bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Gliadin/Glutenin and HMW‐GS/LMW‐GS Ratio on Dough Rheological Properties and Bread‐Making Potential of Wheat Varieties
Authors: Dhaka Vandana , Khatkar B.S.
Published: March 2015

The gliadin/glutenin ratio of 15 diverse wheat varieties ranged from 0.75 to 1.16, whereas the high molecular weight glutenin subunits (HMW‐GS) to low molecular weight glutenin subunits (LMW‐GS) ratio of these varieties ranged from 0.31 to 0.93. Gliadin/glutenin ratio showed a significant negative relationship with specific loaf volume (r = −0.73), dough development time (DDT; r = −0.73), dough stability (r = −0.79) and positive associations with LMW quantity (r = 0.72). Mixolab classified the wheat varieties into two groups on the basis of HMW‐GS located at Glu‐A1 and Glu‐D1. Wheat varieties HI 977 and DBW 16 with subunits 2* and 5 +10 at Glu‐A1 and Glu‐D1, respectively, exhibited the characteristics of “extra strong” doughs with longer DDT of 8.3 and 7.2 min, and higher dough stability values of 9.1 and 8.6 min, respectively. Wheat varieties C 306, HW 2004 with null allele at Glu‐A1 and 2 + 12 at Glu‐D1, in contrast, were weak as they developed quickly, with low dough stability (≤4 min).

Practical Applications

Bread has been one of the principal forms of food for man from the earliest times. Bread quality is determined by the composition and molecular structure of gluten which in turn controls the interactions of gluten subfractions during processing. Rheological properties, microstructure of gluten, gliadin/glutenin ratio and HMW‐GS/LMW‐GS ratio have been found to be associated with bread‐making quality of wheat varieties. The research implications may be utilized both by industry personnel as well as researchers to assess the bread‐making quality of wheat varieties.
School‐ and Family‐Level Socioeconomic Status and Health Behaviors: Multilevel Analysis of a National Survey in Wales, United Kingdom
Authors: Moore Graham F. , Littlecott Hannah J.
Published: March 2015

BACKGROUND

Interventions to address inequalities in adolescent health behaviors often target children from less affluent families, or schools in poorer areas. Few studies have examined whether school‐ or family‐level affluence predicts health behaviors independently, or in combination.

METHODS

This article reports secondary analysis of the Welsh Health Behavior in School‐aged Children (HBSC) survey. Mixed‐effects logistic regression models test associations of school and family socioeconomic status (SES) with smoking, fruit and vegetable consumption, alcohol consumption, and physical activity.

RESULTS

Higher family SES was associated with healthier behaviors, except in relation to alcohol consumption. For all behaviors except physical activity, school‐level SES was independently associated with healthier behaviors. In higher SES schools, a stronger association of family SES with health behavior was observed, particularly in relation to smoking and physical activity.

CONCLUSIONS

School and family SES may exert independent and combined influences upon adolescent health behaviors. Targeting interventions toward deprived schools may fail to address substantial inequalities within more affluent schools. Targeting deprived families may fail to address behaviors of children from affluent families, attending more deprived schools. Identifying universal health improvement interventions which have greater effects among children from poorer backgrounds may be a more effective means of reducing inequalities.
Absenteeism, Educational Plans, and Anxiety Among Children With Incontinence and Their Parents
Authors: Filce Hollie G. , LaVergne Leslie
Published: March 2015

BACKGROUND

Children with incontinence have more absenteeism, poorer academic performance, and potential social difficulties during the school years. These children and their parents are at risk for illness‐related anxiety. Whereas educational plans are designed to remediate educational, medical, and social‐emotional barriers at school, little research has explored the relationship among absenteeism, educational plans, and anxiety for this population.

METHODS

Eighty‐three families provided demographic information and completed either the Revised Children's Manifest Anxiety Scale Second Edition (RCMAS‐2) or the Adult Manifest Anxiety Scale (AMAS‐A). A multiple regression analysis was conducted to determine the relationships among these variables.

RESULTS

Children with chronic illness resulting in incontinence had greater than expected rates of absenteeism. A high level of absenteeism was a significant predictor of parental anxiety, but not child anxiety. Over one third reported having no plan in place to support the child's needs at school. However, when a plan was present, it had no impact on child or parental anxiety.

CONCLUSIONS

Absenteeism contributes to familial anxiety and educational difficulties. Despite the potential for educational plans to support these children at school, these plans are underutilized for children with incontinence. This population requires more attention to their academic and social‐emotional well‐being at school.
Girls and Boys Gambling With Health and Well‐Being in Finland
Authors: Räsänen Tiina , Lintonen Tomi , Joronen Katja , Konu Anne
Published: March 2015

BACKGROUND

The aim of this study was to examine the associations among gambling frequency, health status, health risk behavior, and sexual risk‐taking among eighth and ninth grade boys and girls (N = 101,167).

