bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Development of the Profile Boundary Layer in a Turbine Environment
Authors: Hourmouziadis J. , Buckl F. , Bergmann P. 
Published: April 2015

Cascade testing tries to simulate the actual flow conditions encountered in a turbine. However, it is neither possible to reproduce the free stream turbulence structure of the turbomachinery, nor the periodic wake effects of upstream blade rows. The usual understanding is that the latter in particular results in a significantly different behaviour of the boundary layer in the engine.
Experimental results from cascades and turbine rigs are presented. Grid generated free stream turbulence structure is compared to that in the turbine. Measurements of the profile pressure distribution, flush mounted hot films and flow visualization were used for the interpretation of the test results. Some observations of the boundary layer development in the cascade, on the guide vanes and on rotor blades with typically skewed boundary layers are shown indicating essentially similar behaviour in all cases.
Fatigue Crack Growth Resistance of Advanced Blade Materials
Authors: Wilson D. A. , Deluca D. P. , Cowles B. A. , Stucke M. A. 
Published: April 2015

The best measure of performance in a jet engine is the thrust-to-weight ratio. Cast single-crystal superalloys provide higher temperature capability and offer opportunities for significant improvements in future jet engine performance and durability. The highly anistropic behavior of these advanced materials, which includes modulus, strength, and ductility variation with crystallographic orientation, pose potentially significant problems for design and life prediction of advanced turbine blades.
The objective of this paper is to provide a better understanding of the crack growth behavior in this advanced turbine blade material by evaluating the effect of temperature, frequency, orientation, and thickness.
Experimental Investigation of Boundary Layer Separation With Heated Thin-Film Sensors
Authors: Pucher P. , Göhl R. 
Published: April 2015

The heated thin-film method was adapted to meet the requirements of investigations on boundary layer behaviour in a turbine rig. Special multi-sensor probes of vaporized nickel on a polyimide foil were developed and applied to the vanes.
Basic experiments with an airfoil in a free stream were carried out and a reliable interpretation of the thin-film results was found by comparison with pressure distribution, flow visualization and laser measurements. It can be shown that this measuring device is a suitable method for the investigation of separation bubbles and boundary layer transition.
Analytical Tools for the Analyses of Coal and its Combustion Products
Authors: Raj S. , Raj R. 
Published: April 2015

Coal, due to its heterogenous nature and complex structure; physical, chemical and petrographic, introduces two-fold complications during its combustion in power generation. Organic and inorganic constituents in various petrographic states alter chemically and physically. The products of coal combustion; unburned carbon, deposits, oxides of metals and non-metals, metal and non-metal complexes, need to be identified qualitatively and quantitatively to increase the coal combustion efficiency and to optimize the durability of power plant components.
This paper will describe the usage of various analytical tools like NMR, ESR, IR, Electron Microscopy, X-Ray, Fluorescent Microscopy coupled with Wet Analysis to analyze coal and its derivatives. Each spectroscopy will be related to a specific aspect of coal and its derivatives. The limiting conditions and the range of application of each of the tools will be provided. The knowledge of these ranges will help in monitoring accurate emission levels of a particulate concentration, NOx, SOx and will control several phenomena such as deposition, corrosion and erosion.
NDT of Injection Molded Green and Sintered SiC Turbine Parts
Authors: Grellner W. , Schwetz K. A. , Lipp A. 
Published: April 2015

Nondestructive evaluation of ceramic turbine components has to give special consideration to geometrical as well as to material requirements of these parts. Test procedures have to be able to detect all essential defects. As present X-ray penetration, especially the microfocus technique, is the most promising examination routine for special ceramics of complex shape.
Actual developments discussed, include the use of image intersifiers for real time monitoring and utilization of digital image processing to increase defect detectability, to decrease costs and to fabricate ceramic turbine parts of higher reliability.
An Approach to an Integrated Control System for a Modern Fighter Aircraft Engine
Authors: Lemmin Jürgen 
Published: April 2015

