bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non Linear Effect on Wave-Induced Loads for Hull Structural Design: Bulk Carrier, Container Carrier, Vehicles Carrier
Authors: Sugimoto Kei , Fukumoto Yusuke , Matsuwaki Junya , Akamatsu Tatsuya , Ashida Shinsaku , Onishi Koeki , Houtani Hidetaka , Oka Masayoshi , Kawabe Hiroshi , Ishibashi Kinya 
Published: December 2020

Abstract
The structural rules of classification societies typically specify various loads corresponding to the most severe sea states which are expected to be encountered by a ship throughout her service life in order to ensure ship structural safety, and these rules also usually define a variety of simplified formulae to aid in the calculation of such loads. In most cases, such formulae have been developed using linear seakeeping codes and linear statistical predictions; such methods, however, do not typically take into account some complex phenomena due to theoretical and methodological limitations. For this reason, the use of values obtained through linear theory alone is often not sufficient to properly evaluate structural strength, and it is, therefore, necessary to consider other things such as non-linear effects and operational effects. Although the structural rules of classification societies normally take into account such effects, most of them generally treat such things simply as either a constant coefficient or as an implicit condition because of the difficulty of expressing such effects mathematically (i.e. as specific formulae) as well as a general lack of prior research related to such effects.
In this paper, the authors present the results of tank tests and numerical calculations carried out in regular and irregular waves using a bulk carrier, a container carrier and a vehicles carrier, and discuss possible ways of improving the non-linear coefficients specified in the IACS Common Structural Rules (CSR) [1]. Load states, including their non-linear effects, were investigated by examining the behavior of ship motions and hydrodynamic pressure. In order to investigate the behavior of pressure in detail, the pressure acting upon the hull surfaces of the target ships was measured at over 300 locations using a FBG sensor, the latest in optical fiber sensor technology [2].
Nonlinear Amplifications in the Air Gap Response of a Deep Draft Semi-Submersible
Authors: Song Anke , Cai Yuanlang , Yang Xiaolong 
Published: December 2020

Abstract
This paper addresses the nonlinear amplifications in the upwelling crests of air gap responses from the wave basin model test of a deep draft semi-submersible in extreme wave condition. Contributions from nonlinear incident waves, vessel motions and wave-body interactions are analyzed separately. Results from the analyses suggest that, nonlinear amplification factors are larger than predictions from second order corrected model for incident and diffracted waves. Low frequency roll and pitch motions will induce larger nonlinear negative vertical motions for points in down-wave area, thus worsen air gap performance. Upwellings are highly related to diffracted wave elevations. Local run-ups due to highly nonlinear wave-body interactions around column walls could result in the nonlinear amplification factors in this area to be up to 230%.
Axial Compression and Collapse Properties of 3D Re-Entrant Hexagonal Auxetic Structures
Authors: Li Pu , Yue Jingxia , Li Xiaobin , Wan Wenchao 
Published: December 2020

Abstract
A three-dimension (3D) re-entrant honeycomb structure which exhibits negative Poisson’s ratio in all three principal directions is modeled from a classical two-dimension (2D) auxetic material. In this work, on the basis of the Castigliano’s second theorem and Timoshenko beam model, the shear deformation and axial deformation of this structure are investigated. And the analytical formulas of the effective modulus and Poisson’s ratio in each principal direction of the honeycomb structure are derived. By comparing the analytical results with the finite element analysis results, the rationality of the formula is verified. Then, the collapse characteristics of honeycomb structures with different mechanical properties under variation impact velocities are studied. The results show that, the deformation of honeycomb structure can be divided into three patterns, “quasi-static” deformation, “transitional” deformation and “local” deformation varied with impact velocities. And due to inertial effect, with the increase of impact velocity, the load-bearing capacity and energy absorption of the structure also increased. In addition to the impact velocity, the cells’ configuration is also a non-negligible factor, and its turns out that the decrease of angle accelerates the deformation state of the honeycomb structure and strengthen the energy-absorption capability after being subjected to impact load.
A Nonlinear Dual Phase Numerical Model to Investigate the Efficiency Response of Varied OWC Chamber Geometries
Authors: Mayon Robert , Ning De-Zhi 
Published: December 2020

