bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida
Authors: Deng Xianbao , Bashandy Hany , Ainasoja Miia , Kontturi Juha , Pietiäinen Milla , Laitinen Roosa A. E. , Albert Victor A. , Valkonen Jari P. T. , Elomaa Paula , Teeri Teemu H.
Published: November 2013

Chalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4‐coumaroyl‐CoA and malonyl‐CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB‐type regulator GMYB10 in gerbera (Gerbera hybrida).

The tissue‐ and development‐specific expression patterns of three gerbera CHS genes were examined. Virus‐induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in gerbera inflorescences.

Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin‐pigmented vegetative tissues of gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis.

Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in gerbera petals is regulated post‐transcriptionally, at the level of either translation elongation or protein stability.
Correlations of seed traits with tofu texture in 48 soybean cultivars and breeding lines
Authors: Huang Mao , Kaletunc Gonul , St. Martin Steve , Feller Marcia , McHale Leah K.
Published: November 2013

Food‐grade soybeans [Glycine max (L.) Merr] used to produce tofu have specific seed composition, shape, size and colour requirements. Seed qualities, such as protein content, have been correlated with tofu texture. The objective of this study was to determine the relationships between textural qualities of tofu and seed characters, including shape, size, density, weight, protein content and oil content. Tofu was produced from the seed of 48 high‐protein or food‐grade soybean lines grown at two locations in 2010. Four tofu textural traits were assessed including work to failure, deformability, stiffness and hardness. Seed protein and oil content were significantly correlated with stiffness and hardness, and protein was additionally correlated with work to failure. Pearson's correlation coefficients ranged from 0.45 to 0.60 (adjusted P‐values < 0.002) for protein and −0.49 to −0.35 for oil (adjusted P‐values < 0.016). No significant correlations between tofu texture and seed volume or shape were detected. Seed protein content can be assessed for indirect selection for tofu firmness, whereas this study reveals no evidence that seed size affects tofu texture.
IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis
Authors: Son Jinyoung , Kim Misun , Jou Ilo , Park Kyoung Chan , Kang Hee Young
Published: November 2013

Inflammatory cytokines are closely related to pigmentary changes. In this study, the effects of IFN‐γ on melanogenesis were investigated. IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis in B16 melanoma cells and normal human melanocytes. MITF mRNA and protein expressions were significantly inhibited in response to IFN‐γ. IFN‐γ inhibited CREB binding to the MITF promoter but did not affect CREB phosphorylation. Instead, IFN‐γ inhibited the association of CBP and CREB through the increased association between CREB binding protein (CBP) and STAT1. These findings suggest that IFN‐γ inhibits both basal and α‐MSH‐induced melanogenesis by inhibiting MITF expression. The inhibitory action of IFN‐γ in α‐MSH‐induced melanogenesis is likely to be associated with the sequestration of CBP via the association between CBP and STAT1. These data suggest that IFN‐γ plays a role in controlling inflammation‐ or UV‐induced pigmentary changes.
Oral Glycopyrrolate for Refractory Pediatric and Adolescent Hyperhidrosis
Authors: Kumar Monique G. , Foreman Rebecca S. , Berk David R. , Bayliss Susan J.
Published: November 2013

Primary hyperhidrosis is a common disorder affecting children and adolescents, and it can have a significant negative psychosocial effect. Treatment for pediatric hyperhidrosis tends to be limited by low efficacy, low adherence, and poor tolerance. Oral glycopyrrolate is emerging as a potential second‐line treatment option, but experience with safety, efficacy, and dosing is especially limited in children. We present an institutional review of 12 children with severe, refractory hyperhidrosis treated with oral glycopyrrolate; 11 (92%) noted improvement and 9 (75%) would recommend oral glycopyrrolate to their friends. No significant side effects were noted. Our retrospective analysis suggests that oral glycopyrrolate is safe and effective in children with hyperhidrosis.
Why is Rose Bengal More Phototoxic to Fibroblasts In Vitro Than In Vivo?
Authors: Yao Min , Gu Chuan , Doyle Francis J. , Zhu Hong , Redmond Robert W. , Kochevar Irene E.
Published: November 2013

Photosensitized protein cross‐linking has been recently developed to seal wounds and strengthen tissue. Although the photosensitizing dye, Rose Bengal (RB), is phototoxic to cultured cells, cytotoxicity does not accompany RB‐photosensitized tissue repair in vivo. We investigated whether the environment surrounding cells in tissue or the high irradiances used for photo–cross‐linking inhibited RB phototoxicity. Fibroblasts (FB) grown within collagen gels to mimic a tissue environment and monolayer cultured FB were treated with RB (0.01–1 mm) and the high 532 nm laser irradiances used in vivo for tissue repair (0.10–0.50 W cm−2). Monolayer FB were substantially more sensitive to RB photosensitization: the LD50 was >200‐fold lower than that in collagen gels. Collagen gel protection was associated with increased Akt phosphorylation, a prosurvival pathway. RB phototoxicity in collagen gels was 25‐fold greater at low (0.030 W cm−2) that at high (0.50 W cm−2) irradiances. Oxygen depletion at high irradiance only partially accounted for the irradiance dependence of phototoxicity as replacing air with nitrogen only increased the LD50 by four‐fold in monolayers. These results indicate that the lack of RB phototoxicity during in vivo tissue repair results from upregulation of prosurvival pathways in tissue cells, oxygen depletion and irradiance‐dependent RB photochemistry.
Antibodies are involved in the protective immunity induced in mice by Schistosoma mansoni schistosomula tegument (Smteg) immunization
Authors: de Melo T. T. , de Sena I. C. , Araujo N. , Fonseca C. T.
Published: November 2013

