bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion-Fatigue Performance of High-Strength Riser Steels in Seawater and Sour Brine Environments
Authors: Hudak Stephen J. , Robledo Guadalupe B. , Hawk Jeffrey
Published: November 2011

Although new high-strength steels have recently been developed to meet the demands of increased reservoir pressures, and sour production fluids, the corrosion-fatigue performance of these new higher-strength materials is largely unknown. The goal of this study was to fill this knowledge gap by generating corrosion-fatigue data in two aggressive environments: 1) a sour production brine, and 2) seawater with cathodic protection. The focus of the current paper is on stress-life (S-N) corrosion-fatigue results in these environments, as well as a baseline air environment. Experiments were performed on five different steels with yield strengths ranging from 848 MPa to 1080 MPa. Prior frequency-scan results based on corrosion-fatigue crack growth rate data demonstrated that not all of these material-environment combinations exhibit a saturation frequency where the detrimental environmental effect approached a constant value as the cyclic loading frequency is decreased. Consequently, S-N tests were performed at different frequencies (0.01 Hz, 0.17 Hz, and 1 Hz), depending on the fatigue life regime, in attempting to match the loading frequencies experienced in service. Corrosion-fatigue occurred at stresses well below the fatigue endurance limit in laboratory air, and cyclic lives in the seawater with cathodic protection environment were found to be 2X to 10X less than those in the baseline air environment, while cyclic lives in the sour brine environment were found to be 30X to 100X less than those in the baseline air environment. In both environments, degradation was greatest at lower stresses in the high cycle fatigue regime. The effect of material strength level had little or no measurable effect on the S-N corrosion-fatigue performance, and the effect of cyclic frequency on the corrosion-fatigue performance was mixed. The S-N response to these two variables differed significantly from recently measured fatigue crack growth kinetics in these same materials that were performed in a companion study. Possible reasons for these differences are discussed.
Flow Induced Rotation of a Flat Plate Subjected in Uniform Current Based on the Streamline Theory
Authors: Sefat Sina Mirzaei , Fernandes Antonio Carlos
Published: November 2011

This work describes the behavior of a vertical flat plate free to rotate in uniform current. The intention of this research is to study the fluttering problem that may occur with falling objects in water such as a manifold during the pendulous installation method (PIM). The free streamline theory is applied here to investigate the steady, two-dimensional flow at a given angle of attack past a flat plate with a fully developed wake. The leading and trailing edges of the plate are assumed to be sharp and the flow configurations are such that the free streamlines separate from the plate at these sharp edges, the thickness of the flat plate is assumed to be of zero. The Roshko’s model will be used to approximate the wake far downstream. The moment coefficient formulation has been calculated for different angles of attack yielding good accuracy with experimental results. This includes the existence of a natural frequency for small amplitude oscillations. The free-streamline theory confirms that the natural frequency is linearly proportional to the incoming flow velocity.
ECA for Operation: Is Today’s Practice of Relying on SENB Instead of SENT Testing While Not Taking Internal Pressure Into Account Conservative?
Authors: Olso̸ Erlend , Heier Espen , Nyhus Ba˚rd , O̸stby Erling
Published: November 2011

Today’s analytical equations that are the basis for most engineering critical assessments (ECA) are not currently able to account for the effect of internal pressure, and the industry does not have a common recognized procedure for assessing the integrity of pipelines for longitudinal strains in the plastic range during operation. An industry practice has therefore developed where more conservative SENB specimens are used to compensate for the current lack of ability of analytical equations to account for the effect of biaxial stress of in-service pipelines. This paper investigates whether current practice of using fracture mechanics data from SENB testing while ignoring internal pressure during operation is conservative, or whether non-conservative assessments may be the result.
Optimization of Corrugated Shell Plating for Marine Structures
Authors: Ringsberg Jonas W. , Sag˘lam Hu¨seyin , Sarder Md. Asaduzzaman , Ulfvarson Anders
Published: November 2011

The structural weight of a shell-plated structure can be reduced in numerous ways. The current investigation presents an example of innovative lightweight design of the pontoon of an offshore platform by utilization of corrugated structure. The corrugated shell plating is compared with a conventional stiffened panel with respect to strength, weight and cost. For this purpose, an optimization methodology is developed for shell-plated marine structures. The procedure enables the analysis/comparison of various (structural) solutions with regard to strength characteristics, weight and cost. Here, strength characteristics include ultimate tensile strength, buckling stability and fatigue life analyses. Linear elastic finite element analyses are carried out to generate input to the structural characteristics studies, which involve several design criteria according to classification rules. The results show that in competition with the traditional stiffened panel, the corrugated shell-plated structure can be used as the more lightweight design solution. It can be manufactured and installed at a lower cost. Finally, the structural strength characteristics analyses show that, when designed properly, classification rules are fulfilled without compromising with the safety margins.
Experimental Study of Slow-Drift Ship Motions in Shallow Water Random Waves
Authors: Stansberg Carl Trygve , Kristiansen Trygve
Published: November 2011

