bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact Tests in Pure and Aerated Water
Authors: Lange Niels A. , Rung Thomas
Published: November 2011

Impact loads due to slamming or ditching are an important issue in marine and aircraft engineering. Accordingly, many experimental, theoretical and numerical investigations have been performed. The paper reports the build-up of a test rig, which was designed to study vertical guided motion impact tests, and the results of an experimental study on impact loads into pure and aerated water. Attention is given to the loads experienced by a rigid circular-cylinder section (diameter = 0.2 m, length = 0.5 m) during guided, constant-speed impact. The investigations involve a variety of entry speeds up to 3m/s and gas-content levels. The obtained data offers a basis for an analysis of the sensitivity of the impact loads on the gas content. Fair compliance with literature reported experimental and theoretical results — using e.g. von Ka´rma´n or Wagner theories — has been obtained for pure water impact loads. For impact tests in aerated water, a significant reduction of the measured pressure peaks becomes apparent. Finally, the paper illustrates the feed back of the experimental results into an impact-load model, taking the fluid compressibility into account.
Study on the Hot Spot Stress Distribution at Multi-Planar Tubular KK Joints Under Axial Loads
Authors: Yue Jingxia , Gan Jin , Wu Weiguo , Zhai Shihong , Yang Yanhua
Published: November 2011

The Hot Spot Stress (HSS) distribution around welded tubular joints in truss legs is essential information for the fatigue assessment of jack-up platforms. Both Finite Element (FE) analysis and model test were carried out on a multi-planar tubular KK joints under asymmetric axial loads in our research. The study shows that the HSS distribution around welded joints is different from common K or T joints, and the maximum HSS appears between crown and saddle on the chord surface at the chord-brace intersection. Moreover, some sensitive factors which influence the locations of the maximum HSS were investigated by FEA in this paper. The analysis results are useful for the optimal structure designing and crack initial prediction of the offshore jack-up platforms legs.
Vertical Position Control for Top Tensioned Riser With Active Heave Compensator
Authors: Leira Bernt J. , Fang Shaoji , Blanke Mogens
Published: November 2011

The top and bottom angles of a marine riser are of crucial importance during e.g. drilling and workover operations. A vertical position control with active heave compensator (AHC) is proposed to maintain the safety of the riser when subjected to environmental excitations. The possibility of reducing the maximum angular response level by adjusting the vertical rod position by means of an active heave compensator is investigated with a positioning algorithm based on adaptive backstepping. Riser top and bottom angles are dealt with by the algorithm in order to minimize both angles.
Response Behaviour of Perforated Cylinders in Regular Waves
Authors: Chandrasekaran Srinivasan , Pandian S. Parameswara
Published: November 2011

In order to reduce the direct wave impact, coastal and offshore structures are often constructed with one or more perforated layers. Several permeable breakwaters and docks have been deployed in coastal protection measures to reduce direct impact due to encountered wave loads and to reduce wave reflection in front of these structures as well; compared with the traditional ones, such structural forms are found to be more economical. Such structures result in lesser surface fluctuation in harbours due to the low reflection, which is vital for loading and unloading of ships. Deploying permeable breakwaters posses other advantages namely: i) increasing water circulation; ii) retaining water quality and iii) enhances coastal protection. Emerged and submerged perforated cylindrical structures reduce wave-structure interactions and scouring problems considerably, but their use on floating structures is scarce in the literature. This study is focused on detailed experimental investigations carried out on impermeable inner cylinder encompassed by a larger outer cylinder with perforatios along its length. By varying the porosity and perforatio diameter, their influence on the hydrodynamic response of the cylindrical member is highlighted through the current study. The conclusions on the comparison of forces in the cylinder with and without perforated cylinder coverage are presented.
Stress Analysis of a Cryogenic Corrugated Pipe
Authors: Srivastava Vikas , Buitrago Jaime , Slocum Scott T.
Published: November 2011

One method to develop offshore gas reserves is to use a floating LNG plant (FLNG) on site and export the LNG via tankers. This alternative requires the use of a reliable LNG transfer system between the FLNG and the tanker under offshore conditions. One such system involves a flexible cryogenic hose whose main body is a pipe-in-pipe hose made of two concentric corrugated 316L stainless steel pipes (C-pipe) with flanged terminations. Thermal insulation is achieved by maintaining vacuum between the inner and outer corrugated stainless steel pipes. In addition, the hose assembly contains two outer layers of helical armor wires to sustain the axial load. Given the complexity and novelty of the transfer system, a finite element study was performed on the inner C-pipe — the critical fluid containment layer. The effects of strain hardening of corrugations due to cold forming and temperature were modeled. Finite element (FE) analyses of the C-pipe under axial, bending, and internal pressure loading were carried out to evaluate global load-deformation and local stress responses. Comparisons of full-scale tests at room and cryogenic temperatures to simulation predictions including the novel material model showed good agreement. However, fatigue life predictions for the C-pipe that were based on local stresses and sheet metal fatigue S-N curves did not agree with the full-scale fatigue test results. The results indicated that the spatial variation in strain hardening due to corrugation forming and biaxial local stresses during pipe deformation could play important roles in the fatigue response of the C-pipe.
Extremes of Nonlinear Vibration: Models Based on Moments, L-Moments, and Maximum Entropy
Authors: Winterstein Steven R. , MacKenzie Cameron A.
Published: November 2011

