bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonant Generation of Internal Waves on Two Muddy Sea Beds by a Progressive Surface Wave
Authors: Yang Ray-Yeng , Hwung Hwung-Hweng , Shugan Igor V.
Published: February 2010

The present work is motivated by recent studies on the interaction between a progressive surface wave and the nearly standing subharmonic internal waves in a two-layer system. It is well known that the loading of progressive surface waves, a silty sediment bed was repeatedly and extensively fluidized. The great interest in understanding this phenomenon was induced by the practical applications in sediment transport, wave attenuation, and the design of marine structures. The nonlinear response of an initially flat sea bed, with two muddy sections, to a monochromatic surface progressive wave was investigated in the present study. Based on an analysis similar to that of Hill & Foda’s (1998), the multiple scale perturbation method was adopted and the boundary value problem was expanded in a power series of the surface-wave steepness. The linear harmonics and the conditions for resonance were obtained by the leading order. While, the temporal evolution equations for the internal-wave amplitudes were investigated by a second-order analysis. It was found that result for equal density of two muddy sections is similar to that of Hill & Foda’s (1998). Two opposite-traveling internal “mud” waves are selectively excited and formed a resonant triad with the progressive surface wave. However for a surface water wave progressing over two different muddy sections, the surface wave will also excite only two opposite-traveling short interfacial waves, forming a nearly standing wave at the interface of the fresh water and the muddy layer. Meanwhile, two opposite-outgoing “mud” waves each with very long wavelength will be simultaneously induced at the interface of two muddy sections. As a result, the amplitudes of the two short internal waves are found to grow exponentially in time. Furthermore, it will be much difficult to excite the internal waves when surface water wave progressing over two muddy sections with the large density gap.
Higher-Order Modeling of Water Waves Generated by Submerged Moving Disturbances
Authors: Zhou Hongqiang , Teng Michelle H.
Published: February 2010

In this paper, a recently derived (Zhou, 2008) fully nonlinear and higher-order dispersive Boussinesq-type model for wave generation and propagation is presented. This new model is an extension of the wave propagation model by Gobbi and Kirby (1999) and Gobbi et al. (2000) to include the time-varying seabed bathymetry. The resulting new version retains the 4th-order approximation of the dispersion relation and the velocity distribution in the vertical direction, and extends the application to both water wave propagation and wave generation by seabed disturbances such as submarine landslides. The model equations are solved numerically through a higher-order finite difference scheme. To examine the validity of the new model and the improvement due to the higher-order extensions, numerical simulations of two wave generation cases are carried out based on the new 4th order model and an existing lower order Boussinesq model. The results show that the higher order model provides the more accurate prediction for the generated waves, especially those in the trailing region of shorter wavelengths where the traditional lower order Boussinesq model becomes much less accurate.
Experimental Study of a Straight-Bladed Vertical Axis Wind Turbine With a Directed Guide Vane Row
Authors: Takao Manabu , Takita Hiroyuki , Saito Yohei , Maeda Takao , Kamada Yasunari , Toshimitsu Kazuhiko
Published: February 2010

The objective of this study is to show the effect of guide vane geometry on the performance of wind turbine. In order to overcome the disadvantages of vertical axis wind turbine, a straight-bladed vertical axis wind turbine (S-VAWT) with a directed guide vane row has been proposed and tested by the authors. According to previous studies, it was clarified that the performance of the turbine can be improved by means of the directed guide vane row. However, the guide vane geometry of S-VAWT has not been optimized so far. In order to clarify the effect of guide vane geometry, the effects of distance between the guide vanes and the number of guide vanes on power and torque coefficients were investigated in the experiments. The experimental study was carried out by a wind tunnel. The wind tunnel with a diameter of 1.8m is open jet type. The wind velocity is from 5 to 9 m/s in the experiments. The rotor has three straight blades with a profile of NACA4518 and a chord length of 100 mm, a diameter of 0.6 m and a blade height of 0.7 m. The guide vane row consists of some arc plates.
Vortex Pattern Comparison for Periodic and Harmonic Combined Cross-Flow and In-Line Forced Oscillations
Authors: Soni Prashant K. , Larsen Carl M.
Published: February 2010

For prediction of vortex-induced vibrations (VIV) the empirical models apply hydrodynamic coefficients to represent the fluid forces on the slender structures. The coefficients are in most cases found by measuring forces on a rigid cylinder under harmonic pure in-line (IL) or pure cross-flow (CF) forced motions, and are generally presented as functions of non-dimensional motion amplitude and frequency. The objective of the present work has been to find hydrodynamic coefficients for realistic combinations of CF and IL motions. Such trajectories were found from measured VIV of a flexible beam, and then used as forced motions of a rigid cylinder in uniform flow. Hydrodynamic forces were measured and used for calculation of hydrodynamic coefficients. The diameter of the rigid cylinder was larger than for the flexible beam in order to obtain optimum conditions for both experiments. However, both Reynolds number and non-dimensional frequency were identical for the two test types. The flexible beam oscillations were not perfectly periodic, but close to. More than one periodic trajectory could hence be identified as representative for the observed response, and these were used as forced motions in order to study the variability of the hydrodynamic coefficients. Alternative harmonic loops were also constructed in order to investigate the potential for using coefficients from harmonic tests as basis for empirical models. The vortex shedding process behind the cylinder has been mapped using Particle Image Velocimetry (PIV). PIV planes can picture the difference in cylinder wake for these trajectories and thus help to understand the process. The vorticity patterns at instantaneous positions for both periodic and harmonic trajectories are obtained. The vortices were mapped and the forces were measured simultaneously. Higher order harmonic components of the force are seen for all types of trajectories, and a correlation between these components and the vortex shedding pattern is observed.
Impulsive Loads on Interconnected Floating Bodies
Authors: Martinelli Luca , Ruol Piero , Zanuttigh Barbara
Published: February 2010

