bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementation of NICE guidance on urinary tract infections in children in primary and secondary care
Authors: Platt Caroline , Larcombe James , Dudley Jan , McNulty Cliodna , Banerjee Jaydip , Gyoffry Gita , Pike Katie , Jadresic Lyda
Published: February 2015

Aim

To audit compliance with the 2007 National Institute of Clinical Excellence guidelines on the management of urinary tract infection in children under the age of 16 years across primary and secondary care services in England.

Methods

A retrospective multisite audit of 10 general practice, 3 paediatric, 2 paediatric emergency and 2 emergency general units. Four distinct geographical areas were represented. Data were collected between 1 January 2010 and 31 December 2010. Six criteria were audited, which focused on the following: improving the rate of diagnosis, management of the very young child with UTI and selection of children for imaging.

Results

A total of 1149 children were audited (682 from primary care and 467 from secondary care). Overall compliance was as follows: criterion 1: 28%; criterion 2: 68%; criterion 3: 89%; criterion 4: 43%; criterion 5 (comprising 12 subcriteria): 13% and for criterion 6: 45%.

Conclusion

The results indicate significant shortcomings in the implementation of NICE guidance on childhood UTI in England. The guidance is complex and this makes its implementation challenging. It was difficult to identify children presenting with nonspecific fever from clinical data systems. Adequate IT systems throughout the NHS are a key step to improving implementation of this and other NICE guidance.
Endocrine care of transpeople part I. A review of cross‐sex hormonal treatments, outcomes and adverse effects in transmen
Authors: Meriggiola Maria Cristina , Gava Giulia
Published: February 2015

Gender dysphoria (GD) is characterized by discomfort with the assigned or birth gender and the urge to live as a member of the desired sex. The goal of medical and surgical treatment is to improve the well‐being and quality of life of transpeople. The acquisition of phenotypic features of the desired gender requires the use of cross‐sex hormonal therapy (CHT). Adult transmen are treated with testosterone to induce virilization. In adolescents with severe and persistent GD, consideration can be given to arresting puberty at Tanner Stage II and if dysphoria persists, CHT is generally started after 16 years of age. Currently available short‐ and long‐term safety studies suggest that CHT is reasonably safe in transmen. Monitoring of transmen should be more frequent during the first year of cross‐sex hormone administration reducing to once or twice per year thereafter. Long‐term monitoring after sex reassignment surgery (SRS) includes annual check‐ups as are carried out for natal hypogonadal men. In elderly transmen, special attention should be paid to haematocrit in particular. Screening for breast and cervical cancer should be continued in transmen not undergoing SRS.
Global invasion history of the Mediterranean recluse spider: a concordance with human expansion
Authors: Luo Yufa , Li Shuqiang
Published: February 2015

The dispersal of modern humans from their African origins to the rest of the occupied world is a topic of lively debate centering principally on single versus multiple dispersals. The Mediterranean recluse spider Loxosceles rufescens, a significant pest, has gained much of its current distribution through commensalism with humans. Therefore, the matrilineal history of this spider should reflect dispersal patterns of human females. Here, an assessment of genetic variation at mitochondrial markers in 347 colonies of L. rufescens from 104 geographic sites worldwide reveals a north African origin of the global populations of L. rufescens. This involves at least three separate events among which two involve coincidental dispersals, including one to north Africa, Europe, Asia, North America, and Australia and the other to north Africa, Europe, and Asia only. North African L. rufescens appear to have expanded initially into Israel and subsequently spread into Greece, where a subset of these populations went eastward into Iran and southeastern Asia. This corresponds to the modern human southern dispersal theory. Chinese populations appear to have expanded approximately 42 710–46 008 yr ago. The initial split between the Greek and Chinese populations dates to 41 412–44 444 yr ago, which coincides with the expansion of modern humans into Southeast and East Asia. Thus, the matrilineal history of Asian L. rufescens tracks the history of human dispersals over tens of thousands of years.
UV radiation induces CXCL5 expression in human skin
Authors: Reichert Olga , Kolbe Ludger , Terstegen Lara , Staeb Franz , Wenck Horst , Schmelz Martin , Genth Harald , Kaever Volkhard , Roggenkamp Dennis , Neufang Gitta
Published: February 2015

CXCL5 has recently been identified as a mediator of UVB‐induced pain in rodents. To compare and to extend previous knowledge of cutaneous CXCL5 regulation, we performed a comprehensive study on the effects of UV radiation on CXCL5 regulation in human skin. Our results show a dose‐dependent increase in CXCL5 protein in human skin after UV radiation. CXCL5 can be released by different cell types in the skin. We presumed that, in addition to immune cells, non‐immune skin cells also contribute to UV‐induced increase in CXCL5 protein. Analysis of monocultured dermal fibroblasts and keratinocytes revealed that only fibroblasts but not keratinocytes displayed up regulated CXCL5 levels after UV stimulation. Whereas UV treatment of human skin equivalents, induced epidermal CXCL5 mRNA and protein expression. Up regulation of epidermal CXCL5 was independent of keratinocyte differentiation and keratinocyte‐keratinocyte interactions in epidermal layers. Our findings provide first evidence on the release of CXCL5 in UV‐radiated human skin and the essential role of fibroblast‐keratinocyte interaction in the regulation of epidermal CXCL5.
High Precision Sr‐Nd‐Hf‐Pb Isotopic Compositions of USGS Reference Material BCR‐2
Authors: Jweda Jason , Bolge Louise , Class Cornelia , Goldstein Steven L.
Published: February 2015

