bluuebunny/crossref_metadata_2025 huggingface dataset:
Anthropogenically induced adaptation to invade (AIAI): contemporary adaptation to human‐altered habitats within the native range can promote invasions
Authors: Hufbauer Ruth A. , Facon Benoît , Ravigné Virginie , Turgeon Julie , Foucaud Julien , Lee Carol E. , Rey Olivier , Estoup Arnaud
Published: November 2011

Adaptive evolution is currently accepted as playing a significant role in biological invasions. Adaptations relevant to invasions are typically thought to occur either recently within the introduced range, as an evolutionary response to novel selection regimes, or within the native range, because of long‐term adaptation to the local environment. We propose that recent adaptation within the native range, in particular adaptations to human‐altered habitat, could also contribute to the evolution of invasive populations. Populations adapted to human‐altered habitats in the native range are likely to increase in abundance within areas frequented by humans and associated with human transport mechanisms, thus enhancing the likelihood of transport to a novel range. Given that habitats are altered by humans in similar ways worldwide, as evidenced by global environmental homogenization, propagules from populations adapted to human‐altered habitats in the native range should perform well within similarly human‐altered habitats in the novel range. We label this scenario ‘Anthropogenically Induced Adaptation to Invade’. We illustrate how it differs from other evolutionary processes that may occur during invasions, and how it can help explain accelerating rates of invasions.
Music: And So to the Movies
Authors: BURDEN MICHAEL
Published: November 2011

The study of music history has, in the last decades, seen a move away from the music of the canon, and of dead, white, male, ‘great’ composers, towards a closer engagement with performance and a clearer understanding of the contexts and institutions that produced music of all types. This article chooses five ways into the jungle of modern musical scholarship – monumental supporting projects; historical overviews; an independent voice for eighteenth‐century music research; performance practice; and music, celebrity and the cinema – and considers how they have shaped, and continue to shape, the subject as it is today.
South Asia: From Political Economy to Intellectual and Cultural Life
Authors: PARTHASARATHI PRASANNAN
Published: November 2011

From the 1970s the received wisdom of eighteenth‐century South Asian decline was replaced with a new vision of dynamism and change. Much of this work focused on issues of political economy, but more recently the study of the eighteenth century has broadened to include intellectual life, the arts and literature, in which there were lively indigenous traditions that were enriched from interaction with Europeans. Although political economy is less prominent in recent writings on eighteenth‐century South Asia, it cannot be omitted from the picture altogether, given that states and rulers were important patrons of many intellectual and artistic pursuits.
China: Pax Manjurica
Authors: NEWBY L. J.
Published: November 2011

This article looks at developments in Western historiography of eighteenth‐century China since the millennium. The opening of archives in the PRC and the development of online resources have facilitated new areas of study and continued the trend away from institutional and intellectual history and towards social and cultural history. Among the significant developments is the emergence of the ‘new Qing history’. The main debates and themes all have resonance in Western historical studies, but Eurocentric paradigms have invariably been rejected or significantly revised in order to construct culturally specific modes of analysis. These new interpretations are gradually filtering into mainstream writings and comparative studies.
Comparing three different surgical techniques used in adult bilateral varicocele
Authors: Sun HB , Liu Y , Yan MB , Li ZD , Gui XG
Published: November 2011

Introduction

Varicocele is a common disease in adult men that can be treated with one of several surgical methods. Each technique has advantages and disadvantages, and conflicting results have been obtained by different studies. To evaluate the most effective surgical techniques used in adult bilateral varicocele, including minimally invasive procedures, we compared the outcomes of three common surgical approaches in this prospective randomized study.

Methods

The study included 153 patients with bilateral varicoceles who underwent varicocelectomy. These patients were randomly divided into three equal groups according to surgical approach used – open inguinal, retroperitoneal or laparoscopic. The assessment included operative time, length of hospital stay, clinical outcome and, in cases of infertility, semen analysis. The mean follow‐up was 12 months (range, 8 to 15 months).

Results

The operative time and hospital stay in the laparoscopic group were significantly shorter than in the other groups (P < 0.01). Of the 51 cases in each group, there were seven cases (13.73%) of recurrence in the open inguinal group, six cases (11.76%) in the retroperitoneal group, and one case (1.96%) in the laparoscopic group. This lower rate of recurrence was statistically significant in the laparoscopic group (P < 0.05). Among the three groups, comparisons between preoperative and postoperative semen parameters showed visible improvements in sperm concentration and motility (P < 0.01), but there were no significant differences between the three groups for postoperative changes in semen parameters (P > 0.05).

