bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recurrent Aphthous Stomatitis in Childhood and Adolescence: A Single‐Center Experience
Authors: Gürkan Asuman , Özlü Sare Gülfem , Altıaylık‐Özer Pınar , Kurtul Bengi Ece , Karacan Can Demir , Şenel Saliha 
Published: April 2015

AbstractBackgroundRecurrent aphthous stomatitis (RAS) is a common oral ulcerative condition in children. The objective was to describe the clinical features of RAS in children with accompanying clinical and laboratory findings.MethodsThe study included 120 patients younger than 18 years of age (mean age 9.6 ± 4.3 years) with three or more oral aphthous ulcers per year between August 2008 and February 2014. Demographic characteristics of the patients, clinical features of the ulcers, and associated clinical and laboratory findings were evaluated.ResultsThe mean number of aphthae per year was 12.8 ± 8.5 and the mean duration of the disease was 3.6 ± 2.9 years. Minor aphthae were the most common type (87%), papulopustules were the most common accompanying cutaneous lesions (13.3%), and family history of RAS was the most common associated factor (35.8%). Genital scarring (p = 0.04) and pathergy (p = 0.01) were significantly more common in the adolescent group. Pathergy was significantly related to genital scarring (p = 0.04) and Behçet's disease (p = 0.02). There was no association between the number of aphthae per year and the duration of the disease and hematologic and immunologic abnormalities.ConclusionOur study is consistent with previous reports in terms of clinical features of aphthous ulcers, related diseases, and family history of RAS, but no associated laboratory abnormalities were noted.
Is Patch Testing with Food Additives Useful in Children with Atopic Eczema?
Authors: Catli Gonul , Bostanci Ilknur , Ozmen Serap , Dibek Misirlioglu Emine , Duman Handan , Ertan Ulker 
Published: April 2015

AbstractBackgroundAtopy patch testing is a useful way to determine delayed‐type hypersensitivity reactions to foods and aeroallergens. Although food additives have been accused of worsening atopic eczema symptoms, according to recent studies the role of food additives in atopic eczema remains unclear. The purpose of our study was to investigate food additive hypersensitivity in a group of children with atopic eczema by using standardized atopy patch testing and to determine the role of food additive hypersensitivity in atopic eczema.MethodsThirty‐four children with atopic eczema and 33 healthy children were enrolled in the study. Children who consumed foods containing additives and did not use either antihistamines or local or systemic corticosteroids for at least 7 days prior to admission were enrolled in the study. All children were subjected to atopy patch testing and after 48 and 72 hours their skin reactions were evaluated by using the guidelines.ResultsPositive atopy patch test results were significantly higher in the atopic eczema group. Forty‐one percent of the atopic eczema group (n = 14) and 15.2% (n = 5) of the control group had positive atopy patch test results with food additives (p = 0.036) (estimated relative risk 1.68, case odds 0.7, control odds 0.17). Carmine hypersensitivity and the consumption of foods containing carmine, such as gumdrops, salami, and sausage, were significantly higher in the children with atopic eczema.ConclusionThis is the first study investigating hypersensitivity to food additives in children with atopic eczema. Our results indicate that carmine may play a role in atopic eczema.
Effectiveness of insecticide‐treated and untreated nets to prevent malaria in India
Authors: Van Remoortel Hans , De Buck Emmy , Singhal Maneesh , Vandekerckhove Philippe , Agarwal Satya P. 
Published: April 2015