METHODS

Data were obtained from the nationwide School Health Promotion Study conducted in Finland 2010 and 2011. Outcome measures were adolescents' health and sexual behavior. Associations with gambling frequency were studied separately for boys and girls using polychotomous logistic regression models where grade level was adjusted.

RESULTS

Approximately 62% of adolescents had gambled during the previous year. Gambling was more common among boys than girls in both grade levels. Gambling frequency was associated with several health and sexual risk‐taking indicators such as signs of school burnout, staying up late, and having more than 1 sexual partner. Those who gambled the most had a higher risk for poorer health and taking health risks. Girls and those who had gambled on a weekly basis were the most vulnerable groups.

CONCLUSIONS

It would be beneficial to raise teacher, parent, and adolescent awareness of the wide range of negative health outcomes and risks associated with gambling.
Infrastructure of Participant Direction for Medicaid‐Funded In‐Home Autism Services for Children in Massachusetts
Authors: Leutz Walter , Warfield Marji E. , Timberlake Maria , Chiri Giuseppina
Published: March 2015

Although the prevalence of autism spectrum disorders (ASDs) among young children has grown, it has been noted that affected low‐income children and children from ethnic and racial minority families are less likely to be diagnosed with ASD and to receive services. To help address such disparities, the Autism Division of the Massachusetts Department of Developmental Services instituted an Autism Waiver Program funded jointly by the Commonwealth of Massachusetts and the U.S. federal government. The program was designed to help low‐income children with autism under age nine from diverse cultural backgrounds gain access to therapeutic supports. The program used a participant (parent)‐directed model to help families to choose and manage services, staff, and their own budget. The authors detail a study that was designed to evaluate the costs and factors contributing to “successful operations.” The authors gathered data from a focus group, reviewed cost data, and conducted individual qualitative interviews with staff involved in the coordination, delivery, and reimbursement of the program's services. They found that factors that contributed to successful operations included educated/trained families, skilled in‐home therapists, clear communication with families and among staff, good information systems, and participation of families in “carryover” of interventions. Families varied in their capacities and time to choose and manage services, but staff adjusted their levels of assistance to compensate. Of the total program budget, individual budgets comprised 82% and administrative costs comprised 18% of the expenses. Program staff were generally satisfied with the structure and operation of the program. Areas for improvement included simplifying record keeping, payments with online systems, and developing approaches to strengthen carryover.
Labelling Shakespeare's ‘Last Plays’
Authors: Chen Xing
Published: March 2015

Written near the end of the playwright's career and generically and stylistically distinct, Shakespeare's ‘last plays’ have often been considered as a separate group. There is, however, no academic agreement on which plays are the ‘last plays’ nor how, as a category, they should be termed. By briefly examining four of the most popular ways of classifying them (‘last plays’, ‘romances’, ‘late plays’ and ‘tragicomedies’), this article reviews difficulties of grouping and labelling the plays and examines the limitations of current critical approaches to late Shakespeare. It also functions as an overview of the distinctive features of these ‘last plays’.
Temperature‐sensitive fitness cost of insecticide resistance in Chinese populations of the diamondback moth Plutella xylostella
Authors: Zhang Lin Jie , Jing Yu Pu , Li Xiao Hui , Li Chang Wei , Bourguet Denis , Wu Gang
Published: March 2015

Alleles conferring a higher adaptive value in one environment may have a detrimental impact on fitness in another environment. Alleles conferring resistance to pesticides and drugs provide textbook examples of this trade‐off as, in addition to conferring resistance to these molecules, they frequently decrease fitness in pesticide/drug‐free environments. We show here that resistance to chlorpyrifos, an organophosphate (OP), in Chinese populations of the diamondback moth, Plutella xylostella, is conferred by two mutations of ace1 – the gene encoding the acetylcholinesterase enzyme targeted by OPs – affecting the amino acid sequence of the corresponding protein. These mutations were always linked, consistent with the segregation of a single resistance allele, ace1R, carrying both mutations, in the populations studied. We monitored the frequency of ace1R (by genotyping more than 20 000 adults) and the level of resistance (through bioassays on more than 50 000 individuals) over several generations. We found that the ace1R resistance allele was costly in the absence of insecticide and that this cost was likely recessive. This fitness costs involved a decrease in fecundity: females from resistant strains laid 20% fewer eggs, on average, than females from susceptible strains. Finally, we found that the fitness costs associated with the ace1R allele were greater at high temperatures. At least two life history traits were involved: longevity and fecundity. The relative longevity of resistant individuals was affected only at high temperatures and the relative fecundity of resistant females – which was already affected at temperatures optimal for development – decreased further at high temperatures. The implications of these findings for resistance management are discussed.
Phylogenetic distribution of symbiotic bacteria from Panamanian amphibians that inhibit growth of the lethal fungal pathogen Batrachochytrium dendrobatidis
Authors: Becker Matthew H. , Walke Jenifer B. , Murrill Lindsey , Woodhams Douglas C. , Reinert Laura K. , Rollins‐Smith Louise A. , Burzynski Elizabeth A. , Umile Thomas P. , Minbiole Kevin P. C. , Belden Lisa K.
Published: March 2015

