bluuebunny/crossref_metadata_2025 huggingface dataset:
Foraging in a changing environment: habitat shifts of an oceanic predator over the last half century
Authors: Louzao Maite , Aumont Olivier , Hothorn Torsten , Wiegand Thorsten , Weimerskirch Henri
Published: June 2012

Spatial modelling studies stress the importance of predicting future species distribution in changing environments, but it is also important to establish historical distribution ranges of species to provide baseline conditions for understanding distribution shifts. We focused on pelagic ecosystems, the largest ecosystem on Earth. Based on boosting algorithms, we reconstructed the foraging patterns of an oceanic predator, wandering albatross Diomedea exulans, in the highly dynamic Southern Ocean over the last half century. To access the unobserved past oceanographic conditions, we used simulations of the OPA‐PISCES oceanic model for the 1958–2001 period. Firstly, we validated the simulated oceanographic variables (sea surface temperature and height, wind speed and chlorophyll a) for the 1998–2001 period with remotely sensed oceanographic data, which were highly correlated, except chlorophyll a. Secondly, we developed two habitat models (based on simulated and observed oceanographic variables) describing the foraging probability of albatrosses. We detected no statistically significant differences between the two models and predictions of both models matched the observed distribution patterns reasonably. Finally, we projected the most likely historical key pelagic habitats of albatross for the 1958 to 2001 period and characterised recurrent, occasional and unfavourable foraging areas in a decadal basis based on average predictions and their standard deviations. Our findings 1) provided a historical baseline (1958–1968) of recurrent, occasional and unfavourable foraging habitats, 2) evidenced a progressive habitat shift the following decades driven by a propagation of sea surface height from SE South Africa towards Antarctica from 1958 to 2001 and 3) measured habitat change rates of wandering albatross over the last half century. To our knowledge, our study provides the first quantitative long‐term assessment of the spatial response of a marine top predator to changing pelagic habitats of the Southern Ocean and highlighted the oceanographic mechanisms involved, offering new insights on future effects of climate change on the pelagic realm.
Terahertz wave techniques using a metal mesh for evaluating the components of the stratum corneum
Authors: Mizukoshi Koji , Yonekura Kazuki , Ogura Hidehiro , Guan Yu , Kawase Kodo
Published: June 2012

Background/purpose

Terahertz waves are located in the region of the spectrum between milliwaves and infrared. We analyzed the feasibility of terahertz spectroscopy to inspect the compositional variations of the stratum corneum (SC).

Methods

We used a terahertz time‐domain spectroscopy system with the metal mesh technique. To investigate whether terahertz can inspect compositional variation of SC, we measured the terahertz frequency spectra of the SC sheet that was treated with chloroform–methanol, lipid mixture, a denaturation agent, and heating with hot air.

Results

The chloroform–methanol treatment of the SC shifted the dip position, which represents a convex downward shape of the spectra, to a higher frequency. This dip shift was reversed to an untreated position by the dose‐dependent application of a lipid mixture. The heating treatment of the SC shifted the dip position to a higher frequency. The same dip shift was also induced by the application of a denaturation agent to the SC.

Conclusion

The technique using terahertz waves with a metal mesh is effective because of its simplicity and its high degree of accuracy in detecting the amount of lipid and the protein conformation state.
The involvement of N‐glycosylation of zona glycoproteins during meiotic maturation in sperm–zona pellucida interactions of porcine denuded oocytes
Authors: LAY Khin Mar , NAKADA Tadashi , TATEMOTO Hideki
Published: June 2012

The present study was conducted to delineate whether N‐glycosylation of zona pellucida (ZP) glycoproteins occurred during meiotic maturation and whether this N‐glycosylation played a role in sperm–ZP interactions of porcine cumulus denuded oocytes (DOs). After mechanical removal of cumulus cells from cumulus oocyte complexes (COCs), DOs were cultured for 44 h in in vitro maturation (IVM) culture. The experiments were carried out to determine the effects of tunicamycin, a specific N‐glycosylation inhibitor, for various intervals during IVM on sperm–ZP interactions in porcine DOs. The results determined that DOs could induce meiotic maturation, although the maturation rate of DOs was earlier than that of COCs. In addition, N‐glycosylation of ZP glycoproteins occurred during meiotic maturation and was crucial in sperm–ZP interactions, was responsible for sperm penetration, sperm binding to ZP and induction of acrosome reaction in ZP‐bound sperm. However, the inhibition of N‐glycosylation by tunicamycin during IVM did not influence ZP hardness and male pronuclear formation, indicating that this N‐glycosylation was involved in the initial stage of fertilization. We conclude that 24–44 h of N‐glycosylation of ZP glycoproteins during meiotic maturation was crucial in sperm penetration and sperm binding to ZP and the induction of acrosome reaction in sperm bound to ZP of porcine DOs.
ROBERT J. ALEXANDER'S U.S. LEFT‐WING INTERVIEW COLLECTION AND ARCHAEOLOGY OF DISSIDENT COMMUNISM
Authors: Devinatz Victor G.
Published: June 2012

