ABSTRACT Coastal erosion processes are often due to inappropriate coastal defense strategies. The construction of infrastructures that interfere with the coastal circulation and the sediment transport along the coast (piers, docks, etc.), the destruction of the dunes and other anthropogenic modifications to the beach, are some of the factors that limit the adaptability of the beach system and amplify the risk of erosion and flooding of the coastal land. Coastal defense interventions have historically been based on the construction of rigid works (seawalls, groins, breakwaters, jetties, etc.), which, while protecting the territory, have often shifted the problem of erosion to the neighboring coasts. The paper will present the contents and the first findings of the research project STIMARE ( Innovative strategies, monitoring and analysis of the coastal erosion risk ), financed by the Italian Ministry of the Environment and the Sea (MATTM), aimed to define strategies for coastal management, based on a strong involvement of the stakeholders, and on the use of innovative or low-costs technologies for coastal monitoring. Methodology is based on data acquisition, numerical modelling, laboratory tests, physical and ecological monitoring. All the information and results will be discussed with the local stakeholders, in order to provide a comprehensive strategy for coastal protection, following the European Marine Strategy framework. The Project involves researchers from two important Universities in Italy (University of Bologna and Politecnico di Bari) and has a strong interdisciplinary approach, involving coastal engineers, urban planners, geologists, ecologists and mechanical engineers. INTRODUCTION In the coastal erosion processes anthropic activities and inappropriate human interventions frequently alter the littoral dynamics governed by natural factors. Several factors limit the adaptability of the coastal system and amplify the risk of erosion and flooding of the land. Among them, the following ones can be mentioned: the urbanization and the intensive use of the territory, which cause the stiffening of the coastal areas, man-made infrastructures (piers, docks etc.) interfering with the natural longshore sediment transport and the drainage basins and the reduction of sediment supply from drainage basins and the destruction of the dune belt. In the past, coastal defense interventions were commonly realized through the construction of rigid works (e.g., artificial reefs, groins and breakwaters), which, while protecting the territory, have often also shifted the problem of coastal erosion to the nearby littorals, creating a ‘domino’ effect.

ABSTRACT In this real case study two data sets of small strain shear modulus G max from laboratory and in-situ measurements are compared. The two data sets are used as inputs to a linear elastic 3D finite element numerical model to estimate the initial lateral pile-soil stiffness. The question of how much the pile deflection curve depends on the different G max derivation methods is discussed throughout the paper. The study reveals a high importance of stratigraphy for this task, and shows that average input stiffness differences up to 20% throughout the profile do not lead to pile deflection changes at the mudline for the discussed regime. INTRODUCTION Recent monitoring of wind turbines supported by monopile foundations shows that the measured fundamental frequencies are higher than the design predictions (Kallehave et al., 2015 and Versteijlen et al., 2014). This may be caused by an underestimation of the soil stiffness at small strain regimes. The total foundation stiffness has to provide structural frequencies in a specified range in order to avoid resonance with the rotor and blade passing frequencies and with the wind and wave loading. Underprediction as well as an overprediction of stiffness can therefore lead to unacceptable structural responses. The current state of the art for designing monopiles is the p-y curve method described in the offshore standard DNV (2014). However, this approach was developed based on full-scale load tests on slender piles with diameters under 1.0 m. Indeed, the standard DNV (2014) recommends validation of p-y-curves for monopile design, for instance by means of finite element modelling (FEM). Several modifications of the p-y-curve methods have been proposed to account for overprediction of soil-pile stiffness under extreme loads and its underestimation under fatigue loads in monopile design (Wiemann et al., 2004; Soerensen et al., 2012; Kallehave et al., 2012; Kirsch et al., 2014;Thieken, 2015). Regardless of the design method, soil-structure responses calculated at different stress regimes are combined into foundation stiffness and damping matrixes, which serve as boundary conditions for the offshore wind turbine structural design and in turn, among others, for the prediction of the natural frequency.

