bluuebunny/crossref_metadata_2025_split huggingface dataset:
Educational outcome in adolescence following pyloric stenosis repair before 3 months of age: a nationwide cohort study
Authors: Hansen Tom G. , Pedersen Jacob K. , Henneberg Steen W. , Morton Neil S. , Christensen Kaare 
Published: July 2013

SummaryBackgroundImmature animals exposed to anesthetics display apoptotic neurodegeneration with subsequent long‐term cognitive dysfunctions. Young age at anesthetic exposure is believed to be critical, but human studies are scarce. This study investigated the association between exposure to surgery and anesthesia for pyloric stenosis (PS) before 3 months of age and subsequent educational outcome in adolescence.MethodsThis nationwide unselected register‐based follow‐up study of the Danish birth cohorts 1986–1990 compared the educational outcome of all children having undergone surgery for PS before 3 months of age with a randomly selected, age‐matched 5% sample of the same cohort. Primary analysis compared the average test scores at ninth grade adjusting for gender, birth weight, and parental age and education. Secondary analysis compared the proportions not attaining the test scores between the two groups.ResultsThe exposure group comprised 779 and the control group consisted of 14 665 individuals. Although the exposure group performed lower than the control group (average score 0.17 lower, 95% CI: 0.08–0.25), after adjusting for known confounders, no statistically significant difference (−0.04, 95% CI: −0.09 to 0.08) between the 2 groups could be demonstrated. However, we found an odds ratio (OR) for test score nonattainment‐associated PS repair of 1.37 (95% CI: 1.11–1.68).ConclusionChildren operated for PS before 3 months of age have educational performance tests similar to the background population at age 15–16 years after adjusting for known confounders. The higher nonattainment rate could suggest that a subgroup of PS children is developmentally disadvantaged.
Der Wert der Reisezeit deutscher Pendler
Authors: Obermeyer Andy , Evangelinos Christos , Besherz Andreas 
Published: July 2013

Abstract
Travel time savings are usually the most important utility component of transport projects. This paper shows estimation of the value of travel time savings (VTTS) with particular focus on random parameter models. Employing these models commuters’ VTTS in the German City Dresden is estimated. Results show that travel time savings of motorised and non-motorised modes are valued differently, VTTS derived in this study are higher than values currently used in Germany’s federal transport infrastructure plan and VTTS are dependent on travel time.
Is the Provincial Capital Market Segmented in China?
Authors: Chan Kenneth , Lai Jennifer , Yan Isabel 
Published: July 2013

AbstractThis paper evaluates the degree of provincial capital mobility in China since 1978 by estimating the saving‐retention rate in the Feldstein and Horioka framework. It is found that the estimate of the saving retention rate tends to be biased downward if we fail to decompose the investment and saving rates into the private and government components. After the decomposition, we find that the private capital mobility was low prior to the 1990s, but improved notably in the more recent period. We also find that the saving‐retention rate for the government sector remains negative throughout the sample, which can partially be explained by the government's reallocation of capital from the more productive regions to the less productive regions. Comparing the results of China with those of Japan shows that Japan had a much higher degree of prefectural capital mobility than China before the 1990s, but the gap gradually closed up afterwards.
Rabies Prevention and Management of Cats in the Context of Trap–Neuter–Vaccinate–Release Programmes
Authors: Roebling A. D. , Johnson D. , Blanton J. D. , Levin M. , Slate D. , Fenwick G. , Rupprecht C. E. 
Published: July 2013

SummaryDomestic cats are an important part of many Americans' lives, but effective control of the 60–100 million feral cats living throughout the country remains problematic. Although trap–neuter–vaccinate–return (TNVR) programmes are growing in popularity as alternatives to euthanizing feral cats, their ability to adequately address disease threats and population growth within managed cat colonies is dubious. Rabies transmission via feral cats is a particular concern as demonstrated by the significant proportion of rabies post‐exposure prophylaxis associated with exposures involving cats. Moreover, TNVR has not been shown to reliably reduce feral cat colony populations because of low implementation rates, inconsistent maintenance and immigration of unsterilized cats into colonies. For these reasons, TNVR programmes are not effective methods for reducing public health concerns or for controlling feral cat populations. Instead, responsible pet ownership, universal rabies vaccination of pets and removal of strays remain integral components to control rabies and other diseases.
Considerations on the Numerical Modelling and Performance of Axial Swirlers Under Relight Conditions
Authors: Koupper Charlie , Grech Nicholas , Zachos Pavlos K. , Pachidis Vassilios , Singh Riti 
Published: July 2013

