bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation Into Fretting Behaviour in Pressure Armor Wires of Unbonded Flexible Pipes
Authors: Perera S. D. Rasika , Fernando Upul S. , Sheldrake Terry , Clements Richard
Published: May 2009

The possibility of fretting damage in pressure armor wires of flexible pipes has been investigated. A novel experimental facility which is capable of simulating nub/valley contact conditions with dynamic slip, representative of actual pipe loading, has been developed. The test setup is equipped with a state of the art data acquisition system and a controller with transducers to measure and control the normal load, slip amplitude and friction force at the contact in addition to the hoop stress in the wire. Tests were performed with selected loading and the fretted regions were examined using an optical microscope. Results show that the magnitude of contact loading and the slip amplitude have a distinct effect on surface damage. Surface cracks originated from fretting scar were observed at very high contact loads in mixed slip sliding while surface damage predominantly due to wear was observed under gross slip. The position of surface cracks and the wear profile have been related to the contact pressure distribution. The evolution of friction force and surface damage under different slip and normal pressure conditions are presented. The effect of a general grease lubricant on friction behavior is also discussed.
Subsea Pipeline Monitoring Using Fibre Optic Strain Sensors
Authors: Roberts Damon
Published: May 2009

Fibre optic strain sensors are being increasingly deployed subsea due to significant improvements in reliability and ease of deployment brought about by embedding the optical fibre within a composite carrier that simply clamps to the structure to be monitored. There is significant experience in deploying these sensors on a variety of risers by a number of different installation methods as part of project integrity management strategies. Building on experience from monitoring risers, the technology is now being applied to other subsea infrastructure including manifolds and flowlines for monitoring parameters including pressure, axial load, shape and temperature. The same technology has even been deployed downhole for measuring loads in production tubing. Two different types of instruments have been designed to meet the needs of the industry, namely single point sensors and sensors that measure the profile of parameters over an extended distance. Point sensors have been developed to measure axial load, internal pressure, curvature and temperature. Each sensor mechanically attaches to the pipeline to transfer strains and temperatures in the pipeline. The instrument has been demonstrated to detect pressure changes from quasi-static to hundreds of hertz as required for conditions such as flow induced vibration and detecting slug flow. By locating a number of pressure sensors along a flowline the onset of waxing or hydrate build-up can be detected. The flexibility of the technology enables deployment in the yard, on deck and even retrofit installation by ROV. Profile sensors have been developed to measure bending profiles of flowline buckle regions, flowline free spans and riser touchdown zones. The profile sensors are elongated instruments that cover the entire length of the flowline to be monitored. Fibre optic sensors are embedded within a composite carrier during a continuous manufacturing process such as filament winding or pultrusion. Instruments with as many as 280 embedded sensors have been manufactured and deployed to date. Instruments have been developed to measure upheaval and lateral buckling strain profiles in HPHT flowlines. Deployment methods have been developed for retrofit installation and for installation on deck. The paper will present the current status of subsea pipeline monitoring using fibre optic strain sensors including results of both point and profile sensors. In addition further applications for the technology will be discussed.
Setpoint Chasing for Thruster-Assisted Position Mooring
Authors: Nguyen Dong T. , So̸rensen Asgeir J.
Published: May 2009

This paper presents a new concept for control of thruster-assisted position moored vessel using setpoint chasing. The mooring system is designed to compensate the mean environmental loads up to a certain limit of the environmental conditions. In the present industrial position mooring (PM) system, the thrusters are used to damp the vessel’s dynamical motions and to provide compensation of any line break. The main contribution in this paper is to extend the damping control used in industrial PM system with improved restoring and mean force control. In order to avoid conflicting control action with the mooring system, the equilibrium position of the uncontrolled vessel will be found using setpoint chasing. The setpoint chasing with proportional control will be developed to prevent a possible resonance situation by shifting the natural frequency of the moored vessel out of the bandwidth of the excitation loads. The setpoint chasing with integral control will improve the ability to prevent line break in extreme conditions by compensating the mean drift loads together with the mooring system. Simulation and experiment will be carried out to verify the advantages of the setpoint chasing strategies.
Implementation of a Bottom-Hole Assembly Program
Authors: Bhalla Kenneth , Gong Lixin , McKown George
Published: May 2009

A state of the art windows graphical user interface (GUI) program has been developed to predict and design the bottom-hole assembly (BHA) performance for drilling. The techniques and algorithms developed in the program are based upon those developed by Lubinski and Williamson. The BHA program facilitates in conducting parametric studies, and in making field decisions for optimal performance. The input parameters may include: formation class, dip angle, hole size, drill collar size, number of stabilizers, stabilizer spacing. The program takes into consideration bit-formation characteristics and interaction, drill collar sizes, square collars, shock absorbers, MWD tools, reamer tools, directional tools, rotary steerable systems etc. The output may consist of hole curvature (build up or drop rate), hole angle, weight on bit and is presented in drilling semantics. Additionally, the program can perform mechanical analyses and solve for the bending moments and reactions forces. Moreover, the program has the capability to predict the wellpath using a drill ahead algorithm. The program consists of a mathematical model which makes assumptions of 2-D, static, constant hole curvature resulting in a robust computationally efficient tool that produces rapid reliable results in the field.
Hydrodynamic Coefficients for In-Line Vortex Induced Vibrations
Authors: Aronsen Kristoffer H. , Larsen Carl Martin
Published: May 2009