Aim of this contribution is to examine the load on the mooring and on the tie rods of a set of interconnected floating bodies under extreme waves, with particular attention to the layout obliquity. Tests carried out at the IMAGE department of Padova University are briefly presented. It is doubtful how to scale the laboratory tests in the presence of impulsive loads on semi-taught moorings. In order to find proper scaling laws, a numerical model is presented where the chain and the floating body are studied as a lumped mass system. Results, compared to available laboratory tests are encouraging and it appears that the main processes in presence of impulses are correctly represented by the model. Model calibration will be carried out shortly, on the basis of specific ongoing tests on floating Wave Energy Converters.
Numerical Study of the Motions in Shallow Water Waves of Floating Bodies Elastically Linked to Bottom
Authors: Tsukamoto Marcio Michiharu , Cheng Liang-Yee , Nishimoto Kazuo
Published: February 2010

The motion of floating bodies linked elastically to the bottom of seas and waterways is of great interest in the analysis of the wave suppressing devices, such as wave breakers, and the behaviors of the floating structures, such as buoys and tension leg platforms (TLP). For the modeling of the dynamics, the coupling between the hydrodynamic loads due to waves and the restoring forces due to the elastic link must be considered. In some simpler cases, the analytical approaches are available. However, in case of large amplitude waves and floating bodies with complex geometries, the analytical solutions do not give accurate results. In the present study, a numerical model based on MPS (moving particle semi-implicit method) for the hydrodynamic loads coupled with the Hook’s Law for the restoring force is adopted to analyze the motion of floating bodies with one or several elastic links to the bottom of shallow water under large amplitude waves. Initially, the results of 2D numerical simulation of simple oscillating buoys are compared with the analytical and experimental ones to validate the numerical approach. After that, the approach is applied to the study of the shallow water wave supressing devices. Heave, surge and pitching motions of the floaters are assessed as well as the hydrodynamic coefficients to show the effect of the elastic links in the nonlinear wave hydrodynamics.
A Phase-Amplitude Iteration Scheme for the Optimization of Deterministic Wave Sequences
Authors: Schmittner Christian , Kosleck Sascha , Hennig Janou
Published: February 2010

For the deterministic investigation of extreme events like capsizing, broaching or wave impacts, methods for the generation of deterministic wave sequences are required. These wave sequences can be derived from full scale measurements, numerical simulations or other sources. Most methods for the generation of deterministic wave sequences rely as a backbone on linear wave theory for the backwards transformation of the wave train from the target position in the wave basin to the position of the wave maker. This implies that nonlinear wave effects are not covered to full extend or they are completely neglected. This paper presents a method to improve the quality of the generated wave train via an experimental optimization. Based on a first wave sequence generated with linear wave theory and measured in the wave basin, the phases and amplitudes of the wave maker control signal are modified in frequency domain. The iteration scheme corrects both, shifts in time and in location, resulting in an improved deterministic wave train at the target location. The paper includes results of this method from three different basins with different types of wave generators, water depth and model scales. In addition, this method is applied to a numerical wave tank where the waves can be optimized before the actual basin testing.
Techniques for Fracture Toughness Testing of Offshore Pipelines
Authors: Fonzo Andrea , Melis Giorgio , Di Vito Luigi , Mannucci Gianluca , Darcis Philippe , Richard Gilles , Quintanilla Hector , Armengol Mariano
Published: February 2010

The need to evaluate the significance of flaws in welded pipelines for gas transportation requires the knowledge of the material resistance to ductile tearing. In particular, the fracture resistance of pipe girth welds should be evaluated since they may potentially be critical for structural integrity. Standard toughness Three Point Bending tests (SENB) are too conservative since they are more constrained than actual pipeline. In this case, the adoption of a reduced notch depth, which is considered to reproduce well actual stress-strain conditions at the crack tip of a weld flaw, increases critical toughness values when compared to standard specimen configuration. Alternative solutions may be applied, even if not yet included in toughness standards. In particular, the Single Edge Notch Tensile (SENT) test is a possible solution reducing conservatism. A matter of concern for toughness characterization of weld joint is also represented by the notch orientation, since the weld microstructure is inhomogeneous in nature. The L–R oriented specimen (notch at the pipe inner surface) typically shows CTOD values strongly lower than the ones of L–T oriented specimens (through thickness notch) for both weld metal and heat affected zone. All these issues are discussed within this paper, while an advanced approach is presented to determine the resistance curve by using a single SENT specimen with the compliance method for crack growth evaluation. A relationship between the specimen elastic compliance and actual crack growth was determined through Finite Element Analysis and a Fracture Mechanics model. Such a relationship is presented and compared to other solutions available in scientific literature.
Developing Inspection Methodologies for Offshore Wind Turbine Facilities
Authors: Sheppard Robert E. , Puskar Frank J.
Published: February 2010