Conclusions

Compared with open inguinal and retroperitoneal varicocelectomy, laparoscopic varicolerectomy offers the best outcome.
Fine‐grained precursors dominate the micrometeorite flux
Authors: TAYLOR Susan , MATRAJT Graciela , GUAN Yunbin
Published: November 2011

Abstract– We optically classified 5682 micrometeorites (MMs) from the 2000 South Pole collection into textural classes, imaged 2458 of these MMs with a scanning electron microscope, and made 200 elemental and eight isotopic measurements on those with unusual textures or relict phases. As textures provide information on both degree of heating and composition of MMs, we developed textural sequences that illustrate how fine‐grained, coarse‐grained, and single mineral MMs change with increased heating. We used this information to determine the percentage of matrix dominated to mineral dominated precursor materials (precursors) that produced the MMs. We find that at least 75% of the MMs in the collection derived from fine‐grained precursors with compositions similar to CI and CM meteorites and consistent with dynamical models that indicate 85% of the mass influx of small particles to Earth comes from Jupiter family comets. A lower limit for ordinary chondrites is estimated at 2–8% based on MMs that contain Na‐bearing plagioclase relicts. Less than 1% of the MMs have achondritic compositions, CAI components, or recognizable chondrules. Single mineral MMs often have magnetite zones around their peripheries. We measured their isotopic compositions to determine if the magnetite zones demarcate the volume affected by atmospheric exchange during entry heating. Because we see little gradient in isotopic composition in the olivines, we conclude that the magnetites are a visual marker that allows us to select and analyze areas not affected by atmospheric exchange. Similar magnetite zones are seen in some olivine and pyroxene relict grains contained within MMs.
Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near‐surface water on early Mars
Authors: FAIRÉN Alberto G. , DOHM James M. , BAKER Victor R. , THOMPSON Shane D. , MAHANEY William C. , HERKENHOFF Kenneth E. , RODRÍGUEZ J. Alexis P. , DAVILA Alfonso F. , SCHULZE‐MAKUCH Dirk , EL MAARRY M. Ramy , UCEDA Esther R. , AMILS Ricardo , MIYAMOTO Hirdy , KIM Kyeong J. , ANDERSON Robert C. , McKAY Christopher P.
Published: November 2011

Abstract– Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25 km‐long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10–80 m of deflation in the last 3–3.5 Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface.
Density, porosity, and magnetic susceptibility of carbonaceous chondrites
Authors: MACKE Robert J. , CONSOLMAGNO Guy J. , BRITT Daniel T.
Published: November 2011

Abstract– We report physical properties (bulk and grain density, magnetic susceptibility, and porosity) measured using nondestructive and noncontaminating methods for 195 stones from 63 carbonaceous chondrites. Grain densities over the whole population average 3.44 g cm−3, ranging from 2.42 g cm−3 (CI1 Orgueil) to 5.66 g cm−3 (CB Bencubbin). Magnetic susceptibilities (in log units of 10−9 m3 kg−1) averaged log χ = 4.22, ranging from 3.23 (CV3 Axtell) to 5.79 (CB Bencubbin). Porosities averaged 17%, ranging from 0 (for a number of meteorites) to 41% (for one stone of the CO Ornans). Notably, we found significant differences in porosity between the oxidized and reduced CV subgroups, with the porosities of CVo averaging approximately 20% and CVr porosities approximately 4%. Overall, porosities of carbonaceous chondrite falls trend with petrographic type, from type 1 (CI) near 35%, type 2 (CM, CR) averaging 23%, type 3 (CV, CO) 21%, to type 4 (CK and some CO) averaging 15%. There is also a significant decrease in porosity between meteorites of shock stage S1 and those of S2, indicative of shock compression.
The shared signal hypothesis: Effects of emotion‐gaze congruency in infant and adult visual preferences
Authors: Rigato Silvia , Menon Enrica , Farroni Teresa , Johnson Mark H.
Published: November 2011

In this study, 4‐month‐old infants’ and adults’ spontaneous preferences for emotional and neutral displays with direct and averted gaze are investigated using visual preference paradigms. Specifically, by presenting two approach‐oriented emotions (happiness and anger) and two avoidance‐oriented emotions (fear and sadness), we asked whether the pattern of emotion–gaze interaction suggested by the shared signal hypothesis (SSH) would also be found with this paradigm. Both age groups demonstrated an ability to discern the approach‐ and avoidance‐oriented emotions, matching them with direct and averted gaze, respectively. Nonetheless, infants showed a greater sensitivity for the congruent emotion‐gaze combination in the approach‐oriented emotions, while adults were equally sensitive to the gaze‐expression congruence for both the approach‐ and avoidance‐oriented emotions. In a follow‐up experiment, infants showed no preference for direct or averted gaze in the context of neutral faces. We conclude that the SSH may have validity from infancy, gradually extending from approach‐oriented emotions to avoidance‐oriented emotions over the course of development.
Mid Thickness Delayed Cracking of Z-Quality Offshore Steel
Authors: Gra˚berg Stig , Volden Lars , Paauw Anthonius Johannes
Published: November 2011