The paper presents results from an experimental investigation of hydrodynamic forces on a cylinder under forced in-line motions. Measured forces are decomposed into added mass, driving force and average drag components. From a large set of experiments it has been possible to draw a complete map for in-line force coefficients as function of arbitrary combinations of motion amplitude and frequency. The paper presents test set-up, data processing and how the coefficients can be used in an empirical force coefficient model for calculation of in-line vibrations of slender marine structures with arbitrary damping. Such analyses are in particular important for free spanning pipelines, where damping from pipe/seafloor interaction will reduce the response amplitudes and hence also stresses and fatigue damage.
Slow-Drift Pitch Motions and Air-Gap Observed From Model Testing With Moored Semisubmersibles
Authors: Stansberg Carl Trygve
Published: May 2009

Low-frequency pitch motions of a moored semisubmersible in irregular sea states are analyzed. Physical mechanisms and significance to air-gap problems are addressed. Excitation from wave drift and from moorings/risers is primarily considered, Effects from current and wind are also addressed. Related challenges in deepwater model testing of semis with truncated moorings are discussed. Motion and air-gap data from two previously performed model tests are analysed. Catenary moorings in 335m water depth and in 1100m water depth, respectively, are considered. Model scales are 1:55 and 1:150, respectively. Observed slow-drift pitch components are of the same magnitude level as the wave-frequency components. Comparisons to coupled numerical analysis models are made. Wave drift moment coefficients calibrated empirically according to experiments were used, since the original coefficients gave too low results. The final comparisons show good agreement for the 1:55 case. For the 1:150 case, fairly good agreement is found, but some deviations are observed and believed to be due to poorer wave repeatablity. Tests with truncated moorings at half of the two actual depths were also included, for a check of methods for deepwater model tests performed at reduced depths and combine with numerical analysis (hybrid verification). The importance of proper experimental reproduction at reduced depths, of full-depth pitch and air-gap, is addressed. The results show that with the actual truncation designs, reasonable agreements are obtained, but use of the scale 1:150 seems to give too large uncertainties due to the poorer wave repeatability.
Development and Production of Ultra-High Strength Linepipes With Dual-Phase Microstructure for High Strain Application
Authors: Ishikawa Nobuyuki , Okatsu Mitsuru , Shimamura Junji , Endo Shigeru , Shikanai Nobuo , Kondo Joe , Muraoka Ryuji
Published: May 2009

Extensive studies to develop high strength linepipes with higher deformability have been conducted. One of the key technologies for improving deformability is dual-phase microstructural control. Steel plate with ferrite-bainite microstructure can be obtained by applying Thermo-mechanical controlled processing, TMCP, made up with controlled rolling and accelerated cooling process. Low carbon-boron free steels were used to enable the ferrite formation during cooling after controlled rolling, and the accelerated cooling process with ultimate cooling rate enabled to achieve high strength of up to X120 grade. On-line heating process by induction device was also applied subsequently after accelerated cooling in order to improve Charpy energy of the base material and homogeneity of material properties in the plate. Trial production of X120 high deformability linepipe was also conducted by applying dual-phase microstructural control. Microstructural and mechanical properties of X120 linepipe are introduced in this paper.
Towards the Comprehensive Modeling of Multiphase Fluid Flow Pumping Systems Using Smoothed Particle Hydrodynamics (SPH)
Authors: Zaman M. S. , Mousavizadegan S. Hossein , Satish M. G. , Islam M. Rafiqul
Published: May 2009

Multiphase pumping is a viable option in hydrocarbon production at different conditions and especially in more challenging environments. A multiphase pump system can boost pressure without the need to separate the phases and occupies less space and weight, which is valuable for offshore applications. Sub-sea multiphase pumping in deepwater will be reliable, bringing a new economic dimension to the development of satellite oil fields. It is necessary to study the different scenarios that may happen during the transferring of a multiphase fluid through the piping systems. The flow patterns transition in horizontal pipes has been studied theoretically using the smoothed particle hydrodynamics (SPH). SPH is a Lagrangian approach, with the particles themselves being the framework on which the fluid equations are solved, and so there is no grid to constrain the dynamic range or geometry of the system being modeled. In the Lagrangian formulation, the mesh follows the fluid motion and this automatically guarantees the accurate treatment of interfaces that is really a disadvantage of the Eulerian approach. Therefore, for multi-material (oil, water, gas and also sand) problems, Lagrangian method is the most accurate tool for tracking the material interfaces. In addition, geometrically complex and/or dynamic boundaries can be handled without undue difficulty. The simultaneous flow of air and water as two representing fluids are studied through a horizontal pipe using SPH method. The mathematical model is represented and the position of the fluids particles is obtained at different time steps. The objective is to simulate the flow patterns that will help us to design multiphase fluid pumping systems and to identify the variables of interest for instrumentation.
California Wave Energy Resource Evaluation
Authors: Wilson James H. , Beyene Asfaw
Published: May 2009