With the expected introduction of wind turbine facilities for the generation of electricity to the US Offshore Continental Shelf (OCS) waters, there is a need to evaluate how the long term operations of these facilities can be ensured through Integrity Management (IM) activities, particularly inspections. There is a long operational history of IM in the Gulf of Mexico, offshore California and Alaska, and around the world for fixed and floating oil and gas platforms for drilling and production. Both prescriptive and Risk-Based Inspection (RBI) methodologies have been established and implemented to direct inspection operations for these facilities. This experience provides a foundation for implementing similar Integrity Management programs for offshore wind turbine structures. Through the incorporation of existing guidance for subsea structures, above-water structures and access systems along with guidance from subject matter experts regarding critical inspection areas, inspection techniques, and inspection intervals, a guidance document has been developed which includes regional variations that address unique operating conditions in US waters. This work was funded by the US Department of the Interior, Minerals Management Service (MMS).
Where We Are Now: The U.S. Federal Regulatory Framework for Alternative Energy on the OCS
Authors: Trager Erin C.
Published: February 2010

Section 388 of the Energy Policy Act of 2005 (EPAct) amended the Outer Continental Shelf Lands Act (OCSLA) to grant the U.S. Department of the Interior (USDOI) discretionary authority to issue leases, easements, or rights-of-way for activities on the Outer Continental Shelf (OCS) that produce or support production, transportation, or transmission of energy from sources other than oil and gas, except for where activities are already otherwise authorized in other applicable law (e.g., the Deepwater Port Act of 1974 (33 U.S.C. 1501 et seq.), the Ocean Thermal Energy Conversion Act of 1980 (42 U.S.C. 9101 et seq.)) [1]. This authority was delegated to the Minerals Management Service (MMS), which was charged with developing regulations intended to encourage orderly, safe, and environmentally responsible development of alternative energy resources and alternate use of facilities on the OCS. MMS published its Alternative Energy/Alternate Use proposed rule in the Federal Register in July 2008 for public comment and held a series of public workshops to discuss the proposed regulations. The final regulations were submitted to the U.S. Office of Management and Budget (USOMB) on November 3, 2008 for clearance. In advance of final regulations, MMS announced an interim policy in November 2007 to authorize offshore data collection and technology testing activities in Federal waters. This measure was designed to allow developers to jumpstart data collection activities in support of potential future alternative energy development once regulations are in place. MMS has worked very closely with its State and Federal counterparts in implementing the interim policy, which has progressed most expeditiously on the Atlantic Coast. The interim policy is in effect until the MMS promulgates final rules. Beyond the MMS leasing process, several other Federal entities are involved in the permitting and licensing of alternative energy in the offshore environment, including the U.S. Army Corps of Engineers (USACE), the U.S. Coast Guard (USCG), and the Federal Aviation Administration (USFAA), among others. This paper will discuss the history of MMS’ program and policy development for offshore alternative energy activities; the steps taken to arrive at final regulations; as well as note the other regulatory bodies involved in the authorization of these activities in U.S. Federal waters.
Thermal Expansion Analysis of Pipe-in-Pipe System Having Multiple Bulkheads
Authors: Chen Q. , Wang L. Q. , Chia H. K. , Ngiam Andrew
Published: February 2010

This paper presents an analytical mathematical model for the thermal expansion analysis of pipe-in-pipe systems with multiple bulkheads. This analytical method is extended to study the effects on thermal expansion of multiple bulkheads for given internal installation temperature, operating temperature, tie-in spool piece arrangement, pipe submerged weight, seabed friction, pipe cross sectional area, pressure and axial stiffness of the pipes. The advantage of this method is that it yields purely analytical solution and that the analysis results provide the interaction forces in any cross section of the pipe-in-pipe system as well as the stresses and strains in both the inner and outer pipes, which provide enough information to optimize the pipe-in-pipe system design, especially at the bulkhead location. The examples illustrated in the paper show that with the application of multiple bulkheads in the pipe-in-pipe system, the interaction forces between bulkheads and pipes can be reduced, which allow less onerous bulkhead design.
Potential of Conventional and Unconventional Hydrocarbons: Comparison of Resources, Reserves, Recovery Factors, and Technologies
Authors: Lakatos Istva´n , Lakatos-Szabo´ Julianna
Published: February 2010

The paper deals with the availability of natural hydrocarbons until 2100. Starting point of the evaluation is that the global demand will not be met by production of conventional oil and gas. Basis of the discussion is the comparison of available resources and reserves, recovery factors and technologies. The analysis comprised oil shale, tar sand, gas shale, tight sand gas, coalbed methane and gas hydrates. Taking the data of competent organizations into account, obviously the global resources of unconventional oil and gas significantly exceed the availability of conventional natural hydrocarbons in spite of the fact that their recovery efficiency is extremely low. Although the production cost (operation expenditure) of unconventional hydrocarbons is usually much higher than those of the conventional ones, industrial scale production of tar sand oil, tight sand gas and coalbed methane has started over two decades ago and their contribution to total oil and gas production is already substantial in several countries (US, Canada). The authors stated, however, that wider application of sophisticated technology to recover unconventional hydrocarbons needs more extensive and intensive R&D activity and further, new paradigms are necessary in education, research, production, field management, and governmental regulation.
Numerical Simulation of Ice Action to a Lighthouse
Authors: Gu¨rtner Arne , Bjerka˚s Morten , Ku¨hnlein Walter , Jochmann Peter , Konuk Ibrahim
Published: February 2010