Robert J. Alexander (1918–2010), a pioneering Latin American specialist, who focused much of his scholarship on the governmental systems, political parties, leaders and labor movements of Mexico, Central America and South America, is also known for his collection of an estimated 10,000–12,000 Latin American/Caribbean interviews amassed from the late 1940s to the turn of the twenty‐first century. During this same 50‐year period, Alexander, who also possessed a strong interest in U.S. radicalism, assembled a smaller interview collection of U.S. left‐wing activists that include those involved in Lovestoneite, Trotskyist, Shachtmanite, etc. organizations. In addition to his voluminous writings on Latin America, Alexander also devoted significant energy during the last three decades of his life to writing the history of dissident communist movements (i.e., the Communist Right Opposition, Trotskyism, and Maoism) throughout the world. The purpose of this article is to discuss and analyze Alexander's collection of interviews of U.S. political and labor radicals while critically examining his major works on dissident communism. In spite of the contributions he has made in these fields, I conclude that there are serious methodological flaws with Alexander's writings on dissident communism although his U.S. left‐wing interview collection of political and labor radicals is invaluable for the study of the twentieth‐century U.S. radicalism.
Is a Treatment Delay in Radical Prostatectomy Safe in Individuals with Low-Risk Prostate Cancer?
Authors: Sun Maxine , Abdollah Firas , Hansen Jens , Trinh Quoc-Dien , Bianchi Marco , Tian Zhe , Briganti Alberto , Shariat Shahrokh F. , Montorsi Francesco , Perrotte Paul , Karakiewicz Pierre I.
Published: June 2012

Introduction

Many patients diagnosed with localized prostate cancer (PCa) are presented with several treatment modalities, which may require time to understand these options before making an informed decision regarding treatment.

Aim

The aim of this study was to compare the effect of radical prostatectomy (RP) delay on postoperative functional outcomes and mortality in a North American population-based cohort.

Methods

Overall, 17,153 men treated with RP for non-metastatic clinical stage T1–2, low-grade PCa between years 1995 and 2005 within the U.S. Surveillance, Epidemiology, and End Results Medicare-linked database were abstracted.

Main Outcome Measures

The effect of treatment delay (from PCa diagnosis to RP of >3 months) on pathological upstaging at surgery (≥pT3) and postoperative functional outcomes (urinary incontinence and erectile dysfunction) was examined using logistic regression analyses. The 10-year PCa mortality rates were computed using cumulative incidence rates.

Results

Overall, 2,576 (15%) patients underwent RP > 3 months after diagnosis. A treatment delay of >3 months was associated with a 24% and 33% higher rate of erectile dysfunction diagnosis and procedure, respectively (both P ≤ 0.001). Treatment delay was also associated with 6% higher rate of urinary incontinence procedure (P = 0.01). Furthermore, a dose-response effect was detected with respect to increasing durations of RP delay (≤3 vs. 3–5 vs. 5–9 vs. ≥9 months) the rates of erectile dysfunction and urinary incontinence diagnoses/procedures. Treatment delay was not associated with pathological upstaging and PCa mortality.

Conclusions

Customarily, the timing of RP following biopsy is dictated by tumor aggressiveness. In general, patients with more unfavorable characteristics are operated sooner. This may obliterate the potential detriments of delayed RP. The treatment delay between biopsy and RP may result in more extensive periprostatic tissue resection and may adversely affect postoperative continence and erectile function.
Leisure activities among older Germans – a qualitative study
Authors: Boggatz Thomas
Published: June 2012

Boggatz T. (2013) Leisure activities among older Germans – a qualitative study.International Journal of Older People Nursing 8, 174–185   doi:10.1111/j.1748‐3743.2012.00332.x

Background.  Leisure activities contribute to well‐being and health in old age. Community nurses should consequently promote such activities among older persons. To do so they need an understanding of older persons’ interest in leisure activities. Social contacts, volunteering and pursuit of hobbies and interests constitute the main aspects of leisure.

Aims and objectives.  This study aimed to determine the attitudes of older Germans to these aspects to identify user types of leisure time facilities.

Design.  A qualitative study was conducted within a community‐based project in an industrial town in West Germany.

Methods.  Data were collected with semi‐structured guideline interviews and evaluated with qualitative content analysis according to Mayring.

Results.  With regard to social contacts attitudes ranged from limited need for contacts to being a reliable member in an older persons’ club. Social engagement is only found among the latter. Pursuit of hobbies and interest ranged from being a minimal user of leisure time facilities to refined expectations. Inflexible group structures may prevent potential users from participation despite having a programme in accordance with target group needs.

Conclusions.  Attitudes to leisure activities can be described as a combination of two dimensions: the degree of social involvement and the desired refinement of hobbies and interest.