The introduction of next‐generation sequencing has allowed for greater understanding of community composition of symbiotic microbial communities. However, determining the function of individual members of these microbial communities still largely relies on culture‐based methods. Here, we present results on the phylogenetic distribution of a defensive functional trait of cultured symbiotic bacteria associated with amphibians. Amphibians are host to a diverse community of cutaneous bacteria and some of these bacteria protect their host from the lethal fungal pathogen Batrachochytrium dendrobatidis (Bd) by secreting antifungal metabolites. We cultured over 450 bacterial isolates from the skins of Panamanian amphibian species and tested their interactions with Bd using an in vitro challenge assay. For a subset of isolates, we also completed coculture experiments and found that culturing isolates with Bd had no effect on inhibitory properties of the bacteria, but it significantly decreased metabolite secretion. In challenge assays, approximately 75% of the bacterial isolates inhibited Bd to some extent and these inhibitory isolates were widely distributed among all bacterial phyla. Although there was no clear phylogenetic signal of inhibition, three genera, Stenotrophomonas, Aeromonas and Pseudomonas, had a high proportion of inhibitory isolates (100%, 77% and 73%, respectively). Overall, our results demonstrate that antifungal properties are phylogenetically widespread in symbiotic microbial communities of Panamanian amphibians and that some functional redundancy for fungal inhibition occurs in these communities. We hope that these findings contribute to the discovery and development of probiotics for amphibians that can mitigate the threat of chytridiomycosis.
Reconstructing long‐term human impacts on plant communities: an ecological approach based on lake sediment DNA
Authors: Pansu Johan , Giguet‐Covex Charline , Ficetola Gentile Francesco , Gielly Ludovic , Boyer Frédéric , Zinger Lucie , Arnaud Fabien , Poulenard Jérôme , Taberlet Pierre , Choler Philippe
Published: March 2015

Paleoenvironmental studies are essential to understand biodiversity changes over long timescales and to assess the relative importance of anthropogenic and environmental factors. Sedimentary ancient DNA (sedaDNA) is an emerging tool in the field of paleoecology and has proven to be a complementary approach to the use of pollen and macroremains for investigating past community changes. SedaDNA‐based reconstructions of ancient environments often rely on indicator taxa or expert knowledge, but quantitative ecological analyses might provide more objective information. Here, we analysed sedaDNA to investigate plant community trajectories in the catchment of a high‐elevation lake in the Alps over the last 6400 years. We combined data on past and present plant species assemblages along with sedimentological and geochemical records to assess the relative impact of human activities through pastoralism, and abiotic factors (temperature and soil evolution). Over the last 6400 years, we identified significant variation in plant communities, mostly related to soil evolution and pastoral activities. An abrupt vegetational change corresponding to the establishment of an agropastoral landscape was detected during the Late Holocene, approximately 4500 years ago, with the replacement of mountain forests and tall‐herb communities by heathlands and grazed lands. Our results highlight the importance of anthropogenic activities in mountain areas for the long‐term evolution of local plant assemblages. SedaDNA data, associated with other paleoenvironmental proxies and present plant assemblages, appear to be a relevant tool for reconstruction of plant cover history. Their integration, in conjunction with classical tools, offers interesting perspectives for a better understanding of long‐term ecosystem dynamics under the influence of human‐induced and environmental drivers.
Differentially expressed genes match bill morphology and plumage despite largely undifferentiated genomes in a Holarctic songbird
Authors: Mason Nicholas A. , Taylor Scott A.
Published: March 2015

Understanding the patterns and processes that contribute to phenotypic diversity and speciation is a central goal of evolutionary biology. Recently, high‐throughput sequencing has provided unprecedented phylogenetic resolution in many lineages that have experienced rapid diversification. The Holarctic redpoll finches (Genus: Acanthis) provide an intriguing example of a recent, phenotypically diverse lineage; traditional sequencing and genotyping methods have failed to detect any genetic differences between currently recognized species, despite marked variation in plumage and morphology within the genus. We examined variation among 20 712 anonymous single nucleotide polymorphisms (SNPs) distributed throughout the redpoll genome in combination with 215 825 SNPs within the redpoll transcriptome, gene expression data and ecological niche modelling to evaluate genetic and ecological differentiation among currently recognized species. Expanding upon previous findings, we present evidence of (i) largely undifferentiated genomes among currently recognized species; (ii) substantial niche overlap across the North American Acanthis range; and (iii) a strong relationship between polygenic patterns of gene expression and continuous phenotypic variation within a sample of redpolls from North America. The patterns we report may be caused by high levels of ongoing gene flow between polymorphic populations, incomplete lineage sorting accompanying very recent or ongoing divergence, variation in cis‐regulatory elements, or phenotypic plasticity, but do not support a scenario of prolonged isolation and subsequent secondary contact. Together, these findings highlight ongoing theoretical and computational challenges presented by recent, rapid bouts of phenotypic diversification and provide new insight into the evolutionary dynamics of an intriguing, understudied non‐model system.
Navigating the labyrinth: a guide to sequence‐based, community ecology of arbuscular mycorrhizal fungi
Authors: Hart Miranda M. , Aleklett Kristin , Chagnon Pierre‐Luc , Egan Cameron , Ghignone Stefano , Helgason Thorunn , Lekberg Ylva , Öpik Maarja , Pickles Brian J. , Waller Lauren
Published: March 2015

