bluuebunny/crossref_metadata_2025_split huggingface dataset:
Smart Polygeneration Grid: A New Experimental Facility
Authors: Ferrari Mario L. , Pascenti Matteo , Traverso Alberto , Rivarolo Massimo 
Published: July 2013

This paper presents the development of a new experimental facility for analysis and optimization activities on smart polygeneration grids. The test rig is being designed and built in the framework of the European project “Energy-Hub for residential and commercial districts and transport” (E-HUB), which targets optimal energy management of residential and commercial districts.
The experimental rig, named “Energy aNd Efficiency Research Demonstration District” (E-NERDD), is located inside the University campus in Savona, and is based on four different prime movers able to produce both electrical and thermal energy: a 100 kWe micro gas turbine, a 20 kWe internal combustion engine, a 3 kWe Stirling engine, and a 450 kWe fuel cell/gas turbine hybrid system emulator based on the coupling of a micro gas turbine with a modular vessel. While the electrical side is based on the connection with the campus grid (further developments are planned for a local electrical grid including storage units), thermal energy is managed through a dual ring-based water distribution system. The facility is also equipped with thermal storage tanks and fan cooler units to study and optimize different thermal management algorithms generating different thermal load demands. The facility also includes an absorption chiller for cold water generation. As a result, trigeneration operation is possible in a physically simulated urban district. Moreover, the rig is equipped with six photovoltaic panels (significant for the electrical aspects) and 10 kWp of thermal solar panels to be integrated in the grid.
Further technologies to be considered for the E-NERDD are power plants based on other renewable resource (e.g. with biomass fuel). These systems are planned to be analyzed through real plants (remote connection with the field) or through virtual models based on real-time dynamic approaches.
Experimental tests related to the performance of the micro gas turbine are reported and discussed in this paper. The focus here is on machine correction curves essential to evaluate factors for quantifying ambient temperature influence on machine performance. This analysis is essential for setting the thermal distribution grid and for future optimization tests.
Improved GT Fleet Performance Evaluations by Considering Installed Compressor Blading Clearances
Authors: Wäsle J. , Cameron D. , Schabacker J. 
Published: July 2013

The product development process for gas turbines relies upon the understanding of the existing engine fleet. For this reason, performance measurement data are regularly collected. The processed data show a remaining scatter, which complicates the direct use of the fleet evaluation results. This scatter can be attributed to e.g. the measurement chain, existing hardware condition, and hardware installation. To understand the true engine performance, the contributing factors behind the scatter must be addressed.
This paper describes the influence of compressor blading clearances on gas turbine performance. Fleet evaluation results are first presented. The scatter in the resulting parameters (i.e.: compressor efficiency and mass flow rate, turbine efficiency) cannot be explained simply by uncertainty in the performance measurement data. Therefore, an empirical model has been developed which correlates measured compressor clearances with deviations in component efficiencies in order to understand the end effect on engine performance.
The evaluation shows a correlation between the weighted average clearances and compressor blading efficiencies. Thus, one of the contributors to the data scatter has been identified and quantified by using the empirical model and statistical analysis. The result demonstrates a method to reduce uncertainties in the fleet data and consequently improve the component understanding.
How Combined Cycle Configuration is Impacted by Current Power Market Requirements
Authors: Zachary Justin 
Published: July 2013

