bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and Numerical Examinations of a Transonic Compressor-Stage With Casing Treatment
Authors: Schönweitz D. , Voges M. , Goinis G. , Enders G. , Johann E. 
Published: November 2013

The flow in the blade tip vicinity of the transonic first stage of a multi-stage axial flow compressor with variable inlet guide vane (IGV) and casing treatment (CT) above the rotor is investigated experimentally and numerically with focus on the effects of the CT on flow structures and compressor performance.
For the experimental part of this study, conventional performance instrumentation is used to estimate the operating condition of the compressor. Radial distributions of total temperature and total pressure are taken at the leading edges of the stators for comparison with simulations as well as for adjusting the operating conditions of the compressor. The velocity field in the rear part of the first-rotor is determined with Particle Image Velocimetry (PIV) at 90% and 96% radial height using two periscope light sheet probes. The employed PIV setup allows a spatial resolution of 0.7 mm × 0.7mm and thus a similar resolution as the spatial discretization in the simulation. For the numerical part of the study, time-accurate simulations are conducted for the same operating conditions as during experiments. Additional simulations of the same configuration with smooth casing are conducted in order to estimate the effect of the CT on the flow.
The examination of PIV measurements and corresponding simulations exposes complex vortical structures originating from the interaction of the rotor bow shock with the IGV trailing edge, CT, IGV wake and the tip leakage vortex. The associated induced velocities together with the general passage flow form a complex flow field with significantly altered blockage compared to a common flow field in the tip vicinity. Position and trajectory of the tip leakage vortex are deduced from interactions between tip leakage vortex and IGV wake / CT.
The detailed comparison of the tip region of simulations with and without CT shows that the CT influences pressure rise and flow parameters in a wide radial range due to a radial redistribution of the flow. Correspondingly, a rotor with CT can achieve an increased total pressure rise compared to a rotor with smooth casing, with only minor effects on the efficiency.
Performance Evaluation of Non-Uniformly Fouled Axial Compressor Stages by Means of Computational Fluid Dynamic Analyses
Authors: Aldi Nicola , Morini Mirko , Pinelli Michele , Spina Pier Ruggero , Suman Alessio , Venturini Mauro 
Published: November 2013

In this paper, three-dimensional numerical simulations are carried out to evaluate the effect of fouling on an axial compressor stage. A numerical model of the NASA Stage 37, validated in previous papers of the same authors against experimental data available from literature, is used as a case study.
The occurrence of fouling is simulated by imposing different spanwise distributions of surface roughness, in order to analyze its effect on compressor performance. To this aim, both the stage performance maps of the fouled compressor and the spanwise distribution of work and losses are analyzed and discussed. Moreover, the definition of an averaged roughness parameter is suggested, to characterize the different roughness distributions.
The results show that the drop of overall performance can actually be predicted by means of the numerical model. Moreover, detailed information about fluid-dynamic phenomena can be analyzed on the basis of the actual distribution of surface roughness on rotor blades.
Experimental and CFD Studies of NGV Endwall Cooling
Authors: Thomas Mitra , Kirollos Benjamin , Jackson Dougal , Povey Thomas 
Published: November 2013

For engines operating at high turbine entry temperatures it is increasingly important to cool the high pressure nozzle guide vane (HP NGV) endwalls. This is particularly so for low NOx combustors operating with flatter outlet temperature distributions.
Double-row arrangements of film/ballistic cooling holes upstream of the NGV passage have been employed in production engines. Optimisation of such systems is non-trivial, however, due to the complex nature of the flow in the endwall region. Previous studies have reported that strong cross passage pressure gradients lead to migration of coolant flow and boundary layer flow within the passage. In addition the vane potential field effects lead to non-uniform blowing ratios for holes upstream of the vanes. It has also been reported that inlet total pressure and turbulence profiles have a significant effect on the development of the film cooling layer.
In this study, endwall film cooling flows are studied experimentally in a large-scale low-speed cascade tunnel with engine-realistic combustor geometry and turbulence profiles. At very low blowing ratios mild cross-passage migration effects are observed. At higher blowing ratios more realistic of the engine situation no cross-passage migration is observed. This finding is somewhat contrary to the classical view of endwall secondary flow, which is presented as significant at the scale of the vane passage by several authors. The difference arises in part because of the thinning of the boundary layer due to strong acceleration in the vane inlet contraction. The findings are further supported by CFD simulations.
Methods of improving conventional double-row systems to offer improved cooling of the endwall are also discussed.
Experimental Analysis of Abradable Labyrinth Seal Leakage With Simulated Groove: Part 2
Authors: Innocenti Luca , Ricupero Stefania , Pandit Rajeev Kumar , Sheng Nuo 
Published: November 2013