Ice actions to the Norstro¨msgrund lighthouse are simulated by means of the computational cohesive element model. The numerical model is developed in the framework of finite elements. Fracture of the ice sheet is accounted for by the cohesive elements placed at internal finite element mesh boundaries in order to track traction versus separation. One single ice event on the Norstro¨msgrund lighthouse is selected for which the ice loads as well as outer boundary conditions are recorded. This event serves as a basis for comparison to the computational method presented in this paper. The simulation results indicate that the proposed numerical method captures many of the qualitative observation as well as quantitatively derives comparable global ice loads to the lighthouse to those of the selected ice event. Future analysis should include additional validation to variations in ice thickness and drift speed.
The Influence of the UOE Forming Process on Material Properties and Collapse of Deepwater Linepipe
Authors: Timms Chris , Mantovano Luciano , Ernst Hugo A. , Toscano Rita , DeGeer Duane , Swanek Doug , de Souza Marcos , Chad Luis C.
Published: February 2010

It has been demonstrated in previous work that, for deepwater applications, the cold forming process involved in UOE pipe manufacturing significantly reduces pipe collapse strength. To improve the understanding of these effects, Tenaris has embarked on a program to model the stages of the UOE manufacturing process using finite element methods. Previous phases of this work formulated the basis for model development and described the 2D approach taken to model the various stages of manufacture. More recent developments included some modeling enhancements, sensitivity analyses, and comparison of predictions to the results of full-scale collapse testing performed at C-FER. This work has shown correlations between manufacturing parameters and collapse pressure predictions. The results of the latest phase of the research program are presented in this paper. This work consists of full-scale collapse testing and extensive coupon testing on samples collected from various stages of the UOE pipe manufacturing process including plate, UO, UOE, and thermally-aged UOE. Four UOE pipe samples manufactured with varying forming parameters were provided by Tenaris for this test program along with associated plate and UO samples. Full-scale collapse and buckle propagation tests were conducted on a sample from each of the four UOE pipes including one that was thermally aged. Additional coupon-scale work included measurement of the through-thickness variation of material properties and a thermal ageing study aimed at better understanding UOE pipe strength recovery. The results of these tests will provide the basis for further refinement of the finite element model as the program proceeds into the next phase.
Effect of Different Cooling Rate on HAZ Microstructure of 2205 Duplex Stainless Steels
Authors: Xiong Qingren , Feng Yaorong , Zhao Wenzhen , Huo Chunyong , Liu Chuan , Ji Lingkang , Qin Changyi
Published: February 2010

The effects of cooling rate ω8/5 and ω12/8 on the simulated HAZ microstructure transformation in 2205 duplex stainless steel are studied in this paper. The results indicate that 1200°C ∼ 800°C is the temperature range in which the microstructure transits the most violently for 2205 steel, and is also the cooling interval, that affects the phase proportion and microstructure morphology the most distinctly. Accordingly, It is more efficient to use ω12/8 as the parameter to investigate the microstructure transformation of welding HAZ microstructure of this material. The cooling rate in this interval will affect the microstructure transformation of HAZ microstructure of 2205 steel remarkably.
Utilization of Gas-Liquid Cylindrical Cyclone (GLCC©) Compact Separator for Solids Removal—Part I: Minimum Required Liquid Injection Rate
Authors: Arismendi R. , Gomez L. , Wang S. , Mohan R. , Shoham O. , Oglesby K.
Published: February 2010

The hydrodynamic behavior of gas-liquid-solids in a modified GLCC© has been studied for the first time experimentally and theoretically. A GLCC© experimental facility has been designed, constructed and utilized to acquire data on gas-solid-liquid flow in both upstream 2-inch injection line horizontal section and in the 3-inch GLCC©. Experimental data have been acquired for the minimum gas velocity required to transport the solids up to the liquid injection point, and for the minimum liquid injection rate necessary to wet the solids and capture them in the liquid phase. The data have been acquired for 4 solid particle sizes of 5 μm, 25 μm, 50 μm and 150 μm. A mechanistic model has been developed or modified for solids transport/ separation, for the prediction of the minimum transport gas velocity, and the required minimum liquid injection rate. A comparison between the model prediction and the acquired experimental data shows good agreement. The average relative error for minimum transport gas and liquid velocities are, 4.3% and 9.55%, respectively.
A Modular Differential Dielectric Sensor (DDS) for Use in Multiphase Separation, Process Measurement and Control—Part I: Analytical Modeling
Authors: Xiang D. , Mohan R. , Marrelli J. , Wang S. , Shoham O.
Published: February 2010