AbstractObjectivesIndia is the most malaria‐endemic country in South‐East Asia, resulting in a high socio‐economic burden. Insecticide‐treated or untreated nets are effective interventions to prevent malaria. As part of an Indian first‐aid guideline project, we aimed to investigate the magnitude of this effect in India.MethodsWe searchedMEDLINE, Embase and Central to systematically review Indian studies on the effectiveness of treated or untreatedvs. no nets. Parasite prevalence and annual parasite incidence served as malaria outcomes. The overall effect was investigated by performing meta‐analyses and calculating the pooled risk ratios (RR) and incidence rate ratios.ResultsOf 479 articles, we finally retained 16 Indian studies. Untreated nets decreased the risk of parasite prevalence compared to no nets [RR0.69 (95%CI; 0.55, 0.87) in high‐endemic areas,RR0.49 (95%CI; 0.28, 0.84) in low‐endemic areas], as was the case but more pronounced for treated nets [RR0.35 (95%CI; 0.26, 0.47) in high‐endemic areas, risk ratio 0.16 (95%CI; 0.06, 0.44) in low‐endemic areas]. Incidence rate ratios showed a similar observation: a significantly reduced rate of parasites in the blood for untreated netsvs. no nets, which was more pronounced in low‐endemic areas and for those who used treated nets. The average effect of treated nets (vs. no nets) on parasite prevalence was higher in Indian studies (RR0.16–0.35) than in non‐Indian studies (data derived from a Cochrane systematic review;RR0.58–0.87).ConclusionsBoth treated and untreated nets have a clear protective effect against malaria in the Indian context. This effect is more pronounced there than in other countries.
The Effect of Thermal Transients on Radial Turbine Blade Vibration Damping: A Case Study
Authors: Næss Tore , Teien Kjell O. 
Published: April 2015

Since the Kongsberg KG5 gas turbine was introduced into service in 1977 these engines have accumulated more than 100 000 hours of field operation. Apart from an exducer blade vibration problem which was revealed and fixed prior to field introduction, no major operational problems have been encountered.
During test and commissioning of two larger orders, three separate incidents of turbine blade failure occurred, one in March 1982 and two in February 1983. The first incident triggered a number of investigative actions and the resulting conclusion was confirmed by the last two incidents.
The present paper describes the analytical and test methods employed in order to investigate this problem. The blade natural frequencies were determined analytically through a NASTRAN analysis and experimentally with a TV-Speckle Interferometer technique.
It is shown how the influence of an interference fit or dampening joint between the two rotor wheels was actually hiding the possible resonance condition during the initial qualification tests, and how the transient movements of this joint would allow resonance to occur under certain operational conditions.
The possible corrective modifications are discussed and the selected solution is shown. The test set up and the results from the verifying strain gauge test is presented.
Comparative Analysis of Gas Turbine Systems for Pressure Energy Recovery From Blast Furnace Gas
Authors: Guizzi Giuseppe Leo 
Published: April 2015

Modern high capacity blast furnaces are generally operated at high values of back pressure at the top of the furnace (250÷400 kPa abs.). In order to recover this large quantity of pressure energy some turbine equipments have been recently developed. The possible solutions of these systems must take into account the clean up outcoming blast furnace gas conditions (cold and water saturated gas).
Up-to-date solution analysis has carried to three different main process types: wet expansion; dry expansion by partial burning of gas; dry expansion by gas heating in a heat exchanger.
This paper develops an energy based analysis for these equipments taking into account not only the recovery in the turbine unit, but also the effect of this equipment on the whole integrated system “blower - cowpers - blast furnace - gas turbine unit - power conversion station”.
A parametric analysis is performed and the obtained results are presented and discussed.
Cascade Heat Transfer Tests of the Air Cooled W501D First Stage Vane
Authors: Tobery E. Wayne , Bunce Richard H. 
Published: April 2015

