bluuebunny/crossref_metadata_2025 huggingface dataset:
FROM EMBODIED TO EXTENDED COGNITION
Authors: Teske John A.
Published: August 2013

Embodied cognitive science holds that cognitive processes are deeply and inescapably rooted in our bodily interactions with the world. Our finite, contingent, and mortal embodiment may be not only supportive, but in some cases even constitutive of emotions, thoughts, and experiences. My discussion here will work outward from the neuroanatomy and neurophysiology of the brain to a nervous system which extends to the boundaries of the body. It will extend to nonneural aspects of embodiment and even beyond the boundaries of the body to prosthetics of various kinds, including symbioses with a broad array of cultural artifacts, our symbolic niche, and our relationships with other embodied human beings. While cognition may not always be situated, its origins are embedded in temporally and spatially limited activities. Cognitive work also can be off‐loaded to the body and to the environment in service of action, tool use, group cognition, and social coordination. This can blur the boundaries between brain areas, brain and body, and body and environment, transforming our understanding of mind and personhood to provide a different grounding for faith traditions in general, and of the historically dualist Christian tradition in particular.
Developing Compact Models of Terrain Surfaces
Authors: Chemistruck Heather M. , Ferris John B.
Published: August 2013

Terrain topology is the principal source of vertical excitation to the vehicle system and must be accurately represented in order to correctly predict the vehicle response. It is desirable to evaluate vehicle and tire models over a wide range of terrain types, but it is computationally impractical to simulate long distances of every terrain variation. This work seeks to study the terrain surface, rather than the terrain profile, to maximize the information available to the tire model (i.e., wheel path data), yet represent it in a compact form. A method to decompose the terrain surface as a combination of deterministic and stochastic components is presented. If some, or all, of the components of the terrain surface are considered to be stochastic, then the sequence can be modeled as a stochastic process. These stochastic representations of terrain surfaces can then be implemented in tire and vehicle models to predict chassis loads.
Measured Comparison of Leakage and Rotordynamic Characteristics for a Slanted-Tooth and a Straight-Tooth Labyrinth Seal
Authors: Mehta Naitik J. , Childs Dara W.
Published: August 2013

Measured results are presented to compare rotordynamic coefficients and leakage of a slanted-tooth labyrinth seal and a straight-tooth labyrinth seal. Both seals had identical pitch, depth, and number of teeth. The teeth inclination angle of the teeth on the slanted-tooth labyrinth was 65 deg from the normal axis. Experiments were carried out at an inlet pressure of 70 bar-a (1015 psi-a), pressure ratios of 0.4, 0.5, and 0.6, rotor speeds of 10.2, 15.35, and 20.2 krpm, and a radial clearance of 0.2 mm (8 mils). One zero and two positive inlet preswirl ratios were used. The results show only minute difference in the rotordynamic coefficients between the two seals. The slanted-tooth labyrinth seal consistently leaked approximately 10% less at all conditions. Predictions were made using a one control volume bulk-flow model (1CVM) which was developed for a straight-tooth labyrinth seal design. 1CVM under-predicted the rotordynamic coefficients and the leakage.
A Simple Model for Axial Displacement in a Cylindrical Pipe With Internal Shock Loading
Authors: Bitter Neal P. , Shepherd Joseph E.
Published: August 2013

This paper describes a simplified model for predicting the axial displacement, stress, and strain in pipes subjected to internal shock waves. This model involves the neglect of radial and rotary inertia of the pipe, so its predictions represent the spatially averaged or low-pass–filtered response of the tube. The simplified model is developed first by application of the physical principles of conservation of mass and momentum on each side of the shock wave. This model is then reproduced using the mathematical theory of the Green's function, which allows other load and boundary conditions to be more easily incorporated. Comparisons with finite element simulations demonstrate that the simple model adequately captures the tube's axial motion, except near the critical velocity corresponding to the bar wave speed E/ρ. Near this point, the simplified model, despite being an unsteady model, predicts a time-independent resonance, while the finite element model predicts resonance that grows with time.
Modeling and Control of an Automotive All-Wheel Drive Clutch as a Piecewise Affine System
Authors: Duan Shiming , Ni Jun , Ulsoy A. Galip
Published: August 2013

Piecewise affine (PWA) systems belong to a subclass of switched systems and provide good flexibility and traceability for modeling a variety of nonlinear systems. In this paper, application of the PWA system framework to the modeling and control of an automotive all-wheel drive (AWD) clutch system is presented. The open-loop system is first modeled as a PWA system, followed by the design of a piecewise linear (i.e., switched) feedback controller. The stability of the closed-loop system, including model uncertainty and time delays, is examined using linear matrix inequalities based on Lyapunov theory. Finally, the responses of the closed-loop system under step and sine reference signals and temperature disturbance signals are simulated to illustrate the effectiveness of the design.
Sliding and Nonsliding Joint Constraints of B-Spline Plate Elements for Integration With Flexible Multibody Dynamics Simulation
Authors: Mizuno Yuta , Sugiyama Hiroyuki
Published: August 2013

