak period in the range of sea states. The individual wave heights data in each sea state are presented in the form of exceedance probability distribution and the predictions using a linear model. This study aims to estimate the wave heights distribution using the Rayleigh and Weibull distribution model. Furthermore, the accuracy of the wave heights distribution data's prediction results in each sea state has been compared and examined for both models. The applied linear models indicate similar and reasonable estimations on the observed data trends.

High Sea State Linear Seakeeping Applicability Metric

2017 ◽  
Author(s):  
Timothy Smith ◽  
Kevin Silva
Keyword(s):  
Design Space Exploration ◽  
Prediction Method ◽  
Sea State ◽  
Hull Form ◽  
Significant Wave ◽  
Linear Behavior ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Hull Forms ◽  
Nonlinear Seakeeping

Linear seakeeping predictions are attractive for design space exploration and preliminary or simple case motion estimates due to calculation speed and relatively simple input requirements. Linear seakeeping theory is an established prediction method with well-known assumptions. One of these assumptions is the assumption that the motions are small. The validity of this assumption is investigated by comparisons with a body exact nonlinear seakeeping code over a range of significant wave heights. A modern naval destroyer and a generic tumblehome ship are examined over a range of speeds, wave headings, and sea significant wave heights. A comparison between linear and nonlinear seakeeping results for the two hull forms show range of linear behavior for different geometries. A general metric based on relative motion is proposed to quantify the validity of the assumption and indicate up to what point linear seakeeping is appropriate including effect of hull form, speed, and relative wave heading.

DEVELOPMENT AND TESTING OF A WEIR BOOM FOR OIL RECOVERY AT SEA*

1981 ◽  
Vol 1981 (1) ◽  
pp. 643-648 ◽  
Author(s):  
H. B. Wilson
Keyword(s):  
Oil Recovery ◽  
High Rate ◽  
Prototype System ◽  
Test Results ◽  
British Petroleum ◽  
Sea State ◽  
Recovery System ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Petroleum Company

ABSTRACT A combined oil containment and recovery system based on a weir boom principle has been designed and developed for high-rate oil spill recovery at sea. A full-scale research prototype system was tested at the Ixtoc I well blowout site in November 1979 by courtesy of Petroleos Mexicanos. The test results have shown that the system design target, specifically to recover 7,500 tonnes of oil or mousse per day per unit in conditions up to sea state 5, with winds up to force 5 on the Beaufort scale, significant wave heights up to 3 metres, and wave periods in the range of 3 to 12 seconds, is achievable. The work has been carried out by the British Petroleum Company with support from the Norwegian and British Governments.

SIMULATION OF NEARSHORE WAVES AND CURRENTS ALONG SALALAH COAST (OMAN) DURING THE TROPICAL CYCLONE ARB01

2017 ◽  
Author(s):  
AbdAlla M. AbdAlla ◽  
AbdAlla M. AbdAlla ◽  
Abkar A. Iraqi ◽  
Abkar A. Iraqi ◽  
Magdy M. Farag ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Domain Boundary ◽  
Circulation Model ◽  
Shielding Effect ◽  
Strong Current ◽  
Waves And Currents ◽  
Wave Heights ◽  
Nearshore Waves ◽  
Flood Period ◽  
Significant Wave Heights

Sea level and wave data at Salalah coast (Oman) were used to simulate nearshore waves and current during the tropical cyclone ARB01 (9 May2002). STWAVE model (Steady State Spectral Wave) was applied for nearshore wave simulation, while M2D model ((Two-Dimensional Depth Averaged circulation model) was used to simulate nearshore current. The results of simulations (taking into account the mutual effects of both current and waves) showed that: The significant wave heights generally decrease from about 6m at the domain boundary to about 1 m close to the coast. The wave heights during the ebb period were higher than that during the flood period by about 1.5m. Along Salalah coast, higher waves were found along the eastern side of the domain. This is because the shielding effect of breakwater, which protect the western part of the coast from high waves. Relatively Strong current with values up to 1.5 ms-1 were found in the nearshore region during both ebb and flood periods. The M2D model results also showed cyclonic circulations during these periods which help in the renewal of harbor waters. Generally, the model results showed good agreements with observations in the investigated area.

scholarly journals An Analytical Method for Dynamic Wave-Related Errors of Interferometric SAR Ocean Altimetry under Multiple Sea States

2021 ◽  
Vol 13 (5) ◽  
pp. 986
Author(s):  
Yao Chen ◽  
Mo Huang ◽  
Yuanyuan Zhang ◽  
Changyuan Wang ◽  
Tao Duan
Keyword(s):  
Electromagnetic Scattering ◽  
Analytical Method ◽  
Wave Spectrum ◽  
High Accuracy ◽  
Sea State ◽  
Error Budget ◽  
Ocean Topography ◽  
Mean Square Errors ◽  
Dynamic Wave ◽  
Wide Swath