In the field of today’s military aircraft engines, the engine control system consists in most cases of hydromechanical controls, as such, with an electronic supervisory system. This type of control makes the integration of engine and aircraft systems rather difficult. Even with the Tornado engine which features a full authority electronic engine controller, only initial steps in systems integration are realized.
With the introduction of digital electronics into both the engine control and the aircraft systems, together with the availability of data highway systems, large scale systems integration can be envisaged on future fighter aircraft, with the resultant improvement in overall weapon system performance.
This paper puts forward a proposal for a control concept for a reheated fighter engine, and outlines possibilities for integration with aircraft systems.
Operating Efficiencies of a Lysholm, Helical Expander for Brayton-Cycle Heat Engines
Authors: Myers Blake , Deis Gary , Shell Tom 
Published: April 2015

Operating tests on a Lysholm helical expander have been done to develop a data base for comparing the performance of helical expanders with turbine expanders by using simple scaling arguments. The eventual goal of such work would be to develop a rugged and reliable ceramic helical expander for operating at temperatures up to 1300°C (2400°F). We used a 127.5 mm (5.020 in.) metal expander on which we measured seven performance variables against applied pressure ratio at six shaft speeds and an inlet gas temperature of 100°C (212°F).
Our data system included: a torque and angular-speed cell to measure power; flow, pressure, and temperature instrumentation; and a data reduction program. Test results are presented in seven data plots; equations for computing the performance variables are tabulated.
Adiabatic efficiency was found to be at least 85% in the pressure ratio range of 2.75 to 5.00. Performance is strongly influenced by gas leakage. Large machines with clearance ratios the same as smaller machines would benefit by size scaling effects. We expect that ceramic helical expanders for 1300°C service would be able to operate at adiabatic efficiencies higher than 85%.
Effect of Area Ratio on the Performance of a 5.5:1 Pressure Ratio Centrifugal Impeller
Authors: Schumann Lawrence F. , Clark David A. , Wood Jerry R. 
Published: April 2015

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was changed by successively cutting back the impeller exit axial width from an initial value of 7.57 mm to a final value of 5.97 mm. In all, four separate area ratios were tested. For each area ratio a series of impeller exit axial clearances was also tested. Test results are based on impeller exit surveys of total pressure, total temperature, and flow angle at a radius 1.115 times the impeller exit radius.
Results of the tests at design speed, peak efficiency, and an exit tip clearance of 8 percent of exit blade height show that the impeller equivalent pressure recovery coefficient peaked at a design point area ratio of approximately 2.748 while the impeller aerodynamic efficiency peaked at a lower value of area ratio of approximately 2.55. The variation of impeller efficiency with clearance showed expected trends with a loss of approximately 0.4 points in impeller efficiency for each percent increase in exit axial tip clearance for all impellers tested. The data also indicated that the impeller would probably separate at design area ratios greater than 2.748. An analysis was performed with a quasi-three-dimensional inviscid computer code which confirmed that a minimum velocity ratio was attained near this area ratio thus indicating separation. This data can be used to verify impeller flow models which attempt to account for very high diffusion and possible separation.
Numerical Investigation of Unsteady Subsonic Compressible Flows Through an Oscillating Cascade
Authors: Fransson T. H. , Pandolfi M. 
Published: April 2015

A method for solving numerically the fully time-dependent two-dimensional Euler equations, applied to unsteady subsonic flow through vibrating turbomachine cascades with thin blades, is developed. The blades are assumed to vibrate at a constant interblade phase angle and the computed region is reduced to one blade passage, with the implementation of the interblade phase angle as a periodicity condition. The reliability of the method is validated by comparing it with an analytical flat plate theory, and the importance of radiative inlet and outlet boundary conditions for unsteady flow calculations is shown in an example.
The method can be used to compute the aerodynamic force and damping coefficients acting on the blades and to investigate the propagation of unsteady disturbances through a cascade in flutter conditions.
Durability and Damage Tolerance Assessment of the TF34-100 Engine
Authors: Ogg Jon S. , Reinhold Ronald R. 
Published: April 2015

