bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research Review: Polygenic methods and their application to psychiatric traits
Authors: Wray Naomi R. , Lee Sang Hong , Mehta Divya , Vinkhuyzen Anna A.E. , Dudbridge Frank , Middeldorp Christel M. 
Published: August 2014

BackgroundDespite evidence from twin and family studies for an important contribution of genetic factors to both childhood and adult onset psychiatric disorders, identifying robustly associated specific DNA variants has proved challenging. In the pregenomics era the genetic architecture (number, frequency and effect size of risk variants) of complex genetic disorders was unknown. Empirical evidence for the genetic architecture of psychiatric disorders is emerging from the genetic studies of the last 5 years.Methods and scopeWe review the methods investigating the polygenic nature of complex disorders. We provide mini‐guides to genomic profile (or polygenic) risk scoring and to estimation of variance (or heritability) from common SNPs; a glossary of key terms is also provided. We review results of applications of the methods to psychiatric disorders and related traits and consider how these methods inform on missing heritability, hidden heritability and still‐missing heritability.FindingsGenome‐wide genotyping and sequencing studies are providing evidence that psychiatric disorders are truly polygenic, that is they have a genetic architecture of many genetic variants, including risk variants that are both common and rare in the population. Sample sizes published to date are mostly underpowered to detect effect sizes of the magnitude presented by nature, and these effect sizes may be constrained by the biological validity of the diagnostic constructs.ConclusionsIncreasing the sample size for genome wide association studies of psychiatric disorders will lead to the identification of more associated genetic variants, as already found for schizophrenia. These loci provide the starting point of functional analyses that might eventually lead to new prevention and treatment options and to improved biological validity of diagnostic constructs. Polygenic analyses will contribute further to our understanding of complex genetic traits as sample sizes increase and as sample resources become richer in phenotypic descriptors, both in terms of clinical symptoms and of nongenetic risk factors.
Prostaglandin E2 as a read out for endotoxin detection in a bovine whole blood assay
Authors: Wunderlich C. , Schumacher S. , Kietzmann M. 
Published: August 2014

The detection of endotoxin contamination is an essential part of drug safety testing. The rabbit pyrogen test (RPT), the limulus amoebocyte lysate (LAL) test, and the monocyte activation test (MAT) are established methods for the detection of pyrogens. However, the RPT is insufficiently standardized; the LAL test is solely capable of identifying the presence of endotoxins, whereas the use of the MAT is limited by the availability of human blood. Here, we introduce a new procedure for testing endotoxin contamination using prostaglandin E2 (PGE2) release from bovine whole blood. We incubated bovine whole blood overnight with lipopolysaccharide (LPS) from Escherichia coli 0111:B4, concentrations ranging from 1.56 to 12.5 pg/mL, and found significantly increased PGE2 production for even the lowest LPS concentrations. Testing the possibility of storing the blood at 4 °C before use also yielded positive results as 1.56 pg/mL still significantly increased PGE2 production, thus suggesting some flexibility of the assay regarding time. These results emphasize the potential of using bovine whole blood for highly sensitive endotoxin testing. As a perspective, currently ongoing research aims to show whether the assay is also capable of detecting nonendotoxin pyrogens.
Mixed signals from hybrid genomes
Authors: Orozco‐terWengel Pablo A. , Bruford Michael W. 
Published: August 2014

Admixture results from interbreeding between individuals from different populations or species that were previously genetically isolated from each other (Fig. ). Identifying admixture events in the genome is not always a straightforward task, because the genetic signature left behind fades with time as recombination events fragment the genomic segments introduced during the interbreeding event. Additionally, when the genetic architecture of populations or species that admix is not very different (e.g. they coalesce to a common ancestor recently), admixture signatures may be difficult to detect. Ignoring the effects of admixture can, however, pose severe problems for population genetic analyses that rely on the distribution of polymorphic markers across the genome. In this issue of Molecular Ecology, Bosse et al. () analyse genomic data from modern pigs to understand hybridization processes that occurred between domestic pigs from European and Asiatic origin, and between pigs and wild boars. Their results are interesting regarding the fine‐scale distribution of admixture across the pig genome, and the way in which this admixture biases estimates of the effective population size in European domestic pigs. The implications of these results are significant, as they serve as a cautionary note on genomic analyses that depend on the distribution of polymorphic variants in potentially admixed populations.
Distribution of permanent canine agenesis in Down syndrome: 15 cases from a Centre for Special Care Dentistry
Authors: Reuland‐Bosma Wimke , Reuland Merijn C. , Bronkhorst Ewald 
Published: August 2014

