bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dipeptidyl peptidase‐4 inhibitor improves cardiac function by attenuating adverse cardiac remodelling in rats with chronic myocardial infarction
Authors: Inthachai Tharnwimol , Lekawanvijit Suree , Kumfu Sirinart , Apaijai Nattayaporn , Pongkan Wanpitak , Chattipakorn Siriporn C. , Chattipakorn Nipon 
Published: March 2015

New Findings

What is the central question of this study?
Although cardioprotective effects of dipeptidyl peptidase‐4 (DPP‐4) inhibitors have been demonstrated, their cardiac effects in chronic myocardial infarction (MI) are unclear. We determined the effects of a DPP‐4 inhibitor on cardiac function and remodelling in rats with chronic MI.

What is the main finding and its importance?
We demonstrated, for the first time, that DPP‐4 inhibitor, but not metformin, exerted similar efficacy in improving cardiac function and attenuating cardiac fibrosis compared with enalapril in rats with chronic MI. These findings reveal benefits additional to the glycaemic control by the DPP‐4 inhibitor in chronic MI, and it might become the new drug of choice for MI in patients with diabetes mellitus.

Adverse cardiac remodelling after myocardial infarction (MI) leads to progressive heart failure. Dipeptidyl peptidase‐4 (DPP‐4) inhibitors are new antidiabetic drugs that exert cardioprotection. However, their role in cardiac function and remodelling in chronic MI is unclear. We hypothesized that the DPP‐4 inhibitor vildagliptin reduces adverse cardiac remodelling and improves cardiac function in rats with chronic MI. These effects were also compared with enalapril and metformin. Male Wistar rats (n = 36) with chronic MI induced by ligation of the left anterior descending coronary artery were divided into six groups to receive vehicle, vildagliptin (3 mg kg−1 day−1), metformin (30 mg kg−1 day−1), enalapril (10 mg kg−1 day−1), combined metformin and enalapril or combined vildagliptin and enalapril for 8 weeks. At the end of the study, plasma malondialdehyde (MDA), heart rate variability (HRV), left ventricular (LV) function, pathological and biochemical studies of cardiac remodelling were investigated. Our study demonstrated that rats with chronic MI had increased oxidative stress levels, depressed HRV, adverse cardiac remodelling, indicated by cardiac fibrosis, and LV dysfunction. Treatment with vildagliptin or enalapril significantly decreased oxidative stress, attenuated cardiac fibrosis and improved HRV and LV function. We conclude that vildagliptin exerts similar cardioprotective effects to enalapril in attenuating oxidative stress and cardiac fibrosis and improving cardiac function in rats with chronic MI. Metformin does not provide these benefits in this model. Moreover, addition of either metformin or vildagliptin to enalapril does not provide additional benefit in attenuating cardiac remodelling or improving LV function compared with enalapril alone.
Preliminary Tests on an Annular Hybrid Diffuser
Authors: Montazerin N. , Adkins R. C. 
Published: April 2015

Tests have been conducted on an annular, Hybrid Diffuser, of short length while operating in isolation. The purpose was to ascertain whether such a diffuser could operate efficiently without the downstream influence of the combustor dome which had been a feature of previous tests. The diffuser was fitted with a pre-diffuser in order to raise the static pressure level of the bleed air. A series of exit cones was used as the final stage of diffusion, covering a range of included angle from 15 to 45 degrees.
Results obtained demonstrate that this configuration of Hybrid diffuser operates efficiently, that performance is improved if pressures inside the inner and outer vortex chambers are balanced, and that larger quantities of bleed must be extracted in order to maintain a high pressure recovery as the exit included angle is increased.
A Finite Element Scheme for Incompressible Viscous Flow Calculations
Authors: Cheng Wang Li , Ming Zhang Hui 
Published: April 2015

