bluuebunny/crossref_metadata_2025 huggingface dataset:
The dynamics of cereal cyst nematode infection differ between susceptible and resistant barley cultivars and lead to changes in (1,3;1,4)‐β‐glucan levels and HvCslF gene transcript abundance
Authors: Aditya Jessika , Lewis John , Shirley Neil J. , Tan Hwei‐Ting , Henderson Marilyn , Fincher Geoffrey B. , Burton Rachel A. , Mather Diane E. , Tucker Matthew R.
Published: March 2015

Heterodera avenae (cereal cyst nematode, CCN) infects the roots of barley (Hordeum vulgare) forming syncytial feeding sites. In resistant host plants, relatively few females develop to maturity. Little is known about the physiological and biochemical changes induced during CCN infection.

Responses to CCN infection were investigated in resistant (Rha2) and susceptible barley cultivars through histological, compositional and transcriptional analysis.

Two phases were identified that influence CCN viability, including feeding site establishment and subsequent cyst maturation. Syncytial development progressed faster in the resistant cultivar Chebec than in the susceptible cultivar Skiff, and was accompanied by changes in cell wall polysaccharide abundance, particularly (1,3;1,4)‐β‐glucan. Transcriptional profiling identified several glycosyl transferase genes, including CELLULOSE SYNTHASE‐LIKE F10 (HvCslF10), which may contribute to differences in polysaccharide abundance between resistant and susceptible cultivars.

In barley, Rha2‐mediated CCN resistance drives rapid deterioration of CCN feeding sites, specific changes in cell wall‐related transcript abundance and changes in cell wall composition. During H. avenae infection, (1,3;1,4)‐β‐glucan may influence CCN feeding site development by limiting solute flow, similar to (1,3)‐β‐glucan during dicot cyst nematode infections. Dynamic transcriptional changes in uncharacterized HvCslF genes, possibly involved in (1,3;1,4)‐β‐glucan synthesis, suggest a role for these genes in the CCN infection process.
Creating Effective Media Messaging for Rural Smoke‐free Policy
Authors: Riker Carol A. , Butler Karen M. , Ricks JaNelle M. , Record Rachael A. , Begley Kathy , Anderson Debra Gay , Hahn Ellen J.
Published: March 2015

Objectives

Objectives were to (1) explore perceived effectiveness of existing smoke‐free print advertisements in rural communities and (2) generate message content, characteristics, and media delivery channels that resonate with residents.

Design and Sample

Qualitative methods design. Thirty‐nine rural adults recruited by community partners.

Measures

Content analysis of findings from individuals in four focus groups who participated in general discussion and reviewed eight print ads related to secondhand smoke (SHS) and smoke‐free policy.

Results

Six content themes were identified: smoking/SHS dangers, worker health, analogies, economic impact, rights, and nostalgia. Seven message characteristics were recognized: short/to the point, large enough to read, graphic images, poignant stories, statistics/charts/graphs, message sender, and messages targeting different groups. Four media delivery channels were considered most effective: local media, technology, billboard messages, and print materials.

Conclusions

Seeking input from key informants is essential to reaching rural residents. Use of analogies in media messaging is a distinct contribution to the literature on effective smoke‐free campaigns. Other findings support previous studies of effective messaging and delivery channels. Further research is needed to examine effectiveness of themes related to message content in smoke‐free ads and delivery strategies. Effective media messaging can lead to policy change in rural communities to reduce exposure to SHS.
Relationship between dementia severity and behavioural and psychological symptoms in early‐onset Alzheimer's disease
Authors: Tanaka Hibiki , Hashimoto Mamoru , Fukuhara Ryuji , Ishikawa Tomohisa , Yatabe Yusuke , Kaneda Keiichiro , Yuuki Seiji , Honda Kazuki , Matsuzaki Shiho , Tsuyuguchi Atsuko , Hatada Yutaka , Ikeda Manabu
Published: March 2015

Background

The features of behavioural and psychological symptoms of dementia (BPSD) are influenced by dementia stage. In early‐onset Alzheimer's disease (EOAD), the association between BPSD and dementia stage remains unclear because of the difficulty of recruiting subjects with a wide range of disease severity. We used a combination of community‐based and hospital‐based approaches to investigate the relationship between dementia severity and BPSD in EOAD patients.

Methods

Sixty‐three consecutive EOAD outpatients and 29 EOAD patients from a community‐based survey were divided into three dementia severity groups according to the Clinical Dementia Rating scale (CDR): mild (CDR 0.5–1, n = 55), moderate (CDR 2, n = 17), and severe (CDR 3, n = 20). BPSD were rated using the Neuropsychiatric Inventory.

Results

Scores of the Neuropsychiatric Inventory subscales agitation, euphoria, apathy, disinhibition, irritability, and aberrant motor behaviour increased significantly with increased dementia severity. Hallucinations were greater in the moderate group than in the mild group. For delusions, depression, and anxiety, no significant differences were observed among the three severity groups.