ABSTRACTThe purpose of this study was to investigate the distribution of permanent canine agenesis in subjects with Down syndrome (DS). Subjects with canine agenesis were determined by means of panoramic radiographs from 150 DS subjects attending a center for special care dentistry. Our results confirm the high prevalence of agenetic canines in DS (21 canines, 14%). We found specific effects on the distribution both of phenotype and of location (jaw). In subjects with a mild expression of hypodontia (phenotype nonoligodontia) agenetic canines primarily occurred in the mandibula, whereas in subjects with severe hypodontia (phenotype oligodontia) agenetic canines virtually only occurred in the maxilla. In both phenotypes cooccurrence of an agenetic lateral incisor with an agenetic canine was observed in the maxilla. It was striking that canine agenesis in the mandibula did not cooccur with agenesis of other teeth. These results can be important for treatment planning.
GSP, a Generic Object-Oriented Gas Turbine Simulation Environment
Authors: Visser Wilfried P. J. , Broomhead Michael J. 
Published: August 2014

NLR’s primary tool for gas turbine engine performance analysis is the ‘Gas turbine Simulation Program’ (GSP), a component based modeling environment. GSP’s flexible object-oriented architecture allows steady-state and transient simulation of any gas turbine configuration using a user-friendly drag&drop interface with on-line help running under Windows95/98/NT.
GSP has been used for a variety of applications such as various types of off-design performance analysis, emission calculations, control system design and diagnostics of both aircraft and industrial gas turbines. More advanced applications include analysis of recuperated turboshaft engine performance, lift-fan STOVL propulsion systems, control logic validation and analysis of thermal load calculation for hot section life consumption modeling.
In this paper the GSP modeling system and object-oriented architecture are described. Examples of applications for both aircraft and industrial gas turbine performance analysis are presented.
Integration of Advanced Gas Turbines in Pulp and Paper Mills for Increased Power Generation
Authors: Maunsbach Katarina , Isaksson Anna , Yan Jinyue , Svedberg Gunnar , Eidensten Lars 
Published: August 2014

The pulp and paper industry handles large amounts of energy and today produces the steam needed for the process and some of the required electricity. Several studies have shown that black liquor gasification and combined cycles increase the power production significantly compared to the traditional processes used today. It is of interest to investigate the performance when advanced gas turbines are integrated with next-generation pulp and paper mills. The present study focused on comparing the combined cycle with the integration of advanced gas turbines such as steam injected gas turbine (STIG) and evaporative gas turbine (EvGT) in pulp and paper mills.
Two categories of simulations have been performed: (1) comparison of gasification of both black liquor and biomass connected to either a combined cycle or steam injected gas turbine with a heat recovery steam generator; (2) externally fired gas turbine in combination with the traditional recovery boiler. The energy demand of the pulp and paper mills is satisfied in all cases and the possibility to deliver a power surplus for external use is verified. The study investigates new system combinations of applications for advanced gas turbines.
Simulation of Steam-Based Gasification Processes for Topping Combustion in the Biomass Air Turbine (BAT) Cycle
Authors: Wolf Jens , Yan Jinyue 
Published: August 2014