Nonlinear effects beset virtually all aspects of offshore structural loading and response. These nonlinearities cause non-Gaussian statistical effects, which are often most consequential in the extreme events—e.g., 100- to 10,000-year conditions—that govern structural reliability. Thus there is engineering interest in forming accurate non-Gaussian models of time-varying loads and responses, and calibrating them from the limited data at hand. We compare here a variety of non-Gaussian models. We first survey moment-based models; in particular, the 4-moment “Hermite” model, a cubic transformation often used in wind and wave applications. We then derive an “L-Hermite” model, an alternative cubic transformation calibrated by the response “L-moments” rather than its ordinary statistical moments. These L-moments have recently found increasing use, in part because they show less sensitivity to distribution tails than ordinary moments. We find here, however, that these L-moments may not convey sufficient information to accurately estimate extreme response statistics. Finally, we show that 4-moment maximum entropy models, also applied in the literature, may be inappropriate to model broader-than-Gaussian cases (e.g., responses to wind and wave loads).
On the Estimation of Ocean Engineering Design Contours
Authors: Jonathan Philip , Ewans Kevin , Flynn Jan
Published: November 2011

Understanding extreme ocean environments and their interaction with fixed and floating structures is critical for offshore and coastal design. Design contours are useful to describe the joint behaviour of environmental, structural loading and response variables. We compare different forms of design contours, using theory and simulation, and present a new method for joint estimation of contours of constant exceedence probability for a general set of variables. The method is based on a conditional extremes model from the statistics literature, motivated by asymptotic considerations. We simulate under the conditional extremes model to estimate contours of constant exceedence probability. We also use the estimated conditional extremes model to estimate other forms of design contours, including those based on the First Order Reliability Method, without needing to specify the functional forms of conditional dependence between variables. We demonstrate the application of new method in estimation of contours of constant exceedence probability using measured and hindcast data from the Northern North Sea, the Gulf of Mexico and the North West Shelf of Australia, and quantify their uncertainties using a bootstrap analysis.
Radar Measurement of Ocean Waves
Authors: Story W. Rob , Fu Thomas C. , Hackett Erin E.
Published: November 2011

Over the past two decades a number of advances have been made in the use of radar systems for the measurement of ocean waves, building on early work at universities and the Naval Research Lab (NRL) to investigate the potential for extracting wave field measurements from the sea clutter seen in shipboard radar images. This early work was the foundation for modern wave radar systems, with hardware systems ranging from commercial off the shelf (COTS) incoherent navigation radar to specially developed, calibrated, coherent instrumentation radar and phased-array systems. Software algorithms and image analysis techniques have also been in constant development, which have evolved from 2D analysis of digitized images into modern techniques performing real-time 3D transformation of high resolution images. Most of these systems are being utilized to measure the directional wave spectra, with some systems also providing wave height estimates and sea surface elevation maps. More recently, the Naval Surface Warfare Center, Carderock Division (NSWCCD) and others have begun to utilize these techniques for shipboard measurement of open ocean waves. All these efforts have led to higher fidelity data, as well as data that were previously unobtainable. In this paper we provide an overview and history of the development of COTS incoherent wave radar systems, analysis techniques, and capabilities, from early characterization of sea clutter return to the latest developments in image inversion and sea surface topography. This review and summary provides a foundation on which to develop analysis techniques for the higher fidelity data, using lessons learned to improve future analysis. While not intending to be exhaustive, this paper seeks to highlight the insights gained from both historical and recent applications of these techniques, as well as the difficulties and issues associated with shipboard measurements such as ship motion, logistical constraints, and environmental factors.
Relative Notch Factor for Tubular Joint Stress Concentration Under High Load
Authors: Zhao Wangwen
Published: November 2011

When load causes stress above the yielding stress, stress concentration factor from linear conditions can no longer be applied. Neuber’s rule has been traditionally used to estimate the non-linear stress concentration factors to avoid elaborate numerical analysis. However, the multiaxial stress state around the tubular intersection has been found to be too complex for Neuber’s rule to be applied directly. To facilitate calculation of non-linear stress concentration for tubular intersection, this paper proposed an effective relative notch factor for tubular connection stress concentration based on available linear stress concentration factors and fatigue experimental studies. This approach is validated by detailed FE analysis for three representative tubular joint configurations, two T joints and one Y joint. It has been found that although the stress states are different from typical notch specimen, the modified Neuber’s method using notch stress concentration factors Kt = Ktn as a product of tubular hot spot SCF and relative notch factor of 1.53 matches true stress closely initially but progressively become less and less accurate. When the applied load is about 70% of the plastic collapse load, the method give 30% under prediction at the worst case. This may be due to unaccounted non-linear effect from local buckling and excessive plasticity.
Tidal Turbine Blade Selection for Optimal Performance in an Array
Authors: Nicholls-Lee Rachel F. , Turnock Stephen R. , Boyd Stephen W.
Published: November 2011