During fabrication of a steel structure for an offshore modification project, delayed cracking was experienced in the mid plane or centre line of a 30 mm thick plate. The plate was part of a restraint box frame where 25 mm plates were welded to this 30 mm plate on both plate-surfaces. The applied 30 mm plate was a higher strength offshore steel (EN10225-S420 G2+M), with special through thickness properties and enhanced chemical composition as defined in material data sheet MDS Y30 of NORSOK M-120. Fracture mechanical testing including KV and CTOD in the mid plane confirmed that a very low toughness was present here with a brittle fracture type (cleavage). The plate was manufactured by the continuous casting process which due to centre line segregation resulted in high levels of manganese sulfide inclusions but also niobium carbides/nitrides. The plate manufacturer considered the documented toughness level as expected. Similar testing was performed on a 30 mm plate also delivered to the same material specification but of which the material certificate revealed a 10 times lower sulfur and phosphorus content indicating a much higher steel refinement. A significant higher toughness was obtained for this steel with high ductile behavior. Both steels showed a similar through thickness ductility, measured elongation for the through thickness tensile specimen, which implies that this property does not guaranty for the observed material behavior.
Experimental Comparisons to Assure the Similarity Between VIM (Vortex-Induced Motion) and VIV (Vortex-Induced Vibration) Phenomena
Authors: Gonc¸alves Rodolfo T. , Freire Ce´sar M. , Rosetti Guilherme F. , Franzini Guilherme R. , Fujarra Andre´ L. C. , Meneghini Julio R.
Published: November 2011

Vortex-Induced Motion (VIM) is another way to denominate the Vortex-Induced Vibration (VIV) in floating units. The main characteristics of VIM in such structures are the low aspect ratio (L/D < 4.0) and the unity mass ratio (m* = 1.0, i.e. structural mass equal water displacement). The VIM can occur in MPSO (Monocolumn Production, Storage and Offloading System) and spar platforms. These platforms can experience motion amplitudes of around their characteristic diameters. In such cases, the fatigue life of mooring and riser systems can be greatly reduced. Typically, the VIM model testing campaigns are carried out in the Reynolds range between 200,000 and 400,000. VIV model tests with low aspect ratio cylinders (L/D = 1.0, 1.7 and 2.0) and unity mass ratio (m* = 1.0) have been carried out at the Circulating Water Channel facility available at NDF/EPUSP. The Reynolds number range covered in the experiments was between 10,000 and 50,000. The characteristic motions (in the transverse and in-line direction) were obtained using the Hilbert-Huang Transform method (HHT) and then compared with results obtained in experiments found in the literature. The aim of this investigation is to definitely establish the similarity between the VIM and VIV phenomena, making possible to increase the understanding of both and, at same time, allowing some analytical models developed for VIV to be applied to the VIM scenario on spar and monocolumn platforms, logically under some adaption.
Wave Effect on Slotted Breakwaters Considering Evanescent Modes
Authors: Nejadkazem Omid , Gharabaghi Ahmad R. M.
Published: November 2011

The present paper outlines the numerical calculation of wave runup, maximum horizontal wave force on the breakwater and maximum overturning moment on the slotted breakwater. For regular waves, using eigenfunction expansion method, a numerical model is developed that can compute wave transmission coefficient, wave reflection coefficient, and runup and wave force and its related momentum acting on the breakwater. To examine validity of the developed models, experimental measurements of Isaacson (1998) are compared with numerical results. Comparisons between measured and predicted values show that the mathematical model is able to adequately reproduce most of the important features of the experimental results. Wave runup and maximum horizontal wave force decreases by increasing porosity. As the relative water depth increases, wave runup and wave force decreases with respect to an impermeable breakwater. On the other hand, decreasing of relative draft, leads to much more reduction of relative wave force and runup with respect to impermeable one.
Natural Convection - Subsea Cooling: Theory, Simulations, Experiments and Design
Authors: Gyles Brian R. , Hægland Bjarte , Dahl Tine Bauck , Sanchis Arnaud , Grafsro̸nningen Stig , Schu¨ller Reidar Barfod , Jensen Atle
Published: November 2011