Numerical modelling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modelling, common practice is to replace the atomizer’s swirlers with velocity profiles boundary conditions, very often scaled down from nominal operating conditions assuming similarity of the swirler flowfield. The current numerical study focuses on the flowfield characteristics of an axially swirled atomizer operating within a windmilling engine environment. The scalability of the velocity profile from higher power settings is examined. Observations on the performance of the axial swirler under relight conditions are also made.
Experimental data was used as a validation platform for the numerical solver, after a grid sensitivity study and a turbulence model selection process. Boundary conditions for simulating the windmilling environment were extracted from experimental work.
The swirler axial and tangential velocity profiles were normalised using the swirler inlet velocity. Results showed that both profiles are only scalable for windmilling conditions of high flight Mach number (≥ 0.5). At low flight Mach numbers, the actual profile had a lower velocity than that predicted through scaling. The swirl number was found to deteriorate significantly with the flight velocity following a linear trend, reducing significantly the expected flame quality. As a consequence the burner is forced to operate at the edge of its stability loop with low certainty regarding its successful relight.
Wind Energy Resource Assessment and Power Production Estimates as an Undergraduate Project
Authors: Nix Andrew C. , Lawson Seth A. , Murphy Robert G. 
Published: July 2013

It is common practice to install wind-monitoring stations in geographical locations having high winds to estimate power production prior to installing large-scale wind farms. For the current study, a wind-monitoring program was developed as an educational tool for undergraduate engineering students at West Virginia University. The focus of this paper is not on the results of the assessment, but rather on how this program was used as a hands-on approach for educating students about wind energy and availability. The objective of the student/industry collaborative project was to determine the feasibility of constructing a wind farm to power a federal prison facility located in an area with an abundant wind resource in North Central West Virginia, while educating students on wind energy.
This paper presents a description and assessment of this program as an undergraduate senior design project. As part of the program, students played a key role from the developmental stages of the project, to the assessment of the results. During the first semester of the senior design project, students procured a wind monitoring station based on down-select criteria, selected the site for construction, installed the wind monitoring station, commissioned the sensor suite, and performed quality assurance/quality control (QA/QC) of and evaluated the initial data sets. Students logged data through the second semester of the program, performed data quality monitoring, processed average wind speed and direction data into frequency distributions and wind roses, analyzed monthly and diurnal averages in wind resources and performed power production calculations. Several different methodologies were employed, including application of fluid control volume energy analysis to derive Betz’ limit, turbine efficiency curves with operational limits and Weibull statistics to employ online power production estimators. The program successfully introduced students to the applicability of their engineering education to the area of renewable energy.
Evolution and Future Trend of Large Frame Gas Turbines: A New 1600 Degree C, J Class Gas Turbine
Authors: Hada Satoshi , Yuri Masanori , Masada Junichiro , Ito Eisaku , Tsukagoshi Keizo 
Published: July 2013

MHI recently developed a 1600°C class J-type gas turbine, utilizing some of the technologies developed in the National Project to promote the development of component technology for the next generation 1700°C class gas turbine.
This new frame is expected to achieve higher combined cycle efficiency and will contribute to reduce CO2 emissions.
The target combined cycle efficiency of the J type gas turbine will be above 61.5% (gross, ISO standard condition, LHV) and the 1on1 combined cycle output will reach 460MW for 60Hz engine and 670MW for 50Hz engine.
This new engine incorporates:
1) A high pressure ratio compressor based on the advanced M501H compressor, which was verified during the M501H development in 1999 and 2001.
2) Steam cooled combustor, which has accumulated extensive experience in the MHI G engine (> 1,356,000 actual operating hours).
3) State-of-art turbine designs developed through the 1700°C gas turbine component technology development program in Japanese National Project for high temperature components.
This paper discusses the technical features and the updated status of the J-type gas turbine, especially the operating condition of the J-type gas turbine in the MHI demonstration plant, T-Point.
The trial operation of the first M501J gas turbine was started at T-point in February 2011 on schedule, and major milestones of the trial operation have been met. After the trial operation, the first commercial operation has taken place as scheduled under a predominantly Daily-Start-and-Stop (DSS) mode. Afterward, MHI performed the major inspection in October 2011 in order to check the mechanical condition, and confirmed that the hot parts and other parts were in sound condition.
Analysis of an Integrated PEMFC/ORC Power System Using Ammonia for Hydrogen Storage
Authors: Borello Domenico , Del Prete Zaccaria , Marchegiani Andrea , Rispoli Franco , Tortora Eileen 
Published: July 2013

