bluuebunny/crossref_metadata_2025 huggingface dataset:
Substance Use and Sexual Risk Behaviors Among American Indian and Alaska Native High School Students
Authors: de Ravello Lori , Everett Jones Sherry , Tulloch Scott , Taylor Melanie , Doshi Sonal
Published: December 2013

BACKGROUND

We describe the prevalence of behaviors that put American Indian and Alaska Native (AI/AN) high school students at risk for teen pregnancy and sexually transmitted infections (STIs) and the relationships among race/ethnicity and these behaviors.

METHODS

We analyzed merged 2007 and 2009 data from the national Youth Risk Behavior Survey, a biennial, self‐administered, school‐based survey of US students in grades 9‐12 (N = 27,912). Prevalence estimates and logistic regression, controlling for sex and grade, were used to examine the associations between race/ethnicity, and substance use, and sexual risk behaviors.

RESULTS

Of the 26 variables studied, the adjusted odds ratios (AOR) were higher among AI/AN than White students for 18 variables (ranging from 1.4 to 2.3), higher among AI/AN than Black students for 13 variables (ranging from 1.4 to 4.2), and higher among AI/AN than Hispanic students for 5 variables (ranging from 1.4 to 1.5). Odds were lower among AI/AN than Black students for many of the sexual risk‐related behaviors.

CONCLUSIONS

The data suggest it is necessary to develop targeted, adolescent‐specific interventions aimed at reducing behaviors that put AI/AN high school students at risk for teen pregnancy, STI/HIV, and other health conditions.
Health and Academic Achievement: Cumulative Effects of Health Assets on Standardized Test Scores Among Urban Youth in the United States
Authors: Ickovics Jeannette R. , Carroll‐Scott Amy , Peters Susan M. , Schwartz Marlene , Gilstad‐Hayden Kathryn , McCaslin Catherine
Published: December 2013

BACKGROUND

The Institute of Medicine (2012) concluded that we must “strengthen schools as the heart of health.” To intervene for better outcomes in both health and academic achievement, identifying factors that impact children is essential. Study objectives are to (1) document associations between health assets and academic achievement, and (2) examine cumulative effects of these assets on academic achievement.

METHODS

Participants include 940 students (grades 5 and 6) from 12 schools randomly selected from an urban district. Data include physical assessments, fitness testing, surveys, and district records. Fourteen health indicators were gathered including physical health (eg, body mass index [BMI]), health behaviors (eg, meeting recommendations for fruit/vegetable consumption), family environment (eg, family meals), and psychological well‐being (eg, sleep quality). Data were collected 3‐6 months prior to standardized testing.

RESULTS

On average, students reported 7.1 health assets out of 14. Those with more health assets were more likely to be at goal for standardized tests (reading/writing/mathematics), and students with the most health assets were 2.2 times more likely to achieve goal compared with students with the fewest health assets (both p < .001).

CONCLUSIONS

Schools that utilize nontraditional instructional strategies to improve student health may also improve academic achievement, closing equity gaps in both health and academic achievement.
Mobility and Public Transport Use Abilities of Children and Young Adults With Intellectual Disabilities: Results From the 3‐Year Nordhorn Public Transportation Intervention Study
Authors: Haveman Meindert , Tillmann Vera , Stöppler Reinhilde , Kvas Štefan , Monninger Daniel
Published: December 2013

In addition to individual mobility needs, today's society requires spatial mobility within the expected social role of a pedestrian and bus passenger. A social‐ecological model helps to identify opportunities to promote participation in traffic wayfinding by recognizing the multiple factors that influence an individual's behavior. The Nordhorn Public Transportation Intervention Study project in Germany had the aim of increasing the independent use of public transportation by students with intellectual disabilities (ID) through interventions in the social and physical environment. Success of the project was measured by the number of students who were able to independently go from home to school at the end compared with the start of the project and by the skills students evidenced with coping with barriers on their way to school at the end of the project compared with their baseline skills. This multicenter study included various types of interventions: assessment of mobility/traffic competency, mobility integrated individual educational plans, mobility and traffic curriculum, information for teachers and parents, training for bus drivers, real‐life traffic training, support by mobility trainers and trip coaches, adaptations to streets and buses, and incident management including the use of communication devices (e.g., mobile phones with Global Positioning System). At the start of the project, <1% of the 124 students with ID used public transport to get to school, 3 years later, the proportion increased to 65.3%. On 19 of 29 items, students showed relevant and statistically significant improvement of skills in public transport use and traffic wayfinding behavior compared with the situation at baseline.
Arctic root‐associated fungal community composition reflects environmental filtering
Authors: Blaalid Rakel , Davey Marie L. , Kauserud Håvard , Carlsen Tor , Halvorsen Rune , Høiland Klaus , Eidesen Pernille B.
Published: December 2013