In this paper, a collection of deep water (>100 m) wave records was assessed to create a long-term, statistically reliable data set. These wave data were derived from the Coastal Information Data Program (CDIP) Buoy Data from UCSD Scripps Institute of Oceanography, National Data Buoy Center (NDBC) Buoy Data from NOAA, and other sources. From this data set, long-term annual averages and monthly wave probability distributions were analyzed for ten one degree latitude bins bounded by the 100 m and 1000 m depth contours seaward of the California coast. The probability distributions were used to quantify the potential for useful electricity extraction from the coastal wave of California. Optimal locations for developing wave energy installations are specified. The California coast north of Point Conception has an ideal wave resource for the generation of electricity from wave energy. South of Point Conception the wave energy arriving from North Pacific storms is efficiently blocked by the significant change in California coast orientation south of Point Conception and the Channel Islands. The near coastal Southern California (SOCAL) region has a significantly reduced wave resource compared to the California coast north of Pont Conception. Factors impacting the status of ocean wave energy technologies and their development are also discussed. Applicability of the wave statistical results is critical to determine the average “wave to wire” efficiency for the many different types of wave energy converter (WEC) technologies that exist in many different states of commercial development.
An Assessment of Structural Design Guidelines for Offshore Wind Turbines
Authors: Saigal Rakesh K. , Dolan Dan , Der Kiureghian Armen , Camp Tim , Smith Charles E.
Published: May 2009

This paper addresses the need for U.S. standards to establish design requirements for offshore wind turbine support structures. There are wind power resources in U.S. waters that can be developed to generate substantial amounts of clean, renewable energy. While a number of offshore wind farms have been proposed for U.S. waters none have been built. The U.S. Minerals Management Service and the National Renewable Energy Laboratory have recently commissioned a study to compare and benchmark the International Electrotechnical Commission (IEC) design standards with the American Petroleum Institute (API) recommended practices. Offshore wind farms that are operating in Europe have been designed using standards developed specifically for offshore wind, such as those developed by Germanischer Lloyd (GL) and Det Norske Veritas (DNV). The IEC has recently drafted design requirements specifically for offshore wind farms that provides a comprehensive definition of load conditions and references other standards, where needed, to provide a complete guidance document. The intent of this paper is to examine the range of applicability of the various design standards and to assess how these standards apply to the design of U.S. offshore wind turbine (OWT) support structures.
Critical Aspects to the Design and Installation of Top Tensioned Risers
Authors: Westlake Andy , Quinn Ronan
Published: May 2009

Dual and single casing top tensioned risers are widely used by operators for deepwater floating production facility developments. These riser types provide direct vertical access for completions and workover. These single and dual barrier risers are a stable riser concept utilizing the effective tension distribution between casings and tubing to mitigate any collapse or buckling concerns. However the interaction and load paths of these riser strings are quite complex and require careful planning and analysis to ensure safe installation and design. This paper will outline various TTR configurations and will consider the effects of various loads on the riser string, while identifying the respective load paths that determine critical riser components for extreme and fatigue loading. This paper will provide guidance on how to model the various tensioning systems for TTR application, as well as the associated platform guide surfaces and casings, and will help to identify some of the pitfalls in simplifying this procedure. The paper also highlights some of the operational difficulties involved in the installation of TTRs and will present a methodology to make ad-hoc adjustments to the space-out as necessary. This paper will attempt to build on previous technical papers on the subject and introduce some relevant lessons learned at both design an installation phase of projects.
Thermal Ageing Effects on Thickwalled Line Pipe
Authors: Hines Josh R. , Timms Chris M. , DeGeer Duane D.
Published: May 2009

Line pipe is often coated prior to installation in order to achieve some protection against the environment. Many of the coatings used today require the pipe to not only be cleaned and degreased, but also to be preheated to a temperature of 200–240°C during application of the coating material. A typical coating thermal cycle involves rapid heating of the pipe using induction coils, application of the coating, and quenching to cool the pipe for handling purposes. It is generally understood that this thermal treatment on UOE line pipe, which can last from a couple to as many as ten minutes, has an effect on the pipe yield and, to a lesser extent, tensile strength. For ultra-deepwater offshore applications, where collapse is often the controlling design case, the increase in hoop-compressive yield strength is viewed as desirable because of the corresponding increase in collapse pressure. For onshore applications, however, bending due to differential ground movements can be the primary design consideration. In this case, an increase in tensile yield strength in the longitudinal direction may occur, and may result in a higher Y/T ratio. This increased Y/T can reduce the critical buckling strain of a pipeline designed to this limit state. In this paper, the effects of a coating thermal treatment on X70 grade UOE line pipe material properties are presented with particular attention being paid to the effect on the hoop-compressive and axial tensile yield as well as Y/T ratio. Both coating mill and coupon scale thermal treatment were investigated. Comparison was made between full thickness and round bar axial tensile samples. In addition, the influence of over-ageing or extended duration heating is investigated with respect to its impact on strength and ductility as well as the Charpy impact properties. Results of this study indicate increases between 13 and 16% for hoop-compressive yields while increases in the axial direction were approximately half that magnitude. Y/T ratio increases of around 5% were seen in the axial direction. The over ageing study did not demonstrate any detrimental effect of extended duration thermal treatment on the tested material properties.
The Second Order Statistics of High Waves in Wind Sea and Swell
Authors: Tromans Peter , Vanderschuren Luc , Ewans Kevin
Published: May 2009