Conclusions

The pattern of apathy, agitation, disinhibition, irritability, and aberrant motor behaviour worsening with severity progression in EOAD is similar to the pattern in late‐onset Alzheimer's disease. In contrast, hallucinations, depression, and anxiety showed different patterns in EOAD.
Restoring the endangered oyster mussel (Epioblasma capsaeformis) to the upper Clinch River, Virginia: an evaluation of population restoration techniques
Authors: Carey Caitlin S. , Jones Jess W. , Butler Robert S. , Hallerman Eric M.
Published: March 2015

From 2005 to 2011, the federally endangered freshwater mussel Epioblasma capsaeformis (oyster mussel) was reintroduced at three sites in the upper Clinch River, Virginia, using four release techniques. These release techniques were (1) translocation of adults (site 1, n = 1418), (2) release of laboratory‐propagated sub‐adults (site 1, n = 2851), (3) release of 8‐week‐old laboratory‐propagated juveniles (site 2, n = 9501), and (4) release of artificially infested host fishes (site 3, n = 1116 host fishes). These restoration efforts provided a unique research opportunity to compare the effectiveness of techniques used to reestablish populations of extirpated and declining species. We evaluated the relative success of these four population restoration approaches via monitoring at each release site (2011–2012) using systematic 0.25‐m2 quadrat sampling to estimate abundance and post‐release survival. Abundances of translocated adult and laboratory‐propagated sub‐adult E. capsaeformis at site 1 ranged 577–645 and 1678–1700 individuals, respectively, signifying successful settlement and high post‐release survival. Two untagged individuals (29.1 and 27.3 mm) were observed, indicating that recruitment is occurring at site 1. No E. capsaeformis were found at sites where 8‐week‐old laboratory‐propagated juveniles (site 2) and artificially infested host fishes (site 3) were released. Our results indicate that translocations of adults and releases of laboratory‐propagated sub‐adults were the most effective population restoration techniques for E. capsaeformis. We recommend that restoration efforts focus on the release of larger (>20 mm) individuals to accelerate augmenting and reintroducing populations and increase the probability for recovery of imperiled mussels.
Higher Moments and Prediction‐Based Estimation for the COGARCH(1,1) Model
Authors: Bibbona Enrico , Negri Ilia
Published: March 2015

COGARCH models are continuous time versions of the well‐known GARCH models of financial returns. The first aim of this paper is to show how the method of prediction‐based estimating functions can be applied to draw statistical inference from observations of a COGARCH(1,1) model if the higher‐order structure of the process is clarified. A second aim of the paper is to provide recursive expressions for the joint moments of any fixed order of the process. Asymptotic results are given, and a simulation study shows that the method of prediction‐based estimating function outperforms the other available estimation methods.
Science as a Learner and as a Teacher: Measuring Science Self‐Efficacy of Elementary Preservice Teachers
Authors: Knaggs Christine M. , Sondergeld Toni A.
Published: March 2015

Academic science achievement of U.S. students has raised concerns regarding our ability as a nation to compete in a global economy. Additionally, research has shown that many elementary teachers have weak science content backgrounds and had poor/negative experiences as students of science, resulting in a lack of confidence regarding teaching science. However, efforts to increase science self‐efficacy (SE) in preservice teachers can help to combat these issues. This study looked at a sample of preservice elementary teachers engaged in a semester‐long science content course, using Bandura's concept of SE as a conceptual framework. Our quantitative data showed significant increases in science SE on both subscales (personal efficacy and outcome expectancy). Our qualitative data showed that students communicated an increased sense of confidence with regard to the discipline of science. In addition, students reported learning science pedagogy through the instructor's modeling. Combining our findings resulted in several meta‐inferences, one of which showed students growing as both confident learners of science and teachers of science simultaneously. We created a construct new to the literature to describe this phenomenon: “teacher‐learner,” for students are both learning science and learning to teach science simultaneously through the content course experience, resulting in increased science SE.
Hd3a promotes lateral branching in rice
Authors: Tsuji Hiroyuki , Tachibana Chika , Tamaki Shojiro , Taoka Ken‐ichiro , Kyozuka Junko , Shimamoto Ko
Published: March 2015

Accumulating evidence indicates that the FLOWERING LOCUS T (FT) protein is the mobile floral signal known as florigen. A rice FT homolog, Heading date 3a (Hd3a), is transported from the phloem to shoot apical cells, where it interacts with 14–3–3 proteins and transcription factor OsFD1 to form a florigen activation complex (FAC) that activates a rice homolog of the floral identity gene APETALA1. Recent studies showed that florigen has roles in plant development beyond flowering; however, the exact nature of these roles is not well understood. It is not clear whether FT is transported to organs outside the shoot apex, and whether FAC formation is required for processes other than flowering. We show here that the Hd3a protein accumulates in axillary meristems to promote branching, and that FAC formation is required. Analysis of transgenic plants revealed that Hd3a promotes branching through lateral bud outgrowth. Hd3a protein produced in the phloem reached the axillary meristem in the lateral bud, and its transport was required for promotion of branching. Moreover, mutant Hd3a proteins defective in FAC formation but competent with respect to transport did not promote branching. Finally, we show that Hd3a promotes branching independently from strigolactone and FC1, a transcription factor that inhibits branching in rice. Together, these results suggest that Hd3a functions as a mobile signal for branching in rice.
A straightforward and reliable method for bacterial in planta transcriptomics: application to the Dickeya dadantii/Arabidopsis thaliana pathosystem
Authors: Chapelle Emilie , Alunni Benoît , Malfatti Pierrette , Solier Lucie , Pédron Jacques , Kraepiel Yvan , Van Gijsegem Frédérique
Published: March 2015