The Schistosoma mansoni schistosomula tegument (Smteg) plays an important role in triggering the host immune response and mice immunization with Smteg formulated with Freund's adjuvant or alum + CpG induce partial protection against S. mansoni infection associated with an increased antibody production. In this study, we investigated the role of these antibodies in parasite killing both in vitro and in vivo. We demonstrated that these antibodies were able to bind to the surface of S. mansoni recently transformed schistosomula and that these antibodies significantly increase the percentage of schistosomula killed in vitro by complement activation. Passive transference of immune sera decreased the parasite burden and the number of eggs trapped in the organs of mice that received sera containing anti‐Smteg antibodies. These results demonstrate that antibodies specific to surface tegumental antigens are involved in parasite elimination in mice immunized with Smteg.
Effects of tannic acid on Haemonchus contortus larvae viability and immune responses of sheep white blood cells in vitro
Authors: Zhong R. Z. , Sun H. X. , Liu H. W. , Zhou D. W.
Published: November 2013

Direct inhibitory effects of tannic acid on Haemonchus contortus viability were studied in vitro using the larval migration inhibition (LMI) assay. Sheep white blood cells (WBC) were preincubated with 5 and 50 μg/mL tannic acid or not followed by whole H. contortus antigen (WHA). Cells were harvested at 24 h post‐incubation to test host immune responses. Concentrations of 50, 100, 500, 1000, 3000 and 5000 μg/mL tannic acid inhibited larvae migration by 19·8, 42·4, 46·3, 92·0, 93·7 and 100%, respectively, within 96 h post‐incubation (P < 0·001). The relative mRNA levels of interferon (IFN)‐γ, interleukin (IL)‐2, IL‐4 and IL‐10 were increased by WHA stimulation without tannic acid. However, the increased effects on IFN‐γ and IL‐2 were inhibited by tannic acid preincubation (P < 0·001), while the increases in IL‐4 and IL‐10 were greatly enhanced by tannic acid preincubation (P < 0·001). Changes in protein levels of all cytokines essentially paralleled the changes in their corresponding mRNA levels. In conclusion, tannic acid is directly harmful to larvae in a dose‐ and time‐dependent manner and modulates immune responses of sheep WBC stimulated by H. contortus antigen by inhibiting Th1 cytokines and increasing Th2 cytokine expression in vitro.
Comparative analysis of anthocyanin biosynthesis during fruit development in two Lycium species
Authors: Zeng Shaohua , Wu Min , Zou Caiyun , Liu Xiaomin , Shen Xiaofei , Hayward Alice , Liu Chunzhao , Wang Ying
Published: November 2013

Dietary consumption of functional foods enriched in anthocyanins benefit for human health by protection against far‐ranging human diseases. Delphinidin‐derived anthocyanins (valuable as blue pigments and antioxidants) are accumulated specifically in the fruits of Lycium ruthenicum but not in the fruits of Lycium barbarum, suggesting the differences of anthocyanin biosynthesis between the two species. In this study, anthocyanin profiling confirmed that anthocyanins were increasingly accumulated during fruit ripening in L. ruthenicum, and sharply increased at full expanded mature fruit, while no anthocyanin were detected at any stage of L. barbarum fruit development. Several genes involved in anthocyanin biosynthesis were characterized in L. ruthenicum and L. barbarum fruits. Expression profiling of these genes during fruit development showed a significant positive correlation between transcript abundance and anthocyanin accumulation in L. ruthenicum fruit. Meanwhile, transcripts in L. barbarum fruit were either undetectable or were downregulated during fruit ripening, before increasing slightly in the final stages of maturation. In addition, the ratio of LrF3′5H/LrF3′H transcription showed a gradual increase before 6 days after breaker (DAB) and a sharp enhancement at 10 DAB. Our results suggest that the expression patterns of both regulatory and structural genes and the transcriptional ratio of branch‐node structural genes F3′5′H/F3′H may determine the phenotypic difference in anthocyanin biosynthesis between L. ruthenicum and L. barbarum fruits.
Nebulization of corticosteroids to asthmatic children: Large variation in dose inhaled
Authors: O'Callaghan Chris , White Judy A. , Kantar Ahmad
Published: November 2013

Background and objective

Despite problems associated with assessing the clinical effect and side effects of nebulized corticosteroids, little is known of the amount of drug that is inhaled by children with asthma or how this is affected by different drug formulations. The aim of this study was to test the hypothesis that children with asthma inhale the same proportion of the prescribed dose of nebulized fluticasone, beclomethasone dipropionate (BDP) and flunisolide.

