bluuebunny/crossref_metadata_2025 huggingface dataset:
Anesthesia management with single injection paravertebral block for aorta coarctation in infant
Authors: Türköz Ayda , Balcı Sule T. , Can Güner Meltem , Ulugöl Halim , Vuran Can , Özker Emre , Türköz Rıza
Published: August 2013

Background

Thoracotomy causes severe pain in the postoperative period. Perioperative thoracic paravertebral block reduces pain score and may improve outcome after pediatric cardiac surgery. This prospective study was designed for the efficacy and duration of a single level, single injection ultrasound–guided thoracic paravertebral block (TPVB) for fifteen infants undergoing aortic coarctation repair.

Methods

After approval of the ethical committee and the relatives of the patients, 15 infants who had undergone thoracotomy were enrolled in the study. The patients received 0.5 ml·kg−1 a bolus 0.25% bupivacaine with epinephrine 1 : 200 000 at T5‐6 level after standard general anesthesia induction. Anesthesia depth with Index of Consciousness (IOC) and tissue oxygen saturation with cerebral (rSO2‐C) and somatic thoracodorsal (rSO2‐S) were monitored. Intraoperative hemodynamic and postoperative hemodynamic and pain scores were evaluated for 24 h after surgery. Face, Legs, Activity, Cry, Consolability (FLACC) score was utilized to measure postoperative pain in the intensive care unit. Rescue 0.05 mg·kg−1 IV morphine was applied to patients in whom FLACC was >3.

Results

The median age of the patients was 4.5 (1–11) months, and the median intraoperative endtidal isoflurane concentration was 0.6% (0.3–0.8). The amount of remifentanil used intraoperatively was 4.5 (2.5–14) μg·kg−1·h−1. Intraoperative heart rate and blood pressure values significantly decreased compared with values detected at 5th, 10th, and 15th min after TPVB application, after incision prior and after cross‐clamp (P < 0.01). The median time of first dose of morphine application after block was 320 (185–430) min. The median morphine consumption in 24 h was 0.16 (0.09–0.4) mg·kg−1. The median length of postoperative intensive care unit and in‐hospital stay times was 23 (1–67) h and 4 (1–10) days, respectively.

Conclusion

We believe that TPVB, as part of a balanced anesthetic and analgesic regime, provides effective pain relief in patients undergoing aortic coarctation repair.
Strategies for increasing the yield potential of cereals: case of rice as an example
Authors: Khush Gurdev S.
Published: August 2013

Rice is the most important food crop. Worldwide, more than 3.5 billion people depend upon rice for more than 20% of their calories. Global rice demand is estimated to rise from 676 million tons in 2010 to 763 million tons in 2020 and to further increase to 852 million tons in 2035. This is an overall increase of 176 million tons in the next 25 years. To meet this challenge rice production on existing land must be increased. Grain production is largely influenced by the yield potential of rice varieties. Therefore, improvement in the yield potential of rice is the major strategy to increase world rice production. Various strategies to increase the yield potential include; (1) conventional hybridization and selection, (2) ideotype breeding, (3) hybrid breeding, (4) exploitation of wild species germplasm, (5) enhancement of photosynthesis, (6) genomic approaches and (7) physiological approaches. Rice has become a model plant for genetics and breeding research. Advances in molecular biology and genomics, proteomics and metabolics have opened new avenues to apply innovative approaches to rice breeding. Molecular‐assisted selection (MAS) has become an integral component of germplasm improvement. A large number of genes/QTLs for various traits have been tagged with molecular markers to apply MAS for trait improvement. Genome sequence data have become an important source for detecting allelic variation. It is now possible to precisely understand the role of epigenetic changes in gene expression, thus understanding the stability of various stresses under changing environments. All these advances when integrated with conventional breeding will result in designer rice varieties to meet the challenges of rice food security in 21th century.
Effects of Maternal Prenatal Smoking and Birth Outcomes Extending into the Normal Range on Academic Performance in Fourth Grade in North Carolina, USA
Authors: Anthopolos Rebecca , Edwards Sharon E. , Miranda Marie Lynn
Published: August 2013

Background

Research has documented the adverse relationship of child cognitive development with maternal prenatal smoking and poor birth outcomes. The potential, however, for maternal prenatal smoking to modify the association between birth outcomes and cognitive development is unclear.

Methods

We linked statewide North Carolina birth data for non‐Hispanic white and non‐Hispanic black children to end‐of‐grade test scores in reading and mathematics at fourth grade (n = 65 677). We fit race‐stratified multilevel models of test scores regressed on maternal smoking, birth outcomes (as measured by continuous and categorical gestational age and birthweight percentile for gestational age), and their interaction, controlling for maternal‐ and child‐level socio‐economic factors.

Results

Smoking was consistently associated with decrements in test scores, and better birth outcomes were associated with improvements in test scores, even in clinically normal ranges. Test scores increased quadratically with improving birth outcomes among smoking and non‐smoking mothers. Among non‐Hispanic white children, the magnitude of the association between gestational age and test scores was larger for children whose mothers smoked during pregnancy compared with the non‐smoking group. However, among non‐Hispanic black children, birth outcomes did not appear to interact with maternal smoking on test scores.