Transcriptome analysis of bacterial pathogens is a powerful approach to identify and study the expression patterns of genes during host infection. However, analysis of the early stages of bacterial virulence at the genome scale is lacking with respect to understanding of plant–pathogen interactions and diseases, especially during foliar infection. This is mainly due to both the low ratio of bacterial cells to plant material at the beginning of infection, and the high contamination by chloroplastic material. Here we describe a reliable and straightforward method for bacterial cell purification from infected leaf tissues, effective even if only a small amount of bacteria is present relative to plant material. The efficiency of this method for transcriptomic analysis was validated by analysing the expression profiles of the phytopathogenic enterobacterium Dickeya dadantii, a soft rot disease‐causing agent, during the first hours of infection of the model host plant Arabidopsis thaliana. Transcriptome profiles of epiphytic bacteria and bacteria colonizing host tissues were compared, allowing identification of approximately 100 differentially expressed genes. Requiring no specific equipment, cost‐friendly and easily transferable to other pathosystems, this method should be of great interest for many other plant–bacteria interaction studies.
Inactivation of viruses in platelet and plasma products using a riboflavin‐and‐UV–based photochemical treatment
Authors: Keil Shawn D. , Bengrine Abderrahmane , Bowen Richard , Marschner Susanne , Hovenga Nick , Rouse Lindsay , Gilmour Denise , Duverlie Gilles , Goodrich Raymond P.
Published: March 2015

BACKGROUND

Multilayered blood safety programs reduce the risk of transfusion‐transmitted diseases; however, there remains a risk of window period transmission of screened viruses and transmission of unscreened and emerging viruses from asymptomatic donors. To reduce this risk, a riboflavin‐and‐UV‐light–based pathogen reduction process was evaluated against eight viral agents.

STUDY DESIGN AND METHODS

Riboflavin and UV light was evaluated against the following eight viral agents: encephalomyocarditis virus (EMC), hepatitis A virus (HAV), hepatitis C virus (HCV), influenza A (FLUAV), La Crosse virus (LACV), pseudorabies virus (PRV), sindbis virus (SINV), and vesicular stomatitis virus (VSV). Before treatment, a sample was removed to determine the product's initial viral load. After treatment the product's viral load was reevaluated and the log reduction was calculated.

RESULTS

Virus reduction after treatment with riboflavin and UV light is equivalent in platelet (PLT) and plasma units, as demonstrated by a 3.2‐log reduction of EMC in plasma, PLTs, and PLT additive solution containing 35% plasma. Additionally, the following viral reductions values were observed: HAV 1.8 log, HCV at least 4.1 log, FLUAV at least 5.0 log, LACV at least 3.5 log, PRV 2.5 log, SINV 3.2 log, and VSV at least 6.3 log.

CONCLUSIONS

The results observed in this study suggest that treating PLT and plasma products with a riboflavin‐and‐UV‐light–based pathogen reduction process could potentially eliminate window period transmission of screened viruses and greatly reduce the risk of transfusion transmission of unscreened viruses.
Hypotensive transfusion reactions in the era of prestorage leukoreduction
Authors: Pagano Monica B. , Ness Paul M. , Chajewski Olga S. , King Karen E. , Wu Yanyun , Tobian Aaron A.R.
Published: March 2015

BACKGROUND

Clinical characteristics of hypotensive transfusion reactions (HyTRs) have not been evaluated in the context of universal prestorage leukoreduction.

STUDY DESIGN AND METHODS

A retrospective review of medical records of patients with HyTRs during the years 2011 and 2012 was performed at two academic medical institutions.

RESULTS

Thirty‐five patients with 35 HyTRs were identified, with an incidence of 1.33 per 10,000 transfusions. Red blood cells (RBCs) were implicated in 21 (60.0%) reactions and platelets (PLTs) and plasma (PL) in 11 (31.4%) and three (8.6%), respectively. The HyTR rate per blood component was 0.019% for PLTs, 0.015% for RBCs, and 0.006% for PL. Mean patient age was 65 years (range, 2 months‐87 years), five (14.3%) were pediatric (<18 years), and 20 (57.1%) were male. The most frequent clinical settings associated with HyTRs were cardiac surgery (n = 13; 37.1%), hematology‐oncology diseases (n = 11; 31.4%), and general surgery (n = 7; 20.0%). Extracorporeal circuits were used within 24 hours before the reaction in 16 patients (45.7%), including nine patients on cardiopulmonary bypass, four on dialysis or continuous venous‐venous hemodialysis, and three on extracorporeal membrane oxygenation. Four patients (11.4%) received an angiotensin‐converting enzyme inhibitor within 24 hours before the HyTR. Seventeen patients (48.6%) responded to stopping the transfusion and supportive treatment. Thirteen patients (37.1%) had severe reactions. No HyTR resulted in death.