In the secondary flow path of centrifugal compressors, abradable seals are in high demand when higher efficiency is the main requirement. This is because abradable seals can maintain very tight clearances between static and rotating components compared to other sealing technology. However, due to the rubbing of the teeth into the abradable material, some grooves can form. The flow physics and mass leakage of abradable seals are strongly dependent on the presence of these grooves and their shape. For cases where no grooves are present, seal leakage is mainly a function of inlet pressure, pressure ratio across the seal and tooth radial clearance. Once grooves are formed, the flow physics and seal leakage also are a function of groove dimensions, tooth clearance and tooth axial position inside the groove.
The scope of the present paper is to describe the experimental campaign that has been performed to validate the numerical analysis of part 1 of the paper [1]. The experimental test matrix investigates the groove and teeth positioning effects on seal leakages. To achieve higher accuracy, the key geometric parameters, such as radial and axial gaps, were controlled in the test sample during the tests. For cases where grooves are present the experimental measurements reveal that flow field strongly depends on groove dimensions, tooth radial clearance and tooth axial position. The authors, finally, found generally a good agreement between numerical predictions and measured data, both in terms of leakage and pressure drops across the teeth.
A Review of the Oxford Turbine Research Facility
Authors: Chana Kam , Cardwell Dave , Jones Terry 
Published: November 2013

Gas turbine engine efficiency and reliability is generally improved through better understanding and improvements to the design of individual components. The life limiting component of the modern gas turbine is the high pressure (HP) turbine stage due to the arduous environment. Over the last 50 years significant research effort has been focused on advancing blade cooling designs and materials.
Due to practical limitations little fundamental research on the turbine system is performed in the operating gas turbine engine. Consequently different types of experimental approaches have been developed over the last 4 decades to study the flow and in particular the heat transfer and cooling in turbines.
In general the facilities can be divided into continuous running or short duration and cascade or rotating. Over the last 30 years short duration facilities have dominated the research in the study of turbine heat transfer and cooling.
The Oxford Turbine Research Facility (formerly known as the QinetiQ Turbine Test Facility, The Isentropic Light Piston Facility and The Isentropic Light Piston Cascade) is a short duration facility developed and built in the late 1970s and early 1980s for turbine heat transfer and cooling studies.
This paper presents the developments and measurements taken on the facility over the last 35 years, including the type of research that has been conducted and, the current capability of the facility.
Considerations on the Compression System Preliminary Design of a Short Haul Aircraft Propulsion System
Authors: Piscopo Giovanni , Zachos Pavlos K. , Pilidis Pericles 
Published: November 2013

The preliminary design of turbomachinery components is strongly affected by the application process. This paper documents a compressor comparative design assessment which was conducted with the intent of to highlight the rationale of proposing a new propulsion system for use on short haul aircraft, similar to the Embraer E-Jet. This study establishes and discusses the compressor figures of merit pertaining to short haul operation and their influence on the desired compression layout.
A computational tool to undertake compressor designs is developed and validated against the NASA E3 published compressor layout. With the aid of this software, a few alternative compressor layouts that meet the established criteria are suggested.
The best candidates are highlighted and further studied in terms of individual design parameters such as temperature rise distribution, number of stages and off-design performance. The figures of merit that dictate particular design choices are highlighted and commented. The most advanced candidate design is found to yield a very respectable performance compared to current production engines of the same class. This work aims at highlighting the process through which a modern compression system is designed at a preliminary stage and the design challenges confronting it.
Dosage Compensation via Transposable Element Mediated Rewiring of a Regulatory Network
Authors: Ellison Christopher E. , Bachtrog Doris 
Published: November 2013