ABSTRACT Research platforms and vessels are crucial in the Arctic Ocean for international society to deepen the understandings of our globe. The vessels should have capability of winter operations and broad variety of missions, through closer international cooperation beyond the nation and nationalism. Ocean Policy Research Foundation (OPRF) organized an ad hoc committee to develop plans for new icebreaking research vessels to be built in future. Two types of them, of high and low ice classes, were chosen for the vessels to be built within a few decades to come. The authors emphasized the high ice class one, and carried out its conceptual design, rather independently from the committee. The paper mainly described its general design, i.e., less technical portion, briefly. INTRODUCTION Japan has strategic national interests in the Antarctic, and the Arctic, except for scientific activities, under the deliberately vague heading of its sustainable development. In the Antarctic, for the mission to support the research stations in the Antarctica, a heavy icebreaker requires to break through the sea ice and to reach the Showa station every January or February. Japanese Antarctic Research Expedition (JARE) has begun in 1957, when established the Showa Station on East Ongul Island in Queen Maud Land, Antarctica, with the support by the Soya, then lighthouse-supply ship, converted into an ice-strengthened research ship. The Fuji, Shirase, and Shirase (2 nd ) at present, succeeded the Soya as the JARE's ship, gradually more powerful against severe ice loads encountered before getting to the Station. During the 1980s, the industry of Japan had enjoyed the design projects for the oil and gas development in the Canadian Beaufort Sea and accumulated considerable experience in designing heavy icebreakers, although only few of them has stepped forward to build. Soon after the projects on the Arctic issues carried out at OPRF in order to advance proposals to the government, for promotion of much larger research activities in the Arctic than before, OPRF organized an ad hoc committee to grasp the scope of a polar icebreaking research vessel, as a movable research station, putting a slightly high priority to the Arctic. The committee debated on the role and possible contributions of Japan to the international society by construction of the icebreaking research vessel, at the time when the vessel enters service, taking account the rapidly changing the climate, ice features and socio-political attitudes of countries in the world to the Arctic environment and the Antarctic one as well. Discussion on the costs, initial, operating and refurbishing ones, took place. Economies of scale that would be achieved for multi-mission capabilities were also analyzed.

Abstract In this study, an air entrainment model based on the turbulence production and laboratory measured air bubble size spectrum is incorporated into a two-dimensional numerical model (NEWFLUME) to investigate the bubble plume dynamics under breaking processes. The model solves the Reynolds equations for turbulent flow fields and employs the volume-of-fluid (VOF) method to track free surfaces. The integral properties of bubble plume are investigated and compared with the experimental data. The void fraction distributions are examined and the relationship between the void fractions and turbulence intensity is discussed. Introduction In the surf zone, wave breaking is important physical process which generates high intensity of turbulence and entrains a large volume of air bubbles. Numerical investigation of turbulent flow dynamics under breaking waves is still of great challenges, especially in the high intensity air bubble region, mainly due to the complex physical process of air entrainment during wave breaking. Experimental investigations of air entrainment and evolution under breaking waves have been widely conducted for many years. Deane and Stokes (2002) measured the bubble size distribution under the laboratory-scale breaking waves. They found that the bubble size density is closely related to the bubble size, bubbles larger and smaller than 1 mm have bubble size density proportional to the bubble radius with power-law of -10/3 and -3/2 respentively. Cox and Shin (2003) carried out laboratory studies on void fraction distributions in the region close to wave breaking point. The results showed that the maximum ensemble-averaged void fractions are up to 15-20% in spilling breaking and a linear relationship exists between the void fraction and turbulence intensity. This linear dependence was also found by Mori and Kakuno (2008) in experimental measurement. Blenkinsopp and Chaplin (2007) investigated the bubble plume and splash-up properties in laboratory. The results suggested that air entrainment and splash generation account for at least 6.5%~14% of the total energy dissipation. Lim et al. (2015) measured the velocities and void fraction under an unsteady plunging breaking in laboratory. They found that the increase of turbulence level and vorticity level are strongly related with the increase of void fractions.

Abstract The continued advancements in wind energy research has led to interest in the development of computationally efficient software that allows for the inclusion of a more complex understanding of the physical processes in the numerical simulations. In this paper a nondimensional field approach is presented and used to investigate the performance of single rotor and multi-rotor wind turbine configurations. The implementation presented involves a two-step process that first creates large datasets of dimensionless coefficients, and then applies those coefficients to variety of turbine configurations. The datasets are developed using the blade element momentum (BEM) method, and the utilization of dimensionless variables has the advantage of minimizing additional detailed computations. The examples presented illustrate the distribution of forces across single and multiple rotor planes. Further, the examples address the simulation of multi-rotor systems modeling a single row of a wind farm consisting of identical or different wind turbine configurations.