There is growing evidence that root‐associated fungi have important roles in Arctic ecosystems. Here, we assess the diversity of fungal communities associated with roots of the ectomycorrhizal perennial herbBistorta viviparaon theArctic archipelago ofSvalbard and investigate whether spatial separation and bioclimatic variation are important structuring factors of fungal community composition. We sampled 160 plants ofB. viviparafrom 32 localities acrossSvalbard.DNAwas extracted from entire root systems, and 454 pyrosequencing ofITS1 amplicons was used to profile the fungal communities. The fungal communities were predominantly composed ofBasidiomycota (55% of reads) andAscomycota (35%), with the ordersThelephorales (24%),Agaricales (13.8%),Pezizales (12.6%) and Sebacinales (11.3%) accounting for most of the reads. Plants from the same site or region had more similar fungal communities to one another than plants from other sites or regions, and sites clustered together along a weak latitudinal gradient. Furthermore, a decrease in per‐plantOTUrichness with increasing latitude was observed. However, no statistically significant spatial autocorrelation between sites was detected, suggesting that environmental filtering, not dispersal limitation, causes the observed patterns. Our analyses suggest that while latitudinal patterns in community composition and richness might reflect bioclimatic influences at global spatial scales, at the smaller spatial scale of the Svalbard archipelago, these changes more likely reflect varied bedrock composition and associated edaphic factors. The need for further studies focusing on identifying those specific bioclimatic and edaphic factors structuring root‐associated fungal community composition at both global and local scales is emphasized.
Environmental gradients predict the genetic population structure of a coral reef fish in the Red Sea
Authors: Nanninga Gerrit B. , Saenz‐Agudelo Pablo , Manica Andrea , Berumen Michael L.
Published: December 2013

The relatively recent fields of terrestrial landscape and marine seascape genetics seek to identify the influence of biophysical habitat features on the spatial genetic structure of populations or individuals. Over the last few years, there has been accumulating evidence for the effect of environmental heterogeneity on patterns of gene flow and connectivity in marine systems. Here, we investigate the population genetic patterns of an anemonefish, Amphiprion bicinctus, along the Saudi Arabian coast of the Red Sea. We collected nearly one thousand samples from 19 locations, spanning approximately 1500 km, and genotyped them at 38 microsatellite loci. Patterns of gene flow appeared to follow a stepping‐stone model along the northern and central Red Sea, which was disrupted by a distinct genetic break at a latitude of approximately 19°N. The Red Sea is characterized by pronounced environmental gradients along its axis, roughly separating the northern and central from the southern basin. Using mean chlorophyll‐a concentrations as a proxy for this gradient, we ran tests of isolation by distance (IBD, R2 = 0.52) and isolation by environment (IBE, R2 = 0.64), as well as combined models using partial Mantel tests and multiple matrix regression with randomization (MMRR). We found that genetic structure across our sampling sites may be best explained by a combined model of IBD and IBE (Mantel: R2 = 0.71, MMRR: R2 = 0.86). Our results highlight the potential key role of environmental patchiness in shaping patterns of gene flow in species with pelagic larval dispersal. We support growing calls for the integration of biophysical habitat characteristics into future studies of population genetic structure.
Hexanoic acid protects tomato plants against Botrytis cinerea by priming defence responses and reducing oxidative stress
Authors: Finiti Ivan , de la O. Leyva María , Vicedo Begonya , Gómez‐Pastor Rocío , López‐Cruz Jaime , García‐Agustín Pilar , Real Maria Dolores , González‐Bosch Carmen
Published: December 2013

Treatment with the resistance priming inducer hexanoic acid (Hx) protects tomato plants from Botrytis cinerea by activating defence responses. To investigate the molecular mechanisms underlying hexanoic acid‐induced resistance (Hx‐IR), we compared the expression profiles of three different conditions: Botrytis‐infected plants (Inf), Hx‐treated plants (Hx) and Hx‐treated + infected plants (Hx+Inf). The microarray analysis at 24 h post‐inoculation showed that Hx and Hx+Inf plants exhibited the differential expression and priming of many Botrytis‐induced genes. Interestingly, we found that the activation by Hx of other genes was not altered by the fungus at this time point. These genes may be considered to be specific targets of the Hx priming effect and may help to elucidate its mechanisms of action. It is noteworthy that, in Hx and Hx+Inf plants, there was up‐regulation of proteinase inhibitor genes, DNA‐binding factors, enzymes involved in plant hormone signalling and synthesis, and, remarkably, the genes involved in oxidative stress. Given the relevance of the oxidative burst occurring in plant–pathogen interactions, the effect of Hx on this process was studied in depth. We showed by specific staining that reactive oxygen species (ROS) accumulation in Hx+Inf plants was reduced and more restricted around infection sites. In addition, these plants showed higher ratios of reduced to oxidized glutathione and ascorbate, and normal levels of antioxidant activities. The results obtained indicate that Hx protects tomato plants from B. cinerea by regulating and priming Botrytis‐specific and non‐specific genes, preventing the harmful effects of oxidative stress produced by infection.
Perfluorooctanoate Exposure in a Highly Exposed Community and Parent and Teacher Reports of Behaviour in 6–12‐Year‐Old Children
Authors: Stein Cheryl R. , Savitz David A. , Bellinger David C.
Published: December 2013

Background

In toxicology studies, perfluorinated compounds affect fetal growth, development, viability, and postnatal growth. There are limited epidemiologic studies on child development.