The statistics of extreme wave crest elevation and wave height have been calculated for realistic, directionally spread sea and swell using a probabilistic method tested and described previously. The non-linearity of steep waves is modelled to second order using Sharma and Dean kinematics and a response surface (reliability type) method is used to deduce the crest elevation or wave height corresponding to a given probability of exceedance. The effects of various combinations of sea and swell are evaluated. As expected, in all cases, non-linearity makes extreme crests higher than the corresponding linear ones. The non-linear effects on wave height are relatively small.
How Risky Were My Old Platforms?
Authors: Marshall Peter W.
Published: May 2009

API RP2A, 21st edition recognizes several consequence-based levels of platform design or assessment. L-1 gives critical new platforms a level of reliability almost comparable to continuously manned platforms in the North Sea, and the economic impact of their failure risk essentially vanishes. L-2 is used for manned-evacuated platform, gives a finite but still low level of risk based on economic trade-offs; it has served the Gulf of Mexico industry well for three decades. Re-assessment criteria are lower in terms of metocean loading, and accept more risk, because upgrading platforms in place is an order of magnitude more expensive than adding a little beef to a new-build. Assessment level A-1 is for well-maintained platforms built to “100-year” metocean criteria of the 1960s, but still serving vital functions, e.g. pipeline hubs, where the business interruption risk they pose to upstream producers can be considerable. A-2 simply provides for personnel safety in case a sudden (but weak) hurricane precludes evacuation; economic consequences are left for the operator to evaluate. Levels L-3 and A-3 are reserved for unmanned structures whose collapse does not even have significant economic consequence. It is presumed that high-reliability SCSSVs will prevent pollution in any case. The existing A-2 level is substantially weaker than L-2. It is suitable for production platforms on stripper-well status under the philosophy of “Produce until it falls down,” which makes more sense than arbitrarily abandoning the production prematurely. However, the risk of an old A-2 platform (or a cluster of them in the same field) failing before another decade is out has been estimated to be as high as 25% to 45%. This puts structural risk right up there with reservoir and price uncertainties, deserving consideration in the venture evaluation stage. Mitigation strategies, e.g. plugging depleted wells while they are still upright, also deserve consideration. This paper will examine these structural risks in light of existing standards, based on earlier criteria studies. The API-2INT series of Interim standards, currently under development based on HEAT (Hurricane Evaluation and Assessment Team) work, will be the subject of future presentations.
Modeling of the Indian Ocean Tsunami
Authors: Behera Manasa Ranjan , Murali K. , Sundar V.
Published: May 2009

Shallow Water Equations are solved using an Unstructured Explicit Finite Element Method (UEFEM) to simulate long waves in the ocean. The formulation of the UEFEM has been described and found to be computationally efficient for large problems such as basin level modeling of tsunamis. Different domains have been considered to simulate the propagation of the waves due to an artificially imposed initial disturbance. The domain of Bay of Bengal has been considered for simulation with an initial disturbance which resembles the type and location of the 2004 Indian Ocean Tsunami. The Wave elevation and deformations as well as time of travel of tsunami are reproduced. The method hence has high potential of being attractive for application of simulation of global tsunamis.
Rapid Preliminary Design of Floating Offshore Structures Using a Modified Genetic Algorithm
Authors: Perry Michael J. , Halkyard John E. , Koh C. G.
Published: May 2009

Preliminary design of floating offshore structures involves determining structural dimensions able to provide sufficient buoyancy to carry the required topside, at the lowest possible cost, while satisfying various stability, strength, installation, and response requirements. A novel optimization strategy, capable of carrying out the preliminary design of floating offshore structures, is presented in this paper. The genetic algorithm based strategy searches within prescribed parameter limits for the most cost effective design, while ensuring the design conforms to the constraints given. The design of a truss spar is used to illustrate how the strategy can be applied. The topside weight, design wind speed, maximum wave height, etc are input along with constraints such as, maximum draft at floatoff, maximum heel angle, allowable stress in the truss and limits on pitch and heave period and response. Using empirical estimates for hull weights and simplified response calculations, the strategy is then able to rapidly determine parameters such as hull diameter, hard tank depth, length of keel tank, total length and truss leg diameter such that the total cost of the structure is minimized. The strategy allows for the preliminary design phase to be completed in only a few seconds, while providing initial weight and cost estimates.
Response Characteristics of a Multi-Connected Floating Body System in Waves
Authors: Ikegami Kunihiro , Matsuura Masami , Wada Yuki , Zhang Guo
Published: May 2009