Data generated from next generation sequencing (NGS) will soon comprise the majority of information about arbuscular mycorrhizal fungal (AMF) communities. Although these approaches give deeper insight, analysing NGS data involves decisions that can significantly affect results and conclusions. This is particularly true for AMF community studies, because much remains to be known about their basic biology and genetics.

During a workshop in 2013, representatives from seven research groups using NGS for AMF community ecology gathered to discuss common challenges and directions for future research. Our goal was to improve the quality and accessibility of NGS data for the AMF research community. Discussions spanned sampling design, sample preservation, sequencing, bioinformatics and data archiving.

With concrete examples we demonstrated how different approaches can significantly alter analysis outcomes. Failure to consider the consequences of these decisions may compound bias introduced at each step along the workflow.

The products of these discussions have been summarized in this paper in order to serve as a guide for any researcher undertaking NGS sequencing of AMF communities.
Dog and cat exposure and respective pet allergy in early childhood
Authors: Pyrhönen Kaisa , Näyhä Simo , Läärä Esa
Published: March 2015

Background

The association of dog and cat exposure in early childhood with the incidence of respective allergies has remained controversial. The aim of the study was to obtain population‐based evidence on the association of early exposure to dog or cat, or both, with dog and cat allergies.

Methods

The study population was identified from the nationwide population register comprising all children aged 1–4 yr (N = 4779) born between 2001 and 2005 and living in the province of South Karelia, Finland. Cross‐sectional questionnaire data on pet exposure in infancy and physician‐diagnosed pet allergies were obtained from 3024 participants and merged with longitudinally accumulated data on sIgE and skin prick tests indicating allergic sensitization abstracted from all patient records in the area.

Results

The adjusted relative incidence of positive test results (with 95% confidence intervals) was 2.69 (1.45‐5.02) for dog and 5.03 (2.47‐10.2) for cat allergens among children exposed to a respective pet alone compared with children without such exposure. The corresponding adjusted prevalence odds ratios for diagnosed dog and cat allergies were 1.75 (0.77‐3.79) and 5.13 (2.30‐11.4), respectively. The association between pet exposure and the incidence of positive test results was independent of parents' allergies.

Conclusions

Early exposure to dog and cat at home is associated with a higher incidence of respective pet allergy during the first four years of life. Further evidence from population‐based studies with longer follow‐up is required to justify any recommendation concerning early pet contacts with a view to preventing pet allergies later in life.
Key molecular processes of the diapause to post‐diapause quiescence transition in the alfalfa leafcutting bee Megachile rotundata identified by comparative transcriptome analysis
Authors: Yocum George D. , Rinehart Joseph P. , Horvath David P. , Kemp William P. , Bosch Jordi , Alroobi Rami , Salem Saeed
Published: March 2015

Insect diapause (dormancy) synchronizes an insect's life cycle to seasonal changes in the abiotic and biotic resources required for development and reproduction. Transcription analysis of diapause to post‐diapause quiescent transition in the alfalfa leafcutting bee Megachile rotundata Fabricius identifies 643 post‐diapause up‐regulated gene transcripts and 242 post‐diapause down‐regulated transcripts. The log2 fold change in gene expression levels ranges from −5 to 7. Transcripts from several pivotal diapause‐related processes, including chromatin remodelling, cellular signalling pathways, microRNA processing, anaerobic glycolysis, cell cycle arrest and neuroendocrine control, are identified as being differentially expressed during the diapause to post‐diapause transition. In conjunction with studies from other insect species, the data indicate that there are several common mechanisms of diapause control and maintenance.
Comparing the driving behaviours of individuals with frontotemporal lobar degeneration and those with Alzheimer's disease
Authors: Fujito Ryoko , Kamimura Naoto , Ikeda Manabu , Koyama Asuka , Shimodera Shinji , Morinobu Shigeru , Inoue Shimpei
Published: March 2015

Background

Assessing driving aptitude in dementia patients is critically important for both patient and public safety. However, there have been only a few reports on the driving behaviours and accident risk of patients with dementia, especially frontotemporal lobar degeneration (FTLD). Therefore, we compared the characteristics of driving behaviours in patients with FTLD and those with Alzheimer's disease (AD).

Methods

The subjects were 28 FTLD and 67 AD patients who visited the Department of Psychiatry, Kochi Medical School Hospital. We conducted semi‐structured interviews with their families and caregivers about traffic accident history and changes in patient driving behaviours after dementia onset and then compared the findings between the two groups.