Oil industry increasingly demands accurate and stable continuous measurement of the percent water in crude oil production streams (watercut) over the entire 0 to 100% range. High accuracy and stability are also required for surface measurement to support niche applications such as control of processes which remove trace amounts of oil and particulates from produced water prior to disposal. Differential Dielectric Sensors (DDS) have been developed by Chevron as independent tools connected with multiphase meters for process management and composition measurement. This paper is a two-part paper — the first part (current paper) deals with analytical modeling of the DDS (configured in a single ended mode) and the second part discusses the results of key experimental investigations obtained in a differential mode. The main objective of this paper is to develop appropriate mathematical models for the DDS which characterize the microwave attenuation and phase shift as a function of fluid properties, sensor geometry and operational conditions. Forward models based on the analysis of microwave propagation have been developed for sensors configured as circular waveguides. Results of this project will be useful for optimization and refinement of multiphase meters.
Design of a Mooring System With Synthetic Ropes for the FLOW Wave Energy Converter
Authors: Fonseca Nuno , Pascoal Ricardo , Morais Tiago , Dias Renato
Published: February 2010

Martifer Energia is developing a concept of a wave energy converter (WEC) to be used at near shore locations with water depths starting at around 40m. It is a floating device composed of two bodies connected by a one degree of freedom articulation. The energy is extracted at the articulation by a power takeoff system actuated by the relative motion between the bodies. One of the important components of many WECs is the mooring system, since usually the cost is large compared global cost of the device. In this case the WEC will be moored by a spread mooring that allows the device to weathervane with the environmental loads. The paper presents one design solution for the mooring system investigated during the development stage of the concept. It is composed of four hybrid lines, each one with a segment of nylon rope connected to the floating device and a part of chain that contacts with the sea bottom and ends at the anchor. The wave frequency hydrodynamics are first calculated with a frequency domain boundary element method. The nonlinear cable dynamics problem, which is coupled to the slow drift motions of the floater, is solved in the time domain by a finite difference method. The design considers the climatology of the future area of operation of the prototype. Since the loads on the lines depend on the characteristics of the lines themselves, the design solution is obtained iteratively. Appropriate safety factors are considered. The result is the number of mooring lines, their angular separation, length and diameter of each line component.
Simulation of Water Wave Transformation Using Higher Order Mild-Slope Equation
Authors: Hsu Tai-Wen , Lin Ta-Yuan , Hsiao Kuan-Yu , Chen Shiao-Yin
Published: February 2010

A higher-order mild-slope equation (HOMSE) was developed using classical Galerkin method in which the depth function is expanded to the third-order. Wave nonlinearity and bottom slope parameters are involved in the depth function solved on the bases of the multiple-scale perturbation method. The equation is solved subject to the radiation boundary conditions by means of the procedure of parabolic formulation. Good agreement between numerical results and experimental data has been observed for wave propagation over a submerged obstacle and a sloping beach.
An Application of Integrated Coastal Models on Protection of Sediment Deposition at Taichung Harbor
Authors: Hsu Tai-Wen , Jhu Yu-Jie
Published: February 2010

The main objective of this paper is to study the protection of sediment siltation and shoreline evolution in Taichung harbor using two numerical models of SMC (Coastal Modeling System) and GENESIS (GENEralized model for SImulating Shoreline change System). Numerical results of wave height in the vicinity of groins were compared to validate the capability of SMC model. In addition, the transport parameters, K1 and K2 in GENESIS are calibrated. Some numerical cases were runned to simulate the nearshore hydrodynamics, the sediment transportation and siltation on the north area with siltation of Taichung harbor. In particular, a beach nourishment measure is proposed based on GENESIS simulations of shoreline change on southern eroded coast.
Centrifuge Tests on Dynamically Installed Anchors
Authors: O’Loughlin Conleth D. , Richardson Mark D. , Randolph Mark F.
Published: February 2010

Dynamically installed anchors are torpedo shaped and are designed so that after release from a designated height above the seafloor will penetrate to a target depth in the seabed by the kinetic energy obtained through free-fall and through the self-weight of the anchor. This paper presents results from an extensive series of centrifuge tests undertaken to both inform expected anchor penetrations in normally consolidated clay and form the basis for calibrating an analytical anchor embedment model. The database indicates that for anchors with no flukes, expected anchor tip embedment depths are 2 to 3 times the anchor length for impact velocities approaching 30 m/s, with a dependence on both impact velocity and to a greater extent anchor mass. The centrifuge data were used to calibrate an analytical embedment model, based on strain rate dependent shearing resistance and fluid mechanics drag resistance. Back-figured strain rate parameters increase with increasing impact velocity and are in the range 0.2–0.5 (logarithmic function) and 0.06–0.12 (power function). As the strain rates in the centrifuge tests are approximately 200 times equivalent strain rates in the field, the lower bound strain rate parameters are considered more appropriate for field conditions.
Comparative Study of Wave Load Effects for Two Wave Energy Converter Concepts
Authors: Taghipour Reza , Arswendy Arswendy , Moan Torgeir
Published: February 2010

This paper deals with a comparative study of hydrodynamic and structural performance for two different concepts of the FO3 wave energy converter (WEC). The WEC consists of 22 bodies: a semisubmersible platform as supporting structure and 21 buoys as point absorbers. The buoys can slide along some guides that are attached to the deck of the platform. The power is produced from the relative motion between the buoys and the supporting structure by means of hydraulic machinery on the deck. In the first FO3 concept, known as the Alternative 1 FO3, the supporting structure is a ring pontoon semisubmersible platform. The other concept is known as the Alternative 2 FO3, in which the Alternative 1’s semisubmersible platform is replaced by a cylindrical-pontoon platform. As one of the scenarios which is considered in this paper, the buoys are locked at their design draft. The objective is to compare the motions and the axial force and bending moment transfer functions in the column- and guide-deck connections for these two concepts.
Environmental Effects on Fatigue Strength of Armour Wire for Flexible Risers
Authors: Berge Stig , Langhelle Nina K. , Eggen Tor Gunnar
Published: February 2010