The spaceborne interferometric synthetic aperture radar (InSAR) is expected to measure the sea surface height (SSH) with high accuracy over a wide swath. Since centimeter-level accuracy is required to monitor the ocean sub-mesoscale dynamics, the high accuracy implies that the altimetric errors should be totally understood and strictly controlled. However, for the dynamic waves, they move randomly all the time, and this will lead to significant altimetric errors. This study proposes an analytical method for the dynamic wave-related errors of InSAR SSH measurement based on the wave spectrum and electromagnetic scattering model. Additionally, the mechanisms of the dynamic wave-related errors of InSAR altimetry are analyzed, and the detailed numerical model is derived. The proposed analytical method is validated with NASA’s Surface Water and Ocean Topography (SWOT) project error budget, and the Root-Mean-Square Errors (RMSEs) are in good agreement (0.2486 and 0.2470 cm on a 0.5 km2 grid, respectively). Instead of analysis for a typical project, the proposed method can be applied to different radar parameters under multiple sea states. The RMSEs of Ka-band under low sea state, moderate sea state, and high sea state are 0.2670, 1.3154, and 6.6361 cm, respectively. Moreover, the RMSEs of X-band and Ku-band are also simulated and presented. The experimental results demonstrate that the dynamic wave-related errors of InSAR altimetry are not sensitive to the frequencies but are sensitive to the sea states. The error compensation method is necessary for moderate and higher sea states for centimetric accuracy requirements. This can provide feasible suggestions on system design and error budget for the future interferometric wide-swath altimeter.

scholarly journals Red panda: a novel method for detecting variants in single-cell RNA sequencing

BMC Genomics ◽  
2020 ◽  
Vol 21 (S11) ◽  
Author(s):  
Adam Cornish ◽  
Shrabasti Roychoudhury ◽  
Krishna Sarma ◽  
Suravi Pramanik ◽  
Kishor Bhakat ◽  
...  
Keyword(s):  
Single Cell ◽  
Rna Sequencing ◽  
Articular Chondrocytes ◽  
Genetic Diseases ◽  
Simulated Data ◽  
Single Nucleotide ◽  
Single Cell Rna Sequencing ◽  
Red Panda ◽  
Novel Method ◽  
Rare Cells

Abstract Background Single-cell sequencing enables us to better understand genetic diseases, such as cancer or autoimmune disorders, which are often affected by changes in rare cells. Currently, no existing software is aimed at identifying single nucleotide variations or micro (1-50 bp) insertions and deletions in single-cell RNA sequencing (scRNA-seq) data. Generating high-quality variant data is vital to the study of the aforementioned diseases, among others. Results In this study, we report the design and implementation of Red Panda, a novel method to accurately identify variants in scRNA-seq data. Variants were called on scRNA-seq data from human articular chondrocytes, mouse embryonic fibroblasts (MEFs), and simulated data stemming from the MEF alignments. Red Panda had the highest Positive Predictive Value at 45.0%, while other tools—FreeBayes, GATK HaplotypeCaller, GATK UnifiedGenotyper, Monovar, and Platypus—ranged from 5.8–41.53%. From the simulated data, Red Panda had the highest sensitivity at 72.44%. Conclusions We show that our method provides a novel and improved mechanism to identify variants in scRNA-seq as compared to currently existing software. However, methods for identification of genomic variants using scRNA-seq data can be still improved.

scholarly journals Calibration of Camera and Flash LiDAR System with a Triangular Pyramid Target

2021 ◽  
Vol 11 (2) ◽  
pp. 582
Author(s):  
Zean Bu ◽  
Changku Sun ◽  
Peng Wang ◽  
Hang Dong
Keyword(s):  
Simulated Data ◽  
Real Data ◽  
Calibration Method ◽  
Multiple Sensors ◽  
Triangular Pyramid ◽  
World Coordinate System ◽  
Flash Lidar ◽  
Novel Method ◽  
3D Information ◽  
Incremental Validation

Calibration between multiple sensors is a fundamental procedure for data fusion. To address the problems of large errors and tedious operation, we present a novel method to conduct the calibration between light detection and ranging (LiDAR) and camera. We invent a calibration target, which is an arbitrary triangular pyramid with three chessboard patterns on its three planes. The target contains both 3D information and 2D information, which can be utilized to obtain intrinsic parameters of the camera and extrinsic parameters of the system. In the proposed method, the world coordinate system is established through the triangular pyramid. We extract the equations of triangular pyramid planes to find the relative transformation between two sensors. One capture of camera and LiDAR is sufficient for calibration, and errors are reduced by minimizing the distance between points and planes. Furthermore, the accuracy can be increased by more captures. We carried out experiments on simulated data with varying degrees of noise and numbers of frames. Finally, the calibration results were verified by real data through incremental validation and analyzing the root mean square error (RMSE), demonstrating that our calibration method is robust and provides state-of-the-art performance.

scholarly journals Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network

2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
He Wang ◽  
Jingsong Yang ◽  
Jianhua Zhu ◽  
Lin Ren ◽  
Yahao Liu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Wave Height ◽  
Significant Wave Height ◽  
Incidence Angle ◽  
Ocean Waves ◽  
Global Scale ◽  
Learning Technology ◽  
Sea State ◽  
Significant Wave ◽  
Wave Heights

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.

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