Methods

The amount of nebulized drug that would have been inhaled by asthmatic children was captured on filters between the patient and nebulizer, and the amount contained in particles likely to reach the lung (i.e. <5 μm) is determined.

Results

The children studied would have inhaled 13% of the prescribed dose of fluticasone propionate, 21% of BDP and 25% of flunisolide. However, the percentage of the dose inhaled that was contained in particles <5 μm, and therefore more likely to reach the lungs, was only 5% of the prescribed dose of fluticasone propionate, 8% for BDP and 16% for flunisolide. The inter‐subject variation coefficient of the dose inhaled was much greater for suspensions of fluticasone propionate (34%) and BDP (45%) than for suspensions of flunisolide solution (9%).

Conclusions

Our results demonstrate that the prescribed dose may bear little resemblance to the dose delivered from a nebulizer and that the dose inhaled is significantly affected by the drug formulation prescribed.
Distributional Characteristics of Income Insecurity in the U.S., Germany, and Britain
Authors: Rohde Nicholas , Tang Kam Ki , Rao D.S. Prasada
Published: November 2013

This paper studies income volatility using recent data from the Cross National Equivalence File (CNEF). Measures of downward instability are applied to household income streams and the results are interpreted as indicators of income insecurity. Using this method we examine (i) cross national differences in average insecurity levels, (ii) the effects of taxes and transfers, and (iii) relationships between the insecurity index and household income. Insecurity estimates based on pre‐government incomes are highest in Britain and lowest in Germany, however results for post‐government incomes are highest in the U.S. It is also shown that insecurity estimates based upon pre‐government incomes are heavily concentrated at the lower end of the distribution; although governments are effective at smoothing the income streams of these households. We also search for determinants of our measure and find that gender, household size, health status, and industry affiliations of the household head are the most significant covariates.
Local Solutions to Inequality: Steps Toward Fostering a Progressive Social Movement
Authors: Bailey Conner
Published: November 2013

Over the past four decades, inequality of income, wealth, and power have become increasingly extreme in the United States. The triumph of a neoliberal agenda to reduce taxes, deregulate the economy, and promote international trade has undermined the economic status of the middle class, increased poverty, and led to a concentration of wealth. This nation has gone through such periods before, followed by progressive movements that have realigned economic and political forces. I argue that we may be at a point where a new progressive social movement is about to emerge and I point out several areas where rural sociologists are working, such as local food systems, that reflect a reorientation of social values supporting such a movement. Promoting local food systems and similar locality‐based enterprises can foster economic relationships embedded in multistranded social relationships and contribute to progressive change through reducing the central role of large corporations in our daily lives. Building on Busch's (1999) concept of Leviathan, I identify the roles of researchers and community activists in which rural sociologists can work to democratize social, economic, and political relationships in society.
Oral health status of people living with HIV/AIDS attending a specialized service in Brazil
Authors: Soares Gabriella Barreto , Garbin Cléa Adas Saliba , Moimaz Suzely Adas Saliba , Garbin Artênio José Ísper
Published: November 2013

Purpose

Verify factors that influence the oral health status of people living with HIV/AIDS (PLWHA) in Brazil.

Method and materials

The study was cross‐sectional and includes 177 HIV‐positive individuals, who answered questionnaire on the sociodemographic conditions, HIV aspects, habits, and satisfaction with the service. The oral health data were collected by means of the decayed, missing, and filled teeth (DMFT) index, use and need of dentures, and the Community Periodontal Index.

Results

Average number of the DMFT was 17.64. Most HIV‐positive patients presented good periodontal status, 35.0% used dentures, 41.5% needed denture in the maxilla, and 62.0% in the mandible. In the multivariate analysis, older age and dissatisfaction with health care were associated with nonuse of dentures. The abandonment of the use of antiretroviral therapy increased the risk of PLWHA presenting more than three decayed teeth.

Conclusion

Poor oral health of the PLWHA was mainly influenced by sociodemographic factors and use and satisfaction with service.
Three‐dimensional morphological characterization of the skin surface micro‐topography using a skin replica and changes with age
Authors: Masuda Y. , Oguri M. , Morinaga T. , Hirao T.
Published: November 2013

Background/purpose

Skin surface micro‐topography (SSMT), consisting of pores, ridges and furrows, reflects the skin condition and is an important factor determining the aesthetics of the skin. Most previous studies evaluating SSMT have employed two‐dimensional image analysis of magnified pictures captured by a video microscope. To improve the accuracy of SSMT analysis, we established a three‐dimensional (3D) analysis method for SSMT and developed various parameters including the skin ridge number, and applied the method to study the age‐dependent change in skin.

Methods

Confocal laser scanning microscopy was used for 3D measurement of the surface morphology of silicon replicas taken from the cheek. We then used these data to calculate the parameters that reflect the nature of SSTM including the skin ridge number using originally developed software. Employing a superscription technique, we investigated the variation in SSMT with age for replicas taken from the cheeks of 103 Japanese females (5–85 years old).

