bluuebunny/crossref_metadata_2025_split huggingface dataset:
Can We Predict the Failure of Electrical Cardioversion of Acute Atrial Fibrillation? The FinCV Study
Authors: GRÖNBERG TONI , HARTIKAINEN JUHA E. K. , NUOTIO ILPO , BIANCARI FAUSTO , VASANKARI TUIJA , NIKKINEN MARKO , YLITALO ANTTI , AIRAKSINEN K. E. JUHANI 
Published: December 2014

BackgroundData on predictors of failure of electrical cardioversion of acute atrial fibrillation are scarce.MethodsWe explored 6,906 electrical cardioversions of acute (<48 hours) atrial fibrillation in 2,868 patients in a retrospective multicenter study.ResultsThe success rate of electrical cardioversion was 94.2%. In 26% of unsuccessful cardioversions, the cardioversion was performed successfully later. Antiarrhythmic drug therapy, short (<12 hours) duration of atrial fibrillation episode, advanced age, permanent pacemaker, history of atrial fibrillation episodes within 30 days before cardioversion, and β‐blockers were independent predictors of unsuccessful electrical cardioversion. In the subgroup of patients with cardioversion of the first atrial fibrillation episode (N = 1,411), the short duration of episode (odds ratio [OR] = 2.28; 95% confidence interval [CI] 1.34–3.90, P = 0.003) and advanced age (OR = 1.03; 95% CI 1.02–1.05, P < 0.001) were the only independent predictors of unsuccessful cardioversion. After successful cardioversion, the rate of early (<30 days) clinical recurrence of atrial fibrillation was 17.3%. The index cardioversion being performed due to the first atrial fibrillation episode was the only predictor of remaining in the sinus rhythm.ConclusionA short (<12 hours) duration of acute atrial fibrillation is a significant predictor of unsuccessful cardioversion, especially during the first attack. First atrial fibrillation episode was the only predictor of remaining in the sinus rhythm.
Agronomic performance and genetic progress of selected historical soybean varieties in the southern USA
Authors: Rogers Justin , Chen Pengyin , Shi Ainong , Zhang Bo , Scaboo Andrew , Smith S. Faye , Zeng Ailan 
Published: December 2014

AbstractThis study was conducted to compare recently developed and historical soybean varieties and evaluate genetic gain in yield and other agronomic traits in the southern USA. A total of 45 southern varieties from public breeding programs, which were released from 1928 to 2008, were used in this study. Three experiments were conducted in 2007 and 2008 at Keiser, Stuttgart, and Marianna in Arkansas (USA). Varieties with maturity groups (MG) late IV to early V had a yield gain of 21.7 kg/ha/yr from the 1950s to the 2000s, mid to late MG V had a yield gain of 16.4 kg/ha/yr from the 1940s to the 2000s, and MG VIs had a yield gain of 12.4 kg/ha/yr from the 1920s to the 2000s. Yield increased linearly for all combined experiments by 16.8 kg/ha/yr. Plant height remained steady over time for most experiments. No significant changes were observed in maturity. Lodging scores decreased, protein concentration decreased, and oil concentration increased linearly over time for all combined experiments. Hutcheson, Narrow, R97‐1634, and Young were recommended as parent lines in future soybean breeding efforts.
A retrospective observational study to assess adverse transfusion reactions of patients with and without prior transfusion history
Authors: Kato H. , Nakayama T. , Uruma M. , Okuyama Y. , Handa M. , Tomiyama Y. , Shimodaira S. , Takamoto S. 
Published: December 2014

