bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular and Pathogenic Diversity Among Brazilian Isolates of Xanthomonas albilineans Assessed with SSR Marker Loci
Authors: Tardiani Ana C. , Perecin Dilermando , Peixoto-Junior Rafael F. , Sanguino Alvaro , Landell Marcos M. G. , Beriam Luis O. , Nunes Daniel S. , Camargo Luis E. A. , Creste Silvana
Published: November 2013

Leaf scald is one of the most important diseases of sugarcane in Brazil. Despite its importance, little is known about the genetic and pathogenic variability of its causal agent, Xanthomonas albilineans. The genetic diversity of 44 X. albilineans isolates from diverse geographic regions of Brazil was assessed using 15 newly developed short sequence repeat (SSR) loci designed from the genome sequence of X. albilineans strain GPE PC73. In addition, the aggressiveness of each isolate was evaluated by inoculating on a susceptible sugarcane cultivar and scoring the disease severity. Of the 15 SSR loci, 12 were polymorphic and produced 54 polymorphic alleles. The average number of polymorphic alleles per locus was 4.5, and ranged from 2 to 12 alleles. Phenetic analysis based on Nei's unbiased genetic distance, clustered the isolates into two major groups. Group I included 32 isolates from all four geographic regions studied, whereas group II included 9 isolates from two regions. Three isolates did not cluster within these groups. Analysis of disease severity data also revealed variability in aggressiveness among isolates but no correlation could be established with either SSR haplotypes or phenetic groups. Isolates with identical haplotypes differed in aggressiveness and vice versa. However, single marker-trait analysis revealed two markers associated with this trait.
Action at a distance: dependency sensitivity in a New World primate
Authors: Ravignani Andrea , Sonnweber Ruth-Sophie , Stobbe Nina , Fitch W. Tecumseh
Published: November 2013

Sensitivity to dependencies (correspondences between distant items) in sensory stimuli plays a crucial role in human music and language. Here, we show that squirrel monkeys (
Saimiri sciureus
) can detect abstract, non-adjacent dependencies in auditory stimuli. Monkeys discriminated between tone sequences containing a dependency and those lacking it, and generalized to previously unheard pitch classes and novel dependency distances. This constitutes the first pattern learning study where artificial stimuli were designed with the species' communication system in mind. These results suggest that the ability to recognize dependencies represents a capability that had already evolved in humans’ last common ancestor with squirrel monkeys, and perhaps before.
An asymptotic theory for waves guided by diffraction gratings or along microstructured surfaces
Authors: Antonakakis T. , Craster R. V. , Guenneau S. , Skelton E. A.
Published: November 2013

An effective surface equation, that encapsulates the detail of a microstructure, is developed to model microstructured surfaces. The equations deduced accurately reproduce a key feature of surface wave phenomena, created by periodic geometry, that are commonly called Rayleigh–Bloch waves, but which also go under other names, for example, spoof surface plasmon polaritons in photonics. Several illustrative examples are considered and it is shown that the theory extends to similar waves that propagate along gratings. Line source excitation is considered, and an implicit long-scale wavelength is identified and compared with full numerical simulations. We also investigate non-periodic situations where a long-scale geometrical variation in the structure is introduced and show that localized defect states emerge which the asymptotic theory explains.
Did Russia (Nearly) have a Facebook Revolution in 2011? Social Media's Challenge to Authoritarianism
Authors: White Stephen , McAllister Ian
Published: November 2013

What has become known as the ‘coloured revolutions’ first emerged as a distinctively post-Soviet phenomenon. In December 2011 it appeared as if Russia might have a coloured revolution of its own, having met several of the basic preconditions, notably a contested election and widespread social protest co-ordinated through social media. Using a national survey conducted immediately after the December 2011 Duma election, this article reveals widespread concern about the integrity of the election and strong public support for the demonstrators' demands. Social media, in the form of Facebook, are found to have been instrumental in disseminating information about the protests. The implications of these findings for the use of social media in future anti-regime protests are discussed.
Building Innovation Excellence of World Class: The Cluster as an Instrument of Spatial Governance in the European Union
Authors: Ahlqvist Toni
Published: November 2013

European spatial governance is becoming an intriguing mix of ideas from the economic, political and cultural spheres. This article asserts that, in the EU's spatial planning, the cluster is increasingly part of a hybrid spatial politics, here named the ‘cluster gaze’, based on the interplay of innovation‐oriented political rationality and spatial governance. To study this process, the article provides an empirical investigation into selected EU documentation. The investigation is based on two perspectives. First, the cluster is analysed as a mediating instrument to stimulate and rescale transnational market developments in the EU. Second, the cluster is studied as an instrument of spatial management — one that builds on a business managerial ethos and endorses a specific hierarchical spatial imaginary and a cluster evidence base to assess the productivity and efficiency of European clusters. Both of these perspectives pave the way for a European ‘politics of cluster excellence’ that is about the constant sharpening of cluster practices, continuous evaluation and ranking, and the enhancement of cluster performance to rise from the ‘European league’ towards the ‘world class’.
Mark–recapture of Cerambyx welensii in dehesa woodlands: dispersal behaviour, population density, and mass trapping efficiency with low trap densities
Authors: Torres‐Vila Luis M. , Sánchez‐González Álvaro , Merino‐Martínez Jesús , Ponce‐Escudero Francisco , Conejo‐Rodríguez Yolanda , Martín‐Vertedor Daniel , Ferrero‐García Juan J.
Published: November 2013