Implications for practice.  Community nurses who organise social afternoons need to assess these attitudes and should steer social dynamics of in a way that facilitates access for newcomers.
Roles for claudins in alveolar epithelial barrier function
Authors: Overgaard Christian E. , Mitchell Leslie A. , Koval Michael
Published: June 2012

Terminal airspaces of the lung, alveoli, are sites of gas exchange that are sensitive to disrupted fluid balance. The alveolar epithelium is a heterogeneous monolayer of cells interconnected by tight junctions at sites of cell–cell contact. Paracellular permeability depends on claudin (cldn)‐family tight junction proteins. Of over a dozen alveolar cldns, cldn‐3, cldn‐4, and cldn‐18 are the most highly expressed; other prominent alveolar claudins include cldn‐5 and cldn‐7. Cldn‐3 is primarily expressed by type II alveolar epithelial cells, whereas cldn‐4 and cldn‐18 are expressed throughout the alveolar epithelium. Lung diseases associated with pulmonary edema, such as alcoholic lung syndrome and acute lung injury, affect alveolar claudin expression, which is frequently associated with impaired fluid clearance due to increased alveolar leak. However, recent studies have identified a role for increased cldn‐4 in protecting alveolar barrier function following injury. Thus, alveolar claudins are dynamically regulated, tailoring lung barrier function to control the air–liquid interface.
Association between segments of zonula occludens proteins: live‐cell FRET and mass spectrometric analysis
Authors: Rueckert Christine , Castro Victor , Gagell Corinna , Dabrowski Sebastian , Schümann Michael , Krause Eberhard , Blasig Ingolf E. , Haseloff Reiner F.
Published: June 2012

The tight junction protein ZO‐1 (zonula occludens protein 1) has recruiting/scaffolding functions in the junctional complex of epithelial and endothelial cells. Homodimerization was proposed to be crucial for ZO‐1 function. Here, we investigated the ability of ZO‐1 domains to mediate self‐interaction in living cells. We expressed ZO‐1 truncation mutants as fusions with derivatives of green fluorescent protein in tight junction–free HEK‐293 cells and determined self‐association by means of fluorescence resonance energy transfer measurements using live‐cell imaging. We show that both an SH3‐hinge‐GuK fusion protein and the PDZ2 domain self‐associate in our test system. The recombinant PDZ2 domain also binds to ZO‐1 and ZO‐2 in tight junction–forming HT29/B6 cell lysates, as demonstrated by coprecipitation. Both interaction types are of relevance for the function of ZO‐1 in the regulation of the junctional complex in polar cells.
Intensive care unit patients with 2009 pandemic influenza A (H1N1pdm09) virus infection – United States, 2009
Authors: Bramley Anna M. , Dasgupta Sharoda , Skarbinski Jacek , Kamimoto Laurie , Fry Alicia M. , Finelli Lyn , Jain Seema ,   for the 2009 Pandemic Influenza A (H1N1) Virus Hospitalizations Investigation Team
Published: June 2012

Please cite this paper as: Bramley et al. Intensive care unit patients with 2009 pandemic influenza A (H1N1pdm09) virus infection – United States, 2009. Influenza and Other Respiratory Viruses 6(601), e134–e142.

Background  The influenza A (H1N1pdm09) [pH1N1] virus resulted in intensive care unit (ICU) admissions, acute respiratory distress syndrome (ARDS), and death.

Objectives   To describe the characteristics of ICU patients with pH1N1 virus infection in the United States during the spring and fall of 2009 and to describe the factors associated with severe complications including ARDS and death.

Patients/Methods   Through two national case‐series conducted during spring and fall of 2009, medical charts were reviewed on ICU patients with laboratory‐confirmed pH1N1 infection by real‐time reverse‐transcriptase polymerase chain reaction.

Results   The majority (77%) of 154 patients hospitalized in an ICU were <50 years of age, and 65% had at least one underlying medical condition. One hundred and twenty‐eight (83%) patients received influenza antiviral agents; 29% received treatment ≤2 days after illness onset. Forty‐eight (38%) patients developed ARDS and 37 (24%) died. Patients with ARDS were more likely to be morbidly obese (36% versus 19%, P = 0·04) and patients who died were less likely to have asthma (11% versus 28%, P = 0.05). Compared with patients who received treatment ≥6 days after illness onset, patients treated ≤2 days after illness onset were less likely to develop ARDS (17% versus 37%, P < 0.01) or die (7% versus 35%, P < 0·01).

Conclusions   Among patients hospitalized in an ICU with pH1N1 virus infection, ARDS was a common complication, and one‐quarter of patients died. Patients with asthma had less severe outcomes. Early treatment with influenza antiviral agents was likely beneficial, especially when initiated ≤2 days after illness onset.
Physicochemical Properties and Antioxidant Activities of Korean Traditional Alcoholic Beverage, Yakju, Enriched with Mulberry
Authors: Jung Kwak Eun , Yeon Lee Ji , Sook Choi Il
Published: June 2012

Abstract:  Mulberry fruits (Morus alba L.), rich in health beneficial compounds such as polyphenols, flavonoids, and anthocyananis, have traditionally been used as nutritional foodstuffs and fork medicines. In this study, physicochemical properties and antioxidant activities of a traditional Korean alcoholic beverage ``yakju'' enriched with mulberry were evaluated. The beverage was enriched with smoothies prepared from Korean mulberry cultivars of Cheongilppong (CP), Suwonppong (SP), and Daesungppong (DP). In comparison to the control, an increase in alcohol content and total acidity and a decrease in sugar level in yakju enriched with mulberry were observed during 15 d of fermentation. The total polyphenol and total flavonoid content increased in the following order: DP yakju > SP yakju > CP yakju > control yakju. In contrast, the anthocyanin content decreased during the fermentation periods. The trans‐resveratrol content of mulberry yakju increased during the fermentation and the resveratrol content of DP yakju (0.24 mg/L) was significantly higher than that of SP yakju (0.21 mg/L) and CP yakju (0.14 mg/L) on the 15th day of fermentation (P < 0.05). The antioxidant activities of mulberry yakju, which was assessed using the 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH), 2,2′‐azino‐bis‐(3‐ethylbenozothiazoline‐6‐sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and reducing power assays, decreased during the 1st day of fermentation and increased into thereafter. The increase in antioxidant activities of mulberry yakju might have been affected primarily by the total flavonoid and total polyphenol content with increasing alcohol concentration, as a good extractor, during the fermentation; however, the antioxidant activities may have also been affected by the total anthocyanin content up to the 1st day of fermentation.