The Lamont‐Doherty Earth Observatory radiogenic isotope group has been systematically measuring Sr‐Nd‐Pb‐Hf isotopes of USGS reference material BCR‐2 (Columbia River Basalt 2), as a chemical processing and instrumental quality control monitor for isotopic measurements. BCR‐2 is now a widely used geochemical inter‐laboratory reference material (RM), with its predecessor BCR‐1 no longer available. Recognising that precise and accurate data on RMs is important for ensuring analytical quality and for comparing data between different laboratories, we present a compilation of multiple digestions and analyses made on BCR‐2 during the first author's dissertation research. The best estimates of Sr, Nd and Hf isotope ratios and measurement reproducibilities, after filtering at the 2s level for outliers, were 87Sr/86Sr = 0.705000 ± 11 (2s, 16 ppm, n = 21, sixteen digestions, one outlier), 143Nd/144Nd = 0.512637 ± 13 (2s, 25 ppm, n = 27, thirteen digestions, one outlier) and 176Hf/177Hf = 0.282866 ± 11 (2s, 39 ppm, n = 25, thirteen digestions, no outliers). Mean Nd and Hf values were within error of those reported by Weis et al. (2006, 2007) in their studies of RMs; mean Sr values were just outside the 2s uncertainty range of both laboratories. Moreover, a survey of published Sr‐Nd‐Hf data shows that our results fall within the range of reported values, but with a smaller variability. Our Pb isotope results on acid leached BCR‐2 aliquots (n = 26, twelve digestions, two outliers) were 206Pb/204Pb = 18.8029 ± 10 (2s, 55 ppm), 207Pb/204Pb = 15.6239 ± 8 (2s, 52 ppm), 208Pb/204Pb = 38.8287 ± 25 (2s, 63 ppm). We confirm that unleached BCR‐2 powder is contaminated with Pb, and that sufficient leaching prior to digestion is required to achieve accurate values for the uncontaminated Pb isotopic compositions.
Children's night waking among toddlers: relationships with mothers' and fathers' parenting approaches and children's behavioural difficulties
Authors: Zaidman‐Zait Anat , Hall Wendy A.
Published: February 2015

Aims

To explore associations between children's sleep problems, and behavioural difficulties and parenting approaches.

Background

Children commonly have problematic night waking; however, relationships between parenting cognitions and behaviours and children's sleep problems are rarely examined.

Design

Longitudinal children's cohort study from 5–29 months post birth.

Methods

Data were taken from the Quebec Longitudinal Study of Child Development (1998–2007) at three phases: 5, 17 and 29 months of age. Thousand four hundred and eighty‐seven families were included in our study based on: participation from phase 1 (5‐months old), both parents' reports on parenting cognitions/behaviours and child behavioural difficulties at 29 months, and mothers' reports of children's sleep at 29 months. In 2013, we conducted repeated measures anovas and manovas including children's gender.

Results

Extended night‐time waking patterns (wakes of ≥20 minutes) were associated with mothers' and fathers' lower sense of parenting impact and higher overprotectiveness and mothers' lower self‐efficacy and higher coerciveness for 29‐month‐old children. In the extended waking group, mothers consistently reported lower self‐efficacy, higher overprotectiveness and lower parenting impact at 5, 17 and 29 months. For those children, fathers were only more overprotective at 5 and 29 months. Regarding 29‐month‐old children's behaviour, children in the extended night waking group had highest scores on externalizing and internalizing behaviours. Girls had higher scores on shyness/inhibition and boys had higher scores on aggression/hyperactivity.

Conclusion

Mothers' and fathers' parenting cognitions and behaviours are affected by 29‐month‐old children's night waking patterns and night waking patterns are associated with children's behavioural problems.
Assessment of Flood Vulnerability Based on CMIP5 Climate Projections in South Korea
Authors: Park Jihoon , Kang Moon Seong , Song Inhong
Published: February 2015

The objective of this article was to assess flood vulnerability based on the representative concentration pathways (RCP) scenarios at city and county levels. A quantile mapping method was adopted to correct bias that is inherent in climate change scenarios. A series of proxy variables related to climate exposure, sensitivity, and adaptive capacity were chosen to assess flood vulnerability. Proxy variables were standardized using the Z‐score method. Principal component analysis was carried out to calculate the weighting of proxy variables. The study area was the Korean peninsula. The spatial resolution was on a city and county basis and the temporal resolution was 1990s, 2025s, 2055s, and 2085s (divided into 1976‐2005, 2011‐2040, 2041‐2070, and 2071‐2100). In the spatial comparison, we found that the areas with high‐level flood vulnerability increased over time in the central region, including metropolitan areas, and near the southern coast. In the temporal comparison, we found that the RCP4.5 scenario showed a tendency to increase steadily and the RCP8.5 scenario showed a tendency to decrease in the 2055s slightly and increase again in the 2085s. The study findings may provide useful data for the determination of priority for countermeasure development, though robustness of these findings with additional future projections should be established.
A Comparison of the J‐1 Visa Waiver and Loan Repayment Programs in the Recruitment and Retention of Physicians in Rural Nebraska
Authors: Opoku Samuel T. , Apenteng Bettye A. , Lin Ge , Chen Li‐Wu , Palm David , Rauner Thomas
Published: February 2015

Purpose

There is a dearth of literature evaluating the effectiveness of programs aimed at recruiting and retaining physicians in rural Nebraska. Taking advantage of the Nebraska Health Professional Tracking System, this study attempts to comparatively assess the effectiveness of the J‐1 visa waiver and state loan repayment programs in the recruitment and retention of physicians in rural Nebraska.

