bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local variation in plant quality influences large‐scale population dynamics
Authors: Riolo Maria A. , Rohani Pejman , Hunter Mark D. 
Published: February 2015

Spatial variation in ecological systems can arise both as a consequence of variation in the quality and availability of resources and as an emergent property of spatially structured interactions. We used a spatially explicit model to simulate populations of herbivore hosts and their parasitoids in landscapes with different levels of variance in plant patch quality and different spatial arrangements of high‐ and low‐quality plant patches.We found that even small variation in patch quality at a fine spatial scale decreased overall herbivore populations, as parasitoid populations on low‐quality plant patches were subsidized by those from high‐quality neighbors. On landscapes with large, homogeneous regions of high‐ and low‐quality plant patches, herbivore populations increased with variation in patch quality.Overall, our results demonstrate that local variation in resource quality profoundly influences global population dynamics. In particular, fine‐scale variation in plant patch quality enhanced biological control of herbivores by parasitoids, suggesting that adding back plant genetic variation into perennial production systems may enhance the biological control of herbivores by their natural enemies.
Correlation of Scar in Cardiac MRI and High‐Resolution Contact Mapping of Left Ventricle in a Chronic Infarct Model
Authors: THAJUDEEN ANEES , JACKMAN WARREN M. , STEWART BRIAN , COKIC IVAN , NAKAGAWA HIROSHI , SHEHATA MICHAEL , AMORN ALLEN M. , KALI AVINASH , LIU EZH , HARLEV DORON , BENNETT NATHAN , DHARMAKUMAR ROHAN , CHUGH SUMEET S. , WANG XUNZHANG 
Published: February 2015

BackgroundEndocardial mapping for scars and abnormal electrograms forms the most essential component of ventricular tachycardia ablation. The utility of ultra‐high resolution mapping of ventricular scar was assessed using a multielectrode contact mapping system in a chronic canine infarct model.MethodsChronic infarcts were created in five anesthetized dogs by ligating the left anterior descending coronary artery. Late gadolinium‐enhanced magnetic resonance imaging (LGE MRI) was obtained 4.9 ± 0.9 months after infarction, with three‐dimensional (3D) gadolinium enhancement signal intensity maps at 1‐mm and 5‐mm depths from the endocardium. Ultra‐high resolution electroanatomical maps were created using a novel mapping system (Rhythmia Mapping System, Rhythmia Medical/Boston Scientific, Marlborough, MA, USA) Rhythmia Medical, Boston Scientific, Marlborough, MA, USA with an 8.5F catheter with mini‐basket electrode array (64 tiny electrodes, 2.5‐mm spacing, center‐to‐center).ResultsThe maps contained 7,754 ± 1,960 electrograms per animal with a mean resolution of 2.8 ± 0.6 mm. Low bipolar voltage (<2 mV) correlated closely with scar on the LGE MRI and the 3D signal intensity map (1‐mm depth). The scar areas between the MRI signal intensity map and electroanatomic map matched at 87.7% of sites. Bipolar and unipolar voltages, compared in 592 electrograms from four MRI‐defined scar types (endocardial scar, epicardial scar, mottled transmural scar, and dense transmural scar) as well as normal tissue, were significantly different. A unipolar voltage of <13 mV correlated with transmural extension of scar in MRI. Electrograms exhibiting isolated late potentials (ILPs) were manually annotated and ILP maps were created showing ILP location and timing. ILPs were identified in 203 ± 159 electrograms per dog (within low‐voltage areas) and ILP maps showed gradation in timing of ILPs at different locations in the scar.ConclusionsUltra‐high resolution contact electroanatomical mapping accurately localizes ventricular scar and abnormal myocardial tissue in this chronic canine infarct model. The high fidelity electrograms provided clear identification of the very low amplitude ILPs within the scar tissue and has the potential to quickly identify targets for ablation.
Better innovate than compromise: A novel hepatic outflow reconstruction technique in pediatric living donor liver transplantation
Authors: Cherian P. Thomas , Mishra Ashish K. , Bangaari Ashish , Kota Venugopal , Sathyanarayanan Mohan , Raya Ravichandra , Rela Mohamed 
Published: February 2015