Conclusions

Maternal prenatal smoking may interact with birth outcomes on reading and mathematics test scores, particularly among non‐Hispanic white children. Improvements in birth outcomes, even within the clinically normal range, may be associated with improved academic performance. Pregnancy‐related exposures and events exert a significant and long‐term impact on cognitive development.
Understanding the cellular mechanism of recovery from freeze–thaw injury in spinach: possible role of aquaporins, heat shock proteins, dehydrin and antioxidant system
Authors: Chen Keting , Arora Rajeev
Published: August 2013

Recovery from reversible freeze–thaw injury in plants is a critical component of ultimate frost survival. However, little is known about this aspect at the cellular level. To explore possible cellular mechanism(s) for post‐thaw recovery (REC), we used Spinacia oleracea L. cv. Bloomsdale leaves to first determine the reversible freeze–thaw injury point. Freeze (–4.5°C)–thaw‐injured tissues (32% injury vs <3% in unfrozen control) fully recovered during post‐thaw, as assessed by an ion leakage‐based method. Our data indicate that photosystem II efficiency (Fv/Fm) was compromised in injured tissues but recovered during post‐thaw. Similarly, the reactive oxygen species (O2•− and H2O2) accumulated in injured tissues but dissipated during recovery, paralleled by the repression and restoration, respectively, of activities of antioxidant enzymes, superoxide dismutase (SOD) (EC. 1.14.1.1), and catalase (CAT) (EC.1.11.1.6) and ascorbate peroxidase (APX) (EC.1.11.1.11). Restoration of CAT and APX activities during recovery was slower than SOD, concomitant with a slower depletion of H2O2 compared to O2•−. A hypothesis was also tested that the REC is accompanied by changes in the expression of water channels [aquaporines (AQPs)] likely needed for re‐absorption of thawed extracellular water. Indeed, the expression of two spinach AQPs, SoPIP2;1 and SoδTIP, was downregulated in injured tissues and restored during recovery. Additionally, a notion that molecular chaperones [heat shock protein of 70 kDa (HSP70s)] and putative membrane stabilizers [dehydrins (DHNs)] are recruited during recovery to restore cellular homeostasis was also tested. We noted that, after an initial repression in injured tissues, the expression of three HSP70s (cytosolic, endoplasmic reticulum and mitochondrial) and a spinach DHN (CAP85) was significantly restored during the REC.
Phylogeny of the Agathidiini Westwood (Coleoptera: Leiodidae) and implications for classification and contractile morphology
Authors: PARK SUN‐JAE , LESCHEN RICHARD A. B. , AHN KEE‐JEONG
Published: August 2013

A cladistic analysis of the tribe Agathidiini Westwood is presented. Agathidiines are slime mould specialists and they are hypothesized to be a monophyletic group consisting of 12 genera (Afroagathidium Angelini & Peck, Agathidium Panzer, Anisotoma Panzer, Besuchetionella Angelini & Peck, Cyrtoplastus Reitter, Decuria Miller & Wheeler, Gelae Miller & Wheeler, Liodopria Reitter, Pseudoagathidium Angelini, Sphaeroliodes Portevin, and Stetholiodes Fall), based on three synapomorphies: epipleuron present to apical third, mesoventrite without longitudinal carina and longitudinal setal lines present on the tibiae. The dataset for phylogenetic analysis comprised 72 characters representing 198 character states derived from adult morphology. These data were analysed using equal weighting and implied weighting (k = 1–6) and supported the monophyly of the tribe based on three unique characters (epipleuron present to apical third, mesoventrite without longitudinal carina, longitudinal setal lines present on tibia) and two homoplastic characters [antennomeres 7–10 (or 6–9) asymmetrical, apical shape of terminal antennomere abruptly tapered]. The topology of IW trees with k = 4–6 was identical with one of three EW trees. Decuria was sister group to the remaining agathidiine genera whereas the following groups were resolved as monophyletic: Anisotoma, Gelae + Liodopria, and Pseudoagathidium (Afroagathidium + Besuchetionella). The clade [Sphaeroliodes rufescens (Agathidium bockshini, Agathidium subcostatum)] was supported in all analyses except for the IW (k = 1) cladogram. The monophyly of Agathidium was not supported at all and was rendered paraphyletic by the placements of Sphaeroliodes, Stetholiodes and the Pseudoagathidium (Afroagathidium + Besuchetionella) clade. Sphaeroliodes is synonymized with Agathidium (syn.n.) resulting in two new combinations [A. acuminatus (Švec) and A. rufescens (Portevin)]. Contractability is a complex character composed of several morphological features that have evolved independently within the agathidiine tree. Conglobation (the ability to roll the body into a ball) has arisen at least twice in Agathidiini.
PREVALENCE OF COMPUTED TOMOGRAPHIC SUBCHONDRAL BONE LESIONS IN THE SCAPULOHUMERAL JOINT OF 32 IMMATURE DOGS WITH THORACIC LIMB LAMENESS
Authors: Lande Rachel , Reese Shona L. , Cuddy Laura C. , Berry Clifford R. , Pozzi Antonio
Published: August 2013