Practical Application:  The physicochemical properties and antioxidant activities of a traditional Korean alcoholic beverage ``yakju'' enriched with mulberry were investigated. This analysis is important for the potential applications of mulberry yakju as functional alcoholic drinks.
Applying clinical staging to young people who present for mental health care
Authors: Hickie Ian B. , Scott Elizabeth M. , Hermens Daniel F. , Naismith Sharon L. , Guastella Adam J. , Kaur Manreena , Sidis Anna , Whitwell Bradley , Glozier Nicholas , Davenport Tracey , Pantelis Christos , Wood Stephen J. , McGorry Patrick D.
Published: June 2012

Aim: The study aims to apply clinical staging to young people who present for mental health care; to describe the demographic features, patterns of psychological symptoms, disability correlates and clinical stages of those young people; and to report longitudinal estimates of progression from less to more severe stages.

Methods: The study uses cross‐sectional and longitudinal assessments of young people managed in specialized youth clinics. On the basis of clinical records, subjects were assigned to a specific clinical ‘stage’ (i.e. ‘help‐seeking’, ‘attenuated syndrome’, ‘discrete disorder’ or ‘persistent or recurrent illness’).

Results: Young people (n = 209, mean age = 19.9 years (range = 12–30 years), 48% female) were selected from a broader cohort of n = 1483 subjects. Ten percent were assigned to the earliest ‘help‐seeking’ stage, 54% to the ‘attenuated syndrome’ stage, 25% to the ‘discrete disorder’ stage and 11% to the later ‘persistent or recurrent illness’ stage. The interrater reliability of independent ratings at baseline was acceptable (κ = 0.71). Subjects assigned to the ‘attenuated syndrome’ stage reported symptom and disability scores that were similar to those assigned to later stages. Longitudinally (median = 48 weeks), transition to later clinical stages were 11% of the ‘help‐seeking’, 19% of the ‘attenuated syndrome’ and 33% of the ‘discrete disorder’ groups.

Conclusion: Among young people presenting for mental health care, most are clinically staged as having ‘attenuated syndromes’. Despite access to specialized treatment, a significant number progress to more severe or persistent disorders.
Standardized ‘no‐touch’ donor tissue preparation for DALK and DMEK: harvesting undamaged anterior and posterior transplants from the same donor cornea
Authors: Groeneveld‐van Beek Esther A. , Lie Jessica T. , van der Wees Jacqueline , Bruinsma Marieke , Melles Gerrit R. J.
Published: June 2012

Purpose:  To describe a standardized ‘no‐touch’ harvesting technique of anterior and Descemet membrane (DM) grafts for use in deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK), which provides undamaged anterior and posterior corneal grafts.

Methods:  A retrospective evaluation was performed of our standard method for harvesting DM grafts and DALK grafts (Technique I; n = 31) versus a newly designed ‘no‐touch’ technique (Technique II; n = 31), in which a peripheral ring of trabecular meshwork tissue is left in‐situ, and the DM graft is trephined on an underlying soft contact lens. Endothelial cell density (ECD) before and immediately after DM stripping was used as the main outcome parameter.

Results:  Endothelial cell density did not differ within Techniques I and II (before versus after DM stripping) (p = 0.75 and p = 0.54, respectively) or among Techniques I and II (p = 0.61). With the latter technique, anterior corneal grafts and posterior DM grafts could be harvested with negligible damage to the endothelial cell layer or the posterior stromal bed. All 93 grafts (62 DM grafts) were eligible for transplantation, and six months post‐operatively all transplants used were functional.

Conclusion:  The new technique offers the following advantages: (i) production of ‘undamaged’ grafts for DALK and DMEK, (ii) better controlled tissue handling of the thin DM graft during DM stripping and (iii) an increase in availability of corneal grafts obtained from the same donor tissue pool.
Are Analysts' Cash Flow Forecasts Naïve Extensions of Their Own Earnings Forecasts?
Authors: Call Andrew C. , Chen Shuping , Tong Yen H.
Published: June 2012