In order to maximize tidal energy capture from a specific site free stream devices are situated in arrays. In an array the downstream evolution of the wake generated by a rotating tidal energy conversion device influences the performance of the device itself, the bypass flow to either side as well as the performance of any downstream device. As such it is important to design a turbine that can perform efficiently and effectively in these circumstances. Use of passively adaptive composite blades for horizontal axis tidal turbines has been shown to improve performance in fluctuating inflows. Active adaptation and/or bi-directional hydrofoil sections could be implemented in order to optimize performance throughout the tidal cycle. This paper considers the performance in an array of four free stream turbines implementing standard rigid blades, wholly bidirectional blades, passively adaptive blades and actively adaptive blades. The method used to evaluate the performance of tidal current turbines in arrays couples an inner domain solution of the blade element momentum theory with an outer domain solution of the Reynolds averaged Navier Stokes equations. The annual energy capture of four devices with each blade type in a staggered array is then calculated for a single tidal cycle and compared.
Mechanical Qualification of Dynamic Deep Water Power Cable
Authors: Slora Roger , Karlsen Stian , Osborg Per Arne
Published: November 2011

There is an increasing demand for subsea electrical power transmission in the oil- and gas industry. Electrical power is mainly required for subsea pumps, compressors and for direct electrical heating of pipelines. The majority of subsea processing equipment is installed at water depths less than 1000 meters. However, projects located offshore Africa, Brazil and in the Gulf of Mexico are reported to be in water depths down to 3000 meters. Hence, Nexans initiated a development programme to qualify a dynamic deep water power cable. The qualification programme was based on DNV-RP-A203. An overall project plan, consisting of feasibility study, concept selection and pre-engineering was outlined as defined in DNV-OSS-401. An armoured three-phase power cable concept assumed suspended from a semi-submersible vessel at 3000 m water depth was selected as qualification basis. As proven cable technology was selected, the overall qualification scope is classified as class 2 according to DNV-RP-A203. Presumed high conductor stress at 3000 m water depth made basis for the identified failure modes. An optimised prototype cable, with the aim of reducing the failure mode risks, was designed based on extensive testing and analyses of various test cables. Analyses confirmed that the prototype cable will withstand the extreme loads and fatigue damage during a service life of 30 years with good margins. The system integrity, consisting of prototype cable and end terminations, was verified by means of tension tests. The electrical integrity was intact after tensioning to 2040 kN, which corresponds to 13 000 m static water depth. A full scale flex test of the prototype cable verified the extreme and fatigue analyses. Hence, the prototype cable is qualified for 3000 m water depth.
Fluctuation of High-Turbidity Water Measured by Acoustic Doppler Current Profiler at the Izena Calderon in the Okinawa Trough
Authors: Arai Rei , Onobayashi Yusuke , Ishida Hiroshi , Maeda Nobuhiro , Sugimoto Tomoya , Sirayama Yoshihisa , Toyohara Tetsuhiko , Goto Nobuhiro
Published: November 2011

Hydrothermal processes associated with spreading centers of plate-tectonic activity form seafloor massive sulfide (SMS) deposits. Given that the SMS deposits found in the western Pacific have been considered to be potential sources of gold (Au), silver (Ag), cupper (Cu), zinc (Zn), and lead (Pb) including manganese nodules and cobalt-rich manganese crusts, there is a strong possibility that they will be mined in near future. In order to take measures against environmental impact during the mining of SMS deposits, it is important to measure components of hydrothermal origin with high temporal and spatial resolution on site, and to understand the ecosystem in the hydrothermal environment. In this study, we first propose a measurement method of turbidity profiles using an Acoustic Doppler Current Profiler (ADCP). Applying this method to the ADCP measurements in the Izena Calderon with SMS in the Okinawa Trough, we verify that this method can extract turbidity data from echo intensities measured by ADCP. Subsequently, we describe the high-turbidity water in the Izena Calderon measured by ADCP, and present and discuss the turbidity fluctuations estimated by applying time-frequency analysis to these turbidity data.
Ultimate Capacity Behavior of Pitted Mild Steel Plates Under Biaxial Compression
Authors: Jiang Xiaoli , Guedes Soares C.
Published: November 2011

The aim of the present paper is to investigate the effects of corrosion pits on the ultimate capacity of rectangular mild steel plates under biaxial compression. A series of non-linear FEM analysis on plates with partial depth pits are carried out, changing geometrical attributes of both pits and plates, i.e., the radius, depth, location and distribution of the pits and the slenderness of the plates. Possible interaction between transverse and longitudinal axial compression is studied applying different level of loading ratio and considering the effects of partial depth pitting corrosion. It is shown that biaxial loading ratio is a dominant factor affecting the behavior of pitted plates besides pits intensity and thickness loss at pits. When longitudinal compression is dominant load with loading ratio lower than 1, the interaction relationship curves for different DOP levels tend to be parallel with each other and the distance between every two parallel curves seems to be dependent mainly on the deviation of their DOP values and thickness loss at pits. Moreover, pits distribution along long and shirt edges could also affect the ultimate strength behavior of plates. The work done in the paper illustrates that the ultimate capacity of pitted plate could be derived from intact plate by introducing important influential parameters like DOP, thickness loss and possible pits distribution.
The Empirical Mode Decomposition Applied to Dynamic Positioning Systems
Authors: Morishita Helio Mitio , Kubota Leonardo , Vestri Michaelli Sforsin , Greuell Solenn , Moratelli La´zaro
Published: November 2011