Results

Overall changes in driving behaviours were reported in 89% (25/28) and 76% (51/67) of the FTLD and AD patients, respectively (P = 0.17). In the FTLD group, difficulty in judging inter‐vehicle distances, ignoring road signs and traffic signals, and distraction were reported in 50% (14/28), 61% (17/28), and 50% (14/28) of patients, respectively, and 75% (21/28) patients had caused a traffic accident after dementia onset. The risk of causing an accident was higher in the FTLD group than in the AD group (odds ratio = 10.4, 95% confidence interval = 3.7–29.1). In addition, the mean duration between dementia onset and a traffic accident was 1.35 years in the FTLD group compared with 3.0 years in the AD group (P < 0.01).

Conclusions

Patients with FTLD were more likely to show dangerous driving behaviours than those with AD, and the risk of causing a traffic accident may be higher in patients with FTLD from an early disease stage.
Forecasting Distributions of Inflation Rates: the Functional Auto-Regressive Approach
Authors: Chaudhuri Kausik , Kim Minjoo , Shin Yongcheol
Published: March 2015

In line with recent developments in the statistical analysis of functional data, we develop the semiparametric functional auto-regressive modelling approach to the density forecasting analysis of national rates of inflation by using sectoral inflation rates in the UK over the period January 1997–September 2013. The pseudo-out-of-sample forecasting evaluation and test results provide an overall support to superior performance of our proposed models over the aggregate auto-regressive models and their statistical validity. The fan chart analysis and the probability event forecasting exercise provide further support for our approach in a qualitative sense, revealing that the modified functional auto-regressive models can provide a complementary tool for generating the density forecast of inflation, and for analysing the performance of a central bank in achieving announced inflation targets. As inflation targeting monetary policies are usually set with recourse to the medium-term forecasts, our proposed work may provide policy makers with an invaluably enriched information set.
A pilot study of active rehabilitation for adolescents who are slow to recover from sport‐related concussion
Authors: Gagnon I. , Grilli L. , Friedman D. , Iverson G. L.
Published: March 2015

The purpose of this study was to examine the effectiveness of an active rehabilitation intervention for adolescents who are slow‐to‐recover after a sport‐related concussion. Ten adolescents (three girls and seven boys) seen at the Montreal Children's Hospital Concussion Clinic participated in this case series. Adolescents who were symptomatic more than 4 weeks after the injury were provided with an active rehabilitation intervention (M = 7.9 weeks following injury; range = 3.7 to 26.2 weeks). The rehabilitation program includes gradual, closely monitored light aerobic exercise, general coordination exercises, mental imagery, as well as reassurance, normalization of recovery, and stress/anxiety reduction strategies. The program continued until complete symptom resolution and readiness to begin stepwise return to activities. The primary outcome of the study was evolution of post‐concussion symptoms. Secondary outcomes included mood, energy, balance, and cognition. After the intervention, post‐concussion symptoms significantly decreased for the group of participants. They also had decreased fatigue and improved mood after 6 weeks of initiating the rehabilitation intervention. This case series shows that postconcussive symptoms and functioning in adolescents following sports‐related concussion can be improved after participation in an active rehabilitation intervention. The introduction of graded light intensity exercise in the post‐acute period following concussion is safe, feasible and appears to have a positive impact on adolescents' functioning.
A warning threshold for monitoring tuberculosis surveillance data: an alternative to hidden Markov model
Authors: Rafei Ali , Pasha Einollah , Jamshidi Orak Roohangiz
Published: March 2015

Objectives

Although hidden Markov model (HMM) is known as a powerful tool for the detection of epidemics based on the historical data, the frequent use of such a model poses some limitation especially when decision‐making is required for new observations. This study was aimed to address a warning threshold for monitoring the weekly incidences of tuberculosis as an alternative toHMM.

Methods

We extracted the weekly counts of newly diagnosed patients with sputum smear‐positive pulmonaryTBfrom 2005 to 2011 nationwide. To detect unexpected incidences of the disease, two approaches: Serfling andHMM, were applied in presence/absence of linear, seasonal and autoregressive components. Models were subsequently evaluated in terms of goodness of fit, and their results were compared in detection of the disease phases. Then, multiple hypothetical thresholds were constructed based on the estimate of models and the optimal one was revealed throughROCcurve analysis.

Results

Findings from both adjusted R‐square () and Bayesian information criterion (BIC) presented a higher goodness of fit for periodic autoregressiveHMM(BIC = −1323.6;) than other models. According toROCanalysis, better values for both Youden's index and area under curve (0. 96 and 0. 98 respectively) were obtained by the threshold based on the estimate of periodic autoregressive model.