In this investigation, a numerical procedure for modeling sliding and nonsliding joint constraints for the B-spline thin plate element is developed for the large deformation analysis of multibody systems. A concept of intermediate reference coordinates proposed for the absolute nodal coordinate formulation is generalized for B-spline elements such that a wide variety of joint constraints can be modeled using existing joint constraint libraries already implemented in multibody dynamics codes. This procedure allows for modeling sliding joints for B-spline elements that requires a solution to moving boundary problems by introducing time-variant surface parameters in the B-spline parametric domain. Since surface parameters treated as knot variables in the basis function are defined in the entire parametric domain rather than the element domain, the location of the constraint definition point can be determined without knowing in which elements the sliding point is located. Furthermore, using the B-spline recurrence formula, control points used for describing the constraint equations can be systematically extracted. It is shown that many types of nonsliding joints fixed on the flexible body can also be modeled as a special case of the sliding joint formulation developed in this investigation, leading to a unified joint constraint formulation for B-spline elements. Several numerical examples are presented in order to demonstrate the use of the numerical procedure developed in this investigation.
Boundary Conditions That Govern the Lateral Behavior of Flexible Webs in Roll to Roll Process Machines
Authors: Fu B. , Reddy A. , Vaijapurkar S. , Markum R. , Good J. K.
Published: August 2013

Thin web materials are commonly transported through machinery where a process adds value to the web. The flexible web is supported intermittently by contact with rollers. The friction forces associated with this contact are largely responsible for determining the lateral mechanics and dynamics of the thin web transiting rollers in roll-to-roll process machinery. The investigation focuses on cases where slippage between the rollers and web has become substantial and has resulted in a complex lateral behavior of the web. Two methods are presented for investigating the frictional forces and the resulting lateral behavior. The first method employs explicit finite element (FE) dynamic analysis to study the lateral mechanics of the web after steady state behavior has been achieved. This method allows the direct study of the frictional forces. The second method employs Laser Doppler Velocimetry in a novel experimental noncontact technique to examine internal loads within the web, which were influenced by the frictional forces. Both methods are shown to provide results, which agree with one another and with previous analysis. The analyses are used to form a new friction boundary condition between a web and roller that will benefit other analysis methods.
Stability Analysis of Multibody Systems With Long Flexible Bodies Using the Moving Modes Method and Its Application to Railroad Dynamics
Authors: Chamorro Rosario , Escalona José L. , Recuero Antonio M.
Published: August 2013

In order to model a long flexible body subjected to a moving load within multibody systems, the flexibility can be considered by using a special floating frame of reference approach. In this approach the body deformations are described using shape functions defined in a frame of reference that follows the load. The definition of the deformation shape functions in the load-following frame of reference leads to additional terms of the inertia forces of the flexible body. This method was recently presented by the authors and named the moving modes method. The selected shape functions used in this work are the steady deformation shown by a flexible straight body subjected to a moving load. In this investigation the new formulation is applied to the steady motion and stability analysis of railroad vehicles moving on curved tracks.
An Analytical Approach for Synthesizing Line Actuation Spaces of Parallel Flexure Mechanisms
Authors: Yu Jingjun , Li Shouzhong , Qiu Chen
Published: August 2013

In this study, we present an analytical approach for synthesizing line actuation spaces of a parallel flexure mechanism (PFM) that can help designers to arrange linear actuators within the PFM in a correct and optimal way. On the basis of screw theory and upon an assumption of small deformations, an important synthesis criterion stated as “any actuation space of a flexure mechanism is always linearly independent of its constraint space” has been derived and disclosed for the first time. Guided by this criterion, a general synthesis process for the line actuation spaces of PFMs is introduced and demonstrated with several selective examples. The proposed synthesis criterion and process will enable designers to (i) systematically formulate line actuation spaces in the format of screw systems; (ii) likely yield a multiple solution to actuation spaces; and (iii) potentially determine an optimal result from those alternatives for actuator placement.
A Stochastic Model for Long-Term Trends in Significant Wave Height With a CO2 Regression Component
Authors: Vanem Erik
Published: August 2013

Bad weather and rough seas continue to be a major cause for ship losses and is thus a significant contributor to the risk to maritime transportation. This stresses the importance of taking severe sea state conditions adequately into account, with due treatment of the uncertainties involved, in ship design and operation. Hence, there is a need for appropriate stochastic models describing the variability of sea states. These should also incorporate realistic projections of future return levels of extreme sea states, taking into account long-term trends related to climate change and inherent uncertainties.