Abstract
A three dimensional, fully nonlinear dual phase numerical wave tank model is created using the open source software OpenFOAM. We incorporate a range of varied Oscillating Water Column (OWC) chamber geometries into the model to investigate the influence of chamber shape on the efficiency response of the OWC. The model is validated through comparison with previously published experimentally obtained chamber free surface heights and chamber pressure data sets. A number of simulations are performed over a range of wave periods for each of the chamber geometries investigated. Then, we generate the efficiency response curves for each of the chamber geometries. The results show that the chamber geometry has a significant influence on the OWC efficiency especially in terms of the optimal performance frequency bandwidths. It is observed that the traditional rectangular box shape OWC chamber seems to be the optimal geometry both in terms of maximum efficiency achieved and in terms of the broadest bandwidth to achieve wave energy extraction.
Investigation on Heave Motion and Load Response of a FPSO in Regular Waves by Fully Nonlinear Method
Authors: Wang Jia-Le , Sun Shi-Li , Ren Hui-Long 
Published: December 2020

Abstract
In this paper, the full nonlinear method based on the three-dimensional potential flow theory and the dynamic analysis method of flexible components are combined to simulate the motion and load response of a FPSO in waves. On the boundary of the hull body, the coupled motions are considered in the impenetrable condition. An improved Eulerian method is adopted to trace strongly nonlinear 3-D free surface deformation. In the far field, artificial damping zone is applied to eliminate reflected wave. Rankine source method is adopted to solve the velocity potential in time domain. Hydrodynamic mesh on hull body is generated by using accumulative chord length cubic parameter spline function. After solving Poisson equation, the initial mesh on free surface becomes orthogonal. In each time step, elastic-mesh-technique (EMT) is used to optimize the mesh on free surface. Several auxiliary functions are introduced to decouple the motions and load, and then the fourth-order Runge-Kutta method is adopted to update the numerical model in time domain. For the forces of the mooring system on the hull at each time step, the dynamic equation of the flexible member is established by the dynamic analysis method based on the elastic slender rod mechanical model, and then the equation is discretized into matrix form by the finite element discretization method and solved. The coupled motion of FPSO hull and mooring system in regular waves of various frequencies in various directions is simulated, and the time domain solutions are obtained. RAO of heave motion in each wave direction is given. The load response at the midship section is analyzed.
Possibilities for a Novel Wave Power Generator Using Dielectric Elastomers
Authors: Chiba S. , Waki M. , Jiang C. , Fujita K. 
Published: December 2020

Abstract
As industrialization, worldwide population growth, and improvements in the living standards in developing countries continue, demands for energy, food, and water, likewise surge. This in turn accelerates global warming, and its resultant extreme weather effects. Among the measures proposed to meet the growing energy demands, the use of renewable energy is gaining more and more attention. In particular, wave power generation is attracting a great deal of attention as an effective use of ocean energy. However, current wave generators are large and very expensive relative to their output. Furthermore, they cannot generate power efficiently with wave directivity, small amplitude waves and so on. For these reasons, widespread use is very limited. In order to solve these problems, this paper discusses the possibility of a recently developed wave power generator that uses a newly developed dielectric elastomer (DE) as a new way to harvest renewable energy. We also discuss the technical breakthrough of building a mega power generation system using DEs.
Modeling of a Hydrokinetic Energy Converter With Two Tandem Cylinders in Flow-Induced Oscillations
Authors: Lv Yanfang , Bernitsas Michael M. , Hai Sun 
Published: December 2020