We examine the sophistication of analysts' cash flow forecasts to better understand what accrual adjustments, if any, analysts make when forecasting cash flows. As a preliminary step, we first demonstrate that prior empirical tests used to evaluate the sophistication of analysts' cash flow forecasts are not diagnostic. We then present three sets of evidence to triangulate our conclusion that analysts' cash flow forecasts incorporate meaningful accrual adjustments. First, we review a stratified random sample of 90 analyst reports and find that the majority of these analysts include explicit adjustments for working capital and other accruals in their cash flow forecasts. Second, using a large sample of analysts' cash flow forecasts from 1993–2008, we find that these forecasts outperform time‐series cash flow forecasts in correctly predicting the sign and magnitude of accruals. Finally, we find a significant market reaction to analysts' cash flow forecast revisions, suggesting that investors find these revisions informative. Collectively, our findings demonstrate that analysts' cash flow forecasts are not simply naïve extensions of their own earnings forecasts, but that they reflect meaningful and useful accrual adjustments. These findings are relevant to researchers who examine analysts' cash flow forecasts in a variety of settings, and to investors and practitioners who employ these forecasts for valuation purposes.
Buckling of a Clamped-Free Double-Walled Carbon Nanotube by the Bubnov-Galerkin Method
Authors: Elishakoff Isaac , Bucas Simon
Published: June 2012

This study deals with the Bubnov-Galerkin method applied to the buckling of clamped-free double-walled carbon nanotubes (DWCNTs) subjected to a concentrated compressive load at the free end. It was found that at least four comparison functions are needed in order to obtain accurate results.
Proper Inclusion of Interiorly Applied Loads With Beam Theory
Authors: Ho Jimmy C. , Yu Wenbin , Hodges Dewey H.
Published: June 2012

An error is introduced by the conventional approach of applying beam theory in the presence of interiorly applied loads. This error arises from neglecting the influence of the precise distribution of surface tractions and body forces on the warping displacements. This paper intends to show that beam theory is capable of accounting for this influence on warping and accomplishes this by the variational asymptotic method. Correlations between elasticity solutions and beam solutions provide not only validations of beam solutions, but also illustrate the resulting errors from the conventional approach. Correlations are provided here for an isotropic parallelepiped undergoing pure extensional deformations and for an isotropic elliptic cylinder undergoing pure torsional deformations.
Numerical Experiments of Solving Moderate-Velocity Flow Field Using a Hybrid CFD-MD Approach
Authors: Ko Soon-Heum , Kim Nayong , Jha Shantenu
Published: June 2012

We propose numerical approaches to reduce the sampling noise of a hybrid computational fluid dynamics (CFD) - molecular dynamics (MD) solution. A hybrid CFD-MD approach provides higher-resolution solution near the solid obstacle and better efficiency than a pure particle-based simulation technique. However, applications up to now are limited to extreme velocity conditions, since the magnitude of statistical error in sampling particles’ velocity is very large compared to the continuum velocity. Considering technical difficulties of infinitely increasing MD domain size, we propose and experiment a number of numerical alternatives to suppress the excessive sampling noise in solving moderate-velocity flow field. They are the sampling of multiple replicas, virtual stretching of sampling layers in space, and linear fitting of multiple temporal samples. We discuss the pros and cons of each technique in view of solution accuracy and computational cost.
Numerical Simulation of Turbulent Flow Past a Serrated Airfoil
Authors: Han Changhwa , Omori Takeshi , Kajishima Takeo
Published: June 2012

Despite a lot of experimental investigations, the effect of airfoil serrations on the reduction of discrete frequency noise (DFN) is not fully understood. We apply the large-eddy simulation (LES) to the turbulent flow around the NACA0012 airfoil without angle of attack in a uniform stream. In this case, a major source of aerodynamic noise is quasi two-dimensional spanwise vortices, which take place near the trailing edge. We therefore investigate the effect of serration in the trailing edge side. The depth of the serration is 10% of chord length. To take into account the weak compressibility at low Mach number, we made a particular modification to the pressure equation. One equation dynamic model for the subgrid scale stress is used for LES. These techniques have originally been developed in our research group. The serration successfully reduced the pressure fluctuations on the surface of the airfoil near the trailing edge. The observed structure of the density variation suggests that this modification contributes to the reduction of sound source.
Effect of Small-Amplitude Heaving Oscillations on the Flow Structure Above a Low-Aspect Ratio Wing
Authors: Visbal Miguel R.
Published: June 2012

Unsteady low-Reynolds-number flows are of importance in understanding the flight performance of natural flyers, as well as in the design of small unmanned air vehicles and micro air vehicles [1,2]. The imposed motion of flapping wings or the large excursions in effective angle of attack during gust encounters may induce the formation of dynamic-stall-like vortices [3–10] whose evolution and interaction with the aerodynamic surfaces impact both flight stability and performance.
Thermal Fluid Flow Transport Characteristics in Confined Channels With Two-Dimensional Dual Jet Impingement
Authors: Senkal Caner , Torii Shuichi
Published: June 2012