The stochastic model presented in this paper allows for modelling of complex dependence structures in space and time and incorporation of physical features and prior knowledge, yet at the same time remains intuitive and easily interpreted. A regression component with CO2 as an explanatory variable has been introduced in order to extract and project long-term trends in the data. The model has been fitted by significant wave height data for an area in the North Atlantic ocean. The different components of the model will be outlined in the paper, and the results will be discussed.
Explosion Safety Drivers for Arctic Platform Designs
Authors: Dalheim Joar , Nodland Sverre , Pappas Jan
Published: August 2013

The unique and harsh environment of the arctic region requires specialized process area designs and safety solutions. One main process safety issue in the arctic is the need for more enclosed modules. Enclosed modules are used for two reasons; to prevent ice and snow to expose the process equipment; and to prevent the cold climate to impose an unduly harsh working environment for operators. The enclosed mechanically ventilated process modules are different from the open naturally ventilated process modules that are normally used in offshore facilities. The explosion safety performance of the non-standard mechanically ventilated process modules has therefore been studied in detail through several extensive programs of CFD simulations; see [1], [2] and [3]. It is seen that confined and mechanically ventilated modules has explosion risk drivers that are distinctly different from open and naturally ventilated modules. The following is seen to have significant impact on the explosion risk levels on confined process modules; the module size; the HVAC philosophy; the ignition source isolation efficiency; and the use of pressure release panels. These factors, and their impact on the explosion risk, are discussed in this paper. The presented conclusions are of high importance in future developments in arctic climate.
Arctic FPSO: Technical Feasibilities and Challenges
Authors: Li Guang (George)
Published: August 2013

FPSO (Floating Production Storage Offloading) vessels are ideally suited for development of remote-region projects because tankers and onsite storage are needed to transport crude oil to markets. Even for the basins where pipelines are eventually built, an FPSO can still serve as an early production system to reduce project risk and improve project cash flow. Therefore, an FPSO offers an attractive solution to deepwater fields in the Arctic where fixed platforms are not feasible from either technical or commercial perspectives.

The technical feasibility of an arctic FPSO depends on ice and iceberg conditions. In iceberg infested water, the arctic FPSO needs to be disconnectable to avoid collisions with incoming icebergs. Even without the presence of icebergs, an Arctic FPSO may need to be disconnectable due to the limits of stationkeeping capacity of its mooring system. Design of a disconnectable mooring system becomes significantly more challenging than a permanent one because of the additional requirement of load transfer, disconnected subsea system, disconnections and reconnections. These requirements often conflict with the ones of flow assurance, topside layout, ventilation and fire protection. These conflicting requirements are discussed and technology gaps are identified in this paper.
Comparison and Assessment of the Crashworthiness of Three Innovative Side-Shell Structures: The X-Core, Y-Core and Corrugation Panel Structures
Authors: Ringsberg Jonas W. , Hogström Per
Published: August 2013

Collisions between ships contribute to ship losses even in modern time. In numerous research projects, new innovative side-shell structures have been proposed and assessed in contrast to conventional side-shell structure designs with respect to their crashworthiness properties. The current paper presents an in-depth comparison and assessment (by means of experiments and nonlinear finite element simulations) of three innovative side-shell structures referred to as the X-core, the Y-core and the intrusion-tolerant corrugated panel structures; all of them have been presented separately in the literature before. The objective is to compare the three concepts against a typical reference double-hull side-shell structure and challenge their structural designs with respect to energy absorption, penetration depth at fracture of the inner barrier during a bulb-impact loading condition, weight and manufacturing cost. It is concluded from the investigation that there is not one candidate who is superior to the others. Hence, the structures have to be further developed or trade-offs have to be made depending on the indented functionality of the structure and risk for collision related to e.g. distribution of likely collision angels.
Full-Scale Site Investigations on Soil-Plugging Inside Tubular Piles
Authors: Henke Sascha
Published: August 2013

Soil-plugging inside open-ended piles is a well-known phenomenon which increases vertical bearing capacity on the one hand but also leads to increasing driving resistance. There are many different factors affecting the tendency of soil-plug formation like pile diameter, geometry of the pile, installation method, soil density and so on. In the present contribution, in-situ measurements regarding two tubular piles with a diameter of 71 cm are presented. The piles are first vibratory driven up to 6.5 m penetration and afterwards they are impact driven to their final penetration depth. During the installation internal and external stresses at the pile toe and accelerations and strains at the pile head are measured on both piles. Furthermore, one pile is equipped with a cone penetrometer inside the pile to monitor cone and shaft resistance during the installation. At the end of the installation the height of the internal soil column is measured. The results are discussed with focus on the installation method on soil plugging tendency. Concluding they are compared to classical analytical approaches.
Wellhead Fatigue Analysis Method: A New Boundary Condition Modelling of Lateral Cement Support in Local Wellhead Models
Authors: Reinås Lorents , Sæther Morten , Svensson Johan
Published: August 2013