AbstractPediatric LDLT using donors with unfavorable vascular anatomy is challenging in terms of donor safety, and complexity of reconstruction in the recipient. We describe an innovative technique of hepatic venous outflow reconstruction involving the recipient RHV, in the presence of a rudimentary RHV in the donor. The postoperative course of the donor and recipient was uneventful with satisfactory venous outflow in both. This technique avoided the use of prosthetic material, an important consideration given the recipient age and requirement for growth. This shows that donors previously considered unsuitable for donation can be utilized safely as long as principles of vascular anastomosis are adhered to. Moreover, it highlights that innovation is sometimes necessary to avoid compromise in donor safety.
Late Recognition of Unintended Pregnancies
Authors: Ayoola Adejoke B. 
Published: February 2015

AbstractObjectiveLate recognition of pregnancy and unintended pregnancy has been associated with adverse pregnancy outcomes such as preterm birth, low birth weight, and admission to neonatal care. This study examined the factors associated with late recognition of pregnancy among women reporting unintended pregnancy.Design and SampleA secondary analysis of a population‐based survey, the Pregnancy Risk Assessment Monitoring System of the United States. A total of 143,303 women of childbearing age. Analyses included descriptive statistics and multivariate analysis using logistic regression.ResultsExactly, 42.4% described their pregnancies as unintended and 28.3% recognized their pregnancies late. Women with unintended pregnancy took longer, 7.2 weeks (99% CI = 7.07–7.24) to recognize their pregnancies compared to 5.2 weeks (99% CI = 5.18–5.27) for women with intended pregnancy. Late recognition of pregnancy was significantly higher among women who were not married (adjusted odds ratio [AOR] = 1.29, p < .01), had more arguments with their partners (AOR = 1.08, p < .01), were smokers (AOR = 1.15, p < .01), and belonged to an ethnic minority group.ConclusionsPublic health nurses and other health professionals can promote early recognition of pregnancy among women who are not married, belong to ethnic minority groups, or have more arguments with their husbands or partners.
Fatigue reduces the complexity of knee extensor torque fluctuations during maximal and submaximal intermittent isometric contractions in man
Authors: Pethick Jamie , Winter Samantha L. , Burnley Mark 
Published: February 2015

Key points
Healthy physiological systems generate time series possessing complex structures, as seen for example in heart rate variability, respiratory rate and gait.
A loss of complexity in physiological time series has been associated with system dysfunction, and this loss is a characteristic feature of torque output from the ageing neuromuscular system.
We sought to determine the effect of neuromuscular fatigue on the complexity of knee extensor torque output in healthy young humans performing repeated maximal and submaximal contractions.
Fatigue resulted in a substantial loss of knee extensor torque complexity, with the noise in the torque signal becoming increasingly Brownian in character.
Complexity has been associated with system adaptability, and the fatigue‐induced loss of complexity, the physiological origin of which is obscure, may contribute to the inability to sustain physical exercise.
AbstractNeuromuscular fatigue increases the amplitude of fluctuations in torque output during isometric contractions, but the effect of fatigue on the temporal structure, or complexity, of these fluctuations is not known. We hypothesised that fatigue would result in a loss of temporal complexity and a change in fractal scaling of the torque signal during isometric knee extensor exercise. Eleven healthy participants performed a maximal test (5 min of intermittent maximal voluntary contractions, MVCs), and a submaximal test (contractions at a target of 40% MVC performed until task failure), each with a 60% duty factor (6 s contraction, 4 s rest). Torque and surface EMG signals were sampled continuously. Complexity and fractal scaling of torque were quantified by calculating approximate entropy (ApEn), sample entropy (SampEn) and the detrended fluctuation analysis (DFA) scaling exponent α. Fresh submaximal contractions were more complex than maximal contractions (mean ± SEM, submaximal vs. maximal: ApEn 0.65 ± 0.09 vs. 0.15 ± 0.02; SampEn 0.62 ± 0.09 vs. 0.14 ± 0.02; DFA α 1.35 ± 0.04 vs. 1.55 ± 0.03; all P < 0.005). Fatigue reduced the complexity of submaximal contractions (ApEn to 0.24 ± 0.05; SampEn to 0.22 ± 0.04; DFA α to 1.55 ± 0.03; all P < 0.005) and maximal contractions (ApEn to 0.10 ± 0.02; SampEn to 0.10 ± 0.02; DFA α to 1.63 ± 0.02; all P < 0.01). This loss of complexity and shift towards Brownian‐like noise suggests that as well as reducing the capacity to produce torque, fatigue reduces the neuromuscular system's adaptability to external perturbations.
2MW Class High Efficiency Gas Turbine IM270 for Co-Generation Plants
Authors: Kobayashi Hideo , Tsugumi Shogo , Yonezawa Yoshio , Imamura Riuzou 
Published: February 2015