The critical nature of the TF34-100 engine to the Air Force’s A-10 Close Air Support weapon system made it important to obtain the best possible visibility of the engine’s future structural maintenance needs and component life limits. Accordingly, an in-depth structural durability and damage tolerance assessment was performed on this engine by a joint Air Force/General Electric team.
Results of the assessment team’s unprecedented analysis efforts culminated in a comprehensive Structural Maintenance Plan that identified both current and future maintenance actions necessary for insuring maximum flight safety. The plan entailed component inspection and replacement intervals, inspection systems, preferred modifications/reworks, and a life growth plan for extending the useful life of the TF34-100 upwards to 8000 A-10 mission hours.
This paper details the nature and extent of effort undertaken in conducting the 18 month structural assessment.
Transportable Gas Turbine Cogeneration Plant for German Coal Mine
Authors: Kowollik Gottfried , Ruhrkohle-Bergbau  , Heimer Heiko 
Published: April 2015

This paper describes a pilot project at a German coal mine to utilize a transportable gas turbine cogeneration plant to produce electrical power and warm water.
Medium Btu gas with varying CH4 content is scavenged from several mines and will be used as a low cost waste fuel for the gas turbine. The mine currently requires substantial venting to control methane content in the shaft air.
Assessment of a Three-Dimensional Potential Code for Axial and Radial Blade Row Flows
Authors: Frühauf H.-H. , Krämer D. , Küster U. 
Published: April 2015

An assessment of a three-dimensional potential code is presented for axial and radial blade row flows, for which experimental data or computational results are available. The prediction of a flow case with severe cross flow is included. Numerous 3-D potential flow effects will be discussed.
The conservative full potential equation for 3-D transonic flow is solved by a robust SLOR method. A new formulation of the downstream flow ensures the computability of blade row flows with arbitrary spanwise circulation distributions. Blade circulation distribution and downstream flow properties are obtained as a part of the solution. The surface representation in parameter form in the geometry definition program and the mesh generation program, as well as the tensor notation of the basic equation and a configuration-independent vortex sheet approximation prediction, ensure the computability of flows through blade rows with arbitrary complex geometries. The CRAY-1/M incore version of the code is inexpensive enough to be used in the aerodynamic design process of new blade rows with irrotational inflows.
The Application of Active Magnetic Bearings to a Natural Gas Pipeline Compressor
Authors: Foster E. G. , Kulle V. , Peterson R. A. 
Published: April 2015

The installation and operation of an active magnetic bearing in conjunction with a modified mechanical dry gas seal on a natural gas pipeline compressor is presented.
The emphasis of this paper is centered on the active magnetic bearing.
The active magnetic bearing was developed by Société de Mécanique Magnétique (S2M) of Vernon France. The first successful application to a natural gas pipeline compressor was a co-operative effort between NOVA, AN ALBERTA CORPORATION, S2M, and Magnetic Bearing Incorporated (MBI) of Radford, Virginia.
This paper represents a technical and economic assessment of the bearing, including installation and operational data.
Power Increase of Gas Turbines by Inlet Air Pre-Cooling With Absorption Refrigeration Utilizing Exhaust Waste Heat
Authors: Malewski Werner F. , Holldorff Günther M. 
Published: April 2015

Using heat energy from the tail-end of gas turbine exhaust, an ammonia absorption refrigeration system can precool the inlet air to a temperature slightly above the freezing point of the air humidity.
The concept is described and shows how it indicates a significant increase of gas turbine power output, depending on ambient conditions.
The Development of a Multi-Stage Heavy-Duty Transonic Compressor for Industrial Gas Turbines
Authors: Farkas F. 
Published: April 2015