CONCLUSION

In the absence of bedside leukoreduction filters, several medical situations are associated with HyTRs. The pathophysiology of HyTRs is yet to be defined. The US hemovigilance system allows for standardization of transfusion reactions, which facilitates their classification and study.
Conceptual Design of a Centrifugal Compressor Including Consideration of the Effect of Inlet Prewhirl
Authors: Whitfield A.
Published: March 2015

A non-dimensional impeller design procedure, including the effect of inlet prewhirl, is described. It is shown that the basic non-dimensional parameters commonly used to present the performance of compressors also provide an adequate basis from which a conceptual design procedure can be developed. The adoption of composite non-dimensional groupings such as specific speed and specific diameter are unnecessary. The design procedure is developed non-dimensionally to provide the appropriate impeller geometry as a ratio of the outer radius, and inlet and discharge blade angles. A compressor design for a pressure ratio of 4 to 1 is used to provide an illustrative example.
Stage Efficiency Effects of Vaneless Diffuser Wall Contours
Authors: Wulf James B.
Published: March 2015

The effects of vaneless diffuser wall contour were investigated in a systematic series of laboratory tests. The test stage was investigated in an integral gear compressor operating on a laboratory test stand. The compressor was driven with a variable speed 1500 HP motor. A computer controlled data acquisition and reduction system was used. The 27.94 cm diameter test impeller was operated with vaneless diffusers and volute collectors.

Beginning with a substantially parallel wall vaneless diffuser, peak stage adiabatic total to total efficiency was improved from 80.2% to 87.5% and operating range was extended.

The interaction between the impeller, diffuser and volute was studied through detailed analysis of intra-stage static pressure data using a jet wake model. The results of data analysis show that wall contour had a small influence on impeller efficiency and that most of the stage performance improvement resulted from improved recovery in the vaneless diffuser.
Experimental Results on a Rotatable Low Solidity Vaned Diffuser
Authors: Sorokes J. M. , Welch J. P.
Published: March 2015

This paper reviews test results from a rotatable low solidity vaned diffuser (RLSD). The device was installed in a single stage test vehicle consisting of a pseudo-return channel inlet, a subsonic centrifugal impeller (approx. 2:1 pressure ratio), the rotatable diffuser, a return channel and a dump collector. Static taps, total pressure probes, and thermocouples were located in critical areas throughout the stage. Manual traverse probes measured the pressure and angle profiles at RLSD leading and trailing edges. Results for various stagger angles, leading edge radius ratios, etc. are presented in terms of pressure recovery (Cp) and loss coefficient (LC). Comments are made regarding the applicability of the RLSD in production units.
Active Control of Complex Physical Systems: An Overview
Authors: Hansen Robert J. , Hendricks Eric W.
Published: March 2015

Active control of complex systems imposes unique requirements for physical models and feedback control strategies. Physical models which are adequate to predict the influence of actuators must be coupled with feedback control approaches suitable for use when system characteristics are incompletely specified a priori and change with time. The present paper describes laboratory scale experiments in which turbomachinery surge and stall and combustion instabilities are successfully attenuated by active means. Work which has been conducted in parallel to develop improved models and control strategies to realize fault tolerant active control of such systems in the full scale operational environment is also discussed.
100 MW Combined Cycle Achieves 7000 BTU/KWH Heat Rate at JFK International Airport
Authors: Kolp Donald A. , Roberts Richard , Kim Soo Young
Published: March 2015

In early 1994 a 100 MW LM6000 combined cycle cogeneration plant will begin operation at New York City’s John F. Kennedy International Airport. Thanks to the extremely high simple cycle efficiency of the LM6000 gas turbine (8200 BTU/KWH, 8650 kJ/KWH-LHV dry) and a sophisticated three-pressure steam generating system, a heat rate below 7000 BTU/KWH-LHV (7380 kJ/KWH-LHV) is expected when operating in combined cycle mode. The dual-spool LM6000 achieves its efficiency by means of a 30:1 compression ratio. 2100 F. (1149 C.) firing temperatures and the direct coupling of the low compressor/turbine rotor to the electric generator. The efficiency of the heat recovery steam generator results from the use of three economizers, three evaporators and two superheaters combined with a patented feedwater heating system which yields a 245 F. (118 C.) exhaust stack temperature.

Operating flexibility is essential in this application. While the dual-fueled plant is designed for pure combined cycle operation, most of the time it will operate in a cogeneration mode — producing up to 250 × 106 BTU/HR (264 × 106 kJ/HR) of steam for heating in the winter and 7000 (24,618 KW) tons of chilling for air conditioning airport terminals in the summer. The waste heat boilers are designed to be supplementary fired on gas fuel when the airport requires the 110 MW maximum capacity of the plant simultaneously with the maximum thermal load of 250 × 106 BTU/HR (264 × 106 kJ/HR).

NOx emissions are controlled with a combination of water injection in the turbine combustors and a dual-function catalyst SCR/CO converter. CO is controlled by means of the converter. Combined gas turbine and duct burner NOx is maintained below 9.0 PPMV dry (@ 15% O2) and CO below 1.5 PPH (0.68 KG/HR) dry (@ 15% O2) when operating on gas fuel.

