bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery
Authors: Py G. , Ramonatxo C. , Sirvent P. , Sanchez A. M. J. , Philippe A. G. , Douillard A. , Galbès O. , Lionne C. , Bonnieu A. , Chopard A. , Cazorla O. , Lacampagne A. , Candau R. B. 
Published: February 2015

Key points
Clenbuterol is an adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a shift towards faster muscle fibres, when administered chronically at high doses.
However, when normalized to the muscle surface area, the increase in muscle force is no longer increased and even depressed.
We show that muscle contraction and relaxation force kinetics were significantly reduced particularly in fast contracting muscles.
We show that action potential‐elicited Ca2+ transients were depressed in the fast contracting muscle.
Our data show that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects.
AbstractClenbuterol is a β2‐adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow‐to‐fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium‐handling ability. Forty‐three 6‐week‐old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg−1 day−1) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol‐treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential‐elicited Ca2+ transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol‐treated animals demonstrated decreased amplitude after 14 days (−19%, P < 0.01) and 21 days (−25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects.
The Prediction of the Tip Clearance Vortex Circulation and its Induced Flow Field in Axial Flow Machines
Authors: Nikolos I. K. , Douvikas D. I. , Papailiou K. D. 
Published: February 2015

A model for the prediction of the leakage vortex circulation was developed, based on the assumption that the leakage jet flow enters as a whole the vortex core, increasing its radius and its moment of momentum in the direction of the vortex axis. Using the assumption that the leakage vortex has a solid body rotation, an expression was derived for the vortex circulation, which demonstrates that this circulation is proportional to the square root of the corresponding tip clearance height. This theoretical result is supported by the available experimental data for both compressors and turbines. A simple model was developed, which demonstrates the ability of the proposed theory to calculate the leakage vortex circulation, provided that the vortex trace is known.
A method for predicting the tip clearance effects in the flow field inside and downstream the blade passage, compatible with a meridional flow calculation procedure, has been developed by the authors. The method uses incompressible considerations and accounts for the calculation of the circumferentially mean deficit radial profiles of the various flow quantities. In the calculation procedure the tip clearance flow effects are considered as a modification to the basic flow, existing in the absence of tip clearance. The complete calculation procedure was used in order to calculate the leakage vortex circulation and the induced velocity field in various axial flow cases, with satisfactory results.
SiC High Temperature Electronics for Next Generation Aircraft Controls Systems
Authors: Perkins John F. , Hopkins Richard H. , Brandt Charles D. , Agarwal Anant K. , Seshadri Suresh , Siergiej Richard R. 
Published: February 2015

Several organizations, including Westinghouse, CREE, and ATM, as well as researchers in Japan and Europe, are working to develop SiC power devices for reliable, high power and high temperature environments in military, industrial, utility, and automotive applications. Other organizations, such as NASA Lewis and several universities, are also doing important basic work on basic SiC technology development. It has been recognized for two decades that the superior properties of SiC lead to range of devices with higher power, greater temperature tolerance, and significantly more radiation hardness than silicon or GaAs. This combination of superior thermal and electrical properties results in SiC devices that can operate at up to ten times the power density of Si devices for a given volume.
Recent research has focused on the development of vertical metal oxide semiconductor field effect transistor (VMOSFET) power device technology, and complementary high speed, temperature-tolerant rectifier-diodes for power applications. We are also evaluating applications for field control thyristors (FCT) and MOS turn-off thyristors (MTO). The technical issues to be resolved for these devices are also common to other power device structures. The present paper reviews the relative benefits of various power devices structures, with emphasis on how the special properties of SiC enhance the desirability of specific device configurations as compared to the Si-based versions of these devices. Progress in SiC material quality and recent power device research will be reviewed, and the potential for SiC-based devices to operate at much higher temperatures than Si-based devices, or with enhanced reliability at higher temperatures will be stressed. We have already demonstrated 1000V breakdown, current densities of 1 kA/cm2, and measurements up to 400°C in small diodes. The extension of this work will enable the implementation of highly distributed aircraft power control systems, as well as actuator and signal conditioning electronics for next generation engine sensors, by permitting electronic circuits, sensors and smart actuators to be mounted on or at the engine.
A New Approach for a Low-Cooled Ceramic Nozzle Vane
Authors: Gutmann C. , Schulz A. , Wittig S. 
Published: February 2015