Methods

A mixed methods approach was used. We tracked 240 physicians who enrolled in the J‐1 visa waiver and state loan repayment programs between 1996 and 2012 until 2013. In addition, key informant interviews were conducted to obtain perspectives on the recruitment and retention of physicians in rural Nebraska through the 2 programs.

Findings

Results from multilevel survival regression analysis indicated that physicians enrolled in the J‐1 visa waiver program were more likely to leave rural Nebraska when compared with those enrolled in the state loan repayment program. Participants in the qualitative study, however, cautioned against declaring one program as superior over the other, given that the 2 programs addressed different needs for different communities. In addition, results suggested that fostering the integration of physicians and their families into rural communities might be a way of enhancing retention, regardless of program.

Conclusion

The findings from this study highlight the complexity of recruitment and retention issues in rural Nebraska and suggest the need for more holistic and family‐centered approaches to addressing these issues.
Engineering of ribozymes with useful activities in the ancient RNA world
Authors: Müller Sabine
Published: February 2015

Evidence has been growing that an RNA world existed before DNA‐ and protein‐based life. In this regard, a longstanding research goal has been to develop functional RNAs capable of catalyzing numerous chemical reactions. Much effort has been undertaken in finding RNA enzymes that catalyze the replication of RNA molecules, including the enzymes themselves. This, however, is far from being resolved. Apart from replication, other functionalities that contribute to higher genetic complexity and extended functional space are of high relevance to RNA‐world scenarios. We have engineered a variety of hairpin ribozyme descendants possessing activity for RNA recombination, circularization, and oligomerization. Furthermore, we have developed ribozymes that can be regulated by external cofactors such as flavine mononucleotide (FMN), and we have designed a system for RNA‐catalyzed RNA aminoacylation as a possible path toward a transition from the RNA world to modern life.
Toxic Epidermal Necrolysis Triggered by Clobazam: A Case Report in a 13‐Year‐Old Girl
Authors: Dang Chuong D. , Beets‐Shay Linda , Kahn Estelle C.
Published: February 2015

We present a case of toxic epidermal necrolysis (TEN) triggered by clobazam in a 13‐year‐old girl who was subsequently treated with intravenous immunoglobulin. In December 2013 the U.S. Food and Drug Administration released a warning that clobazam might cause “serious skin reactions” such as Stevens–Johnson syndrome or TEN and approved label changes.
T‐Spot.TB outperforms tuberculin skin test in predicting development of active tuberculosis among household contacts
Authors: Leung Chi Chiu , Yam Wing Cheong , Ho Pak Leung , Yew Wing Wai , Chan Chi Kuen , Law Wing Sze , Lee Shuk Nor , Chang Kwok Chiu , Tai Lai Bun , Tam Cheuk Ming
Published: February 2015

Background and Objective

In Hong Kong, neonatal Bacillus Calmette–Guerin (BCG) vaccination is practiced with 99% coverage. This study was to compare the performance of T‐Spot.TB and tuberculin skin test (TST) in predicting tuberculosis (TB) among household contacts.

Methods

From 1 March 2006 to 31 July 2010, 1049 asymptomatic household contacts of smear‐positive patients were simultaneously tested with T‐Spot.TB and TST, and then followed for up to 5 years for development of TB. Attending clinicians and subjects were blinded to the results of T‐Spot.TB.

Results

T‐Spot.TB gave a significantly higher positive rate (32.7% vs 22.1%) and better association with exposure time than TST at the 15 mm cut‐off. Agreement between T‐Spot.TB and TST using cut‐offs of 5, 10 and 15 mm were relatively poor (kappa 0.25–0.41) irrespective of presence or absence of BCG scar. Only T‐Spot.TB positivity was negatively associated with BCG scar. Both T‐Spot.TB (incidence rate ratio between test‐positive and test‐negative subjects, IRR: 8.2) and TST (IRR: 4.1, 6.1 and 2.8, using cut‐offs of 5 mm, 10 mm and 15 mm, respectively) helped to predict TB. Using a TST cut‐off of 15 mm, 56% of future TB cases and 62.5% of bacteriologically confirmed cases were missed. Lowering the TST cut‐off to 10 mm or 5 mm could achieve sensitivity comparable with that of T‐Spot.TB, but at the expense of lower specificities, with more positive tests (thus requiring treatment) per case of TB predicted.