In many future subsea projects, there will be a requirement to cool various fluid streams, either multi-phase or single phase. To meet this need, FMC Kongsberg Subsea AS (FMC) has undertaken a project to develop a practical and robust subsea cooler. The cooler is passive in that heat is transferred to the surrounding sea water by natural convection only. Because of the subsea application, the cooler must have a special geometry to meet requirements for modularization and easy installation/removal. The passive nature of the cooler means that the flow rate of the seawater coolant is not an independent variable, but is directly linked to the cooler geometry. Developing a design method for such coolers requires detailed knowledge of the important heat transfer parameters, to an accuracy far in excess of that normally required for industrial cooler design. This problem has been approached on several levels, including an extensive literature search, theoretical studies, and model testing. One of the first observations was that little research had been done previously on this type of cooler. Much information is available for various pieces of the problem, but it became clear that designing the cooler would require significant development work. Based on the knowledge gained during the initial theoretical studies, a theory for calculating cooler performance presuming one dimensional external coolant flow has been developed. While it is clear that the actual external flow is three-dimensional, the simplified theory gives important insights into how the various design parameters affect cooler performance. To fill in the gaps in theoretical knowledge, a series of model tests designed to quantify internal and external heat transfer coefficients for the special geometry is being proposed. The testing program covers several technical areas and has required the utilization of a number of advanced measurement techniques. For the next phase of the testing program, a complete new test facility has been constructed capable of testing coolers with cross-flows typical of ocean bottom currents. The cooler development program has provided new technology which will be used to construct robust and compact subsea coolers. Because of the emphasis on basic research, fundamental knowledge and insight of the heat transfer mechanisms governing the performance of this type of cooler are acquired. This knowledge gives FMC the capability to design and manufacture subsea coolers which are custom-made to match the exact requirements of a given application.
CFD Modeling of a Submersible in a Realistic Surfaced Sea State Condition for Predictions of Hydrodynamic Wave Impact Loading
Authors: Jiang Minyee , Drazen David , Lee Jack R.
Published: November 2011

Topside features on submersibles are subject to wave impact loading while surfaced. At the surface, operations are typically conducted at low to zero ship speeds so hydrodynamic loading is dominated by wave loading as opposed to bow/wave slamming which is typically evaluated for surface ships. The typical circular or cylindrical hull situated mainly below the water line places topside features right around the mean water line, where the largest wave impact loading is expected. The roll, heave, and pitching motion of such a hull shape and the curvature of the hull at the water surface may result in a different distribution of wave impact loading when compared to the expected loading on typical surface ship hull. Current studies have been conducted using traditional scale-model experiments complimented with computational fluid dynamic (CFD) methods to improve the predictions and the understanding of the contributing factors to the wave impact loading. The end goal is to try to validate CFD modeling methods for these submersible design cases to support the design process. The end products are design wave impact load requirements and ship operating guidance to help avoid damage due to wave impact load conditions.
Velocity, Pressure, and Dam-Break Similarity of Green Water Flow on a 3D Structure
Authors: Chang Kuang-An , Ariyarathne Kusalika , Mercier Richard
Published: November 2011

Flow dynamics of green water due to plunging breaking waves interacting with a simplified, three-dimensional model structure was investigated in laboratory. Two breaking wave conditions were tested: one with waves impinging and breaking on the vertical wall of the model at the still water level (referred as wall impingement) and the other with waves impinging and breaking on the horizontal deck surface (referred as deck impingement). The bubble image velocimetry (BIV) technique was used to measure the flow velocity. Measurements were taken on a vertical plane located at the center of the deck surface and a horizontal plane located slightly above the deck surface. The applicability of dam-break theory on green water velocity prediction for the three-dimensional model was also investigated. Furthermore, pressure measurements were performed at several locations above the horizontal deck surface for the wall impingement wave condition. Predictions of maximum impact pressure based on the measured pressure and flow velocities were investigated using the impact coefficient approach that links pressure with kinetic energy.
The Effect of Shape, Thickness and Boundary Imperfections on Plastic Buckling of Cones
Authors: Ifayefunmi O. , Błachut J.
Published: November 2011

Three types of imperfections are analysed in the current paper, and they are: (i) Initial geometric imperfections, i.e., deviations from perfect geometry, (ii) Variations in the wall thickness distribution, and (iii) Imperfect boundary conditions. It is assumed that cones are subject to: (a) axial compression only, (b) radial pressure only, and (c) combined loading, i.e., axial compression and external pressure acting simultaneously. Buckling strength of imperfect cones is obtained for all of the cases above. It is shown that the buckling strength is differently affected by imperfections, when cones are subjected to axial compression or to radial external pressure. The response to imperfections along the combined stability envelope is also provided, and these results are first of this type. The finite element analysis, using the proprietary code is used as the numerical tool. Cones are assumed to be from mild steel and the material is modelled as elastic perfectly plastic. Geometrical imperfection profiles are affine to eigenshapes. A number of them are tried in calculations, as well as the effect of them being superimposed. The results indicate that imperfection amplitude and its shape strongly affect the load carrying capacity of conical shells. Also, it is shown that the buckling loads of analyzed cones are more sensitive when subjected to combined loading as compared to their sensitivity under single load conditions. At the next stage, uneven thickness distribution along the cone slant was considered. Variation of wall thickness was assumed to vary in a piece-wise constant fashion. This appears to have a large effect on the buckling strength of cones under axial compression only as compared with that of cones subjected to radial external pressure only. Finally, the effect of variability of boundary conditions on failure load of cones was investigated for two loading conditions, i.e., for axial compression and for radial pressure, only. Results indicate that change of boundary conditions influences the magnitude of buckling load. For axially compressed cones the loss of buckling strength can be large (about 64% for the worst case (beta = 30 deg, the cone not restrained at small radius end). Calculations for radial pressure indicate that the loss of buckling strength is not as acute — with 34% for the worst case (beta = 40 deg, relaxed boundary conditions at the larger radius end). This is an entirely numerical study but references to accompanying experimental programme are provided.
Study on Wave Power Generator Using Flexible Piezoelectric Device
Authors: Mutsuda Hidemi , Kawakami Kenta , Hirata Masato , Doi Yasuaki , Tanaka Yoshikazu
Published: November 2011