The longhorn beetle, Cerambyx welensii Küster (Coleoptera: Cerambycidae), is an emerging pest involved in oak decline episodes in dehesa open woodlands. Larvae are xylophagous and cause considerable physiological, mechanical, and structural damages to trees. Chemical and biological control are currently unsatisfactory. Recent research has shown that mass trapping with a high density of baited traps (40 traps ha−1) could be useful to manage C. welensii populations, although such a trap density was too high to be cost‐effective. In this 2‐year study (2010–2011) we investigated with mark–recapture methods in a large plot (1) the flight dispersal behaviour, (2) the adult population density, and (3) the efficiency of mass trapping at two low trap densities (one or four traps ha−1). Results indicated that many adults were sedentary (60%) but flying adults displayed a strong propensity to move, both sexes dispersing on average more than 200 m and one male and one female flying at least 540 and 349 m, respectively. Recapture rates were high (0.26–0.35) and population density was estimated to be 6–22 adults ha−1 with maximum likelihood models. Trapping efficiency ranged 48–61% with no significant effect of trap density or year. We conclude that results were not satisfactory enough to recommend mass trapping with low trap densities as control method for C. welensii and that more research is still required on the technical, ecological, and behavioural factors affecting control efficiency.
Functional neuroimaging in epileptic encephalopathies
Authors: Siniatchkin Michael , Capovilla Giuseppe
Published: November 2013

Epileptic encephalopathies (EEs) represent a group of severe epileptic disorders associated with cognitive and behavioral disturbances. The mechanisms of cognitive disability inEEs remain unclear. This review summarized neuroimaging studies that have tried to describe specific fingerprints of brain activation inEE. Although the epileptic activity can be generated individually in different brain regions, it seems likely that the activity propagates in a syndrome‐specific way. In someEEs, the epileptiform discharges were associated with an interruption of activity in the default mode network. In anotherEE, other mechanisms seem to underlie cognitive disability associated with epileptic activity, for example, abnormal connectivity pattern or interfering activity in the thalamocortical network. Further neuroimaging studies are needed to investigate the short‐term and long‐term impact of epileptic activity on cognition and development.
Experimental assessment of oral hygiene achieved by children wearing rapid palatal expanders, comparing manual and electric toothbrushes
Authors: Mazzoleni S , Bonaldo G , Pontarolo E , Zuccon A , De Francesco M , Stellini E
Published: November 2013

Objectives

The aim was to compare the efficacy of the electric versus the manual toothbrush in terms of the oral hygiene achieved by patients wearing rapid palatal expanders (RPEs).

Methods

Forty patients were randomly divided into two groups; one equipped with a manual toothbrush (Group A), the other with an electric toothbrush (Group B). Each child's plaque index (PI) and gingival index (GI) were calculated at banded molar level at times T0 (before banding), T1 (a month later), T2 (3 months later) and T3 (when the expander was removed). At each appointment, the PI and GI were recorded and the patient was remotivated.

Results

The level of oral hygiene achieved by the group using an electric toothbrush produced a greater improvement in the two indexes than in the group using the manual toothbrush that showed no statistically significant improvement (PI T0–T3: P = 0.309; GI T0–T3: P = 0.141). Both indexes dropped considerably in both groups from T0 to T2, but more so in the group B. From T2 to T3, although the electric toothbrush continued to be substantially more effective, Group B showed a statistically significant deterioration in the oral hygiene (PI +20%; GI +33%). Other assessments conducted on particular areas of the tooth showed improvements in the PI (−33%) for the vestibular region, and for the GI (−57%) in the palatal region among the patients in Group B, while there were no significant changes in these indexes in Group A.

Conclusions

Our findings show that the electric toothbrush is statistically more efficient in performing an adequate level of oral hygiene in children wearing RPE.
Cardiometabolic risk factors and insulin resistance in obese children and adolescents: relation to puberty
Authors: Tobisch B. , Blatniczky L. , Barkai L.
Published: November 2013

What is already known about this subject

The prevalence of obesity with concomitant increasing risk for having cardiometabolic diseases is rising in the childhood population.

Insulin resistance has a key role in metabolic changes in these children.

Insulin levels elevate as puberty commences in every individual.

What this study adds

Children with increased risk for cardiometabolic diseases show significant differences in insulin levels even before the onset of puberty compared with those without risks.

The pattern of appearance of dyslipidaemia also varies in children with risk factors even in the pre‐pubertal group from those without risk.

Children with metabolic syndrome display considerably pronounced changes in their metabolic parameters before the onset of puberty, which become more pronounced as puberty passes.