Conclusions

T‐Spot.TB outperformed TST in predicting TB among household contacts in a high‐income area with widespread BCG vaccination coverage.
Asset Decommissioning Risk Metrics for Floating Structures in the Gulf of Mexico
Authors: Kaiser Mark J.
Published: February 2015

Public companies in the United States are required to report standardized values of their proved reserves and asset retirement obligations on an annual basis. When compared, these two measures provide an aggregate indicator of corporate decommissioning risk but, because of their consolidated nature, cannot readily be decomposed at a more granular level. The purpose of this article is to introduce a decommissioning risk metric defined in terms of the ratio of the expected value of an asset's reserves to its expected cost of decommissioning. Asset decommissioning risk (ADR) is more difficult to compute than a consolidated corporate risk measure, but can be used to quantify the decommissioning risk of structures and to perform regional comparisons, and also provides market signals of future decommissioning activity. We formalize two risk metrics for decommissioning and apply the ADR metric to the deepwater Gulf of Mexico (GOM) floater inventory. Deepwater oil and gas structures are expensive to construct, and at the end of their useful life, will be expensive to decommission. The value of proved reserves for the 42 floating structures in the GOM circa January 2013 is estimated to range between $37 and $80 billion for future oil prices between 60 and 120 $/bbl, which is about 10 to 20 times greater than the estimated $4.3 billion to decommission the inventory. Eni's Allegheny and MC Offshore's Jolliet tension leg platforms have ADR metrics less than one and are approaching the end of their useful life. Application of the proposed metrics in the regulatory review of supplemental bonding requirements in the U.S. Outer Continental Shelf is suggested to complement the current suite of financial metrics employed.
Positive‐Themed Suicide Prevention Messages Delivered by Adolescent Peer Leaders: Proximal Impact on Classmates' Coping Attitudes and Perceptions of Adult Support
Authors: Petrova Mariya , Wyman Peter A. , Schmeelk‐Cone Karen , Pisani Anthony R.
Published: February 2015

Developing science‐based communication guidance and positive‐themed messages for suicide prevention are important priorities. Drawing on social learning and elaboration likelihood models, we designed and tested two positive‐focused presentations by high school peer leaders delivered in the context of a suicide prevention program (Sources of Strength). Thirty‐six classrooms in four schools (N = 706 students) were randomized to (1) peer leader modeling of healthy coping, (2) peer leader modeling plus audience involvement to identify trusted adults, or (3) control condition. Students' attitudes and norms were assessed by immediate post‐only assessments. Exposure to either presentation enhanced positive coping attitudes and perceptions of adult support. Students who reported suicide ideation in the past 12 months benefited more than nonsuicidal students. Beyond modeling alone, audience involvement modestly enhanced expectations of adult support, congruent with the elaboration likelihood model. Positive peer modeling is a promising alternative to communications focused on negative consequences and directives and may enhance social–interpersonal factors linked to reduced suicidal behaviors.
A new human leukocyte antigen class II allele, DRB1*09:12
Authors: Li J.‐P. , Li X.‐F. , Zhang X. , Lin F.‐Q. , Zhang K.‐L.
Published: February 2015

HLA‐DRB1*09:12 allele differs from HLA‐DRB1*09:01:02 by a single nucleotide substitution at codon 41 (AAG → AAC).
Identification of a novel HLA‐A*02:06:14 allele by polymerase chain reaction sequence‐based typing in a Chinese bone marrow donor
Authors: He J. , Chen N.‐Y. , Wang W. , Han Z.‐D. , Zhu F.‐M. , Lv H.‐J.
Published: February 2015

HLA*02:06:14 differs from HLA‐A*02:06:01 by a single nucleotide substitution G > A at position 246.
Endoscopie et conjecture locale raffinée de Gan–Gross–Prasad pour les groupes unitaires
Authors: Beuzart-Plessis R.
Published: February 2015

Under endoscopic assumptions about $L$-packets of unitary groups, we prove the local Gan–Gross–Prasad conjecture for tempered representations of unitary groups over $p$-adic fields. Roughly, this conjecture says that branching laws for $U(n-1)\subset U(n)$ can be computed using epsilon factors.
Laser Guidance for Repairing Gas Turbine Parts
Authors: Galel Zev , Hunt James L. , Unger Thomas H.
Published: February 2015

As a result of normal operating conditions, jet engine parts tend to distort. During repair, many of these parts require some form of selective cutting. Due to the differences between each individual part, automation such as CNC machining becomes complex. The need to map each individual part prior to machining has prohibited repair facilities from introducing sophisticated automation. This paper presents for the first time a novel method that addresses many problems related to selective material removal in Jet Engine repairs. Similar to a terrain-following cruise missile, a laser guided cutter is used to follow a selected datum surface. For example, in the case of Honeycomb Airseals, the thin laser beam penetrates through the honeycomb cell structure to follow the base metal. The method minimizes parent metal removal and under-minimum-wall condition. As a result, life potential of parts is extended, and repair costs are reduced. The ability to track a moving part and modify the cutting path automatically produces one more significant advantage: accurate set-up of a part on a machine is no longer critical. The method has applications in the repair of airseals, frames and cases, and airfoils.
Flow Field and Performance of a Centrifugal Compressor Rotor With Tandem Blades of Adjustable Geometry
Authors: Josuhn-Kadner Burkhard
Published: February 2015