Fatigue of armour wires is in many cases a limiting factor for the design life of flexible risers. Until a few years ago, fatigue design was based on SN data obtained by component testing in air, with the implicit assumption that the environment in a pipe annulus is benign with regard to fatigue of armour wires. Service experience has shown that a pipe annulus may contain species that are aggressive with respect to steel, and could affect fatigue strength significantly. In a consistent design methodology these effects should be taken into account. MARINTEK in co-operation with SINTEF Materials and Chemistry is running a Joint Industry Project (JIP) with the aim of developing a basis for fatigue design of armour wire in which the effects due to the chemical environment in a pipe annulus are accounted for. The project started in 2001 and is now into a Phase III to be completed in 2008. A Phase IV is proposed, to be carried out in 2009–2011. Testing is carried out on tensile armour wire in air, and in aqueous environments and with H2S and/or CO2 at various partial pressures. SN curves have been obtained for more than 50 different combinations of material grade, environmental composition and loading parameters. In this paper the methodology of the testing is presented, with some general results. The following aspects of corrosion fatigue are discussed: - Procedures for fatigue testing of armour wire in corrosive environments, test protocol. - The scope for establishing common fatigue design criteria for armour wire, based on strength classes. - The effect of loading frequency in corrosion fatigue, assessment of fatigue strength criteria for long lives. - The fatigue limit in corrosion fatigue.
DNA-PKcs Controls an Endosomal Signaling Pathway for a Proinflammatory Response by Natural Killer Cells
Authors: Rajagopalan Sumati , Moyle Mark W. , Joosten Irma , Long Eric O.
Published: February 2010

DNA-dependent protein kinase and Akt are required for the activation of NF-κB by an endosomal receptor.
A Radical Approach to Resistance
Authors: Adler Elizabeth M.
Published: February 2010

Sublethal treatment with antibiotics can foster the development of antibiotic-resistant strains through a ROS-dependent increase in the rate of mutagenesis.
Gaining Entry
Authors: Gough Nancy R.
Published: February 2010

Inflammatory hypoxia stimulates the translocation of bacteria across intestinal epithelia.
Assay of Colistin and Colistin Methanesulfonate in Plasma and Urine by Liquid Chromatography-Tandem Mass Spectrometry
Authors: Gobin Patrice , Lemaître Florian , Marchand Sandrine , Couet William , Olivier Jean-Christophe
Published: February 2010

A rapid high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed for the routine quantification of colistins A and B and their prodrugs, colistin methanesulfonate (CMS) A and CMS B, respectively, in human plasma and urine by using polymyxin B1 as the internal standard (IS). CMS concentrations were determined indirectly by subtracting the colistin concentrations determined in biological samples from the whole colistin concentrations determined after sample treatment with sulfuric acid in order to hydrolyze CMS into colistin. After extraction on a solid-phase extraction column, the colistins were separated on an XBrigde C
18
column with isocratic elution (run time, 3.8 min). The mobile phase was 0.1% (vol/vol) formic acid in acetonitrile-0.1% (vol/vol) formic acid in water (20:80, vol/vol), run at a 0.2-ml/min flow rate. Ions were detected in the turbo-ion-spray-positive and multiple-reaction-monitoring modes. The ions monitored (precursor [M + 2H]
2+
to product ions) were
m/z
585.5/101.2 for colistin A,
m/z
578.5/101.2 for colistin B, and
m/z
602.5/241.2 for IS. Prevalidation studies demonstrated the stability of CMS in biological samples and extracts, a key point for the reliable quantification of colistin and CMS. The assay was accurate and reproducible for the quantification of colistins A and B and CMSs A and B in plasma samples over concentration ranges appropriate for pharmacokinetic studies: 0.024 to 6.144, 0.015 to 3.856, 0.029 to 7.492, and 0.010 to 2.508 μg/ml, respectively. In urine samples, the assay was validated over the same concentration ranges for colistins and over concentration ranges of 0.058 to 7.492 μg/ml and 0.020 to 2.508 μg/ml for CMSs A and B, respectively.
Anti-Porphyromonas gingivalisand Anti-Inflammatory Activities of A-Type Cranberry Proanthocyanidins
Authors: La Vu Dang , Howell Amy B. , Grenier Daniel
Published: February 2010