Osteochondrosis is a common developmental abnormality affecting the subchondral bone of immature, large breed dogs. The purpose of this retrospective study was to describe CT lesions detected in scapulohumeral joints of 32 immature dogs undergoing CT for thoracic limb lameness. Eight dogs (14 scapulohumeral joints) had arthroscopy following imaging. Thirteen dogs (19 scapulohumeral joints) were found to have CT lesions, including 10 dogs (16 scapulohumeral joints) with subchondral bone lesions and 3 dogs with enthesopathy of the supraspinatus tendon. In one dog, subchondral bone lesions appeared as large oval defects within the mid‐aspect of the glenoid cavities, bilaterally. These lesions resembled osseous cyst‐like lesions commonly identified in the horse. This is the first report of such a presentation of a subchondral bone lesion in the glenoid cavity of a dog. In all dogs, small, focal, round or linear lucent defects were visible within the cortical bone at the junction of the greater tubercle and intertubercular groove. These structures were thought to represent vascular channels. Findings from this study support the use of CT as an adjunct modality for the identification and characterization of scapulohumeral subchondral bone lesions in immature dogs with thoracic limb lameness.
Chlorophyll fluorescence imaging: a new method for rapid detection of herbicide resistance in Alopecurus myosuroides
Authors: Kaiser Y I , Menegat A , Gerhards R
Published: August 2013

Due to the steadily increasing number of putative herbicide‐resistant weed populations, the demand for rapid in‐season tests is rising. In this study, we introduce a new quantitative herbicide‐resistance test system based on chlorophyll fluorescence imaging analysis of photosynthesis‐related parameters. Susceptible and herbicide‐resistant populations of Alopecurus myosuroides (black‐grass) were cultivated in multiwell tissue culture plates containing nutrient agar and different dosages of fenoxaprop‐P‐ethyl and mesosulfuron+iodosulfuron. The maximum quantum efficiency of the PSII was measured 3 h after transplanting (HAT) and then for seven days every 24 h. Data of maximum quantum efficiency of the PSII were compared with standard whole‐plant pot tests and molecular tests for target‐site mutations. It was possible to fit dose‐response curves and calculate corresponding resistance factors for ED90 for all populations tested using the chlorophyll fluorescence imaging. It was possible to distinguish between resistant and susceptible populations. The results of the chlorophyll fluorescence imaging corresponded well with the standard whole‐plant pot tests in the glasshouse. However, populations with proved target‐site mutations did not differ from other herbicide‐resistant populations in the maximum quantum efficiency values of the PSII. We conclude that the chlorophyll fluorescence imaging provides reliable data on herbicide resistance for both modes of action tested in a shorter time and using less space, compared with standard whole‐plant pot tests in the glasshouse.
Inter‐ and intrapopulation variation in dormancy of Oryza sativa (weedy red rice) and allelic variation in dormancy‐linked loci
Authors: Tseng T M , Burgos N R , Shivrain V K , Alcober E A , Mauromoustakos A
Published: August 2013

Oryza sativa (weedy red rice), the same species as cultivated rice, is a serious problem in rice production worldwide. Seed dormancy contributes to its persistence. We determined the effect of germination temperature and after‐ripening period on germination capacity (GC) of red rice seeds from Arkansas rice fields in three production zones. We also determined the gene diversity (GD) of dormancy‐linked loci among selected populations. The germination behaviour was evaluated at three temperatures (1°C, 15°C and 35°C) and four after‐ripening periods (0, 30, 60 and 90 days) in two independent experiments. Germination response to temperature and after‐ripening time differed among and within populations in each production zone. Overall, populations from the Delta and Grand Prairie were more dormant than those from White River. Regardless of ecotype or production zone, incubation at 35°C (mean GC = 84–100%) favoured the germination of seeds after‐ripened for 60 days. Germination of these seeds was most variable at suboptimal temperature (15°C), with mean GC ranging from 44 to 97%; at 1°C, none of the seeds germinated. Primary dormancy was released in the majority of populations after 90 days of after‐ripening. Blackhull populations generally had lower mean GC than strawhull populations, regardless of temperature, and required longer after‐ripening time to release dormancy. They also showed a higher inter‐ and intrapopulation variation in germination and after‐ripening than strawhulls and had the highest gene diversity (GD = 0.55–0.58) among test populations. Non‐dormant strawhulls were most distant (D = 0.63) from dormant blackhulls. Ecotype influenced genotypic clustering more than the dormancy trait.
Akawaio penak, a new genus and species of Neotropical electric fish (Gymnotiformes, Hypopomidae) endemic to the upper Mazaruni River in the Guiana Shield
Authors: Maldonado‐Ocampo Javier A. , López‐Fernández Hernán , Taphorn Donald C. , Bernard Calvin R. , Crampton William G. R. , Lovejoy Nathan R.
Published: August 2013