Conclusions

As the optimal threshold presented in this study is simple in concept and has no limitation in practice, especially for monitoring new observations, we would recommend such a threshold to be used for monitoring ofTBincidence data in the surveillance system.
Analysis of High Speed Multistage Compressor Throughflow Using Spanwise Mixing
Authors: Dunham J.
Published: March 2015

Previous RAE papers have described the application of an S1-S2 flow calculation system, which does not model spanwise mixing, to the RAE C147 high speed research core compressor. Although this has proved a valuable design and analysis tool, it is shown by comparison with detailed interstage traverse measurements that it does not model accurately the radial profiles of stagnation temperature, pressure and flow angle as they develop through the C147. Published work utilising low speed compressor measurements has shown that the inclusion of spanwise mixing terms in throughflow analysis can improve the modelling of radial profiles while allowing more realistic loss models to be used. This paper describes the application of the Gallimore/Cumpsty spanwise mixing model to the C147 compressor. A brief description of the modelling is given, especially the simple annulus wall model not covered by the Gallimore/Cumpsty papers. Then a model of the C147 flow is constructed using simple endwall loss and deviation assumptions, together with other changes needed to represent what seems to be a hub stall. It is concluded that the mixing terms enable realistic radial distributions of loss and deviation to reproduce the observed flow. The temperature mixing terms are particularly important in a high speed unit because they prevent the erroneous accumulation of high temperatures near the walls.
Evaluation of Compressor Inlet Flow Conditioners
Authors: Haidari Ahmad , Hordendorf Thomas , Bartos John C.
Published: March 2015

Experimental investigations were conducted to determines: 1) the degradation of single stage centrifugal compressor performance due to induced inlet distortion and swirl, and 2) the subsequent performance recovery achievable by use of an upstream flow conditioner developed by VORTAB Incorporated. The compressor inlet flow velocity profile was distorted using out-of-plane double elbows and a specially designed swirl generator. The distorted flow was conditioned using the flow conditioner. Performance tests were conducted for baseline (no distortion), distorted flow, and conditioned flow. The results indicate that velocity profile distortion and swirl can strongly affect the compressor performance. It is additionally demonstrated that the profile correction and swirl elimination achieved with the flow conditioner recovers the compressor performance to its baseline level, with minimum device pressure loss.
Compressor Fault Identification From Overall Performance Data Based on Adaptive Stage Stacking
Authors: Mathioudakis K. , Stamatis A.
Published: March 2015

In the present paper a method for the identification of faulty stages in a multistage compressor is presented. The values of overall compressor parameters namely mass flow rate, pressure ratio and efficiency, at different operating points are the input data to the method. Employing these data the method gives the location and the number of faulty stages, as well as the amount of deviation from intact condition performance. It is shown that the kind of fault which has caused stage performance deterioration can be identified. Features of the method such as generality of applicability, input data requirement and reliability of the findings, are discussed.
Optimizing Automated Gas Turbine Fault Detection Using Statistical Pattern Recognition
Authors: Loukis E. , Mathioudakis K. , Papailiou K.
Published: March 2015

A method enabling the automated diagnosis of Gas Turbine Compressor blade faults, based on the principles of statistical pattern recognition is initially presented. The decision making is based on the derivation of spectral patterns from dynamic measurements data and then the calculation of discriminants with respect to reference spectral patterns of the faults while it takes into account their statistical properties. A method of optimizing the selection of discriminants using dynamic measurements data is also presented. A few scalar discriminants are derived, in such a way that the maximum available discrimination potential is exploited. In this way the success rate of automated decision making is further improved, while the need for intuitive discriminant selection is eliminated. The effectiveness of the proposed methods is demonstrated by application to data coming from an Industrial Gas Turbine while extension to other aspects of Fault Diagnosis is discussed.
Safety Aspects and Environmental Considerations for a 10 MW Cogeneration Heavy Duty Gas Turbine Burning Coke Oven Gas With 60% Hydrogen Content
Authors: Wolf Jürgen J. , Perkavec Marko A.
Published: March 2015

A customer of European Gas Turbines GmbH processes coal tar into chemical intermediate and final products. Continuous production throughout the year requires a peak electrical power of 10 megawatts and a continuous supply of approximately 30 tons per hour of superheated steam at a pressure of 41 bar. To cover these needs the customer chose a heavy duty gas turbine, type G3142J driving a generator. The exhaust gas from the gas turbine is fed to a waste heat boiler for steam production.
Hot Streaks and Phantom Cooling in a Turbine Rotor Passage: Part 2 — Combined Effects and Analytical Modelling
Authors: Rdback Richard J. , Dring Robert P.
Published: March 2015

This paper presents experimental documentation and analytical correlations demonstrating the effects of hot streak accumulation and phantom cooling on turbine rotor airfoil surface temperature. In particular, results are shown which quantify the impact of (1) a non-uniform temperature profile at the entrance of a turbine due to combustor-generated hot and cold streaks, and (2) cooling air discharged from the trailing edge of the upstream stator.

In Part 1 of this paper, experimental results are shown for a range of controlling variables to identify where streak accumulation and phantom cooling were most likely to be strongest. These variables include streak-to-free stream density ratio, streak injection location and coolant-to-free stream density and velocity ratios.