Cycle details, equipment selection and operation as well as the plant economics provide a useful insight into the benefits of these recent developments in gas turbine and heat recovery combined cycle cogeneration technology.
A Model and State-Space Controllers for an Intercooled, Regenerated (ICR) Gas Turbine Engine
Authors: Watts J. W. , Dwan T. E. , Garman R. W.
Published: March 2015

A two-and-one-half spool gas turbine engine was modeled using the Advanced Computer Simulation Language (ACSL), a high level simulation environment based on FORTRAN. A possible future high efficiency engine for powering naval ships is an intercooled, regenerated (ICR) gas turbine engine and these features were incorporated into the model. Utilizing sophisticated instructions available in ACSL linear state-space models for this engine were obtained. A high level engineering computational language, MATLAB, was employed to exercise these models to obtain optimal feedback controllers characterized by the following methods: (1) state feedback; (2) linear quadratic regulator (LQR) theory; and (3) polygonal search. The methods were compared by examining the transient curves for a fixed off-load, and on-load profile.
An Investigation on the Artificial Viscosity in the Transonic Stream Function Formulation
Authors: Xu J. Z. , Du J. Y. , Shen H. , Ge M. C.
Published: March 2015

The artificial density method applied widely in the transonic potential and stream function calculations is investigated theoretically. The analysis shows that the method is no longer valid in the stream function formulation, and a correct expression for the artificial viscosity in the stream function method is derived. The numerical examples show that the computed range of Mach number by the present transonic stream function formulation is extended and the shock location is more clase to the experimental result.
Development of a Knowledge Based Advisory System Based on Vibration of a Peaking Gas Turbine
Authors: Baldwin Richard M. , Smalley Anthony J. , Harris Ralph E. , Quentin George H.
Published: March 2015

This paper describes the process of knowledge development and interpretation for a particular model of power generation combustion turbine and generator. The knowledge derives from three sources: fundamental understanding of rotordynamics; the experience of experts in troubleshooting this particular turbine; and in-depth analysis of vibration data acquired during every start-up and run of several examples. The data acquisition system is operated via modem from any phone tine to provide operational data for review.

The knowledge is to be applied in two ways. A Post Trip Analysis will provide the operator with advice on what to do when the unit trips, based upon the data obtained during the tripped run and previously acquired characteristics. The Post Trip Analysis will have knowledge which, when compared with the acquired data factors about vibration, and historical characteristics of the specific machine or the fleet, will give a recommended action. This application is designed to be available moments after the trip has occurred.

The second application of knowledge is for health assessment. A software module will automatically analyze each day’s data when the file is completed. The volume of data is reduced to a smaller, very descriptive set of data which is saved and compared with previous runs. These analyses are to be performed at the two critical speeds of the turbine and generator, as well as the normal running speed. One planned test for health assessment is to seek deviations: characteristics which fall outside the statistically normal range for the unit in question; characteristics which fall outside the desirable range based on expert opinion; and distinct unexplained changes during a run.

The paper illustrates the development and application of the knowledge base.
Flow Pattern and Heat Transfer in a Closed Rotating Annulus
Authors: Bohn D. , Dibelius G. H. , Deuker E. , Emunds R.
Published: March 2015

The prediction of the temperature distribution in a gas turbine rotor containing gas filled closed cavities, for example in between two discs, has to account for the heat transfer conditions encountered inside these cavities. In an entirely closed annulus no forced convection is present, but a strong natural convection flow occurs induced by a non-uniform density distribution in the centrifugal force field.

A computer code has been developed and applied to a rotating annulus with square cross section as a base case. A co-axial heat flux from one side wall to the other was modelled assuming the temperatures at this walls being different but uniformly distributed, while both the outer and inner cylindrical surfaces were assumed to be adiabatic.

The code was first verified for the annulus approaching the plane square cavity in the gravitational field, i.e. the ratio of the radius r over the distance h between outer and inner cylindrical wall was set very large. The results obtained agree with De Vahl Davis’ benchmark solution. By reducing the inner radius to zero, the results could be compared with Chew’s computation of a closed rotating cylinder, and again good agreement was found.

Parametric studies were carried out varying the Grashof number Gr, the rotational Reynolds number Re and the r/h-ratio, i.e. the curvature of the annulus. A decrease of this ratio at constant Gr and Re number results in a decrease of heat transfer due to the Coriolis forces attenuating the relative gas velocity. The same effect can be obtained by increasing the Re number with the h/r-ratio and the Gr number being constant.

By inserting radial walls into the cavity the influence of the Coriolis forces is reduced resulting in an increase of heat transfer.
Aerodynamic Design of Turbomachinery Blading in Three-Dimensional Flow: An Application to Radial Inflow Turbines
Authors: Yang Y. L. , Tan C. S. , Hawthorne W. R.
Published: March 2015

A computational method, based on a theory for turbomachinery blading design in three-dimensional inviscid flow, is applied to a parametric design study of a radial inflow turbine wheel. As the method requires the specification of swirl distribution, a technique for its smooth generation within the blade region is proposed. Excellent agreements have been obtained between the computed results from this design method and those from direct Euler computations, demonstrating the correspondence and consistency between the two. The computed results indicate the sensitivity of the pressure distribution to a lean in the stacking axis and a minor alteration in the hub/shroud profiles. Analysis based on Navier-Stokes solver shows no breakdown of flow within the designed blade passage and agreement with that from design calculation; thus the flow in the designed turbine rotor closely approximates that of an inviscid one. These calculations illustrates the use of a design method coupled to an analysis tool for establishing guidelines and criteria for designing turbomachinery blading.
Extending the Fatigue Life of Aircraft Engine Components by Hole Cold Expansion Technology
Authors: Rufin Antonio C.
Published: March 2015