A multi-connected floating body system composed of many connected small-scale floating body units has a number of advantages with regard to construction and performance compared with a united floating body. To design the multiconnected floating body system, it is necessary to grasp the exact response characteristics of the multi-connected floating body system in waves. A model basin test and a theoretical calculation were conducted for the multi-connected floating body system in waves. In the model basin test, three floating body unit models with a regular hexagonal water plane were connected to each other with a newly conceived mechanical connecting device. As a result, the response characteristics of the multi-connected floating body system in waves were clarified experimentally and theoretically, and the applicability of a theoretical calculation method was experimentally confirmed.
An Inverse Finite Element Strategy to Recover Full-Field, Large Displacements From Strain Measurements
Authors: Paczkowski Krystian , Riggs H. R.
Published: May 2009

In active control of structures, it may be necessary to determine real-time displacements from measured deformations. Recently an inverse finite element method, iFEM, has been proposed to recover ‘small’ displacement fields for plate and shell structures from (small) strain measurements. A procedure to handle large displacements and nonlinear strains is presented in this paper. A similar least-squares error functional as in linear iFEM is used, but the linear strains are replaced with the Green-Lagrange strains, and a ‘total Lagrangian’ formulation is developed. As in the linear iFEM, the focus is again principally towards plate and shell structures. The functional is minimized with the finite element method. The nonlinear iFEM formulation is presented in detail and applied to a cantilever beam undergoing very large displacements. The relatively simple example is used to explore the formulation’s performance to recover large displacements. The results indicate that the approach is able to recover the large displacement field. Additional work is required to develop the method for practical application.
A Comparison of the Surface Extrapolation and Battelle Structural Stress Methodologies as Applied to a Spectral Fatigue Analysis of a Representative FPSO Structural Detail
Authors: Healy Brian E.
Published: May 2009

A spectral fatigue analysis using both the surface extrapolation and Battelle structural stress methodologies has been performed on a side shell connection detail typical of a representative FPSO or tanker vessel. This marks the first time the Battelle method has been adapted to spectral fatigue and details of the implementation are presented for narrow banded applications. Fatigue damage at the toe along a number of weld lines is computed for a variety of surface extrapolation strategies and Battelle method options. Results are reported and compared. Recommendations regarding the application of the Battelle method to spectral fatigue are made.
Efficient Time-Domain Simulation of Side-By-Side Moored Vessels Advancing in Waves
Authors: Chitrapu A. S. Murthy , Mordfin Theodore G. , Chance Henry M.
Published: May 2009

Evaluation of hydrodynamic performance of two vessels in close proximity that are either stationary or advancing in waves is of paramount importance for many offshore and naval engineering applications. Hydrodynamic interactions between the vessels combined with nonlinear mechanical interactions due to mooring and fendering systems make the problem more complicated. An efficient time-domain method is presented for evaluating the seakeeping and maneuvering performance of proximate vessels advancing with forward speed. The method computes the 6 degree-of-freedom motions of a pair of hydrodynamically interacting vessels subject to wind, waves, currents and maneuvering effects at zero and nonzero speeds in regular or random seaways. Model tests conducted to validate the method are described and results presented. The validation efforts conducted so far have yielded satisfactory comparisons, thereby reinforcing the confidence in the method and its applicability to such problems. The method has been used to predict safe operational limits of two vessels in skin-to-skin operations conducted by the US Navy. A similar analysis is presented herein for a different pair of vessels. Since it is based on time domain simulation, this method also allows the inclusion of non-linear effects due to mooring lines, fenders and effects of viscous roll damping, which is not possible with two-body hydrodynamic interaction solutions in frequency-domain. It is concluded that this method provides an efficient tool to predict the performance of hydrodynamically interacting vessels that are stationary or moving with forward speed. To date, it has proven very useful in the early stages of the design/concept development process in which many configurations are evaluated.
Design and Construction Considerations for Offshore Wind Turbine Foundations
Authors: Malhotra Sanjeev
Published: May 2009

With the growing energy needs of the world and the sustainable nature of wind energy this sector is a highly innovative growth industry. The past years have seen the industry develop and test not only more efficient, but also much larger wind turbines than those that are in current use. The next generation of wind turbines that are on the drawing boards are gigantic in size. These huge dimensions of the proposed wind turbines will put large demands on the foundations. As an increasing number of wind farms are being planned offshore in water depths of over 40 m, the combination of water depth and the increased windmill tower heights and rotor blade diameters create loads that make foundation design very complex. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ship impact loads. All of these factors pose significant challenges in the design and construction of wind turbine foundations. This paper presents the various issues facing the designer in designing and constructing wind turbine tower foundations. Current practices are summarized to assist developers in foundation type selection and design.
Evaluation of the dose calculation accuracy in intensity‐modulated radiation therapy for mesothelioma, focusing on low doses to the contralateral lung
Authors: Court Laurence E , Ching David , Schofield Deborah , Czerminska Maria , Allen Aaron M
Published: May 2009