At the Institute for Thermal Turbomachinery, University of Karlsruhe (ITS) a new methodology for designing thermally loaded ceramic components based on numerical analyses of the thermal and structural behaviour is developed. Major issues are an effective optimization of the geometry and an assessment of the load.
To reduce thermally induced stresses in shell structures exposed to hot gas flow a precise description of the major influencing parameters is required. Based on these relations a thermal optimization of the component is possible. Moreover, the compensation of thermal strains and the adjustment of local stiffnesses for reducing the tensile stresses and the failure probability has to be considered.
In designing a first stage vane of a stationary gas turbine the proposed guidelines are verified. The advantages of a systematic approach are demonstrated. The multi-purpose numerical procedures using the guidelines allow an adjustment of the shape to thermally and mechanically induced loads and offer new possibilities to meet the specific demands of ceramic materials.
Biomass-Fired Atmospheric Gas Turbine Plant
Authors: Fesharaki M. , Moser S. , Halozan H. , Jericha H. 
Published: February 2015

Considering the expected climate change biomass is one of the promising energy sources for the future; however, burning and only producing low temperature heat means wasting exergy. To utilize this renewable fuel highly efficient cogeneration plants are required. Existing small and medium sized power generation systems using gas turbines have either complicated flow sheets or problems with charging pressurized combustion chambers, which are not yet solved.
This project deals with the investigation and the development of an atmospheric biomass combustion chamber combined with an inverted gas turbine cycle followed by a steam cycle. The system consists of a combustor with a wood grate firing working at atmospheric pressure. A gas turbine expands the hot particle loaded exhaust gas with a temperature of about 800 to 1000°C from atmospheric pressure down to a pressure of about 0.35 bar. The exhaust gas of the turbine is used for operating a single-pressure steam generator, the steam is mainly utilized for power generation in a steam turbine, a part stream is used to control the gas turbine inlet temperature depending on the moisture content of the fuel. The gas outlet temperature of the steam generator is about 186°C (Fig. 1, p6) at a pressure of 0.3 bar, one part is used for preheating the air required for combustion, the other part is cooled down by water injection, whereby ashes and particles are separated. The cleaned gas is compressed to atmospheric pressure again (Moser, 1995).
Such a system can achieve an efficiency of up to 40 % in the MW electricity range using components, which are available on the market, and at the same time it demonstrates the possibility of highly efficient biomass utilization.
Status of the Development of the CGT301, a 300 KW Class Ceramic Gas Turbine
Authors: Mikami Takao , Tanaka Shinya , Tatsuzawa Masashi , Sakida Takeshi 
Published: February 2015

The CGT301 ceramic gas turbine is being developed under a contract from NEDO as a part of the New Sunshine Program of MTTI to improve the performance of gas turbines for cogeneration through the replacement of hot section components with ceramic parts.
The project is conducted in three phases. The project currently in Phase 2 focuses on the development of the “primary type” ceramic gas turbine (turbine inlet temperature: 1,200°C).
CGT301 is a recuperated, single-shaft, ceramic gas turbine. The turbine is a two-stage axial flow type. The major effort has been on the development of the turbine which consists of metallic disks and inserted ceramic blades (“hybrid rotor”).
Prior to engine tests, component tests were performed on the hybrid rotor to prove the validity of the design concepts and their mechanical integrity.
The engine equipped with all ceramic components except the second stage turbine blades was tested and evaluated. The engine was operated successfully for a total of 23 hours without failure at the rated engine speed of 56,000 rpm with the turbine inlet temperature of 1,200 °C.
Further, the engine equipped with all ceramic components was successfully tested for one hour under the same conditions.
Engine testing of the “primary type” ceramic gas turbine is continuing to improve the performance and the reliability of the system for the purpose of moving forward to the development of the “pilot” ceramic gas turbine (turbine inlet temperature: 1,350 °C) as the final target of this project.
This paper summarizes the progress in the development of the CGT301 with the emphasis on the test results of the hybrid rotor.
A Methodology for Establishing Optimal Part-Load Operation of Industrial Gas Turbines
Authors: Bozza Fabio , Tuccillo Raffaele 
Published: February 2015

The authors present the application of a method for gas turbine analysis, that they have recently introduced, based upon the selection of rotating components and on the study of off-design behaviour. The paper deals with an aero-derivative gas turbine, whose operating field is evaluated by an advanced cycle calculation which takes into account the fluid-dynamic and mechanical matching of the turbomachines.
Different regulation systems are considered, like variable-geometry compressor and turbine vanes, whose effect is combined with the variations in rotational speed of the gas generator device.
The simulation model allows definition of a performance map of the gas turbine, not only in terms of mechanical output and efficiency but also of pollutant emissions, as a result of the prediction of thermal NO formation inside the combustor.
The method leads to the establishment of an optimal control and regulation strategy with respect to a prescribed objective, i.e., either for maximum in energy saving or for the best compromise between performance and emission levels. Cases are examined with reference to both mechanical energy production and combined heat and power generation.
Biomass Gasification Hot Gas Filter Testing Results
Authors: Wiant Benjamin C. , Bachovchin Dennis M. , Onischak Michael , Carty Ronald H. , Ratcliff Matthew 
Published: February 2015