We have developed a new wave power generator using flexible piezoelectric device (FPED) which is a hydro-electric ocean energy unit designed to convert renewable energy harnessed from ocean energy into usable electricity. In our previous works, the FPED consisting of piezo-electric polymer film (PVDF) is a way of harvesting electrical energy from the ocean power, e.g. tide, current, wave, breaking wave and vortex. The concept of this study is that the existing coastal and ocean structures (i.e. breakwater, submerged obstacle, reef in shallow water and submerged plate in deep water) are utilized as a wave power generator attached with the FPED to make a safety and disaster prevention. We examined the usefulness and electric performance of the FPED excited by waves in experiments.
Elastic-Plastic Pull-In Strength and Damage Analyses of Steel Catenary Risers in Deepwater
Authors: Luk C. H. , Chang S.-H. Mark
Published: November 2011

This paper presents the strength and damage results based on elastic-plastic analysis to address the design feasibility of pulling in a steel catenary riser (SCR) through a pull tube with various bend configurations in a Spar. The example riser system contains an SCR of typical size, a tapered stress joint, a vertical pull tube with multiple bend sections, guide supports for the pull tube, and the associated pull head and pull chain connected to the top of the riser. The design methods discussed in the paper include: (1) Modeling of riser and pull tube in ABAQUS for strength analysis of the SCR; (2) Strain-based strain-life method to assess the associated fatigue damage; and (3) Strain-based Level 3B ECA design method to derive the critical surface flaw sizes for weld qualification of the SCR inside the pull tube. Comparisons are also presented between results derived from elastic and elastic-plastic analysis methods. The pull-in load on the example SCR increases with the water depth as well as the number and curvature of the bends on the pull tube. Calculated riser pull-in loads are about 11% to 51% higher than the submerged weight of the SCR. The elastic-plastic analysis shows small plastic zone and also small plastic strain on the example SCRs passing through pull tubes of a large bend radius of 125 ft. It also shows large plastic zone but small plastic strain on the SCR in a triple-bend pull tube with a small bend radius of 70 ft. The overall fatigue damage caused by cyclic plastic straining on the example SCRs due to pull in is lower than 3.3%. The allowable surface flaw sizes for the example SCRs are on the order of a × 2c = 8 × 10mm and 2.5 × 40mm for low aspect-ratio and high aspect-ratio surface flaws, respectively. Critical flaw sizes determined by Level 2A ECA are about 25% smaller than the flaw sizes based on Level 3B ECA for low aspect-ratio surface flaws. The specified maximum allowable flaw sizes are not very sensitive to the pull tube configuration and the water depth under the present study. The strength and damage analyses of SCR from other installation methods such as reeling are not included in this paper.
Comparative Strength Analysis of Aluminum Drill Pipes With Steel Connectors Assembled by Different Methods
Authors: Tikhonov Vadim , Davydov Danila , Alikin Rudolf , Gelfgat Mikhail
Published: November 2011

Aluminum alloys continue to be among the promising materials for manufacture of drill pipes and risers for deepwater and ultra-deepwater environment. Steel tool-joints attached to aluminum alloy pipes increase the number of make-ups and break-outs. Currently, aluminum drill pipes (ADP) are assembled by “cold” or “hot” methods. By the first method, the pin and box are screwed on the pipe with a “sufficiently” high specified make-up torque. By the second method, the pin and box of the tool joint are heated and screwed on the ends of the pipe without effort. After cooling, the shrinkage of the tool joint units creates a reliable permanent threaded “pipe – tool joint” connection. The first method is easier than the second one; however the comparative strength of these ADP connections has not been enough clear. The paper presents the results of comparative strength analysis of both types of connection after assembly at applying tensile load and alternating bending load. The theoretical aspect of the study includes a detailed FEA of “hot” and “cold” assembly connections at applying tensile load and alternating bending load with SCF evaluation. The experimental data are presented as the results of tensile testing of small-scale specimens, removed from different aluminum pipe sections that were heated during “hot” assembly. Finally, full-scale specimens of both types of connections were tested for tensile capacity and fatigue. The comparative strength of both types of connections is concluded.
Numerical Simulation of Moored Ship in Level Ice
Authors: Zhou Li , Su Biao , Riska Kaj , Moan Torgeir
Published: November 2011