IHI is developing a new heavy duty gas turbine engine for 2MW class co-generation plants, which is called IM270. This engine is a simple cycle and single-spool gas turbine engine. Target thermal efficiency is the higher level in the same class engines. A dry low NOx combustion system has been developed to clear the strictest emission regulation in Japan. All parts of the IM270 are designed with long life for low maintenance cost. It is planned that the IM270 will be applied to a dual fluid system, emergency generation plant, machine drive engine and so on, as shown in Fig.1.
The development program of IM270 for the co-generation plant is progress. The first prototype engine test has been started. It has been confirmed that the mechanical design and the dry low NOx system are practical. The component tuning test is being executed. On the other hand, the component test is concurrently in progress. The first production engine is being manufactured to execute the endurance test using a co-generation plant at the IHI Kure factory.
This paper provides the conceptual design and status of the IM270 basic engine development program.
Design and Development of a Landfill Gas Combustion System for the Typhoon Gas Turbine
Authors: Ecob David J. , Boyns Michael B. , Walsh Steve , McClave Ken , Hunt A. Allen 
Published: February 2015

This paper presents design, initial combustion development testing and engine validation results of a combustion system which is capable of burning a medium CV landfill gas or conventional diesel oil in a 5MW gas turbine.
Initial rig testing of the original combustion system burning a simulated medium CV gas revealed stability problems and inherently poor combustion efficiencies.
A study of primary zone flow patterns and fuel placement led to the conclusion that the problems were due to axial injection of the gas. Subsequently a modified dual fuel injector was designed which relied on swirled instead of axial injection. The modified injector design also embodies a passive purge feature, which uses combustor wall pressure drop to feed air directly into the gas swirler passages. This prevents ingestion of harmful combustion products when running on diesel oil.
Extensive rig testing demonstrated encouraging combustion efficiencies and emissions using 40% and 54% methane landfill gas compositions across a simulated engine load profile. Operation of the modified injector on diesel oil however, demonstrated a need for the incorporation of an anti-carbon feature. The effectiveness of this anti-carbon modification was verified as part of a ‘validation engine cycle’ simulating the actual engine operating procedure from light up to shutdown. Post test inspection revealed carbon deposition to be significantly reduced. Combustion efficiencies, emissions, traverse quality, metal temperatures, stability and noise were all found to be satisfactory.
Numerical Investigation of the Clocking Effects in a Multistage Turbine
Authors: Eulitz Frank , Engel Karl , Gebing Hermann 
Published: February 2015

The paper presents a numerical study on turbine clocking using a stator/rotor/stator model configuration of equal pitches. The results of time accurate flow calculations for four clocking positions are compared. The unsteady, two dimensional Reynolds averaged equations are solved using a one-equation turbulence model by Spalart and Allmaras. In absence of a transition model, the flow is assumed to be fully turbulent.
In a first analysis of the unsteady data, emphasis has been put on the loss production of the clocked stator. A Fourier decomposition of the specific entropy at the stator entry and exit is discussed. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for a given rotor speed. Further, clocking has little upstream influence.
NOx Control in Black Liquor Fuel Gas Combined Cycles
Authors: Sliger Rebecca N. , Berz Marcel D. , Kramlich John C. , Malte Philip C. 
Published: February 2015