A full scale, three vane, four passage, first stage stator segment from a Westinghouse W501D engine was tested in the vane cooling cascade rig at the Combustion Turbine Systems Division Development Center in Concordville, Pennsylvania. The cascade facility operates with air preheated to engine compressor discharge conditions, and it is fired with a standard combustor and nozzle assembly so that engine design vane inlet temperatures and pressures may be obtained with realistic free stream turbulence levels. The vanes are cooled internally by impingement inserts over most of the surface, and with pin fins in the trailing edge region. External film cooling is introduced by discrete jets over most of the suction surface and over the aft portion of the pressure surface. The flow to each insert was individually controlled and measured for the test.
Tests were run over a range of cascade pressures, temperatures, and Reynolds’ numbers. The vanes were instrumented to obtain metal temperatures, internal cooling air temperatures and pressures, and gas path static pressure near the film cooling holes. Measured metal temperatures were compared to analytical predictions over the range of test conditions. Since internal heat transfer relations had been obtained by model tests, a good correlation between measured and predicted temperatures verified the gas path side heat transfer coefficients used in the design and analysis.
Off-Design and Part-Load Behaviour of PFBC Combined Cycle Power Plant
Authors: Pillai K. K. , Roberts A. G. 
Published: April 2015

Combined cycle power plant utilising pressurised fluidised bed coal combustors (PFBCs) have, of necessity, to be designed to suit the particular gas turbine chosen. The gas turbine characteristics set not only the design point but also the turndown available. The interactions between the gas cycle, the combustor and the steam cycle are different to those normally associated with combined cycle plant.
This paper describes the methods available when designing for plant operation at off-design conditions. It is shown how available techniques are capable of meeting commercial plant requirements for start-up, rates of load change and turndown.
Indirect Fired Gas Turbine Cogeneration Using Petroleum Coke Fired AFBC Air Heater
Authors: Stäb F. P. , Moskowitz S. 
Published: April 2015

A cogeneration plant based on a Combined Cycle (C.C.) system offers advantages especially when an in-expensive fuel can be used. Petroleum coke as a by-product solid fuel with high sulfur content can be fired in an Atmospheric Fluid Bed Combustion Air Heater (AFBC-AH) to provide indirect heating of the compressor discharge air flow of the gas turbine in such a C.C. system, which produces electric power and process steam in an efficient and environmentally clean manner.
This paper describes (a) the overall system and some major components, (b) system performance and (c) the economics of such a plant for an application on a site, where petroleum Coke is already used as raw material in the industrial process.
The paper shows that for this particular application the C.C. cogeneration plant with a petroleum coke fired AFB air heater can be competitive when compared with the natural gas or liquid fuel fired cogeneration plant. In addition, this plant will generate less emissions than generally achieved in solid fuel fired cogeneration plants.
Experimental Study of the Flow Field Behind an Annular Turbine Nozzle Guide Vane With and Without Downstream Rotor
Authors: Boletis E. , Sieverding C. H. 
Published: April 2015

Measurements of the three dimensional flow field in annular turbine nozzle guide vanes present an important step in the simulation of the real flow conditions in turbomachinery bladings. This paper seeks to determine whether the installation of a rotor closely behind a high hub-to-tip ratio cascade (DH/DT=0.8) is indispensable for establishing correct flow conditions at the cascade exit or whether the use of an axial diffuser of a certain length is sufficient. Also, an attempt is made to separate the possible effects of the rotor blades from that of the rotating rotor disc.
The tests are carried out on a low speed, low aspect ratio, high turning nozzle guide vane. The flow is explored by means of a double head four-hole pressure probe and the results are presented in the form of contour plots and spanwise pitch-averaged distributions of losses, flow angles and static pressure.
Design and Testing of a 45 HW Gas Turbine
Authors: Wicki A. , Farkas F. 
Published: April 2015

A new medium size gas turbine in the 45 MW range (Type 8) has been designed, manufactured and tested. Although the components that have proven to be successful over years of practical experience were kept, definite improvements with respect to the thermodynamic process have been achieved.
All new components were designed with the help of the latest analytical equipment. Major components were tested separately and on models built to scale.
To test the entire machine, a power plant equipped with extensive measuring instrumentation was built. The test results agree widely with the design values.
Design of a Heat Recovery Steam Generator
Authors: Logeais David R. 
Published: April 2015