The present work deals with a high temperature proton exchange membrane (SPEEK-type) fuel cell (HT-PEMFC) energy system fuelled with hydrogen obtained by reforming of ammonia (NH3) and coupled with a bottoming Organic Rankine Cycle (ORC) energy system. This system was designed for distributed electric power generation, mainly for production of electric power systems with potential future applications in smart-grid.
The use of ammonia as hydrogen rich gas source allows to avoid hydrogen tanking with metal hydrides, giving the opportunity to lighten and simplify the storage section of the system with respect to the pure hydrogen fed systems.
The hybrid fuel cell/ORC configuration allows to increase the efficiency of standard power generation technologies. In other words, the ORC subset represents the most appropriate solution, in terms of sustainability, for extracting the excess heat produced during the H2 combustion maintaining the PEMFC working temperature at 120°C and for reducing the temperature of the exhausts.
The objective of the work is to optimize the electric output of the system (PEMFC + ORC), thus improving the overall efficiency. To this end, a numerical model is implemented and tested. A validation of the numerical scheme is carried out comparing the prediction of the reforming phase with experimental results obtained by the authors. The thermal and electrical energy balance is also assessed. Furthermore, the operation conditions of the reformer are studied in detail to determine the settlements leading to a proper ammonia cracking to produce nitrogen and hydrogen. Furthermore, the calculations take into account also the auxiliary equipments such as pumps, compressors and heat exchangers.
Demonstration of Model Based, Off-Line Performance Analysis on a Gas Turbine Air Compressor (GTAC)
Authors: Wiese Ashley P. , Blom Matthew J. , Brear Michael J. , Manzie Chris , Kitchener Anthony 
Published: July 2013

This paper presents a model based, off-line method for analysing the performance of individual components in an operating gas turbine. As with other studies, a least squares approach is employed. The component models are physics-based where possible. In its most general form, the method permits simultaneous inference of the combustor efficiency and stagnation pressure loss, the hot-end heat losses and associated heat transfer coefficients, the turbine inlet temperature and the turbine’s isentropic efficiency. As part of this, combustion of unburnt fuel within the turbine is modelled.
The method is demonstrated on a so-called ‘Gas Turbine Air Compressor (GTAC)’ test rig built by the group, a micro-turbine whose compressor supplies air for both the cycle and external applications, but produces no shaft work. The method is also formulated for other gas turbines. The highest order models are tested first, and then the model order is progressively reduced to determine adequate component model complexity. Since the GTAC is a micro-gas turbine, heat losses are found to be significant. It is also shown that care must be taken to distinguish between variations in the performance of different components, since the performance of several components can have similar effects on the complete, operating device.
Numerical Through Flow Simulation of a Gas Turbine Engine With Wet Compression
Authors: Sun Lanxin , Zheng Qun , Li Yijin , Luo Mingcong , Wang Jie , Bhargava Rakesh K. 
Published: July 2013

In this paper, a thorough flow simulation of a small turbojet engine has been carried out to predict the engine performance as a result of water injected at the compressor inlet. Wet compression will not only change compressor performance characteristic map, but also has effects on both the combustor and the turbine sections. The match between the turbojet engine components, that is the compressor, combustor and turbine, will shift to a new operating point. In this paper, we present a steady-state numerical simulation of the entire gas turbine with wet compression in order to evaluate the effects on the gas turbine performance.
Compared with the dry case, the results of wet cases show increased values of compressor compression ratios, turbine expansion ratios, intake mass flowrates and engine thrusts including decreased amount of specific fuel consumption. The wet compression reduces NOx production in the combustor, which is also simulated and results presented. The study also indicates that the water mass flowrate and droplet diameter are key factors impacting the engine performance.
Technical and Economic Analysis of the Gas Turbine Air Bottoming Cycle
Authors: Chmielniak Tadeusz , Czaja Daniel , Lepszy Sebastian 
Published: July 2013

The gas turbine engine has many advantages such as low investment costs, low emissions and a low water consumption. This fact allows its application in many power engineering systems, for example as parts of gas and oil transport systems. It is possible to increase the efficiency of gas turbines through the use of combined cycles. For this purpose, the steam cycle is used most frequently. These systems are highly efficient in terms of energy, but they are very complex and have a high water consumption. An alternative to steam cycles are gas-air systems, referred to as the ABC’s (Air Bottoming Cycles), which use hot combustion gases as a heat source for the air cycle. ABC’s are composed of a gas turbine powered by natural gas, an air compressor and an air turbine coupled to the system by means of a heat exchanger, referred to as the AHX (Air Heat Exchanger).
The paper presents an application of gas-air systems with example configurations, together with thermodynamic characteristics. Two technological structures are taken into consideration — a simple system of the ABC and an ABC with air intercooling. A parametric analysis of these systems is performed using a special computer program with real gas properties for enthalpy and entropy calculations. A basic comparative analysis of gas turbine air bottoming cycle and combined gas-steam cycle has been also done. Other important calculations are related to the heat exchanger, which is one of the most important components in this system because it couples the gas and air parts. The efficiency of the whole cycle depends on a rationally designed heat exchanger. The calculations are performed for a shell-and-tube exchanger, as well as for a plate heat exchanger. For all investigations an purchase cost of machines and devices is also determined.
Numerical Simulation for the Preliminary Design of Fuel Flexible Stationary Gas Turbine Combustors Using Conventional and Alternative Fuels
Authors: Irrazabal Bohorquez Washington Orlando , Barbosa João Roberto , Bastiaans Rob Johan Maria , de Goey Philip 
Published: July 2013