A centrifugal compressor stage has been investigated mainly experimentally for aerodynamic stage optimization. The rotor consists of a separate inducer with 14 blades and an impeller with 28 blades. Both rotor components can be locked with each other at different circumferential positions thus, forming either a conventional splitter blade rotor or a tandem bladed rotor of adjustable geometry. The influence of the tandem blade geometry on the rotor and stage characteristics is studied in detail. Laser-2-Focus-System measurements were performed at nine locations all over the rotor taking three different circumferential inducer positions into account. The improvement with the tandem blade configuration on the rotor and stage characteristics is small but significant differences in the flow field of the two different impeller channels in the rear and exit part of the rotor are recognizable. The velocity differences of the jet/wake flow are reduced by using tandem blades which lead to a slight increased stage pressure ratio and surge margin.
Three-Dimensional Navier-Stokes Prediction of Heat Transfer With Film Cooling
Authors: Fougères J. M. , Helder R.
Published: February 2015

Three-dimensional Navier-Stokes calculations have been performed on various geometries in the presence of discrete-hole injection. The quality of the aerodynamic and thermal predictions of the flow is assessed by comparison to experiments.

The code used for the calculations is developed at ONERA and has previously been presented by various authors (Billonnet et al., 1992). It solves the unsteady set of three-dimensional Navier-Stokes equations, completed by a mixing-length turbulence model, using a finite volume technique.

The multi-domain approach of the code has facilitated the treatment of this type of geometry. The injection holes are discretized on cylindrical subdomains which overlap the mesh of the main flow.

Two applications of the code are presented in this paper. First, a calculation was performed on a row of hot jets injected into a flat plate turbulent boundary layer. Secondly, the code was tested on a plane nozzle guide vane grid with multiple injections. Heat transfer rates, temperature and velocity profiles are compared to experimental data.
Prediction of Film Cooling on Gas Turbine Airfoils
Authors: Garg Vijay K. , Gaugler Raymond E.
Published: February 2015

A three-dimensional Navier-Stokes analysis tool has been developed In order to study the effect of film cooling on the flow and heat transfer characteristics of actual turbine airfoils. An existing code (Amone et al., 1991) has been modified for the purpose. The code is an explicit, multigrid, ceil-centered, finite volume code with an algebraic turbulence model. Eigenvalue scaled artificial dissipation and variable-coefficient implicit residual smoothing are used with a full-multigrid technique. Moreover, Mayle’s transition criterion (Mayle, 1991) is used. The effects of film cooling have been incorporated into the code in the form of appropriate boundary conditions at the hole locations on the airfoil surface. Each hole exit is represented by several control volumes, thus providing an ability to study the effect of hole shape on the film-cooling characteristics. Comparison with mid-span experimental data for four and nine rows of cooling holes is fair. The computations, however, show a strong spanwise variation of the heat transfer coefficient on the airfoil surface, specially when the shower-head cooling holes are on.
Inverse Method for Turbomachine Blades Using Existing Time-Marching Techniques
Authors: Dang T. , Isgro V.
Published: February 2015

A newly-developed inverse method for the design of turbomachine blades using existing time-marching techniques for the numerical solutions of the unsteady Euler equations is proposed. In this inverse method, the pitch-averaged tangential velocity (or the blade loading) is the specified quantity, and the corresponding blade geometry is Iteratively sought after. The presence of the blades are represented by a periodic array of discrete body forces which are included in the equations of motion. A four-stage Runge-Kutta time-stepping scheme is used to march a finite-volume formulation, of the unsteady Euler equations to a steady-state solution. Modification of the blade geometry during this time marching process is achieved using the slip boundary conditions on the blade surfaces. This method is demonstrated for the design of infinitely-thin cascaded blades in the subsonic, transonic, and supersonic flow regimes. Results are validated using an Euler analysis method and are compared against those obtained using a similar inverse method. Excellent agreement in the results are obtained between these different approaches.
Computed Eccentricity Effects on Turbine Rim Seals at Engine Conditions With a Mainstream
Authors: Guo Zhou , Rhode David L. , Davis Fred M.
Published: February 2015

A previously verified axisymmetric Navier-Stokes computer code was extended for three-dimensional computation of eccentric rim seals of almost any configuration. All compressibility and thermal/momentum interaction effects are completely, included, and the temperature, pressure and Reynolds number of the mainstream, coolant stream and turbine wheel are fixed at actual engine conditions. Regardless of the seal eccentricity, both ingress and egress are found between θ = −30° and 100°. which encompasses the location of maximum radial clearance at θ = 0°. All other θ locations within the rim seal show only egress, as does the concentric basecase for all circumferential locations. Further, the maximum ingress occurs near θ = 30° for all eccentricities. This is found to produce a blade root/retainer temperature rise from the concentric case of 390 percent at 50 percent eccentricity and a 77 percent rise at 7.5 percent eccentricity. In addition, the nature of an increased eccentricity causing a decreased seal effectiveness is examined, along with the corresponding increase of cavity-averaged temperature.
Turbulence Measurements in a Heated, Concave Boundary Layer Under High Free-Stream Turbulence Conditions
Authors: Kestoras Michael D. , Simon Terrence W.
Published: February 2015