A gas turbine in the size range of 20,000 hp (14.9 MW) was retrofitted with a heat recovery steam generator (HRSG). The HRSG produces high pressure superheated steam for use in a steam turbine. Supplementary firing is used to more than double the steam production over the unfired case.
Because of many unusual constraints, an innovative design of the HRSG was formulated. These design constraints included:
1. A wide range of operating conditions was to be accommodated.
2. Very limited space in the existing plant.
3. A desire to limit the field construction work necessary in order to provide a short turn-around time.
This paper will discuss the design used to satisfy these conditions.
Application of Gas Turbine Generators for Preheating Combustion Air With Conventional Boilers or Furnaces
Authors: Davidse J. , Roukema J. 
Published: April 2015

This paper will describe a co-generation system using a conventional boiler or process heater and applying a gas turbine to provide preheated combustion air to the boiler or furnace.
A number of design considerations such as applicable type and size of the gas turbine, expected energy savings and control and safety aspects are discussed. These design considerations should be taken into account when retrofitting a conventional plant into a co-generation system.
The paper will also describe such a type of co-generation system with a process heater which is in operation at the Chevron/Texaco Refinery in The Netherlands.
Examination of Coal and Ash Samples by PIXE Method for Gas Turbine Applications
Authors: Raj S. , Raj R. , Hall G. 
Published: April 2015

A new technique, PIXE - Particle Induced X-Ray Emission, for analyzing concentration of trace elements with a detection concentration in parts per million is presented in this paper.
PIXE is performed on a sample by using a proton beam. The experimental results are obtained from a number of coal and ash samples useful for the combined cycle power plants. The technique is useful for deposit analysis and analysis of eroded and corroded surfaces. This technique can identify depth of deposit and chemical constituents simultaneously.
An Investigation of the Transverse Velocity Profile in the Case of Internal Viscous Aerodynamic Problems
Authors: Kotidis P. , Chaviaropoulos P. , Papailiou K. D. 
Published: April 2015

The development of transverse velocity profile is directly related to the development of secondary vorticity. In the internal aerodynamics case with potential external flow, although vorticity remains confined inside the viscous shear layer, secondary vorticity induced velocities exist outside of it.
If the secondary vorticity field is known, the induced secondary velocity field is well approximated following Hawthorne’s classical analysis. In the present work, the above analysis is used to separate the velocity field in the transverse plane into a potential and a rotational part. In the case of confined flows, the rotational part is confined inside the viscous shear layer, while the potential part occupies the whole flow field. This last part is the consequence of the “displacement” effects of the shear layer in the transverse plane.
Therefore, the present work allows a re-examination of the flow two-zone model (separation of the flow field in a viscous and an inviscid part) in confined flows.
On the other hand, the limitations of Hawthorne’s theory are examined, while a parallel analysis is presented for the case where the secondary vorticity distribution varies not only along the blade height, but also circumferentially.
Accuracy and Convergence Characteristics of Steady Transonic Potential Flow Solutions
Authors: Ecer A. , Yurtseven H. O. , Karaca C. 
Published: April 2015

This paper discusses the importance of artificial viscosity in analyzing transonic potential flows in terms of:
•convergence characteristics of a relaxation scheme, and
•accuracy of the obtained solutions.
In this first part of the paper, two types of relaxation schemes are discussed where different types of damping terms are employed. The utilization of artificial viscosity for these different procedures are studied. In the second part, the accuracy of solutions obtained by employing artificial viscosity is investigated, in particular for the solution around a shock. Finally, it is suggested that comparison of solutions with different levels of artificial viscosity may be an efficient tool in determining the accuracy of the obtained solution.
A Study of the Prediction of Tip and Seal Clearances and Their Effects in Gas Turbine Transients
Authors: Pilidis P. , Maccallum N. R. L. 
Published: April 2015

