bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parameterization of High Solar Share Gas Turbine Systems
Authors: Heide Stephan , Felsmann Christian , Gampe Uwe , Boje Sven , Gericke Bernd , Freimark Manfred , Langnickel Ulrich , Buck Reiner , Giuliano Stefano 
Published: December 2013

Existing solar thermal power plants are based on steam turbine cycles. While their process temperature is limited, solar gas turbine (GT) systems provide the opportunity to utilize solar heat at a much higher temperature. Therefore there is potential to improve the efficiency of future solar thermal power plants.
Solar based heat input to substitute fuel requires specific GT features. Currently the portfolio of available GTs with these features is restricted. Only small capacity research plants are in service or in planning. Process layout and technology studies for high solar share GT systems have been carried out and have already been reported by the authors. While these investigations are based on a commercial 10MW class GT, this paper addresses the parameterization of high solar share GT systems and is not restricted to any type of commercial GT.
Three configurations of solar hybrid GT cycles are analyzed. Besides recuperated and simple GT with bottoming Organic Rankine Cycle (ORC), a conventional combined cycle is considered.
The study addresses the GT parameterization. Therefore parametric process models are used for simulation. Maximum electrical efficiency and associated optimum compressor pressure ratio πC are derived at design conditions. The pressure losses of the additional solar components of solar hybrid GTs have a different adversely effect on the investigated systems. Further aspects like high ambient temperature, availability of water and influence of compressor pressure level on component design are discussed as well.
The present study is part of the R&D project Hybrid High Solar Share Gas Turbine Systems (HYGATE) which is funded by the German Ministry for the Environment, Nature and Nuclear Safety and the Ministry of Economics and Technology.
Contribution to Free and Forced Vibration Analysis of an Intentionally Mistuned Blisk
Authors: Schoenenborn Harald , Junge Michael , Retze Ulrich 
Published: December 2013

Most of the experimental mistuning studies are performed using a blisk with random mistuning only. Intentional mistuning is often investigated analytically with respect to aeroelasticity, as it is well known that intentional mistuning reduces the flutter risk due to less interaction between the blades.
In this paper, an intentionally mistuned test blisk is investigated both analytically and experimentally with respect to free and forced vibrations. First, free vibrations are studied and aliasing effects for the intentionally mistuned blisk are analyzed in comparison with a tuned blisk. A comparison between the experimentally determined dominant nodal diameters and the computed ones shows good agreement.
Then, the blisk is experimentally excited by a travelling wave for various engine orders. Similar investigations are performed with a FEM model of the blisk and a reduced-order code. The amplification factor for some modes and several blisks is compared. The influence of the disc onto the blade mode shapes is studied for the tuned and mistuned case without and with aerodynamic coupling effects.
Cyclic spacing of vanes is a concept to reduce the vibration level of downstream rotor blades by distributing the excitation onto more engine orders while reducing the overall excitation level. In this paper it is shown for blisks with and without intentional mistuning that care should be taken in applying this concept in the vicinity of veering regions, because the amplification factor in a veering region may become much higher than compared to other nodal diameters.
Supercritical Carbon Dioxide Power Cycle Configurations for Use in Concentrating Solar Power Systems
Authors: Turchi Craig S. , Ma Zhiwen , Dyreby John 
Published: December 2013