In this work, steam-based gasification is investigated as a technology for fuel gas production for topping combustion in a biomass air turbine (BAT) cycle. For different systems, based on flash or conventional pyrolysis, the characteristics of the product gas quality are studied. The gas composition and the heating value of the produced gas are simulated by changing the main system parameters such as the moisture content of the biomass, the operating temperature and the composition of the biomass.
A model of the gasification process has been developed to evaluate each process. The model is based on mass conservation, the thermodynamic equilibrium of the water-gas-shift reaction and the methane yield during pyrolysis.
A gasification system with flash pyrolysis is identified as a promising technology for fuel gas production for use in topping combustion. The major features of the system are: first, the system provides a gas with a heating value of near to 16 MJ/Nm3 and small amounts of nitrogen gas; second, the application of a water knock out unit eliminates the influence of the water content in the feedstock on the product gas quality; third, the gasification process can be conducted in a tubular reactor within the furnace of the BAT cycle. This reduces the number of reactors and keeps the costs low.
Development of Low NOx Combustion Technology in Medium-Btu Fueled 1300 °C-Class Gas Turbine Combustor in IGCC
Authors: Hasegawa Takeharu , Hisamatsu Tohru , Katsuki Yasunari , Sato Mikio , Koizumi Hiromi , Hayashi Akinori , Kobayasi Nariyoshi 
Published: August 2014

The development of integrated coal gasification combined cycle (IGCC) systems ensures higher thermal efficiency and environmentally sound options for supplying future coal utilizing power generation needs. The Japanese government and electric power industries in Japan promoted research and development of an IGCC system using an air-blown entrained-flow coal gasifier. On the other hand, Europe and the United States are now developing the oxygen-blown IGCC demonstration plants.
Gasified coal fuel produced in an oxygen-blown entrained-flow coal gasifier, has a calorific value of 8–13MJ/m3 which is only 1/5–1/3 that of natural gas. However, the flame temperature of medium-Btu gasified coal fuel is higher than that of natural gas and so NOx production from nitrogen fixation is expected to increase significantly. In the oxygen-blown IGCC, a surplus nitrogen produced in the air-separation unit (ASU) is premixed with gasified coal fuel (medium-Btu fuel) and injected into the combustor, to reduce thermal-NOx production and to recover the power used for the ASU. In this case, the power to compress nitrogen increases. Low NOx emission technology which is capable of decreasing the power to compress nitrogen is a significant advance in gas turbine development with an oxygen-blown IGCC system. Analyses confirmed that the thermal efficiency of the plant improved by approximately 0.3 percent (absolute) by means of nitrogen direct injection into the combustor, compared with a case where nitrogen is premixed with gasified coal fuel before injection into the combustor.
In this study, based on the fundamental test results using a small diffusion burner and a model combustor, we designed the combustor in which the nitrogen injection nozzles arranged on the burner were combined with the lean combustion technique for low-NOx emission. In this way, we could reduce the high temperature region, where originated the thermal-NOx production, near the burner positively. And then, a combustor with a swirling nitrogen injection function used for a gas turbine, was designed and constructed, and its performance was evaluated under pressurized conditions of actual operations using a simulated gasified coal fuel. From the combustion test results, the thermal-NOx emission decreased under 11ppm (corrected at 16% O2), combustion efficiency was higher than 99.9% at any gas turbine load. Moreover, there was different effects of pressure on thermal-NOx emission in medium-Btu fuel fired combustor from the case of natural gas fired combustor.
Gas Turbine Mach Number Control With Simplified Fuel System
Authors: Dadd Graham J. , Chan Kin K. 
Published: August 2014

The compressor exit Mach number control theory presented here will enable improved control of transient compressor working point trajectories of a turbine engine. This will allow the steady working line to be raised towards the surge boundary with the advantage of increased thrust and reduced specific fuel consumption. This new control method can replace the rigid acceleration and deceleration limiters of the fuel control loop, and achieve superior surge avoidance performance.
This paper documents the theoretical and practical study of Mach number controllers designed for implementation with a simplified fuel pump system and the subsequent testing of the controllers on an aero-engine in the sea level test bed in DERA Pyestock.
The new controller incorporated two Mach number dynamic limiting control loops (one each for acceleration and deceleration) besides the NH controller. Several designs were tested successfully and demonstrated not only Mach number control from idle to full power, but also surge avoidance. Engine start control was also tested in the latest engine test.
A Fiber-Optic Tip-Shroud Deflection Measurement System
Authors: Rooth Rudy A. , Hiemstra Wiebren 
Published: August 2014