A finite element scheme for two dimensional incompressible viscous flows in primitive variables is proposed in this paper. An upwind factor finite element method is devised to solve the momentum equations, and the continuity equation is satisfied by the correction of the pressure field.
Numerical experiments are carried out for a driven cavity and a diffuser. The Renolds Number for the cavity flow is 100.0, and for the diffuser is 50000.0. The numerical result of the scheme for the cavity flow is compared with that by another numerical method and satistactory agreement is found.
Life Prediction for the Main Shaft of Aircraft Turbine Engine
Authors: Dunhui Liu 
Published: April 2015

The life prediction of the main shaft is described herein at the following three aspects: estimation of the fatigue life, testing method of the fatigue life and determination method of the service life for the main shaft. Based on the working practice, a working block diagram of life determinating procedure for the main shaft, from which the prediction contents and steps of the fatigue life for the main shaft can be seen, is also included in this paper.
Since the factors affecting the fatigue life of hardwares are very complicated, so only the main factor can be taken into consideration in the method of prediction of the life. Therefore, in this paper it is emphasized to establish a life prediction computation program which integrates the main shaft design, testing and application, so that the computation theory of the whole life prediction can be established on the foundation of the test practice and service experience.
The life of main shaft can be predicted by calculation during the design stage. The local stress method and strain empiric formula are applicable for the prediction of the main shaft life in its elastoplastic area.
A Theoretical Analysis and Experimental Study of Flow and Heat Transfer in a Transpiration Cooled Passage
Authors: Guo-Rui Huang 
Published: April 2015

In this article a theoretical analysis of the coolant flow and heat transfer in the passage for a transpiration-cooled blade was made and several mathematical expressions were led out. Various factors influenced on thermal parameters in the passage are more considered. Experimental results indicate that (1) the flow near metering orifice is not one-dimensional then it is quite important to take a correction in calculation (2) it is not appropriate to account heat transfer between the coolant and the porous shell to choice about 5 times size of the heat transfer coefficient in the turbulence tube.
This paper shows that several mathematical expressions are ready for whole heat transfer design of blades and the experimental datum are provided for the same type transpiration-cooled blade design.
Recent Developments in Vibration Monitoring and Diagnostics for Aeroderivative Gas Turbines
Authors: Adams James C. 
Published: April 2015

Industrial aeroderivative gas turbines are becoming increasingly popular for use in both on-shore and off-shore installations. The characteristics of these machines — high efficiency in simple cycle operation, small size, and light weight — make them ideal for industrial applications.
As the aeroderivative gas turbine has become more widely used, the need for more reliable monitoring methods has become increasingly apparent.
Traditional velocity transducer based seismic monitoring systems have had several shortcomings when applied to aeroderivative gas turbines. One of these problems was nuisance alarms due to increasing transducer noise output. Another was not detecting increasing casing vibration because of transducer deterioration.
Overcoming these problems has required advances in transducer technology as well as changes in signal processing techniques. This paper describes the technology and techniques used in new seismic vibration monitoring systems.
Comparison of Various Fluidized Bed Combustor-Gas Turbine Systems
Authors: Fraas Arthur P. 
Published: April 2015

Pressurizing a fluidized bed combustor with a gas turbine greatly improves both sulfur retention and combustion efficiency. Operating the gas turbine with a high inlet temperature (e.g. 900°C) would yield a thermal efficiency about four points higher than for an atmospheric furnace, but 40 y of experience have failed to solve problems with flyash erosion and deposits. Extensive experience such as that with fluidized bed catalytic cracking units indicates that the gas turbine blade erosion and deposit problems can be handled by dropping the turbine inlet temperature below 400°C where the turbine delivers just enough power to drive the compressor. The resulting thermal efficiency is about half a point higher than for an atmospheric bed, and the capital cost of the FBC-related components is about 40% lower.
While a closed-cycle helium gas turbine might be used rather than a steam cycle, the thermal efficiency would be about four points lower and the capital cost of the FBC-related components would be roughly twice that for the corresponding steam plant.
Gas Turbine Heat Recovery Systems Predicting Fired Performance
Authors: Pasha Akber 
Published: April 2015