Slowly varying motions and drift forces of a large moored ship in random waves at 35m water depth are investigated by an experimental wave basin study in scale 1:50. A simple horizontal mooring set-up is used. A second-order wave correction is applied to minimize “parasitic” long waves. The effect on the ship motion from the correction is clearly seen, although less in random wave spectra than in pure bi-chromatic waves. Empirical quadratic transfer functions (QTFs) of the surge drift force are found by use of cross-bi-spectral analysis, in two different spectra have been obtained. The QTF levels increase significantly with lower wave frequencies (except at the diagonal), which is special for finite and shallow water. Furthermore, the QTF levels frequencies at low frequencies increase significantly out from the QTF diagonal. Thus Newman’s approximation should preferrably not be used in these cases. Using the LF waves as a direct excitation in a “linear” ship force analysis gives random records that compare reasonably well with those from the cross-bi-spectral analysis. This confirms the idea that the drift forces in shallow water are closely correlated to the second-order potential, and thereby by the second-order LF waves.
A Level 3 BS7910 ECA for a Titanium Stress Joint for Use on a High Motion Floater in the Gulf of Mexico
Authors: Vargas Pedro , Baxter Carl , Schutz Ronald
Published: November 2011

Titanium is increasingly being applied to offshore installations due to its high strength, low modulus, environmental resistant properties and high fatigue capacity. These combined properties make certain titanium alloys ideal in the application as a stress joint (TSJ) where flexibility and fatigue capacity are the main design limitations. Over 80 TSJs are currently in service worldwide and are now being designed for more arduous fatigue service involving high motion floaters and locations with more severe sea states. This paper explores the application of BS7910 level 2 & 3 ECA for an ASTM Grade 29 titanium production riser TSJ to a 100 year storm operational limit, and a 1000 year storm survival event for a high motion floater in the GOM. Two critical locations are addressed: 1) A section at the top of the tapered wall immediately below where the TSJ terminates at the platform in the stress joint and where the base material properties apply, and 2) the girth weld location farther down the tapered section where the wall is thinner. Typical measured J-R curves together with Paris-law constants with mean stress effects incorporated are presented and used in the ECA. Comparisons between the BS7910 level 2 and 3 show the increase in allowable defects due to the more elaborate procedure at level 3. However, since the fatigue loading (and S-N endurance) of this particular case is high, the allowable initial defects turn out to be small for the weld location, and the weld location was more critical than the base metal location in spite of lower fatigue loading. This is due to the weld metal having a higher crack growth rate in the Paris region, a reduced crack growth threshold, and a reduced J-R curve. Other approaches to fatigue performance integrity for cases where allowable defects may be too small to detect are suggested. These include the local thickening of the wall at the weld and the redesign of the taper profile optimized for fatigue rather than extreme load only. It is concluded that: a) Level 3 analysis gives larger allowable initial defects level 2; b) It is important to carry out ECA at an early stage in the design process to identify potential problem areas; c) Non-conventional NDE methods should be investigated for future TSJs which are designed to operate under demanding fatigue loadings.
Motion Reduction for Spar Platform With Hydro-Pneumatic Tensioners
Authors: Bian Xiaoqiang Sean , Spillane Michael W. , Rijken Oriol R.
Published: November 2011

The Spar platform is one of the options to support dry-trees from a floating unit, particularly in increasing water depth. The recent Spar developments in Gulf of Mexico (GOM) favor Spar Supported Hydro-pneumatic Tensioners to support Top Tensioned Vertical Risers (TTR). The trend has been made possible by, as well as promoted the long-stroke RAM type hydro-pneumatic tensioner market. Currently up to 35 ft stroke tensioners are technically available and 28 ft ones are installed and field tested on GOM spars. The primary advantage, compared with buoyancy cans, is its possible integrated installation. Aside from taking payload from the hull, hydro-pneumatic tensioners have stiffness and can effectively reduce the heave period closer to the dominant wave period. It’s imperative to control the resonance motion, particularly of a classic spar which is generally low damped in heave. This study investigates the heave reduction by using an air-spring-water-column Vibration Absorber (VAB) mounted vertically inside the spar, the vibration absorbers consist of vertical caissons, open at the bottom to the sea and closed at the top. Each caisson consists of a water column providing mass (unsupported by the Spar) and a dual-chamber air spring, which interacts with the Spar. The motion of the water column produces pressure variations out-of-phase with the resonant motions of the Spar, resulting in reduced heave. Damping of the vibration absorber is provided by an orifice connecting the two air chambers, and is used to allow effective operation across varying frequencies. The detailed background of VAB and the application can be found in references [1] and [4]. This paper describes a classic spar platform with its heave motion reduced by using VAB to the point that market available hydro-pneumatic tensioners can be used. The theory of the Vibration Absorber and the procedure of configurating the system are introduced in this paper. The platform, mooring system and global motion analysis of the proposed facility are described for GOM applications with performance comparable to an existing truss Spar platform. Both frequency domain and time domain analysis of the coupled motions are included in this study.
Three Dimensional LES Simulation of Bi-Directional Turbine for Wave Energy Conversion
Authors: Velez Carlos , Papesh Brent , Ilie Marcel , Qu Zhihua
Published: November 2011