Background

Insulin resistance (IR) has a key role in the metabolic changes in obese children. In commencing puberty, the insulin levels elevate. It is not clear, however, how insulin levels develop if the metabolic syndrome appears.

Objectives

Metabolic changes were assessed in obese children before, during and after puberty to analyse the relationship between IR and puberty in subjects with and without metabolic syndrome.

Methods

Three hundred thirty‐four obese children (5–19 years) attended the study. The criteria of the International Diabetes Federation were used to assess the presence of cardiometabolic risks (CMRs). Subjects with increased CMR were compared with those without risk (nCMR). Pubertal staging, lipid levels, plasma glucose and insulin levels during oral glucose tolerance test were determined in each participant. IR was expressed by homeostasis model assessment (HOMA‐IR) and the ratio of glucose and insulin areas under the curve (AUC‐IR).

Results

Significantly higher AUC‐IR were found in pre‐pubertal CMR children compared with nCMR subjects (11.84 ± 1.03 vs. 8.00 ± 0.69; P < 0.01), but no difference was discovered during and after puberty. HOMA‐IR differs between CMR and nCMR only in post‐puberty (6.03 ± 1.26 vs. 2.54 ± 0.23; P < 0.01). CMR children have dyslipidaemia before the onset of puberty.

Conclusions

CMR is associated with increased postprandial IR in pre‐pubertal and increased fasting IR in post‐pubertal obese children. Dyslipidaemia appeared already in pre‐puberty in CMR children.
Beyond sports nutrition: the diverse role of dietitians at the Delhi 2010 Commonwealth Games
Authors: Burkhart S. J. , Pelly F. E.
Published: November 2013

Background

Although registered sports dietitians commonly assist athletes with training and competition nutrition advice, an emerging area of practice is focused around food provision and nutrition support provided at major competition events. The present study aimed, first, to identify the dietetic skills and scope of practice that dietitians may require to work in this environment as determined by the occasions of service provided by dietitians at a nutrition kiosk located in the dining hall at a major competition event and, second, to investigate athletes' opinion and usage of the nutrition services and the association with their type of sport and previous source of nutrition information.

Methods

Dietitians based at a nutrition kiosk recorded all enquiries (n = 383) and consultations (n = 60) from 23 September to 14 October 2010. A questionnaire was also distributed to athletes in the main dining hall over this period to investigate their opinion and use of nutrition support, as well as their previous source of nutrition information.

Results

Although athletes from Western regions made up the majority of the enquiries regarding food provision and special/therapeutic dietary requirements (predominately food allergy and intolerance), athletes from non‐Western regions, and those in weight category sports, had more sports nutrition enquiries and were more likely to request a consultation. A number of athletes (32%) reported no previous or one source of nutrition information, whereas only eight of 52 athletes who requested a consultation had prior nutrition assistance.

Conclusions

In addition to sport nutrition knowledge and experience, dietitians working in this environment are likely to require an understanding of cultural eating styles, food beliefs and customs, large‐scale food service operation, and local food availability.
Pharmacokinetic evaluation of oral dantrolene in the dog
Authors: Haraschak J. L. , Langston V. C. , Wang R. , Riggs C. , Fellman C. , Ross M. K. , Bulla C. , Lunsford K. , Mackin A. , Archer T.
Published: November 2013

The pharmacokinetics of dantrolene and its active metabolite, 5‐hydroxydantrolene, after a single oral dose of either 5 or 10 mg/kg of dantrolene was determined. The effects of exposure to dantrolene and 5‐hydroxydantrolene on activated whole‐blood gene expression of the cytokines interleukin‐2 (IL‐2) and interferon‐γ (IFN‐γ) were also investigated. When dantrolene was administered at a 5 mg/kg dose, peak plasma concentration (Cmax) was 0.43 μg/mL, terminal half‐life (t1/2) was 1.26 h, and area under the time–concentration curve (AUC) was 3.87 μg·h/mL. For the 10 mg/kg dose,Cmaxwas 0.65 μg/mL,t1/2was 1.21 h, and AUC was 5.94 μg·h/mL. For all calculated parameters, however, there were large standard deviations and wide ranges noted between and within individual dogs:t1/2, for example, ranged from 0.43 to 6.93 h,Cmaxratios ranged from 1.05 to 3.39, and relative bioavailability (rF) values ranged from 0.02 to 1.56. While activated whole‐blood expression ofIL‐2 andIFN‐γ as measured byqRT‐PCRwas markedly suppressed following exposure to very high concentrations (30 and 50 μg/mL, respectively) of both dantrolene and 5‐hydroxydantrolene, biologically and therapeutically relevant suppression of cytokine expression did not occur at the much lower drug concentrations achieved with oral dantrolene dosing.
An ecogenomic analysis of herbivore‐induced plant volatiles in Brassica juncea
Authors: Mathur Vartika , Tytgat Tom O. G. , Hordijk Cornelis A. , Harhangi Harry R. , Jansen Jeroen J. , Reddy A. Sankara , Harvey Jeffrey A. , Vet Louise E. M. , van Dam Nicole M.
Published: November 2013