Heat recovery systems generate steam by extracting heat from the gas turbine exhaust. This steam is used either in a steam turbine to generate power or as a heating and drying medium in a process. Most of the time it is a combination of both. Because of the cogeneration criteria and because of the independent power and process equipment, the HRS can no longer depend on gas turbine exhaust alone to produce the needed steam. Some sort of induct auxiliary firing is employed to satisfy the steam demand. The HRS, therefore, is needed to operate satisfactorily at various ambients and loads and at fired and unfired conditions. The design of the HRS should take into consideration all of these unfired and fired conditions so that the HRS operation can be stable over the operating range.
There are numerous design parameters which affect the design and operational stability of the HRS and all these need to be reviewed at each operating condition for the design to be satisfactory. This paper presents charts and graphs which predict the probable values of these design parameters under various operating conditions. By utilizing these, the HRS user can establish the stability of the HRS performance over the operating range based on the specified design point parameters. If there is undesirable performance at a certain point, then either the operating condition or the design parameters can be changed. An HRS user can, by using these charts, be able to specify more realistic design parameters without a lengthly analysis by the HRS manufacturer which costs both money and time.
Numerical Solution of Transonic Stream Function Equation on S1 Stream Surface in Cascade
Authors: Yaonan Hua , Wenquan Wu 
Published: April 2015

A method is presented in this paper for calculating transonic flow field in turbomachinery cascades. With respect to non-orthogoanl curvilinear coordinates, the stream function equation governing fluid flow was established. Using the Artificial Compressibility Method, the discretization of the partial differential equation was carried out by use of the standard central difference formula. The set of linear algebraic equations obtained is solved by means of the Direct Matrix Method. In order to overcome the non-uniqueness of density in transonic flow in the stream function method, the velocities at grid nodes are first obtained by integrating the momentum equation and then the densities are determined from the energy equation.
Application of this method to some transonic cascade-flow with supersonic or subsonic inlet velocity shows that the solution obtained is in fair agreement with experimental data.
Particulate Flow Solutions Through Centrifugal Impeller With Two Splitters
Authors: Elfeki Salah , Tabakoff Widen 
Published: April 2015

Centrifugal impeller with splitters is one of the design techniques used in small engines. Many such engines are operating in different environmental conditions. One of which is where the atmosphere is polluted by small solid particles. Engines operating in such particulate environment are exposed to erosion and performance deterioration.
In this paper the flow field through an impeller with two different size splitters is presented. The mean streamline pattern in the meridional plane was estimated by the computer code ‘MERDIL’, and an improved panel method was used to calculate the blade-to-blade flow solution. In addition, the particle trajectories were calculated by direct integration of the particle equations of motion. Particle collisions with the blade, hub and casing surfaces were determined. The data obtained from this analysis can be applied for calculating the erosion and performance deterioration in turbomachinery with such impellers.
Gas Turbine Uses Coal Fuel With Indirect Heat Transfer via Circulating Ceramic Beads
Authors: Jahnig C. E. 
Published: April 2015

This paper defines a gas turbine power system in which the heat from coal combustion is transferred to a clean working gas by contact with a recirculated stream of hot ceramic beads. The beads are first heated by direct contact in a pressurized coal combustion zone and then the hot beads are separated, freed of coal ash and contacted directly with a pressurized gas such as air going to a gas turbine. Separate zones are used for combustion and for contact with the clean gas to be heated, and these two zones are kept separated by an intermediate column of beads at each transfer point. Similar technology is well known and used commercially in the petroleum industry, for example, in catalytic cracking of oil to make gasoline.
Hot clean gas from the operation is used to generate power in an expander, while the products from coal combustion are handled by conventional methods for environmental control. The system offers the simplicity and efficiency typical of gas turbines and avoids the large use of water typical of steam power systems. Low investment is expected, together with minimal environmental impact.
Engine Condition Monitoring at KLM Royal Dutch Airlines
Authors: Adamse Peter H. C. 
Published: April 2015