Getting the Dosage RightAs sex chromosomes evolve, they must compensate for differential gene dosage, especially in non-sex-specific genes. However, owing to the relative rarity of chromosomes that are in the process of becoming sex chromosomes, the ongoing evolutionary processes resulting in dosage compensation are unclear.Ellison and Bachtrog(p.846; see the Perspective byChuong and Feschotte) identified a specific transposable element involved in dosage compensation in males on the evolutionarily new neo-X chromosome ofDrosophila miranda. A particular copy of this transposable element has been inserted at chromatin entry sites on the neo-X chromosome that favorably binds to the male-specific lethal complex, which in turn facilitates the spreading of chromatin silencing on a single chromosome to provide dosage compensation.
Detection of Rickettsia in Rhipicephalus sanguineus Ticks and Ctenocephalides felis Fleas from Southeastern Tunisia by Reverse Line Blot Assay
Authors: Khrouf Fatma , M'Ghirbi Youmna , Znazen Abir , Ben Jemaa Mounir , Hammami Adnene , Bouattour Ali 
Published: November 2013

ABSTRACT

Ticks (
n
= 663) and fleas (
n
= 470) collected from domestic animals from southeastern Tunisia were screened for
Rickettsia
infection using reverse line blot assay. Evidence of spotted fever group
Rickettsia
was obtained. We detected
Rickettsia felis
in fleas,
Rickettsia massiliae
Bar 29 and the
Rickettsia conorii
Israeli spotted fever strain in ticks, and
Rickettsia conorii
subsp.
conorii
and
Rickettsia
spp. in both arthropods. The sensitivity of the adopted technique allowed the identification of a new association between fleas and
R. conorii
subsp.
conorii
species. The presence of these vector-borne
Rickettsia
infections should be considered when diagnosing this disease in humans in Tunisia.
Seven Hours to Adequate Antimicrobial Therapy in Urosepsis Using Isothermal Microcalorimetry
Authors: Braissant Olivier , Müller Georg , Egli Adrian , Widmer Andreas , Frei Reno , Halla Armin , Wirz Dieter , Gasser Thomas C. , Bachmann Alexander , Wagenlehner Florian , Bonkat Gernot 
Published: November 2013

ABSTRACT
Urosepsis can progress toward severe sepsis, septic shock, and, ultimately, death. Rapid antimicrobial susceptibility testing is crucial to decrease mortality and morbidity. This report shows that isothermal microcalorimetry can provide an antibiogram within 7 h with a sensitivity of 95% and specificity of 91% using Vitek-2 system as a reference.
Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Staphylococcus spp. and Enterococcus spp
Authors: Bobenchik April M. , Hindler Janet A. , Giltner Carmen L. , Saeki Sandra , Humphries Romney M. 
Published: November 2013