Results

The skin surface area and roughness, the area of pores, the area, length, depth and width of skin furrows and the number of skin ridges were examined. The surface roughness, the area of pores and the depth of skin furrows increased with age. The area and length of skin furrows and the number of skin ridges decreased with age.

Conclusion

The method proposed to analyse SSMT three dimensionally is an effective tool with which to characterize the condition of the skin.
Prototype tactile feedback system for examination by skin touch
Authors: Lee O. , Lee K. , Oh C. , Kim K. , Kim M.
Published: November 2013

Background/purpose

Diagnosis of conditions such as psoriasis and atopic dermatitis, in the case of induration, involves palpating the infected area via hands and then selecting a ratings score. However, the score is determined based on the tester's experience and standards, making it subjective. To provide tactile feedback on the skin, we developed a prototype tactile feedback system to simulate skin wrinkles with PHANToM OMNI.

Methods

To provide the user with tactile feedback on skin wrinkles, a visual and haptic Augmented Reality system was developed. First, a pair of stereo skin images obtained by a stereo camera generates a disparity map of skin wrinkles. Second, the generated disparity map is sent to an implemented tactile rendering algorithm that computes a reaction force according to the user's interaction with the skin image.

Results

We first obtained a stereo image of skin wrinkles from the in vivo stereo imaging system, which has a baseline of 50.8 μm, and obtained the disparity map with a graph cuts algorithm. The left image is displayed on the monitor to enable the user to recognize the location visually. The disparity map of the skin wrinkle image sends skin wrinkle information as a tactile response to the user through a haptic device.

Conclusion

We successfully developed a tactile feedback system for virtual skin wrinkle simulation by means of a commercialized haptic device that provides the user with a single point of contact to feel the surface roughness of a virtual skin sample.
Transforming the Miocene Altyn Tagh fault slip into shortening of the north‐western Qilian Shan: insights from the drainage basin geometry
Authors: Zhang Hui‐ping , Zhang Pei‐zhen , Zheng De‐Wen , Zheng Wen‐Jun , Chen Zheng‐Wei , Wang Wei‐Tao
Published: November 2013

Although it has long been proposed that active crustal shortening within the Qilian Shan accommodates slip along the Altyn Tagh fault, questions regarding the temporal and spatial amount of slip transfer remain debated. Traditional shortening calculations cannot yet be made accurately, because the geology is not known well enough. Following the view that long, linear drainage basins in the north‐western Qilian Shan developed in response to internal shortening associated with slip transfer along the Altyn Tagh fault, we targeted this special irregular drainage basin geometry to develop an alternative way to estimate shortening. We infer a total of ~66 km of shortening in the western Qilian Shan with a north‐eastward decrease in the magnitude of shortening. This ~39% shortening strain is comparable to previous estimates. Estimates of dates of initiation support the view that significant shortening and topographical growth within the north‐western Qilian Shan occurred in post‐Middle Miocene time.
Frequent isolation of Arthroderma benhamiae from dogs with dermatophytosis
Authors: Sieklucki Ursula , Oh Soon‐Hwan , Hoyer Lois L.
Published: November 2013

Background

Molecular analysis methods have led to many changes in the taxonomy of dermatophyte species.

Hypothesis/Objectives

We hypothesized that fungi displaying morphology consistent with a traditional identification of ‘Trichophyton mentagrophytes’ represent multiple species, consistent with the new taxonomy.

Methods

Fungal specimens (n = 20) were collected directly from animals with dermatophytosis, were among those submitted for diagnostic analysis or were part of historical teaching collections. Primers that amplified a portion of the 28S ribosomal RNA gene and primers specific for a fragment from the internal transcribed spacer region were used for PCR amplification of genomic DNA. The DNA sequences from the amplified products were compared with databases to identify the isolates.

Results

Of the 80% (n = 16) of the fungal isolates identified as Arthroderma benhamiae, eight were collected from dogs. One isolate was identified as Arthroderma vanbreuseghemii, two were Trichophyton erinacei and one was Nannizziopsis (Chrysosporium) guarroi, which was probably present as a saprophyte.

Conclusions and clinical importance

Frequent isolation of A. benhamiae from dogs suggests a greater host range for this fungus than reflected in the current literature. Our data also suggest the potential for geographical restriction of strain types within the species. Efforts to identify fungal isolates using molecular techniques create a better understanding of diversity and epidemiology of the dermatophytes.
Karrikins promote germination of physiologically dormant seeds of Chrysanthemoides monilifera ssp. monilifera (boneseed)
Authors: Reynolds C J , Long R L , Flematti G R , Cherry H , Turner S R
Published: November 2013