Westinghouse Electric Corporation, under contract to the US Department of Energy’s National Renewable Energy Laboratory, has been conducting hot gas cleanup system testing compatible with a pressurized fluidized bed gasifier and the operation of a gas turbine. The testing is in support of the US Department of Energy’s Binmass Power Program, and specifically, the Biomass Gasification Facility Demonstration in Paia, Hawaii.
The hot gas cleanup testing was conducted at the Institute of Gas Technology’s research facilities in Chicago, Illinois, using the RENUGAS® 9.1 metric ton (10 ton) per day process development unit. The initial testing began in September 1994 and concluded February 1995. Based on the results of this testing, the hot gas cleanup system’s operation is being optimized for longer duration testing to be conducted at the Biomass Gasification Facility in Hawaii.
Initial test results show that hot gas filtration of bagasse flyash/char, as well as tar and oils reduction, at gasifier operating conditions can be successfully accomplished. The results of these initial tests are summarized in this paper.
Computational Prediction of Heat Transfer to Gas Turbine Nozzle Guide Vanes With Roughened Surfaces
Authors: Guo S. M. , Jones T. V. , Lock G. D. , Dancer S. N. 
Published: February 2015

The local Mach number and heat transfer coefficient over the aerofoil surfaces and endwalls of a transonic gas turbine nozzle guide vane have been calculated. The computations were performed by solving the time averaged Navier-Stokes equations using a fully three-dimensional computational code (CFDS) which is well established at Rolls-Royce.
A model to predict the effects of roughness has been incorporated into CFDS and heat transfer levels have been calculated for both hydraulically smooth and transitionally rough surfaces. The roughness influences the calculations in two ways; firstly the mixing length at a certain height above the surface is increased; secondly the wall function used to reconcile the wall condition with the first grid point above the wall is also altered. The first involves a relatively straightforward shift of the origin in the van Driest damping function description, the second requires an integration of the momentum equation across the wall layer. A similar treatment applies to the energy equation.
The calculations are compared with experimental contours of heat transfer coefficient obtained using both thin film gauges and the transient liquid crystal technique. Measurements were performed using both hydraulically smooth and roughened surfaces, and at engine-representative Mach and Reynolds numbers. The heat transfer results are discussed and interpreted in terms of surface-shear flow visualisation using oil and dye techniques.
Sizing of a Gas Turbine for Repowering of Cogeneration Power Plant Ljubljana by Mathematical Optimisation
Authors: Tomšič Mihael Gabriel , Perović Olgica 
Published: February 2015

The paper deals with optimal sizing of a gas turbine for repowering of cogeneration power plant Ljubljana considering possible plant operational strategy with respect to variations of electric and heat loads and energy costs. CHP plant is a main source for the Ljubljana town district heating system. Existing plant consists of two condensing steam turbines with steam extraction, back pressure turbine with steam extraction, auxiliary steam and hot water boilers for peak heat load production. This system delivers up to 111 MW into the power grid and up to 348 MW of heat. Repowering with gas turbine generator set with additionally fired heat recovery boiler is considered. For uncoupling heat and power generation a heat storage tank is assumed.
For sizing of new equipment and plant operational strategy a model based on mixed-integer linear programming was developed. Zero - one integer variables are adopted to indicate the on/off status of operation, continuous variables to indicate the operational level of each constituent equipment and an optimal solution is derived by branch and bound method.
Two prospective sizes of TG sets were tested for range of assumptions regarding power purchase tariff schedules. Different optimal operation policies resulted. The study provides background for contract negotiation and for investment decisions.
Optimisation of Bypass Fan Outlet Guide Vanes
Authors: Parry A. B. 
Published: February 2015