ABSTRACT

Vitek 2 (bioMérieux, Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility testing system. We compared MIC results obtained by Vitek 2 to those obtained by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method for 134 staphylococcal and 84 enterococcal clinical isolates. Nineteen agents were evaluated, including all those available on Vitek 2 for testing staphylococci and enterococci. The resistance phenotypes tested included methicillin-resistant
Staphylococcus aureus
(MRSA) (
n
= 58),
S. aureus
with inducible clindamycin resistance (ICR) (
n
= 30), trimethoprim-sulfamethoxazole-resistant MRSA (
n
= 10), vancomycin-resistant
Enterococcus
(
n
= 37), high-level gentamicin-resistant
Enterococcus
(
n
= 15), linezolid-resistant
Enterococcus
(
n
= 5), and daptomycin-nonsusceptible
Enterococcus faecalis
(
n
= 6). For the staphylococci, there was 98.9% categorical agreement (CA). There was one very major error (VME) for gentamicin in a
Staphylococcus hominis
isolate, six VMEs for inducible clindamycin in
S. aureus
isolates, and two major errors (ME) for daptomycin in an
S. aureus
and a
Staphylococcus epidermidis
isolate. For enterococci, there was 97.3% CA. Two VMEs were observed for daptomycin in isolates of
E. faecalis
and 2 ME, 1 for high-level gentamicin resistance and 1 for nitrofurantoin, in
E. faecium
isolates. Overall, there was 98.3% CA and 99% essential agreement for the testing of staphylococci and enterococci by the Vitek 2. With the exception of detecting ICR in
S. aureus
, Vitek 2 performed reliably for antimicrobial susceptibility testing of staphylococci and enterococci.
Comparison of Simplexa Universal Direct PCR with Cytotoxicity Assay for Diagnosis of Clostridium difficile Infection: Performance, Cost, and Correlation with Disease
Authors: Landry Marie L. , Ferguson David , Topal Jeffrey 
Published: November 2013

ABSTRACT

Simplexa
Clostridium difficile
universal direct PCR, a real-time PCR assay for the detection of the
C. difficile
toxin B (
tcdB
) gene using the 3M integrated cycler, was compared with a two-step algorithm which includes the C. Diff Chek-60 glutamate dehydrogenase (GDH) antigen assay followed by cytotoxin neutralization. Three hundred forty-two liquid or semisolid stools submitted for diagnostic
C. difficile
testing, 171 GDH antigen positive and 171 GDH antigen negative, were selected for the study. All samples were tested by the C. Diff Chek-60 GDH antigen assay, cytotoxin neutralization, and Simplexa direct PCR. Of 171 GDH-positive samples, 4 were excluded (from patients on therapy or from whom duplicate samples were obtained) and 88 were determined to be true positives for toxigenic
C. difficile
. Of the 88, 67 (76.1%) were positive by the two-step method and 86 (97.7%) were positive by PCR. Seventy-nine were positive by the GDH antigen assay only. Of 171 GDH antigen-negative samples, none were positive by PCR. One antigen-negative sample positive by the cytotoxin assay only was deemed a false positive based on chart review. Simplexa
C. difficile
universal direct PCR was significantly more sensitive for detecting toxigenic
C. difficile
bacteria than cytotoxin neutralization (
P
= 0.0002). However, most PCR-positive/cytotoxin-negative patients did not have clear
C. difficile
disease. The estimated cost avoidance provided by a more rapid molecular diagnosis was outweighed by the cost of isolating and treating PCR-positive/cytotoxin-negative patients. The costs, clinical consequences, and impact on nosocomial transmission of treating and/or isolating patients positive for toxigenic
C. difficile
by PCR but negative for
in vivo
toxin production merit further study.
Novel H7N9 Influenza Virus Shows Low Infectious Dose, High Growth Rate, and Efficient Contact Transmission in the Guinea Pig Model
Authors: Gabbard Jon D. , Dlugolenski Daniel , Van Riel Debby , Marshall Nicolle , Galloway Summer E. , Howerth Elizabeth W. , Campbell Patricia J. , Jones Cheryl , Johnson Scott , Byrd-Leotis Lauren , Steinhauer David A. , Kuiken Thijs , Tompkins S. Mark , Tripp Ralph , Lowen Anice C. , Steel John 
Published: November 2013