The decision was made to use a heavy-duty, 12-stage transonic compressor for the new Type 8 Brown Boveri gas turbine.
With this advanced concept, it became possible both to increase the pressure ratio to 16:1 and to reduce the number of stages by half. The wide-chord, low aspect-ratio blade design brought about a further decrease in the total number of components and a reduction of the mechanical stresses. A variable inlet guide vane was added to provide flexibility in combined cycle operation.
Appropriate computer-assisted design systems were developed for evaluation of design and off-design aerodynamics.
As a back-up for the design work, tests were run on several model compressors to explore and study aerodynamic and mechanical behavior. Detailed field measurements were also taken on the prototype units of the Type 8 as a final check to confirm the expected values.
Taoist Tai Chi® and Memory Intervention for Individuals with Mild Cognitive Impairment
Authors: Fogarty Jennifer N. , Murphy Kelly J. , McFarlane Bruce , Montero-Odasso Manuel , Wells Jennie , Troyer Angela K. , Trinh Daniel , Gutmanis Iris , Hansen Kevin T. 
Published: April 2015

Objective:It was hypothesized that a combined Taoist Tai Chi (TTC) and a memory intervention program (MIP) would be superior to a MIP alone in improving everyday memory behaviors in individuals with amnestic mild cognitive impairment (aMCI). A secondary hypothesis was that TTC would improve cognition, self-reported health status, gait, and balance.Method:A total of 48 individuals were randomly assigned to take part in MIP + TTC or MIP alone. The TTC intervention consisted of twenty 90 min sessions. Outcome measures were given at baseline, and after 10 and 22 weeks.Results:Both groups significantly increased their memory strategy knowledge and use, ratings of physical health, processing speed, everyday memory, and visual attention. No preferential benefit was found for individuals in the MIP + TTC group on cognition, gait, or balance measures.Conclusions:Contrary to expectations, TTC exercise did not specifically improve cognition or physical mobility. Explanations for null findings are explored.
Protective Efficacy of the Conserved NP, PB1, and M1 Proteins as Immunogens in DNA- and Vaccinia Virus-Based Universal Influenza A Virus Vaccines in Mice
Authors: Wang Wenling , Li Renqing , Deng Yao , Lu Ning , Chen Hong , Meng Xin , Wang Wen , Wang Xiuping , Yan Kexia , Qi Xiangrong , Zhang Xiangmin , Xin Wei , Lu Zhenhua , Li Xueren , Bian Tao , Gao Yingying , Tan Wenjie , Ruan Li 
Published: April 2015

ABSTRACT

The conventional hemagglutinin (HA)- and neuraminidase (NA)-based influenza vaccines need to be updated most years and are ineffective if the glycoprotein HA of the vaccine strains is a mismatch with that of the epidemic strain. Universal vaccines targeting conserved viral components might provide cross-protection and thus complement and improve conventional vaccines. In this study, we generated DNA plasmids and recombinant vaccinia viruses expressing the conserved proteins nucleoprotein (NP), polymerase basic 1 (PB1), and matrix 1 (M1) from influenza virus strain A/Beijing/30/95 (H3N2). BALB/c mice were immunized intramuscularly with a single vaccine based on NP, PB1, or M1 alone or a combination vaccine based on all three antigens and were then challenged with lethal doses of the heterologous influenza virus strain A/PR/8/34 (H1N1). Vaccines based on NP, PB1, and M1 provided complete or partial protection against challenge with 1.7 50% lethal dose (LD
50
) of PR8 in mice. Of the three antigens, NP-based vaccines induced protection against 5 LD
50
and 10 LD
50
and thus exhibited the greatest protective effect. Universal influenza vaccines based on the combination of NP, PB1, and M1 induced a strong immune response and thus might be an alternative approach to addressing future influenza virus pandemics.
Continual Reintroduction of Human Pandemic H1N1 Influenza A Viruses into Swine in the United States, 2009 to 2014
Authors: Nelson Martha I. , Stratton Jered , Killian Mary Lea , Janas-Martindale Alicia , Vincent Amy L. 
Published: April 2015