Physiological dormancy in weed species has significant implications for weed management, as viable seeds may persist in soil seedbanks for many years. The major stimulatory compound in smoke, karrikinolide (KAR1), promotes germination in a range of physiologically dormant weed species allowing targeted eradication methods to be employed. Control of Chrysanthemoides monilifera ssp. monilifera (boneseed), a Weed of National Significance in Australia, may benefit from adopting such an approach. In this study, we hypothesised that seeds of C. monilifera ssp. monilifera exhibit physiological dormancy, germinate more rapidly as dormancy is alleviated, show fluctuations in sensitivity to KAR1 and form a persistent soil seedbank. Seeds responded to 1 μM KAR1 (40–60% germination) even during months (i.e. March, April, July, August) when seeds were observed to be more deeply dormant (control germination: 7–20%). Seeds germinated readily over a range of cooler temperatures (i.e. 10, 15, 20, 20/10 and 25/15°C) and were responsive to KAR2 (~50% germination) as well. Eradication efforts for C. monilifera ssp. monilifera may benefit from use of karrikins to achieve synchronised germination from soil seedbanks, even at times of the year when C. monilifera ssp. monilifera seeds would be less likely to germinate, allowing more rapid depletion of the soil seedbank and targeted control of young plants.
On the Nusselt Number for H2 Heat Transfer in Rectangular Ducts of Large Aspect Ratios
Authors: Wang C. Y.
Published: November 2013

The H1 and H2 forced convection heat transfer in rectangular ducts are studied using an accurate, analytic method. It is confirmed that, as the aspect ratio tends to infinity, the Nusselt number for the H2 case approaches 2.9162, much lower than the parallel plate value of 8.2353 attained by the H1 case. The controversy about the H2 limit is thus settled. An explanation of the behavior is suggested.
Tension Loss of Hydro-Pneumatic Riser Tensioners
Authors: Li Songcheng , Campbell Mike , Howells Hugh , Orsak John
Published: November 2013

With drilling exploration extending to deeper water, the total top tension to lift a drilling riser increases accordingly. Tensioners with higher tension capacity are preferred to minimize the total number of tensioners due to space limitation on a drilling vessel. Higher tension capacity requires more advanced recoil control for emergency events. Hydro-pneumatic tensioners are widely used for risers with anti-recoil control in deep water, and are commonly simulated as an equivalent linear or nonlinear spring or a pneumatic system. The discrepancy between simulation and measurement calls for a model with rate dependent stiffness considering the compressibility of hydraulic oil, the interference of valve control and friction loss along piping or hose.

In this paper, the hydro-pneumatic tensioner system with anti-recoil valve control is simulated in 2HRecoil, a customized version of ANSYS Mechanical APDL, and benchmarked with commercial software DeepRiser. The tension loss due to hydraulic oil friction, mass inertia, piston-cylinder friction is evaluated with coupled riser motion. The conventional approach in simulating the hydro-pneumatic tensioner system as an equivalent pneumatic system is found inaccurate. The sensitivity of the pressure difference between the cylinder chamber and the high pressure accumulator on the gas constant is discussed. The scatter in predicting gas constant, friction and damping coefficients from measured data is explained using hydro-pneumatic approach.
Computational Modelling of Hydrogen Embrittlement in Weld Joints of Subsea Oil and Gas Components
Authors: Barrera Olga , Cocks Alan C. F.
Published: November 2013

The paper deals with the modelling of the combined hydrogen embrittlement phenomena: hydrogen enhanced local plasticity (HELP) and hydrogen induced decohesion (HID) in subsea dissimilar welds. Fractography analysis of dissimilar welds of 8630 steel / IN625 nickel alloy demonstrate that a cleavage-like fracture path is located through an area called the “featureless zone” characterized by the presence M7C3 carbides. This fracture morphology, which is noticed only in the presence of hydrogen, seems to be consistent with a hydrogen-induced decohesion (HID) mechanism along the M7C3 -matrix interface succeeded by a ductile-type fracture. In light of this the purpose here is to develop constitutive models of the “featureless zone”. We present two types of models: the former (i) is based on a classical continuum mechanics formalism; the latter (ii) is a mescoscopic type of model to represent more accurately the dislocation structure that develops in the vicinity of the carbide-particles. The model (i) describes some of the aspects involved in the failure process of a dissimilar AISI8630/IN625 weld, however continuum models are not appropriate for the scale of the carbide particles in the featureless region. The scale of the particles is such that the interaction of the particles with discrete dislocations and the dislocation structures generated around the particles play an important role in determining the constitutive response.
Selective Surface Roughness to Suppress Flow-Induced Motion of Two Circular Cylinders at 30,000<Re<120,000
Authors: Park Hongrae , Bernitsas Michael M. , Kim Eun Soo
Published: November 2013

In the Marine Renewable Energy Laboratory of the University of Michigan, selectively located surface roughness has been designed successfully to suppress vortex-induced vibrations of a single cylinder by 60% compared to a smooth cylinder. In this paper, suppression of flow-induced motions of two cylinders in tandem using surface roughness is studied experimentally by varying flow velocity and cylinder center-to-center spacing. The two identical cylinders are rigid, suspended by springs, and allowed to move transversely to the flow direction and their own axis. Surface roughness is applied in the form of four roughness strips helically placed around the cylinder. Results are compared to smooth cylinders also tested in this work. Amplitude ratio A/D, frequency ratio fosc/fn,water, and range of synchronization are measured. Regardless of the center-to-center cylinder distance, the amplitude response of the upstream smooth-cylinder is similar to that of the isolated smooth-cylinder. The wake from the upstream cylinder with roughness is narrower and longer and has significant influence on the amplitude of the downstream cylinder. The latter is reduced in the initial and upper branches while its range of VIV-synchronization is extended. In addition the amplitude of the upstream rough cylinder and its range of synchronization increase with respect to the isolated rough cylinder.
Shear Interaction and Transverse Buckling of Tensile Armours in Flexible Pipes
Authors: Sævik Svein , Li Henan
Published: November 2013