Dynamic Positioning Systems installed in marine vessels require a filtering block to attenuate the wave frequency components captured by the position and heading sensors. In this paper a filtering algorithm based on the Empirical Mode Decomposition (EMD) is suggested. The EMD is an algorithm that claims to properly identify the time scales featuring the physical characteristics of any given system by analyzing a time series representative of the system dynamics. It can handle both non stationary and non linear signals and it requires no previous knowledge on the system dynamics. Details of the algorithm are provided and the results obtained from simulation and experimental tests are presented.
Numerical Tower Shadow Modeling for a Downwind Wind Turbine Truss Tower
Authors: Hagen Torbjo̸rn Ruud , Reiso Marit , Muskulus Michael
Published: November 2011

The numerical simulation of offshore wind turbines needs a realistic tower shadow model, especially when studying downwind wind turbine designs. Using computational fluid dynamic simulations of the wind flow field around a two-dimensional tubular tower and corresponding truss tower cross-sections we show that current tower shadow models do not correctly represent the mean wind speeds close to such complex geometries. Interestingly, the multi-member extension of Powles’ tower shadow model with the square-root law is found to be adequate for the truss tower at moderate distances, and we suggest parameter values that better reproduce the velocities encountered by the blades in such circumstances. Finally, velocity spectra show that the fluctuations behind the two towers are almost an order of magnitude smaller for the truss tower. This suggests that downwind wind turbines on truss towers might suffer less from fatigue damage than downwind machines on tubular towers.
VIV Prediction of a Truss Spar Pull-Tube Array Using CFD
Authors: Constantinides Yiannis , Yu Weiwei , Holmes Samuel
Published: November 2011

Complex flows through cylinder arrays, such as the case of pull-tubes located in the truss section of a truss spar, are very difficult to describe and analyze. It is especially difficult to predict and correct Vortex Induced Vibration (VIV) response using traditional tools that were developed to analyze single cylinder rather than arrays of cylinders. Computational Fluid Dynamics (CFD) offers the designer the ability to properly analyze these complex problems and increase the reliability of his design. In this study, a full scale truss spar with pull-tubes is modeled using CFD coupled with an FEA structural model of the pull-tubes for a fluid-structure interaction (FSI) computation. The VIV response of the pull-tubes is predicted and analyzed for different current headings and speeds.
Vortex-Induced Vibration Analysis (VIVA) Based on Hydrodynamic Databases
Authors: Zheng Haining , Price Rachel , Modarres-Sadeghi Yahya , Triantafyllou George S. , Triantafyllou Michael S.
Published: November 2011

We outline the procedures used by program VIVA, developed over the last sixteen years to estimate the cross-flow vibration of marine risers in arbitrary currents. The program theory is based on a combination of first principles, extensive hydrodynamic databases, as well as modifications introduced through comparison against experimental and field data. The program was built from the start to handle standing as well as traveling waves, or arbitrary combinations of traveling and standing waves, through the use of complex modes. Considerable effort was expended to develop a hydrodynamic methodology that is suitable for short and long risers and cables, and which provides results in agreement with recent observed mechanisms. In particular, we outline changes to take into account: • the influence of in-line as well as cross-flow oscillations; • the influence of the Reynolds number; • the effect of high force harmonics; • modeling of lock-in in a sheared flow; • modeling of staked sections. The methodology is illustrated through several examples where predictions are compared with field and experimental data.
Zap-Lok® Connection Testing and Axial Strength Design
Authors: Vargas Pedro , Crowder Ben , Roberts David
Published: November 2011

Zap-Lok® is a pipe joining technology which relies on radial-interference elastic strain and surface friction to join pipes. The connection consists of a “bell” (expanded end) into which a “pin” (the straight end of the adjoining pipe) is forcefully inserted to provide an interference fit (See Figure 1). Joining is accomplished via a specialized hydraulic joining press provided by Zap-Lok® which grips both pipe sections and forces them together. A thin layer of the patented epoxy is applied internally to the bell end, and externally to the pin end, to provide lubrication for the insertion. The joining operation takes approximately ten seconds. Both the bell and the pin are formed to specified tolerances per specification by Zap-Lok® technicians, and may be done in the field or shop. Typical applications include gathering and distribution systems, transmission lines and specialized pipe installations on land and offshore. Of particular interest is the ability to withstand corrosive products with the application of an internal coating that does not sustain damage during the joining operation. To qualify this technology for use extensive testing and analyses was performed. We found that: • In sour service applications the plastic deformation of the bell necessitated a heat treatment to insure that the connection remained NACE compliant. • The axial strength capacity was found to be somewhat less than that of a welded joint. • Burst capacity of the joint was robust. • The joint did not leak even after several cycles of significant plasticity. • Fatigue performance of the joint rivaled that of a lower-end girth weld (i.e. F2 S-N curve). A design method was developed to correctly account for the axial strength using basic ASME-type design concepts. In this presentation we summarize the connection mechanics, testing results, analytical models and design method for the Zap-Lok® connection.
Tank Model Testing of a Fish-Cage Flotation/Submersion System Using Flexible Hoses
Authors: Kitazawa Daisuke , Mizukami Yoichi , Isobe Masaaki , Kinoshita Hiromi , Hirayama Mamoru , Ikeda Satoshi , Takeuchi Yoto
Published: November 2011