ABSTRACT
The zoonotic outbreak of H7N9 subtype avian influenza virus that occurred in eastern China in the spring of 2013 resulted in 135 confirmed human cases, 44 of which were lethal. Sequencing of the viral genome revealed a number of molecular signatures associated with virulence or transmission in mammals. We report here that, in the guinea pig model, a human isolate of novel H7N9 influenza virus, A/Anhui/1/2013 (An/13), is highly dissimilar to an H7N1 avian isolate and instead behaves similarly to a human seasonal strain in several respects. An/13 was found to have a low 50% infectious dose, grow to high titers in the upper respiratory tract, and transmit efficiently among cocaged guinea pigs. The pH of fusion of the hemagglutinin (HA) and the binding of virus to fixed guinea pig tissues were also examined. The An/13 HA displayed a relatively elevated pH of fusion characteristic of many avian strains, and An/13 resembled avian viruses in terms of attachment to tissues. One important difference was seen between An/13 and both the H3N2 human and the H7N1 avian viruses: when inoculated intranasally at a high dose, only the An/13 virus led to productive infection of the lower respiratory tract of guinea pigs. In sum, An/13 was found to retain fusion and attachment properties of an avian influenza virus but displayed robust growth and contact transmission in the guinea pig model atypical of avian strains and indicative of mammalian adaptation.
Are familial factors underlying the association between socioeconomic position and prescription medicine? A register-based study on Danish twins
Authors: Madsen Mia , Andersen Per Kragh , Gerster Mette , Andersen Anne-Marie Nybo , Osler Merete , Christensen Kaare 
Published: November 2013

ObjectivesAlthough well established, the association between socioeconomic position and health and health behaviour is not clearly understood, and it has been speculated that familial factors, for example, dispositional factors or exposures in the rearing environment, may be underlying the association. The objective was to compare prescription fillings within twin pairs who are partly or fully genetically identical and share childhood exposures.DesignTwin cohort study.SettingDenmark.ParticipantsData from the Danish Twin Registry were linked to registers in Statistics Denmark and the Danish Registry of Medicinal Product statistics. A total of 8582 monozygotic (MZ) and 15 788 dizygotic same sex (DZSS) twins were included.Outcome measuresNumber of prescription fillings during follow-up (1995–2005) was analysed according to education and income. Results of unpaired and intrapair analyses were compared.ResultsAn inverse social gradient in filling of prescriptions for all-purpose and system-specific drugs was observed in the unpaired analyses. In the intrapair analyses, associations were attenuated some in DZSS and more in MZ twins. Filling of drugs targeting the nervous system was still strongly associated with income in the intrapair analyses.ConclusionsFamilial factors seem to account for part of the observed social inequality in filling of prescription medicine.
Active buildings: modelling physical activity and movement in office buildings. An observational study protocol
Authors: Smith Lee , Ucci Marcella , Marmot Alexi , Spinney Richard , Laskowski Marek , Sawyer Alexia , Konstantatou Marina , Hamer Mark , Ambler Gareth , Wardle Jane , Fisher Abigail 
Published: November 2013

IntroductionHealth benefits of regular participation in physical activity are well documented but population levels are low. Office layout, and in particular the number and location of office building destinations (eg, print and meeting rooms), may influence both walking time and characteristics of sitting time. No research to date has focused on the role that the layout of the indoor office environment plays in facilitating or inhibiting step counts and characteristics of sitting time. The primary aim of this study was to investigate associations between office layout and physical activity, as well as sitting time using objective measures.Methods and analysisActive buildings is a unique collaboration between public health, built environment and computer science researchers. The study involves objective monitoring complemented by a larger questionnaire arm. UK office buildings will be selected based on a variety of features, including office floor area and number of occupants. Questionnaires will include items on standard demographics, well-being, physical activity behaviour and putative socioecological correlates of workplace physical activity. Based on survey responses, approximately 30 participants will be recruited from each building into the objective monitoring arm. Participants will wear accelerometers (to monitor physical activity and sitting inside and outside the office) and a novel tracking device will be placed in the office (to record participant location) for five consecutive days. Data will be analysed using regression analyses, as well as novel agent-based modelling techniques.Ethics and disseminationThe results of this study will be disseminated through peer-reviewed publications and scientific presentations. Ethical approval was obtained through the University College London Research Ethics Committee (Reference number 4400/001).