Turbulence measurements for both momentum and heat transfer are taken in a low-velocity, turbulent boundary layer growing naturally over a concave wall. The experiments are conducted with negligible streamwise acceleration and a nominal free-stream turbulence intensity of −8%. Comparisons are made with data taken in an earlier study in the same test facility but with a 0.6% free-stream turbulence intensity. Results show that elevated free-stream turbulence intensity enhances turbulence transport quantities like uv and vt in most of the boundary layer. In contrast to the low-turbulence cases, high levels of transport of momentum are measured outside the boundary layer. Stable, Görtler-like vortices, present in the flow under low-turbulence conditions, do not form when the free-stream turbulence intensity is elevated. Turbulent Prandtl numbers, Prt, within the log region of the boundary layer over the concave wall increase with streamwise distance to values as high as 1.2. Profiles of Prt suggest that the increase in momentum transport with increased free-stream turbulence intensity precedes the increase in heat transport. Distributions of near-wall mixing length for momentum remain unchanged on the concave wall when free-stream turbulence intensity is elevated. Both for this level of free-stream turbulence and for the lower level, mixing length distributions increase linearly with distance from the wall following the standard slope. However when free-stream turbulence intensity is elevated, this linear region extends farther into the boundary layer, indicating the emerging importance of larger eddies in the wake of the boundary layer with the high-turbulence free-stream. Because these eddies are damped by the wall, the influence of the wall grows with eddy size.
Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of 3D Inverse Design Method: Part 2 — Experimental Validation
Authors: Goto A. , Takemura T. , Zangeneh M.
Published: February 2015

In Part I of this paper, a mixed-flow pump impeller was designed by a fully three-dimensional inverse design method, aimed at suppressing the secondary flows on the blade suction surface. In this part, the internal flow fields of the impeller are investigated experimentally, using flow visualization and phase-locked measurements of the impeller exit flow, in order to validate the effects of secondary flow suppression. The flow fields are compared with those of a conventional impeller, and it is confirmed that the secondary flows on the blade suction surface are well suppressed and the uniformity of the exit flow fields is improved substantially, in both circumferential and spanwise directions. The effects of tip clearance and the number of blades for the inverse designed impeller are also investigated experimentally and numerically.
Active Vibration Control of Rotating Machinery With a Hybrid Piezo-Hydraulic Actuator System
Authors: Tang Punan , Palazzolo Alan B. , Kascak Albert F. , Montague Gerald T.
Published: February 2015

An integrated, compact piezo-hydraulic actuator system for active vibration was designed and developed with a primary application for gas turbine aircraft engines. Copper tube was chosen as the transmission line material for ease of assembly. Liquid plastic which meets incompressibility and low viscosity requirements was adjusted to provide optimal actuator performance. Variants of the liquid plastic have been prepared with desired properties between −40°F and 400° F. The effectiveness of this hybrid actuator for active vibration control (AVC) was demonstrated for suppressing critical speed vibration through two critical speeds for various levels of intentionally placed imbalance. A high accuracy closed loop simulation which combines both finite element and state space methods was applied for the closed loop unbalance response simulation with/without AVC. Good correlation between the simulation and test results was achieved.
Transonic Turbomachinery Calculations Using a Hybrid Structured-Unstructured Grid Method
Authors: Richardson Scott M.
Published: February 2015

A method is presented for solving the two-dimensional Navier-Stokes equations on a solution-adaptive grid of both structured and unstructured meshes. Flow near airfoil surfaces is modeled using an implicit finite difference algorithm on a structured O-type mesh. The flow equations in the blade passages are written in a cell-vertex finite volume formulation and are solved on an unstructured mesh using a Runge-Kutta explicit algorithm. Both the structured and unstructured grid also include solution dependent adaptation to allow resolution of flow features with a minimum of grid points. The structured mesh divides to locally add grid lines, while the unstructured mesh allows the addition or removal of individual cells. An overlapping interface region is used to conservatively communicate flow variable information between the two grids. The quasi-three-dimensional effects of streamtube contraction and radius change are included to allow calculation of modern turbomachine designs. A study is included to determine the effect on cacade parameters of inclusion of viscous terms in the solution of the flow equations in the unstructured domain. Quasi-three-dimensional computations of flow through a transonic compressor and turbine cascade are compared with experimental data.
A New Uprated Turbine for the GT8 and GT8C Gas Turbine Family
Authors: Harasgama S. P. , Kreitmeier F.
Published: February 2015

This paper describes the design of an uprated turbine for the GT8 gas turbine. The new turbine is installed in the GT8C gas turbine unit. The entire aero-thermal performance of the old turbine has been re-assessed and the new design improves upon the old unit by a 3.5% point increase in gas turbine efficiency. Additionally, the heat transfer and cooling of the turbine has been improved with the blading having more uniform thermal loading resulting in improved thermo-mechanical life-time. This has been achieved with better cooling technology whilst still maintaining the same cooling air mass flow. The paper describes the steps involved in the uprating.
Development of a 6 MW-Class High-Efficiency Gas Turbine M7A-01
Authors: Sugimoto T. , Ikesawa K. , Kajita S. , Karasawa W. , Kojima T. , Nagal K.
Published: February 2015

The M7A-01 gas turbine is a newly developed 6 MW class single-shaft machine. With its high simple-cycle efficiency and high exhaust gas temperature. it is particularly suited for use in electric power generation and co-generation applications.