The split-sleeve cold expansion process has been used successfully for over 20 years to extend the fatigue life of holes in aircraft structures. Cold expansion technology can also be applied to enhance engine low-cycle fatigue (LCF) performance in both production and repair applications. Specific test data are presented showing that fatigue life extension can be attained by cold expansion of holes in a wide range of situations (including non-round hole geometries and low edge margins), and in components subjected to high operating temperatures. A cold expanded bushing system is compared to standard shrink-fit bushing installations. Finally, two case studies are used to illustrate the application of cold expansion to full-scale engine components.
Fault Signatures Obtained From Fault Implant Tests on an F404 Engine
Authors: Eustace Richard W. , Woodyatt Bruce A. , Merrington Graeme L. , Runacres Tony A.
Published: March 2015

The fault diagnostic process for gas turbine engines can be improved if data acquired by an on-board engine monitoring system (EMS) are utilised effectively. In the commercial transport field, techniques are available to extract engine condition assessment information from steady-state EMS data. In a military environment, steady-state data are not always available, and therefore it is desirable to extract at least some of the information from transient data, such as during take-off. Fault signatures are presented for an F404 engine based on fault implant tests in a sea-level-static (SLS) test-cell. A comparison is then made between the fault coverage capabilities of fault diagnostic techniques based on the use of steady-state engine data with those using transient data. The important conclusions to emerge from this work are that for the range of faults examined, not only is there similar fault information contained within the transient data but the faults can be detected with increased sensitivity using these data.
The Effect of Compressor Rotor Tip Crops on Turboshaft Engine Performance
Authors: Frith Peter C.
Published: March 2015

The results from an experimental study into the effect of compressor rotor tip clearance changes on the steady-state performance and stability margins of a free-power turbine turboshaft engine are presented and discussed. This work was directed at the development of methods to diagnose engine condition from gas path measurements. It was found that the normal production suite of engine instrumentation was able to measure the deterioration in engine performance due to the implanted compressor degradation and the resultant deviations in the measured parameters from their respective nominal baselines do provide useful indicators of engine condition.
A Study of Stall in a Low Hub/Tip Ratio Fan
Authors: Soundranayagam M. , Elder R. L.
Published: March 2015

An investigation has been carried out in order to define the process of rotating stall inception in a low speed, low hub-tip ratio fan. Based on elementary cascade analysis, the fan would be expected to stall from the root, however, considerable experimental evidence indicates that tip stall is more frequently incurred. Although the analysis has been undertaken for a specific fan it is considerd to be representative of a broad range of machines. The analysis has involved two primary considerations, first the effect of streamtube contraction which has been studied theoretically and secondly real flow effects (those not contained in the theoretical model) which have been studied experimentally.

The study of streamtube contraction indicates that the root rematches to a more stable operating point thus alleviating some of the problems in that region. The experimental investigation was undertaken on an isolated rotor, with successive build modifications to increase the likelihood of rotating stall inception at the root. It was apparent that real fluid effects tended to steepen the root pressure rise characteristic, thus enhancing the stability in that region. The performance of the fan at the tip tended to be poor providing a pressure characteristic with a lower negative gradient than anticipated indicating less stability than simple flow models would suggest. Hot wire flow mapping at the rotor exit supported the overall conclusion that the rotor showed a strong reluctance to stall at the root apparently due to “centrifuging” of the boundary layer towards the tip.
Aerodynamic Design of Pivotable Nozzle Vanes for Radial-Inflow Turbines
Authors: Schölch M.
Published: March 2015

In order to improve the efficiency of a radial inflow turbine new inlet guide vanes were developed. The design was the result of iteratively changing the outline of the blade contour and subsequent aerodynamic investigation of the new cascade generated. The procedure consists of four steps:

– Conformal transformation of the radial cascade into a straight cascade

– Determination of the incompressible inviscid velocity distribution on the blades of the straight cascade by means of a potential flow analysis

– Retransformation of velocity distribution and blade geometry into the radial plane

– Application of a boundary layer program to the velocity distribution on the contour of the profile in the radial plane

The efficiency of the turbine was measured in operation with the original and the new guide vanes at different pressure ratios and nozzle positions. The total–to–static efficiency of the turbine increased in all measured points, in some points by two percent.
Comparisons of Recuperator Flow Distributions of an Intercooled-Recuperative Marine Gas Turbine
Authors: Kiang Robert L. , Buyer Janet L. , Uhlig Robert A.
Published: March 2015