Subsea wells are dynamically loaded during all drilling operations involving a drilling riser system which will cause fatigue loading of the subsea wellhead system and the upper structural components of a well. Estimation of loads and load resistance enables analysts to predict expected service life based on analytical models of well and riser systems. Analytical wellhead models may be a simplified representation of the reality but should still capture the essential physical behavior of the well. Ensuring sound boundary conditions for the analytical model is important and subject to debate amongst analysts. This paper addresses the importance of the well cement as a lateral supporting boundary condition of the wellhead and surface casing in local modelling of a subsea wellhead system. A modified boundary condition approach is suggested that differs from the previously published way of modelling cement in a wellhead fatigue context. This modified boundary condition is applied both to a 2D FEM wellhead model and to a more complex 3D FEM wellhead model. Analysis results with the new boundary condition and the previously suggested boundary condition are compared to understand the effect this modified cement boundary condition has on the analytical results. The effective level of cement is varied to investigate the sensitivity of cement boundary condition modelling. Results indicate less conservative analytical results for the modified boundary condition both for 2D and 3D modelling. The modified cement boundary condition suggested herein is believed to be relevant for deepwater and high latitude subsea basins as it takes into account the hindered strength development of oil well cement cured close to seabed under the influence of low seawater temperatures. We advocate that installation of BOP before cement has properly cured will improve fatigue life of surface casing weld.
Fatigue and Fracture of Mechanically Lined Pipes Installed by Reeling
Authors: Tkaczyk Tomasz , Pépin Aurélien , Denniel Sylvain
Published: August 2013

There is an increasing need for transport of corrosive constituents in the subsea oil and gas sector, which generates a high demand for corrosion resistant alloys. Stainless steel, such as duplex, is routinely used for subsea pipelines. Clad pipe with a thin CRA layer metallurgically bonded to a carbon steel pipe is also widely applied, especially for high temperature pipelines and SCRs as it does not suffer from significant strength reduction at high temperature and has an excellent fatigue performance in sour environment.

The interest has grown in lined pipe, which combines the benefits of clad pipe with more attractive procurement costs and shorter lead times. Here, CRA and carbon steel are adhered by means of an interference fit. The authors have patented and qualified a lined pipe design, which enables safe reeled installation without internal overpressure. To extend the field of applications of lined pipe, large scale bending and fatigue tests have been carried out in this work. It has been confirmed that the novel reeled lined pipe is suitable for SCR service.
The Use of Empirical Orthogonal Functions for Deriving Response Based Extreme Current Profiles
Authors: Jeans Gus , Harrington-Missin Liam , Watson Andrew , Upton Jon
Published: August 2013

Coherent extreme current profiles are derived to reduce the over-conservatism associated with the traditional assumption that extreme currents occur at all depths through the water column simultaneously. Empirical Orthogonal Function (EOF) analysis has proven effective for derivation of coherent extreme current profiles in regions where it effectively captures the dominant characteristics of the flow regime. This is despite the questionable suitability of EOF for Current Profile Characterisation, which reduces a large current profile data set into a much smaller set of profiles for riser fatigue studies.

EOF Mode 1 and 2 are used to represent six years of in-situ current profiles accounting for 97.75% of the original variance. With the assumption that depth integrated speed squared is proportional to drag on a simple riser, three sets of extreme current profiles were derived. A) Profiles associated with extreme near surface current speeds, B) Profiles associated with extreme mid-depth current speeds and C) Profiles associated with extreme drag on a riser.
The Effects on Facilities and Crew Members of the Ice-Resistant Platforms Induced by Ice Vibrations in Bohai Sea
Authors: Zhang Dayong , Yue Qianjin , Li Huihui , Huang Yanan
Published: August 2013

The current design and safety assessment of ice-resistance platforms have usually been considered the maximum bearing capacity under the extreme static ice loads. However, the effects on the facilities and crew members induced by the dynamic ice loads are not been considered, and the risks are greater than the structure security. So it is necessary to analyze the effect on the facilities and crew members by ice-induced vibrations. Based on the data monitored on the platforms in the Bohai Sea and the ISO standard about human body in vibration environment, human fatigue on the platforms is evaluated. The typical history curve of the deck acceleration is obtained and used to analyze the excitation of pipelines. A mechanical model of structural vibration of pipeline system is developed. With finite element modeling, the dynamic responses of the pipeline systems induced by deck vibration are calculated. The results show ice-induced vibration may have major effect on the crew members and the facilities, and this failure mode by strongly ice-induced accelerations should be considered in safety producing of the existing platforms and optimization design of the new platforms.
Effect of Environmental Factors on Corrosion Fatigue Performance of Duplex 2507
Authors: Thodla Ramgopal , Joia Carlos , Baptista Palmieri
Published: August 2013