Concentrating Solar Power (CSP) plants utilize oil, molten salt or steam as the heat transfer fluid (HTF) to transfer solar energy to the power block. These fluids have properties that limit plant performance; for example, the synthetic oil and molten salt have upper temperature limits of approximately 390°C and 565°C, respectively. While direct steam generation has been tested, it requires complex controls and has limited options for integration of thermal energy storage. Use of carbon dioxide as the HTF and power cycle working fluid offers the potential to increase thermal cycle efficiency while maintaining simplicity of operation and thermal storage options.
Supercritical CO2 (s-CO2) operated in a closed-loop recompression Brayton cycle offers the potential of higher cycle efficiency versus superheated or supercritical steam cycles at temperatures relevant for CSP applications. Brayton-cycle systems using s-CO2 have smaller weight and volume, lower thermal mass, and less complex power blocks versus Rankine cycles due to the higher density of the fluid and simpler cycle design. Many s-CO2 Brayton power cycle configurations have been proposed and studied for nuclear applications; the most promising candidates include recompression, precompression, and partial cooling cycles.
Three factors are important for incorporating s-CO2 into CSP plants: superior performance vs. steam Rankine cycles, ability to integrate thermal energy storage, and dry-cooling. This paper will present air-cooled s-CO2 cycle configurations specifically selected for a CSP application. The systems will consider 10-MW power blocks that are tower-mounted with an s-CO2 HTF and 100-MW, ground-mounted s-CO2 power blocks designed to receive molten salt HTF from a power tower.
Modelling Rain Drop Impact of Offshore Wind Turbine Blades
Authors: Keegan M. H. , Nash D. H. , Stack M. M. 
Published: December 2013

The effects of rain and hail erosion and impact damage on the leading edge of offshore wind turbine blades have been investigated.
A literature review was conducted to establish the effects of exposure to these conditions and also to investigate the liquid impact phenomena and their implications for leading edge materials. The role of Explicit Dynamics software modelling in simulating impact events was then also established.
Initial rain impact modelling is then discussed with the results showing good agreement with theoretical predictions both numerically and with respect to the temporal and spatial development of the impact event. Future development of the rain model and a proposed hail model are then detailed.
Planned rain impact and erosion testing work is addressed which will be used to validate, inform and compliment the ongoing modelling efforts.
Vortex Generators for Wind Turbine Blades: A Combined Wind Tunnel and Wind Turbine Parametric Study
Authors: Mueller-Vahl Hanns , Pechlivanoglou Georgios , Nayeri C. N. , Paschereit C. O. 
Published: December 2013

Vortex generators (VGs) are passive flow control devices commonly employed to prevent flow separation on wind turbine blades. They mitigate the damaging fatigue loads resulting from stall while increasing lift and consequently lead to rotor torque increase. This work summarizes a research project aimed at optimizing the sectional as well as the full rotor-blade aerodynamics using VGs.
The effects of chordwise position, spanwise spacing and VG size were studied with force balance measurements of a 2D wing section. Reducing the distance between adjacent VGs produced large increases in the static stall angle and maximum lift, but also resulted in a significant increase in drag as well as sharp lift excursions at angles exceeding the static stall angle. The optimal chordwise position of the vortex generators was found to be in the range of x/c = 15%–20%, where a comparatively low parasitic drag and a smooth post-stall lift curve were achieved. Particle Image Velocimetry measurements were conducted at various chordwise positions to provide insight into the interaction between adjacent streamwise vortices.
The experimental aerodynamic performance curves of the optimal VG configuration were used to project their effect on wind turbine blade aerodynamics. Three different rotorblades were designed and several stall and pitch regulated wind turbine models were simulated by means of a Blade Element Momentum (BEM) code (QBlade) developed by Smart Blade GmbH. The performance of the rotorblades with and without VGs was simulated in order to assess their effect on the aerodynamic performance and loads. Finally, previously measured steady state performance curves under high-roughness conditions were used to simulate the detrimental effect of surface roughness on the performance of the aforementioned rotorblades. This allows for an estimate of the potential of the VGs to be employed as retrofit elements for performance recovery of blades with a contaminated surface.
Through Flow Matching of Power Turbine for a Turbo-Compounded Diesel Engine
Authors: Zhao Rongchao , Zhuge Weilin , Zhang Yangjun , Yin Yong , Li Zhigang , Wang Jiawei 
Published: December 2013