Development of technology to harness the vast amount of renewable energy available in nature has been ever-increasing in popularity. A worldwide desire to limit dependency on fossil fuels as a means to produce power has motivated research in solar, wind, and wave energies, as well as other clean, naturally-abundant energy sources. This research details an innovative design for a wave energy harvester that converts the heaving motion of waves into electrical power. The conceptual design utilizes a unique bidirectional turbine system that develops torque in a single direction, independent of whether the fluid is moving upward or downward. The result is power production both as the buoy is heaved upward by a wave as well as while the buoy falls after the wave passes. A transient three dimensional LES turbulent CFD model of the bi-directional turbine system is modeled in OpenFoam. A dynamic boundary is introduced in order to model the transitional period in which water flow changes direction within the bi-directional turbine channel. The analysis of the simulation will conclude in an optimized load control algorithm which can adapt the generator load to increase the systems efficiency during the flow transitional period.
Empirical Procedures for Long-Term Prediction of Fatigue Damage for an Instrumented Marine Riser
Authors: Shi C. , Manuel L. , Tognarelli M. A.
Published: November 2011

Slender marine risers used in deepwater applications can experience vortex-induced vibration (VIV). It is becoming increasingly common for field monitoring campaigns to be undertaken wherein data loggers such as strain sensors and/or accelerometers are installed on such risers to aid in VIV-related fatigue damage estimation. Such damage estimation relies on the application of empirical procedures that make use of the collected data. This type of damage estimation can be undertaken for different current profiles encountered. The empirical techniques employed make direct use of the measurements and key components in the analyses (such as participating riser modes selected for use in damage estimation) are intrinsically dependent on the actual current profiles. Fatigue damage predicted in this manner is in contrast to analytical approaches that rely on simplifying assumptions on both the flow conditions and the response characteristics. Empirical fatigue damage estimates conditional on current profile type can account explicitly even for complex response characteristics, participating riser modes, etc. With significant amounts of data, it is possible to establish “short-term” fatigue damage rate distributions conditional on current type. If the relative frequency of different current types is known from metocean studies, the short-term fatigue distributions can be combined with the current distributions to yield integrated “long-term” fatigue damage rate distributions. Such a study is carried out using data from the Norwegian Deepwater Programme (NDP) model riser subject to several sheared and uniform current profiles and with assumed probabilities for different current conditions. From this study, we seek to demonstrate the effectiveness of empirical techniques utilized in combination with field measurements to predict long-term fatigue damage and life.
The Span Mitigation Analysis With Use of Advanced FEA Modeling Techniques
Authors: Wang James , Banneyake Ranil , Huang Shawn , Jukes Paul , Eltaher Ayman
Published: November 2011

Spans occur when a pipeline is laid on a rough undulating seabed or when upheaval buckling occurs due to constrained thermal expansion. This not only results in static and dynamic loads on the flowline at the span section, but also generates vortex induce vibration (VIV) which can lead a fatigue issue. The phenomenon, if not predicted and control properly, will result in significant damage to the pipeline integrity, leading to expensive remediation and intervention works. There are various span mitigation methods in use for both over stressing and fatigue concerns. The mitigation methods, if not analyzed properly, may result in much unnecessary work or generate more problems or concerns in the future. The mitigation analysis can become very challenging due to many restrictions in the field such as the minimum and maximum heights or lift of mechanical supports or grout bags, and bearing capacity vs. cost of supports. The cost of different mitigation methods and their interactions are the other considerations along with the installation tolerances, challenges associated with the water depth and uncertainties in seabed properties. This paper describes the latest developments in use of finite element analysis to investigate associate mitigation solutions given the governing practical limitations and cost factors. The ULS and fatigue lift criteria are used as the guidelines. The methods presented within this paper are applicable for various span conditions. Conclusions are then drawn to the impact of these various scenarios so that the pipeline integrity can be assured with confidence.
The Investigation of Non-Linear Effect for a Circular Cylinder Shaped FPSO
Authors: Hong Sam-Kwon , Yuck Rae-Hyoung , Jang Beom-Seon , Kang Hi-Seok , Kim Se-Eun , Seo Jong-Soo
Published: November 2011

Nowadays, a circular cylinder shaped FPSO appears as a new type FPSO because it does not need the expensive turret system. A circular cylinder shaped FPSO has an excellent motion performance because pitch and roll natural periods are longer compared to traditional FPSO and heave natural period is also longer due to its small water plane area. Samsung heavy industries has developed a circular cylinder shaped FPSO called as S-Line. The feature of S-line has a shape cutting a groove around draft to reduce the water plane area. Through reducing water plane area, the heave natural frequency moves to lower frequency which is far from ocean waves. According to the results of a linear calculation by WAMIT, S-Line showed reduced vertical motion of heave, roll and pitch compared to conventional FPSO. But, S-Line showed unsuspected large pitch response in 1st model test which was carried out with horizontal mooring system by spring in SSMB (Samsung Ship Model Basin). It is conjectured that this large pitch response is caused by 2nd nonlinearity of the wave and/or parametric pitch phenomena. To verify the mooring load and improve the 2nd order pitch motion, model tests were carried out in SSMB and offshore basin of MOERI (Maritime & Ocean Engineering Research Institute) with two kinds of bilge box. This paper describes the nonlinear effect of 2nd order for pitch motion of a circular cylinder shaped FPSO based on model test and numerical simulation. As a result, S-Line developed by Samsung was also verified being able to use SCR (Steel Catenary Riser) due to its improved heave motion performance.
Estimators of Wave Peak Period for Large Return Period Seastates
Authors: Drago Michele , Ciuffardi Tiziana , Giovanetti Giancarlo
Published: November 2011