A fish-cage flotation/submersion system using flexible hoses is proposed to achieve horizontally stable floating and sinking motions. Waterproof flexible hoses are inserted into polyethylene pipes installed at the top of the frame of the fish cage. These hoses flatten when they are devoid of air and water as the fish cage is submerged. The injection of high-pressure air regenerates buoyancy and enables the fish cage to rise in the water. The advantage of this system is the uniform, circumferential generation of buoyancy at the top of the frame, which suppresses inclination of the fish cage and concomitant deformation of the flexible chemical fiber nets. Tank model testing was carried out to examine the inclination and the floating velocity of the fish cage. Tauchi’s similarity law was applied to make a 1/30 model of the full-scale fish cage. The tank model of the fish cage was installed in the ocean engineering basin at the University of Tokyo, and it was made to float and sink in water with and without currents. The inclination and position of the fish cage were measured using video camera images. As a result, the proposed fish cage was observed to float stably in still water in contrast to systems based on the existing method. When subjected to water currents, the new fish cage inclined by a maximum of 18° just after leaving the bottom; the inclination was reduced with further ascension. The ratio of buoyancy to gravity, the rate of air injection, and the arrangement of the flexible hoses should be optimized to achieve a more stable motion. The floating velocity for the rising fish cage in still water was then analyzed. The drag coefficient of the fish cage, as calculated from experimental data, corresponded to that estimated from a structural analysis of the fish cage. Analysis projected accelerated motion for 0.02 s after the fish cage rose from the bottom, while acceleration lasted a few seconds in the tank model test. This is because uniformly accelerated motion was assumed in the analysis, while the acceleration actually varies from zero to a constant acceleration, because of the difference between gravity and the varying buoyancy of the flexible hoses.
Review of Fuzzy Set Theory Applications in Safety Assessment for Marine and Offshore Industries
Authors: Mentes Ayhan , Helvacioglu Ismail H.
Published: November 2011

Various safety analysis techniques have been generated in dealing with uncertain information over the past three decades. The safety assessment based on conventional risk methods may not be well suited with most problems possessing high level of contingencies in marine and offshore systems. In other words, the effect of less confidence, unreliable, missing or incomplete data in safety assessment is arduous to apply common safety and risk assessment techniques for maritime industry. Therefore, fuzzy logic based approaches are probably more appropriate to apply in carrying out safety assessment for maritime systems. This paper presents a survey of applications in fuzzy set theory for safety analysis to marine and offshore industries’ problems. The safety assessment methods are presented in detail by demonstrating their robust and weak points. Subsequently, the main results on the application of fuzzy set theory for safety assessment will be further explained. Finally, recommendations in undertaking developments into the field of maritime safety assessment will be given.
Functional Data Analysis and Wave Profiles During a Storm
Authors: Ortega Joaqui´n , Gorrostieta Cristina , Smith George H.
Published: November 2011

Functional Data Analysis is a set of statistical tools developed to perform statistical analysis on data having a functional form. In our case we consider the one-dimensional wave profiles registered during a North-Sea storm as functional data. The waves are defined as the surface height between two consecutive downcrossings. Data is split into 20-minute periods and after registration of the waves to the interval [0,1], the mean wave is obtained along with the first two derivatives of this mean profile. We analyze the shape of these mean waves and their derivatives and show how they change as a function of the significant wave height for the corresponding time interval. We also look at the evolution of the energy, as represented by the phase diagram, as a function of significant wave height. The results show the asymmetry in vertical and horizontal scales for real data. To consider how the individual waves vary we perform a Functional Principal Component Analysis of wave profiles, dividing previously the waves into groups according to their height and comparing with waves measured during a non-storm period. The results suggest that the modes of variation of wave profiles do not depend on wave height or sea condition.
Density multiplication of nanostructures fabricated by ultralow voltage electron beam lithography using PMMA as positive- and negative-tone resist
Authors: Adeyenuwo Adegboyega P. , Stepanova Maria , Dew Steven K.
Published: November 2011