The gasification of black liquor, followed by its use in gas turbine engines, is an emerging alternative to the direct firing of the liquor in Tomlinson recovery boilers. Many gasification systems, however, convert the fuel nitrogen present in the liquor into ammonia (NH3) in the fuel gas, which leads to unacceptable NOx emissions in gas turbine combustors.
This work uses detailed chemical kinetic modeling to examine the influence of two combustor modifications for the control of NOx emissions from black liquor fuel gas combustion. Availability analysis is also used to evaluate the influence of these NOx control choices on the thermodynamic architecture of the overall system. A rich-quench-lean configuration makes use of air staging. An alternative is to use a hot, rich external precombustor to remove NH3 before the main combustor. Here, the external, rich stage operates at around 30% theoretical air. Adiabatic temperatures are too low to obtain good NH3 reduction, so recuperative heating is necessary.
A Study of the Behaviour of Flow in a Diagonal-Flow Turbomachine
Authors: Ray Arjun Sarathi 
Published: February 2015

Experiments were conducted on a diagonal-flow machine to study the behaviour of flow. Measurements showed that at reduced flow rates, reversal of flow occurs near the tip upstream of the rotor and near the hub downstream. At high flow rates, the flow reverses near tip at downstream only. In fact, there is only a limited regime of operation where the flow is not reversed before or after the impeller. The best fluid-dynamic efficiency was observed to be midway of this non-reversed flow regime.
Through-flow solutions of the mean hub-to-tip streamsurface were carried out by streamline curvature computation and compared with experimental results. The comparison showed good agreement of the predicted values with the experimental data. However, attempts to compare theoretical estimates of rotor losses with experimental measurements showed that the existing loss models are inadequate for loss prediction and further work is required in this direction.
The head-flow characteristic of the machine showed a droop at reduced flow rates, typical of what one usually notices in an axial-flow machine with the onset of blade stall. Study of the time history of velocity downstream of rotor illustrated that unlike rotating ‘stall-cells’ in axial-flow machines, the blade stall in the present case did not possess any regular pattern nor any unique speed of propagation. Near the hub at downstream of rotor, where the flow finally reverses upon reduction of flow rate, the stall appeared as patches of ‘blockage’ type disturbance over an otherwise systematic train of blade wakes when the flow coefficient reaches a value where the droop in the characteristic curve starts.
Modelling of the Tip Clearance Losses in Axial Flow Machines
Authors: Nikolos I. K. , Douvikas D. I. , Papailiou K. D. 
Published: February 2015

The possibility of predicting the total pressure loss radial distribution, due to the tip clearance presence, is examined in this paper. Models advanced for the diffusion of a line vortex are used for the simulation of the leakage vortex induced velocity and pressure fields, with sufficient success. The leakage vortex strength seems to control directly only a small part of the total pressure loss distribution, the one connected with the pressure deficit and the rotating flow. The remaining profiles result as functions of a free parameter — the constant of integration — and an assumption is needed to close the problem. The widely proposed observation for lost secondary jet kinetic energy is considered as a method of predicting the total amount of tip clearance loss in successive planes inside and downstream the blade passage.
A calculation procedure for predicting the tip clearance effects in the flow field inside and downstream the tip clearance, has been developed. The method, being compatible with a meridional flow calculation procedure, accounts for the calculation of the peripherally mean deficit profiles of the various flow quantities. The predictive capability of the calculation procedure is established in a wide range of test cases, including axial flow compressor cascades, isolated rotors and multi-row machines. The radial variation of tip clearance pressure loss is calculated with sufficient accuracy for engineering purposes.
Experimental Investigation of a Single Stage Axial Flow Compressor With Controlled Diffusion Airfoils
Authors: Pieper S. , Schulte J. , Hoynacki A. , Gallus H. E. 
Published: February 2015