Different functional relationships for the distribution of the peak period Tp for a given seastate Hs are tested against hindcasted and measured time series for various locations in the European seas, namely Barents Sea, Baltic Sea and Western Mediterranean (Tyrrhenian) Sea. The aim is to investigate their performance when extrapolating from available data for the estimation of the long return period seastates which are not covered by the length of the time series. A second complementary objective of the paper is to quantify the uncertainty and the variability that can occur in the estimation of the Hs/Tp association when a short time series is available. This is done by assessing the Hs/Tp relation from a 35-years long time series that will be considered as the correct one. Then it will be compared with those obtained by analysing multiple cases of shorter and shorter portions of the time series. The spread of the results against the one obtained with the entire time series will be estimated to give some indications about how long a time series has to be to ensure a correct extrapolation to the long return period seastates and to provide an indication of the error that can affect the results when a short time series is available.
Characterizing Metal Arc Welding Under Oil (MAW-UO)
Authors: Almostaneer Hamad H. , Liu Stephen , Olson David L.
Published: November 2011

Metal arc welding under oil (MAW-UO) is a new, revolutionary process for the repair of pipelines without the need of hot tapping and constructing bypass lines. The process uses an automated metal arc welding setup with a continuous wire feed. This process was developed for in-situ internal repairs of in-service cross-country pipelines, tanks and vessels by using a smart-pig with a modified mechanical design that allows for welding. Since some of the cross-country pipeline segments are either buried or under highways making access difficult, the new process will provide great flexibility to the repair of these pipelines. In this paper, the development of the MAW-UO process is described. Process parameters that successfully produced weldments are identified and the consumables tested are reported and discussed. The unique characteristics found in the under oil welds will be discussed in detail and related to the processing parameters and the oil environment. Welding is possible under oil because of the vaporization of the oil to form an oil vapor bubble that surrounds the welding arc plasma and protects the molten steel weld pool. Contrary to general belief, oil does not combust in the presence of a welding arc. The low oxygen content within the oil itself and the low diffusivity of oxygen within the oil even at elevated temperatures are the two main factors that prevent oil combustion during welding. Decomposition of the oil and the decomposed products are expected to significantly affect the weld metal composition and microstructure.
RANS Simulation vs. Experiments of Flow Induced Motion of Circular Cylinder With Passive Turbulence Control at 35,000<Re<130,000
Authors: Wu Wei , Bernitsas Michael M. , Maki Kevin
Published: November 2011

Two-dimensional RANS equations with the Spalart-Allmaras turbulence model are used to simulate the flow and body kinematics of a rigid circular cylinder mounted on springs, transversely to a steady uniform flow in the high-lift, TrSL3 regime with 35,000<Re<130,000. Passive Turbulence Control (PTC) in the form of selectively distributed surface roughness is used to alter the cylinder Flow Induced Motion (FIM). Simulation is performed by using a solver based on the open source CFD tool OpenFOAM, which solves continuum mechanics problems with a finite volume discretization method. Roughness parameters of PTC are simulated modeling tests conducted in the Marine Renewable Energy Lab (MRELab) of the University of Michigan. The numerical tool is first tested on smooth cylinder in VIV and results are compared with available experimental measurements and RANS simulations. For the cylinder with PTC cases, the sandpaper grit (k) on the cylinder wall is modeled as a rough-wall boundary condition. Two sets of cases with different system parameters (spring constant, damping) are simulated and the results are compared with experimental data measured in the MRELab. The amplitude-ratio curve shows clearly three different branches, including the VIV initial and upper branches and a galloping branch, similar to those observed experimentally. Frequency ratio, vortex patterns, transitional behavior, and lift are also predicted well for PTC cylinders at such high Reynolds numbers.
ALDH2 Activator Inhibits Increased Myocardial Infarction Injury by Nitroglycerin Tolerance
Authors: Sun Lihan , Ferreira Julio Cesar Batista , Mochly-Rosen Daria
Published: November 2011

Tolerance to nitroglycerin, a drug often used to treat chest pain, increases susceptibility to injury by myocardial infarction.
Basic life support skill retention of medical interns and the effect of clinical experience of cardiopulmonary resuscitation
Authors: Na Ji Ung , Sim Min Seob , Jo Ik Joon , Song Hyoung Gon , Song Keun Jeong
Published: November 2011

Objective

To investigate the level of basic life support (BLS) skill retention of medical interns 6 and 12 months after BLS education and analyse the correlation between clinical experience of cardiopulmonary resuscitation (CPR) and BLS skill retention.