This study compares Monte Carlo (MC) with conventional treatment planning system (TPS) calculations. The EGS4nrc MC code, BEAMnrc, was commissioned to simulate a Varian 21Ex Linac. The accuracy of the simulations, including points blocked by the jaws, was evaluated by comparing MC with ion chamber and MOSFET measurements. Eight mesothelioma IMRT cases were planned using Eclipse (pencil beam and superposition convolution algorithms). Dose distributions were recalculated using BEAMnrc/DOSxyz, and compared with TPS. MC agreed with experimental results for IMRT fields within 3% (96% of points). For regions blocked by the jaws, average agreement between MC and experiment was better than 5% up to 20 cm from isocenter. The pencil beam algorithm underestimated lung MLD, V20, and V5, compared with MC, by a mean (range) of 16% (11–22%), 9.0% (2.4 – 30.1%), and 11.8% (2 – 30%), respectively. The superposition convolution algorithm gave better agreement of 8.5% (0 – 17%), 4% (0 – 12%) and 0% (–6 – 6%). Mean dose to the targets was better than in all cases. In conclusion, there is excellent correlation between TPS and MC calculations for the target doses. The pencil beam algorithm and superposition convolution algorithms both underestimate lung dose parameters, but the superposition convolution dose offers improvements in dose calculation accuracy for these patients.

PACS number: 87.55.kh, 87.55.dk, 87.55.Qr
Radiation survey around a Liac mobile electron linear accelerator for intraoperative radiation therapy
Authors: Ciocca Mario , Pedroli Guido , Orecchia Roberto , Guido Andrea , Cattani Federica , Cambria Raffaella , Veronesi Umberto
Published: May 2009

The aim of this study was to perform a detailed analysis of the air kerma values around a Liac mobile linear accelerator working in a conventional operating room (OR) for IORT.

The Liac delivers electron beams at 4, 6, 8 and 10 MeV. A radiation survey to determine photon leakage and scatter consisted of air kerma measurements on a spherical surface of 1.5 m radius, centered on the titanium exit window of the accelerating structure. Measurements were taken using a 30 cm3 calibrated cylindrical ion chamber in three orthogonal planes, at the maximum electron energy. For each point, 10 Gy was delivered. At selected points, the quality of x‐ray radiation was determined by using lead sheets, and measurements were performed for all energies to investigate the energy dependence of stray radiation. The photon scatter contribution from the metallic internal patient‐shielding in IORT, used to protect normal tissues underlying the target, was also evaluated. At seven locations outside the OR, the air kerma values derived from in‐room measurements were compared to measurements directly performed using a survey meter. The results, for a delivered dose of 10 Gy, showed that the air kerma values ranged from approximately 6 μGy (upper and rear sides of the Liac) to 320 μGy (lateral to beam stopper) in the two orthogonal vertical planes, while values lower than 18 μGy were found in the horizontal plane. At 10 MeV, transmission behind 1 cm lead shield was found to be 42%. The use of internal shielding appeared to increase the photon scatter only slightly. Air kerma values outside the OR were generally lower than 1 mGy for an annual workload of 200 patients. Thus, the Liac can safely work in a conventional OR, while the need for additional shielding mainly depends on patient workload. Our data can be useful for centers planning to implement an IORT program using a mobile linear accelerator, permitting radiation safety personnel to estimate in advance the shielding required for a particular workload.

PACS number: 87.55.ne, 87.56.bd
Germline P Granules Are Liquid Droplets That Localize by Controlled Dissolution/Condensation
Authors: Brangwynne Clifford P. , Eckmann Christian R. , Courson David S. , Rybarska Agata , Hoege Carsten , Gharakhani Jöbin , Jülicher Frank , Hyman Anthony A.
Published: May 2009

P Granule Conundrum

In many organisms, the presumptive germ cells can be distinguished from somatic cells by the presence of distinctive cytoplasmic granules. In
Caenorhabditis elegans
, these P granules are more or less uniformly distributed in the oocyte and one-cell stage of the fertilized egg. By the end of the first cleavage, however, the anterior cell is essentially free of P granules, whereas the posterior cell still displays a prominent population of granules. Exactly how this process occurs and whether it involves directed migration of the granules is unclear. Now

Brangwynne
et al.

(p.
1729
, published online 21 May; see the Perspective by

Le Goff and Lecuit

) provide evidence that localization occurs by a quite different mechanism, controlled dissolution and condensation of granule components. This type of cytoplasmic remodeling by physicochemical mechanisms can now be looked for in other cellular and developmental systems.
Efficacy and safety of comfrey root extract ointment in the treatment of acute upper or lower back pain: results of a double-blind, randomised, placebo controlled, multicentre trial
Authors: Giannetti B M , Staiger C , Bulitta M , Predel H-G
Published: May 2009

Objective

The objective was to show the superiority of comfrey root extract ointment to placebo ointment in patients with acute upper or lower back pain.