The authors report a density multiplication process for nanoscale patterns composed of dots and lines using electron beam lithography with low voltage 1 keV exposures and cold development. The density doubling is achieved in a single exposure-development step using polymethylmethacrylate (PMMA) as the resist. PMMA exhibits a dual positive- and negative-tone behavior depending on the electron dose employed in this density multiplication process. Fabricated nanostructures are characterized via scanning electron microscopy and subsequent feature size measurements. After density doubling, the minimum dot diameter of an initially 80 nm pitch array of single pixel dots was measured as approximately 27 nm, and the minimum width in an initially 100 nm pitch array of lines was approximately 21 nm. Methodologies for controlling the dimensions of fabricated structures are discussed. Modeling of the electron beam exposure has been carried out using an original electron beam lithography simulator in order to understand the nominal yields of scission in PMMA required in order to achieve the density multiplication, and the results are discussed.
Neurointensive care biophysiological monitoring: Table 1
Authors: Dhawan Vikram , DeGeorgia Michael
Published: November 2011

Monitoring various physiological parameters and their derangements provides a valuable tool for management of severely brain injured patients. The various parameters and their monitoring tools include but are not all inclusive are cerebral blood flow and oxygen monitoring, jugular bulb oximetry, intracerebral microdialysis and continuous electroencephalography. It needs to be seen how these devices are applied to improve patient outcomes.
The relationships between microbiological attributes and soil and litter quality in pure and mixed stands of native tree species in southeastern Bahia, Brazil
Authors: Gama-Rodrigues Emanuela F. , Gama-Rodrigues Antonio Carlos , Barros Nairam F. , Moço Maria Kellen S.
Published: November 2011

This study was conducted to link soil and litter microbial biomass and activity with soil and litter quality in the surface layer for different pure and mixed stands of native tree species in southeastern Bahia, Brazil. The purpose of the study was to see how strongly the differences among species and stands affect the microbiological attributes of the soil and to identify how microbial processes can be influenced by soil and litter quality. Soil and litter samples were collected from six pure and mixed stands of six hardwood species ( Peltogyne angustifolia , Centrolobium robustum , Arapatiella psilophylla , Sclerolobium chrysophyllum , Cordia trichotoma , Macrolobium latifolium ) native to the southeastern region of Bahia, Brazil. In plantations of native tree species in humid tropical regions, the immobilization efficiency of C and N by soil microbial biomass was strongly related to the chemical quality of the litter and to the organic matter quality of the soil. According to the variables analyzed, the mixed stand was similar to the natural forest and dissimilar to the pure stands. Litter microbial biomass represented a greater sink of C and N than soil microbial biomass and is an important contributor of resources to tropical soils having low C and N availability.
On the life cycle of Hymenolepis evaginata Barker and Andrews, 1915 (Cestoda: Cyclophyllidea), a parasite of muskrats, Ondatra zibethica (L., 1766)
Authors: Greaves T. A. , Jarecka L. , Burt M. D. B.
Published: November 2011

Between October 2, 1985, and November 16, 1986, 129 muskrats, Ondatra zibethica were collected in New Brunswick and examined for parasites. Forty-one of the muskrats harboured the the cestode Hymenolepis evaginata in the small intestine, with infections ranging from 1-10 worms per host. To determine the intermediate host of H. evaginata, a number of aquatic and terrestrial invertebrates were exposed to oncospheres in the laboratory. Full development of a tailed cysticercoid only occurred in the ostracod Cyclocypris laevis. The cysticercoid undergoes typical protocepyhalic development in this micro-crustacean. This characteristic, regarded as primitive, occurs in hymenolepidids found in aquatic birds. It appears that although this cestode is commonly found in mammals, it is more closely related to aquatic avian hymenolepidids than to those found in terrestrial mammals.
PLANNING RELOCATION OF PEOPLE FOR DEVELOPING SURFACE MINES IN DENSELY POPULATED AREAS: OPTIMIZATION OF MULTIPLE OBJECTIVES
Authors: ZAHIR SAJJAD , SARKER RUHUL
Published: November 2011

Surface mining, often adopted for exploiting natural resources all over the world, is a major subject of debate as it causes major environmental impacts. It not only adversely alters the landscape but it also seriously hampers the traditional living conditions of numerous inhabitants, who may be displaced against their wishes without receiving necessary compensation. In this paper, goal programming is combined with the analytic hierarchy process to determine optimal decisions for the planned relocation of people where surface mining may take place in a densely populated environment, while addressing multiple conflicting objectives. The combined approach is illustrated with a numerical example highlighting its usage in other decision problems.
A GALERKIN MESHFREE METHOD WITH STABILIZED CONFORMING NODAL INTEGRATION FOR GEOMETRICALLY NONLINEAR ANALYSIS OF SHEAR DEFORMABLE PLATES
Authors: WANG DONGDONG , SUN YUE
Published: November 2011