Materials and methods

The baseline performance of BLS skills in medical doctors during their internship was tested immediately after the BLS provider course. The subjects were divided into two groups, which were tested using the same method after 6 months or after 12 months. Data on the subjects' CPR experience were collected through CPR records—specifically, the number of CPR experiences and the feedback given by the CPR team leaders. To evaluate BLS skill retention, baseline BLS skill performance was compared with the skill performances measured after 6 or 12 months.

Results

Fifty-six subjects were enrolled in the 6 month group and 36 in the 12 month group. For non-compression skills, the points for skills declined from 12 to 6 points in the 6 month group and from 12 to 6 points in the 12 month group and the declines in both groups were statistically significant. For compression skills, in the 12 month group, the hands-off time improved from 9.9 s to 8.7 s, with statistical significance. In the multivariate linear regression test, the number of times feedback was given had a statistical relationship with improvement in hands-off time in the 12 month group (coefficient 0.58, 95% CI 0.12 to 1.05).

Conclusions

In medical doctors, the compression skills were well preserved, but the retention of non-compression skills was poor.
Assessing where vulnerable groups fare worst: a global multilevel analysis on the impact of welfare regimes on disability across different socioeconomic groups
Authors: Witvliet Margot I , Kunst Anton E , Stronks Karien , Arah Onyebuchi A
Published: November 2011

Background

Investigations on health differences within welfare states between low- and high-socioeconomic groups are mainly conducted in Europe. With the aim of gaining global insight on the extent welfare regimes influence personal disability for the most vulnerable, we explore how these health differences vary between low- and high-socioeconomic groups.

Methods

The World Health Survey data were analysed on 199 595 adults from 46 countries using the welfare regime classification developed by Wood and Gough. Multilevel logistic regression was used to estimate welfare regime differences in self-reported disability according to individual educational attainment and employment status.

Results

As compared with the low educated in the European-conservative regime, the odds of having a higher prevalence of disability was found among low-educated people residing in the informal-security regime of South Asia, with OR being 3.16 (95% CI 2.23 to 4.47). While state-organised regimes seemed to offer more protection against disability to the low educated, the productivist regime of East Asia trailed closely behind, with OR being 1.10 (95% CI 0.76 to 1.60) for the low educated. Similar findings were also observed in the unemployed.

Conclusions

State-organised regimes of Europe and the productivist regime of East Asia seem to contain protecting features against disability for all citizens and especially for the most vulnerable. Apart from the productivist regime of East Asia, the low educated and the unemployed seem to carry the greatest health burden within more insecure regimes, highlighting a deficiency in social provisions within these regimes aimed at protecting the most vulnerable.
The importance of CD4 count, viral load and highly active antiretroviral therapy in HIV-associated thrombotic thrombocytopenic purpura (TTP): Figure 1
Authors: Hill Quentin A , Minton Jane
Published: November 2011

A case is reported of HIV-associated thrombotic thrombocytopenic purpura with normal CD4 count but high HIV viral load, developing neurological and cardiac complications up to 36 days after initiation of plasma exchange, but remitting within 18 days of the start of highly active antiretroviral therapy and steroids. In addition to plasma exchange, prompt initiation of highly active antiretroviral therapy in patients with HIV-associated thrombotic thrombocytopenic purpura may be justified despite a normal CD4 count.
Survival of extremely and moderately halophilic isolates of Tunisian solar salterns after UV-B or oxidative stress
Authors: Trigui Hana , Masmoudi Salma , Brochier-Armanet Céline , Maalej Sami , Dukan Sam
Published: November 2011

Adaptation to a solar saltern environment requires mechanisms providing tolerance not only to salinity but also to UV radiation (UVR) and to reactive oxygen species (ROS). We cultivated prokaryote halophiles from two different salinity ponds: the concentrator M1 pond (240 g·L–1NaCl) and the crystallizer TS pond (380 g·L–1NaCl). We then estimated UV-B and hydrogen peroxide resistance according to the optimal salt concentration for growth of the isolates. We observed a higher biodiversity of bacterial isolates in M1 than in TS. All strains isolated from TS appeared to be extremely halophilic Archaea from the genus Halorubrum . Culturable strains isolated from M1 included extremely halophilic Archaea (genera Haloferax , Halobacterium , Haloterrigena , and Halorubrum) and moderately halophilic Bacteria (genera Halovibrio and Salicola ). We also found that archaeal strains were more resistant than bacterial strains to exposure to ROS and UV-B. All organisms tested were more resistant to UV-B exposure at the optimum NaCl concentration for their growth, which is not always the case for H2O2. Finally, if these results are extended to other prokaryotes present in a solar saltern, we could speculate that UVR has greater impact than ROS on the control of prokaryote biodiversity in a solar saltern.
Determination of low bacterial concentrations in hyperarid Atacama soils: comparison of biochemical and microscopy methods with real-time quantitative PCR
Authors: Fletcher Lauren E. , Conley Catharine A. , Valdivia-Silva Julio E. , Perez-Montaño Saul , Condori-Apaza Renee , Kovacs Gregory T.A. , Glavin Daniel P. , McKay Christopher P.
Published: November 2011