The present paper addresses aspects of stresses, relative sliding and buckling in tensile armour layers of flexible pipes. Analytical models for torsion and curvature due to both axisymmetric loads and bending are presented. A shear interaction model is further formulated that allows for including the effect of shear deformations in the plastic layers and the model performance is investigated with respect to two full-scale experiments. A simple analytical model for non constrained transverse tensile armour buckling is formulated and compared to laboratory test data. Numerical studies are carried out to investigate the validity range of the torsion and curvature both due to axisymmetric and bending loads. In the former case two different computer codes are applied together with results published by others to validate the model. In the latter case, models including friction interaction between layers and the effect of cyclic bending is used to investigate the performance of the analytical models.
Maneuvering Behavior of Ships in Irregular Waves
Authors: Skejic Renato , Faltinsen Odd M.
Published: November 2013

Ship maneuvering in waves is analyzed by using a unified seakeeping and maneuvering two-time scale model in irregular sea that has been applied by Skejic and Faltinsen [1] for regular waves. The irregular wave effects are accounted for by Newman’s [2] approximation of the slow-drift 2nd order wave loads valid for deep water (Faltinsen [3], Pinkster [29]).

The modular type maneuvering model (MMG model) based on Söding’s [4] nonlinear slender-body theory is used for the maneuvering analysis. Forces and moments due to rudder, propeller, and viscous cross-flow are accounted for as presented by Skejic and Faltinsen [1] and Yasukawa [5, 6]. In particular, the behavior of the propulsive coefficients (the thrust deduction and wake fraction) in waves (Faltinsen et al. [7], Faltinsen and Minsaas [8]) are discussed from the perspective of ship maneuvering characteristics in both regular and irregular wave environments.

The unified model of seakeeping and maneuvering for deep-water irregular waves is validated for the ‘S7-175’ (‘SR 108’) container ship in calm water and regular deep-water wave scenarios by comparison with experimental results by Yasukawa [5, 6]. The maneuvering model is applied to a ‘MARINER’ ship performing turning maneuver in irregular waves. The obtained results of the ships main maneuvering parameters are discussed from a statistical point of view.
Numerical Simulation of Wave Interaction With an Oscillating Wave Surge Converter
Authors: Rafiee Ashkan , Elsaesser Bjoern , Dias Frederic
Published: November 2013

This paper deals with numerical studies of wave interaction with an Oscillating Wave Surge Converters (OWSC) using a Godunov–type SPH method. The use of a Riemann solver in calculating the density field results in a smoother SPH pressure field. Hence, a more accurate estimation of loads on the OWSC is achieved. Furthermore, the Lagrangian form of the RANS k–ε model is included in the SPH equations to better capture the turbulent features of the flow. SPH simulations were performed in both two–dimensions (2D) and three–dimensions (3D) and results for the flow pattern and loads are compared with experimental data.
The Efficiency of Tidal Fences: A Brief Review and Further Discussion on the Effect of Wake Mixing
Authors: Nishino Takafumi , Willden Richard H. J.
Published: November 2013

Recent discoveries on the limiting efficiency of tidal fences are reviewed, followed by a new theoretical investigation into the effect of wake mixing on the efficiency of ‘full’ tidal fences (i.e. turbines arrayed regularly across an entire channel span). The new model is based on the momentum and energy balance equations but includes several unclosed terms, which depend on the actual (three-dimensional) characteristics of turbine near-wake mixing and therefore need to be modelled empirically. The new model agrees well with three-dimensional actuator disk simulations when those unclosed terms are assessed based on the simulations themselves, suggesting that this low-order model could serve as a basis to analyse how various physical factors (such as the design of turbines) affect the limiting efficiency of tidal fences via changes in those terms describing the characteristics of turbine near-wake mixing. Also discussed is the effect of wake mixing on the efficiency of ‘partial’ tidal fences.
Effect of Shut-Down Procedures on the Dynamic Responses of a Spar-Type Floating Wind Turbine
Authors: Jiang Zhiyu , Moan Torgeir , Gao Zhen , Karimirad Madjid
Published: November 2013