Akawaio penak, a new genus and species, is described from the upper Mazaruni River, Guyana. The new species is diagnosed from all other species of Hypopomidae by several anatomical traits. The phylogenetic affinities of the new genus were inferred using data from one nuclear (rag2) and two mitochondrial (COI and cyt b) genes. The phylogenetic analyses indicate that Akawaio is the sister taxon of a clade that includes Brachyhypopomus, Hypopomus, Microsternarchus and Racenisia. These results provide evidence for the phylogenetic composition of Hypopomidae supported by previous molecular studies and support the position of the Steatogenini (Hypopygus + Steatogenys) as the sister group of Rhamphichthys + Gymnorhamphichthys. The description of this new electric knifefish increases the total number of endemic genera and species in the upper Mazaruni, a region that is suffering freshwater habitat degradation as consequence of gold‐mining activities.
Efficiency Mapping for a Linear Hydraulic-Actuator
Authors: Manring Noah D.
Published: August 2013

This research is aimed at generating an efficiency map for a linear hydraulic-actuator that is controlled using an open-centered 4-way valve. Using the basic configuration of a double rod, double-acting linear actuator, equations for describing the input and output power of the actuator are written and nondimensionalized to produce a nondimensional map for the efficiency of the actuator itself. In conclusion, the actuator is shown to operate below a wide open valve (WOV) line with efficiencies that are typically less than 50%. Note that the WOV line describes the maximum actuator-force that may be achieved at a given actuator-velocity. While the actuator chosen for this paper is common, extensions of the methods used in this study may be applied to double-acting, single-rod designs or single-acting, single-rod designs. Furthermore, it is anticipated that this type of analysis may also be used to study the effects of power regenerating valves and for predicting the efficiency improvements that may be gained for linear hydraulic-actuators that use this type of valve design.
Plasticity and Fracture Modeling/Experimental Study of a Porous Metal Under Various Strain Rates, Temperatures, and Stress States
Authors: Allison P. G. , Grewal H. , Hammi Y. , Brown H. R. , Whittington W. R. , Horstemeyer M. F.
Published: August 2013

A microstructure-based internal state variable (ISV) plasticity-damage model was used to model the mechanical behavior of a porous FC-0205 steel alloy that was procured via a powder metal (PM) process. Because the porosity was very high and the nearest neighbor distance (NND) for the pores was close, a new pore coalescence ISV equation was introduced that allows for enhanced pore growth from the concentrated pores. This coalescence equation effectively includes the local stress interaction within the interpore ligament distance between pores and is physically motivated with these highly porous powder metals. Monotonic tension, compression, and torsion tests were performed at various porosity levels and temperatures to obtain the set of plasticity and damage constants required for model calibration. Once the model calibration was achieved, then tension tests on two different notch radii Bridgman specimens were undertaken to study the damage-triaxiality dependence for model validation. Fracture surface analysis was performed using scanning electron microscopy (SEM) to quantify the pore sizes of the different specimens. The validated model was then used to predict the component performance of an automotive PM bearing cap. Although the microstructure-sensitive ISV model has been employed for this particular FC-0205 steel, the model is general enough to be applied to other metal alloys as well.
Probabilistic Inverse Simulation and Its Application in Vehicle Accident Reconstruction
Authors: Zhang Xiaoyun , Hu Zhen , Du Xiaoping
Published: August 2013

Inverse simulation is an inverse process of direct simulation. It determines unknown input variables of the direct simulation for a given set of simulation output variables. Uncertainties usually exist, making it difficult to solve inverse simulation problems. The objective of this research is to account for uncertainties in inverse simulation in order to produce high confidence in simulation results. The major approach is the use of the maximum probability density function (PDF), which determines not only unknown deterministic input variables but also the realizations of random input variables. Both types of variables are solved on the condition that the joint probability density of all the random variables is maximum. The proposed methodology is applied to a traffic accident reconstruction problem where the simulation output (accident consequences) is known and the simulation input (velocities of the vehicle at the beginning of crash) is sought.
Crack Growth Testing of an X80 Pipeline Girth Weld Using SE(T) and SE(B) Fracture Specimens
Authors: Mathias Leonardo L. S. , Burgos Diego F. S. , Donato Gustavo H. B. , Paredes Marcelo , Ruggieri Claudio
Published: August 2013

Accurate measurements of fracture resistance properties, including crack growth resistance curves for pipeline girth welds, become essential in defect assessment procedures of the weldment region and the heat affected zone, where undetected cracklike defects (such as lack of penetration, deep undercuts, root cracks, etc.) may further extend due to to high tension stresses and strains. This work presents an investigation of the ductile tearing properties for a girth weld made of an API 5L X80 pipeline steel using experimentally measured crack growth resistance curves ((J-Δa curves). Use of these materials is motivated by the increasing demand in the number of applications for manufacturing high strength pipes for the oil and gas industry including marine applications and steel catenary risers. Testing of the pipeline girth welds utilized side-grooved, clamped single edge notched tensiles (SE (T)) specimens and three-point (3P) bend single edge bend (SE(B)) specimens with a weld centerline notch to determine the crack growth resistance curves based upon the unloading compliance (UC) method using a single specimen technique. Recently developed compliance functions and η-factors applicable for SE (T) and SE(B) fracture specimens with homogeneous material and overmatch welds are introduced to determine crack growth resistance data from laboratory measurements of load-displacement records. This experimental characterization provides additional toughness data which serve to evaluate crack growth resistance properties of pipeline girth welds using SE (T) and SE(B) specimens with weld centerline cracks.
Comparison of Two Base-Potentials for a Slender-Body Method
Authors: Alidadi Mahmoud , Calisal Sander
Published: August 2013