In the past 20 years, the equipment manufacturers have made significant strives to develop better and more cost effective products: gas turbines, steam turbines, Heat Recovery Steam Generators (HRSG), water treatment, fuel treatment equipment etc. Consequently, the Combined Cycle Power Plants (CCPP) have become, due to many technological breakthroughs, the most efficient form of electrical power generation from fossil fuel, reaching or exceeding net efficiencies of 60%. We are also witnessing a substantial penetration of Renewable in the power generation mix. The Renewable intermittent nature of generation associated with new grid requirements for spinning reserves and/or frequency control must be considered when new CCPP are conceptually designed.
The paper will examine several CCPP configurations, involving one, two, and three gas turbines. Substantial improvements in the efficiency are usually associated with an increased gas turbines electrical output. Various scenarios of plant configurations with targeted, sensible level of integration will be examined.
The challenges of major equipment selection (gas turbines, heat recovery steam generator steam turbines, heat sink) for each of the configurations will be examined from an EPC (Engineering, Procurement, Construction) Contractor perspective, based on the lessons learned from the development and execution of more than 30 advanced CCPPs.
A special emphasis will be given to the strategy of providing the CCPP with fast start-up, capability, rapid load changes, without negatively impacting part-load efficiencies and emissions. The effect of plant configuration on plant reliability, maintenance requirements and recommended spare parts will also be discussed.
Finally the paper describes the lessons learned, in plant configuration selection that can be successfully employed on future projects through judicious equipment selection at the development phase, design optimization and proper project management at the execution phase.
On the Stability of Transonic Compressor With Wet Compression and Blade Tip Water Injection
Authors: Luo Mingcong , Zheng Qun , Sun Lanxin , Deng Qingfeng , Chen Jiyou , Wang Jie , Bhargava Rakesh K. 
Published: July 2013

The rotor blade tip leakage flow and associated formation of the tip leakage vortex and interaction of the tip leakage vortex with the shockwave, particularly in the case of a transonic compressor rotor have significant impact on the compressor performance and its stability. Air injection upstream of the compressor rotor tip has been shown to improve compressor performance and enhance its stability. The air required for rotor blade tip injection is generally taken from the later stages of the compressor thus causing penalty on the gas turbine performance. In this study, effects of water injection at the rotor tip with and without the wet compression on the compressor performance and its stability have been examined. To achieve the stated objectives, the well tested transonic compressor rotor stage, NASA rotor stage 37, has been numerically simulated.
The evaluation of results on various performance parameters such as total pressure ratio, inlet flow capacity and adiabatic efficiency combined with contours of total pressure losses, entropy, Mach No., and temperature including limiting streamlines, shows that the blade tip water injection could help in reducing low energy region downstream of the shockwave and strength of the tip leakage vortex with the compressor operating at its rotating stall boundary condition. The extent of reduction depends on the droplet size, injection flow rate and its velocity. Furthermore, results show that combined case of the blade tip water injection and the wet compression could provide better stall margin enhancement than the blade tip water injection case.
Modelling Contra-Rotating Turbomachinery Components for Engine Performance Simulations: The Geared Turbofan With Contra-Rotating Core Case
Authors: Alexiou A. , Roumeliotis I. , Aretakis N. , Tsalavoutas A. , Mathioudakis K. 
Published: July 2013

This paper presents a method of modelling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at component and engine level.
Using this approach, a performance model of a geared turbofan with a Contra-Rotating Core (CRC) is created. This configuration was investigated in the context of the European program NEWAC (NEW Aero-engine core Concepts). The core consists of a seven-stage compressor and a two-stage turbine without inter-stage stators and with successive rotors running in opposite direction through the introduction of a rotating outer spool. Such a configuration results in reduced parts count, length, weight and cost of the entire HP system. Additionally, the core efficiency is improved due to reduced cooling air flow requirements.
The model is then coupled to an aircraft performance model and a typical mission is carried out. The results are compared against those of a similar configuration employing a conventional core and identical design point performance. For the given aircraft-mission combination and assuming a 10% engine weight saving when using the CRC arrangement over the conventional one, a total fuel burn reduction of 1.1% is predicted.
CO2 Capture From Air-Blown Gasification-Based Combined Cycles
Authors: Giuffrida Antonio , Romano Matteo C. , Lozza Giovanni 
Published: July 2013