Upon herbivore feeding, plants emit complex bouquets of induced volatiles that may repel insect herbivores as well as attract parasitoids or predators. Due to differences in the temporal dynamics of individual components, the composition of the herbivore‐induced plant volatile (HIPV) blend changes with time. Consequently, the response of insects associated with plants is not constant either. Using Brassica juncea as the model plant and generalist Spodoptera spp. larvae as the inducing herbivore, we investigated herbivore and parasitoid preference as well as the molecular mechanisms behind the temporal dynamics in HIPV emissions at 24, 48 and 72 h after damage. In choice tests, Spodoptera litura moth preferred undamaged plants, whereas its parasitoid Cotesia marginiventris favoured plants induced for 48 h. In contrast, the specialist Plutella xylostella and its parasitoid C. vestalis preferred plants induced for 72 h. These preferences matched the dynamic changes in HIPV blends over time. Gene expression analysis suggested that the induced response after Spodoptera feeding is mainly controlled by the jasmonic acid pathway in both damaged and systemic leaves. Several genes involved in sulphide and green leaf volatile synthesis were clearly up‐regulated. This study thus shows that HIPV blends vary considerably over a short period of time, and these changes are actively regulated at the gene expression level. Moreover, temporal changes in HIPVs elicit differential preferences of herbivores and their natural enemies. We argue that the temporal dynamics of HIPVs may play a key role in shaping the response of insects associated with plants.
Effect of syringe and aggregate filter administration on survival of transfused autologous fresh feline red blood cells
Authors: Heikes Brandon W. , Ruaux Craig G.
Published: November 2013

Objective

To assess the effect of transfusion using a syringe and microaggregate filter on short‐term survival and circulating half‐life of autologous feline RBCs.

Design

Prospective, internally controlled, observational study.

Setting

A University Teaching Hospital

Animals

Six apparently healthy, owned cats.

Interventions

Blood collection by jugular venipuncture. Transfusion with labeled, autologous, fresh RBCs.

Measurements and Main Results

Anticoagulated whole blood (35 mL/cat) was collected in 2 equal aliquots. RBCs were washed and labeled at 2 different biotin densities, before suspension in autologous plasma. Labeled RBCs were then transfused using 2 methods, gravity flow and pump delivery using a 20 mL syringe and 18 μm microaggregate filter.

Whole blood samples were collected from each cat at 2‐hour intervals for 12 hours following completion of the transfusions. Additional samples were collected at weekly intervals up to 6 weeks to assess circulating half‐life of the transfused cells. Cell survival was assessed via flow cytometry. The proportion of transfused cells remaining in each of the 2 populations was measured.

Biotinylated RBCs were readily detected in all cats over the 6‐week sampling period. There was a significant decrease in both populations of labeled cells over the 6‐week period (P< 0.01), as expected. There was no difference in probability that the RBCs would survive up to 12 hours immediately following transfusion, and no significant difference in survival between the 2 groups over 6 weeks. The average half‐life of all labeled cells was approximately 23 days.

Conclusions

We conclude that, in contrast to findings from dogs, transfusion of autologous feline RBCs using a syringe + aggregate filter method does not significantly impact short‐ or long‐term survival of the transfused cells.
VALIDATION OF A NOVEL TECHNIQUE FOR CREATING SIMULATED RADIOGRAPHS USING COMPUTED TOMOGRAPHY DATASETS
Authors: Mendoza Patricia , d'Anjou Marc‐André , Carmel Éric N. , Fournier Éric , Mai Wilfried , Alexander Kate , Winter Matthew D. , Zwingenberger Allison L. , Thrall Donald E. , Theoret Christine
Published: November 2013

Understanding radiographic anatomy and the effects of varying patient and radiographic tube positioning on image quality can be a challenge for students. The purposes of this study were to develop and validate a novel technique for creating simulated radiographs using computed tomography (CT) datasets. A DICOM viewer (ORS Visual) plug‐in was developed with the ability to move and deform cuboidal volumetric CT datasets, and to produce images simulating the effects of tube‐patient‐detector distance and angulation. Computed tomographic datasets were acquired from two dogs, one cat, and one horse. Simulated radiographs of different body parts (n = 9) were produced using different angles to mimic conventional projections, before actual digital radiographs were obtained using the same projections. These studies (n = 18) were then submitted to 10 board‐certified radiologists who were asked to score visualization of anatomical landmarks, depiction of patient positioning, realism of distortion/magnification, and image quality. No significant differences between simulated and actual radiographs were found for anatomic structure visualization and patient positioning in the majority of body parts. For the assessment of radiographic realism, no significant differences were found between simulated and digital radiographs for canine pelvis, equine tarsus, and feline abdomen body parts. Overall, image quality and contrast resolution of simulated radiographs were considered satisfactory. Findings from the current study indicated that radiographs simulated using this new technique are comparable to actual digital radiographs. Further studies are needed to apply this technique in developing interactive tools for teaching radiographic anatomy and the effects of varying patient and tube positioning.
Unsteady Two-Dimensional Stagnation-Point Flow and Heat Transfer of a Viscous, Compressible Fluid on an Accelerated Flat Plate
Authors: Mozayyeni H. R. , Rahimi Asghar B.
Published: November 2013