Hyperarid Atacama soils are reported to contain significantly reduced numbers of microbes per gram of soil relative to soils from other environments. Molecular methods have been used to evaluate microbial populations in hyperarid Atacama soils; however, conflicting results across the various studies, possibly caused by this low number of microorganisms and consequent biomass, suggest that knowledge of expected DNA concentrations in these soils becomes important to interpreting data from any method regarding microbial concentrations and diversity. In this paper we compare the number of bacteria per gram of Atacama Desert soils determined by real-time quantitative polymerase chain reaction with the number of bacteria estimated by the standard methods of phospholipids fatty acid analysis, adenine composition (determined by liquid chromatography – time-of-flight mass spectrometry), and SYBR-green microscopy. The number determined by real-time quantitative polymerase chain reaction as implemented in this study was several orders of magnitude lower than that determined by the other three methods and probably underestimates the concentrations of soil bacteria, most likely because of soil binding during the DNA extraction methods. However, the other methods very possibly overestimate the bacteria concentrations owing to desiccated, intact organisms, which would stain positive in microscopy and preserve both adenine and phospholipid fatty acid for the other methods.
EFFECT OF NANO PARTICLE SIZES ON HIGH PRESSURE RAMAN SCATTERING IN NANOCRYSTALLINE CERIUM DIOXIDE
Authors: JIMLIM P. , BOVORNRATANARAKS T. , CHAIMAYO W. , PRATONTEP S.
Published: November 2011

Nanocrystalline CeO 2 with different particle sizes has been studied under high pressure using Raman spectroscopy techniques and diamond anvil cell at room temperature. The pressure shift of the first-order Raman frequency for each particle sizes was measured. Linear dependence of the first order Raman frequency on pressure for each particle sizes has been observed. We found that the first order Raman frequency decreases with the decreasing particle sizes under ambient condition and the lattice constant increases with the decreasing particle size. The increasing molar fraction of oxygen vacancies with the decreasing particle size is responsible for the lattice expansion.
STRONG FLUX PINNING OF NANO-SIZED YSZ PARTICLES IN YBCO FILMS PREPARED BY MOD METHOD
Authors: YE S. , SUO H. L. , LIU M. , TANG X. , WU Z. P. , ZHAO Y. , ZHOU M. L.
Published: November 2011

The YBCO films with doped YSZ nanoparticles have been prepared successfully by metal organic doepositon method using trifluoroacetates (TFA-MOD) through dissolving Zr organic salt into the YBCO precursor solution. The doped films have well in-plane and out-plane textures detected by both XRD Φ-scan and ω-scan. The YSZ nanoparticles with the size of about 5 ~ 15 nm were observed on the surface of the YBCO films using both FE-SEM and TEM. By comparing the superconducting properties, it was found that the doped YBCO films had lower Tc than that of undoped YBCO films. However, as increasing the applied magnetic field, Jc of the doped YBCO films were much better than that of undoped one. The Jc was as higher as 2.5 times than that of undoped YBCO film at 77 K and 1 T applied field.
NONLINEAR THIN-WALLED BEAMS WITH A RECTANGULAR CROSS-SECTION — PART I
Authors: FREDDI LORENZO , MORA MARIA GIOVANNA , PARONI ROBERTO
Published: November 2011

Our aim is to rigorously derive a hierarchy of one-dimensional models for thin-walled beams with rectangular cross-section, starting from three-dimensional nonlinear elasticity. The different limit models are distinguished by the different scaling of the elastic energy and of the ratio between the sides of the cross-section. In this paper we report the first part of our results. More precisely, denoting by h and δh the length of the sides of the cross-section, with δh ≪ h, and by [Formula: see text] the scaling factor of the bulk elastic energy, we analyze the cases in which δh/εh → 0 (subcritical) and δh/εh → 1 (critical).
A MULTISCALE APPROACH TO CELL MIGRATION IN TISSUE NETWORKS
Authors: KELKEL JAN , SURULESCU CHRISTINA
Published: November 2011

We derive a multiscale model for tumor cell migration allowing to account for the receptor-mediated movement of the cells, the degradation of tissue fibers and the subsequent production of a soluble ligand whose concentration gradient then acts together with the distribution of tissue fibers as a directional cue for the cells. For this model we present a result on the local existence and uniqueness of a solution in all biologically relevant space dimensions.
LEADING ORDER ASYMPTOTICS OF STATIONARY NAVIER–STOKES FLOWS IN THE PRESENCE OF A WALL
Authors: GUO ZHENGGUANG , WITTWER PETER , ZHOU YONG
Published: November 2011

We consider the problem of a body moving within an incompressible fluid at constant speed parallel to a wall, in an otherwise unbounded domain. We give a detailed description of the asymptotic behavior on the fluid flow in a half-space using as a starting point the theory of existence of solutions which is obtained by interpreting the coordinate perpendicular to the wall as time variable.
COMPUTATIONAL METHODS AND MODELS NEEDED FOR SUSTAINABILITY RESEARCH BASED ON A CARBON-DIOXIDE BALANCE THEORY
Authors: LIU G. R.
Published: November 2011