Methods

We recruited and evaluated 321 children who participated in the C8 Health Project, a 2005–06 survey in a mid‐Ohio Valley community highly exposed to perfluorooctanoate (PFOA) through contaminated drinking water. We examined associations between measured childhood PFOA serum concentration and mother and teacher reports of executive function (Behaviour Rating Inventory of Executive Function), attention deficit hyperactivity disorder (ADHD)‐like behaviour (Conner's ADHD Diagnostic and Statistical Manual of Mental Disorders IV Scales), and behavioural problems (Behaviour Assessment System for Children) assessed 3 to 4 years later at ages 6–12 years.

Results

Overall, neither reports from mothers nor teachers provided clear associations between exposure and child behaviour. Mother reports, however, did suggest favourable associations between exposure and behaviour among boys and adverse associations among girls. On the composite scale from the Behaviour Rating Inventory of Executive Function (n = 318), PFOA exposure had a favourable association among boys (highest vs. lowest quartile β = −6.39; 95% confidence interval [CI] −11.43, −1.35) and an adverse association among girls (highest vs. lowest quartile β = 4.42; 95% CI −0.03, 8.87; interaction P = 0.01). Teacher reports (n = 189) replicated some, but not all of the sex interactions observed in mothers' reports.

Conclusions

Aggregate results did not suggest adverse effects of PFOA on behaviour, but sex‐specific results raise the possibility of differing patterns by sex. Results are not consistent between mothers' and teachers' reports. Effect modification by sex may warrant further investigation.
On the Quantitative Doctrine of the Mean
Authors: Mintoff Joe
Published: December 2013

Aristotle's doctrine of the mean is expressed in quantitative terms, but this has been hard for some people to take literally, its more elaborate versions sometimes being described as “extremely silly.” Roughly two books of the Nicomachean Ethics are permeated with talk of character traits which are either deficient or excessive, however, and the aim of this paper is to examine how the doctrine might meet the objections of its critics.
The PpCMT chromomethylase affects cell growth and interacts with the homolog of LIKE HETEROCHROMATIN PROTEIN 1 in the moss Physcomitrella patens
Authors: Dangwal Meenakshi , Kapoor Sanjay , Kapoor Meenu
Published: December 2013

Chromomethylases (CMTs) are plant‐specific cytosine DNA methyltransferases that are involved in maintenance of CpNpG methylation. In seed plants, histone methylation and interaction of CMT with LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is essential for recruitment of CMT to target sites. LHP1 has been characterized as a putative component of the POLYCOMB REPRESSIVE COMPLEX1 (PRC1) in plants, and functions downstream of PRC2 to maintain genes in repressed state for orchestrated development. In the present study, we show that targeted disruption of PpCMT results in an approximately 50% reduction in global cytosine methylation levels. This affects growth of apical cells, predominantly growth of side branch initials emerging from chloronema cells. In some places, these cells develop thick walls with plasmolyzed cellular contents. Transcript accumulation patterns of genes involved in apical cell extension and metabolism of hemicelluloses, such as xyloglucans, in the primary cell walls decreased many fold in ppcmt mutant lines, as determined by real‐time PCR. Using yeast two‐hybrid method and bimolecular fluorescence complementation assay, we show that PpCMT and PpLHP1 interact through their chromo domains, while PpLHP1 homodimerizes through its chromo shadow domain. The results presented in this study provide insight into the role of the single chromomethylase, PpCMT, in proliferation of protonema filaments, and shed light on the evolutionary conservation of proteins interacting with these methylases in the early land plant, Physcomitrella patens.
DropArray™, a Wall‐Less 96‐Well Plate for Uptake and Immunofluorescence Microscopy, Confirms CD22 Recycles
Authors: Ingle Gladys S. , Scales Suzie J.
Published: December 2013

CD22 is a cell surface glycoprotein restricted to normal and malignant B‐cells and is the target of several anti‐CD22 antibody‐based cancer therapies. For therapeutic antibody‐payload conjugates, it is important to understand the subcellular trafficking of anti‐CD22 antibodies to optimize antibody and/or linker–drug properties to maximize antitumor efficacy. It is agreed that anti‐CD22 antibodies rapidly internalize, but controversial whether they recycle or are degraded in lysosomes, and it is unclear if trafficking is antibody or cell‐type dependent. No studies examined anti‐CD22 trafficking to either pathway in B‐cells over time by dual immunofluorescence microscopy, likely partly because multiple samples of suspension cells are tedious to stain. We overcame this by using DropArray™, a novel wall‐less 96‐well plate technology allowing rapid simultaneous staining of suspension or adherent cells in small (10–20 μL) volumes. We examined the time‐course of trafficking of five different anti‐CD22 antibodies in eight B‐cell lines representing four B‐cell cancer types and show that in all cases antibodies internalize within 5 min and recycle, with only small amounts eventually trafficking to lysosomes. CD22 also localizes to recycling endosomes at steady state in the absence of antibody. Our data may help explain the differential efficacies of anti‐CD22 antibodies conjugated to different therapeutic payloads.
Real-Time Detection of Processing Flaws During Inertia Friction Welding of Critical Components
Authors: Hartman Daniel A.
Published: December 2013

Outside of statistical process control, current manufacturing quality control is founded upon a “make-then-inspect” mindset [1]. While this approach is an important part of the quality control process, post-process inspection is labor intensive, a bottleneck to continuous production throughput, costly, subject to human interpretation, and susceptible to missing subtle defects. This paper presents the application of in-process quality control (IPQC) during inertia friction welding of critical components.