The effects of two base-potentials on the accuracy of a slender-body method are studied in this paper. In the formulation for this method which is developed for the slender ships, the velocity potential is decomposed into a base-potential and a perturbation potential. Then using an order of magnitude analysis, the three-dimensional flow problem is simplified into a series of two-dimensional problems for the perturbation potential. These two-dimensional problems are solved with the linearized free surface boundary conditions, using a mixed Eulerian-Lagrangian method. Finally for the two base-potentials, the numerical wave elevation along a Wigleyull are compared with the experimental results.
Effects of Viscosity and Free-Surface Nonlinearity on the Wave Motion Generated by an Oscillating Twin Hull
Authors: Ananthakrishnan Palaniswamy
Published: August 2013

The hydrodynamics of a rectangular, floating twin hull under heave oscillation is analyzed to determine viscous and nonlinear effects on the radiation hydrodynamics of multi-hulls, in particular, at the resonant frequency corresponding to the piston (Helmholtz) mode of wave motions. A second-order finite-difference method based on boundary-fitted coordinates is used for the solution of the incompressible Navier-Stokes equations together with exact nonlinear viscous boundary conditions. To separate the viscosity effects from the nonlinear free-surface effects, through comparison of results, nonlinear inviscid results are also obtained using a boundary-fitted curvilinear coordinates based finite difference method. The nonlinear inviscid algorithm is based on the Eulerian-Lagrangian formulation of the nonlinear free-surface flow. The nonlinear results are compared with the linear potential-flow results obtained by Yeung and Seah [20] to quantify the combined nonlinear and viscous effects on the wave forces. The present results show the overall behavior of the wave motion to be similar to that predicted by the linear potential-flow theory [20]. Our results show that the effects of nonlinearity and viscosity on the wave motion can be significant for the Helmholtz mode, particularly for small separation distance between the hulls, which result in large vertical oscillation of the mean surface between the hulls. For small amplitudes of oscillation, the hydrodynamic pressure forces computed in the present analysis are in striking agreement with that given by the linear potential-flow analysis of Yeung and Seah [20].
In-Service Fatigue Performance of SCR Girth Welds Installed by Reeling
Authors: Darcis Philippe P. , Aguilar Eduardo , Erezuma Emma , Marines-Garcia Israel , Ruiz Eduardo A. , Quintanilla Hector M.
Published: August 2013

Interest arises on verifying the SCR girth welds fatigue response to a more representative loading spectrum of the actual in-service conditions and after reel-lay deformation. It is important to determine if the actual riser component’s qualification, without pre-straining and under constant amplitude loading, evidences discrepancies with in-service conditions, in terms of fatigue strength.

This situation has motivated the full scale S-N fatigue performance evaluation of SCR girth welds under constant and variable amplitude loading, and after reel-lay simulations. A CMn steel X65 pipe 10.75” outside diameter (OD) and 25.4 mm wall thickness (WT) was chosen for this program. The Welding Procedure developed for girth welds manufacturing involved the use of the Lincoln STT® process for the root pass and the GMAW process for the fill and cap passes. Reeling trials were performed at Stress Engineering Services, Houston, U.S.A.. A dedicated commercial software was used to simulate the variable amplitude loading spectrum, which is representative of a SCR Touch Down Point (TDP) in West of Africa at a water depth of 1,200 m (3937 ft) and a FPSO as production platform.

The experimental approach was focused on estimating the damage introduced by reeling and by loading cycles of various magnitudes in the riser service time history. Results of strained and unstrained specimens, tested at constant and variable amplitude, have been compared, and the cumulative damage rule typically used by Riser fatigue designers has been evaluated (i.e. Miner’s linear cumulative damage rule). Systematic fractographic investigations were performed on all the samples after testing to identify their fatigue failure initiation causes.
Mesoscale Modeling of Non-Isothermal Fluid Displacement in Capillary Tube Using Dissipative Particle Dynamics
Authors: Zaman M. S. , Satish M. G.
Published: August 2013

It is crucial to understand how one fluid is displaced by another at different temperature through a capillary, as many industrial and reservoir enhanced recovery methods fall into this category. Dissipative particle dynamics (DPD) method has been successfully applied to model mesoscale behaviors of many processes. In this paper, DPD method with energy conservation has been applied to model non-isothermal fluid displacement in capillary tube. Validation of the in-house computer code written in C# is carried out by modeling isothermal no-slip fluid flow. Simulation of non-isothermal fluid displacement using energy conserving DPD gives insight about the parameters affecting the flow.
Iceberg Shape Sensitivity in Ship Impact Assessment in View of Existing Material Models
Authors: Storheim Martin , Kim Ekaterina , Amdahl Jørgen , Ehlers Sören
Published: August 2013

Large natural resources in the Arctic region will in the coming years require significant shipping activity within and through the Arctic region. When operating in Arctic open water, there is a significant risk of high-energy encounters with smaller ice masses like bergy bits and growlers. Consequently, there is a need to assess the structural response to high energy encounters in ice-infested waters. Experimental data of high energy ice impact are scarce, and numerical models could be used as a tool to provide insight into the possible physical processes and to their structural implications. This paper focuses on impact with small icebergs and bergy bits.