This paper focuses on an air-blown gasification-based combined cycle where CO2 is removed from the coal-derived gas before fuelling the combustion turbine. On the basis of public information from Mitsubishi Heavy Industries (MHI), the air-blown gasifier was modeled and its performance was investigated by the authors in a previous study. Here, with reference to a possible IGCC power plant with such a gasification technology, the possibility of removing CO2 from the coal-derived fuel gas is considered. The main differences between the two IGCCs, without and with CO2 capture, are gas used for coal loading (N2 or CO2), the layout of the syngas cooling and treatment sections (owing to the presence of watergas shift reactions and CO2 absorption process) and the composition of the fuel used in the combustion turbine. The results highlight that IGCC efficiency reduces by about 10.8% points when realizing CO2 capture, mainly due to the steam consumption in shift reactors and CO2 solvent regeneration and to power consumption for CO2 compression. However, the calculated efficiency penalty is in line with the values typical of IGCCs with oxygen-blown gasifier and CO2 capture.
The power balances of the assessed cases are reported in detail and the main technical issues are discussed in the paper. The results of a sensitivity analysis are also reported to assess the effects of different steam to carbon ratios in the shift reactors.
Oxy-Fuel Turbomachinery Development for Energy Intensive Industrial Applications
Authors: Hollis Rebecca , Skutley Patrick , Ortiz Carlos , Varkey Vijo , LePage Danise , Brown Barry , Davies Daniel , Harris Mark 
Published: July 2013

Future fossil-fueled power generation systems will require emission control technologies such as carbon capture and sequestration (CCS) to comply with government greenhouse gas regulations. The three prime candidate technologies which permit carbon dioxide (CO2) to be captured and safely stored include pre-combustion, post-combustion capture and oxy-fuel (O-F) combustion. For more than a decade Clean Energy Systems, Inc. (CES) has been designing and demonstrating enabling technologies for oxy-fuel power generation; specifically steam generators, hot gas expanders and reheat combustors.
Recently CES has partnered with Florida Turbine Technologies, Inc. (FTT) and Siemens Energy, Inc. to develop and demonstrate turbomachinery systems compatible with the unique characteristics of oxy-fuel working fluids. The team has adopted an aggressive, but economically viable development approach to advance turbine technology towards early product realization. Goals include short-term, incremental advances in power plant efficiency and output while minimizing capital costs and cost of electricity.
Phase 2 of this development work has been greatly enhanced by a cooperative agreement with the U.S. Department of Energy (DOE). Under this program the team will design, manufacture and test a commercial-scale intermediate-pressure turbine (IPT) to be used in industrial O-F power plants. These plants will use diverse fuels and be capable of capturing 99% of the produced CO2 at competitive cycle efficiencies and cost of electricity. Initial plants will burn natural gas and generate more than 200MWe with near-zero emissions.
To reduce development cost and schedule an existing gas turbine engine will be adapted for use as a high-temperature O-F IPT. The necessary modifications include the replacement of the engine’s air compressor with a thrust balance system and altering the engine’s air-breathing combustion system into a steam reheating system using direct fuel and oxygen injection.
Excellent progress has been made to date. FTT has completed the detailed design and issued manufacturing drawings to convert a Siemens SGT-900 to an oxy-fuel turbine (OFT). Siemens has received, disassembled and inspected an SGT-900 B12 and ordered all necessary new components for engine changeover. Meanwhile CES has been working to upgrade an existing test facility to support demonstration of a “simple” oxy-fuel power cycle. Low-power demonstration testing of the newly assembled OFT-900 is expected to commence in late 2012.
Stability of deflected-beam metal–insulator–metal tunneling cathodes under high acceleration voltage
Authors: Suzuki Mutsumi , Kusunoki Toshiaki 
Published: July 2013