This paper is a follow-on to a preliminary investigation into a new sensing technique for real-time inspection of product quality during friction welding [2]. The previous effort explored the feasibility of modeling the approach that an experienced friction welding operator uses to distinguish anomalous process behavior during friction welding. In particular, a non-contact, audio-based sensor was used to capture the audible process dynamics during inertia friction welding of a dual-alloy component. The previous work employed a neural-network-based data mining technique to locate and identify features within the audio data that can be used to discriminate acceptable from unacceptable process behavior. This paper extends the previous work by providing a formal methodology for automatic, real-time, nondestructive, inspection of rotary friction welding.
Feasibility of Biodiesel as Microturbine Alternative Fuel Through Atomization Characteristics Study
Authors: Tan Ee Sann , Zulhairi Muhammad Anwar
Published: December 2013

The world is facing critical energy concern, in view of depleting fossil fuel reserves and increasing environment pollution. Biodiesel is a promising substitute that can reduce our dependence on fossil fuel. The application of biodiesel in microturbines is a new approach in the power generation industry. There are limited data at present on the potential of biodiesel in non-transportation sectors, where substantial energy and environment benefits exist. The objective of this paper is to study the feasibility of biodiesel to substitute conventional microtubine fuel through an atomization characteristics study in a fuel spray atomizer. Various blends of biodiesel derived from waste vegetable oil were tested experimentally in a fuel spray atomizer, to obtain main atomization characteristics such as Sauter Mean Diameter, spray angle and spray tip penetration. From the fuel properties analysis, it was found that the higher content of biodiesel gives higher viscosity, density and surface tension of the fuel. This will result in larger droplet size and longer spray length but smaller spray angle and spray width with clearer vortex shape of spray pattern in the atomization test experiment. Meanwhile, higher injection pressure during atomization testing process tend to break up fuel particles into smaller partition, which will subsequently produce larger spray angle and spray width but shorter spray length with denser spray pattern. The results of the experiment proved that biodiesel is a viable alternative fuel to gas turbine applications.
Alstom’s Reconditioning Technologies for Film Cooled Single Crystal (SX) Turbine Blading
Authors: Kissel Harald Peter , Shahin Hosam , Stankowski Alexander , Ambrosy Guenter , Bissig Hans
Published: December 2013

Increased availability, reliability and performance combined with reduced maintenance costs are key factors for the success of gas turbine users. Alstom reconditioning answers to this market demand by providing advanced and competitive repair techniques and an increasing broad reconditioning portfolio to its customers.

This paper focuses on the reconditioning of film cooled SX components used in the GT24 and GT26 fleet and the latest enabling technologies. The general reconditioning strategy is based on a thorough analysis of the accumulated field experience with SX parts and a controlled, step-wise introduction of new techniques. Taking advantage of the broad interdisciplinary OEM product and design know-how, as well as Alstom’s rich engineering experience in advanced reconditioning, state of the art reconditioning processes have been developed for different damage scenarios for components. This would include the most technically challenging SX “heavy” scope reconditioning.

This paper gives an overview about the reconditioning sequence for SX components and some of its key process steps. As an example, the crack braze repair process is described in detail and several novel SX welding techniques for crack repairs, blade tip and temperature controlled leading edge wall thickness restoration are shown. This covers different processes such as TIG welding or laser metal forming (LMF) of SX components.

During the last few years, highly automated production solutions and innovative production tools have been implemented, which enable high capacity and consistently high quality of reconditioning. After their successful validation and a limited phase of monitored production, these techniques are applied on rotating and stationary SX turbine parts. Validation criteria and the experience gained during the first years of commercial production and operation in the field will be presented.
Determination of Thermal Barrier Coatings Average Surface Temperature After Engine Operation for Lifetime Validation
Authors: Witz Grégoire , Bossmann Hans-Peter
Published: December 2013

Assessment of ex-service parts is important for power generation industry. It gives the opportunity to correlate part conditions to specific operating conditions like fuel used, local atmospheric conditions, operating regime, and temperature load. For assessment of thermal barrier coatings, one of the most valuable information is the local thermal condition. A method has been developed in Alstom, allowing determination of a thermal barrier coating average surface temperature after engine operation. It is based on the analysis of the phase composition of the thermal barrier coating by the acquisition of an X-Ray diffraction spectrum of the coating surface, and its analysis using Rietveld refinement. The method has been validated by comparing its outcome to thermal models and base metal temperature mapping data. It is used for assessment of combustor and turbine coatings with various purposes: determination of remnant coating life, building of lifing models, or determination of the coating degradation mechanisms under some specific operating conditions. Examples will be presented showing applications of this method.
Developing a Reduced-Order Model to Understand Non-Synchronous Vibration (NSV) in Turbomachinery
Authors: Clark Stephen T. , Kielb Robert E. , Hall Kenneth C.
Published: December 2013