An intercooled-recuperative Brayton cycle is known to have a significantly higher thermal efficiency than a simple Brayton cycle. The success of an ICR gas turbine engine, however, depends in part on the performance of the recuperator. A uniform flow leading into the recuperator is usually assumed in the recuperator design. The complex geometry of the exhaust diffuser, which is located upstream of the recuperator, suggests that the flow may not be uniform. This study is an experimental investigation into the uniformity of flow through two specific exhaust diffuser/recuperator designs. It is found that the flow is nonuniform, but the nonuniformity is mostly invariant with respect to the exhaust gas flow rate, or equivalently, the engine power level between 25% and 50% full power.
Influence of Flow Conditions on Deposits From Heated Hydrocarbon Fuels
Authors: Chin J. S. , Lefebvre A. H.
Published: March 2015

The thermal stability characteristics of two liquid hydrocarbon fuels are examined using a single-pass system whereby the fuel under test flows only once through a heated tube which is maintained at constant temperature throughout a test duration of six hours. Deposition rates on the tube walls are measured by weighing the tube before and after each test.

The experimental data are used to derive empirical equations for predicting the effects on deposition rates of variation in fuel temperature, wall temperature, and Reynolds number. It is found that deposition rates are enhanced by increases in fuel temperature, wall temperature and flow velocity, and by reductions in tube diameter. Pressure has no effect on deposition rates provided it is high enough to prevent fuel boiling.
Application of a Sulphur-Doped Alkane System to the Study of Thermal Oxidation of Jet Fuels
Authors: Jones E. G. , Balster W. J.
Published: March 2015

A system of diphenyldisulphide in hexadecane was selected for modeling the formation of insolubles in jet fuels. The system was stressed in a series of flask tests at 185°C under fixed oxygen flow. The quantity of filterable insoluble solids and insoluble gums was measured as a function of time and found to increase linearly following an initial induction period. Rates associated with the linear growth were evaluated for a series of oxygen flows to obtain the oxygen dependence of insoluble-solid and insoluble-gum formation. Results indicate that insoluble gums and insoluble solids are formed by independent processes. Bulk and surface rates show a linear correlation, indicating that the precursors to insolubles formed in the bulk and those formed on the surface are similar.
Structure of a Hollow-Cone Spray With and Without Combustion
Authors: Chehroudi B. , Ghaffarpour M.
Published: March 2015

A hollow-cone spray with a nominal cone angle of 30 degrees from a pressure-swirl fuel atomizer was used in a swirl-stabilized combustor. The combustor is circular in cross section, with a swirl plate and fuel nozzle axis coinciding with the axes of the chamber. kerosene is injected upward inside the chamber from the fuel nozzle. Separate swirl and dilution air flows are distributed into the chamber that pass through honeycomb flow straighteners and screens. A calculated swirl number of 1.5 is generated with the design swirl plate exit air velocity of 30 degrees with respect to the chamber axis. Effects of swirl and dilution air flow rates on the shape and stability of the flame are investigated. A Phase Doppler Particle Analyzer (PDPA) is used to measure drop size, mean and rms values of axial drop velocity, fuel volume flux, drop velocity and size distributions, and size-classified drop velocity profiles for two cases of with and without combustion and at six different axial locations from the nozzle. For the no-combustion case all air and fuel flow rates were kept at the same values as the combusting spray condition. Results for mean axial drop velocity profiles indicate widening of the spray, with slight increase in the magnitudes of the peak drop velocities due to combustion. Root mean square (RMS) values of drop velocity fluctuations decrease due to a combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter mean diameter (SMD) radial profiles at all axial locations increase with combustion due to preferential burning of small drops. Fuel volume flux profiles indicate negligible drop vaporization and/or burning up to a distance of 25mm from the nozzle. Velocity number distributions at different radial points for without combustion at an axial distance of 55mm from the atomizer are symmetric in shape only close to the peak of the mean drop velocity and show a bimodal shape around the maximum mean drop axial velocity gradient. Corresponding number distributions for the combustion case are fairly symmetric and quite different in behavior at all radial positions. Size-classified drop velocity profiles are also plotted and discussed.
The Combined Closed Form–Perturbation Approach to the Analysis of Mistuned Bladed Disks
Authors: Mignolet Marc P. , Lin Chung-Chih
Published: March 2015

A two-step method is presented for the determination of reliable approximations of the probability density function of the forced response of a randomly mistuned bladed disk. Under the assumption of linearity, an integral representation of the probability density function of the blade amplitude is first derived. Then, deterministic perturbation techniques are employed to produce simple approximations of this function. The adequacy of the method is demonstrated by comparing several approximate solutions with simulation results.
Three-Dimensional Gas Turbine Combustor Emissions Modeling
Authors: Rizk N. K. , Mongia H. C.
Published: March 2015

An emission model that combines the analytical capabilities of 3-D combustor performance codes with mathematical expressions based on detailed chemical kinetic scheme is formulated. The expressions provide the trends of formation and/or the consumption of NOx, CO, and UHC in various regions of the combustor utilizing the details of the flow and combustion characteristics given by the 3-D analysis. By this means, the optimization of the combustor design to minimize pollutant formation and maintain satisfactory stability and performance could be achieved. The developed model was used to calculate the emissions produced by several engine combustors that varied significantly in design and concept, and operated on both conventional and high density fuels. The calculated emissions agreed well with the measurements. The model also provided insight into the regions in the combustor where excessive emissions were formed, and helped to understand the influence of the combustor details and air admission arrangement on reaction rates and pollutant concentrations.
Effects of Variable Liquid Properties on Multicomponent Droplet Vaporization
Authors: Kneer R. , Schneider M. , Noll B. , Wittig S.
Published: March 2015

A multicomponent droplet vaporization model, the Diffusion-Limit Model, is modified to account for the variation of liquid properties due to large temperature gradients as well as considerable concentration gradients within the droplet.