Corrosion fatigue performance of welded duplex 2507 riser material environments containing high partial pressures of carbon dioxide (100–200 bar) and limited quantity of hydrogen sulfide (0–0.12 bar) is presented in this paper. da/dN vs ΔK at different frequencies as a function of various environmental were studied. In the range of environments studies there was no significant environmental effect on the FCGR. da/dN measurements were performed starting at an initial ΔK of 150Nmm-3/2 and crack growth was readily established suggesting that ΔKth were lower than this value. Frequency scan tests were performed in various environments and the FCGR was found to be weakly dependent on frequency. The highest increase in FCGR was about 3–4x over the air values. The effect of duplex microstructure will also be discussed by comparing results from plate samples of 2507 with differing microstructure. The FCGR was higher with the plate samples which had precipitation of ferrite within the austenite grains which may have led to the higher FCGR. Frequency scan results for the plate samples will be compared with the results from the riser material.
Experimental Investigation of the Effects of a Pulsating Internal Flow on the Dynamics of a Submersed U-Shaped Flexible Pipe
Authors: Yamamoto Marcio , Uto Shotaro , Fujiwara Tomo , Murai Motohiko
Published: August 2013

In the past of the offshore petroleum production, each riser had conveyed the hydrocarbon production from a single vertical well; the riser’s internal flow rate was relatively low and only the internal fluid pressure was taking into account for the riser analysis. Other internal flow effects, such as internal fluid’s linear moment, and Coriollis effects, were neglected. However, the paradigm for petroleum production in ultra-deepwater is shifting nowadays. New technologies, such as horizontal wells, have increased the production rate from a single well. In addition, a subsea booster system can increase both pressure and flow rate of the riser’s conveyed fluid. Further, the Offshore Mining is rising as a new industry and will demand riser systems to convey, at high flow rates, the mineral ore’s slurry from the seafloor up to the production support vessel. In a previous experiment, the effects of the internal flow on a vertical riser were investigated. In the current experiment, the main objective is to investigate the effect of the internal flow on the dynamic response of a pipe in “jumper configuration”. The experiment was carried out at the Deep Sea Basin of the National Maritime Research Institute using a 10 m long flexible pipe. The actual “jumper” is a piece of flexible riser, in U-shaped configuration, that connects the main structure of “Self-Standing Hybrid Riser” to the production vessel. During the experiment, fresh water was pumped into the model by positive displacement pump; and an oscillator applies a harmonic vibration on one pipe’s end. Then the pipe’s dynamic response is measured by the Deep Sea Basin’s 3D Visual Measurement System. Results for different internal flows and oscillations are compared.
The Fatigue Crack Propagation of the Ship Structures in Random Sea States
Authors: Feng Guoqing , Cao Junwei , Ren Huilong , Li Hui
Published: August 2013

The traditional method for the fatigue strength assessment of ship structures is based on S-N curves and Miner linear cumulative damage rules. However, with the development of the ship mechanics, the fracture mechanics method has aroused people’s attention. Some researchers have begun to use the fracture mechanics method to perform the fatigue strength assessment of ship structures. A fracture mechanics based approach for the fatigue assessment of ship structures in random sea states is presented. First, the fatigue stress history of the ship structures in random sea states is simulated. Then, the stress intensity factor in random sea states is calculated through the weight function and the fatigue stress of the ship structures in random sea states. Finally, the crack growth is calculated using Pairs equation for each stress cycle throughout the fatigue stress history of the ship structures in random sea states.
Development of a Relationship Between Residual Ultimate Longitudinal Strength Versus Grounding Damage Index Diagram for Container Ships
Authors: Kim Do Kyun , Kim Han Byul , Zhang Xiaoming , Pedersen Preben Terndrup , Kim Min Soo , Paik Jeom Kee
Published: August 2013

Various accidents such as grounding, collision, fire, and explosion commonly occur on operating ships. The structural damage caused by such accidents is often accompanied by casualties and serious pollution. Therefore, an accidental risk-based approach that is in line with the goal-based standard of the International Maritime Organization is being developed in the literature. In the present paper, the residual ultimate longitudinal strength versus grounding damage diagram (R-D diagram) for container ships is established as per the method of Paik et al. [1]. The proposed R-D diagram should be useful for defining acceptance damage criteria and making rapid salvage plans or rescue schemes for container ships that have sustained a grounding accident.
Dynamic and Fatigue Analyses of Stress Joint for Deepwater Steel Catenary Riser
Authors: Yang Hezhen , Zheng Wenqing
Published: August 2013

As the offshore industry continues to progress developments in deepwater, Steel Catenary Riser (SCR) offers great advantages over other risers. In order to provide the hang-off with sufficient stiffness, stress joint is used to connect the riser with platform. When stress joints are located at the top of a deep marine riser, it is greatly affected by both axial and bending stress due to great cyclic loading. So it is necessary to do some research on dynamic and local fatigue analyses for stress joint.