A-type cranberry proanthocyanidins (AC-PACs) have recently been reported to be beneficial for human health, especially urinary tract health. The effect of these proanthocyanidins on periodontitis, a destructive disease of tooth-supporting tissues, needs to be investigated. The purpose of this study was to investigate the effects of AC-PACs on various virulence determinants ofPorphyromonas gingivalisas well as on the inflammatory response of oral epithelial cells stimulated by this periodontopathogen. We examined the effects of AC-PACs onP. gingivalisgrowth and biofilm formation, adherence to human oral epithelial cells and protein-coated surfaces, collagenase activity, and invasiveness. We also tested the ability of AC-PACs to modulate theP. gingivalis-induced inflammatory response by human oral epithelial cells. Our results showed that while AC-PACs neutralized all the virulence properties ofP. gingivalisin a dose-dependent fashion, they did not interfere with growth. They also inhibited the secretion of interleukin-8 (IL-8) and chemokine (C-C motif) ligand 5 (CCL5) but did not affect the secretion of IL-6 by epithelial cells stimulated withP. gingivalis. This anti-inflammatory effect was associated with reduced activation of the nuclear factor-κB (NF-κB) p65 pathway. AC-PACs may be potentially valuable bioactive molecules for the development of new strategies to treat and preventP. gingivalis-associated periodontal diseases.
In Vitro
Resistance Profile of the Hepatitis C Virus NS3/4A Protease Inhibitor TMC435
Authors: Lenz Oliver , Verbinnen Thierry , Lin Tse-I , Vijgen Leen , Cummings Maxwell D. , Lindberg Jimmy , Berke Jan Martin , Dehertogh Pascale , Fransen Els , Scholliers Annick , Vermeiren Katrien , Ivens Tania , Raboisson Pierre , Edlund Michael , Storm Susan , Vrang Lotta , de Kock Herman , Fanning Gregory C. , Simmen Kenneth A.
Published: February 2010

TMC435 is a small-molecule inhibitor of the NS3/4A serine protease of hepatitis C virus (HCV) currently in phase 2 development. The
in vitro
resistance profile of TMC435 was characterized by selection experiments with HCV genotype 1 replicon cells and the genotype 2a JFH-1 system. In 80% (86/109) of the sequences from genotype 1 replicon cells analyzed, a mutation at NS3 residue D168 was observed, with changes to V or A being the most frequent. Mutations at NS3 positions 43, 80, 155, and 156, alone or in combination, were also identified. A transient replicon assay confirmed the relevance of these positions for TMC435 inhibitory activity. The change in the 50% effective concentrations (EC
50
s) observed for replicons with mutations at position 168 ranged from <10-fold for those with the D168G or D168N mutation to ∼2,000-fold for those with the D168V or D168I mutation, compared to the EC
50
for the wild type. Of the positions identified, mutations at residue Q80 had the least impact on the activity of TMC435 (<10-fold change in EC
50
s), while greater effects were observed for some replicons with mutations at positions 43, 155, and 156. TMC435 remained active against replicons with the specific mutations observed after
in vitro
or
in vivo
exposure to telaprevir or boceprevir, including most replicons with changes at positions 36, 54, and 170 (<3-fold change in EC
50
s). Replicons carrying mutations affecting the activity of TMC435 remained fully susceptible to alpha interferon and NS5A and NS5B inhibitors. Finally, combinations of TMC435 with alpha interferon and NS5B polymerase inhibitors prevented the formation of drug-resistant replicon colonies.
Rapid Change of Methicillin-Resistant
Staphylococcus aureus
Clones in a Chinese Tertiary Care Hospital over a 15-Year Period
Authors: Chen Hongbin , Liu Yudong , Jiang Xiuhong , Chen Minjun , Wang Hui
Published: February 2010

The incidence of methicillin-resistant
Staphylococcus aureus
(MRSA) has been increasing yearly at Peking Union Medical College Hospital (PUMCH). In order to understand the molecular evolution of MRSA at PUMCH, a total of 466 nonduplicate
S. aureus
isolates, including 302 MRSA and 164 methicillin-susceptible (MSSA) isolates recovered from 1994 to 2008 were characterized by staphylococcal cassette chromosome
mec
(SCC
mec
) typing,
spa
typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). The 302 MRSA isolates were classified into 12
spa
types and 9 sequence types (STs). During the years from 1994 to 2000, the most predominant MRSA clone was ST239-MRSA-III-
spa
t037. Since 2000, ST239-MRSA-III-
spa
t030 has rapidly replaced t037 and become the major clone. Another clone, ST5-MRSA-II-
spa
t002 emerged in 2002 and constantly existed at a low prevalence rate. The 164 MSSA isolates were classified into 62
spa
types and 40 STs. ST398 was the most common MLST type for MSSA, followed by ST59, ST7, ST15, and ST1. Several MSSA genotypes, including ST398, ST1, ST121, and ST59, were identical to well-known epidemic community-acquired MRSA (CA-MRSA) isolates. MLST eBURST analysis revealed that the ST5, ST59, and ST965 clones coexisted in both MRSA and MSSA, which suggested that these MRSA clones might have evolved from MSSA by the acquisition of SCC
mec
. Two
pvl
-positive ST59-MRSA-IV isolates were identified as CA-MRSA according to the clinical data. Overall, our data showed that the ST239-MRSA-III-
spa
t037 clone was replaced by the emerging ST239-MRSA-III-
spa
t030 clone, indicating a rapid change of MRSA at a tertiary care hospital in China over a 15-year period.
Heat Stress Cognate 70 Host Protein as a Potential Drug Target against Drug Resistance in Hepatitis B Virus
Authors: Wang Yu-Ping , Liu Fei , He Hong-Wei , Han Yan-Xin , Peng Zong-Gen , Li Bao-Wei , You Xue-Fu , Song Dan-Qing , Li Zhuo-Rong , Yu Li-Yan , Cen Shan , Hong Bin , Sun Chen-Heng , Zhao Li-Xun , Kreiswirth Barry , Perlin David , Shao Rong-Guang , Jiang Jian-Dong
Published: February 2010