The design standards (IEC, DNV and GL) define a minimum set of combinations of external conditions and design situations as load cases. Like other design load conditions, the design situations relating to fault and shut-down events shall be addressed. Emergency shut down occurs in the presence of severe faults to prevent turbine damage. For pitch-regulated turbines, blade pitching to feather provides an effective means of aerodynamic braking. The blades are pitched to feather at the maximum pitch rate. This action exerts huge loading on the turbine and may challenge the structural safety. In this paper a 5-MW spar-type wind turbine is used as a case study. By using the HAWC2 code, the turbine pitch actuator fault and shut-down scenarios are simulated through external Dynamic Link Libraries. The shut-down scenarios are: normal shut down with blade pitching, emergency shut down with blade pitching, and emergency shut down with blade pitching and mechanical brake. Due to the occurrence of fault, the pitch angle of one blade is fixed from a specific occurrence time. The supervisory controller reacts by pitching the remaining two blades to the maximum pitch set. The maximum yaw motion value is observed after the first revolution of the rotor during which the tower-top torsion experiences a change of direction. Negative platform pitch motion as well as tower-bottom bending moment are induced due to the pitching activity of the two blades. The response extremes of the main shaft bending moment and the yaw motion exhibit clear variation with the blade azimuth when emergency shut down is initiated. The tower-bottom bending moment and nacelle acceleration are relatively more affected by the wave loads. For a given blade azimuth, larger response variation is observed under harsher environmental conditions. Under the fault scenario, the effects of different shut-down procedures on the response extremes are investigated. It is found that the response extremes are affected significantly by the rotor speed. Among the three procedures, normal shut down, which is associated with the slowest decaying aerodynamic excitations and the highest rotor speed, usually leads to the largest response extremes near the rated wind speed. The employment of mechanical brake reduces rotor speed, motion responses and structural responses effectively. During shut down, the responses of yaw motion, nacelle fore-aft acceleration, main shaft bending moment, and tower-bottom side-to-side moment may be of concern for the floating wind turbine studied.
Fatigue Crack Growth Rate and Fracture Toughness of API5L X65 in Sweet Environments
Authors: Tognarelli Michael A. , Thodla Ramgopal , Shademan Steven
Published: November 2013

Corrosion fatigue and fracture toughness in sour environments of APIX65 5L have typically been studied in relatively severe environments like NACE A and NACE B solutions. There are very limited data in sweet and mildly sour environments that are of interest in various applications. This paper presents fatigue crack growth frequency scans in a range of sweet and mildly sour environments as well as on different microstructures: Parent Pipe, Heat Affected Zone (HAZ) and Weld Center Line (WCL). The fatigue crack growth rate (FCGR) increased with decreasing frequency and reached a plateau value at low frequencies. FCGR in the sweet environments that were investigated did exhibit a frequency dependence (increasing with decreasing frequency) and had plateau FCGR in the range of 10–20× the in-air values. In the mildly sour environments that were investigated, FCGR was found to be about 25 to 30× higher than the in-air values. By comparison, in NACE A environments the FCGR is typically about 50× higher than the in-air values. The FCGRs of parent pipe and HAZ were found to be similar over a range of environments, whereas the WCL FCGR data were consistently lower by about a factor of 2×. The lower FCGR of the WCL is likely due to the lower concentration of diffusible hydrogen in the weld. FCGRs as a function of ΔK (stress integrity factor range) were measured on parent pipe at the plateau frequency. The measured Paris law curves were consistent with the frequency scan data.

Rising displacement fracture toughness tests were performed in a range of sweet and sour environments to determine the R-curve behavior. Tests were performed in-situ at a slow K-rate of 0.05Nmm−3/2/s over a range of environmental conditions on parent pipe. The initiation toughness and the slope of the R-curve decreased sharply in the sour environments. The initiation toughness and slopes were largely independent of the notch location as well as environmental conditions. Typical values of initiation toughness were in the range of 90–110N/mm.
Analysis of Added Resistance: Comparative Study on Different Methodologies
Authors: Seo Min-Guk , Lee Jae-Hoon , Park Dong-Min , Yang Kyung-Kyu , Kim Kyong-Hwan , Kim Yonghwan
Published: November 2013

This paper considers the comparative study on added resistance for different methodologies. An accurate prediction of added resistance and resultant power increase becomes an important issue in greenship design. There are several methodologies for the prediction of added resistance, and most of them are based on frequency domain approaches such as slender-body theory or wave Green-function approach. As the time-domain approaches becomes an alternative method for seakeeping analysis, the time-domain approaches are also applicable for added resistance prediction.

In this paper, a few approaches have been applied for the prediction of added resistance on different hull forms. The methods to be considered in this study are (i) slender-body method, (ii) Rankine panel methods, (iii) Cartesian-grid-based Euler solver, and (iv) short-wave approximations. Both the far- and near-field formations are considered in the slender-body and Rankine panel methods, while the direct pressure integration is applied for the CFD method. The computational results are validated by comparing them with experimental data on Wigley hull, Series 60 hull, and S175 containership, showing reasonable agreements for all models. The study is extended to the analysis of added resistance in short wavelengths.
Parameterization for Nonlinearity of Random Waves Over Slopes
Authors: Chen Hongzhou , Dong Guohai , Ma Yuxiang
Published: November 2013

Nonlinearity of gravity waves in coastal region plays crucial role in the wave evolution and the sediment transport. Parameterization of the nonlinear characteristics of random waves is an efficient and important way to descript the wave process. It is well known that coastal topography has a key effect on the wave transformation. However, the related previous studies have ignored the slope effects. It is the primary motivation of the research.

