bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased libido associated with donepezil treatment: a case report
Authors: Segrec Nusa , Zaman Rashid , Pregelj Peter 
Published: March 2015

AbstractInappropriate verbal and physical sexual behaviour is not common among individuals with dementia, but when it does occur, it can have profound consequences. We report a case of 79‐year‐old woman with dementia of the Alzheimer's type who complained of increased libido after an increased dose of donepezil, which was being used along with tianeptine. Donepezil withdrawal led to the resolution of increased libido, but when it was reintroduced, increased libido reappeared once again (Naranjo score: 7). Increased libido was not reported by the patient during the 6‐year follow‐up period after donepezil withdrawal. A potential mechanism of acetylcholinesterase inhibitor‐induced increased libido and the current literature on hypersexuality as a side‐effect of donepezil treatment are discussed.
Do Household Surveys Give a Coherent View of Disability Benefit Targeting?: a Multisurvey Latent Variable Analysis for the Older Population in Great Britain
Authors: Hancock Ruth , Morciano Marcello , Pudney Stephen , Zantomio Francesca 
Published: March 2015

SummaryWe compare three major UK surveys, the British Household Panel Survey, Family Resources Survey and the English Longitudinal Study of Ageing, in terms of the picture that they give of the relationship between disability and receipt of the attendance allowance benefit. Using the different disability indicators that are available in each survey, we use a structural equation approach involving a latent concept of disability in which probabilities of receiving attendance allowance depend on disability. Despite major differences in design, once sample composition has been standardized through statistical matching, the surveys deliver similar results for the model of disability and receipt of attendance allowance. Provided that surveys offer a sufficiently wide range of disability indicators, the detail of disability measurement appears relatively unimportant.
A Bayesian Quantile Regression Model for Insurance Company Costs Data
Authors: Sriram Karthik , Shi Peng , Ghosh Pulak 
Published: March 2015

SummaryWe examine the average cost function for property and casualty insurers. The cost function describes the relationship between a firm's minimum production cost and outputs. A comparison of cost functions could shed light on the relative cost efficiency of individual firms, which is of interest to many market participants and has been given extensive attention in the insurance industry. To identify and to compare the cost function, current practice is to assume a common functional form between costs and outputs across insurers and then to rank insurers according to the centre of the cost distribution. However, the assumption of a common cost–output relationship could be misleading because insurers tend to adopt different technologies that are reflected by the cost function in their production process. The centre-based comparison could also lead to biased inference especially when the cost distribution is skewed with a heavy tail. To address these issues, we model the average production cost of insurers by using a Bayesian quantile regression approach. Quantile regression enables the modelling of different quantiles of the cost distribution as opposed to just the centre. The Bayesian approach helps to estimate the cost-to-output functional relationship at a firm level by borrowing information across firms. In the analysis of US property–casualty insurers, we show that better insights into efficiency are gained by comparing different quantiles of the cost distribution.
Current Status of 300kW Industrial Ceramic Gas Turbine R&D in Japan
Authors: Honjo Kaoru , Hashimoto Ryosaku , Ogiyama Hisao 
Published: March 2015

This paper gives an overview of the current status of Japan’s national industrial ceramic gas turbine (CGT) project.
The goals are 42% and higher thermal efficiency at the turbine inlet temperature (TIT) of 1350°C, and the emission from the exhaust gas should meet the regulatory values (for example, 70ppm for NOx). Also, ceramic material properties have the goals of 400 MPa for the minimum guaranteed strength at 1500°C, and 15 MPa m for the fracture toughness.
Currently, the basic metal gas turbine of TIT 900°C with all metallic components has already been fabricated and is running under some test conditions. The design of the basic ceramic gas turbine of TIT 1200°C has been completed and its manufacture is in progress. Research is addressing the production of large, complicated ceramic parts, and parts which have less deformation and defects can now be produced.
The Influence of Adjustable Inlet Guide Vanes on the Performance of Multi-Stage Industrial Centrifugal Compressors
Authors: Lüdtke Klaus 
Published: March 2015

Not only single-stage but also multi-stage centrifugal process compressors are often equipped with one row of adjustable Inlet guide vanes before the first stage.
The question, frequently asked by the rotating equipment purchaser is whether such an expensive component is justified for multi-stage centrifugal compressors, since it effects first stage head only. Does or does it not improve turn-down or power consumption in comparison with ordinary butterfly valva suction throttling? The paper examines if and to what degree the favorable turn-down and part-load power consumption of IGV-equipped single-stage machines can be transferred to multi-stage compressors.
An intuitive answer of-course is: the lower the number of stages, the more advantageous is the IGV-equipped compressor. There are however other influential parameters like molecular weight of the gas, Mach number, number of intercoolers and others.
In contrast to axial and integral gear compressors centrifugal single-shaft compressors cannot be equipped with adjustable IGV’s before each stage due to an extreme lack of interstage space dictated by rotordynamic requirements. The maximum number of IGV’s is two for back-to-back arranged centrifugal impellers.
Recess Vane Passive Stall Control
Authors: Ziabasharhagh M. , McKenzie A. B. , Elder R. L. 
Published: March 2015