Metal–insulator–metal (MIM) tunneling cathodes have advantageous features, such as areal electron beams and robustness to surface contamination. Therefore, they are suitable for field-emission displays. This paper reports the long-term stability of MIM tunneling cathodes in display panels operating under a high acceleration voltage (anode voltage). A preliminary life test was carried out using conventional display panels, which consisted of a phosphor-coated anode plate and a cathode plate having matrix-arrayed cathodes. The life test indicated that the pace at which cathodes degrade increases significantly when the acceleration voltage exceeds a few kilovolts. This high-voltage (HV)-induced degradation is presumably attributed to cathodes being bombarded by positive ions originating from residual gases. To suppress HV-induced degradation, the authors propose the concept of a deflected-beam cathode, in which electron beams are deflected so that the recoiling ions fail to hit the cathode. This concept was implemented by introducing deflector electrodes in the cathode plate, thereby forming an electron lens in each pixel. As 6-μm high scan lines were used as the deflector electrodes in this design, the deflected-beam cathodes could be fabricated only by modifying the pattern of the scan lines. The authors also present a simulation-based design procedure using an emitter-landing diagram, which facilitates analysis of the margins for the deflected-beam cathodes. The deflected-beam cathodes thus designed were incorporated into 3.8 cm-diagonal test panels to confirm the validity of the concept. The degree of beam deflection that was observed was in excellent agreement with the results obtained from simulation. A life test extending over a 20 000-h period demonstrated that the HV-induced degradation was suppressed with the deflected-beam MIM cathodes.
Loss of Very-Long O-Antigen Chains Optimizes Capsule-Mediated Immune Evasion by Salmonella enterica Serovar Typhi
Authors: Crawford Robert W. , Wangdi Tamding , Spees Alanna M. , Xavier Mariana N. , Tsolis Renée M. , Bäumler Andreas J. 
Published: July 2013

ABSTRACT

Expression of capsular polysaccharides is a variable trait often associated with more-virulent forms of a bacterial species. For example, typhoid fever is caused by the capsulated
Salmonella enterica
serovar Typhi, while nontyphoidal
Salmonella
serovars associated with gastroenteritis are noncapsulated. Here we show that optimization of the immune evasive properties conferred by the virulence-associated (Vi) capsular polysaccharide involved an additional alteration to the cell envelope of
S
. Typhi, namely inactivation of the
fepE
gene, encoding the regulator of very-long O-antigen chains. Introduction of the capsule-encoding
viaB
locus into the nontyphoidal
S. enterica
serovar Typhimurium reduced complement deposition
in vitro
and intestinal inflammation in a mouse colitis model. However, both phenotypes were markedly enhanced when the
viaB
locus was introduced into an
S
. Typhimurium
fepE
mutant, which lacks very-long O-antigen chains. Collectively, these data suggest that during the evolution of the
S
. Typhi lineage, loss of very-long O-antigen chains by pseudogene formation was an adaptation to maximize the anti-inflammatory properties of the Vi capsular polysaccharide.

IMPORTANCE
Genomic comparison illustrates that acquisition of virulence factors by horizontal gene transfer is an important contributor to the evolution of enteric pathogens. Acquisition of complex virulence traits commonly involves horizontal transfer of a large gene cluster, and integration of the gene cluster into the host genome results in the formation of a pathogenicity island. Acquisition of the virulence-associated (Vi) capsular polysaccharide encoded by SPI7 (
Salmonella
pathogenicity island 7) was accompanied in the human-adapted
Salmonella enterica
serovar Typhi by inactivation of the
fepE
gene, encoding the regulator of very-long O-antigen chains. We show that the resulting loss of very-long O-antigen chains was an important mechanism for maximizing immune evasion mediated by the Vi capsular polysaccharide. These data suggest that successful incorporation of a capsular polysaccharide requires changes in the cell envelope of the hosting pathogen.
A Mouse Model for Human Norovirus
Authors: Taube Stefan , Kolawole Abimbola O. , Höhne Marina , Wilkinson John E. , Handley Scott A. , Perry Jeffrey W. , Thackray Larissa B. , Akkina Ramesh , Wobus Christiane E. 
Published: July 2013