The general formulation and exact solution of the Navier–Stokes and energy equations regarding the problem of steady and unsteady two-dimensional stagnation-point flow and heat transfer is investigated in the vicinity of a flat plate. The plate is moving at time-dependent or constant velocity towards the main low Mach number free stream or away from it. The main stream impinges along z-direction on the flat plate with strain rate a and produces two-dimensional flow. The fluid is assumed to be viscous and compressible. The density of the fluid is affected by the existing temperature difference between the plate and potential far field flow. Suitably introduced similarity transformations are used to reduce the governing equations to a coupled system of ordinary differential equations. Finite Difference Scheme is used to solve these non-linear ordinary differential equations. The obtained results are presented over a wide range of parameters characterizing the problem. It is revealed that the significance of the increase of thermal expansion coefficient, β, and wall temperature on velocity and temperature distributions is much more noticeable for a plate moving away from impinging flow. Moreover, negligible shear stress and heat transfer is reported between the plate and fluid viscous layer close to the plate for a wide range of β coefficient when the plate moves away from incoming far field flow.
Electrochemical Behaviours of Titanium Nitride (TiN) and Chromium Nitride (CrN) Based PVD Coating Systems
Authors: Cai Feng , Huang Xiao , Yang Qi
Published: November 2013

Hard coatings applied to steel components prevent corrosion attacks while at the same time mitigate erosion attack. However, the presence of process related through-coating defects such as pin holes, voids and growth defects, provides accesses for corrosive media to metal substrates, initializing pitting corrosion and eventually resulting in coating failure. This research studies the corrosion behavior of PVD TiN and CrN (CrSiCN) coated steels in 3.5 wt. % NaCl aqueous solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results revealed that in a coating-substrate system, effective diffusion coefficient and diffusion layer thickness control the corrosion resistance; both factors are found to be related to coating microstructure. A denser and thicker coating structure are shown to have lower effective diffusion coefficients and greater effective diffusion layer thicknesses and consequently provided a high resistance to electrochemical corrosion.
An Optimizing Method to Balance Aerodynamic Loading for Gas Turbine Engine Preliminary Design
Authors: Tu Qiuye , Huang Xianzhong , Shi Yang , Yang Kun , Zhou Li
Published: November 2013

This paper presents a method to balance aerodynamic loading by optimizing the combined efficiencies of co-axial compressors and turbines for engine preliminary design. Relationships between the aerodynamic and dimensional parameters for co-axial compressors and turbines were set up by nonlinear equations. And the boundary conditions of the equations are thermodynamic parameters and Smith Charts of compressors and turbines.

The process of the method includes the initial value guess, reference point determination and aerodynamic optimization. The first step solves approximate stage numbers for co-axial compressors and turbines, and other initial values used in the second step. In the second step, an appropriate solution of the equations determines a reference point on the Smith Chart. The first step is required for a better convergence in the second step due to the nature of the Newton-Raphson solver. In the third step, the combined efficiencies of co-axial compressors and turbines are optimized under the specified constraints.

An optimizing tool was developed based on the proposed method. An example of a core engine was analyzed by using this tool. The results showed the reliability and high fidelity of the method.
Flow Simulation Around a Rim-Driven Wind Turbine and in Its Wake
Authors: Kaiser Bryan E. , Poroseva Svetlana V. , Snider Michael A. , Hovsapian Rob O. , Johnson Erick
Published: November 2013

A relatively high free stream wind velocity is required for conventional horizontal axis wind turbines (HAWTs) to generate power. This requirement significantly limits the area of land for viable onshore wind farm locations. To expand a potential for wind power generation and an area suitable for onshore wind farms, new wind turbine designs capable of wind energy harvesting at low wind speeds are currently in development.

The aerodynamic characteristics of such wind turbines are notably different from industrial standards. The optimal wind farm layout for such turbines is also unknown. Accurate and reliable simulations of a flow around and behind a new wind turbine design should be conducted prior constructing a wind farm to determine optimal spacing of turbines on the farm.

However, computations are expensive even for a flow around a single turbine. The goal of the current study is to determine a set of simulation parameters that allows one to conduct accurate and reliable simulations at a reasonable cost of computations. For this purpose, a sensitivity study on how the parameters variation influences the results of simulations is conducted. Specifically, the impact of a grid refinement, grid stretching, grid cell shape, and a choice of a turbulent model on the results of simulation of a flow around a mid-sized Rim Driven Wind Turbine (U.S. Patent 7399162) and in its near wake is analyzed. This wind turbine design was developed by Keuka Energy LLC.