An experimental investigation has been carried out on the influence of a vaned recessed casing treatment on the stall margin improvement of axial flow fans with different hub to tip ratio, with and without inlet distortion.
The inlet distortion tests were conducted on a 0.5 hub to tip ratio fan and significant increases in the flow range with only small drops in operating efficiency were observed.
The clean flow tests were conducted on higher hub to tip ratio fans (0.7 and 0.9). In each case the stage characteristic was compared with the results obtained with a solid casing. Significant increases in the flow range, with only modest or no loss in operating efficiency, were observed for optimum configurations at both diameter ratios.
Influence of a Thermal Barrier Coating on the Performance of a Turboprop Engine
Authors: MacLeod J. D. , Laflamme J. C. G. 
Published: March 2015

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada has evaluated the influence of applying a thermal barrier coating on the performance of a gas turbine engine. The effort is aimed at quantifying the performance effects of a particular ceramic coating on the first stage turbine vanes. The long term objective of the program is to both assess the relative change in engine performance and compare against the claimed benefits of higher possible turbine inlet temperatures, longer time in service and increased time between overhauls. The engine used for this evaluation was the Allison T56 turboprop with the first stage turbine nozzles coated with the Chromalloy RT-33 ceramic coating.
The issues addressed in testing this particular type of hot section coating were;
1) effect of coating thickness on nozzle effective flow area;
2) surface roughness influence on turbine efficiency;
This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. Discussed are performance variations due to coating thickness and surface roughness on engine performance characteristics. As the performance changes were small, a rigorous measurement uncertainty analysis is included. The coating application process, and the affected overhaul procedures are examined. The results of the pre- and post-coating turbine testing are presented, with a discussion of the impact on engine performance.
Hot Corrosion Resistance of Thermal Barrier Coatings
Authors: Nagaraj B. A. , Maricdcchi A. F. , Wortman D. J. , Patton J. S. , Clarke R. L. 
Published: March 2015

The hot corrosion resistance of yttria stabilized zirconia (YSZ) thermal barrier coatings was evaluated using an atmospheric burner rig. The coatings were deposited by plasma spraying and electron beam physical vapor deposition (EB-PVD). The tests were performed for up to 2000 hours at 1700°F and 1300°F. The test parameters were designed to simulate the deposit chemistry and corrosion microstructures observed in marine gas turbine engines. The YSZ coating performed very well in the tests, with no spallation and little bond coat corrosion.
Plasma sprayed YSZ coating was also evaluated by engine testing in a hot corrosive environment. Post test evaluation showed virtually no corrosion of the ceramic or the bond coat. Parts that were not ceramic coated had undergona severe corrosion. The results are discussed in terms of coating microstructures and the chemistry of the environment.
A System Dynamics Approach to Modeling Gas Turbine Combustor Wear
Authors: Bagepalli B. , Dinc S. , Imam I. , Barnes J. , Slocum C. 
Published: March 2015

This paper deals with the development of the basic understanding of dynamic and wear problems of combustor systems. A system dynamic modeling approach has been developed using a general purpose dynamic/wear analysis program (Mechanism Analysis Program, MAP), and excellent validation has been achieved via laboratory tests. The objective is to develop a generic design/analysis tool, both, for quick evaluation of preliminary designs, and for detailed design studies to create improved/optimized combustor designs from a wear/life perspective.
Dynamic simulations of two different designs are run: Many worn field samples are available for one design, and laboratory test results for the other. The wear patterns on the former are matched very well by the analytical model. Excellent correlation, too, is obtained with the dynamic (accelerometer) measurements on the latter. It is, now, possible to isolate system dynamic causes (such as resonance) from material related ones (such as hardness) when designing for long life.
Viscous Flows in Centrifugal Compressor Diffusers at Transonic Mach Numbers
Authors: Teipel I. , Wiedermann A. , Evers W. 
Published: March 2015