A Galerkin meshfree approach formulated within the framework of stabilized conforming nodal integration (SCNI) is presented for geometrically nonlinear analysis of large deflection shear deformable plates. This method is based upon a Lagrangian curvature smoothing in which the smoothed curvature is constructed within a nodal representative domain on the initial configuration. It is shown that the Lagrangian smoothed nodal gradients of the meshfree shape function is capable of exactly representing arbitrary constant curvature fields in the discrete sense of nodal integration. The consistent linearization is performed on the weak form of large deflection plate in the context of the total Lagrangian description. Subsequently, the discrete incremental equations are obtained by the method of SCNI in which to relieve the locking as well as ensure the stability of the present scheme, the bending contribution is evaluated using the smoothed nodal gradients, while the membrane and shear contributions are computed with the direct nodal gradients. The effectiveness of the present method is thoroughly demonstrated through several numerical examples.
EXPERIMENTAL POOL BOILING HEAT TRANSFER STUDY OF THE NANOPOROUS COATING IN VARIOUS FLUIDS
Authors: KWARK SANG M. , AMAYA MIGUEL , YOU SEUNG M.
Published: November 2011

An experimental pool boiling study was conducted using plain and nanoporous coated heater surfaces immersed in various working fluids: water, ethanol and HFE-7100. Pool boiling tests were performed on flat 1 cm × 1 cm heaters. Unlike in water, the critical heat flux (CHF) enhancement of the nanoporous coating seems to be less or marginal in ethanol and HFE-7100 at 1 atm. The reduced effect of the nanoporous coating in ethanol and HFE-7100 is believed to be due to the highly wetting nature of these fluids since no obvious difference in wettability is observed between nanoporous coated and uncoated surfaces through apparent contact angle measurement. Moreover, pressure effects were also investigated for the fluids mentioned above. For the nanoporous coated surface, CHF enhancement of the nanoporous coating appeared to be dependent on the test pressure, showing greater CHF enhancement at lower pressure. It is believed that this pressure dependent CHF enhancement behavior could be closely related to the bubble departure diameter. As pressure lowers, the departure bubble size increases and this allows the nanoporous coating to become more influential, even for the highly wetting fluids, in delaying local dry-out, which in turn results in increasing CHF enhancement.
Creep Behavior of Passive Bovine Extraocular Muscle
Authors: Yoo Lawrence , Kim Hansang , Shin Andrew , Gupta Vijay , Demer Joseph L.
Published: November 2011

This paper characterized bovine extraocular muscles (EOMs) using creep, which represents long‐term stretching induced by a constant force. After preliminary optimization of testing conditions, 20 fresh EOM samples were subjected to four different loading rates of 1.67, 3.33, 8.33, and 16.67%/s, after which creep was observed for 1,500 s. A published quasilinear viscoelastic (QLV) relaxation function was transformed to a creep function that was compared with data. Repeatable creep was observed for each loading rate and was similar among all six anatomical EOMs. The mean creep coefficient after 1,500 seconds for a wide range of initial loading rates was at 1.37 ± 0.03 (standard deviation, SD). The creep function derived from the relaxation‐based QLV model agreed with observed creep to within 2.7% following 16.67%/s ramp loading. Measured creep agrees closely with a derived QLV model of EOM relaxation, validating a previous QLV model for characterization of EOM biomechanics.
On the Localization of the Riesz Means of Multiple Fourier Series of Distributions
Authors: Rakhimov A. A.
Published: November 2011

We study special partial sums of multiple Fourier series of distributions. We obtain sufficient conditions of summation of Riesz means of Fourier expansions of distributions with compact support.
The Microcantilever: A Versatile Tool for Measuring the Rheological Properties of Complex Fluids
Authors: Dufour I. , Maali A. , Amarouchene Y. , Ayela C. , Caillard B. , Darwiche A. , Guirardel M. , Kellay H. , Lemaire E. , Mathieu F. , Pellet C. , Saya D. , Youssry M. , Nicu L. , Colin A.
Published: November 2011

Silicon microcantilevers can be used to measure the rheological properties of complex fluids. In this paper, two different methods will be presented. In the first method, the microcantilever is used to measure the hydrodynamic force exerted by a confined fluid on a sphere that is attached to the microcantilever. In the second method, the measurement of the microcantilever's dynamic spectrum is used to extract the hydrodynamic force exerted by the surrounding fluid on the microcantilever. The originality of the proposed methods lies in the fact that not only may the viscosity of the fluid be measured, but also the fluid's viscoelasticity, that is, both viscous and elastic properties, which are key parameters in the case of complex fluids. In both methods, the use of analytical equations permits the fluid's complex shear modulus to be extracted and expressed as a function of shear stress and/or frequency.
Immunohistological analysis of extracted anterior cruciate ligament graft impinged against posterior cruciate ligament
Authors: Kato So , Fukai Atsushi , Takeda Hideki , Taketomi Shuji , Nakayama Shuichi , Hirota Jinso , Nakajima Kohei , Nakamura Kozo , Nakagawa Takumi
Published: November 2011