Abstract This paper reports on the development of an acoustic sea ice thickness measurement sensor. The development is applying acoustic Non-Destructive-Testing (NDT) techniques to test first year sea ice including significant amounts of enclosed air bubbles. Two single piezoelectric transducers are tightly placed on smoothed sea ice surface to emit and receive acoustic signals. Besides seeing a detectable reflection from the ice-water interface, the receiving signal also shows significant energy being reflected from entrained air bubbles. Based on the assumption of randomly distributed bubbles, the desired reflection from sea ice-seawater interface can be extracted, through sampling the sea-ice in multiple locations.

Abstract This article describes the technologies for improvement of efficiency of ice cover destruction using interference and flexural gravity waves generated by simultaneous movement of several amphibian hovercrafts (AHC). AHCs will move over the ice cover at constant speed, abreast or in single line ahead. Analysis will be performed using equation of small oscillations of floating visco-elastic plate. Specified system of surface pressures q will move over the plate at speed u. Solution of the equation is obtained in integral form. In order to confirm obtained mathematical relations, experimental research has been performed in experimental basin using elastic film and in ice basin on natural ice cover.

Abstract Increasing request of oil & gas resources has brought to the exploitation of fields technically complex and risky due to severe operating conditions, leading to more stringent requirements for linepipes and accessories. A development program was carried out to enlarge the dimensional range of heavy wall (HW) hot induction bends able to meet more stringent requirements. A new steel design based on low-C content was used to improve both toughness and control of maximum hardness of off-line quenched and tempered HW bends for demanding applications. The new steel, with carbon equivalent lower than 0.42%, was suitable to produce X65 bends with thickness up to 52 mm, very good toughness, and maximum hardness below 250 HV 10 .

Abstract Typically, when an appraisal well is drilled, the focus is on collecting data critical to reservoir characterization such as fluid volumes, temperature, pressure, and formation permeability/porosity in order to evaluate the technical feasibility and economic viability of the field. This data is often inadequate to conduct a thorough corrosion and materials related risk assessment, particularly for nontraditional applications, because evaluations like these are typically done much later in the Project timeline. This paper discusses a number of corrosion and materials related Project issues and related opportunities that may improve commercial viability evaluations or more cost effective concept selection for a field. As a result of the identified opportunities, this paper presents a systematic approach to the improved collection and testing of well data during appraisal well testing at a low additional cost, which is highly beneficial to concept selection and lifecycle asset integrity design.

ABSTRACT Nutrients release from the contaminated bottom sediments on the seabed is widely known to be a source of water pollution. In order to improve the sediment quality, sand capping technique had been utilized in several coastal regions in Japan. However, the effectiveness of this technique was seldom questioned due to new deposition on seabed. This study describes the lasting effect of sand capping techniques on nutrient release reduction from contaminated bottom sediments by field experiments at MM21 district in Yokohama Port. From the study, it is found that this effect is maintained but decreasing due to newly accumulated contaminated sediments on clean capping sand.

ABSTRACT Increasing numbers of FOWT (floating offshore wind turbines) are planned in the coming years due to their high potential in massive generation of clean energy from ocean-wind. In the present study, a numerical prediction tool has been used for the fully coupled dynamic analysis of an offshore floating wind turbine system in time domain including aero-loading, blade-rotor dynamics and control, tower elasticity, mooring dynamics, and platform motions so that the influence of partially broken blade on the system's global performance can be assessed. A mono-column tension leg platform (TLP) type FOWT with 5MW turbine is selected as an example. The blades are 62.6m-long LM fiberglass blades, which are properly modified by NREL. The time-domain analysis is carried out with a sudden break of a tip portion of blade in the middle of simulation, and the dynamic responses of FOWT including transient effects are observed. Through this study, it is seen that the imbalance of rotor due to partially broken blade may induce appreciable loads on the entire wind turbine system, including blades, tower, floater, and tethers, especially in high-frequency range. In particular, due to the rotational imbalance with damage, the 1P, 2P, and 3P excitations and responses are more pronounced in the tower and blade dynamics compared to the intact case. The developed technology and numerical tool are readily applicable to the design of new FOWTs regardless of floater types and environments. The present approach can directly be applied to the development of remote structural health monitoring system for future FOWTs in detecting partial component failure by measuring tower or platform responses.