Engine Condition Monitoring (ECM) for an airline is a basic need to make its engine operation as economic as possible.
This paper describes the ECM development at KLM-Royal Dutch Airlines.
The objectives and philosophy of the systems are discussed, as well as the current and future functions and the use in the airline organisation.
AGT101 Advanced Gas Turbine Technology Update
Authors: Boyd G. L. , Kidwell J. R. , Kreiner D. M. 
Published: April 2015

The Garrett/Ford Advanced Gas Turbine Technology Development Program, designated AGT101, has made significant progress during 1985 encompassing ceramic engine and ceramic component testing. Engine testing has included full speed operation to 100,000 rpm and 1149C (2100F) turbine inlet temperature, initial baseline performance mapping and ceramic combustor start and steady state operation. Over 380 hours of test time have been accumulated on four development engines. High temperature foil bearing coatings have passed rig test and a thick precious metal foil coating selected for engine evaluation.
Ceramic structures have been successfully rig tested at 1371C (2500F) for over 27 hours. Interface compatibility testing conducted during these runs indicate RBSN-to-RBSN or SASC-to-SASC result in “sticking” — however, RBSN-to-SASC in either planar or line contact show no evidence of sticking. Ceramic combustor rig tests have demonstrated acceptable lightoffs using either a conventional ignitor or a commercially available glow plug. Operation to 1371C (2500F) combustor discharge temperatures have also been demonstrated. Ceramic turbine rotor fabrication efforts have continued at ACC and Ford. Kyocera and NGK-Locke also have been working on the rotor. Several rotors have been received and are currently undergoing final machining and qualification tests. Testing of the all-ceramic AGT101 engine is currently scheduled for late 1985.
Energy Recovery With Turbo Expanders
Authors: Cleveland Anthony 
Published: April 2015

In the oil, gas and petrochemical industry, there are many instances where energy is under-utilized, if not actually wasted.
In many cases it may be possible to recover some of this energy and obtain useful work, thereby improving plant efficiency and the economics of the operation.
The turbo expander is a simple device that can make a significant contribution to the recovery of energy in all kinds of plants.
This paper considers some ways in which turbo expanders may be used and looks in detail at an application in the gas industry where the energy lost in pressure reduction may be recovered and used to assist in reducing operating costs. The design criteria for such turbo expanders are discussed and areas for future development are proposed.
The paper concludes that there are significant gains to be made in the recovery of waste energy and that the turbo expander can play a major role in this activity.
A Model to Determine the Behaviour of a Pressure Measurement Equipment During Non-Static Operations of Gasturbine Engines
Authors: Lemmer K.-U. , Hass J. 
Published: March 2015

For some time there have existed different approaches and models by various authors to describe the behaviour of gasturbines during the transition between different operating points. A problem that has not been solved satisfactorily so far is the verification of these models with the help of exact data. Quite often one notices that the instruments do not react properly to the processs they are measuring: there is a time lag and the measured values become distorted by the measuring facility.
This paper is a contribution to the adjustments on gasturbine engines during non-static operations. A mathematical model has been developed to determine the influence of the different components on the measuring chain, which consist of a pressure measuring transducer with high natural frequency on a semiconductor base, a hose pipe and a pressure probe. This model has been verified by pressure measurements with a calibrating device. The final part is the discussion of the pressure values, which were measured on a gasturbine engine during the transition between different operating points and adjusted with the help of the mathematical model for the measuring chain.
Rainbow Field Test of Coatings for Hot Corrosion Protection of Gas Turbine Hot Section Components
Authors: Van Roode Mark , Kubarych Kenneth G. , McCarron Russell L. 
Published: March 2015