To implement this aim, physical experiments of random waves propagating over three slopes (1/15, 1/30, 1/45) were carried out in a wave flume with 50m long, 3m wide and used with a water depth of 0.52m. About 20 random wave simulations based on JONSWAP spectra with varying wave height and peak frequency were considered.

The wavelet based bispectrum is adopted to obtain the nonlinear parameters, bicoherence, biphase, skewness and asymmetry. On each slope bottoms, several empirical relationships between these parameters and the local Ursell number are derived using the least square method. The results indicate that the bicoherence and the asymmetry of waves relate to the slope. However, the slopes have negligible effect on the formulae of the skewness. Then, the empirical formulae on the bicoherence and asymmetry combining with the bottom slope are constructed.
Nonlinear Pitch Decay of a Floating Offshore Wind Turbine Structure
Authors: Thiagarajan K. P. , Urbina R. , Hsu W.
Published: November 2013

Model tests were conducted on three generic floating wind turbine systems in 2011, and reported in a series of papers at OMAE 2012. These tests were conducted at the MARIN facility in the Netherlands, by a consortium of universities, government research organizations and industry. As part of the testing program, decay tests in platform pitch were conducted with and without wind. It was found that for spar and semi-submersible type structures, resonant pitch motion was damped due to wind in storm sea conditions.

The nonlinear decay motion of a floating wind turbine platform is modeled using a one degree-of-freedom nonlinear oscillation equation about a mean offset angle. Attention is paid to the turbine thrust coefficient and its variability with respect to oncoming flow speed, which in turn is affected by the structure pitch motion. The equation of motion reveals that the mean offset position has an important role in the stiffness, damping and consequently the natural period of pitch motion. Several important dimensionless parameters are introduced.

The paper discusses a simple thrust model for an offshore wind turbine based on rudiments of blade element theory. Using the simplified thrust coefficient formulation, the increase in platform pitch damping due to wind is formulated. Experimental data reported from prior tests described above show good agreement with the theoretical model.
A Mesh Dependency Study for the Mean Drift Forces by Pressure Integration
Authors: Pan Zhi Yuan , Vada Torgeir , Hanssen Finn-Christian Wickmann
Published: November 2013

The convergence of drift force computation on a LNGC in shallow water is studied. It is found that the convergence of the result, especially for the pressure integration method, is largely dependent on the mesh quality. Furthermore, the irregular frequencies degenerate the results in the high frequency region. The LNGC analysis has numerical challenges related to the geometry and water depth. We also wanted to see if the convergence properties are due to this or if they are of more general nature.

To investigate this, an additional analysis was done for a Wigley ship in deep water. The convergence properties were found to be even poorer in this case. This shows that the convergence problem seems to be quite general. It is also found that the vertical components, which have to be evaluated by pressure integration, converge much better than the horizontal components. Hence all six components can be found using a moderately dense mesh by using the far field integration for the horizontal components and only the vertical components from the pressure integration.
Approach to Lateral Buckling and On-Bottom Stability Interaction Assessment
Authors: Anderson Benjamin , Shim Edwin , Zeitoun Hammam , Chin Eu Jeen
Published: November 2013

Lateral buckling and on-bottom stability are often considered independently during pipeline design. However, it is expected that the interaction between lateral buckling and on-bottom stability will become an increasingly common and important pipeline design consideration; as projects move into higher temperature / higher pressure (HT/HP) design conditions in areas of cyclonic metocean environments. The interaction of lateral buckling and on-bottom stability occurs mainly at shallow water depths. This interaction is not expected in deeper water depths where the hydrodynamic loading from storms is less significant at the sea floor.

The main challenges faced in assessing lateral buckling and stability interaction include; bounding storm-induced horizontal out-of-straightness (HOOS), capturing the increased tendency to buckling due to lift and inline forces from hydrodynamic loading, and the post-buckle response at unplanned and planned initiation sites during a storm event.

In cases where pipeline absolute stability cannot be assured, storm-induced HOOS can be introduced into the pipeline. This HOOS can govern the buckling design; rather than HOOS due to pipelay, or vertical out-of-straightness (VOOS) due to bathymetric features. In addition, the lift and inline forces due to the storm loading increases the tendency for pipelines to buckle, and increases the likelihood of rogue buckle formation. Subsequently, storm loading may play a significant role in terms of initiation and response of uncontrolled lateral buckling, and therefore the extents of buckle control schemes (if required).

Furthermore, it is important to consider the response at planned initiation sites under storm loading. Severe storm loading can result in significant lateral displacement of planned buckles; affecting the strains and bending moments in the pipeline and influencing the buckling design.

This paper outlines the approach and knowledge gained from recent experiences in the design of pipelines subject to lateral buckling and severe cyclonic metocean conditions. The insight gained can be applied to other systems where the interaction of lateral buckling and on-bottom stability is of a concern. In order to perform appropriate assessments, Wood Group Kenny used a number of advanced finite element (FE) models which simulate buckle responses under various sea states for on-seabed and at snake bend location.