This paper demonstrates the potential of using a multi-degree-of-freedom, traditional van der Pol oscillator to model Non-Synchronous Vibration (NSV) in turbomachinery. It is shown that the two main characteristics of NSV are captured by the reduced-order, van der Pol model. First, a stable limit cycle oscillation (LCO) is maintained for various conditions. Second, the lock-in phenomenon typical of NSV is captured for various fluid-structure frequency ratios. The results also show the maximum amplitude of the LCO occurs at an off-resonant condition, i.e., when the natural shedding frequency of the aerodynamic instability is not coincident with the natural modal frequency of the structure. This conclusion is especially relevant in preliminary design in industry because it suggests that design engineers cannot treat NSV as a normal Campbell-diagram crossing as they would for preliminary design for forced response; it is possible that by redesigning the blade, the response amplitude of the blade may actually be higher.

The goal of future research will be to identify values and significance of the coupling parameters used in the van der Pol model, to match these coefficients with confirmed instances of experimental NSV, and to develop a preliminary design tool that engineers can use to better design turbomachinery for NSV. Proper Orthogonal Decomposition (POD) CFD techniques and coefficient tuning from experimental instances of NSV have been considered to identify the unknown coupling coefficients in the van der Pol model. Both the modeling of experimental NSV and preliminary design development will occur in future research.
Financial Considerations of Using Pumped Hydroelectric Storage to Increase the Penetration of Wind and Solar Generation
Authors: Richards S. , Perez-Blanco H.
Published: December 2013

Renewable power production is both variable and difficult to forecast accurately. These traits can make its integration into an electric grid problematic. But because its “fuel” is free, it makes economic sense to utilize renewable energy whenever it is available. When a power grid is unable to accommodate low marginal cost renewable energy due to a generator fleet that lacks sufficient flexibility, the energy is usually wasted and dispatchable fossil fuel generators are utilized instead. However, if a pumped hydroelectric storage (PHS, see the glossary for definitions of select terms) facility is used to time shift the renewable power production, the energy is transformed into a dispatchable resource. Because of this dispatchability, the power can be sold as “firm” generation which typically gets a higher price on the wholesale electricity market. This paper will address the financial aspects of using PHS to firm and time shift the inherently variable wind and solar power generation in the Mid-Atlantic States.

The benefits that a PHS facility can offer to renewable power generators are many, but the biggest drawback to doing so is the high capital cost of PHS. In order to study the revenue streams of both PHS facilities and renewable power generators a computer model with one minute granularity was constructed. Electricity demand, power prices and wind power production were obtained from PJM’s website for the year 2010. The NREL program PVWatts v.1 was used to generate the simulated solar power production which was combined with the PJM data and used as input to the model. Currently, various PHS configurations are being tested in order to determine their effects on the profits of the PHS facility and the profits of renewable generators. Preliminary results show that the relationship between PHS owners and renewable power generators could be beneficial for both parties. The extents of the financial benefits are largely determined by the dynamics of the applicable wholesale electricity market, the accuracy of the power production forecast for renewable generators, the power capacity, the energy capacity and the round trip efficiency of the PHS facility.
Erosion Resistance of Titania Co-Doped Yttria Stabilized Zirconia
Authors: O’Brien Adam , Huang Xiao , Yang Q.
Published: December 2013

The standard yttria-stabilized zirconia (YSZ) has been used as thermal barrier coatings (TBCs) in the hot sections of gas turbine engines for several decades. To achieve further improvement to the thermal insulation capability of current TBCs, doping of alternative oxides to zirconia or co-doping of oxides to YSZ has been employed. In our previous study, it has been shown that doping of 7YSZ with titania (TiO2) reduces thermal conductivity of 7YSZ substantially. As TBCs are susceptible to various failure mechanisms, in this study the erosion resistance of TiYSZ at high impingement speed and angle is evaluated along with measurements of hardness (H) and elastic modulus (E). Specimens with 5 different TiO2 doping amounts (5%, 7.5%, 10%, 12.5% and 15%) are fabricated using plasma spraying and high temperature sintering. The erosion test results show that sample with 5% TiO2 (5TiYSZ) suffers the most erosion damage at high impingement angle due to brittle fracture while 10-15TiYSZ samples exhibit less brittle erosion damage which leads to lower erosion rates under the same test condition. When comparing the erosion rates (defined as the loss of sample mass per mass unit of abrasive particles) to the hardness values, they were found to follow the same trend. The addition of TiO2 (10–15 wt%) had the effect of reducing the erosion rate of 7YSZ at high impingement angle.
Supercritical Carbon Dioxide Brayton Power Cycle Development Overview
Authors: Kimball Kenneth J. , Clementoni Eric M.
Published: December 2013

The Knolls Atomic Power Laboratory (KAPL) and Bettis Atomic Power Laboratory are testing a supercritical carbon dioxide (S-CO2) Brayton power cycle system. The 100 kWe Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator using S-CO2 as the working fluid. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. The IST design includes a comprehensive instrumentation and control system incorporating results of turbomachinery operational testing performed at Barber Nichols Inc (BNI) in the Sandia National Laboratory’s DOE test loop. A detailed dynamic performance model was used both to predict IST performance and to evaluate the testing completed at BNI. The IST construction was completed in mid 2011 and is currently undergoing shakedown testing. Results of testing completed to date and future testing plans will be summarized.
Development of Design Method for Supersonic Turbine Aerofoils Near the Tip of Long Blades in Steam Turbines: Part 1—Overall Configuration
Authors: Senoo Shigeki
Published: December 2013

The purpose of this paper is development of the design method for supersonic turbine aerofoils. In particular, a design method is established for four fundamental parameters which determine the overall configuration of the aerofoils: inlet angle, outlet angle, pitch-to-chord ratio, and stagger angle.