The dynamic ice forces on a moored icebreaking tanker induced by drifting level ice were simulated with a two dimensional numerical model. Based on a heading controller which aimed to keep the hull head towards the drifting ice, ice resistance on ship was mainly estimated when taking the relative motion between the hull and ice into account. The mooring force and responses of the moored vessel were also looked into through parameter sensitivity studies with different ice thicknesses and ice drift speeds.
The Effect of the Seabed Proximity on the Hydrodynamic Forces of the Piggyback Pipeline Under Wave Action
Authors: Cheng Xiaofei , Wang Yongxue , Wang Guoyu
Published: November 2011

This paper presents experimental results for the hydrodynamic forces of the piggyback pipeline in the proximity of the seabed under regular and irregular wave action. Non-dimensional force coefficients for drag, inertia and lift are obtained based on Morison equation. The effect of the gap ratio e / D between the large pipeline and the seabed on the force coefficients of the piggyback pipeline is studied experimentally. The results indicate that the force coefficients initially decrease and then remain constant beyond e / D = 0.5.
Design and Analysis of a Rotor Blade Optimized for Extracting Energy From the Florida Current
Authors: VanZwieten James H. , Oster Carey M. , Duerr Alana E. S.
Published: November 2011

The Florida Current flowing past Southeast Florida represents an untapped renewable energy resource with a mean kinetic energy flux near its core of 2.32 kW/m2. The research presented in this paper details the hydrodynamic optimization of a three meter diameter, three-bladed rotor for an experimental research turbine. The proposed deployment site for this turbine is located 24 km off the coast of Southeast Florida in 300 m of water. At this location, thirteen months of continuous ocean current profile measurements have been collected. A genetic algorithm rotor optimization code was used to vary the geometry of the proposed rotor to maximize the average power output using the oceanographic measurements. The optimized rotor, operating in the observed flow field, is predicted to produce a mean shaft power of 7.153 kW when operating at 40 RPM. A sensitivity analysis shows that by increasing the RPM by 25% and 50%, the average power output can be increased by 3.56% and 4.99% respectively. Additionally, using a four-bladed rotor can increase the average power output by 4.22% when operating at 40 RPM.
Fracture Reliability of Jack-Up Platforms Under Extreme Environmental Loads
Authors: Shabakhty Naser
Published: November 2011

The jack-up rig is a movable offshore platform, which is basically being designed to work at any location, worldwide for given maximum water depths and sea states, combined with different sea bed conditions. Moreover the platform is often transported with the legs in fully raised position, from one offshore location to another, resulting in completely different loads on the structure. The combination of extreme environmental loads with a small crack in structural joints due to fabrication process or fatigue degradation may cause unstable crack extension and fracture failure. To calculate the failure probability through the fracture failure mode, two methods based on the failure assessment diagram of level 2 recommended by the British Standard Institute (BS7910[1]) and formulation recommended by Dijkstra et al. [2] are presented and investigated. The results of BS7910 gives the lower reliability index than the Dijkstra formulation for several secondary to yield stress ratios and service times but the maximum difference between them is restricted to 17% in the case of secondary stress to yield stress ratio equal one.
Multiaxial Fatigue Analysis on Reeled Steel Tube Umbilical
Authors: Li Qingquan , Yang Hezhen , Li Huajun
Published: November 2011

Multiaxial fatigue analysis on reeled steel tube umbilical is proposed based on finite element analysis (FEA) results. Due to the complexity of the umbilical geometry, stresses and strains field becomes multiaxial, worsening the fatigue resistance. Reel-lay method, is one of the most efficient and cost-effective methods of pipeline installation. However, if installed by reel-lay method, material properties of the umbilical change may have an influence in fatigue performance of the line. Finite element analysis is applied with contact and formulation, and the load history through reel, aligner and straightener is simulated. The strain history of the whole modeling process in critical element is given, and the properties’ change after the load history is discussed. Then, principal stress criteria and Brown–Miller criteria (both combined with critical plane approach) based on FEA results were used to do fatigue life prediction of reeled and non-reeled model, respectively. The results indicate that reel-lay method does have a great influence on the fatigue life of steel tube umbilical, so the influence of installation on the umbilical fatigue must be considered when reel-lay method is adopted.
Multiobjective Optimization for Dynamic Umbilical Installation Using Non-Dominated Sorting Genetic Algorithm
Authors: Wang Aijun , Yang Hezhen , Li Huajun
Published: November 2011