A dutch utility faced the fact that a second stage set of turbine blades of a gas turbine had to be replaced long before the estimated lifetime as a result of tip shroud deflection. This deflection caused the risk of loss of support between the individual tip shroud segments. The goal is to find the cause of the problem, to see how it increases with time and to take appropriate action to prevent the problem from occurring again.
A fiber-optic tip-shroud deflection monitor has been developed and tested on a gas turbine (Davinson, 1987) to study this phenomenon in real time.. The optical system is based on astigmatism to derive distance information from the measured optical signals. Characteristic features from the system are the good spatial resolution of about 1 millimeter, the distance resolution of about 0.1 millimeter and the distance from the probe tip to the target of about 20 millimeter. These specifications are difficult to achieve with for example capacitive sensors. The probe tip can withstand temperatures of about 500 °C. The system can be calibrated in situ, given a stable operation of the gas turbine. This is accomplished by stepping the probe tip over some distance and recording the signals corresponding to a certain point on the tip shroud. The instrument has been used to monitor the tip-shroud deflection in a gas turbine at various loads and over a time span of several months. The results indicate that the deflection can be divided in a part depending on the load and a part that is a permanent deflection. Based on the results, it can be judged whether blades need to be rejected because of a too large deflection.
Application of On-Line Optimization Technology to Plant Operation
Authors: Gay Rodney R. 
Published: August 2014

Traditionally optimization has been thought of as a technology to set power plant controllable parameters (i.e. gas turbine power levels, duct burner fuel flows, auxiliary boiler fuel flows or bypass/letdown flows) so as to maximize plant operations. However, there are additional applications of optimizer technology that may be even more beneficial than simply finding the best control settings for current operation. Most smaller, simpler power plants (such as a single gas turbine in combined cycle operation) perceive little need for on-line optimization, but in fact could benefit significantly from the application of optimizer technology.
An optimizer must contain a mathematical model of the power plant performance and of the economic revenue and cost streams associated with the plant. This model can be exercised in the “what-if” mode to supply valuable on-line information to the plant operators. The following quantities can be calculated:
Target Heat Rate
Correction of Current Plant Operation to Guarantee Conditions
Current Power Generation Capacity (Availability)
Average Cost of a Megawatt Produced
Cost of Last Megawatt
Cost of Process Steam Produced
Cost of Last Pound of Process Steam
Heat Rate Increment Due to Load Change
Prediction of Future Power Generation Capability (24 Hour Prediction)
Prediction of Future Fuel Consumption (24 Hour Prediction)
Impact of Equipment Operational Constraints
Impact of Maintenance Actions
Plant Budget Analysis
Comparison of Various Operational Strategies Over Time
Evaluation of Plant Upgrades
The paper describes examples of optimizer applications other than the on-line computation of control setting that have provided benefit to plant operators. Actual plant data will be used to illustrate the examples.
A High-Temperature Catalytic Combustor With Starting Burner
Authors: Yoshida Yusaku , Oyakawa Kenshun , Aizawa Yukio , Kaya Hiroshi 
Published: August 2014

A catalytic combustion system has high potential to achieve low NOx emission level. When this combustion system is applied to a gas turbine, the required combustor performance must be maintained over a wide range of operating conditions. These conditions range from cold starting to steady-state operation. Particularly during the initial stage of cold starting when the catalyst is not yet activated, the catalyst must be heated by some means.
This study proposes a new concept of a catalytic combustor with a direct heating system using vaporizing tube for starting burner in order to downsize the combustor and reduce the warm-up time during cold starts. The effectiveness of this concept is experimentally verified. Furthermore, NOx, CO, and HC emissions during startup can be reduced to a low level so as to achieve ultra-low pollution of the catalytic combustion over a wide range of operating conditions from cold start to steady-state operation.
This paper outlines the operation concept covering cold start, verification of the concept through the experiments with flame visualization in the combustor, spray characteristics, construction of the combustor, and combustion characteristics that show low pollution in various operating conditions of the catalytic combustor.
Ignition Delay Time Modulation as a Contribution to Thermo-Acoustic Instability in Sequential Combustion
Authors: Ni Alexander , Polifke Wolfgang , Joos Franz 
Published: August 2014