Design

The study was conducted as a double-blind, multicentre, randomised clinical trial with parallel group design over a period of 5 days (SD 1). The patients (n = 120, mean age 36.9 years) were treated with verum or placebo ointment three times a day, 4 g ointment per application. The trial included four visits.

Main Outcome Measures

The primary efficacy variable was the area under the curve (AUC) of the visual analogue scale (VAS) on active standardised movement values at visits 1 to 4. The secondary efficacy variables were back pain at rest using assessment by the patient on VAS, pressure algometry (pain–time curve; AUC over 5 days), global assessment of efficacy by the patient and the investigator, consumption of analgesic medication and functional impairment measured using the Oswestry disability index.

Results

There was a significant treatment difference between comfrey extract and placebo regarding the primary variable. In the course of the trial the pain intensity on active standardised movement decreased on average (median) approximately 95.2% in the verum group and 37.8% in the placebo group.

Conclusions

The results of this clinical trial were clear-cut and consistent across all primary and secondary efficacy variables. Comfrey root extract showed a remarkably potent and clinically relevant effect in reducing acute back pain. For the first time a fast-acting effect of the ointment (1 h) was also witnessed.
EXTRA DIMENSIONS WITH NONTRIVIAL TORSION AND SPINS OF COSMIC STRINGS
Authors: CAO ZHEN-BIN , DUAN YI-SHI
Published: May 2009

As two generalizations of Einstein's general relativity, the nontrivial spacetime torsion and the compact extra dimensions have been largely studied in the literature. In this paper, by combining a torsioned Kaluza–Klein scheme and the field-theory cosmic string theory, we discuss that a higher-dimensional torsion component can be expressed in terms of the usual four-dimensional field strength two-form, and this torsion form can then get trapped into the cores of the cosmic strings and further relate to the intrinsic spins of the strings.
FLUID AND STRUCTURAL ANALYSIS OF A LARGE DIAMETER BUTTERFLY VALVE
Authors: SONG XUE GUAN , WANG LIN , PARK YOUNG CHUL
Published: May 2009

A butterfly valve of large diameter is commonly used as control equipments in applications where the inlet velocity is fast and the pressure is relatively high. Because the size of the valve is too large, it's too difficult to conduct testing experiment in a laboratory. In this paper, the numerical simulation using commercial package-CFX and ANSYS was conducted. In order to perform fluid analysis and structural analysis perfectly, large valve models are generated in three dimensions without much simplification. The result of fluid analysis is imported to structure analysis as a boundary condition. In addition, to describe the flow patterns and to measure the performance when valve are opened for various angles, the verification of the performance whether the valve could work safely at these different conditions or not was conducted. Fortunately, the result shows that the valve is safe in a given inlet velocity of 3 m/s, and it's not necessary to be strengthened anywhere. In the future, the shape of valve disc can be optimized to reduce the weight, and also to make the flow coefficient be closer to the suggested level.
IMAGE DENOISING BASED ON THE DYADIC WAVELET TRANSFORM AND IMPROVED THRESHOLD
Authors: HUANG ZHENGHONG , FANG BIN , HE XIPING , XIA LI
Published: May 2009

Wavelet transform has shown a strong capability to filter out noise that existed in images. The main problem to improve denoising performance lies in the fact that it is difficult to select suitable wavelet transform and related thresholds. In this paper, we completely explore characteristics of dyadic wavelet transform and its possible use to image denoising. An improved threshold method is elaborately designed to establish the self-adjusted layer threshold function and wavelet reconstruction. Theoretical analysis shows that denoising precision can be improved by way of adopting different thresholds according to the different scales of the wavelet coefficients of image and noise. Experiment results demonstrated that our method is obviously superior to that of fixed threshold regarding the effect of image denoising.
Carbon monoxide, skeletal muscle oxidative stress, and mitochondrial biogenesis in humans
Authors: Rhodes Michael A. , Carraway Martha Sue , Piantadosi Claude A. , Reynolds Crystal M. , Cherry Anne D. , Wester T. E. , Natoli Michael J. , Massey E. Wayne , Moon Richard E. , Suliman Hagir B.
Published: May 2009