In order to rely on the numerical results, it is necessary to have a good understanding of the physical parameters describing the iceberg interaction. Icebergs are in general inhomogeneous with properties dependent among other on temperature, grain size, strain rate, shape and imperfections. Ice crushing is a complicated process involving fracture, melting, high confinement and high pressures. This necessitates significant simplifications in the material modeling. For engineering purposes a representative load model is applied rather than a physically correct ice material model.

The local shape dependency of iceberg interaction is investigated by existing representative load material models. For blunt objects and moderate deformations the models agree well, and show a similar range of energy vs. hull deformation. For sharper objects the material models disagree quite strongly. The material model from Liu et.al (2011) crush the ice easily, whereas the models from Gagnon (2007) and Gagnon (2011) both penetrate the hull. From a physical perspective, a sharp ice edge should crush initially until sufficient force is mobilized to deform the vessel hull. Which ice features that will crush or penetrate is important to know in order to efficiently design against iceberg impact.

Further work is needed to assess the energy dissipation in ice during crushing, especially for sharp features. This will enable the material models to be calibrated towards an energy criterion, and yield more coherent results. At the moment it is difficult to conclude if any of the ice models behave in a physically acceptable manner based on the structural deformation. Consequently, it is premature to conclude in a design situation as to which local ice shapes are important to design against.
Towards Fully Non-Linear Floating Body Simulations by a Potential Method
Authors: Söding Heinrich
Published: August 2013

A 3-dimensional Rankine source panel method for simulating a rigid floating body in steep waves is being developed. The aim is to obtain the same quality as free-surface RANSE methods, which are well suited for this application, but to require only a small fraction of the computing time needed by RANSE methods. The body may have forward speed or perform maneuvering motions. The exact boundary conditions are satisfied at the actual location of the fluid boundaries. The waves are generated not by a material wave maker, but by an approximate wave potential which needs not satisfy the exact free-surface condition. No wave damping regions are required. Whereas for steep waves without a body the method appears satisfactory, it needs further improvements if a body is present.
An Optimum Design Concept for Offshore Cage Culture
Authors: Shainee Mohamed , Leira Bernt J. , Ellingsen Harald , Fredheim Arne
Published: August 2013

There is an overwhelming support to move aquaculture cages into offshore waters. Some of the key drivers for moving into offshore waters are limitation of available space near the coast, conflicts within as well as other coastal users, prospect of limitless expansion in offshore sites, the potential for optimum growth conditions and the need to reduce the production cost by increasing the scale of operation. Therefore, by using a set of requirements derived earlier by the authors, the paper looks into the current offshore cage designing concepts in order to propose an optimum design concept for offshore aquaculture. With the help of an expert panel, representing various disciplines which are important for fish farm development, the assessment point towards a single point mooring cage concept as the best option for offshore aquaculture farming. This concept is demonstrated by the use of simple geometric relations and graphs, showing the relation between the total horizontal forces, FH, vertical force component, FV, as the cage submerge. While the contribution from the current, FHC, to the total horizontal force, FH, is kept constant, the contribution from the waves to the total horizontal force, FH, (as assumed to be 33%) is subjected to a reduction proportional to the factor e2kz, representing the reduction in water particle velocity as a function of depth. Further, in light of the requirements derived through the major stakeholders, this paper also propose an alternative classification of cages into two major categories, i.e. systems that are intended to resist and dissipate environmental forces and system that are designed to avoid environmental forces.
Comparison of Physical Model Tests With a Time Domain Simulation Model of a Wave Energy Converter
Authors: Nicoll Ryan S. , Wood Charles F. , Roy André R.
Published: August 2013

Development of wave energy conversion systems may yield many key benefits for society such as the production of electrical power or fresh water for remote communities. However, complex ocean dynamics make it difficult for technology developers to not only address the stability and survivability of their systems, but also to establish energy conversion rates that are fundamental to proving economic viability. Building physical prototypes presents many challenges in terms of cost, accessible facilities, and time requirements. The use of accurate numerical modelling and computer simulation can help guide design and significantly reduce the number of physical prototype tests required and as a result play a primary role in the development of wave energy conversion systems that have to operate in challenging marine environments.

SurfPower is an ocean wave energy converter (WEC) that converts wave motion into useful energy through surge and heave motion of a point absorber. The system pumps seawater into a high pressure hydraulic network that generates electricity via a turbine or freshwater via desalination at a facility onshore. The system is nonlinear due to the significant change in draft and mooring reaction load through the energy capture cycle of the device. This makes the use of nonlinear time domain simulation ideal for analysis and design of the system. Furthermore, utilizing a simplified nonlinear hydrodynamic model available in the time domain results in a practical early-stage design tool for system refinement.