Abstract
Flow Induced Oscillations (FIO) of tandem cylinders can be enhanced to harness hydrokinetic energy by varying the system parameters. In general, the Converter consists of two mass–spring–damper oscillators subjected to transverse FIOs and specifically Vortex Induced Vibrations and galloping. These FIOs are strongly influenced by variations of the inflow velocity, damping, stiffness, mass and in-flow center-to-center spacing L between two tandem cylinders. In turn, those influence the harnessed power and efficiency of the Converter. In previous experiments, the interactions between the cylinders were proven to be beneficial for the synergy of the cylinders. In this paper, modeling of tandem-cylinder converters is studied considering the Converter parameters, aiming at enhancing the cylinder synergy resulting in increased harnessed power by using a backpropagation (BP) neural network. The main conclusions are: (1) The surrogate model is constructed by a BP network using the experimental data to reduce excessive experimentation or computational inaccuracy. The harnessed power at different flow velocities is computed by the present model and is found to be consistent with experimental results not included in the modeling. (2) Increasing the damping ratio (0.20–0.30) of two tandem cylinders is conducive to improve the power efficiency, but has little effect on power harvesting. (3) In galloping, the harnessed power and its corresponding efficiency for the case of L/D = 1.57 perform at a higher level than that of bigger spacing ratios.
A Holistic Method to Enhance the Sustainable Design, Manufacture, Operation, and End-of-Life of Offshore Supply Vessels
Authors: Liang Mincui 
Published: December 2020

Abstract
Nowadays, sustainable development is becoming a worldwide growing concern for the shipping industry. The overall aim of this paper is to develop a holistic method to enhance sustainable design at the design stage of Offshore Supply Vessels. The process and practice of deciding on the alternative hull & structure materials are presented in the case study to verify and validate the method. The technique includes four main parts. Firstly, Life Cycle Sustainability Assessment, which was developed from Life Cycle Assessment, and which has been carried out to analyze the environmental, economic, and social impacts. Secondly, Monetary Valuation is used to convert the results of the Life Cycle Sustainability Assessment. Moreover, Life Cycle Sustainability Costing is used as an accounting tool to aggregate the results from the Monetary Valuation, including environmental cost, economic cost, and social cost. Finally, the results of Life Cycle Sustainability Costing have been analyzed through Sensitivity Analysis to interpret and make sound recommendations. The novelty of this research is the combination of the different methods, as well as its application to Offshore Supply Vessels.
Time Domain Analysis of Single Module Movement of Deep Sea Rights Enforcement Platform
Authors: Yuhan Wang , Hongtao Yuan , Weiwen Kong , Hankun Yang , Huan Zhang 
Published: December 2020

Abstract
Due to its large size, deep sea rights enforcement platform cannot be closed in the dock, so it needs to be dragged to the pre-installed position for module to module connection. Based on the ANSYS AQWA software, a single module finite element model of the platform is established to solve the security problem of the far-reaching maritime rights enforcement platform in the sea. The hydrodynamic coefficient and the transfer function of the motion response are calculated in the frequency domain, and the response spectrum analysis is carried out. It is worth noting that the single module is a trapezoidal asymmetric structure, so the shape influence on the calculation results will be focused on. The results show that the motion response of the single module is greatly influenced by the wave cycle and the wave direction, because the single module of the platform is a trapezoid asymmetric structure, and the hydrodynamic coefficients are different under different incident waves. Through comparison and parameter analysis, the rationality of the single module design and the good motion performance under the actual sea condition are verified.
Development of 3D FE Models for Incremental Forming Process Analysis of UOE Linepipes
Authors: Wen Shuwen , Li Jun , Fan Zhuozhi , Zhang Shu Yan , Zhang Peng , Connelly Martin 
Published: December 2020