Pressure pulsations due to combustion instabilities have been encountered in a premixed sequential gas turbine combustor. Measured noise spectra display one or several distinct peaks at Strouhal numbers significantly larger than unity. Height and location of the peaks depend in a sensitve manner on fuel type and/or operating conditions.
The paper identifies a possible mechanism of the observed combustion instability and presents a mathematical model of acoustic self-excitation. The mechanism of self-excitation comprises interactions between the acoustic field in the fuel injector / burner with the ignition delay time of the fuel-air mixture and the heat release intensity:
• pressure drop in the fuel injector nozzle changes with variations of the acoustic pressure in the burner,
• variations of pressure drop and air flow velocity modulate the fuel concentration,
• acoustic perturbations in the pre-flame region influence the delay time for self-ignition and consequently lead to fluctuations of flame velocity and -position.
• fluctuations of flame velocity influence the refracation of acoustic waves at the flame front.
• fuel inhomogeneities modulate the heat release rate and consequently the rate of volume production by the flame.
Based on this structure of a self-excitation mechanism, an analytical model has been developed and used to compute eigenfrequencies and growth rates of instabilities. Some characteristics of the suggested self-excitated instabilities as they are predicted by the model match well with empirical information.
Computational Modelling of Self-Excited Combustion Instabilities
Authors: Brookes Steve J. , Cant R. Stewart , Dupere Iain D. J. , Dowling Ann P. 
Published: August 2014

It is well known that lean premixed combustion systems potentially offer better emissions performance than conventional non-premixed designs. However, premixed combustion systems are more susceptible to combustion instabilities than non-premixed systems. Combustion instabilities (large-scale oscillations in heat release and pressure) have a deleterious effect on equipment, and also tend to decrease combustion efficiency. Designing out combustion instabilities is a difficult process and, particularly if many large-scale experiments are required, also very costly. Computational fluid dynamics (CFD) is now an established design tool in many areas of gas turbine design. However, its accuracy in the prediction of combustion instabilities is not yet proven.
Unsteady heat release will generally be coupled to unsteady flow conditions within the combustor. In principle, computational fluid dynamics should be capable of modelling this coupled process. The present work assesses the ability of CFD to model self-excited combustion instabilities occurring within a model combustor. The accuracy of CFD in predicting both the onset and the nature of the instability is reported.
Dual Fuel Dry Low Emissions (DLE) Combustion System for the ABB Alstom Power 13,4 MW Cyclone Gas Turbine
Authors: Alkabie H. , McMillan R. , Noden R. , Morris C. 
Published: August 2014

In response to stringent environmental legislation and customer demands for improved thermal efficiency, ABB ALSTOM POWER UK Ltd has introduced the 13.4MW Cyclone gas turbine engine. In this machine higher efficiency is achieved by increased firing temperature and pressure ratio. In order to meet the environmental considerations the Cyclone is supplied with Dual Fuel DLE combustion system as standard. Successful operation of the combustion system required a careful balance between the component life and low emissions performance. The combustor performance specification included targets for the following parameters:-
• Low emissions, NOx, CO, UHC and smoke, on both gaseous and liquid fuels without water or steam injection
• Good turn down ratio
• Controlled combustor outlet temperature profiles, both OTDF and RTDF
• Low dynamic pressure fluctuations
• Reliable ignition and fuel change over on both gas and liquid.
• Reliable transient response
This paper describes the design and validation work undertaken in order to achieve these challenging targets. It is shown that these targets are not only achieved but in some cases exceeded resulting in an economical and environmentally sound combustion system.