Background and ObjectivesThis study compares the frequency of adverse transfusion reactions (ATRs) after first transfusions with the frequency of ATRs for subsequent (non‐first) transfusions.Materials and MethodsFive hospitals agreed to systematically collect and share 2 years of data. This was a retrospective observational analysis of data including the number of transfusion episodes and ATRs for red blood cells (RBCs), fresh frozen plasma (FFP) and platelet concentrates (PCs) given to first‐time transfusion recipients and to those previously transfused.ResultsFirst transfusion ATRs to RBCs, FFP and PCs were 1·08%, 2·84% and 3·34%, respectively. These are higher than ATR incidences to RBCs (0·69%), FFP (1·91%) and PCs (2·75%) on subsequent transfusions. Specifically, first transfusion incidences of febrile non‐haemolytic transfusion reactions (FNHTRs) to RBCs (0·43%) and allergic reactions to FFP (2·51%) were higher than on subsequent transfusions (RBCs: 0·23%, FFP: 1·65%).ConclusionThere are risks of ATRs on the first transfusion as well as transfusions of patients with transfusion history.
Development of a Centrifugal Compressor With a Variable Geometry Split-Ring Pipe Diffuser
Authors: Salvage J. W. 
Published: December 2014

Higher noise levels resulted when a compressor was scaled to larger capacity. The machine’s sound pressure level was relieved by increasing the distance between the impeller blade tip and diffuser leading edge. However, the part-load surge line deteriorated severely as a consequence. A variable geometry pipe diffuser solved this problem, permitting operation at stringent off-design conditions. The addition of a variable diffuser permits compressor selection very near its most efficient full-load operating point, without regard for limitations normally imposed by part-load requirements.
The principal lessons learned during aerodynamic design refinement include (a) how performance and surge depend upon positioning the variable inlet guide vanes and variable diffuser, and (b) how to define simultaneous variation of inlet guide vanes and diffuser for specific operational objectives. Generally, each operating point requires a unique setting of the variable components to achieve maximum efficiency. However, linked movement is shown to yield both a satisfactory surge line and improved performance for most applications when compared to a compressor without the variable geometry pipe diffuser.
Early Historical Development of the Centrifugal Impeller
Authors: Engeda Abraham 
Published: December 2014

The centrifugal impeller has been in existence for over two hundred years but its perfection and rapid development occurred only in the last sixty years. This paper deals with the early development of the centrifugal impeller in the last and early this century.
The centrifugal impeller is found in centrifugal pumps and compressors. Next to the electric motor, centrifugal pumps and compressors are believed to be the most widely used machines of our time. The field of application of these rotary machines has been continually widening, as they are developed for handling a wider range of liquids and gases at higher pressure and greater temperatures, and whole industries become more and more dependent on them.
The first centrifugal impeller with ten wooden double curved blades and dating back to the fifth century was found in 1772 in an abandoned Portuguese copper mine in San Dominigos. Centrifugal fans had been used for mine ventilation as early as in the sixteenth century.
The invention of the centrifugal impeller is a disputed issue whether the credit goes to Leonardo Da Vinci (1452–1519), who suggested the idea of using centrifugal force for lifting liquid, or to Johann Jordan about 1680. Most place the origin of the centrifugal impeller with Denis Papin in 1689. The importance of Papin’s contribution lies in his understanding of the concept of creating a forced vortex within a circular, or spiral casing by means of blades. Following Papin, Kernelien Le Demour in 1732 and Daniel Gabriel Fahrenheit in 1736 described other designs for centrifugal impellers, but there is no evidence of their practical use.
Euler presented in his 1754 memoir an idealized theoretical application of Newton’s law to centrifugal impellers, based on a conceptualization of his tubular turbine run backwards and now universally known as the “Euler equation”. His publication caused a great development of hydraulic turbines in the eighteenth century, but did little to influence the development of centrifugal impellers, which had to gradually develop through tedious cut-and-try methods. The one thing Euler contributed was to initiate a true mathematical inquiry into the employment of centrifugal force as a means of raising fluid. About the same time as Euler, John Smeaton introduced in 1752 the study of turbomachinery by models. He also defined power as equivalent to the rate of lifting of a weight, a concept that is still fundamental in thermo-fluids.
Today both centrifugal pumps and compressors have reached efficiency levels above 90% and are built in sizes from a few Watts to Megawatts. This paper traces the early historical development of the centrifugal impeller. Factors that promoted and hindered the early development are also discussed.
Analysis of the Transonic Flow at the Inlet of a High Pressure Ratio Centrifugal Impeller
Authors: Eisenlohr Gernot , Dalbert Peter , Krain Hartmut , Pröll Hartwig , Richter Franz-Arno , Rohne Karl-Heinz 
Published: December 2014