In order to verify an inverse design concept for modern compressor bladings, a subsonic compressor front stage with IGV was investigated.
One objective of the design was to survey the flow field in detail, with emphasis on 3D viscous and unsteady aspects of the flow. Therefore, the compressor was equipped with various steady and unsteady measurement techniques. Additionally, a compressor design was chosen that allows an extension up to three stages with regard to the investigation of multistage axial compressor flow behavior.
Test results of the steady measurements are discussed for IGV, rotor, and stator flow at design conditions as well as the overall stage performance. The measurements of the steady flow behavior confirm the expected design performance and show the high potential of the controlled diffusion airfoil concept. Only at the side walls near hub and casing there are some differences between design and measurement due to the complex three dimensional flow.
For the study of unsteady effects, detailed measurements using hot-wire probes, glue-on hot-films, and semiconductor pressure transducers were performed. All measurements are evaluated using the ensemble-average technique. The results show how the boundary layers of the inlet guide vanes and stator blades develop in a flow that is periodically disturbed by the rotor. Time-dependent pressure distributions at midspan of both stators are described. In addition, the unsteady pressure field at the casing above the rotor was investigated. The minimum wall pressure is located away from the blade suction surface. The effects of tip clearance flow on the performance are presented. The radial extent covers 15% span from the tip. At rotor exit, the unsteady pressure field and the time-dependent three-dimensional velocity vectors illustrate the salient features of the viscous flow associated with the rotor.
Development of Gas Turbine for Air-Blown Gasification
Authors: Wada K. , Sasada T. , Hayashi H. 
Published: February 2015

The development progress and operation results with the gas turbine developed for the first coal gasification pilot plant (200T/D) in Japan are reported hereafter.
The gas turbine based on the scale down of the commercial machine (H25), is called H14. To deal with coal gasification, the development of the combustor is main subject because of the low caloric value of fuel. We developed the combustor through many combustion tests with simulation gas, and the selected combustor was supplied to the actual gas test at the pilot plant. We could grasp the limit of stable combustion of the combustor because the fuel characteristics of actual fluctuated sharply. In addition, we could experience phenomena peculiar to the gasification such as the back fire problem and finally succeeded in air extraction linkage operation by no means inferior to the used coal fired thermal power generation. Thus we established the gas turbine technology for coal gasification and opened a way to future large gasification plants.
Adaptability of the Solar Advanced Turbine Systems to Biomass and Coal Derived Fuels
Authors: White David J. , LeCren Richard T. , Wen Chaur S. 
Published: February 2015

SolarTurbines Incorporated (Solar) is developing the technologies that are to be used for a highly efficient, recuperated, Advanced Turbine System (ATS) that is aimed at the dispersed power generation market. With ultra-low-emissions in mind the primary fuel selected for this gas turbine engine system is natural gas. Although this gas fired ATS (GFATS) will primarily employ natural gas, the use of other fuels, particularly those derived from coal and renewable resources cannot be overlooked. The enabting technologies necessary to direct-fire coal in gas turbines were developed during the 1980s. This Solar development, co-sponsored by the U.S. Department of Energy (DOE), resulted in the testing of a full size coal-water-slurry fired combustion system. In parallel with this program the DOE funded the development of integrated gasification combined-cycle systems (IGCC). This report describes the limitations of the Solar ATS (recuperated engine) and how these limitations lead to a recommended series of modifications that will allow the use of these alternative fuels.
Three approaches have been considered: direct-fired combustion using either a slagging combustor, or a pressurized fluidized bed (PFBC), externally or indirectly fired approaches using pulverized fuel, and external gasification of the fuel with subsequent direct combustion of the secondary fuel. Each of these approaches requires substantial hardware and system modifications for efficient fuel utilization. The integration issues are discussed in the sections below and a recommended approach for gasification is presented.
Friction Damping of Hollow Airfoils: Part I — Theoretical Development
Authors: Griffin J. H. , Wu W.-T. , El-Aini Y. 
Published: February 2015

The quest for higher performance engines in conjunction with the requirement for lower life cycle costs has resulted in stage configurations that are more susceptible to high cycle fatigue. One solution is the use of innovative approaches that introduce additional mechanical damping. The present paper describes an approach that may be used to assess the benefits of friction dampers located within internal cavities of a hollow structure.
The friction dampers used in this application are often relatively thin devices that, if unconstrained, have natural frequencies in the same range as the natural frequencies of the hollow airfoil. Consequently, the analytical approach that is developed is distinct in that it has to take into account the dynamic response of the damper and how it changes as the amplitude of the vibration increases. In this paper, results from the analytical model are compared with independently generated results from a time integration solution of a three mass test problem. Results from the analytical model are compared with experimental data in a companion paper.