The flow and heat transfer characteristics of laminar dual circular jet impinging on a heating plate with inclined confinement surface has been investigated numerically. Governing equations in steady state are solved by a control volume based finite-difference method. The simulations have been carried out for Reynolds number (250≤Re≤418), the angle of inclination of the confined upper wall (0 ≤ θ ≤ 10), circular jet to annular jet velocity ratio (0≤VR≤2) and jet to target plate distances between 2D and 8D where D is the outer diameter of dual jet.SIMPLE algorithm was used to obtain velocity and temperature fields. Hybrid difference scheme is adopted for the discretized terms in the governing equations. The discretised equations are solved iteratively using the tridiagonal matrix algorithm line solver. Heat transfer performance along the heated wall is amplified with an increase in the velocity ratio and the Reynolds number. On the contrary, a substantial reduction in the heat transfer rate, for VR = 0.0, occurs in the stagnation zone, because the absence of the inner nozzle injection causes the recirculation in the corresponding region. The heat transfer rate in the stagnation zone is attenuated by increasing the jet nozzle to impinging plate distance. In particular, the effect of the inclination angle in the down-stream region, especially at the vicinity of outlet, is major then other effects Nusselt number distribution on the impingement plate is affected by inclined upper wall because inclination of the wall accelerates the exhaust flow. The streamwise reduction in the heat transfer rate for θ = 0° is suppressed by the presence of the inclined confinement surface and its value is intensified by the inclination angle.
Parametric Investigation on the Effect Factors for Liquid Droplet Impingement Erosion
Authors: Li Rui , Ninokata Hisashi , Mori Michitsugu
Published: June 2012

Liquid droplet impingement (LDI) erosion could be regarded to be one of the major causes of unexpected troubles occasionally occurred in the inner bent pipe surface. Evaluating the LDI erosion is an important topic of the thermal hydraulics and structural integrity in aging and life extension for nuclear power plants safety. In order to investigate the effect of various parameters, such as droplet diameter, droplet velocity and injected droplet number, on the erosion rate induced by LDI, droplet impingement under different conditions are conducted numerically by a two-phase computational approach. Considering the carrier turbulence kinetic energy attenuation due to the involved droplets, numerical simulations have been performed by using two-way vapor-droplet coupled system. This computational fluid model is built up by incompressible Reynolds Averaged Navier-Stoke equations using standard k-ε model and the SIMPLE algorithm, and the numerical droplet model adopts the Lagrangian approach, a general LDI erosion prediction procedure for bent pipe geometry has been performed to supplement an available CFD code. A correlation for the erosion rate in terms of droplet velocity, diameter and volume fraction is purposed for the engineers’ maintenance reference. Based on our computational results, comparison with an available accident data was made to prove that our methodology could be an appropriate way to simulate and predict the bent pipe wall thinning phenomena.
Design and Analysis of Nonlinear Viscoelastic Damper
Authors: Ashrafi Nariman , Eskafi Mohamad Reza
Published: June 2012

A custom-made nonlinear viscoelastic damper is designed for several industrial applications. The damper is structurally similar to typical commercial dampers and the design is solely based on the choice of the viscoelastic material used as damping agent in the damper. With rheological parameters of a selected material from experiment, the coefficients of Johnson-Segalman constitutive equation model are evaluated by fitting the data. The problem was first formulated by writing the governing equations for the flow over flat plate. A numerical scheme of finite difference method is applied to solve the governing equations in time domain. The model is capable of predicting the nonlinear amplitude-dependent behavior of viscoelastic dampers under single and multiple-frequency excitations.
Turbulent Impinging Jet Into a Rigid Porous Layer
Authors: de Lemos Marcelo J. S.
Published: June 2012

This work shows simulations for a turbulent jet impinging against a flat plane covered with a layer of permeable and thermally conducting material. Distinct energy equations are considered for the porous layer attached to the wall and for the fluid that impinges on it. Parameters such as Reynolds number, porosity, permeability, thickness and thermal conductivity of the porous layer are varied in order to analyze their effects on the local distribution of Nu. The macroscopic equations for mass, momentum and energy are obtained based on volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer eliminates the peak in Nu at the stagnation region. For highly porous and highly permeable material, simulations indicate that the integral heat flux from the wall is enhanced when a thermally conducting porous material is attached to the wall.
Multiscale Issues in DNS of Multiphase Flows
Authors: Aboulhasanzadeh Bahman , Thomas Siju , Lu Jiacai , Tryggvason Gretar
Published: June 2012

In direct numerical simulations (DNS) of multiphase flows it is frequently found that features much smaller than the “dominant” flow scales emerge. Those features consist of thin films, filaments, drops, and boundary layers, and usually surface tension is strong so the geometry is simple. Inertia effects are also small so the flow is simple and often there is a clear separation of scales between those features and the rest of the flow. Thus it is often possible to describe the evolution of this flow by analytical models. Here we discuss two examples of the use of analytical models to account for small-scale features in DNS of multiphase flows. For the flow in the film beneath a drop sliding down a sloping wall we capture the evolution of films that are too thin to be accurately resolved using a grid that is sufficient for the rest of the flow by a thin film model. The other example is the mass transfer from a gas bubbly rising in a liquid. Since diffusion of mass is much slower than the diffusion of momentum, the mass transfer boundary layer is very thin and can be captured by a simple boundary layer model.
Particulate Flow Simulation by the Immersed Boundary Lattice Boltzmann Method
Authors: Seta Takeshi
Published: June 2012