ABSTRACT This work aims to design physical experiments and test a numerical model for investigating surge-like wave impact on urban structures. Flume experiments are being conducted to evaluate the benefit of an embankment-like structure constructed in front of the buildings for hydrodynamic impact reduction. A finite volume Godunov-type hydrodynamic model is improved and tested for calculating surge induced pressures on structures. Validation against an independent laboratory test demonstrates that the model can be applied to reproduce the current laboratory tests and may be used for more general purposes of evaluating surge impact and facilitating practical design.

ABSTRACT: The bubble image velocimetry (BIV) technical was implemented in a large wave basin for the first time to study its feasibility of measuring velocities in a greenwater flow. The greenwater flow was generated by the impingement of a plunging breaking wave onto a horizontal model deck formed by a square plate. A LED panel was used as the deck and the light source of the BIV system. A high speed camera was used to record images for BIV velocity determination. Measurements taken in the large model basin were used to compare with measurements taken in a small wave tank in a laboratory for examining the scale effect. INTRODUCTION The interaction between extreme waves and structures in ocean is of primary concern in the design of offshore structures. Extreme waves can cause greenwater and damage the structures due to huge forces created by wave impingement, runup, and overtopping. With the recent increase in the frequency and severity of hurricanes, greenwater effect on offshore structure has been increased. The greenwater problem has been investigated by researchers for years. Notably, Buchner (1995) conducted scale model tests with a FPSO unit in a laboratory. Hamoudi and Varyani (1998) studied deck wetness events as a function of Froude number and wave height by performing laboratory tests. Shoenberg and Rainey (2002) applied potential flow based boundary integral equation method to simulate greenwater flow by modeling a moving shelf submerged in water. Due to the nonlinear, turbulent, and multiphase nature of the free surface flow, progress in laboratory measurements and numerical simulations on flow kinematics has been quite limited. In recent years imaging based measurement techniques have advanced rapidly to allow detailed flow velocity measurements in laboratory for ocean engineering related studies However, PIV does not work in flows with high aeration such as greenwater flow.

Accurate long wave generation in laboratories is of key interest in the field of coastal engineering. It allows for the study of long wave propagation, near-shore transformation, shoaling, run-up as well as the interaction with elements of urban development near the shoreline. In this context a novel method for the generation of long waves in the laboratory is presented. It bases on the application of high-capacity pipe pumps under the control of a loop-feedback control mechanism. This methodology yields accurate long wave forms which allow for a geophysical-correct representation of prototype tsunami. INTRODUCTION Against the background of many disastrous tsunami incidents such as the Indian Ocean tsunami in 2004 or the Tohoku tsunami in 2011, where thousands of casualties were counted, the understanding of tsunami propagating in deep water has grown rapidly in the last century. Both numerical and physical modeling techniques are applied to study either one part or the complete process of generation, propagation and run-up/surge flow either ocean-wide or in coastal waters. In laboratory-scaled experiments scientists face scaling problems when reproducing measured long wave time series from either moored ships (e.g Mercator Yacht, Thailand, 2004) or tidal gage records. In this context, applying solitary waves instead of prototype time series in physical modeling is a common approach. The generation of solitary waves is straightforward by means of basic wave maker theory (see e.g. Flick and Guza, 1980). Even though this approach covers a wide area of oceanographic and geophysical aspects, near-shore applications and the study of surge flow as well as wave run-up cannot be addressed appropriately. Wave lengths which are attainable in the laboratory are by far too short compared to geophysical length scales, e.g. prototype tsunami waves. Especially the study of time-dependent processes, e.g.