Currently, high efficiency and low emissions are most important requisites for the design of modern gas turbines due to the strong environmental restrictions around the world. In the past years, alternative fuels have been considered for application in industrial gas turbines. Therefore, combustor performance, pollutant emissions and the ability to burn several fuels became of much concern and high priority has been given to the combustor design.
This paper describes a methodology focused on the design of stationary gas turbines combustion chambers with the ability to efficiently burn conventional and alternative fuels. A simplified methodology is used for the calculations of the equilibrium temperature and chemical species in the primary zone of a gas turbine combustor. Direct fuel injection and diffusion flames, together with numerical methods like Newton-Raphson, LU Factorization and Lagrange Polynomials, are used for the calculations. Diesel, ethanol and methanol fuels were chosen for the numerical study.
A computer code sequentially calculates the main geometry of the combustor. From the numerical simulation it is concluded that the basic gas turbine combustor geometry, for some operating conditions and burning diesel, ethanol or methanol, are of similar sizes, because the development of aerodynamic characteristics predominate over the thermochemical properties.
It is worth to note that the type of fuel has a marked effect on the stability and combustion advancement in the combustor. This can be seen when the primary zone is analyzed under a steady-state operating condition. At full power, the pressure is 1.8 MPa and the temperature 1,000 K at the combustor inlet. Then, the equivalence ratios in the primary zone are 1.3933 (diesel), 1.4352 (ethanol) and 1.3977 (methanol) and the equilibrium temperatures for the same operating conditions are 2,809 K (diesel), 2,754 K (ethanol) and 2,702 K (methanol). This means that the combustor can reach similar flame stability conditions, whereas the combustion efficiency will require richer fuel/air mixtures of ethanol or methanol are burnt instead of diesel.
Another important result from the numerical study is that the concentration of the main pollutants (CO, CO2, NO, NO2) is reduced when ethanol or methanol are burnt, in place of diesel.
Discussion of Some Myths/Features Associated With Gas Turbine Inlet Fogging and Wet Compression
Authors: Wang Ting , Khan Jobaidur R. 
Published: July 2013

Gas turbine inlet fogging and overspray (high-fogging) have been considered the most cost-effective means of boosting a gas turbine’s total power output, especially under hot or dry weather conditions. The result of employing fogging or overspray is indisputably clear — total power output is increased; however, development of the theory and explanation of the phenomena associated with fogging and overspray are not always consistent and are sometimes misleading and incorrect. This paper focuses on reviewing several interesting features and commonly discussed topics, including (a) entropy production of water evaporation, (b) the effect of centrifugal force on water droplets, and (c) whether water droplets can survive the journey in the compressor and enter the combustor. Furthermore, three turbine myths: that fogging/overspray increases the air density in the compressor, reduces the compressor power consumption, and noticeably enhances the gas turbine efficiency, are examined and discussed.
Some common mistakes in describing the compressor work are identified and corrected. A newly constructed multiphase T-S diagram is used to explain the physics of water droplet evaporation process and corresponding entropy production during wet compression.
Helicopter-based laser scanning: a method for quantitative analysis of large-scale sedimentary architecture
Authors: Rittersbacher Andreas , Buckley Simon J. , Howell John A. , Hampson Gary J. , Vallet Julien 
Published: July 2013

Abstract
Studies of large-scale sedimentary architecture are mainly based on the interpretation of two-dimensional photomosaics. This method cannot account for the natural rugosity of outcrop exposures, introducing errors in the measurement of geobody sizes and orientations. In the past, three-dimensional outcrop studies have relied on time-intensive fieldwork, with irregular sampling and low geometric accuracy. More recently, terrestrial laser scanning, or LiDAR (Light Detection and Ranging), has been widely applied to small-scale outcrops, but range and accessibility preclude its usage on larger-scale outcrops. Oblique helicopter-based laser scanning, however, allows the collection of tens of kilometres of outcrop sections in a relatively short time frame. In this paper, a procedure for collecting and processing such virtual outcrop data is outlined, and the application of the technique for extracting dimensions of fluvial geobodies from two large and otherwise inaccessible outcrops from Utah is presented. The results are compared to interpretations from more conventional photomosaicking of the same outcrops. Results show that the use of helicopter-based laser scanning enables geoscientists to rapidly acquire georeferenced data that can then be used for sedimentological interpretation and analysis on reservoir scales. It is concluded that helicopter-based laser scanning promotes sedimentological research and is well suited to capturing quantitative geometrical data from large outcrops.