This short article introduces first a Carbon-dioxide Balance Theory for sustainability of creatures living in the Earth atmosphere. A brief discussion then is presented on the importance of such a theory in policy making. An appeal is issued to all IJCM readers and author for making more efforts in creating computational methods and models to deal with sustainability issues.
DYNAMIC LOAD IDENTIFICATION FOR UNCERTAIN STRUCTURES BASED ON INTERVAL ANALYSIS AND REGULARIZATION METHOD
Authors: LIU J. , HAN X. , JIANG C. , NING H. M. , BAI Y. C.
Published: November 2011

In this paper, an inverse method that combines the interval analysis with regularization is presented to stably identify the bounds of dynamic load acting on the uncertain structures. The uncertain parameters of the structure are treated as intervals and hence only their bounds are needed. Using the first-order Taylor expansion, the identified load can be approximated as a linear function of the uncertain parameters. In this function, it is assumed that the load at the midpoint of the uncertain parameters can be expressed as a series of impulse kernels. The finite element method (FEM) is used to obtain the response function of the impulse kernel and the response to the midpoint load is expressed in a form of convolution. In order to deal with the ill-posedness arising from the deconvolution, two regularization methods are adopted to provide the numerically efficient and stable solution of the desired unknown midpoint load. Then, a sensitivity analysis is suggested to calculate the first derivative of the identified load with respect to each uncertain parameter. Applying the interval extension in interval mathematics, the lower and upper bounds of identified load caused by the uncertainty can be finally determined. Numerical simulation demonstrates that the present method is effective and robust to stably determine the range of the load on the uncertain structures from the noisy measured response in time domain.
DESIGN OF ASYMMETRIC GEAR AND ACCURATE BENDING STRESS ANALYSIS USING THE ES-PIM WITH TRIANGULAR MESH
Authors: WANG S. , LIU G. R. , ZHANG G. Y. , CHEN L.
Published: November 2011

This paper proposes a novel design of an asymmetric gear that applies a larger pressure angle in the drive side and a standard pressure angle in the coast side via accurate stress analysis using the edge-based smoothed point interpolation method with triangular mesh (ES-PIM-(T3)). An asymmetric rack cutter is first developed. Then, the governing equations of the tooth profiles cut by the rack cutter are derived. Finally, five sets of asymmetric gears with the pressure angles of 20° /20°, 25°/20°, 30°/20°, 35°/20°, and 40°/20° are established to quantitatively check the stress distributions at the fillet of the drive side of these teeth. The best point for applying force in a static bending stress analysis and the best pressure angle in the drive side for a gear design are suggested.
NODAL INTEGRATION THIN PLATE FORMULATION USING LINEAR INTERPOLATION AND TRIANGULAR CELLS
Authors: CUI X. Y. , LIN S. , LI G. Y.
Published: November 2011

This paper presents a thin plate formulation with nodal integration for bending analysis using three-node triangular cells and linear interpolation functions. The formulation was based on the classic thin plate theory, in which only deflection field was required and dealt with as the field variables. They were assumed to be piecewisely linear and expressed using a set of three-node triangular cells. Based on each node, the integration domain has been further derived, where the curvature in the domain was computed using a gradient smoothing technique (GST). As a result, the curvature in each integration domain is a constant whereby the deflection is compatible in the whole problem domain. The generalized smoothed Galerkin weak form is then used to create the discretized system equations where the system stiffness is obtained using simple summation operation. The essential rotational boundary conditions are imposed in the process of constructing the curvature field in conjunction with imposing the translational boundary conditions in the same way as undertaken in the standard FEM. A number of numerical examples were studied using the present formulation, including both static and free vibration analyses. The numerical results were compared with the reference ones together with those shown in the state-of-art literatures published. Very good accuracy has been achieved using the present method.
NUMERICAL SIMULATION ON TWO-PHASE BUBBLY FLOW SPLIT IN A BRANCHING T-JUNCTION
Authors: LIU Y. , LI W. Z.
Published: November 2011

In this paper, a steady three-dimensional two-fluid computational fluid dynamics predictive model is presented to simulate the dispersed bubbly flow split phenomenon in a T-junction with 50 mm diameter for all arms. The fluid is treated as a mixture and the fundamental mass, momentum and turbulent equations are solved to account for the flow parameters, where the turbulence is modeled by the standard k − ε model. Simulation results imply that the gas phase inclines to flow into the side arm even for small extraction rate conditions, because the pressure difference of the side arm to inlet is much larger than that of run arm to inlet. The analysis of velocity field reveals that it is the inertia difference between the two phases that leads to the phase split phenomenon. The effect of bubble diameter on flow split is also investigated and it is found that split efficiency is greatly influenced by it. The computed solutions are compared with experimental data and a good agreement is achieved.
ENHANCEMENT OF HEAT AND MASS TRANSFER IN SOLID GAS SORPTION SYSTEMS
Authors: KIPLAGAT J. K. , WANG R. Z. , LI T. X. , OLIVEIRA R. G.
Published: November 2011