Abstract
Three dimensional (3D) FE models have been developed for simulation of the incremental forming processes employed in UOE linepipe manufacturing at Tata Steel Hartlepool 42” Pipe Mill, namely edge crimping (C-press) and pipe expansion (expander). Transitional zone behaviour resulted from both forming operations as previously identified in practice has been revealed, for the first time, by the 3D FE simulations and preliminarily analysed. It was demonstrated that the transitional zone features observed in both edge crimping and pipe expansion were initiated in the plate/pipe feed-in side/area of the dies, and then formed within the working length/face of the forming dies. Detailed examination and analysis of the FE results, in terms of plastic strain and residual stress patterns as well as contact pressure distributions, have shown that the initiation of the transitional zone features was due to the redundant plastic deformation caused by (cantilever) bending in the material feed-in area of the dies mainly along the longitudinal direction. It is therefore believed that minimisation/elimination of such redundant plastic bending effect in the longitudinal direction would lead to minimisation/elimination of the unfavourable deformation features in the so-called transitional zones, which could be achieved through improved die designs and possibly forming process parameter settings.
Research on Position Keeping and Path Following Strategy for the Under-Actuated Waved Glider
Authors: Wang Peng , Tian Xinliang , Zhang Xiantao , Wang Daoyong , Guo Xiaoxian 
Published: December 2020

Abstract
Wave glider is a novel autonomous surface vehicle that uses energy from surface waves for propulsion. However, because it is inherently under-actuated, multi-variable and strong coupled, it is challenging to control the wave glider accurately under the environmental disturbances. In this study, a novel robust position keeping guidance strategy and an advanced path following approach for the under-actuated wave glider based on restricted circle are firstly developed. Furthermore, an 8-DOFs (Degree-of-Freedom) mathematical model for the under-actuated wave glider is adopted, and the position keeping and path following tasks of the wave glider are conducted in simulation. The results demonstrate that the under-actuated wave glider is able to accomplish the position keeping and path following tasks with the proposed strategies.
Deep Convolutional Recurrent Autoencoders for Flow Field Prediction
Authors: Bukka Sandeep R. , Magee Allan Ross , Jaiman Rajeev K. 
Published: December 2020

Abstract
In this paper, an end-to-end nonlinear model reduction methodology is presented based on the convolutional recurrent autoencoder networks. The methodology is developed in the context of overall data-driven reduced order model framework proposed in the paper. The basic idea behind the methodology is to obtain the low dimensional representations via convolutional neural networks and evolve these low dimensional features via recurrent neural networks in time domain. The high dimensional representations are constructed from the evolved low dimensional features via transpose convolutional neural networks. With an unsupervised training strategy, the model serves as an end to end tool which can evolve the flow state of the nonlinear dynamical system. The convolutional recurrent autoencoder network model is applied on the problem of flow past bluff bodies for the first time. To demonstrate the effectiveness of the methodology, two canonical problems namely the flow past plain cylinder and the flow past side-by-side cylinders are explored in this paper. Pressure and velocity fields of the unsteady flow are predicted in future via the convolutional recurrent autoencoder model. The performance of the model is satisfactory for both the problems. Specifically, the multiscale nature and the gap flow dynamics of the side-by-side cylinders are captured by the proposed data-driven model reduction methodology. The error metrics, the normalized squared error and the normalized reconstruction error are considered for the assessment of the data-driven framework.
Materials for Well Integrity: Characterization of Short-Term Mechanical Properties
Authors: Kamali Mohammadreza , Khalifeh Mahmoud , Saasen Arild , Delabroy Laurent 
Published: December 2020

Abstract
Integrated zonal isolation is well-known as a key parameter for safe drilling operation and well completion of oil and gas wells. An extensive research on alternative materials has been conducted in the past concerning primary cementing, overcoming annular leaks, and permanent well abandonment. The present article focuses on geopolymers, expansive cement, pozzolan based sealant and thermosetting resins.
The viscous behavior and the pumpability of the different materials have been investigated and benchmarked with the properties of neat class G Portland cement. The current study includes short-term mechanical properties of the above-mentioned materials. These properties include compressive strength development, Young’s modulus, indirect tensile strength, and sonic strength. The tests are performed in accordance with API 10B-2 and ASTM D3967-16 for all the materials for 1, 3, 5, and 7-day of curing at 90°C and elevated (172 bar) and atmospheric pressures. Our results show a mixed behavior from the materials. According to uniaxial compressive test results, all the candidate barrier materials developed strength during the considered period; however, the geopolymer and pozzolanic-based mixture did not develop early strength. The expansive cement showed an acceptable early compressive strength, but strength reduction was noticed after some time. The strength reduction of expansive cement was also observed for the indirect tensile strength. All the materials become stiffer overtime as they made more strength. For the neat class G cement and expansive cement, the Young’s modulus showed a minimum after 5 days, but it was increased.
A Global Operability Index for an Offshore Vessel
Authors: Mauro Francesco , Nabergoj Radoslav 
Published: December 2020