In an industrial research project of German and Swiss Turbo Compressor manufacturers a high pressure ratio centrifugal impeller was designed and investigated. Performance measurements and extensive laser measurements (L2F) of the flow field upstream, inside and downstream of the rotor have been carried out. In addition to that, 3D calculations have been performed, mainly for the design point. Some earlier results have been presented by Krain et al., 1995.
With four different viscous 3D-solvers, used in companies of the group, calculations for the design speed were carried out to investigate the suitability of these programs in the various design procedures.
Special attention was given to the area from rotor inlet up to the splitter blades. The results for the flow field obtained with the four viscous 3D-Solvers are compared with one another and with the L2F-measurements.
Gas Turbine Development in Sweden After 1945: A Historical Review
Authors: Thoren Kjell T. E. 
Published: December 2014

The gas turbine development history of Sweden is exciting. By international comparison Sweden and its gas turbine manufacturers are small but can nevertheless claim periods with the worlds highest output, or highest efficiency large industrial gas turbine respectively.
Sweden has always created its own military aircraft and fitting, high performance engines are developed in Sweden in license cooperation with large international manufacturers. The Swedish Air Force ranked number four in the world during the 60s.
Pioneering contributions were also made with small gas turbines, such as high speed turbogenerators in hybrid propulsion systems for cars and trucks.
Professionals know that gas turbine development success does not come easy. A lot of setbacks have to be mastered. The size of the crew is not always significant in the process.
Heat Transfer Coefficient Measurements of Film-Cooling Holes With Expanded Exits
Authors: Gritsch M. , Schulz A. , Wittig S. 
Published: December 2014

Detailed measurements of heat transfer coefficients in the nearfield of three different film-cooling holes are presented. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fan-shaped and a laidback fanshaped hole). They were tested over a range of blowing ratios M = 0.25…1.75 at an external crossflow Mach number of 0.6 and a coolant-to-mainflow density ratio of 1.85. Additionally, the effect of the internal coolant supply Mach number is addressed.
Temperatures of the diabatic surface downstream of the injection location are measured by means of an infrared camera system. They are used as boundary conditions for a finite element analysis to determine surface heat fluxes and heat transfer coefficients. The superposition method is applied to evaluate the overall film-cooling performance of the hole geometries investigated.
As compared to the cylindrical hole, both expanded holes show significantly lower heat transfer coefficients downstream of the injection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the injected coolant than the fanshaped hole which leads to lower laterally averaged heat transfer coefficients. Coolant passage crossflow Mach number affects the flowfield of the jet being ejected from the hole and, therefore, has an important impact on film-cooling performance.
Multistage Centrifugal Compressor Surge Analysis: Part II — Numerical Simulation and Dynamic Control Parameters Evaluation
Authors: Arnulfi Gianmario L. , Giannattasio Pietro , Giusto Cristiana , Massardo Aristide F. , Micheli Diego , Pinamonti Piero 
Published: December 2014

This paper describes, from a theoretical point of view, the behaviour of compression systems during surge and the effect of passive and active control devices on the instability limit of the system.
A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1998), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon.
A moveable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analysed; they both address directly the dynamic behaviour of the compression system to displace the surge line to lower flow rates. The influence of system geometry and compressor speed is investigated; the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.
Scaling of Film Cooling Discharge Coefficient Measurements to Engine Conditions
Authors: Rowbury D. A. , Oldfield M. L. G. , Lock G. D. , Dancer S. N. 
Published: December 2014