The work described in this paper was conducted under Electric Power Research Institute (EPRI) Contract RP 2465, “Rainbow Test of Advanced Coatings for Gas Turbine Blades and Vanes”.
A field test of a rainbow rotor and nozzle was carried out to establish the hot corrosion protection of various aluminide and MCrAlX (X = Y, Hf) overlay coatings on first stage blades and nozzles of a Centaur gas turbine operating in Valera, Venezuela. The blade coatings included both simple and precious metal aluminides, Electron Beam-Physical Vapor Deposition (EB-PVD) coatings and Low Pressure Plasma Spray (LPPS) coatings on Inconel-738LC, Inconel-792 and MAR-M421 substrates. The turbine nozzle vanes were coated by similar methods on FSX-414 and MAR-M509 substrates. Field testing was performed under industrial conditions where the continuous duty engine, used for power generation, ran on a liquid fuel contaminated with sodium and sulfur. The engine test was terminated after nearly 8,000 hours of operation. Visual examination and micro-structural analysis indicated that EB-PVD and LPPS overlay coatings were more effective than simple and modified aluminides for hot section hot corrosion protection. The protection of overlay coatings on nozzle airfoils was found to increase with their chromium content.
Development of the AGT101 Regenerator Seals
Authors: Fucinari C. A. , Vallance J. K. , Rahnke C. J. 
Published: March 2015

The design and development of the regenerator seals used in the AGT101 gas turbine engine are described in this paper. The all ceramic AGT101 gas turbine engine was designed for 100 hp at 5:1 pressure ratio with 2500F (1371C) turbine inlet temperature.
Six distinct phases of seal design were investigated experimentally and analytically to develop the final design. Static and dynamic test rig results obtained during the seal development program are presented. In addition, analytical techniques are described. The program objectives of reduced seal leakage, without additional diaphragm cooling, to 3.6% of total engine airflow and higher seal operating temperature resulting from the 2000F (1093C) inlet exhaust gas temperature were met.
Prediction of Gas Turbine Combustor-Liner Temperature
Authors: Najjar Yousef S. H. , Droubi Riad M. 
Published: March 2015

Broadening of fuel specifications decreases the hydrogen content and increases the aromatics and final boiling point. The cumulative effect will be an increase in soot formation hence flame radiation which affects flame tube durability.
In this work an analytical study is made where empirical formulae are developed for luminosity, radiation and convection at idle and full load conditions. These equations predict combustor liner temperature with high degree of agreement with previous experimental work.
Analysis of Windage Losses and Velocity Distribution for a Shrouded Rotating Disk
Authors: Gärtner W. 
Published: March 2015

An analysis of experimental results was carried out, establishing a direct correlation between measured velocity profiles and windage losses for a rotating disk inside a shrouded stator as typically found in turbomachinery.
The analysis gives information on the regions of the rotating and static parts, which have a dominant effect upon disk windage.
Stability of Conical and Curved Annular Diffusers for Mixed-Flow Compressors
Authors: Abir A. , Whitfield A. 
Published: March 2015

For mixed-flow compressors the downstream vaneless diffuser can be either a straight or curved annular passage. Investigations have been carried out on model diffusers six times larger than those employed in a turbocharger study, Whitfield et al (1978). This made it possible to carry out detailed internal flow measurements using a five hole yaw probe and a hot wire anemometer. The development of the flow profiles throughout the diffuser were studied with particular reference to the onset of unstable conditions. Flush mounted wall pressure transducers were also used to detect the onset of unstable flows and to measure the extent and development of the unsteady conditions.
Two curved and one straight annular diffusers have been tested in order to study their relative merits. In addition, the results obtained with a straight radial diffuser are included for comparison. It has generally been observed that the straight annular diffuser was the least stable, with the radial diffuser exhibiting the best stability characteristics. Of the two curved annular diffusers tested flow stability was improved by reducing the passage width. In both cases, however, the curved diffuser proved to be clearly superior to the simpler straight design.
Combined Cycle Repowering Two Concepts at Virginia Power
Authors: Rives J. D. , Letarte J. R. , Catina J. L. 
Published: March 2015

A study was undertaken to determine the engineering and economic feasibility of repowering several conventional pulverized coal and oil fired units with combustion turbines.
Both feedwater repowering and hot windbox repowering were examined. Performance was evaluated using PEPSE.
The results of the most promising units are presented in detail.
The duration of the study was six months and the project cost approximately $75,000.