The focus of this work is to compare the results of scale model testing completed at the Institute for Ocean Technology in St. John’s, Newfoundland, with results produced from an equivalent system simulated in the time domain simulation software ProteusDS. The results give an assessment of the range of error that can be used to assess other experiments of the SurfPower WEC at full scale.
Three-Dimensional Effects of the Flow Normal to a Flat Plate at a High Reynolds Number
Authors: Tian Xinliang , Ong Muk Chen , Yang Jianmin , Myrhaug Dag , Chen Gang
Published: August 2013

Plate components are often found in offshore and marine structures, such as heave damping plates in spar platform and bilge keels in ships. Two-dimensional (2D) and three-dimensional (3D) numerical simulations are performed to investigate the 3D effects of the flow normal to a flat plate at a high Reynolds number (Re = 1:5×105, based on the height of the plate and the free stream velocity). The ratio of the plate thickness to the plate height is 0.02. The 2D simulations are carried out by solving the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with the k-ω Shear Stress Transport (SST) turbulence model, while the 3D simulations are carried out with the large-eddy simulation (LES) method. The hydrodynamic results (such as time-averaged drag coefficient, Strouhal number and mean recirculation length) are compared with the published experimental data. The near-wake flow structures are also discussed. The 3D simulation results are in good agreement with the published experimental data; however, the 2D simulations show a poor comparison with the experimental data. This shows that the 3D effects are important for the high Reynolds number flow normal to a flat plate.
Vibration Survey of Topsides Piping on a Producing FPSO in the Gulf of Guinea
Authors: Ochonogor Chukwuma , Madawaki Isah , Anaturk Ali , Eijk André , Slis Erik , Schoonewille Harm
Published: August 2013

Visible mechanical vibrations were noticed on two topsides piping systems on a producing FPSO, in the Gulf of Guinea following increased production in 2008 and 2009. A field survey was undertaken on the piping of the FPSO to investigate the actual pulsation and vibration levels followed by a computer analysis to investigate if fatigue failure, caused by the actual vibrations as measured, would occur. Vibration data was collected from subsea jumpers, risers and topsides piping to ensure full coverage of the flow line systems from the wellhead to production manifolds on the topsides. The objectives of the study were to: determine the root cause of the vibrations, ascertain the vibration levels, predict fatigue occurrence and reduce vibration to acceptable levels. The study revealed that the maximum vibrations levels were caused as a result of an excitation of several mechanical natural frequencies by a broadband excitation as a result of the multiphase flow. The measured vibration levels exceeded the allowable levels in some points of the pipe system which was caused by a very flexible supporting layout. The results of the analysis showed that fatigue failure of the main piping would not occur. However, to avoid failure of small branch connections (e.g. pressure and temperature transmitters) and valves, modifications e.g. additional supports and stiffening of structural steel members, have been advised to achieve acceptable vibration levels to ensure a safe and reliable system in the long term. The measurements, data processing, analysis results and recommendations are discussed in detail.
A Review of Numerical Modelling of Wave Energy Converter Arrays
Authors: Folley Matt , Babarit Aurélien , Child Ben , Forehand David , O’Boyle Louise , Silverthorne Katie , Spinneken Johannes , Stratigaki Vasiliki , Troch Peter
Published: August 2013

Large-scale commercial exploitation of wave energy is certain to require the deployment of wave energy converters (WECs) in arrays, creating ‘WEC farms’. An understanding of the hydrodynamic interactions in such arrays is essential for determining optimum layouts of WECs, as well as calculating the area of ocean that the farms will require. It is equally important to consider the potential impact of wave farms on the local and distal wave climates and coastal processes; a poor understanding of the resulting environmental impact may hamper progress, as it would make planning consents more difficult to obtain. It is therefore clear that an understanding the interactions between WECs within a farm is vital for the continued development of the wave energy industry.

To support WEC farm design, a range of different numerical models have been developed, with both wave phase-resolving and wave phase-averaging models now available. Phase-resolving methods are primarily based on potential flow models and include semi-analytical techniques, boundary element methods and methods involving the mild-slope equations. Phase-averaging methods are all based around spectral wave models, with supra-grid and sub-grid wave farm models available as alternative implementations.

The aims, underlying principles, strengths, weaknesses and obtained results of the main numerical methods currently used for modelling wave energy converter arrays are described in this paper, using a common framework. This allows a qualitative comparative analysis of the different methods to be performed at the end of the paper. This includes consideration of the conditions under which the models may be applied, the output of the models and the relationship between array size and computational effort. Guidance for developers is also presented on the most suitable numerical method to use for given aspects of WEC farm design. For instance, certain models are more suitable for studying near-field effects, whilst others are preferable for investigating far-field effects of the WEC farms. Furthermore, the analysis presented in this paper identifies areas in which the numerical modelling of WEC arrays is relatively weak and thus highlights those in which future developments are required.
Wave Data Assimilation Using Support Vector Regression (SVR) Model and Ensemble Kalman Filter (EnKF)
Authors: Golestani Maziar , Zeinoddini Mostafa
Published: August 2013