Abstract
For the operability evaluation of an offshore unit, it is usual to adopt specific working limiting criteria dealing with ship motions and accelerations. These criteria given by operators reflect the ability of the vessel (or crew) to accomplish a precise target in an operative scenario with different meteorological conditions. However, an offshore vessel needs also to keep a determined position and heading during working operations. That means designers or operators have to consider criteria associated both with seakeeping and station keeping to evaluate the effective operability of the vessel. Traditionally, early design stage operability analyses do not combine seakeeping and station keeping predictions, which are referring to different working environments. Here, an innovative procedure allows to evaluate the joint operability of an offshore unit, adopting scatter diagrams for local environmental conditions. The method has been applied on a Pipe-Laying vessel, assessing the global operability for different areas of commercial interest.
Global Hierarchical Models for Wind and Wave Contours: Physical Interpretations of the Dependence Functions
Authors: Haselsteiner Andreas F. , Sander Aljoscha , Ohlendorf Jan-Hendrik , Thoben Klaus-Dieter 
Published: December 2020

Abstract
Applications such as the design of offshore wind turbines requires the estimation of the joint distribution of variables like wind speed, wave height and wave period. The joint distribution can then be used, for example, to define design load cases using the environmental contour method. Often the joint distribution is described using so-called global hierarchical models. In these models, one variable is taken as independent and the other variables are modelled to be conditional on this variable using particular dependence functions. In this paper, we propose to use dependence functions that offer physical interpretation. We define a novel dependence function that describes how the median of the zero-up-crossing period increases with significant wave height and a novel dependence function that describes how the median significant wave height increases with wind speed. These dependence functions allow us to reason about the physical meaning, even when we extrapolate outside the range of a given sample of environmental data. In addition, we can analyze the estimated parameters of the dependence function to speculate which kind of sea dominates at a given site. We fitted statistical models with the proposed dependence functions to six datasets and analyzed the estimated parameters. Then we calculated environmental contours based on these estimated joint distributions. The environmental contours had physically reasonable shapes, even at areas that were outside the datasets that were used to fit the underlying distributions.
Nonlinear Fourier Analysis of Free-Surface Buoy Data Using the Software Library FNFT
Authors: Wahls Sander , Bruehl Markus , Fan Yang-Ming , Huang Ching-Jer 
Published: December 2020

Abstract
Nonlinear Fourier Analysis (NFA) is a powerful tool for the analysis of hydrodynamic processes. The unique capabilities of NFA include, but are not limited to, the detection of hidden solitons and the detection of modulation instability, which are essential for the understanding of nonlinear phenomena such as rogue waves. However, even though NFA has been applied to many interesting problems, it remains a non-standard tool. Recently, an open source software library called FNFT has been released to the public. (FNFT is short for “Fast Nonlinear Fourier Transforms”.) The library in particular contains code for the efficient numerical NFA of hydrodynamic processes that are approximately governed by the nonlinear Schroedinger equation with periodic boundary conditions. Waves in deep water are a prime example for such a process. In this paper, we use FNFT to perform an exemplary NFA of typhoon data collected by wave buoys at the coast of Taiwan. Our goals are a) to demonstrate the application of FNFT in a practical scenario, and b) to compare the results of a NFA to an analysis based on the conventional linear Fourier transform. The exposition is deliberately educational, hopefully enabling others to use FNFT for similar analyses of their own data.