A numerical investigation of steady two- and three-dimensional flow fields in vaned diffusers of highly-loaded centrifugal compressors is described. The explicit MacCormack scheme was used to calculate inviscid and viscous effects because of the possibility of vectorization. Transonic Mach numbers are reached in the entrance of the diffuser and therefore time-dependent equations are solved. Two methods are employed to accelerate convergence of this explicit scheme. These techniques are (1) local time stepping and (2) applying a multigrid scheme. For the turbulent case an improved Baldwin-Lomax model given by Granville has been used.
The numerical procedure has been used to compute two-dimensional transonic flow fields of a centrifugal compressor diffuser at different impeller speeds. It is shown that the predicted pressure field is in reasonable agreement with experimental data. Different approaches for the evaluation of global loss figures have been compared with each other. In addition, an evaluation of the complete three-dimensional Navier-Stokes equations is presented. The vanes in the diffuser are twisted such that the flow field contains a strong three-dimensional effect. Again a comparison with experiments is carried out and the agreement is fairly good.
A Wide-Range Axial-Flow Compressor Stage Performance Model
Authors: Bloch Gregory S. , O’Brien Walter F. 
Published: March 2015

Dynamic compression system response is a major concern in the operability of aircraft gas turbine engines. Multi-stage compression system computer models have been developed to predict compressor response to changing operating conditions. These models require a knowledge of the wide-range, steady-state operating characteristics as inputs, which has limited their use as predicting tools.
The full range of dynamic axial-flow compressor operation spans forward and reversed flow conditions. A model for predicting the wide flow range characteristics of axial-flow compressor stages was developed and applied to a 3-stage, low-speed compressor with very favorable results and to a 10-stage, high-speed compressor with mixed results.
Conclusions were made regarding the inception of stall and the effects associated with operating a stage in a multistage environment. It was also concluded that there are operating points of an isolated compressor stage that are not attainable when that stage is operated in a multi-stage environment.
Combined-Closed Gas Cycles for Terrestrial, Marine and Space Nuclear Power Systems
Authors: Tilliette Z. P. 
Published: March 2015

Higher temperature nuclear heat sources are becoming available and more efficient energy conversion systems can be proposed, namely Brayton-Rankine combined cycles which are presently very successful in the terrestrial fossil power plants market. A combined gas-steam cycle adaptation to the now being developed high temperature gas-cooled reactor MHTGR is presented. In order to avoid serious problems associated with the direct cycle, the concept features a He/He heat exchanger and a steam generator heated in series. Consequences are a significant plant efficiency increase, a sufficiently low reactor inlet temperature, attractive operating conditions and a possible reduction of the reactor water ingress hazard.
Similar, judiciously simplified arrangements could be contemplated for possible future efficient marine nuclear power plants.
Cycle combinations could also offer new, suitable approaches of space power systems, particularly for Lunar or Martian bases. A bottoming gas cycle could be a dramatic booster of a topping static thermionic converter, provided that a significantly larger radiator area be acceptable. Combined Brayton-Rankine cycles are also possible candidates for Moon or Mars surface power systems. As a consequence, should a gas-cooled reactor be used as the heat source in a direct cycle arrangement, its design could be drastically simplified.
Applications Using Dry Gas Seals to Control Axial Shaft Loads in Centrifugal Compressors
Authors: Bear C. C. , Gibson S. W. 
Published: March 2015

Dry gas seal technology has developed significantly over the past two decades. In addition to advances in standard seal technologies, alternate configurations of dry gas seals within the compressor have provided compressor efficiency improvements among other benefits. This paper describes the innovative application of dry gas seals in the reduction and control of axial shaft forces in pipeline gas compressors.
By uniquely configuring the dry seals, the balance piston was removed from a beam type compressor, resulting in improvement of the compressor efficiency. In addition, the maximum axial forces in an overhung unit were substantially lowered, eliminating full pressure start-up problems, and allowing the practical installation of magnetic bearings. In both beam and overhung compressor applications, these dry seals combined with a control system reduce axial forces on the shaft to zero under most operating conditions.
Ignition and Exhaust Emission Characteristics of Spray Combustion in a Pre-Chamber Type Vortex Combustor
Authors: Ohkubo Youichirou , Nomura Yoshihiro , Idota Yoshinori , Gunji Yoshihisa 
Published: March 2015

The lean ignition limit, the lean blowout limit and the exhaust emission characteristics of spray combustion have been investigated experimentally using a pre-chamber type vortex combustor developed for a 300KW large-bus gas turbine engine. It has been verified that these depend on the spray characteristics of the fuel injector and the air flow pattern or the distribution of air in the chamber.
Ignition succeeds through three processes. The first step is the formation of a flame kernel near the sparking ignitor, the second step is the propagation of the flame kernel into a flame holding region, and the last step is the formation of a rotating flame in that region. The lean blowout limit of the rotating flame depends on the air flow pattern in the pre-chamber when the air temperature in the combustor inlet is under 470K, while a constant fuel-air ratio of less than 0.001 is maintained at 470K and above. With no or a little secondary air, the NOx emission index does not increase in proportion to the fuel-air ratio, because both the gas temperature and residence time decrease due to the radiative heat loss caused by soot formation and reduction of a recirculation region in the main-chamber.
These phenomena were evaluated with 3 dimensional numerical simulations taking account of spray combustion, soot formation, the extended-Zeldovich thermal NO formation and radiative heat loss.
Experimental and Theoretical Investigation of a Research Atomizer/Combustion Chamber Configuration
Authors: Hassa C. , Blümcke E. , Brandt M. , Eickhoff H. 
Published: March 2015