In this paper we describe an approach for combined intake-fan-OGV-pylon interactions that can be used to optimise the OGV design. The mean flow through the fan and OGVs, which is taken to be locally two-dimensional, is prescribed for a datum configuration, and the intake distortion and pylon potential field are fed in, from upstream and downstream respectively, as small incident perturbations to a coupled fan-OGV actuator disk system. In order to optimise the OGVs we suppose that the vanes are recambered in blocks, using only a limited number of vane types. The extent of each block, and the degree of over or undercambering in each block, are used as variables within a standard multi-variable optimisation package.
Following validation of the approach, results are presented for a number of cases which show, in particular, the importance of the back effect of the fan on the perturbation field at the OGV leading edge, and the relative benefits obtained by increasing the number of vane types.
The Ammonia and Diazo Technique With CO2-Calibration for Highly Resolving and Accurate Measurement of Adiabatic Film Cooling Effectiveness With Application to a Row of Holes
Authors: Haslinger W. , Hennecke D. K. 
Published: February 2015

The ammonia and diazo technique with CO2-calibration for highly resolving measurement of adiabatic film cooling effectiveness distribution has been developed and improved with respect to high accuracy.
Both parts of the technique are based on the analogy between heat and mass transfer. In the ammonia and diazo part a mixture of ammonia and air is injected through the film cooling holes. Downstream of the injection a diazo film is mounted on the experimental surface. Depending on the local ammonia concentrations along the wall the diazo film turns blue. In the CO2-calibration part carbon dioxide is used as a tracer gas. Gas samples are sucked off and analyzed, thus giving the adiabatic film cooling effectiveness at certain locations on the surface. Relating the effectiveness values to the color intensities of the diazo film at the corresponding locations a calibration curve is derived.
This calibration can be applied to the whole color distribution of the diazo film resulting in a highly resolved distribution of the adiabatic film cooling effectiveness. The scattering of the measured values along the calibration curve directly indicates the quality of the measurement.
The ammonia and diazo technique with CO2-calibration has been applied to injection through a row of holes (α = 35°, p/D = 3) in the flat wall of a wind tnnnel for different blowing rates. The results show a very good suitability of this technique, especially, but not only, if the region around the film cooling holes is of special interest.
Numerical Study of Bicomponent Droplet Vaporization in a High Pressure Environment
Authors: Stengele J. , Bauer H.-J. , Wittig S. 
Published: February 2015

The understanding of multicomponent droplet evaporation in a high pressure and high temperature gas is of great importance for the design of modern gas turbine combustors, since the different volatilities of the droplet components affect strongly the vapor concentration and, therefore, the ignition and combustion process in the gas phase. Plenty of experimental and numerical research is already done to understand the droplet evaporation process. Until now, most numerical studies were carried out for single component droplets, but there is still lack of knowledge concerning evaporation of multicomponent droplets under supercritical pressures. In the study presented, the Diffusion Limit Model is applied to predict bicomponent droplet vaporization. The calculations are carried out for a stagnant droplet consisting of heptane and dodecane evaporating in a stagnant high pressure and high temperature nitrogen environment. Different temperature and pressure levels are analyzed in order to characterize their influence on the vaporization behavior. The model employed is fully transient in the liquid and the gas phase. It accounts for real gas effects, ambient gas solubility in the liquid phase, high pressure phase equilibrium and variable properties in the droplet and surrounding gas.
It is found that for high gas temperatures (T = 2000 K) the evaporation time of the bicomponent droplet decreases with higher pressures, whereas for moderate gas temperatures (T = 800 K) the lifetime of the droplet first increases and then decreases when elevating the pressure. This is comparable to numerical results conducted with single component droplets. Generally, the droplet temperature increases with higher pressures reaching finally the critical mixture temperature of the fuel components. The numerical study shows also that the same tendencies of vapor concentration at the droplet surface and vapor mass flow are observed for different pressures. Additionally, there is almost no influence of the ambient pressure on fuel composition inside the droplet during the evaporation process.
An Unsteady Velocity Formulation for the Edge of the Near-Wall Region
Authors: Wilson Dennis E. , Hanford Anthony J. 
Published: February 2015

A phenomenological model is presented that relates freestream turbulence to the augmentation of stagnation-point surface flux quantities. The model requires the turbulence intensity, the longitudinal scale of the turbulence, and the energy spectra as inputs for the unsteady velocity at the edge of the near-wall viscous region. The form of the edge velocity contains both pulsations of the incoming flow and oscillations of the streamline.
Incompressible results using a single fluctuating component are presented within the stagnation region of a two-dimensional cylinder. The time-averaged Froessling number is determined from the computations. These predictions are compared to existing incompressible experimental data. Additionally, the variations in the surface flux quantities with the longitudinal scale of the incoming freestream turbulence, the Reynolds number, and the freestream turbulence intensity are considered.