An advanced high efficiency axial-flow compressor, six can-type combustors, and a high inlet temperature turbine has been adopted. This results in a high thermal efficiency of 31.5% at the gas turbine output shaft and a high overall thermal efficiency of co-generation system.

In addition, low NOx emissions from the combustors and a long service life permit long-term continuous operation under various environmental limitations.

The results of the full load shop test, accelerated cyclic endurance test and extra severity tests verified that the performance, the mechanical characteristics and the emission have satisfied the initial design goals.
Development of Centrifugal Compressor for 100 kW Automotive Ceramic Gas Turbine
Authors: Uchida Hiroshi , Shiraki Mutsuo , Bessho Akinobu , Yagi Yoichi
Published: February 2015

In Japan, a program of research and development of a 100 kW automotive ceramic gas turbine (CGT) has been carried out in the Petroleum Energy Center with active cooperation of petroleum, automobile and ceramics industries as well as other related industries. As a part of this research and development program, we have studied and developed a centrifugal compressor with variable inlet guide vanes for CGT engines. There has been a strong demand for a compressor with a high efficiency and a wide flow range. The compressor performance goals are an adiabatic efficiency of 81% and a surge margin of 8% under maximum power operating conditions.

This paper describes the methods for designing impellers, diffusers and variable inlet guide vanes, and presents the results of compressor performance tests. The test results reveal that the surge margin and compressor efficiency at partial load are improved by using inlet guide vanes.
Measurements of the Flow in an Idealized Turbine Tip Gap
Authors: Sjolander S. A. , Cao D.
Published: February 2015

To gain further insights into the details of the tip-gap flow in axial turbines, a test section has been constructed with a single, idealized, large-scale tip gap. The single “blade” forms a circular arc with 90 degrees of turning and has a constant thickness of 78 mm. For a plain, flat tip four clearances have been examined, varying from 0.292 to 0.667 of the blade thickness (corresponding to physical gap heights of 22.8 to 52.1 mm). The large proportions made it possible to obtain very detailed measurements inside the gap.

The paper discusses the structure of the gap flow in some detail. One new feature, involving multiple vortices on the tip, probably helps to explain the “burnout” which sometimes occurs on turbine tips near the pressure side. Quantitative results are presented for the static pressures, total pressures and velocity vectors through the gap. In addition, contraction coefficients for the flow at the separation bubble, discharge coefficients for the gap, and the gap losses have been extracted for comparison with the assumptions made in recent gap-flow models.
Maximum Power Point Characteristics of a Closed Brayton Cycle
Authors: Diao Zheng-Gang
Published: February 2015

The characteristics of a Closed Brayton Cycle at maximum power point is analyzed. The results are compared with the Curzon and Ahlborn efficiency. For endoreversible cycles, the CBC efficiency at maximum power point is the same as that of Curzon and Ahlborn. Dependences of maximum power are also analyzed in respect to temperature ratio and component losses.
Development of 300kW Class Ceramic Gas Turbine (CGT303)
Authors: Ohhashi Issel , Arakawa Sadao
Published: February 2015

CCT303 is a two-shaft regenerative ceramic gas turbine with rotary heat exchangers for the purpose of mobile power generator. It is also widely adaptable for industrial machinery and construction machinery as well. The development program of CGT303 is funded by New Energy and Industrial Technology Development Organization (NEDO).

The maximum output power of 300kW and thermal efficiency of 42% at TiT 1350C are the objectives of this development. The high TiT requires for the material of all gas passage components to use ceramics which are designed appropriately to keep sufficient strength by using sophisticated computer analysis.

Hot spin tests on ceramic turbine rotors and thermal shock tests on stationary ceramic components have been carried out to prove their strength. The paper covers the design concept of CGT303 and results of analysis.
The Advanced Gas Turbine Systems Research Program: A Model for Industry, University and Government Cooperation
Authors: Allen Roy P. , Michell Paul L.
Published: February 2015

An integral part of the U. S. Department of Energy’s Advanced Turbine Systems Program is the Industry/University consortium, formed to strengthen the gas turbine technology base among American universities. The Advanced Gas Turbine Systems Research program is sponsored by DOE, directed by industry leaders, and the universities conduct the research. This close alliance assures that the research is accomplished in a timely fashion, in areas critical to industry needs.

In the past year and a half the consortium has been organized, members solicited, Requests For Proposals issued, and contracts awarded. Some 60 universities in the U. S. are participating. This paper will discuss how the program was initiated, how it functions, and will review some of the interesting research that is under way in support of the overall ATS goals.
Determining Failure Laws for Ceramic Materials
Authors: Smart John , Fok Siu L.
Published: February 2015

For determining the failure probability of ceramic components in a varying stress field, there are many theories which are based on the Weibull “weakest-link” ideas. However, the difference between the predictions for many stress systems is small and because of the scatter in the failure loads for ceramic materials and the inevitable experimental errors, it has been difficult to decide which is most suitable.