A research airblast atomizer/combustion chamber configuration has been built for the validation of a mathematical model of two phase flows in gas turbine combustors. The inlet boundary conditions of the gas flow were measured within the nozzle by Laser-Two-Focus-Velocimetry. Starting velocities and mass fluxes for the droplet sizes of the spray were measured by Phase-Doppler-Anemometry at a plane 7mm downstream of the atomizer lip. Gas- and drop velocities were measured consecutively in the confined swirling isothermal flow throughout the combustor and were compared with the results of a newly developed mathematical model of spray dispersion.
The spray shows the general structure of an axial acceleration of all dropsizes and a following dispersion of the droplets and radial separation by centrifugal forces according to their size. Measured and calculated drop velocities for 10, 30 and 50μm drops compare well, except for some differences, which can be explained by deficiencies of the gas flow calculation. Mass flux and volumetric mean diameter profiles are also correctly reproduced.
Phasing the Construction of an IGCC Plant for Fuel Flexibility
Authors: Dechamps P. J. , Mathieu Ph. 
Published: March 2015

The Integrated Coal Gasification in Combined Cycle technique allows a come back to coal: starting with a Combined Cycle plant, it is possible to add gasification units several years later and hence to switch from natural gas to coal. However, the price to pay will be capital cost but also a loss of performances of the resulting plant compared to a genuine Integrated Coal Gasification in Combined Cycle.
In this paper, we investigate the phasing option starting with a new Combined Cycle plant, optimized on natural gas operation, and ending with an Integrated Coal Gasification in Combined Cycle plant. We calculate the performances of the resulting plants with four types of gasifiers based on Texaco, Shell, Dow and British-Gas-Lurgi processes. We then compare the performances of these four plants with the performances of new Integrated Coal Gasification in Combined Cycle plants, optimized on coal operation and fully integrated, comprising the same four gasifiers. We finally compare the loss of performances in the four cases and recommend the selection of a gasifier type for such a phasing strategy.
Unsteady Pressure Measurements on the Rotor of a Model Turbine Stage in a Transient Flow Facility
Authors: Dietz A. J. , Ainsworth R. W. 
Published: March 2015

This paper describes unsteady pressure measurements made on the mid span suction and pressure surfaces of a rotating turbine blade in a transient facility. The measurements were made at the engine representative conditions for this turbine using high spatial density surface mounted semi-conductor transducers. This high spatial density, coupled with the wide bandwidth capability of the sensors and data acquisition system, has enabled analyses of unsteady wave propagation effects (both in magnitude and phase) to be carried out. This paper significantly adds to the body of data available at engine representative conditions, particularly in terms of compressibility.
Distinctions are drawn between events which are propagating at free stream velocities and those which move at local acoustic velocities. Comparisons are made with theories which have been previously expounded, and some inconsistencies are outlined.
Turbine Blade Vibration Monitoring System
Authors: Kawashima T. , Iinuma H. , Wakatsuki T. , Minagawa N. 
Published: March 2015

This paper describes a development and an evaluation of an optical blade vibration monitoring system applicable to gas turbine engine high pressure turbine blading.
The system uses high intensity He-Ne lasers, optical fibers and associated electronics, and can monitor rotor blade vibration under engine running conditions. With a combined water and air probe cooling system, it can be used for monitoring turbine blade vibration at 1300 degree C range gas temperature.
The system was applied to actual gas turbine engines and has demonstrated it’s effectiveness as a useful tool for gas turbine blade vibration evaluation.
Aerodesign and Performance Analysis of a Radial Transonic Impeller for a 9:1 Pressure Ratio Compressor
Authors: Colantuoni S. , Colella A. 
Published: March 2015

The aerodynamic design of a centrifugal compressor for technologically advanced small aeroengines requires more and more the use of sophisticated computational tools in order to meet the goals successfully at minimum cost development.
The objective of the present work is the description of the procedure adopted to design a transonic impeller having 1.31 relative Mach number at the inducer tip, 45° back-swept exit blade angle, and a tip speed of 636 m/s.
The optimization of the blade shape has been done analyzing the aerodynamic flowfield by extensive use of a quasi-3d code and a fully 3D Euler solver based on a time-marching approach and a finite volume discretization.
Testing has been done on the impeller-only configuration, using a compressor rig that simulates a real engine hardware, i.e. having an S-shape air-intake. The overall performance of the impeller are presented and discussed.