A young female athlete suffered from the residual instability of the knee after anterior cruciate ligament (ACL) reconstruction with hamstring autograft. The 3-dimensional (3-D) CT scan showed the "high noon" positioning of the primary femoral bone tunnel. The revision surgery with anatomic double-bundle technique was performed two years after the primary surgery and the femoral tunnels were created with the assistance of the 3-D fluoroscopy-based navigation. An arthroscopic examination confirmed the ACL graft impingement against posterior cruciate ligament (PCL) when the knee was deeply flexed. The histological analysis of the resected primary ACL graft showed local inflammatory infiltration, enhanced synovial coverage and vascularization at the impinged site. The enhanced expression of vascular endothelial growth factor (VEGF) at the impinged area when compared with non-impinged area was observed on immunohistochemical analysis. Abnormal mechanical stress by the impingement against PCL might have induced chronic inflammation and VEGF overexpression.
In VivoPathogenic Role of Mutant SOD1 Localized in the Mitochondrial Intermembrane Space
Authors: Igoudjil Anissa , Magrané Jordi , Fischer Lindsey R. , Kim Hyun Jeong , Hervias Isabel , Dumont Magali , Cortez Czrina , Glass Jonathan D. , Starkov Anatoly A. , Manfredi Giovanni
Published: November 2011

Mutations in Cu,Zn superoxide dismutase (SOD1) are associated with familial amyotrophic lateral sclerosis (ALS). Mutant SOD1 causes a complex array of pathological events, through toxic gain of function mechanisms, leading to selective motor neuron degeneration. Mitochondrial dysfunction is among the well established toxic effects of mutant SOD1, but its mechanisms are just starting to be elucidated. A portion of mutant SOD1 is localized in mitochondria, where it accumulates mostly on the outer membrane and inside the intermembrane space (IMS). Evidence in cultured cells suggests that mutant SOD1 in the IMS causes mitochondrial dysfunction and compromises cell viability. Therefore, to test its pathogenic rolein vivowe generated transgenic mice expressing G93A mutant or wild-type (WT) human SOD1 targeted selectively to the mitochondrial IMS (mito-SOD1). We show that mito-SOD1 is correctly localized in the IMS, where it oligomerizes and acquires enzymatic activity. Mito-G93ASOD1 mice, but not mito-WTSOD1 mice, develop a progressive disease characterized by body weight loss, muscle weakness, brain atrophy, and motor impairment, which is more severe in females. These symptoms are associated with reduced spinal motor neuron counts and impaired mitochondrial bioenergetics, characterized by decreased cytochrome oxidase activity and defective calcium handling. However, there is no evidence of muscle denervation, a cardinal pathological feature of ALS. Together, our findings indicate that mutant SOD1 in the mitochondrial IMS causes mitochondrial dysfunction and neurodegeneration, butper seit is not sufficient to cause a full-fledged ALS phenotype, which requires the participation of mutant SOD1 localized in other cellular compartments.
Azolylborates for Electrochemical Double Layer Capacitor Electrolytes
Authors: Francke Robert , Cericola D. , Kötz R. , Waldvogel Siegfried R.
Published: November 2011

Asymmetric tetraalkylammonium salts of azolylborates were synthesized and studied with respect to their suitability as supporting electrolytes in electrochemical double layer capacitors. In contrast to current conducting salts used in this device, azolylborates exhibit an excellent stability towards thermal load and moisture. In addition to good conductivity and stability towards cathodic reduction we found certain limitations when more positive potentials were applied.
Desempenho agronômico da cultura do girassol em diferentes condições edafoclimáticas do Sudeste paranaense
Authors: Ribeiro Maria de Fátima dos Santos , Daros Edelclaiton , Caires Eduardo Fávero , Vasconcellos Maria Elisabeth da Costa
Published: November 2011

O objetivo do presente trabalho foi quantificar as faixas de rendimentos acessíveis em diferentes condições edafoclimáticas do Sudeste paranaense e hierarquizar os fatores relacionados à variabilidade dos rendimentos observados. Foram avaliadas 26 situações culturais em 13 estabelecimentos familiares, em 2007 e 2008. As variáveis de componente do rendimento e estado nutricional da cultura foram determinadas pela coleta de dados em campo, e as variáveis de estado hídrico foram estimadas com o uso de um modelo de simulação do balanço hídrico. Estas foram analisadas pela Análise de Componentes Principais, classificando-se, posteriormente, as observações pela Análise de Agrupamento. Foram utilizadas as cultivares BRS 122, CATISSOL e Helio 250. Foram grupados os valores de rendimento de aquênios em três classes, segundo os seguintes valores médios: rendimentos altos: 1995 kg ha-1; rendimentos médios: 1359 kg ha-1; rendimentos baixos: 961 kg ha-1. Os valores de rendimento de óleo também foram agrupados nas seguintes classes, segundo os seguintes valores médios: rendimentos altos: 927 kg ha-1; rendimentos médios: 543 kg ha-1; rendimentos baixos: 423 kg ha-1. A variabilidade dos rendimentos (aquênios e óleo) foi explicada pela variabilidade no número de aquênios por capítulo. Em 2008, a variabilidade no número de aquênios por capítulo esteve correlacionada à deficiência hídrica em R1-R4 e R4-R6 e aos teores de Ca, B e P no tecido foliar. Ocorreu inibição competitiva entre K e Mg, porém este fenômeno não esteve correlacionado à variabilidade do número de aquênios por capítulo. Ocorreu estresse hídrico durante o enchimento de aquênios, porém este não explicou a variabilidade no rendimento de aquênios e de óleo.