Turbo-compounding (TC) is a possible solution to make transportation more ecological. Matching the engine with an appropriate power turbine is the key for the turbo-compounded engine performance optimization. Conventionally, the matching work is based on a turbine map. The influences of the turbine geometry parameters on the engine performance are taken into account.
A new matching method based on the turbine through flow model is presented in this paper. The influences of geometry parameters of the power turbine on the diesel engine performance are investigated. The research focuses on the effects of inlet blade radius and height, exit blade angle and tip radius of the power turbine on the engine BSFC and torque. Results show that the outlet blade angle and tip radius have stronger impacts on BSFC and torque of the engine than the inlet blade radius and height. Further studies show that the engine cycle and air mass flow rate are more sensitive to the outlet blade tip radius and angle than the inlet blade radius and height.
Optimized Steam Turbine Governor Controlling Single or Multiple Grid Faults
Authors: Bennauer Martin , Kreischer Christian , Rosendahl Jens , Werthes Heribert 
Published: December 2013

This paper uses simulation results to figure out how SIEMENS handles a single grid fault of a three–phase short circuit close to the power plant and a multiple grid fault of a load rejection due to a three–phase short circuit close to the power plant.
The correct response of the steam turbine governor to the single and the multiple grid fault can increase power plant availability, prevent steam turbine trips and reduce overspeed. Therefore the power supply to the electrical grid can still be maintained, and in case of a de-stabilized electrical grid a black-out could be prevented.
If the steam turbine trips caused by the single or the multiple grid fault the steam turbine runs down and has to be restarted. This could take several hours as worst case. During this time the power plant is not available to support and stabilize the electrical grid.
If the steam turbine governor is able to handle the single grid fault, the power plant is still connected to the grid. This will not further stress the de-stabilized electrical grid.
If the steam turbine governor is able to handle the multiple grid fault, the house load of the power plant will still be provided by the steam turbine. The operator could re-synchronize the power plant with the de-stabilized electrical grid as fast as possible.
In both cases for the single and the multiple grid fault the power plant remains available by the optimized steam turbine governor.
Measured Performance of Two-Stage Centrifugal Compressor Under Wet Gas Conditions
Authors: Bertoneri Matteo , Duni Simone , Ransom David , Podestà Luigi , Camatti Massimo , Bigi Manuele , Wilcox Melissa 
Published: December 2013

The oil and gas industry is moving forward to access the most remote gas reserves and enhance the exploitation of the existing installation or postponing their tail-end. To achieve these accomplishments several technology challenges are being unveiled. In topside upstream application both offshore and onshore, one important technology issue is the capability to compress gas with a significant amount of liquids and it assumes a special interest in case of the facilities revamping. Nevertheless is in the subsea environment where this technology issue becomes really challenging. In order to properly design and size a compressor/motor system for subsea wet gas compression, one must be able to adequately predict the compressor performance with mixed phase flow.
This paper presents the results from an experimental test program which investigated the performance of a centrifugal compressor at various wet gas conditions with elevated suction pressure. Performance tests are completed on a two stage centrifugal compressor with a mixture of air and water at suction pressures of 20 bar (300 psi). The compressor is subjected to flow with liquid volume fractions ranging from 0 to 5% along three speedlines.
The performance measurements are made in accordance with ASME PTC-10 specifications with an additional torque measurement on the shaft between the compressor and gearbox. At each test condition, once the liquid is injected in the air flow, an increase in pressure ratio occurs. This testifies the compressor is still able to work in presence of water. However, increasing the amount of liquid injected a decreased polytropic head together with an increased absorbed actual power by the compressor cause a deterioration of its efficiency. Moreover when liquid is introduced into the flow, the discharge temperature of the compressor reduces significantly.
The performance results and trends mentioned above are reviewed in the detail in this paper.
Dynamic Pipeline System Simulation of Multi-Stage Compressor Trains
Authors: Garcia-Hernandez Augusto , Tavares Theodore Sean , Wilcox Melissa 
Published: December 2013