The developed design method is constructed as follows. Three parameters of a velocity triangle, the inlet flow angle, inflow Mach number and pressure ratio, are selected as predetermined design parameters. The inlet angle is coincident with the inlet flow angle. The outlet angle is formulated as a function of the three design parameters using aerodynamic theory. An allowable design space between the pitch-to-chord ratio and the stagger angle is clarified by formulating three geometrical constraints to accelerate supersonic flow smoothly. The three geometrical constraints are the inlet and outlet flow passage areas derived from the design parameters and the no-inflection-point condition on the aerofoil surface. Good performance of supersonic turbine aerofoils designed by the developed method is confirmed using computational fluid dynamics. There is no strong shock wave.

When there is no solution in the theoretical allowable design space because of the large pitch-to-chord ratio required for low centrifugal stress, the following two methods enable the feasible design space to be enlarged without a large increase in the energy loss. One is to ease the restriction of the outlet flow passage area. The other is to increase the outlet flow angle of the pressure surface by about 10 deg in the axial direction from the theoretical angle. Their effectiveness is also validated by computational fluid dynamics.
Multidisciplinary Design Optimization of a Mixed Flow Turbine Wheel
Authors: Roclawski Harald , Böhle Martin , Gugau Marc
Published: December 2013

Designing turbine wheels for automotive turbochargers one is faced with a multidisciplinary design problem with many input and output parameters. Especially in the automotive industry short development cycles for high quality products in a competitive environment are daily routine.

For meeting these requirements optimization algorithms can be a powerful tool in the design process. This paper presents the multidisciplinary optimization of an automotive mixed flow turbine wheel used in a 4 cylinder 1.6 l spark ignition engine. Before describing the optimization workflow in detail, the requirements for turbines operating in an automotive environment under pulsating flow conditions and during an engine load step are discussed. From there objectives for a multidisciplinary optimization are derived.

The turbine wheel is optimized with respect to maximizing efficiency in two design points and minimizing its moment of inertia. For the optimization process, an algorithm based on evolution theory is used. As constraints, the operating points are fixed and the natural frequencies are limited to ensure the mechanical strength of the turbine. To speed up the optimization process meta models based on neural networks are applied. Three designs of the Pareto frontier are chosen and their characteristics are discussed. Using statistical methods, the interaction of the input variables and their impact on turbine performance are presented.
Electric Turbo Assist as an Enabler for Engine Downspeeding
Authors: Costall Aaron W. , Ivanov Radoslav , Langley Thomas P. F.
Published: December 2013

Electric Turbo Assist (ETA) is a novel air system technology that provides an extra degree of freedom in engine-turbocharger matching for optimal system performance and emissions. This paper presents simulation results from a research project to develop and demonstrate ETA, an integrated turbocharger-motor/generator, for a particular off-road machine duty cycle. Engine cycle simulation tools have been employed to investigate the potential of ETA to reduce fuel consumption through a combined downspeeding and exhaust energy regeneration strategy while meeting the required emissions levels and maintaining the desired engine response. Results show that ETA enables a flexible air system that can meet and even exceed the required air-fuel ratio and exhaust gas recirculation targets when the engine is downspeeded, while providing a useful fuel saving over the non-ETA baseline engine calibration.
A Novel Optical Technique for Measuring the Coefficient of Restitution of Microparticle Impacts in a Forced Flowfield
Authors: Reagle C. J. , Delimont J. M. , Ng W. F. , Ekkad S. V. , Rajendran V. P.
Published: December 2013

Erosion and deposition in gas turbine engines are functions of particle/wall interactions and Coefficient of Restitution (COR) is a fundamental property of these interactions. COR depends on impact velocity, angle of impact, temperature, particle composition, and wall material. The current study attempts to characterize the fundamental behavior of sand at different impact angles. A PIV system is used in the Virginia Tech Aerothermal Rig to measure velocity trajectories of microparticles. A novel method is used that solves for impact velocity in a forced flowfield by numerical methods. Two sizes of Arizona Test Dust and one of Glass beads are impacted into a 304 Stainless Steel coupon. Free jet velocity is 27m/s at room temperature. Impact angle varies from almost 90 to 25 degrees depending on particle. Mean results compare favorably with trends established in literature. This utilization of this technique to measure COR of microparticle sand will help develop a computational model and serve as a baseline for further measurements at elevated, engine representative air and wall temperatures.
Theoretical and Experimental Investigation of Force Estimation Errors Using Active Magnetic Bearings With Embedded Hall Sensors
Authors: Voigt Andreas Jauernik , Santos Ilmar F.
Published: December 2013