We demonstrate the applicability of the immersed boundary lattice Boltzmann method (IB-LBM) based on the implicit correction method to the simulation of rigid body motion in a viscous fluid and to the natural convection calculation. We compare the accuracy of the IB-LBM based on the implicit correction method with one of the IB-LBM based on the direct forcing method that eliminates the necessity of the determination of free parameters. In the simulations of the cylindrical Couette flow and of the heat transfer between two concentric cylinders, the implicit correction method indicates the first-order accuracy in the number of Lagrangian points. The accuracy of the IB-LBM based on the direct forcing method is independent of the number of the boundary points. The IB-LBM based on the implicit correction method is more accurate than one based on the direct forcing method.
Two Dimensional Droplet Deformation on Moving Wall in a Channel
Authors: Kim H. R. , Yoon H. S. , Jeong H. K. , Ha M. Y.
Published: June 2012

A two-dimensional immiscible droplet deformation phenomena on moving wall in a channel has been simulated using lattice Boltzmann method. The behavior of the droplet is shown with the effects of the contact angle, the velocity of bottom wall, droplet size of the droplet to the displacement fluid are investigated. At the initial state, a droplet with various contact angle between the bottom wall is formatted on the wall in a quiescent fluid. When the bottom moves, the shape of droplet starts to deform. The three patterns of deformation of the droplet corresponding to the contact have been shown in the present study.
Numerical Study of Advection Schemes for Interface Capturing in a Volume of Fluid Method on Unstructured Meshes
Authors: Shan Hua , Kim Sung-Eun
Published: June 2012

In solving naval hydrodynamics problems using computational fluid dynamics (CFD), the moving free surface between air and water introduces extra difficulties to numerical methods, since the material property jumps across the interface and the time-dependent free surface position becomes part of the solution. Engineering applications often require a flexible and robust solver for incompressible multi-phase viscous flows with the capability of capturing the interface. In the volume of fluid (VOF) method, the interface is captured by directly solving the convection transport equation of volume fraction. In this case, the numerical dissipation of the advection scheme smears the sharp interface and the numerical dispersion causes unphysical oscillations near the interface. Utilizing the guidance of boundedness criteria, many limited higher-order non-liner advection schemes have been developed in an attempt to balance numerical dissipation and dispersion. Though it is well-known that these non-linear advection schemes can lead to solutions combining boundednesss and accuracy, users are often overwhelmed by the wide variety of available schemes. Also, these schemes are developed with the assumption of a uniform Cartesian-type mesh. Thus, a thorough investigation and comparison of the performance of these interface-capturing advection schemes are necessary, especially for naval hydrodynamics problems solved on unstructured meshes. In this study, a systematic comparison and evaluation of several existing and new bounded, higher-order advection schemes has been conducted within the framework of NavyFOAM, which is developed based on OpenFOAM — an object orientated C++ toolbox for the customization and extension of numerical solvers for continuum mechanics problems, including CFD, where the governing equations are discretized using the cell-centered finite volume method on unstructured mesh. The flexible infrastructure of the code enables us to implement and test the selected advection schemes very quickly. The test cases include advection of hollow cylinders, Zalesak’s rotating slotted disk, traveling solitary wave, dam breaking problem.
Application of the Lattice-Boltzmann-Method in Two-Phase Flow Studies: From Point-Particles to Fully Resolved Particles
Authors: Dietzel M. , Ernst M. , Sommerfeld M.
Published: June 2012

The Lattice-Boltzmann-Method (LBM) is a powerful and robust approach for calculating fluid flows in complex geometries. This method was further developed for allowing the calculation of several problems relevant to particle-laden flows. For that purpose two approaches have been developed. The first approach concerns the coupling of the LBM with a classical Lagrangian procedure where the particles are considered as point-masses and hence the particles and the flow around them are numerically not resolved. As an example of use, the flow through a single pore was considered and the deposition of nano-scale particles was simulated. The temporal evolution of the deposit structures is visualised and both the filtration efficiency and the pressure drop are simulated and compared with measurements. In the second developed LBM-approach, the particles are fully resolved by the numerical grid whereby the flow around particles is also captured and it is possibly to effectively calculate the forces on complex particles from the bounce-back boundary condition. As a case study the flow around spherical agglomerates consisting of mono-sized spherical primary particles is examined. Using local grid refinement and the curved wall boundary condition accurate simulations of the drag coefficient of such complex particles could be performed. Especially the effect of porosity on the drag was analysed. Finally, a scenario with moving particles was considered, namely, the sedimentation of a cluster of particles. In these simulations the primary particles were allowed to stick together and form agglomerates.
Full Scale Simulations of the Bubbly Flow Around the Research Vessel Athena With Incoming Waves and Discretized Propeller
Authors: Castro Alejandro M. , Carrica Pablo M.
Published: June 2012

Simulations of the two-phase bubbly flow around the research vessel Athena are presented. These are performed using a polydisperse model where several bubbles sizes are modeled. Intergroup transfer mechanisms such as breakup, coalescence and dissolution of air into water are considered. These simulations are performed on the fully appended Athena R/V including the rotating propeller. In this way the interaction of the stream of bubbles pushed down by the ship and the propeller is explicitly taken into account. Incoming regular waves are included in the simulations to mimic the observations of available data that show a pulsating entrainment of bubbles due to the waves. The effect of the several intergroup transfer mechanisms on the bubbly field around the ship is analyzed and discussed in depth. Simulations are performed in full scale to predict realistic turbulent structures and allow for a valid comparison with experiments.
Three Dimensional Optimum Design of a Steam Turbine Stage With NURBS Curves
Authors: Tejima Tomohiro , Niizeki Yoshiki , Shibukawa Naoki , Onoda Akihiro , Watanabe Satoru , Yuan Xin , Lin Zhirong , Zhu Xiaofeng
Published: June 2012