The effects on the vaporization behavior are analysed for an isolated bicomponent droplet consisting of heptane and dodecane. The results are presented for both moderate and high gas temperatures excluding combustion.

During the vaporization process the liquid phase properties vary considerably. For example, the Lewis number changes approximately one order of magnitude. The mass ratio of the liquid components seems to be rather sensitive to the variation of thermophysical property values, especially during the second half of the droplet lifetime, where about 50% of the droplet mass will still evaporate. The gas phase behavior is less affected by the use of constant liquid properties.

For both gas temperature levels tested it was found that single component models cannot describe satisfactorily the whole vaporization process of multicomponent droplets. With regard to ignition the sharp rise of the vapor concentration in the beginning of the droplet vaporization is important. This behavior is caused by the more volatile component and cannot be achieved by the single component substitute.
The Combustion of Droplets Within Gas Turbine Combustors Some Recent Observations on Combustion Efficiency
Authors: Odgers J. , Kretschmer D. , Pearce G. F.
Published: March 2015

For many years investigators studying the combustion behaviour within gas turbines have presumed droplet size to play a very important role in defining combustion efficiency. Recently a very large number of experiments have been conducted jointly by Laval University and the Aeronautical Research Laboratory in Melbourne. In the course of these investigations, over a wide range of operating conditions, a single combustor has been investigated using three different Simplex atomisers at each of the conditions for three fuels. In addition, the same combustor has been used to investigate a very wide range of fuels (87) at ambient inlet conditions.

The measured combustion efficiencies show no measurable effects due to droplet size, although volatility effects have been noted (measured as TAV). It is thought that these effects are reflected in terms of a Transfer Number and related to diffusional phenomena, rather than evaporative phenomena.

A great number of experimental data are reviewed, and in addition to showing the absence of effects of droplets, a small section deals with the precision of experimental values of combustion efficiency and how it might influence models predicting combustion efficiency, especially with respect to possible future pollution requirements.
Three Component LDV Velocity Measurements in a Can Type Research Combustor for CFD Validation: Part 1 — Isothermal
Authors: Ahmed Saad A. , Rose Alan , Nejad Abdollah S.
Published: March 2015

A two-component fibre optic LDV system has been employed to measure three mean velocity components and five Reynolds Stress components in a confined, isothermal strongly swirling flowfield. The primary objective is to provide complete benchmark data for comparisons with numerical predictions based on practical models for turbulent swirling flows and thereby guide the development of such models. Results of initial modelling work are presented and even at this early stage in the programme, the superiority of the Reynolds Stress modelling approach is clearly illustrated through comparisons with the results from experiment and a typical k–ε model. Measurements show the radial velocity component (close to the swirler exit) to be of the same magnitude as the axial and swirl components. Velocity measurements obtained close to the combustor wall should be treated with caution as these were most affected by signal noise as a result of internal wall reflections.
Corrosion Resistance of INCONEL Alloy 617 in Simulated Gas Turbine Environments
Authors: Ganesan P. , Smith G. D. , Yates D. H.
Published: March 2015

It is known that the efficiency of a gas turbine engine can be improved substantially by increasing the operating temperature. However, increasing the temperature puts a tremendous demand on the performance of materials of construction such as the combustion chamber, transition ducts etc. The material has to be resistant to long-term isothermal and cyclic oxidation conditions. In addition, the thermal stability of the alloy is of utmost importance. INCONEL® alloy 617 is a solid solution, nickel - chromium - cobalt - molybdenum alloy with an exceptional combination of high-temperature strength and oxidation and carburization resistance. In this paper, the performance of alloy 617 in isothermal and cyclic oxidation, carburization and burner rig oxidation/sulfidation environments will be presented. In addition some mechanical properties data will be included to show the stability of the alloy after exposure to high temperatures for extended periods of time. For comparison the data obtained on such alloys as INCO® alloy HX and Haynes® alloys 188 and 230 will also be reported.
Sound Propagation Calculation Over Larger Distances on a Standardized Basis According to the German VDI Regulations No. 2714
Authors: Schneider Manfred
Published: March 2015

In order to obtain permission for the construction of a new gas compressor station or other industrial facility, the future user has to submit a comprehensive forecast of sound immission levels to the competent supervisory authority, at the same time demonstrating by which means the noise level requirements in the vicinity of the facility can be met.

For this purpose, it is essential to calculate the sound propagation and associated attenuation effects on a basis which is reliable, verifiable and acceptable to the authority. The German VDI Regulations No. 2714 contain stipulations regarding standardized calculation procedures applicable in such cases.

This paper (ASME-presentation) discusses these calculation procedures for distances of > 200 m (> 650 feet) with special emphasis on screening and attenuation effects attributable to topography, weather influences and sound dissipation at high frequencies.