This paper presents a method of multiobjective optimization based on approximation model for dynamic umbilical installation. The optimization aims to find out the most cost effective size, quantity and location of buoyancy modules for umbilical installation. Due to the highly geometrically nonlinearity and highly responsive dynamic nature in deepwater, dynamic umbilical analysis is very complex and time-consuming. Approximation Model constructed by design of experiment (DOE) sampling is utilized to solve this problem. Non-linear dynamic analyses considering environmental loadings are executed on these sample points from DOE. Non-dominated Sorting Genetic Algorithm (NSGA-II) is employed to obtain the Pareto solution set through an evolutionary optimization process. The optimization results indicate this optimization strategy with approximation model is valid, and provide the optimal deployment way of buoyancy modules.
Model Tests for VIM of Multi-Column Floating Platforms
Authors: Magee Allan , Sheikh Rizwan , Guan Kenneth Yeoh Hock , Choo Jaime Tan Hui , Malik Adi Maimun Abdul , Abdul Ghani Mohamad Pauzi , Abyn Hassan
Published: November 2011

This paper discusses the model tests of multi-column floating platforms which are carried out at the Universiti Teknologi Malaysia Marine Laboratory in Johor Bahru state, near the southern tip of the Malaysian Peninsula. In part to enhance local capabilities for testing all types of floating platforms, Shell and Technip are jointly carrying out this research at the said facility. The objectives of these tests are to assess the effects of realistic wave and current environments on the motions of multi-column floating platforms such as TLPs and to obtain results to be used for calibrating numerical analysis models such as CFD used to calculate platform motions. A test set-up is currently being used to test a TLP for Southeast Asian environment. The important parameters to match are reduced velocities in various modes of motion and the mass ratio of the floating body. This paper presents relevant model test results available at the time of publication and compares them to existing data for other platforms. A brief description of upcoming tests and future relevant research areas are included.
Tangguh LNG Project Analysis of Full Scale Statistical Uplift Testing With Multiple Soil Layers
Authors: Griffiths Terry , Marcollo Hayden , Johnson Richard , Mariatmo Domenico
Published: November 2011

The Tangguh LNG subsea pipelines are susceptible to upheaval buckling (UHB), for which the primary mitigation was to trench and bury with quarried rock. To ensure a uniform level of reliability is achieved and also to optimise rock volumes, a full structural reliability analysis (SRA) was undertaken as an alternative to utilizing DNV-RP-F110. This paper summarises the analysis of full scale test results to evaluate uplift resistance, including the effects of thin layers of natural trench backfill, filter and armour rock layering. The testing also undertook enough tests to enable statistical measures of reliability to be found. The results of testing are compared with generic uplift models presented in DNV-RP-F110, with considerable improvements justified within well defined confidence intervals.
Assessing Hydrodynamic Behavior During Offshore Loading and Discharge in the Heavy Marine Transport
Authors: Peters O. A. J. , Huijsmans R. H. M.
Published: November 2011

Heavy Marine Transport is a well accepted method to move large heavy offshore related floating structures around the world. This type of transport is normally limited to getting from and going to sheltered locations, where loading and discharge operation of these objects are safely carried out in very mild environment. However, there is an increasing demand for loading and discharge at offshore locations; and as these operations are sensitive to environmental criteria, this has consequences for the scheduling issues. Also, with increasing size and weight of offshore structures and the desire to deliver these objects directly to remote offshore location, larger Heavy Transport Vessels are required, which may need to operate in higher sea-states than presently considered safe. These safe conditions are mainly based on long term experience. Assessment of the hydrodynamic behavior of submerged HTVs and cargo in rough seaway, in short Offshore Loading / Discharge, will contribute to extending the scope and operability of HTVs. Also, this investigation will contribute to safety by creating more insight in heavy transport operations. Research and development projects in the past have dealt with many aspects of Offshore Loading/Discharge. Both the basic design (of both HTV and systems) and hydrodynamic behavior are investigated. Problems were encountered in the area of predicting the relative behavior of floating structure above a HTV. Investigations have shown that inaccuracy is mainly caused due to the narrow gap between cargo and HTV. Development of an accurate, quick and cost-effective method for the prediction of hydrodynamic behavior of cargo floating above a HTV is in progress. This paper is presenting theory and limitations of an adapted multi-body diffraction theory. The adapted theory uses different domains in which different solution methods are used. For the flow in the gap between cargo and HTV, a 2D solution is used, whereas for the outside domain standard 3D potential solution is applied. Because of analogy with the single-body floating object in shallow water with narrow gap between body and seafloor, model tests have been performed with different shapes; these shapes are representing typical cargos. The results of the measurements for the different shapes are compared and gap flow phenomenon is explained.
HAZ Toughness: Realistic Testing for Pipeline Integrity
Authors: Amadioha Alexander U. , Bannister Adam C. , Slater Simon , Connelly Martin
Published: November 2011