Heat stress cognate 70 (Hsc70) is a host protein associated with hepatitis B virus (HBV) replication. The goal of this study was to investigate whether Hsc70 could be an anti-HBV drug target. Our results showed that introducing Hsc70 increased HBV replication in HBV
+
human hepatocytes (HepG2.2.15 cells). The coiled-coil region on Hsc70 (nucleotides 1533 to 1608; amino acids 511 to 536) was the key sequence for HBV replication. Knockdown of Hsc70 expression by RNA interference (RNAi) largely inhibited HBV replication with no cytotoxicity to the host. Using an Hsc70 mRNA screening assay, the natural compound oxymatrine (OMTR) was found to be a selective inhibitor for Hsc70 expression. Then, OMTR was used to investigate the potential of Hsc70 as an anti-HBV drug target. OMTR inhibited Hsc70 mRNA expression by 80% and HBV DNA replication by over 60% without causing cytotoxicity. The anti-HBV effect of OMTR appeared to be mediated by destabilizing Hsc70 mRNA. The half-life (
T
1/2
) of Hsc70 mRNA decreased by 50% in OMTR-treated hepatocytes. The Hsc70 mRNA 3′-untranslated-region (UTR) sequence was the element responsible for OMTR's destabilization activity. OMTR suppressed HBV
de novo
synthesis at the reverse transcription stage from pregenomic RNA (pgRNA) to DNA and was active against either wild-type HBV or strains resistant to lamivudine, adefovir, and entecavir. Therefore, host Hsc70 could be a novel drug target against HBV, and OMTR appears to inhibit HBV replication by destabilizing Hsc70 mRNA. As the target is not a viral protein, OMTR is active for either wild-type HBV or strains resistant to reverse transcriptase (RT) inhibitors.
Substitution of the
Bordetella pertussis
Lipid A Phosphate Groups with Glucosamine Is Required for Robust NF-κB Activation and Release of Proinflammatory Cytokines in Cells Expressing Human but Not Murine Toll-Like Receptor 4-MD-2-CD14
Authors: Marr Nico , Hajjar Adeline M. , Shah Nita R. , Novikov Alexey , Yam Cathy S. , Caroff Martine , Fernandez Rachel C.
Published: February 2010

Bordetella pertussis
endotoxin is a key modulator of the host immune response, mainly due to the role of its lipid A moiety in Toll-like receptor 4 (TLR4)-mediated signaling. We have previously demonstrated that the lipid A phosphate groups of
B. pertussis
BP338 can be substituted with glucosamine in a BvgAS-regulated manner. Here we examined the effect of this lipid A modification on the biological activity of
B. pertussis
endotoxin. We compared purified endotoxin and heat-killed
B. pertussis
BP338 whole cells that have modified lipid A phosphate groups to an isogenic mutant lacking this modification with respect to their capacities to induce the release of inflammatory cytokines by human and murine macrophages and to participate in the TLR4-mediated activation of NF-κB in transfected HEK-293 cells. We found inactivated
B. pertussis
cells to be stronger inducers of proinflammatory cytokines in THP-1-derived macrophages when lipid A was modified. Most notably, lack of lipid A modification abolished the ability of purified
B. pertussis
endotoxin to induce the release of inflammatory cytokines by human THP-1-derived macrophages but led to only slightly reduced inflammatory cytokine levels when stimulating murine (RAW 264.7) macrophages. Accordingly, upon stimulation of HEK-293 cells with inactivated bacteria and purified endotoxin, lack of lipid A modification led to impaired NF-κB activation only when human, and not when murine, TLR4-MD-2-CD14 was expressed. We speculate that in
B. pertussis
, lipid A modification has evolved to benefit the bacteria during human infection by modulating immune defenses rather than to evade innate immune recognition.
Initial community response to a childhood drowning prevention programme in a rural setting in Bangladesh
Authors: Rahman A , Miah A H , Mashreky S R , Shafinaz S , Linnan M , Rahman F
Published: February 2010

Objectives

To describe the development, community acceptability, feasibility, and sustainability of a pilot drowning prevention intervention for rural children, 1–4 years old, in Bangladesh.

Methods

A prevention package was formulated and piloted in four rural communities of Bangladesh for 3 months. Focus group discussions and in-depth interviews were organised with stakeholders to elicit community acceptability, feasibility, and sustainability of the proposed interventions.

Results

Increased supervision of children, raising awareness on water safety, and educating the community on first response skills were the three core aspects identified through workshops to include in the intervention package. During development of interventions emphasis was given to finding low-cost local resources. To increase child supervision, creation of drowning-safe homes and establishment of community crèches were identified. To create heightened water safety, formation of village committees and conduction of courtyard and social autopsy meetings with communities were considered. The community actively participated and considered that these interventions would be useful for prevention of child drowning. There was also an increasing demand for some of these interventions.

Conclusion

Use of low-cost local resources, community participation, and increasing demand of the interventions indicated that the package was acceptable, feasible, and sustainable to the community. To determine the effectiveness of the package demands implementation on a larger sample.