An oil and gas company was facing process and mechanical related problems on the multiple-stage compressor trains at two important booster installations. The frequency of these problems has increased lately, and this has led to frequent trips and shut downs. These interruptions affect the operation of the plant leading to a loss in production and consequences of lost revenue for the company. The two platforms each contain one compressor train comprising a four-stage compressor with a gas turbine driver. Each train is fitted with an integrated turbine compressor control panel.
Thus, a detailed dynamic pipeline system simulation of the subject compressor trains was performed in order to provide a series of recommendations that would improve the safe operation and increase the reliability of the compression systems. The analysis included a review of the existing compression systems including all the equipment and hardware related with the compression anti-surge system. In addition, a site visit was performed to review and understand the existing anti-sure control system at each facility. A detailed dynamic model of the multi-stage compression system was built for each train. These models included compressor performance maps, gas compositions for each stage and train, piping yard, recycle, isolation, check and blowdown valves, scrubbers, separators, and coolers.
Several simulation cases were conducted for both the platform systems. These cases evaluated the effect of the delay and travel times of the existing anti-surge valves, delay the coast down action, failure of the non-return valves (NRVs), action of a blowdown valve on the emergency shutdown (ESD) sequences, recycle valve bypasses, check valve arrays, and process upset conditions. In addition, parametric studies were conducted for each of the most important parameters of the system to quantify their effect of any possible modification.
The results of this analysis provide recommendations to solve some of the existing issues while understanding more of the dynamics of the system. It was found that any propose recommendation or change in the sequence or timing of one stage will affect the surrounding stages since they are not only connected through the piping as they are driven by the same gas turbine shaft. Therefore, a very comprehensive analysis was conducted for each train to provide recommendations that would be feasible for implementation while reducing the constant risk of mechanical failure and surge events. Thus, results of the analysis and some of the recommendations obtained are presented in this paper.
Summary of Linezolid Activity and Resistance Mechanisms Detected during the 2012 LEADER Surveillance Program for the United States
Authors: Mendes Rodrigo E. , Flamm Robert K. , Hogan Patricia A. , Ross James E. , Jones Ronald N. 
Published: December 2013

ABSTRACT

This study summarizes the linezolid susceptibility testing results for 7,429 Gram-positive pathogens from 60 U.S. sites collected during the 2012 sampling year for the LEADER Program. Linezolid showed potent activity when tested against 2,980
Staphylococcus aureus
isolates, inhibiting all but 3 at ≤2 μg/ml. Similarly, linezolid showed coverage against 99.5% of enterococci, as well as for all streptococci tested. These results confirm a long record of linezolid activity against U.S. Gram-positive isolates since regulatory approval in 2000.
In Vitro
Activity of Fosfomycin against Escherichia coli Isolated from Patients with Urinary Tract Infections in Canada as Part of the CANWARD Surveillance Study
Authors: Karlowsky James A. , Denisuik Andrew J. , Lagacé-Wiens Philippe R. S. , Adam Heather J. , Baxter Melanie R. , Hoban Daryl J. , Zhanel George G. 
Published: December 2013

ABSTRACT

We tested 868 urinary isolates of
Escherichia coli
collected from 2010 to 2013 as part of the Canadian national surveillance study CANWARD against fosfomycin by using the Clinical and Laboratory Standards Institute (CLSI) agar dilution method with MIC interpretation in accordance with the CLSI M100-S23 (2013) criteria. The concentrations of fosfomycin inhibiting 50 and 90% of the isolates were ≤1 and 4 μg/ml; 99.4% of the isolates were susceptible to fosfomycin.
Klebsiella pneumoniae Induces an Inflammatory Response in an
In Vitro
Model of Blood-Retinal Barrier
Authors: Motta C. , Salmeri M. , Anfuso C. D. , Amodeo A. , Scalia M. , Toscano M. A. , Giurdanella G. , Alberghina M. , Lupo G. 
Published: December 2013