ABSTRACT
The diversity of influenza A viruses in swine (swIAVs) presents an important pandemic threat. Knowledge of the human-swine interface is particularly important for understanding how viruses with pandemic potential evolve in swine hosts. Through phylogenetic analysis of contemporary swIAVs in the United States, we demonstrate that human-to-swine transmission of pandemic H1N1 (pH1N1) viruses has occurred continuously in the years following the 2009 H1N1 pandemic and has been an important contributor to the genetic diversity of U.S. swIAVs. Although pandemic H1 and N1 segments had been largely removed from the U.S. swine population by 2013 via reassortment with other swIAVs, these antigens reemerged following multiple human-to-swine transmission events during the 2013-2014 seasonal epidemic. These findings indicate that the six internal gene segments from pH1N1 viruses are likely to be sustained long term in the U.S. swine population, with periodic reemergence of pandemic hemagglutinin (HA) and neuraminidase (NA) segments in association with seasonal pH1N1 epidemics in humans. Vaccinating U.S. swine workers may reduce infection of both humans and swine and in turn limit the role of humans as sources of influenza virus diversity in pigs.

IMPORTANCE
Swine are important hosts in the evolution of influenza A viruses with pandemic potential. Here, we analyze influenza virus sequence data generated by the U.S. Department of Agriculture's national surveillance system to identify the central role of humans in the reemergence of pandemic H1N1 (pH1N1) influenza viruses in U.S. swine herds in 2014. These findings emphasize the important role of humans as continuous sources of influenza virus diversity in swine and indicate that influenza viruses with pandemic HA and NA segments are likely to continue to reemerge in U.S. swine in association with seasonal pH1N1 epidemics in humans.
Interregional Coevolution Analysis Revealing Functional and Structural Interrelatedness between Different Genomic Regions in
Human Mastadenovirus D
Authors: Gonzalez Gabriel , Koyanagi Kanako O. , Aoki Koki , Watanabe Hidemi 
Published: April 2015

ABSTRACT

Human mastadenovirus D
(HAdV-D) is exceptionally rich in type among the seven human adenovirus species. This feature is attributed to frequent intertypic recombination events that have reshuffled orthologous genomic regions between different HAdV-D types. However, this trend appears to be paradoxical, as it has been demonstrated that the replacement of some of the interacting proteins for a specific function with other orthologues causes malfunction, indicating that intertypic recombination events may be deleterious. In order to understand why the paradoxical trend has been possible in HAdV-D evolution, we conducted an interregional coevolution analysis between different genomic regions of 45 different HAdV-D types and found that ca. 70% of the genome has coevolved, even though these are fragmented into several pieces via short intertypic recombination hot spot regions. Since it is statistically and biologically unlikely that all of the coevolving fragments have synchronously recombined between different genomes, it is probable that these regions have stayed in their original genomes during evolution as a platform for frequent intertypic recombination events in limited regions. It is also unlikely that the same genomic regions have remained almost untouched during frequent recombination events, independently, in all different types, by chance. In addition, the coevolving regions contain the coding regions of physically interacting proteins for important functions. Therefore, the coevolution of these regions should be attributed at least in part to natural selection due to common biological constraints operating on all types, including protein-protein interactions for essential functions. Our results predict additional unknown protein interactions.

IMPORTANCE
Human mastadenovirus D
, an exceptionally type-rich human adenovirus species and causative agent of different diseases in a wide variety of tissues, including that of ocular region and digestive tract, as well as an opportunistic infection in immunocompromised patients, is known to have highly diverged through frequent intertypic recombination events; however, it has also been demonstrated that the replacement of a component protein of a multiprotein system with a homologous protein causes malfunction. The present study solved this apparent paradox by looking at which genomic parts have coevolved using a newly developed method. The results revealed that intertypic recombination events have occurred in limited genomic regions and been avoided in the genomic regions encoding proteins that physically interact for a given function. This approach detects purifying selection against recombination events causing the replacement of partial components of multiprotein systems and therefore predicts physical and functional interactions between different proteins and/or genomic elements.