In Part 2 of this paper, experimental results are shown for the combined effects of hot streak and stator coolant on the adiabatic recovery temperature on the rotor. An analytical model is also developed to correlate the experimental results documented in Parts 1 and 2 of the paper.
Effects of Back-Pressure in a Lean Blowout Research Combustor
Authors: Sturgess G. J. , Heneghan S. P. , Vangsness M. D. , Ballal D. R. , Lesmerises A. L. , Shouse D.
Published: March 2015

Experimental information is presented on the effects of back-pressure on flame-holding in a gaseous fuel research combustor. Data for wall temperatures and static pressures are used to infer behavior of the major recirculation zones, as a supplement to some velocity and temperature profile measurements using LDV and CARS systems. Observations of flame behavior are also included. Lean blowout is improved by exit blockage, with strongest sensitivity at high combustor loadings. It is concluded that exit blockage exerts its influence through effects on the jet and recirculation zone shear layers.
Development of Gas Turbine Steam-Injection Water Recovery (SIWR) System
Authors: Nguyen H. B. , Otter A. den
Published: March 2015

This paper describes and discusses a “closed loop” steam injection water recovery (SIWR) cycle that was developed for steam injected gas turbine applications. This process is needed to support gas turbine steam injection especially in areas where water can not be wasted and complex water treatment is discouraged.

The development of the SIWR was initiated by NOVA in an effort to reduce environmental impact of operating gas turbines and to find suitable solutions for its expanding gas transmission system to meet future air emission restrictions. While turbine steam injection provides many benefits, it has not been considered for remote, less supported environments such as gas transmission applications due to its high water consumption. The SIWR process can alleviate this problem regardless of the amount of injection required.

The paper also covers conceptual designs of a prototype SIWR system on a small gas turbine unit. However, because of relatively high costs, it is generally believed that the system is more attractive to larger size turbines and especially when it is used in conjunction with co-generation or combined cycle applications.
A Survey of Platform Machinery in the North Sea
Authors: Overli Jan M. , Bakken Lars E.
Published: March 2015

This paper describes the historical data for gas turbine driven compressor and power generation packages built for the North Sea. The period surveyed spans from the start-up of Ekofisk to the present day. The paper covers 60 platforms in the Norwegian and UK sectors and a number in the Danish and Dutch sectors. The data gathered for each platform include details of gas turbines, compressors, gearboxes, couplings, tube and seat oil systems, skid arrangements, air filtration systems, exhaust systems and so forth. In total, approximately 320 electric power generating sets and 380 compressors are included, representing 5.5 million kW. The trend over the survey period is found from the recorded data, and a comparison is made between the Norwegian and UK sectors.
Influence of Blade Aerodynamic Loading on Efficiency of Radial-Inflow Turbines
Authors: Takamura T. , Nishiguchi F.
Published: March 2015

This paper describes the relation between turbine efficiency and rotor blade loading parameters. Tests were carried out on 12 kinds of rotors, which had the same inlet velocity triangle and meridional contour, but different blade numbers (8–11) and blade lengths. The momentum thickness and shape factor of the boundary layers obtained from the results of a quasi-three dimensional flow analysis were used as the rotor blade loading parameters. It was found that blade loading could be evaluated by the shape factor at the mean stream surface and that turbine efficiency was affected by the blade shape of the exducer.
Combined Closed Cycle (C3) Systems for Underwater Power Generation
Authors: Massardd Aristide , Arnulfi Gian Marid
Published: March 2015

In this paper three Closed Combined Cycle (C3) systems for underwater power generation are analyzed. In the first, the waste heat rejected by a Closed Brayton Cycle (CBC) is utilized to heat the working fluid of a bottoming Rankine Cycle; in the second, the heat of a primary energy loop fluid is used to heat both CBC and Rankine cycle working fluids; the third solution involves a Metal Rankine Cycle (MRC) combined with an Organic Rankine Cycle (ORC).

The significant benefits of the Closed Combined Cycle concepts, compared to the simple CBC system, such as efficiency increase and specific mass reduction, are presented and discussed. A comparison between the three C3 power plants is presented taking into account the technological maturity of all the plant components.
Condition Monitoring and Diagnostic Aspects of Gas Turbine Transient Response
Authors: Meher-Homji Cyrus B. , Bhargava Rakesh
Published: March 2015

Most engine health monitoring systems used for land based systems are based on steady state operation. Diagnostic analysis has traditionally been conducted under steady state conditions with on-line systems tending to concentrate on map based performance diagnostics using pattern analysis, fault matrices or expert systems. Transient analysis is a relatively a new technique and is being applied to some aeroengines. There is significant diagnostic content in turbine startup and shutdown data and in data obtained during power or speed changes. This data can be captured if an automatic on-line system is employed. This paper provides an overview of the use of both performance and mechanical transient analysis as a means to detect gas turbine problems. The paper covers the need for transient analysis and covers transient analysis techniques. Examples and a discussion of how transient analysis can be integrated within an existing on-line monitoring system is made.
A Liquid Pool Simulation on Droplet Combustion in a Swirl Flow
Authors: Hou Shuhn-Shyurng , Lin Ta-Hui
Published: March 2015