This paper discusses the need and the procedure for scaling discharge coefficient measurements made in an ambient temperature experiment to render them applicable to the engine situation. Among the dimensionless parameters affecting the discharge coefficients of film cooling holes are the Reynolds number and the coolant Mach number.
Experiments have been conducted in a large scale annular blowdown cascade of film cooled nozzle guide vanes. The coolant system design, using a heavy ‘foreign gas’ (an SF6/Ar mixture) at ambient temperatures, allows the coolant-to-mainstream density ratio and blowing parameters to be matched to engine values.
By using elevated pressure tests, the effect of varying the coolant Reynolds number without external flow is observed experimentally and these results are then used to correct the discharge coefficients measured on the vane with external crossflow. Data is presented and discussed for two cooling hole geometries, namely cylindrical and fanshaped holes.
A Conjugate 3-D Flow and Heat Transfer Analysis of a Thermal Barrier Cooled Turbine Guide Vane
Authors: Bohn Dieter E. , Becker Volker J. 
Published: December 2014

This paper presents the numerical investigations of the flow and heat transfer of two configurations of a transonic turbine guide vane. The basic configuration is a vane with convection cooling. The second configuration is additionally coated with a thermal barrier consisting of ZrO2. The results are obtained with a conjugate heat transfer and flow computer code that has been developed at the Institute of Steam and Gas Turbines. Measurement data is available for the basic configuration and the computational results are compared to the experimental results.
The results show very good agreement between calculated and measured vane surface temperatures. The trailing edge turns out to be subjected to high thermal loads as it is too thin to be cooled effectively. Secondary flow phenomena like the passage vortex and the corner vortex and their impact on the temperature distribution are discussed.
The ZrO2 coating is calculated for a thickness of 300μm. The substrate material temperatures are lowered by about 20 K–29 K in the stagnation point area and by about 27 K–43 K in the shock area on the suction side. At the trailing edge, the coating on the suction side and on the pressure side hardly influences the metal temperature.
Effects of the Rotor Tip Leakage in a Transonic Turbine With Long Blades
Authors: Št’astný Miroslav , Matas Richard , Šafařík Pavel , Jung Alexander R. , Mayer Jürgen F. , Stetter Heinz 
Published: December 2014

A study of the flow in a transonic turbine stage with long and strongly twisted rotor blades is presented. The focus is on the flow in the near tip region of the blade-to-blade passage of the rotor. The flow has been modelled experimentally in a transonic wind tunnel and numerically by means of 2D and 3D Navier-Stokes equation solvers.
The profiles of the rotor cascades are characterized by law turning angles and a high-velocity exit flow. Detailed flow measurements have been carried out and analysed. A comparison has been made between the experimental and numerical results, and is discussed in detail.
The design and test data of the flow through the upper sections of the span are presented. The effects of the tip leakage flow are evaluated and the three-dimensional patterns of the main flow are estimated. Other points of interest are the results of 3D Navier-Stokes analysis of the stage flow as compared to 2D simulations and wind tunnel experiments, together with the question of the limitations of the individual methods as they all use approximations to the actual flow in the turbine stage.
Application of a Three-Dimensional Inverse Method to the Design of a Centrifugal Compressor Impeller
Authors: Demeulenaere Alain , Léonard Olivier , Van den Braembussche René 
Published: December 2014

The use of a three-dimensional Euler inverse method for the design of a centrifugal impeller is demonstrated.
Both the blade shape and the endwalls are iteratively designed. The meridional contour is modified in order to control the mean velocity level in the blade channel, while the blade shape is designed to achieve a prescribed loading distribution between the inlet and the outlet.
The method salves the time dependent Euler equations in a numerical domain of which some boundaries (the blades or the endwalls) move and change shape during the transient part of the computation, until a prescribed pressure distribution is achieved on the blade surfaces.
The method is applied to the design of a centrifugal compressor impeller, whose hub endwall and blade surfaces are modified by the inviscid inverse method. The real performance of both initial and modified geometries are compared through three-dimensional Navier-Stokes computations.
Cost Effective Maintenance of Gas Turbine Machinery in Swedish Navy Fast Surface Attack Ships
Authors: Löfdahl Jan-Olof 
Published: December 2014