Solid gas sorption systems driven by heat have gained much attention due to their energy conservation and environmental benefits. These sorption machines can be driven by waste heat or renewable energy source such as solar energy, and can utilize natural working fluids with no GWP and ODP, such as water, methanol, and ammonia. However, poor heat transfer process and slow diffusion rate of the refrigeration gas in the adsorber have been identified as the main drawbacks limiting the cooling density performance, and consequently, commercialization of sorption machines. This paper provides a review of techniques that have been applied to enhance heat and mass transfer in solid gas sorption systems. These techniques mainly include the use of materials with high thermal conductivity, consolidation of adsorbents, and the use of specially designed heat exchangers in the adsorbers. The effect of these methods on the coefficient of performance and the specific cooling power is also discussed.
WAYS OF NEXT GENERATION REFRIGERANTS AND HEAT PUMP/REFRIGERATION SYSTEMS
Authors: MIYARA AKIO , ONAKA YOJI , KOYAMA SHIGERU
Published: November 2011

Since measures of the global warming are becoming urgent issues, various technical innovations and social system reformations are being promoted. In the engineering fields of heating, refrigerating, and air-conditioning, the global warming caused by the refrigerants is a big problem that must be solved. At the present stage, however, there are no perfect solutions for next generation refrigerants and heat pump/refrigeration systems by which the global warming is successfully prevented. Therefore, we have to search possible ways to the next generation. In this paper, important four ways which are (1) natural refrigerants, (2) low GWP synthetic refrigerants, (3) refrigerant management, and (4) refrigerant mixtures are introduced. For the refrigerant mixture which are CO2 /DME and HFO-1234ze(E)/HFC-32, cycle simulations have been conducted under different operation modes. COP of the mixtures has a maximum at certain concentration and they are higher than those of conventional refrigerants. From a drop-in test of HFO-1234ze(E)/HFC-32, feasibility of the refrigerant mixture has been proved.
VENTILATION OF THE ARCHEOLOGICAL TOMBS OF THE VALLEY OF KINGS, LUXOR, EGYPT
Authors: KHALIL ESSAM E.
Published: November 2011

The cultural heritage left by the Egyptian pharaohs in the tombs of the Valley of the Kings represents some of the key elements of the Egyptian cultural wealth and standing monuments demonstrating the wealth and technology of the pharaohs. As the pharaohnic civilization is one of the oldest civilizations, the dedicated preservation of its remaining monuments and collections should be the focus of sincere international efforts. A major heritage of this civilization, i.e., the tombs of the Kings, is intact in the Valley of the Kings, Luxor, Egypt. These tombs were prepared to bury the Kings' mummies and artifacts for eternal life. Many of the wall paintings identifying the various ancient rituals and life style are in good conditions as the tombs were only recently opened to the public. However, tourists' activities in these tombs have resulted, in many instances, in the dramatic deterioration of wall paintings due in part to excessive humidity. The current indoor air flow conditions and air quality in the tombs are quite alarming; hence, appropriate measures should be taken to preserve the tombs and their contents. This dilemma invokes the need for a proper ventilation system that stabilizes the air conditioning as well as addresses comfort levels of visitors. Deterioration can be from lighting effects, high temperature and relative humidity. Pest infections, shock and vibration are also potential causes among pollution and visitors' traffic.
Valsartan, independently of AT1 receptor or PPARγ, suppresses LPS-induced macrophage activation and improves insulin resistance in cocultured adipocytes
Authors: Iwashita Misaki , Sakoda Hideyuki , Kushiyama Akifumi , Fujishiro Midori , Ohno Haruya , Nakatsu Yusuke , Fukushima Toshiaki , Kumamoto Sonoko , Tsuchiya Yoshihiro , Kikuchi Takako , Kurihara Hiroki , Akazawa Hiroshi , Komuro Issei , Kamata Hideaki , Nishimura Fusanori , Asano Tomoichiro
Published: November 2011

Macrophages are integrated into adipose tissues and interact with adipocytes in obese subjects, thereby exacerbating adipose insulin resistance. This study aimed to elucidate the molecular mechanism underlying the insulin-sensitizing effect of the angiotensin II receptor blocker (ARB) valsartan, as demonstrated in clinical studies. Insulin signaling, i.e., insulin receptor substrate-1 and Akt phosphorylations, in 3T3-L1 adipocytes was impaired markedly by treatment with tumor necrosis factor-α (TNFα) or in the culture medium of lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophages, and valsartan had no effects on these impairments. However, in contrast, when cocultured with RAW 264.7 cells using a transwell system, the LPS-induced insulin signaling impairment in 3T3-L1 adipocytes showed almost complete normalization with coaddition of valsartan. Furthermore, valsartan strongly suppressed LPS-induced productions of cytokines such as interleukin (IL)-1β, IL-6, and TNFα with nuclear factor-κB activation and c-Jun NH2-terminal kinase phosphorylation in RAW 264.7 and primary murine macrophages. Very interestingly, this effect of valsartan was also observed in THP-1 cells treated with angiotensin II type 1 (AT1) siRNA or a peroxisome proliferator-activated receptor-γ (PPARγ) antagonist as well as macrophages from AT1a receptor-knockout mice. We conclude that valsartan suppresses the inflammatory response of macrophages, albeit not via PPARγ or the AT1a receptor. This suppression appears to secondarily improve adipose insulin resistance.