The prediction of wind driven ocean waves is of primary importance for the safety of shipping and off-shore operations, as well as for scientific studies of, e.g., sediment transport and ocean-atmosphere interaction. Traditionally, wave models do not explicitly use the wave observations to estimate the present sea state: the only input to the models is a sequence of wind fields from a meteorological model. However, it is obvious that the model estimate of both the present and the future sea state can be improved if all available knowledge is combined, which can be done by assimilation of the observations into the model. In the present study a new approach for assimilating wave measurements is presented. A soft computing method namely Support Vector Regression (SVR) is used as a surrogate model to simulate wave heights. This model is trained with a data set of wind and wave measurements and is capable of predicting wave characteristics with relatively good quality. In the other hand, swells and short duration storms cannot be well modeled by the SVR model. Therefore assimilating the wave height measurements into the SVR model using an Ensemble Kalman Filter (EnKF) was utilized to ensure better efficiency of the model. A pretty complicated Matlab and Shell scripts were modified in order to establish appropriate data assimilation (DA) system. Using two data sets from NDBC buoys in different geographical zones and performing statistical comparisons showed that the assimilation scheme can reduce the errors in predicting swells, storm peaks and also the storm duration and time. Also it was seen that the combination of SVR model and the EnKF method can be easily used for producing high quality wave forecasts.
Girth Welding Development of Heavy Wall Materials for Severe Applications
Authors: Mota-Solis Noé , Pelcastre Mauricio , Ruiz Eduardo , Darcis Philippe , Garcia-Gonzalez Jose Enrique , Quintanilla Hector
Published: August 2013

The needs for oil and gas exploration in deep water (DW) and ultra-deep water (UDW) severe environments involve critical requirements of heavy wall materials. Offshore DW and UDW impose demanding service conditions of sour environment, mechanical properties, fatigue performance, gas service, high pressure and wide temperature ranges not only for heavy wall seamless line pipe materials but also for the girth weld performance. Thus, the development of heavy wall materials for severe applications is essential for DW and UDW, where complex material requirements are sought. Additionally the girth welding of heavy wall materials has imposed particularities typical of large wall thickness materials’ welding. The latter requires the development of particular solutions for pre-production and GMAW narrow groove offshore welding procedures.

The present work presents the development of two welding processes of a heavy wall seamless pipe material: 273.1 mm OD × 46 mm WT, X65 steel grade. Pre-production welding involves STT®+SAW using a dual slope V-bevel, filler material for root processing was an AWS ER80S-G, while welding deposition for fill and cap passes was made using twin-wire technique, with two different electrodes (ENi1K and EG AWS designations), in combination with a neutral flux. On the other hand, narrow groove welding procedure considered a J-bevel, 3° angle, applying STT®+GMAW; filler material for GMAW was as well an ER80S-G AWS designation. Both welding procedures are aimed to deliver adequate mechanical properties to meet sour-service requirements (<250HV10), weld metal overmatching (120 MPa minimum) and toughness (CVN 45JAVE/38JIND) at low temperature. Mechanical characterization included hardness Vickers measurements using a 10 kgf load, tensile tests in all-weld metal and transverse impact fracture Charpy V-notch tests and CTOD tests.
Lattice Boltzmann Simulation of Miscible Fluids Displacement in the Pore Space
Authors: Liang Yiqiang , Song Yongchen , Li Weizhong
Published: August 2013

In this work, we simulate natural miscible process and miscible fluids displacement in pore space by using lattice-Boltzmann method. In the natural miscible case, the results including concentration profile and thickness of miscible zone agree well with analytical solutions, which verifies the model’s reliability and veracity. The viscosity ratio is also taken into account to study its influence on the miscible process. Furthermore, we apply pressure boundary at inlet and outlet of the channel to study the displacement of miscible fluids. The whole process, in general, is divided into three phases: fluid flow rate increasing driven by pressure gradient, transitional period, and relatively stable stage. And we carefully give each phase explanations of physical mechanisms. The numerical results provide a good understanding of the mechanisms of miscible fluids displacement and confirm that the LBM can be a promising tool for investigating miscible fluids behavior.
Understanding the intentional acoustic behavior of humpback whales: A production-based approach
Authors: Cazau Dorian , Adam Olivier , Laitman Jeffrey T. , Reidenberg Joy S.
Published: August 2013

Following a production-based approach, this paper deals with the acoustic behavior of humpback whales. This approach investigates various physical factors, which are either internal (e.g., physiological mechanisms) or external (e.g., environmental constraints) to the respiratory tractus of the whale, for their implications in sound production. This paper aims to describe a functional scenario of this tractus for the generation of vocal sounds. To do so, a division of this tractus into three different configurations is proposed, based on the air recirculation process which determines air sources and laryngeal valves. Then, assuming a vocal function (in sound generation or modification) for several specific anatomical components, an acoustic characterization of each of these configurations is proposed to link different spectral features, namely, fundamental frequencies and formant structures, to specific vocal production mechanisms. A discussion around the question of whether the whale is able to fully exploit the acoustic potential of its respiratory tractus is eventually provided.