The influence of flow vorticity on droplet combustion and evaporation are experimentally simulated by using a burning liquid-pool system, and numerically investigated by considering a nonreactive, rotating, stagnation-point flow, respectively. The experiment involves measurements of flame temperature, flame position and evaporation rate of the liquid pool, observations of the recirculation zone and the soot layer, and identification of flame extinction. A finite-volume method is employed to numerically solve the corresponding transport equations. Calculated results show that in the vicinity of the liquid surface, both convection and diffusion transports are weakened by the flow vorticity resulting in the suppression of the evaporation strength of liquid; the recirculation zone can be identified and compared with experimental observation. For the steady burning of an ethanol pool in a swirl air jet, it is found that as the angular velocity increases, the diffusion flame shifts closer to the upper burner, has a larger flame thickness, experiences a smaller flame stretch but suffers from the reduction of mass diffusion of ethanol vapor to the flame. However, the evaporation rate of ethanol is usually decreased with increasing the angular velocity. In the flame extinction experiment, the critical volumetric oxygen concentration at extinction first decreases to a minimum value and then increases with angular velocity. It is generally concluded that the flow vorticity has a negative effect on both droplet combustion and evaporation.
Emissions and Stability Characteristics of Flameholders for Lean-Premixed Combustion
Authors: Lovett Jeffrey A. , Abuaf Nesim
Published: March 2015

An experimental study was conducted to determine the NOx emissions and flame stability associated with various flameholders used to support lean-premixed combustion of natural gas at gas turbine conditions. Data were obtained for velocities of 6 to 24 m/s, initial temperatures of 533 to 650 K, and pressures of 3.4 to 13.6 atm. Bluff-body, perforated-plate, and swirl-stabilized flameholders were tested and compared. The results confirm that NOx emissions at ultra-lean conditions scale with the flame temperature and are essentially independent of flameholder geometry for typical combustor residence times. The stability behavior, however, was strongly affected by flameholder type, illustrating the influence of fluid mechanics on flame stability. The flame stability was related also to the dynamics produced by combustion instability. A swirl-stabilized flameholder demonstrated the best stability characteristics at the expense of flameholder pressure drop.
The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump
Authors: Guinzburg A. , Brennen C. E. , Acosta A. J. , Caughey T. K.
Published: March 2015

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.
Innovative High Temperature Aircraft Engine Fuel Nozzle Design
Authors: Stickles R. W. , Dodds W. J. , Koblish T. R. , Sager J. , Clouser S.
Published: March 2015

The objective of the Innovative High Temperature Aircraft Engine Fuel Nozzle Program was to design and evaluate a nozzle capable of operating at a combustor inlet air temperature of 1600°F (1144°K) and a fuel temperature of 350°F (450°K). The nozzle was designed to meet the same performance requirements and fit within the size envelope of a current production F404 dual orifice fuel nozzle. The design approach was to use improved thermal protection and fuel passage geometry in combination with fuel passage surface treatment to minimize coking at these extreme fuel and air temperatures. Heat transfer models of several fuel injector concepts were used to optimize the thermal protection, while a series of sample tube coking tests were run to evaluate the effect of surface finish, coatings and tube material on the coking rate. Based on heat transfer analysis, additional air gaps, reduced fuel passage flow area and ceramic tip components reduced local fuel wetted wall temperatures by more than 200°F (110°K) when compared to a current production F404 fuel nozzle. Sample tube coking test results showed the importance of surface finish on the fuel coking rate. Therefore, a 1 micro-inch (.025 micron) roughness was specified for all fuel passage surfaces. A novel flow divider valve in the tip was also employed to reduce weight, allow room for additional thermal protection, and provide back pressure to reduce the risk of fuel vaporization. Phase II of this program will evaluate the fuel nozzle with a series of contaminated fuel and coking tests.
Coherent Anti-Stokes Raman Scattering (CARS) Thermometry in a Model Gas Turbine Can Combustor
Authors: Zhu J. Y. , Tsuruda T. , Sowa W. A. , Samuelsen G. S.
Published: March 2015

Non-intrusive, spatially resolved instantaneous temperature measurements are presented that were obtained from a reacting spray flame in a model gas turbine can combustor using coherent anti-Stokes Raman scattering (CARS) thermometry. The results show that CARS measurements agree with thermocouple measurements at the exit of the combustor. The liquid droplet induced dielectric breakdown is not an obstacle in applying CARS to reacting sprays. The CARS measured temperature field also indicates that there is a relatively cool region (T < 1000 K) near the nozzle tip. Reaction occurs in the region where large numbers of droplets are present and in the interface of the swirl-induced recirculation zone. This study demonstrates that CARS is a viable diagnostic tool for non-intrusive, instantaneous temperature measurements in practical spray flames.