This paper gives an original theoretical and experimental contribution to the issue of reducing force estimation errors, which arise when applying Active Magnetic Bearings (AMBs) with pole embedded Hall sensors for force quantification purposes. Motivated by the prospect of increasing the usability of AMBs by embedding Hall sensors instead of mounting these directly on the pole surfaces, force estimation errors are investigated both numerically and experimentally. A linearized version of the conventionally applied quadratic correspondence between measured Hall voltage and applied AMB force is suggested and investigated. A finite element (FE) model is constructed to study force error behavior as a function of rotor offset. The investigation confirms that the magnitude of the force error is dependent on how well the rotor is centered in the AMB. Furthermore, below a rotor offset corresponding to ∼20% of the nominal air gap the force estimation error is found to be reduced by the linearized force equation as compared to the quadratic force equation, which is supported by experimental results. Additionally the FE model is employed in a comparative study of the force estimation error behavior for pole embedded and pole surface mounted Hall sensors. It is shown that in a given range of bias currents and rotor offsets, pole embedded and surface mounted Hall sensors perform equally well for the four pole heteropolar flux-split radial AMB under investigation. Furthermore, frequency dependence of the Hall sensor sensitivity factors is investigated, and found to be non-existing, hence static calibration of Hall sensors is sufficient, even for dynamic testing purposes.
Metal Frame Reinforced Ceramic Matrix Composite for High Temperature Applications
Authors: Kibsey Mitch , Mohammadi Teymoor , Huang Xiao , Kearsey Rick
Published: December 2013

The design, fabrication and preliminary assessment of novel metal reinforced ceramic matrix composite (CMC) materials are reported in this study. The design is based on the assumption that the metallic reinforcing structure can increase the work of fracture through the action of wire pullout, crack deflection and plastic deformation. In particular, the current CMC is composed of a molybdenum wire structure within a 7.5 wt% yttria-stabilized zirconia (7YSZ) ceramic matrix (Mo/YSZ). A unique jig is designed to assist the fabrication of the Mo mesh. Subsequently a NiCrAlY bond coat and finally a 7YSZ matrix are applied to the Mo mesh structure using a plasma spray technique. The as-fabricated and heat treated Mo/YSZ are subjected to impact and 3-point bend tests. The impact testing results show that heat treatment after spraying increases the impact energy possibly due to the improved bonding between Mo, NiCrAlY and 7YSZ. During 3-point bend testing, the incorporation of Mo mesh in 7YSZ increases the load at yield point, the peak load and the displacement to failure. After isothermal and cyclic oxidation tests at 1050°C for 330 hours, the Mo/YSZ CMC is examined under optical and scanning electron microscopes (SEM). The results show that the NiCrAlY bond coat delaminates from the Mo wire and also forms radial cracks during the spraying process. It is for this reason that the Mo wire suffers from rapid oxidization during isothermal and cyclic oxidation tests, causing separation of the reinforcement from the 7YSZ matrix. Future improvement to the current process will be to select and deposit a more effective oxidation resistant coating on the Mo wire in order to allow the metal frame-reinforced CMC concept to achieve the desired chemical and mechanical properties at high temperatures.
Redesigning the Auxiliary Power Unit Bleed Air Venturi
Authors: Dick Adam , Diamond Peter
Published: December 2013

This paper examines the analysis of re-designing the Auxiliary Power Unit (APU) bleed air spool piece used on the Landing Craft, Air Cushion (LCAC). The APU supplies bleed air for main engine (ME) starting, anti-icing of the propeller shrouds during cold weather conditions and anti-icing of the filtration system that supplies both ME compartment cooling air and the APU gas turbine combustion air. An air-blast cockpit windshield cleaning system is also powered by APU bleed air. A spool piece is a venturi whose function is to limit a specific amount of airflow as it passes through a system. The current spool piece venturi dimensions allow an excess in APU bleed air to on-craft components, resulting in an exhaust gas temperature (EGT) over-temp in the gas turbine power producer. Such operating conditions occur during cold weather testing, when port and starboard propeller shroud anti-ice systems and APU combustion air/main engine compartment cooling air anti-ice systems are operating. In order to rectify this issue, a model analysis was created, determining the proper dimension of the spool piece venturi. Because spool piece venturies have been implemented fleet wide, it was a priority to reduce fabrication expenses of new materials. To best achieve this, the analysis will determine the size of a plain venturi that can be installed within the existing spool pieces. Referring to engine specifications, APU bleed air was limited to a certain flow rate. However, anti-ice components also required a specific mass flow rate in order to operate properly. It is within these boundaries that the proper diameter of the venturi was determined. This issue further expands upon the analysis of thermal testing, inlet and outlet pressures and the mass flow rate of the new venturi dimension.
Scaling Small-Scale Wind Turbines for Wind Tunnel Testing
Authors: Burdett Timothy A. , Van Treuren Kenneth W.
Published: December 2013