This paper is a summary of 35 years experience from maintenance, overhaul and repair of the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy.
The 54 installed PROTEUS Gas Turbines in 18 ships have accumulated nearly 300 000 running hours. The reliability has steadily improved thanks to careful monitoring and intensive improvement programs.
The initial, less than 500 hours average between engine removals has been extended to nearly 3000 hours as of today. Also the number of catastrophic engine failures has decreased.
Although the Spare Parts prices and the Labor Costs per hour have increased over the years the maintenance cost per fired Gas Turbine hour has decreased.
The paper describes the technical and economical aspects together with the cost reducing efforts. The information derives from the Swedish Navy Maintenance and Failure Reporting System, named “MARIS”, and from the VOLVO overhaul workshop annual technical and economical activity report.
Coal-Biomass Gasification in a Pressurized Fluidized Bed Gasifier
Authors: de Jong W. , Andries J. , Hein K. R. G. 
Published: December 2014

In the framework of a multi-national European Joule project, experimental research and modeling concerning co-gasification of biomass and coal in a bubbling pressurized fluidized bed reactor is performed. The impact of fuel characteristics (biomass type, mixing ratio) and process conditions (pressure, temperature, gas residence time, air-fuel ratio and air-steam ratio) on the performance of the gasifier (carbon conversion, fuel gas composition, non-steady state behaviour) was studied experimentally and theoretically.
Pelletized straw and miscanthus were used as biomass fuels. The process development unit has a maximum thermal capacity of 1.5 MW and was operated at pressures up to 10 bar and bed temperatures in the range of 650 °C–900 °C. The bed zone of the reactor is 2 m high with a diameter of 0.4 m and is followed by an adiabatic freeboard, approximately 4 m high with a diameter of 0.5 m.
Time-averaged as well as time-dependent characteristics of the fuel gas were determined experimentally. The results will be compared with the gas turbine requirements provided by a gas turbine manufacturer, one of the partners in the project. The evaluation of the results will ultimately be used to implement and test an adequate control strategy for the pressurized fluidized bed gasifier integrated with a gas turbine combustion chamber.
Dynamic Modeling and Control of Regenerative Gas Turbines
Authors: Camporeale S. M. , Fortunato B. , Dumas A. 
Published: December 2014

A non linear dynamic model has been developed in order to simulate the dynamic behavior of single-shaft or multi-shaft regenerative gas turbines. The aim of the work is to provide a fast and reliable model for the synthesis of the controllers and the study of critical dynamic situations. Some significant features characterize the proposed model:
- an efficient one-dimensional model is used in order to properly model a stationary counter-flow regenerator;
- a stage by stage model is provided for the air cooled turbine expansion in order to take into account the blade thermal transients.
The mathematical model and the numerical methodology are described in the paper.
A single-shaft regenerative cycle gas turbine is analyzed. In order to design a multivariable controller for this plant, a linearized model is developed from the non-linear model. The gas turbine is described by the transfer functions that relate the input variables (fuel rate and variable inlet guide vanes) to the state variables (shaft speed and turbine output temperature). Accuracy and effects of non-linearities are described.
Experiences From the Joint Development of the GTX100 Turbine Blading
Authors: Gudmundsson Bengt , Nilsson Ulf , Linder Ulf , Shukin Sergey , Afanasiev Igor , Kostege Valery 
Published: December 2014

The GTX100 is the most recent industrial gas turbine in the ABB fleet. The development of the GTX100 turbine blading was a joint project involving four companies. A thorough evaluation of various design requirements resulted in the selection of a single shaft three-stage turbine configuration.
The cooling techniques employed for the blading are based on the knowledge from the Russian school of design for gas turbines. These techniques have been verified by a considerable amount of experimental data and field experience over a number of years. To incorporate western manufacturing methods, western suppliers were introduced at an early stage in the development.
Most of the engineering development of the turbine blading was carried out in Russia. In order to achieve efficient cooperation between Russia and Sweden, specialists from both companies were stationed at alternating companies. The verification of the turbine design is divided into two steps. The first step is cold and hot component testing and the second is the overall engine testing.