Fracture toughness testing of the heat-affected zone (HAZ) of linepipe seam welds is a requirement for most pipeline projects. Occasionally, low individual values can be measured in the HAZ and these have been attributed to, among other factors, the statistical nature of the HAZ and the associated probability of encountering local brittle zones. The structural significance of these outliers has remained a subject of debate between linepipe users and manufacturers [1], especially as their low significance can be demonstrated via large-scale structurally-representative tests [2–3]. To circumvent the higher cost of such large-scale testing, constraint-corrected fracture toughness testing can be used such that the conditions in the small-scale test more closely reflect those in service. However, there is little consistency between the many test and application codes in terms of how such tests should be carried out, and what steps are required to demonstrate that the measured toughness is structurally representative. Furthermore, the level of benefit to be obtained cannot be easily predicted. In the current study, a range of fracture mechanics tests was conducted on the HAZ of the longitudinal seam weld of a grade X65 U-O-E SAW pipe. Varying degrees of constraint, scale and loading mode were evaluated to establish the characteristic toughness of the HAZ in a statistical manner, with over fifty specimens tested in total. The specimens tested included notched bend (SENB) and tension (SENT) designs as well as surface notched tension (SNT), all with varying crack depth. The range of specimen and loading types, when compared with the requirements of the various relevant standards, highlighted the contradictory nature of current standards. The toughness established for each set of specific test conditions was used in a theoretical Engineering Critical Assessment (ECA) assuming various levels of applied stress, residual stress and flaw size inputs. The wide range of conclusions that would have been reached based on the small-scale toughness tests carried out under varying levels of constraint was easily demonstrated via the ECA. The conflicting requirements of several testing and application standards for longitudinal welds should be addressed, and their consistency with current approaches for girth welds improved. The study also shows that a single-parameter fracture criterion is an insufficient indicator of real HAZ toughness and constraint (metallurgical and geometrical) level must also be considered. The use of standard deeply-notched CTOD specimens, representing high constraint, gives a highly pessimistic view of seam weld integrity, especially when subsequently combined with an ECA.
Challenging the Need for Dual Gas Production Flowline Systems Using Emerging Hydrate Remediation Intervention Technology
Authors: Sheil Henry , Young Peter
Published: November 2011

Gas production flowlines are presenting flow assurance challenges in hydrate management resulting from low ambient seawater temperatures in an increasing number of deepwater developments. During operation the equilibrium hydrate temperature of the produced fluid may be above the minimum seabed temperature, and hence there is a risk of hydrate blockage in the subsea system should the hydrate inhibition system fail. The continuous injection of MEG, with little or no insulation of the subsea system, is a common hydrate mitigation strategy for a gas production system. If insufficient inhibitor is injected there is a risk of hydrates forming and potential blockage of the pipeline in parts of the field. The industry-preferred approach for hydrate blockage remediation is Dual Sided Depressurisation (DSD). The objective is to depressurise the flowline to below hydrate onset conditions, allowing hydrate dissociation and safely disposing of the gas inventory. This is typically performed by one of two methods; installation of a dual flowline system for facility based depressurisation (with CAPEX implications); or a Mobile Offshore Drilling Unit (MODU) can be connected to an appropriate point upstream of the blockage to allow simultaneous depressurisation at the MODU and the facility (with OPEX implications). It is recognised that either method incurs significant costs. Typically the cost and time uncertainties of bringing in a MODU to solve these production stoppages is unattractive. Consequently subsea gas developments have often incurred the increased CAPEX of providing dual flowlines to permit DSD from the facility. An optimisation of the MODU-based intervention method is the subject of this paper. The feasibility of using a “lightweight” intervention vessel (for example an Offshore Support Vessel) in place of the MODU to depressurise the flowline is discussed. This paper discusses hydrate remediation difficulties and case studies; presents emerging hydrate remediation methods and briefly introduces vessel requirements. In discussing this optimisation, this paper also presents an introduction to hydrate remediation theory, some practical challenges, case studies and vessel requirements. The study concluded: • Significant CAPEX reductions may be achieved by adopting the outlined strategy; namely avoiding dual flowline infrastructure, and ensuring a reduced response time and day rate for any hydrate remediation operations to be performed. • For this strategy to be adopted cost effectively, pre-engineering, along with suitable contractual arrangements, are required to make the necessary equipment and personnel resources readily available should a hydrate blockage occur. For assets in remote locations, e.g. Australia, making the resources available is a significant challenge. • Flowline system access for depressurisation may be achieved by two methods; via the subsea Christmas tree or via suitably located fluid injection/vent access point(s).