Since industry relies on commercial software for conducting flow simulations, STAR-CCM+ software [1] was used in our study. A choice of a turbulence model was made based on the results from our previous sensitivity study of flow simulations over a rotating disk [2].
Faster Design of Gas Turbine Parts Using Rapid Prototype Models for Verification of Coolant Flow Characteristics
Authors: Sedlov Andrey , Bauer Andreas , Mozharov Alexey , Gritsch Michael , Kostege Valery
Published: November 2013

One of the keys to successful time-to-market introduction of a gas turbine blading upgrade package is fast-track development. Cooled turbine blades should match the designed coolant mass flow from the first iteration, otherwise, lengthy and expensive wax or core die rework has to be done.

Use of rapid prototyping for cooled components allows verification of their flow characteristics during the design phase and the check/calibration of flow predictions, prior to manufacturing. The present paper discusses features of the rapid prototyping process (selective laser sintering) in their application to plastic models of hot gas path components of modern heavy-duty gas turbines. A tailored sintering process was developed and successfully applied also to film cooled parts. Rapid prototype models were flow tested and then design changes were made to achieve the required levels of cooling air flow. Wax and core dies were produced, taking the design changes into account. Coolant flow characteristics of cast and machined parts were compared with those of rapid prototype models and with the design intent for a wide set of configurations and flow conditions. Comparison demonstrates good agreement in flow characteristics between prototyped and production parts, and thus confirms the applicability and reliability of this approach. Use of rapid prototype models significantly reduced the project duration, eliminated rework cost for casting tooling, and ultimately lead to a higher quality end product.
SCO2PE Operating Experience and Validation and Verification of KAIST_TMD
Authors: Lee Jekyoung , Lee Jeong Ik , Ahn Yoonhan , Kim Seong Gu , Cha Jae Eun
Published: November 2013

Supercritical carbon dioxide (S-CO2) Brayton cycle has gaining attention due to its compactness and high efficiency at intermediate temperature range of turbine inlet temperature. Thus, many research groups have been trying to develop their own S-CO2 Brayton cycle technology or component design technology. KAIST research team has been trying to develop a S-CO2 turbomachinery design methodology. As a part of this effort, In-House code KAIST_TMD (KAIST Turbomachinery Design) was developed based on open literatures. KAIST_TMD can reflect real gas effect since it uses precise equations and property database rather than ideal gas assumptions. Most special characteristic of KAIST_TMD is that KAIST_TMD can design both of radial type and axial type turbomachineries so it can compare performance of both radial and axial turbomachineries under the same operating conditions. KAIST_TMD provides geometry of turbomachinery and off design performance map also. This research team built a S-CO2 Pump Experiment facility (SCO2PE) to experience the S-CO2 loop operation and to perform validation and verification of KAIST_TMD in near future. Canned motor pump and shell and tube type heat exchanger were installed as the main components of SCO2PE. Main objectives of this paper are to present preliminary experimental data and share the operating experience and troubleshooting of the facility. Data analysis and detailed discussions about an experimental procedure and major issues when pump operates near the critical point will be presented in the paper. As a result, preliminary data were obtained that can be used for improving the facility to increase accuracy of the data for future validation and verification of KAIST_TMD for radial compressor/pump design.
In-Situ Study on Coaxing During Vibration-Based Bending Fatigue of Inconel 625 and 718
Authors: Scott-Emuakpor Onome , Schwartz Jeremy , George Tommy , Cross Charles , Holycross Casey , Shen M. H. Herman
Published: November 2013

This study observes coaxing effects on aerospace nickel alloys during vibration-based bending fatigue loading. The purpose of this analysis is to determine if Goodman diagrams can be constructed using bending fatigue life data at experimentally defined cycles to failure. The methodology for controlling the number of cycles to failure requires a series of understressing steps, where stress amplitude is incrementally increased at each step. This method, known as the step-test procedure, states that, for some materials, the stress amplitude corresponding to the controlled cycles-to-failure can be determined through linear interpolation between the failure step and the previous non-failure step. Using the step-test procedure, experimental bending fatigue life results were gathered from cold-rolled Inconel 625 and 718 plate specimens. These bending loads are applied with a vibration-based experimental method, known as the George fatigue method, which utilizes modal vibration for fatigue loading. The fatigue life results from the George fatigue method are compared to life data from previously published constant stress amplitude experiments to determine if coaxing affects the fatigue performance of the Inconel materials. Results show that Inconel 625 has an improved fatigue performance that could be attributed to several possible factors, including coaxing, while the Inconel 718 data is shown to be within a 50% confidence band of constant stress amplitude data from the same material stock. The findings in this study increases the knowledge necessary to attain more relevant and less conservative empirical data for designing against high cycle fatigue (HCF) failure of complex gas turbine engine components.
Shock Induced Vortices in Transonic Compressors: Physical Interpretations
Authors: Knobbe Henry , Nicke Eberhard , Cornelius Christian
Published: November 2013