ABSTRACT

Klebsiella pneumoniae
has become an important pathogen in recent years. Although most cases of
K. pneumoniae
endogenous endophthalmitis occur via hematogenous spread, it is not yet clear which microbial and host factors are responsible for the ability of
K. pneumoniae
to cross the blood-retinal barrier (BRB). In the present study, we show that in an
in vitro
model of BRB based on coculturing primary bovine retinal endothelial cells (BREC) and primary bovine retinal pericytes (BRPC),
K. pneumoniae
infection determines changes of transendothelial electrical resistance (TEER) and permeability to sodium fluorescein. In the coculture model, bacteria are able to stimulate the enzyme activities of endothelial cytosolic and Ca
2+
-independent phospholipase A
2
s (cPLA
2
and iPLA
2
). These results were confirmed by the incremental expression of cPLA
2
, iPLA
2
, cyclo-oxygenase-1 (COX1), and COX2 in BREC, as well as by cPLA
2
phosphorylation. In supernatants of
K. pneumoniae
-stimulated cocultures, increases in prostaglandin E
2
(PGE
2
), interleukin-6 (IL-6), IL-8, and vascular endothelial growth factor (VEGF) production were found. Incubation with
K. pneumoniae
in the presence of arachidonoyl trifluoromethyl ketone (AACOCF
3
) or bromoenol lactone (BEL) caused decreased PGE
2
and VEGF release. Scanning electron microscopy and transmission electron microscopy images of BREC and BRPC showed adhesion of
K. pneumoniae
to the cells, but no invasion occurred.
K. pneumoniae
infection also produced reductions in pericyte numbers; transfection of BREC cocultured with BRPC and of human retinal endothelial cells (HREC) cocultured with human retinal pericytes (HRPC) with small interfering RNAs (siRNAs) targeted to cPLA
2
and iPLA
2
restored the pericyte numbers and the TEER and permeability values. Our results show the proinflammatory effect of
K. pneumoniae
on BREC, suggest a possible mechanism by which BREC and BRPC react to the
K. pneumoniae
infection, and may provide physicians and patients with new ways of fighting blinding diseases.
What happens to deformed rocks after deformation? A refined model for recovery based on numerical simulations
Authors: Borthwick V. E. , Piazolo S. , Evans L. , Griera A. , Bons P. D. 
Published: December 2013

Abstract

Deformation, in large parts of the middle crust, results in strained rocks consisting of grains with variable dislocation densities and microstructures which are characterized by gradual distortion and subgrain structures. Post-deformation residence of these rocks at elevated temperatures results in microstructural adjustments through static recovery and recrystallization. Here, we employ a numerical technique to simulate intragrain recovery at temperatures at or below the deformation temperature. The simulation is based on minimization of the stored energy, related to misorientation through local rotation of physical material points relative to their immediate environment. Three temperature- and/or deformation-geometry-dependent parameters were systematically varied: (1) deformation-induced dislocation types, (2) dislocation mobility and (3) size of dislocation interaction volume. Comparison with previously published
in situ
experiments shows consistency of numerical and experimental results. They show temperature- and dislocation-type-dependent small-scale fluctuations in subgrain-boundary misorientations and orientation variation within subgrains. These can be explained by the combined effect of increase in dislocation interaction volume and activation of climb. Our work shows microstructure can be significantly modified even if the post-deformational temperature is at or below the deformation temperature: a scenario relevant for most deformed rocks.
Improving the fault resilience of an H.264 decoder using static analysis methods
Authors: Schmoll Florian , Heinig Andreas , Marwedel Peter , Engel Michael 
Published: December 2013

Fault tolerance rapidly evolves into one of the most significant design objectives for embedded systems due to reduced semiconductor structures and supply voltages. However, resource-constrained systems cannot afford traditional error correction for overhead and cost reasons. New methods are required to sustain acceptable service quality in case of errors while avoiding crashes.
We present a flexible fault-tolerance approach that is able to select correction actions depending on error semantics using application annotations and static analysis approaches. We verify the validity of our approach by analyzing the vulnerability and improving the reliability of an H.264 decoder using flexible error handling.