ABSTRACT Increasing numbers of floating offshore wind turbines are planned to be built in the coming years due to their high potential to generate massive amounts of clean energy from ocean-wind. In the present study, a numerical prediction tool has been developed for the coupled dynamic analysis of a FOWT (floating offshore wind turbine) system in time domain including aero-loading, blade-rotor dynamics and control, tower elasticity, mooring dynamics, and platform motions. A mono-column TLP design with 5MW turbine is selected as an example case study. In case of the TLP type floater, it is seen that the interaction between an elastic tower and platform motion is very important in view of shifting natural frequencies and aero-dynamic excitations and damping. Those coupling effects can be clearly identified by comparing the elastic tower results with the rigid tower results. The developed technology and numerical tools are readily applicable to the design of any new FOWTs in any combinations of irregular waves, dynamic winds, and steady currents. INTRODUCTION Wind is the fastest growing clean and renewable energy source. Until recently, most of the wind-farm development has been limited to the land space. However, the on-land wind farms also have many negative features, such as lack of available space, noise restriction, shade, visual pollution, limited accessibility in mountainous areas, community opposition, and regulatory problems. Therefore, many countries in Europe started to build wind turbines in coastal waters, and so far most offshore wind farms have been installed in relatively shallow-water areas less than 40-m depth by using bottom-fixed-type base structures. Recently, several countries started to plan offshore floating wind farms. Although they are considered to be more difficult to design, wind farms in deeper waters are in general less sensitive to space availability, noise restriction, visual pollution, and regulatory problems. They are also exposed to much stronger and steadier wind fields to be more effective.

ABSTRACT: The resonant column device is commonly used in laboratory to determine the dynamic properties of soils. During the resonant column test, a soil specimen is excited under torsional excitation at different frequencies. In this study, the travel times of the shear (S) and the plane (P) waves were measured on Toyoura sand samples at different relative densities with confining pressures and saturation degrees. Factors effecting on the wave velocities of Toyoura sand samples were investigated by comparing the test results. The variations of the P and S waves are discussed in detail on the basis of experimental results. The study showed that to determine the arrival times of the S-waves and Pwaves measured from the soils needs much more laboratory experiments and field test, as well. INTRODUCTION The resonant column has been used to determine the dynamic behavior of soils since 1930's but using resonant column has been popular after 1960's. The resonant column method was firstly used by Ishimoto & Lida in 1937. Then some researchers such as Hall & Richart (1963), Hardin & Black (1968) and etc. studied the device to determine the dynamic properties of soils. After some improvements and modifications, many researchers are commonly using the resonant column device all over the world. During the resonant column test, a soil specimen is excited under torsional excitation at different frequencies. Test data is obtained as a function of the boundary conditions. The velocity of the propagating wave and the degree of the material damping can be derived by measuring the motion. Shear modulus of the sample can also obtain from velocity and the density. Determining of the shear wave velocity Vs in soils is substantial to identify dynamic response and liquefaction potential (Richart et al. 1970, DeAlba and Baldwin 1991).

ABSTRACT: A strategic study was performed to assess present computational solutions for the realistic simulation of offshore wind turbine installations. Three critical issues were identified that make it desirable to implement a new simulation code. Current numerical codes are not efficient enough, there does not exist a convincing implementation of hydrodynamical effects and mooring system dynamics, and it is difficult to extend existing codes with novel approaches. To tackle these issues, a hybrid computational approach is proposed that takes new developments in commodity computer hardware into account. INTRODUCTION Numerical simulation is the main tool with which complicated physical systems can be analyzed. This is especially true with regard to wind turbine installations, which are systems subject to a number of complex forces and nonlinear behaviors. Simulation is not only used for the design and the certification of structures, but also for the purpose of studying specific effects and properties (both in an industrial and academic context), and for optimization tasks. In all these areas of application, a computational solution needs to model and capture all relevant influences and properties of the system under study. Moreover, computer codes should be flexible enough to allow for later modifications, and efficient enough to allow for nontrivial studies, e.g., involving long simulation times or many different parameter settings (Oliveira and Stewart, 2006). Regarding offshore wind turbines, there exist a number of computational codes and simulation environments that have found widespread use (see below for some influential examples). These are almost exclusively based on experience gained with onshore wind turbine simulation, and are now being adapted to encompass the offshore environment. The main challenge here lies in a realistic description of hydrodynamical effects (Cordle, 2010). Especially for floaters with large-volume buoyant members, radiation and diffraction effects contribute significantly, and in a complex geometry-dependent way.