Unsteady aerodynamics is becoming more and more important for future compressor improvements. It has to be taken into account to reduce the amount of uncertainties for increasing the performance. Uncertainties regarding unsteady blade row interaction are difficult to approximate due to the complex flow phenomena and the high computational effort to evaluate these phenomena. The optimal axial gapping for transonic compressors is particularly difficult to define. A wide range of axial gappings for two different state of the art compressor front stages (F-class and DLR Rig250) have been simulated to understand the underlying physics and to derive design rules for the optimal axial gapping. The incidence angle reduction due to shock induced vortices has not jet been fully investigated. Predicting the exact vortex trajectory in the rotor passage would be a critical step in assessing this reduction in incidence angle. A function to predict the deviation compared to the steady state compressor performance is usefull for future design processes.
Grid Stability: Gas Turbines for Primary Reserve
Authors: DiCampli James , Schulke William
Published: November 2013

Power grids are continually subjected to variations in load demand, leading to imbalances between generation and consumption. Such imbalances have an impact on the frequency level, requiring ongoing frequency control. Timely response of sufficient magnitude is critical to ensure grid stability. Without appropriate controls, variation in frequency levels can compound, leading to trips or even blackouts.

Primary Frequency Control (PFC) and Regulation Margin Control (RMC) have recently become a requirement for gas turbine generators (GTG) by many transmission grid authorities. PFC provides grid stability by allowing the gas turbine to automatically increase (or decrease) load when a grid frequency deviation occurs outside of a frequency band, and maintains this increased (or decreased) load while the deviations persist. RMC is used to ensure that a percentage of the GTG generating capability is reserved for use when grid frequency excursions occur.

There are different grid control regulations for different countries and regions. For example, the European Grid Code requires enough Primary Reserve set aside to support a +/−200 mHz grid frequency deviation with associated response times. The GTG must keep a percentage of the unit’s power capacity, or Primary Reserve, available for this purpose. The size of Primary Reserve power contributed by the grid frequency deviation is determined by the RMC Margin and PFC Droop settings, and must be managed under a wide range of operating and ambient conditions.

This paper reviews field test results and lessons learned in developing an approach to meeting the grid requirements. This includes the PFC reserve power response to frequency deviations, associated tolerances, and additional controls required to optimize the spray-intercooling power augmentation system.
Experimental and Numerical Investigation of Near-Tip Flow Field in an Axial Flow Compressor Rotor: Part I — Flow Characteristics at Stable Operating Conditions
Authors: Wu Yanhui , Wu Junfeng , Zhang Haoguang , Chu Wuli
Published: November 2013

Systematical casing pressure measurements were undertaken to supplement instantaneous experiment data to available database of a high-speed small-scale compressor rotor, which was crucial for understanding the flow mechanism of short-length scale stall inception. At the same time, improved full-annulus simulations were conducted to assist in interpretation of experimental observations. In Part I of current investigation, FFT (fast Fourier transformation) and STFT (short time Fourier transformation) analyses of instantaneous casing pressure signals were conducted to conclude flow characteristics near casing at stable operating conditions, and reasonable explanation of experimental observations was given in combination with the current and previous numerical results.

FFT analyses of casing pressure signals showed a characteristic hump with varying band lower than blade passing frequency (BPF) appeared at near-stall stable conditions. This indicated that an unsteady phenomenon emerged from the near-tip flow field for the test rotor. The variation in the amplitude of characteristic hump implied that underlying flow mechanism leading to the emergence of unsteady phenomenon originated from a location near leading edge and within passage. Further STFT analyses showed that the active frequency of this unsteady phenomenon varied with time, thus leading to the appearance of excitation band in FFT analysis results. FFT and STFT analyses of monitoring results of numerical probes arranged in absolute frame showed a similar unsteady phenomenon appeared in the simulated near-tip flow field. Detailed analyses of simulated instantaneous flow fields and comparison with measured flow characteristics indicated that the unsteady flow phenomenon observed in experiments was equivalent to rotating instability (RI) as far as non-uniform tip loading distribution was concerned, and the formation and activity of tip secondary vortex (TSV) was the flow mechanism of emergence of RI.
Experimental and Numerical Investigation of Near-Tip Flow Field in an Axial Flow Compressor Rotor: Part II — Flow Characteristics at Stall Inception Condition
Authors: Wu Yanhui , Wu Junfeng , Zhang Haoguang , Chu Wuli
Published: November 2013

Systematical casing pressure measurements were undertaken to supplement instantaneous experiment data to available database of a high-speed small-scale compressor rotor, which was crucial for understanding the flow mechanism of short-length scale stall inception. At the same time, improved full-annulus simulations were conducted to assist in interpretation of experimental observations. In Part II of current investigation, original instantaneous casing pressure signals and STFT (short time Fourier transformation) analyses were conducted to conclude flow characteristics near casing at stall inception operating condition, and reasonable explanation of experimental observations was given in combination with numerical results.