ABSTRACT

Human noroviruses (HuNoVs) cause significant morbidity and mortality worldwide. However, despite substantial efforts, a small-animal model for HuNoV has not been described to date. Since “humanized” mice have been successfully used to study human-tropic pathogens in the past, we challenged BALB/c mice deficient in recombination activation gene (Rag) 1 or 2 and common gamma chain (γc) (Rag-γc) engrafted with human CD34
+
hematopoietic stem cells, nonengrafted siblings, and immunocompetent wild-type controls with pooled stool isolates from patients positive for HuNoV. Surprisingly, both humanized and nonhumanized BALB/c Rag-γc-deficient mice supported replication of a GII.4 strain of HuNoV, as indicated by increased viral loads over input. In contrast, immunocompetent wild-type BALB/c mice were not infected. An intraperitoneal route of infection and the BALB/c genetic background were important for facilitating a subclinical HuNoV infection of Rag-γc-deficient mice. Expression of structural and nonstructural proteins was detected in cells with macrophage-like morphology in the spleens and livers of BALB/c Rag-γc-deficient mice, confirming the ability of HuNoV to replicate in a mouse model. In summary, HuNoV replication in BALB/c Rag-γc-deficient mice is dependent on the immune-deficient status of the host but not on the presence of human immune cells and provides the first genetically manipulable small-animal model for studying HuNoV infection.

IMPORTANCE
Human noroviruses are a significant cause of viral gastroenteritis worldwide, resulting in significant morbidity and mortality. Antivirals and vaccines are currently not available, in part due to the inability to study these viruses in a genetically manipulable, small-animal model. Herein, we report the first mouse model for human noroviruses. This model will accelerate our understanding of human norovirus biology and provide a useful resource for evaluating antiviral therapies.
Diagnosis and acute management of patients with concussion at children's hospitals
Authors: Colvin Jeffrey D , Thurm Cary , Pate Brian M , Newland Jason G , Hall Matt , Meehan William P 
Published: July 2013

ObjectivesTo describe the number of hospital admissions for concussion at paediatric hospitals in the USA. To describe the use of imaging and medications for acute concussion paediatric patients.DesignCross-sectional study.SettingChildren's hospitals participating in the Pediatric Health Information System in the USA during a 10-year period.PatientsAll emergency department (ED) visits and inpatient admissions with the primary diagnosis of concussion, defined as International Classification of Diseases, Ninth Revision, Clinical Modification codes for: (1) concussion, (2) postconcussion syndrome or (3) skull fracture without mention of intracranial injury with concussion.Main outcome measuresThe proportion of concussion patients who were hospitalised, underwent imaging or received medication, and the adjusted costs of visits for concussion.ResultsThe number of ED visits for concussion increased between 2001 and 2010 (2126 (0.36% of all ED visits) vs 4967 (0.62% of all ED visits); p<0.001), while the number of admissions remained stable. Of ED visits for concussion, 59.9% received CT and 47.7% received medications or intravenous fluids. Non-narcotic analgesics were the most common medication administered. Adjusted costs of patient visits were significantly higher when imaging was obtained (US$695, IQR US$472–$1009, vs US$191, IQR US$114–$287). An ED visit with CT, however, cost less than a hospitalisation without CT (US$1907, IQR US$1292–$3770).ConclusionsAlthough the number of ED patients diagnosed with concussion has increased, the number admitted has remained stable. Concussion patients at paediatric hospitals in the USA commonly undergo CT imaging and receive medication.
Take your shoes off to reduce patellofemoral joint stress during running
Authors: Bonacci Jason , Vicenzino Bill , Spratford Wayne , Collins Paul 
Published: July 2013

AimElevated patellofemoral joint stress is thought to contribute to the development and progression of patellofemoral pain syndrome. The purpose of this study was to determine if running barefoot decreases patellofemoral joint stress in comparison to shod running.MethodsLower extremity kinematics and ground reaction force data were collected from 22 trained runners during overground running while barefoot and in a neutral running shoe. The kinematic and kinetic data were used as input variables into a previously described mathematical model to determine patellofemoral joint stress. Knee flexion angle, net knee extension moment and the model outputs of contact area, patellofemoral joint reaction force and patellofemoral joint stress were plotted over the stance phase of the gait cycle and peak values compared using paired t tests and standardised mean differences calculated.ResultsRunning barefoot decreased peak patellofemoral joint stress by 12% (p=0.000) in comparison to shod running. The reduction in patellofemoral joint stress was a result of reduced patellofemoral joint reaction forces (12%, p=0.000) while running barefoot.ConclusionsElevated patellofemoral joint stress during shod running might contribute to patellofemoral pain. Running barefoot decreases patellofemoral joint stress.