In this paper, a testing regime is described which spreads the predictions from the various theories to allow the most suitable theory for a given material to be chosen. This will give more confidence when designing with ceramics.

Tests are also described on a reactor grade graphite and it is shown that of the theories examined the maximum non-coplanar strain energy release rate is the most suitable criterion although the results indicate that current ‘weakest-link’ ideas may not be suitable to describe all loading situations. Reasons for this are discussed.
Computation of Unsteady Nozzle Flow due to Fluctuating Back-Pressure Using Euler Equations
Authors: Gerolymos Georg A. , Bréus Jean-Pascal
Published: February 2015

In this paper a numerical method is developed for the integration of the unsteady two-dimensional Euler equations using a third-order upwind-biased scheme with Van Leer flux-vector-splitting and Von Albada limiters, with MUSCL space-discretization, and an explicit two-stage Runge-Kutta time-integration procedure. The method is applied to the numerical computation of flows in a transonic nozzle with fluctuating back-pressure, and compared with available experimental data. The effects of frequency and amplitude on the shock-wave response are studied in detail. Despite the use of an inviscid flow model the unsteady pressures are quite satisfactorily predicted over the range of frequencies studied. The numerical method is then used to study the effect of the back-pressure fluctuation amplitude on the shock-wave oscillation. At large amplitudes the flowfield response to back-pressure fluctuation is essentially nonlinear.
Heat Transfer to Rotating Turbine Blades in a Flow Undisturbed by Wakes
Authors: Garside T. , Moss R. W. , Ainsworth R. W. , Dancer S. N. , Rose M. G.
Published: February 2015

The flow over the high pressure blades of a gas turbine is disturbed by wakes and shock waves from the nozzle guide vanes upstream. These disturbances lead to increased heat transfer to the blade surfaces, the accurate prediction of which is an essential stage in the design process.

The Oxford Rotor experiment consists of a highly instrumented 0.5 m diameter shroudless turbine which is supplied with air from a piston tube during the 200 ms run time and simulates realistic engine Mach and Reynolds numbers. Previous experiments have measured blade surface pressures and heat transfer rates, and compared them with similar data from linear cascades.

The present work is designed to enable the accuracy of rotation terms in computational fluid dynamics (CFD) calculations to be assessed, by providing heat transfer data from the rotating frame in the absence of wakes. Flow disturbances were avoided by removing the nozzle guide vanes, the correct angle of incidence onto the rotor blades being achieved by rotating the rotor in the reverse direction. Blade surface heat fluxes were measured using thin film gauges. In the absence of the usual blade-passing fluctuations, the root-mean-square fluctuation in heat flux was typically only 7% of the DC level.

Nusselt numbers are compared with cascade data and CFD predictions from both a three-dimensional viscous Navier-Stokes equation solver and a two-dimensional boundary layer prediction. The low inlet turbulence level produced a long laminar region on the suction surface followed by sudden transition. CFD predictions of Nusselt number on this surface were very sensitive to the choice of boundary layer state, and the experimental level was approximately mid-way between predictions with a transitional intermittency distribution and those with a turbulent distribution. On the pressure surface the levels were approximately 25% below predicted levels, and possible reasons for this are considered.
A Simulation of the Unsteady Interaction of a Centrifugal Impeller With its Vaned Diffuser: Flows Analysis
Authors: Dawes W. N.
Published: February 2015

The aim of this paper is to help advance our understanding of the complex, three-dimensional, unsteady flow associated with the interaction of a splattered centrifugal impeller and its vaned diffuser. A time-resolved simulation is presented of the Krain stage performed using a time-accurate, 3D, unstructured mesh, solution-adaptive Navier-Stokes solver.

The predicted flowfield, compared with experiment where available, displays a complex, unsteady interaction especially in the neighbourhood of the diffuser entry zone which experiences large periodic flow unsteadiness. Downstream of the throat, although the magnitude of this unsteadiness diminishes rapidly, the flow has a highly distorted three-dimensional character.

The loss levels in the diffuser are then investigated to try and determine how time-mean loss levels compare with the levels expected from “equivalent” steady flow analysis performed by using the circumferentially averaged exit flow from the impeller as inlet to the diffuser. It is concluded that little loss could be attributed directly to unsteady effects but rather that the principle cause of the rather high loss levels observed in the diffuser is the strong spanwise distortion in swirl angle at inlet which initiates a strong hub/comer stall.
A Finite Element Approach to the Analysis of Rotating Bladed-Disk Assemblies Coupled With Flexible Shaft
Authors: Zhang Wen , Wang Wenliang , Wang Hao , Tang Jiong
Published: February 2015

A method for dynamic analysis of flexible bladed-disk/shaft coupled systems is presented in this paper. Being independant substructures first, the rigid-disk/shaft and each of the bladed-disk assemblies are analyzed separately in a centrifugal force field by means of the finite element method. Then through a modal synthesis approach the equation of motion for the integral system is derived. In the vibration analysis of the rotating bladed-disk substructure, the geometrically nonlinear deformation is taken into account and the rotationally periodic symmetry is utilized to condense the degrees of freedom into one sector. The final equation of motion for the coupled system involves the degrees of freedom of the shaft and those of only one sector of each of the bladed-disks, thereby reducing the computer storage. Some computational and experimental results are given.