In this work, global dynamic analysis for a SCR is performed firstly, then local boundary condition obtained from the previous analysis are applied to the stress joint FE model for time domain dynamic and multiaxial fatigue analysis. Results indicate that the stress level is far lower than yield limit of material and damage induced by fatigue needs more attention. Besides, the damage character of the two types of stress joints differs: for TSJ, the place where stress joint connects with riser is easy to occur fatigue damage; for SSJ, the most probable position is at the place where the end of inner sleeve pipe contacts with the riser body. Compared with SSJ, TSJ shows a higher stress level but better fatigue performance, and it will have a higher material cost. Considering various factors, designers should choose the most suitable type and also geometric parameters.
Simplified Approaches to Modeling of Lateral Wire Buckling in the Tensile Armour of Flexible Pipes
Authors: Østergaard Niels H. , Lyckegaard Anders , Andreasen Jens H.
Published: August 2013

In the present paper, simplifications of methods developed for modeling of lateral wire buckling in the tensile armour layers of flexible pipes are proposed. Lateral wire buckling may occur during pipe laying in ultra-deep waters. In this scenario a flexible pipe is subjected to repeated bending and axial compression due to hydrostatic pressure on the end cap of an empty pipe. If the outer sheath is breached, these loads may cause wire slippage towards states in which the load carrying ability is reduced and wire buckling in the circumferential pipe direction occurs. This leads to characteristic deformation patterns, which may compromise the structural integrity of the entire pipe structure. On the other hand, these loads may cause overstressing of the wires, if the outer sheath is intact.

Simplifications of established models for calculation of the load carrying ability are in the present context proposed in a manner, by which the effect of adjacent pipe layers on the postbuckled response can be estimated. The simplifications enables significant reduction of the computational time, which is necessary to calculate the load carrying ability of a given pipe structure.
Experimental Study on the Impact Loads Acting on a Horizontal Rigid Cylinder During Vertical Water Entry
Authors: Van Nuffel Diederik , Vepa Sridhar , De Baere Ives , Degrieck Joris , De Rouck Julien , Van Paepegem Wim
Published: August 2013

This paper experimentally studies the local and global loads acting on a rigid cylinder subjected to water wave slamming. Local loads are hereby expressed in terms of pressure on the cylindrical surface while global loads are investigated in terms of force acting on the complete cylinder. Global impact loads may be better suited for use in design processes. An experimental setup to perform vertical drop experiments to approximate wave slamming is presented and the necessary measuring equipment is described. The experimental results are firstly discussed in the time domain to understand what exactly is happening during the water entry and in what stage the maximum loads occur. The measurements learn that the time scale of the pressure and the force histories is considerably different. Secondly, the attention is focused on the peak values of the time plots. These impact pressures and impact forces are represented as function of the impact velocity. The pressure is hereby given for different positions along the circumference of the cylindrical surface. The experiments show that the impact pressure and force increase very fast with growing impact velocity, indicating that large loads accompany waves with large velocities. Wave slamming is thus an important design criterion for all kind of cylindrical structures when exposed to harsh sea conditions.
Motion Analysis of Floating Type Current Turbines
Authors: Takagi Ken
Published: August 2013

Ocean current energy is one of promising power resource for Japan, since “Kurosio”, which pass through near the Japanese coast, is one of strongest ocean current in the world. In order to catch this energy, floating type marine current turbines i.e. the contra-rotating system and the twin turbine system, are proposed which are designed so that the rated current velocity is 1.5m/s. Three dimensional motions of these systems with effects of turbines are formulated. Basing on this formulation, a computer code to simulate the device motion and the blade forces is developed in which the linearized mooring forces are used. Some numerical results are shown, and the difference between the dynamic motion of the contra-rotating turbine system and that of the twin turbine system in waves is discussed.
Consequences of Failure Estimation for Oil and Gas Spills
Authors: Bai Yong , Bakar Shahirah Abu , He ShiLiang , Mohd Arif Abu Bakar
Published: August 2013

This paper reviews the consequence of failure (CoF) estimation for oil and gas spills based from Quantitative Risk Assessment (QRA) study. The main purpose of QRA is to determine the target reliabilities for each different pipeline system segments; and the purpose of CoF is to determine the failure consequences including amount and rate of oil spill and gas spill, affected area, delaying mission or any other measurement of negative impact. However, this paper will focused on determination of oil spill slicked and gas spill leakage within a leakage in a pipeline system. Then, a suitable action can be performed based on these calculations and data to avoid the consequences of failure such as number of people effected, production cost affected, environment area affected, etc. In some cases, event tree analysis will be performed especially for consequences of gas spill. Oil spill modeling is performed by using ADIOS software to stimulate the oil spilled evaporation, while oil slick calculation and gas spill leakage modeling is from common mathematical software to calculate the failure consequences. The purpose of both modeling is to simulate the potential spills with varying leakage sizes at different sections of the pipeline systems.
Mating Analysis and a Typical Floatover Design
Authors: Wang Alan M. , Yuan Ruhua , Zhu Shaohua , He Min , Fan Ju , Miao Guoping
Published: August 2013

This paper presents a typical floatover design in the shallow water and benign environment of Bohai Bay, China and the major floatover installation devices, as well as the nonlinear time-domain mating analysis. The nonlinear mating simulations are performed using SIMO based on the hydrodynamic properties of the floatover barge, obtained by WADAM, from the linear diffraction analysis in frequency domain. The mating analysis yields numerical findings in selecting and designing floatover devices critical to the success of the floatover operations, thus minimizing any potential operation risks and enabling the offshore operations as smoothly and efficiently as possible.
CFD Virtual Testing for Resistance, Wind and Current Loads on a Supply Boat
Authors: Silva Daniel Fonseca de Carvalho e
Published: August 2013