Given that the physiology of heme oxygenase-1 (HO-1) encompasses mitochondrial biogenesis, we tested the hypothesis that the HO-1 product, carbon monoxide (CO), activates mitochondrial biogenesis in skeletal muscle and enhances maximal oxygen uptake (V̇o2max) in humans. In 10 healthy subjects, we biopsied the vastus lateralis and performed V̇o2max tests followed by blinded randomization to air or CO breathing (1 h/day at 100 parts/million for 5 days), a contralateral muscle biopsy on day 5, and repeat V̇o2max testing on day 8. Six independent subjects underwent CO breathing and two muscle biopsies without exercise testing. Molecular studies were performed by real-time RT-PCR, Western blot analysis, and immunochemistry. After V̇o2max testing plus CO breathing, significant increases were found in mRNA levels for nuclear respiratory factor-1, peroxisome proliferator-activated receptor-γ coactivator-1α, mitochondrial transcription factor-A (Tfam), and DNA polymerase γ (Polγ) with no change in mitochondrial DNA (mtDNA) copy number or V̇o2max. Levels of myosin heavy chain I and nuclear-encoded HO-1, superoxide dismutase-2, citrate synthase, mitofusin-1 and -2, and mitochondrial-encoded cytochrome oxidase subunit-I (COX-I) and ATPase-6 proteins increased significantly. None of these responses were reproduced by V̇o2max testing alone, whereas CO alone increased Tfam and Polγ mRNA, and COX-I, ATPase-6, mitofusin-2, HO-1, and superoxide dismutase protein. These findings provide evidence linking the HO/CO response involved in mitochondrial biogenesis in rodents to skeletal muscle in humans through a set of responses involving regulation of the mtDNA transcriptosome and mitochondrial fusion proteins autonomously of changes in exercise capacity.
Increased myocardial NAD(P)H oxidase-derived superoxide causes the exacerbation of postinfarct heart failure in type 2 diabetes
Authors: Matsushima Shouji , Kinugawa Shintaro , Yokota Takashi , Inoue Naoki , Ohta Yukihiro , Hamaguchi Sanae , Tsutsui Hiroyuki
Published: May 2009

Type 2 diabetes adversely affects the outcomes in patients with myocardial infarction (MI), which is associated with the development of left ventricular (LV) failure. NAD(P)H oxidase-derived superoxide (O2−) production is increased in type 2 diabetes. However, its pathophysiological significance in advanced post-MI LV failure associated with type 2 diabetes remains unestablished. We thus hypothesized that an inhibitor of NAD(P)H oxidase activation, apocynin, could attenuate the exacerbated LV failure after MI in high-fat diet (HFD)-induced obese mice with type 2 diabetes. Male C57BL/6J mice were fed on either HFD or normal diet (ND) for 8 wk. At 4 wk of feeding, MI was created in mice by ligating the left coronary artery. HFD-fed MI mice were treated with either 10 mmol/l apocynin or vehicle. HFD + MI had significantly greater LV end-diastolic diameter (LVEDD; 5.7 ± 0.1 vs. 5.3 ± 0.2 mm), end-diastolic pressure (12 ± 2 vs. 8 ± 1 mmHg), and lung weight/tibial length (10.1 ± 0.3 vs. 8.7 ± 0.7 mg/mm) than ND + MI, which was accompanied by an increased interstitial fibrosis of noninfarcted LV. Treatment of HFD + MI with apocynin significantly decreased LVEDD (5.4 ± 0.1 mm), LV end-diastolic pressure (9.7 ± 0.8 mmHg), lung weight/tibial length (9.0 ± 0.3 mg/mm), and concomitantly interstitial fibrosis of noninfarcted LV to the ND + MI level without affecting body weight, glucose metabolism, and infarct size. NAD(P)H oxidase activity and O2− production were increased in noninfarcted LV tissues from HFD + MI, both of which were attenuated by apocynin to the ND + MI level. Type 2 diabetes was associated with the exacerbation of LV failure after MI via increasing NAD(P)H oxidase-derived O2−, which may be a novel important therapeutic target in advanced heart failure with diabetes.
Neuromuscular recovery pattern after medial collateral ligament disruption in rats
Authors: Laurin Jérôme , Dousset Erick , Mesure Serge , Decherchi Patrick
Published: May 2009

The medial collateral ligament (MCL) is one of the most injured ligaments during sport activities. The resulting joint damage effects on neuromuscular system remain unclear. Thus this study was designed to assess the changes in neuromuscular properties of vastus medialis muscle after MCL transection. Complete rupture of MCL was performed on rats, and dynamic functional assessment during locomotion was achieved before and once a week from 1–5 wk postlesion. Twitch properties and metabo- and mechanosensitive afferent fiber responses to specific stimuli were measured 1, 3, and 5 wk after MCL transection. Results indicated that maximum knee angle measured during the stance phase of the gait cycle was decreased during 3 wk after MCL injury and then recovered. Minimum knee angle measured during the stance phase was decreased during 2 wk and showed compensatory effects at week 5. A stepwise decrease in maximum relaxation rate-to-amplitude ratio concomitant with a stepwise increase in half-relaxation time were observed following MCL injury. Variations in metabosensitive afferent response to chemical (KCl and lactic acid) injections were decreased at week 1 and recovered progressively from week 3 to week 5 postlesion. Recovery of the mechanosensitive afferent response to vibrations was not totally complete after 5 wk. Our data indicate that alteration of the sensory pathways from the vastus medialis muscle could be considered as a source of neuromuscular deficits following MCL transection. Our results should be helpful in clinical purpose to improve the knowledge of the influence exerted by ligament rupture on the motor system and permit development of rehabilitation protocols and exercises more appropriate for recovery of functional stability.