Wind tunnel testing of wind turbines can provide valuable insights into wind turbine performance and provides a simple process to test and improve existing designs. However, the scale of most wind turbines is significantly larger than most existing wind tunnels, thus, the scaling required for testing in a typical wind tunnel presents multiple challenges. When wind turbines are scaled, often only geometric similarity and tip speed ratio matching are employed. Scaling in this manner can result in impractical rotational velocities. For wind tunnel tests that involve Reynolds numbers less than approximately 500,000, Reynolds number matching is necessary. When including Reynolds number matching in the scaling process, keeping rotational velocities realistic becomes even more challenging and preventing impractical freestream velocities becomes difficult. Turbine models of 0.5, 0.4, and 0.3 m diameter, resulting in wind tunnel blockages up to 52.8%, were tested in order to demonstrate scaling using Reynolds number matching and to validate blockage corrections found in the literature. Reynolds numbers over the blades ranged from 20,000 to 150,000 and the tip speed ratio ranged from 3 to 4 at the maximum power point for each wind speed tested.
Multistage Coupling of Eight Mistuned Bladed Disk on a Solid Shaft: Part 1—Free Vibration Analysis
Authors: Rzadkowski Romuald , Maurin Artur
Published: December 2013

Considered here was the effect of multistage coupling on the dynamics of a rotor consisting of eight mistuned bladed discs on a solid shaft. Each bladed disc had a different number of rotor blades. Free vibrations were examined using finite element representations of rotating single blades, bladed discs, and the entire rotor. In this study the global rotating mode shapes of eight flexible mistuned bladed discs on shaft assemblies were calculated, taking into account rotational effects such as centrifugal stiffening. The thus obtained natural frequencies of the blade, shaft, bladed disc and entire shaft with discs were carefully examined to discover resonance conditions and coupling effects. This study found that mistuned systems cause far more intensive multistage coupling than tuned ones. The greater the mistuning, the more intense the multistage coupling.
Influence of Mesh Density and Turbulence Models on 2D Viscous Flutter in 11th Standard Configuration
Authors: Pajak Aleksandra , Rzadkowski Romuald
Published: December 2013

In this study, numerical simulations of 2D viscous flutter were performed and compared with the available experimental results for different mesh density and different turbulence models. The calculations were carried out for bending oscillations of the cascade known as the Eleventh Standard Configuration. The ANSYS CFX v.12.1 code with SST, SA, k-ω turbulence models was used for calculations with various values of the inter-blade phase angle. Three moving H-O grids were used. Comparison of the calculated and the experimental results for the Eleventh Standard Configurations for the IBPA = 180 deg has shown good quantitative and qualitative agreement for local performances (unsteady pressure amplitude and phase distribution). For the IBPA = 90 and −90 deg the results are correct only in terms of amplitude. The phase distribution showed large deviations. The effect of various grids as well as SST, Spalart Allmaras and k-ω turbulence models was not significant in the subsonic case, but it turned out to be very noticeable in the transonic case.
A Metal Mesh Foil Bearing and a Bump-Type Foil Bearing: Comparison of Performance for Two Similar Size Gas Bearings
Authors: San Andrés Luis , Chirathadam Thomas Abraham
Published: December 2013

Gas bearings in oil-free microturbomachinery for gas process applications and power generation (< 400 kW) must be reliable and inexpensive, ensuring low drag power and thermal stability. Bump-type foil bearings (B-FBs) and overleaf-type foil bearings are in use in specialized applications, though their development-time (design and prototyping), exotic materials, and excessive manufacturing cost still prevent their widespread usage. Metal mesh foil bearings (MMFBs), on the other hand, are an inexpensive alternative that uses common materials and no restrictions on intellectual property. Laboratory testing shows that prototype MMFBs perform similarly as typical BFBs but offering significantly larger damping to dissipate mechanical energy due to rotor vibrations. This paper details a one-to-one comparison of the static and dynamic forced performance characteristics of a MMFB against a BFB of similar size and showcases the advantages and disadvantages of MMFBs. The bearings for comparison are a Generation I BFB and a MMFB, both with a slenderness ratio L/D = 1.04. Measurements of rotor lift-off speed and drag friction at start-up and airborne conditions were conducted for rotor speeds to 70 krpm and under identical specific loads (W/LD = 0.06 to 0.26 bar). Static load versus bearing elastic deflection tests evidence a typical hardening nonlinearity with mechanical hysteresis; the MMFB showing two to three times more material damping than the BFB. The MMFB exhibits larger drag torques during rotor start-up and shut-down tests though bearing lift-off happens at lower rotor speeds (∼15 krpm). As the rotor becomes airborne, both bearings offer very low drag friction coefficients, ∼0.03 for the MMFB and ∼0.04 for the BFB in the speed range 20–40 krpm. With the bearings floating on a journal spinning at 50 krpm, the MMFB dynamic direct force coefficients show little frequency dependency, while the BFB stiffness and damping increases with frequency (200–400 Hz). The BFB has a much larger stiffness and viscous damping coefficients than the MMFB. However, the MMFB material loss factor is at least twice as large as that in the BFB. The experiments show the MMFB, when compared to the BFB, has a lower drag power and earlier lift-off speed, and with dynamic force coefficients having a lesser dependency on whirl frequency excitation.