Ship and platforms environmental loads are often predicted by model scale experiments or empirical calculations only. This paper presents the application of a commercial CFD (Computational Fluid Dynamics) software as a numerical approach to calculate the flow around a supply boat considering current, wind loads and fluid resistance determination. Since, owing to many practical situations, free surface effects can be neglected, the above and underwater problems can be uncoupled and independently evaluated, although for higher Froude number cases in the resistance determination the interfacial effects have to be considered. Throughout this paper, the assumptions adopted and the boundary conditions applied are discussed. All meshes were developed on ICEM CFD® and appropriate mesh density studies indicate that meshes with approximately 2 million nodes can represent the experiments accurately. The simulations were conducted using the ANSYS CFX® solver, using Perl scripting for automatic evaluation of multiple run settings and simulation execution at Petrobras Research Center Clusters. The results for each case are compared with either towing tank or wind tunnel experimental data, both harvested at IPT (Instituto de Pesquisas Tecnológicas). The comparison between simulation results and experiments allows the analysis of the present CFD models benefits and limitations, providing guidelines for future similar studies. The overall match between laboratory and virtual tests results supports the expansion of this procedure to other vessels and offshore floating units.
Extreme Wave Analysis in Campos Basin (Rio de Janeiro - Brazil) Associated With Extra-Tropical Cyclones and Anticyclones
Authors: Campos Ricardo M. , Parente Carlos Eduardo , de Camargo Ricardo
Published: August 2013

Campos Basin is a petroleum rich area located offshore of Rio de Janeiro, Brazil. The most energetic ocean waves that reach location are generated by extra-tropical weather systems. This article studies extreme waves generated by cyclones and anticyclones, using two approaches. The first is the statistical extreme analysis applying the Peaks Over Threshold technique. The second is an evaluation of metocean features of events selected by POT as the tail of distribution. The research used 42 months of directional wave buoy measurements from 1991 to 1995 and 20 years of WAVEWATCH III simulation from 1986 to 2005, forced by NCEP/NCAR reanalysis2 surface winds. From metocean evaluation, the authors conclude that the greatest swells hitting Campos Basin come from southwest direction, peak periods over 11 seconds, generated by cyclones, occurring mainly in winter and autumn. The extreme buoy data analysis of significant wave height resulted in return values for 50 and 100 year respectively 8.77 and 9.54 meters, but with considerable uncertainty due to the short duration of data collection. Despite the limitations of Wavewatch hindcast, the methodology was able to capture the characteristics of extreme events in terms of shape of the distribution tail.
Assessment of Different Technologies for Vertical Hydraulic Transport in Deep Sea Mining Applications
Authors: Verichev Stanislav , Drobadenko Valery , Malukhin Nikolay , Vilmis Alexandr , Lucieer Pieter , Heeren John , van Doesburg Bob
Published: August 2013

Successful mining of deep sea deposits strongly depends on the proper choice of the right equipment. The most probable concept for a deep sea mining system would consist of the three major sub-components: Seafloor Mining Tool, Vertical Transport System and Mining Support Vessel. In this paper, emphasis is placed on the Vertical Transport System. We analyse the pros and cons of the different concepts such as hydraulic transport using centrifugal or positive-displacement slurry pumps, conventional and unconventional airlift systems, vertical offshore mining systems and vortex slurry transportation systems. All these systems are considered for their applicability at different water depths (from the relatively shallow to the relatively deep) for the different types of materials (from the relatively fine to the relatively coarse) and various production rates in terms of the efficiency, reliability and state of the art of technology.
Forced Motion Experiments With Measured Motions From Flexible Beam Tests Under Uniform and Sheared Flows
Authors: Yin Decao , Larsen Carl M.
Published: August 2013

Hydrodynamic forces on a cylinder under realistic combinations of in-line (IL) and cross-flow (CF) vortex induced vibrations (VIV) have been investigated.

Signals of strain gauges and accelerometers from the Norwegian Deepwater Programme (NDP) tests with a long, slender beam were used to identify cross section orbits. 19 cross sections almost evenly distributed along the pipe were selected, and their motions were applied in controlled motion experiments with a rigid cylinder. Dimensionless parameters like Reynolds number and non-dimensional frequency were identical for the two sets of experiments.

Comparison between hydrodynamic coefficients found from forced motion tests with observed motion time histories and periodic approximations are presented. Force histories are also investigated in detail.

Orbit types for combined IL and CF VIV are categorized based on relative amplitude and phase, and it is shown that IL motions exhibit chaotic character more easily than CF. Amplitude modulation is observed frequently.