The current experimental investigation showed the stall inception of the test rotor was triggered by a spike, propagating at about 66.7%, which evolved into a single fully-developed stall cell. STFF analysis of pressure signal detected by probe located at tip leading edge showed that frequency peaks with varied band, which already observed in near-stall stable flow condition in Part I, was still a dominant flow feature before spike emergence, though it was hardly perceived after spike emergence due to a sudden increase in the overall energy of pressure signal, which attributed to the interface of incoming and tip clearance flow beyond leading edge plane according to STFT results. Monitoring results of static pressures in the absolute frame from current simulation and the corresponding FFT and STFT analyses showed a similar flow field evolution process as those observed in experiment. The current investigation provided adequate experimental evidence to support the previous simulation results in which a viewpoint of formation and activity of tip secondary vortex (TSV) was proposed as the underlying flow mechanism of the origin of unsteadiness near casing at near-stall stable operating conditions, and emergence of spike during the transition of flow field into unstable state, and further verified that the unsteady flow phenomenon observed in near-stall stable flow condition was equivalent to rotating instability (RI), thus establishing the causal linkage between RI and stall inception for the test rotor.
Sensitivity Analysis and Numerical Stability Analysis of the Algorithms for Predicting the Performance of Turbines
Authors: Wei Ming , Wang Yonghong , Song Huafen
Published: November 2013

Sensitivity and numerical stability of an algorithm are two of the most important criteria to evaluate its performance. For all published turbine flow models, except Wang method, can be named the ‘top-down’ method (TDM) in which the performance of turbines is calculated from the first stage to the last stage row by row; only Wang method originally proposed by Yonghong Wang can be named the ‘bottom-up’ method (BUM) in which the performance of turbines is calculated from the last stage to the first stage row by row. To find the reason why the stability of the two methods is of great difference, the Wang flow model is researched. The model readily applies to TDM and BUM. How the stability of the two algorithms affected by input error and rounding error is analyzed, the error propagation and distribution in the two methods are obtained. In order to explain the problem more intuitively, the stability of the two methods is described by geometrical ideas. To compare with the known data, the performance of a particular type of turbine is calculated through a series of procedures based on the two algorithms. The results are as follows. The closer the operating point approaches the critical point, the poorer the stability of TDM is. The poor stability can even cause failure in the calculation of TDM. However BUM has not only good stability, but also high accuracy. The result provides an accurate and reliable method (BUM) for estimating the performance of turbines, and it can apply to all one-dimensional performance calculation method for turbine.
Unsteady Simulation of a Two-Stage Cooled High Pressure Turbine Using an Efficient Non-Linear Harmonic Balance Method
Authors: Subramanian Venkataramanan , Custer Chad H. , Weiss Jonathan M. , Hall Kenneth C.
Published: November 2013

The harmonic balance method is a mixed time domain and frequency domain approach for efficiently solving periodic unsteady flows. The implementation described in this paper is designed to efficiently handle the multiple frequencies that arise within a multistage turbomachine due to differing blade counts in each blade row. We present two alternative algorithms that can be used to determine which unique set of frequencies to consider in each blade row. The first, an all blade row algorithm, retains the complete set of frequencies produced by a given blade row’s interaction with all other blade rows. The second, a nearest neighbor algorithm, retains only the dominant frequencies in a given blade row that arise from direct interaction with the adjacent rows. A comparison of results from a multiple blade row simulation based on these two approaches is presented. We will demonstrate that unsteady blade row interactions are accurately captured with the reduced frequency set of the nearest neighbor algorithm, and at a lower computational cost compared to the all blade row algorithm.

An unsteady simulation of a two-stage, cooled, high pressure turbine cascade is achieved using the present harmonic balance method and the nearest neighbor algorithm. The unsteady results obtained are compared to steady simulation results to demonstrate the value of performing an unsteady analysis. Considering an unsteady flow through a single blade row turbine blade passage, it is further shown that unsteady effects are important even if the objective is to obtain accurate time-averaged integrated values, such as efficiency.
A Fluid-Structure Coupling Method for Rotor Blade Unrunning Design
Authors: Yang Hui , Zheng Yun
Published: November 2013

This paper reports a numerical method for the design of a unrunning blade with the consideration of both nonlinear aerodynamic and centrifugal forces. Accurate prediction of blade manufacture shape in turbomachinery is crucial for performance, efficiency and aeroelastic stability. An iterative procedure starting from a given blade running shape is developed to predict the manufacture blade shape.

The model is based on a three-dimensional (3D) unsteady nonlinear Navier-Stokes Computational Fluid Dynamics (CFD) solver and the mode superposition structural dynamic theory in conjunction with a finite element structural model for the rotor blade. The manufacture profile of the blade (“Cold” blade) is estimated from the running blade shape (“Hot” blade). ANSYS finite element code is used to compute the deflection of the cold blade due to centrifugal loads. A finite volume based 3D nonlinear CFD code, coupled with a mode superposition structural dynamic modal method, is employed to determine the blade deflection due to unsteady aerodynamic loading. The difference between the computed blade profile and the targeted hot blade shape is used to predict a new cold blade for the next iteration if the convergence criterion is not met.

The method is applied to predict the manufacture blade shape of a large-scale propfan and a NASA rotor 67 fan. The predicted blade profile and the twist angle of the blade at various spans are presented. The results show that improvements of the manufacture blade profile can be made by including proper nonlinear aerodynamic effect on the blade deflection in the numerical model. The results also illustrate that aerodynamic nonlinear effects on structural deformation should be included for a better cold blade design.