ABSTRACT A university laboratory has been equipped for carrying out ex- periments on sloshing dynamics inside tanks. In a first series of runs the measurement of the sloshing pressure on the walls of a rectangular tank at various filling levels were carried out. For this activity the pressure time histories at some specific loca- tions together with the instantaneous position of the tank were recorded. Furthermore, images of the sloshing events with a high speed video camera, have been acquired in synchronization with the other signals. The design and operation of such a facility involved a number of foreseen activities but also mitigation of least anticipated road blocks. Many of these were resolved on the go. Since the en- tire activity was to be carried out in a university environment part of the equipment was developed in-house. This approach has the advantage of considerable flexibility but on the contrary unforeseen difficulties can arise. This paper aims to report on the problems that were faced during the set-up and operation and suitable solutions that were adopted. Some of the topics reported here have to do with the technological aspects of the measuring chain while others are more related to the physics of the flow. The following issues, were of particular importance: signal conditioning; operation of the pressure transducers; choice of the optimal sampling frequency; synchronization of the signals and the images; testing procedure and order of the operations; data storage and test logging. Introduction Sloshing is one of the subjects that has raised significant interest in the scientific community in the past years. The industrial importance is related to the transport and storage of LNG at sea and in general to the transport of any liquid in containers.

ABSTRACT Torpedo anchors, a cylindrical steel pipe with a conical tip, are used to moor deep-water offshore facilities. This kind of anchoring may be used in both drilling and production offshore activities. In this study, the terminal velocity of torpedo anchor and consequently its drag coefficient were measured in a water-filled tank with 4 m height and 40 cm in diameter. Four torpedo anchors made of steel were tested in thirty two experiments. A high speed video camera was installed close to the tank to record the falling process, and afterwards the desired frames were extracted and processed to measure the velocity of the anchor. The errors in image processing were calculated and reported, which were in an acceptable range. The results revealed that the mass and dimensions of the torpedo anchor had significant influence on the terminal velocity. INTRODUCTION Nowadays, the demand for fossil oil has grown greatly; as a result, the petroleum industry requires more drilling and production units even in water depths higher than 3000 m. The exploration and development of new facilities in such deep depths calls for more efficient and reliable anchoring system. However, the deepwater anchoring systems can be quite costly. This has pushed the oil and gas industry to always seek a simplified anchoring solution, which simplicity relates to effective installation which would reduce cost, time and complexity of operations. The Deep Penetrating Anchor (DPA) or torpedo anchor is a new kind of anchoring system that has many advantages over conventional solutions. It consists of a cylindrical steel pipe with a conical tip which is used to moor deep-water offshore facilities. This kind of anchoring may be used in both drilling activities as it can be easily recovered, and in production offshore projects because it has enough holding power (Fernandes et al., 2006).

Horizontal density changes in the sea have the potential to drive extreme bottom currents. The focus in this paper is on sill overflows of Atlantic water from the Norwegian Trench into Fensfjorden in Western Norway. Fensfjorden is used for routing pipelines to the oil terminal at Mongstad. The paper describes the total study program that was carried out over the past years and outlines the challenges met in establishing a bottom current data basis for pipeline design and integrity management applications. The work included a study of large scale oceanographic and meteorological conditions believed to influence the actual area, field measurements and a thorough evaluation of the current and density data describing the flow system in the fjord and finally an advanced laboratory testing program in a rotating (Coriolis) basin. A theoretical model was set up connecting large scale ocean dynamics and extreme events of bottom current inflows. The model was tested and confirmed as a valid extreme event forecast model. The model is believed to be of considerable value for a variety of future purposes along the actual part of Fensfjorden. The total work is believed to be relevant for similar coastal locations around the globe. INTRODUCTION Sudden increases of near-bottom currents are known to occur in Norwegian fjords, as well as other places around the globe, and must be taken into account in the design of submarine power or communication cables, pipelines and other seabed installations. Causes of these events include suspension and turbidity currents on slopes and horizontal density differences creating sill overflows to closed basins. The focus here will be on sill overflows of Atlantic water from the Norwegian Trench into Fensfjorden in western Norway. The outer part of Fensfjorden has water depths varying between about 250 m at the sill and down to 540 m at a location about 3 km further into the fjord.