Cases where cross section motions are close to periodic have similar hydrodynamic forces as for periodic motion, implying that periodic forced motion tests are relevant to get valid force information. Many cases have amplitude modulated IL motions, while CF motions are quasi-steady. In such cases, IL amplitude modulation can cause abrupt change of IL forces and also 3rd order CF forces, which can accumulate large fatigue damage. When both IL and CF motions are chaotic, the force-motion relationship is impossible to describe by constant coefficients.
Analysis of the Creep Behaviour of the Polymer Barrier Layer in Unbonded Flexible Pipes Under Different Fluid Temperatures
Authors: Shen Yijun , Zhao Jian , Tan Zhimin , Sheldrake Terry
Published: August 2013

This paper discusses the influence of different fluid temperatures on the creep behaviour of the polymer barrier inside unbonded flexible pipes. The creep behaviour of the polymer material is generally time-dependent and associated with larger, nonlinear deformation. Excessive creep deformation may lead to structural failure, due to the over-reduction of the barrier layer thickness, and is therefore an important design consideration in ensuring the structural integrity of this layer.

Creep behaviour in polymer material is complex, as it is governed by a number of variables, such as the stress/strain state, temperature, and pressure for example. This paper deals with the influence of different fluid temperatures on the creep behaviour of the polymer barrier layer under pipe design pressures, particularly in high temperature fluid transportation pipelines for deep or ultra-deep sea applications.

The analysis model was established using commercial finite element software ANSYS, where an implicit time hardening creep model, based on the Maxwell viscoelastic model, was selected to represent the creep behaviour of the polymer materials. The coefficients of the implemented polymer material gap span creep model are calibrated to represent the worst case of the small-scale sample gap span creep tests performed in-house.

A comparison is made between the simulation results of the calibrated gap span creep model and the corresponding small-scale creep test measurements. The experimental test results and the finite element modelling results show good correlation. This demonstrates that the creep model predictions are conservative for the polymer material of the barrier layer inside an unbonded flexible pipe.
Residual Stress Management in Welding: Residual Stress Measurement and Improvement Treatments
Authors: Kleiman Jacob , Kudryavtsev Yuri
Published: August 2013

Residual stress (RS) can significantly affect engineering properties of materials and structural components, notably fatigue life, distortion, dimensional stability, corrosion resistance etc. Residual stresses play an exceptionally significant role in fatigue of welded elements. The influence of residual stresses on the multi-cycle fatigue life of butt and fillet welds can be compared with the effects of stress concentration. Even more significant are the effects of residual stresses on the fatigue life of welded elements in the case of relieving harmful tensile residual stresses and introducing beneficial compressive residual stresses in the weld toe zones.

Residual stress management is a concept that addresses major aspects of residual stresses in welds and welded structures. According to the concept three major stages, i.e. RS determination, RS analysis and RS redistribution are considered and evaluated, either experimentally or theoretically to achieve the optimum performance of welded structures.

All three stages as well as a number of new engineering tools such as ultrasonic computerized complex for residual stress measurement, UltraMARS, software for analysis of the effect of residual stresses on the fatigue life of welded elements and new technology and, based on it, compact system for beneficial redistribution of residual stresses by ultrasonic peening, UltraPeen will be discussed. Examples of industrial applications of the developed engineering tools for residual stress analysis and fatigue life improvement of welded elements and structures will be given.
Development of the Inflow Boundary With a Free Surface to Apply the MPS Method to Tsunami Analysis on Coastal Areas
Authors: Masuda Koichi , Ikoma Tomoki , Aida Yasuhiro , Takayama Junpei
Published: August 2013

The wave maker of MPS method, a kind of particle method, with free surface is developed in this study. This wave maker has the function of the inflow and outflow of particles. Compared to piston-type wave maker, this is possible to reduce the particle for calculation keeping wave form. As a result, this way is faster computation than that. This way controlled by fluid velocity and wave elevation is able to input propagating tsunami of actual phenomenon and data generated by the other result of MPS method and able to continue simulation. This means that it is possible to simulate in detail with 3D-MPS method after 2D-MPS method that is less computationally expensive. This approach is applied to the analysis to tsunami in coastal area. In this study, fluid pressure of run-up-tsunami affecting a building with MPS method is compared and with experiment. And applying MPS method to analysis of run-up-tsunami is considered.
Effects of Plastic Deformation on Fatigue Life of Superduplex Steel Tube Umbilical
Authors: Burgos Diego F. S. , Parise Luís F. S. , Savioli Rafael G. , Donato Gustavo H. B. , Nascimento Filho Antonio P. , Lemos Carlos A. , Silva Neilon , Ruggieri Claudio
Published: August 2013

This work presents an experimental investigation of the effects of plastic strain on the fatigue behavior of superduplex steel tubes. Fatigue tests using conventional axial loading and a resonant bending setup conducted on 15mm OD tubes made of SAF2507 superduplex steel provides S × N data upon which effects of different levels of plastic strain can be assessed. Despite the inherent scatter in the measured fatigue data, the experiments reveal consistent trends and relatively small effects of plastic strain on fatigue behavior of superduplex steel tubes.