Progress in the computer performance has enabled automatic optimization of the three dimensional shape of turbine blades with a large number of large-scale CFD (Computational Fluid Dynamics) calculations. This paper presents an advanced aerodynamic optimization system for turbine blades. The system can automatically find improved blade shapes that give better aerodynamic performance in a turbine stage and reduces human efforts to generate blade shape data, computational mesh, CFD input data etc. The system consists of three parts; parameter updating part, blade shape generation part, and aerodynamic performance evaluation part. In the parameter updating part, users can choose DOE (Design of Experiment) or evolutionary optimization method such as GA (Genetic Algorithm), ASA (Adaptive Simulated Annealing), etc. to define the parameters in each step. The shape generation part changes the blade shapes using NURBS curves whose control point parameters are defined in the parameter updating part. Three-dimensional CFD grid is automatically generated for the changed blade shapes and steady CFD calculation is used to evaluate the aerodynamic performance of the changed blades in a turbine stage. Stagger angle distribution in the radial direction was thought as one of the important design parameters of turbine blades because it determines the flow pattern in radial direction. Then it was chosen as an optimized parameter with NURBS curves in this system. First, DOE was used for the human optimization, in which the parameter range for the advanced optimization was estimated and the best shape obtained was used as the initial shape for the evolutionary optimization to explore better blade shape parameters. Stage loss of an exhaust stage of IP (Intermediate Pressure) turbine which contains relatively high aspect ratio was chosen as the objective. In spite that such kind of stage was considered not to be sensitive to three dimensional stacking, the results showed good performance enhancement.
Radial Thrust of Single-Blade Centrifugal Pump
Authors: Nishi Yasuyuki , Fukutomi Junichiro , Fujiwara Ryota
Published: June 2012

A single-blade centrifugal pump is widely used as a sewage pump. However, a single-blade is acted on by a large radial thrust during the pump operation because of the geometrical axial asymmetry of the impeller. Therefore to secure the pump reliability, it is necessary to grasp the radial thrust quantitatively and elucidate a behavior and a generation mechanism. This study investigated the radial thrust acting on a single-blade centrifugal impeller by an experiment and a CFD analysis, and the results clearly indicated the following facts. The fluctuating component of the radial thrust increased as the flow rate changed from the design flow rate to a partial or excessive flow rate. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum and pressure components by applying unsteady conservation of momentum to this impeller. The grand total of these components was in agreement with the radial thrust calculated by integrating the pressure and the shearing stress on the impeller surface. In addition the behavior of each component was shown and the effects of those components that gave to the radial thrust were clarified. The pressure component had the greatest effect on a time-averaged value and a fluctuating component of the radial thrust. The time-averaged value of the inertia component was approximately 0 even if the flow rate changed. But its fluctuating component had a magnitude nearly comparable to the pressure component at a partial flow rate and slightly decreased with increase of the flow rate.
Analysis of Pressure Loading on Inducer Blades
Authors: Wu Yuzhen , Huang Hao
Published: June 2012

A typical inducer has a lower breakdown NPSH (net positive suction head when loss of headrise occurs) than that of centrifugal impeller. It is an axial impeller with special design features that allow pump operation under cavitation or partial cavitation condition. The design principle of inducer is to obtain appropriate head rise with low power consumption and good anti-cavitation capability. The failures of inducer are mainly caused by cavitation, but always involve other factors. Through numerical simulation and experimental analysis, the pressure loading on blades that affect the bending strength of blades is obtained. This paper studies pressure loading on inducer blades of the study object at steady and unsteady state.
Thermodynamic Effect and Cavitation Performance of a Cavitating Centrifugal Pump
Authors: Tanaka Teiichi
Published: June 2012

The thermodynamic effect which affects the cavitation performance of a cavitating centrifugal pump was investigated experimentally using liquid nitrogen. To measure the pump cavitation performance, a test setup which could carry out experiments using both liquid nitrogen and cold water was constructed. The test setup consisted of a suction tank, a test pump, a mass flow meter, a ball valve and pipes. Vacuum-insulated pipes were used. The test pump was a centrifugal type magnetic pump, and two impellers, which differed in cavitation performance, were used in experiments. Cavitation performance using liquid nitrogen or cold water could be obtained from the measurement of the pump suction and delivery pressure, the pump suction and delivery temperature, and the discharge flow rate. And an improvement in pump cavitation performance could be seen when comparing the experimental results from using liquid nitrogen with those from using cold water. The experimental results indicated that cavitation performance using liquid nitrogen was better than that using cold water. This improvement in cavitation performance was thought to be due to the thermodynamic effect of cavitation. And the estimated temperature depression due to the thermodynamic effect decreased with a decreasing flow coefficient. Moreover, it was shown that the estimated temperature depression due to the thermodynamic effect on the low cavitation performance impeller was larger than that on the high cavitation performance impeller at the same flow coefficient.