Clearances of compressor and turbine blade tips and seals alter during and following speed transients. These changes affect the performance of the components and hence of the engine.
This paper describes models for the prediction of blade tip clearance changes and seal clearance changes. These models have been applied to the H.P. Compressor and H.P. Turbine and to two seals controlling air flows in a Two-spool Bypass Engine. The predicted acceleration rates appear to be more influenced by the changes in the seal clearances than by the tip clearance changes.
The increases in computing time in the engine transient program which result from inclusion of the model are acceptable.
Simplified Method for Flow Analysis and Performance Calculation Through an Axial Compressor
Authors: Miton Hubert , Doumandji Youssef , Chauvin Jacques 
Published: April 2015

This paper describes a fast computation method of the flow through multistage axial compressors of the industrial type. The flow is assumed to be axisymmetric between the blade rows which are represented by actuator disks. Blade row losses and turning are calculated by means of correlations.
The equations of motion are linearized with respect to the log of static pressure, whose variation along the radius is usually of limited extent for the type of machines for which the method has been developed.
In each computing plane (i.e. between the blade rows) two flows are combined: a basic flow with constant pressure satisfying the mass flow requirements and a perturbation flow fulfilling the radial equilibrium condition.
The results of a few sample calculations are given. They show a satisfactory agreement with a classical duct flow method although the computing time is reduced by a factor five.
The method has also been coupled with a surge line prediction calculation.
Very High Efficiency Small Nuclear Gas Turbine Power Plant Concept (HTGR-GT/BC) for Special Applications
Authors: McDonald C. F. , Cavallaro L. , Kapich D. , Medwid W. A. 
Published: April 2015

To meet the energy needs of special terrestrial defense installations, where a premium is placed on high plant efficiency, conceptual studies have been performed on an advanced closed-cycle gas turbine system with a high-temperature gas-cooled reactor (HTGR) as the heat source. Emphasis has been placed on system compactness and plant simplicity. A goal of plant operation for extended periods with no environmental contact had a strong influence on the design features. To realize a high plant efficiency (over 50%) for this mode of operation, a combined cycle was investigated. A primary helium Brayton power conversion system coupled with a Freon bottoming cycle was selected.
The selection of a gas turbine power conversion system is very much related to applications where high efficiency is paramount and this can be realized with the utilization of a cold heat sink. Details are presented of the reactor arrangement, power conversion system, major components, installation, and performance for a compact nuclear power plant currently in a very early stage of concept definition.
Validation of Flow Coefficients Measurement by Laser Velocimeter in Straight-Through Labyrinth Seal Models With Full Size Test Rig Results
Authors: D’Emilia Giulio 
Published: April 2015

In the computation of overall efficiency in turbomachines the increase of performance in high pressure centrifugal compressors renders of great importance the rôle of leakage in straight-through labyrinth seals.
A test rig for labyrinth seals used in process compressors was built in order to carry out a systematic study of the fluidodynamic phenomena characteristic of flow in these devices.
Full size seals were tested under different working conditions and the results were utilized for a quantitative definition of the experimental coefficients introduced in previsional methods which were shown the best ones on the basis of previous investigation (1).
The coefficients consider the principal fluidodynamic phenomena existent in the seals: fluid flow contraction in the throttlings and kinetic energy carry-over, which have contrasting effects on the leakage of a straight-through labyrinth seal.
The results were used to find elements of correct design in these seals. They point out besides the geometric parameters which optimize seal performance, minimizing the leakage on a fixed length of the labyrinth.
Larger scale models of the same seals tested on the above mentioned test rig were studied in a smoke tunnel under conditions which satisfied the Reynolds similarity.
This experimental set-up permitted the measurement of the velocity distributions within the straight through labyrinth seal models by means of a laser Doppler velocimeter.
Particular attention was dedicated to the definition of uncertainty of the experimental coefficients. The information obtained was satisfactory.
The results showed promising correlations between real seals and larger models. These relations could be very useful when designing labyrinth seals for centrifugal compressors, as a large part of long, costly tests on real seals could be substituted by faster and more economical measurements on models.