bluuebunny/crossref_metadata_2025 huggingface dataset:
Unexpected MH deaths without exposure to inhalation anesthetics in pediatric patients
Authors: Brandom Barbara W. , Muldoon Sheila M.
Published: July 2013

Children, later found to have ryanodine receptor type one variants (RYR1), died without exposure to inhalation anesthetics. Family members with the same RYR1 variants had contracture tests consistent with susceptibility to malignant hyperthermia or in vitro testing showed increased sensitivity to RYR1 agonist.
Estimation of Daily Ultraviolet Radiation in Beijing Using a Semiempirical Method
Authors: Zhang Xinghua , Hu Bo , Wang Yuesi
Published: July 2013

This study proposes a semiempirical method to reconstruct daily ultraviolet (UV) radiation from global solar (G) radiation measurements using a radiative transfer model. The attenuation ratio and cloud modification factors are calculated based on measured and simulated data under cloudless‐sky conditions. A reconstruction method ofUVradiation is established using cloud modification factors; based on comparisons among reconstructions and measurements, the reconstruction model is demonstrated to offer high resolution. The bias errors for daily measured and reconstructedUVradiation are maintained within ±20%, the mean absolute bias error (mabe) is 7.7% and the root mean square error (rmse) is 9.7%. Furthermore, the model performance and transferability were tested by comparison with a simple empirical model in Beijing, Eerduosi and Hailun. A comparison of the measured and estimatedUVvalues for the two methods in the aforementioned three locations revealed that smaller mabe and rmse were observed in our method, with both of these values in the three locations being less than 14%. Thus, a better applicability and transferability has been confirmed. The results and analysis should contribute to improving the knowledge about actualUVclimate characteristics.
Doping of TiO2–GO and TiO2–rGO with Noble Metals: Synthesis, Characterization and Photocatalytic Performance for Azo Dye Discoloration
Authors: Štengl Václav , Henych Jiří , Vomáčka Petr , Slušná Michaela
Published: July 2013

The nanocomposites of titania coupled with graphene oxide (GO) and reduced graphene oxide (rGO), respectively, were prepared by homogeneous hydrolysis with urea. Graphene was obtained by effect of high‐intensity cavitation field on natural graphite in the presence of strong aprotic solvents in pressurized ultrasonic reactor. The morphology of TiO2–GO and TiO2–rGO composites was assessed by scanning electron microscopy and atomic force microscopy. The nitrogen adsorption–desorption was used for determination of surface area (BET) and porosity. Raman and IR spectroscopy were used for qualitative analysis and diffuse reflectance spectroscopy was employed to estimate band‐gap energies. Further enhancement of the photocatalytic activity was attained by codoping of composites with noble metals—Au, Pd and Pt. The photocatalytic activity of TiO2–GO and TiO2–rGO were assessed by photocatalytic decomposition of Orange II dye in an aqueous slurry under UV and visible light irradiation. The photocatalytic activity of noble metals codoped samples was determined with decomposition of Reactive Black 5 azo dye.
Causes and consequences of intra‐ and inter‐host heterogeneity in defence against nematodes
Authors: Hayward A. D.
Published: July 2013

Despite strong natural and artificial selection for increased resistance to nematode parasites, there is considerable heterogeneity between hosts in human, livestock and wildlife populations, with a minority of hosts carrying the majority of parasites. In addition, levels of defence may vary across the lifespan of individuals due to changes in their physiological state and infection history. Such variation influences nematode transmission dynamics and the evolution of parasite life‐history strategies. Therefore, identifying sources of between‐ and within‐individual variation in resistance and predicting their consequences is crucial for understanding the epidemiology of nematode parasitic diseases. In this review, several key sources of variation are identified, using examples from mouse models, immuno‐epidemiological studies of human populations and observational and experimental studies of wildlife and livestock. The mutual applicability of approaches used across these study systems is emphasized, with the assertion that the concerted efforts of researchers from a range of disciplines will enable us to better understand the proximate and ultimate causes of variation in defence against nematode parasites. This will facilitate predictions of the epidemiological and evolutionary consequences of this variation, with the potential to improve disease treatment and management.
Differences in Retail Inventory Investment Behavior During Macroeconomic Shocks: Role of Service Level
Authors: Kesavan Saravanan , Kushwaha Tarun
Published: July 2013

In this article, we analyze how retailers change their inventory investment behavior in response to macroeconomic shocks. We examine if service level, as measured by the ratio of stockout to inventory holding costs, can explain the differences in observed behavior across retailers. We use data on macroeconomic indicators and quarterly filings of US public retailers from 1985 to 2009 to estimate a dynamic model of short‐ and long‐term impact of macroeconomic shocks on inventory investment. Our results show that retailers with a high service level increase their inventory investment significantly more than those with a low service level during expansion shocks. Conversely, retailers with a low service level curtail their inventory investment significantly more than those with a high service level during periods of economic contractions. Thus, we show that the aggregate change in inventory investment documented in prior macroeconomics research is driven by different sets of retailers, as predicted by newsvendor logic. We draw implications of our findings to retailers as well as their suppliers.
“Womb for Rent”: International Service Trade Employing Assisted Reproduction Technologies (ARTs)
Authors: Pelzman Joseph
Published: July 2013

Infertility affects approximately 2–3 million married couples in the USA and a larger cohort of unmarried men and women. For those not inclined to adopt, science has provided another option, one based on assisted reproduction through artificial insemination, commonly known as in vitro fertilization (IVF). Under this framework a woman, designated as a “surrogate”, bears a baby on behalf of the intended parents with the objective of relinquishing her rights to the child after birth. The subcontract for the services of a “surrogate” or more specifically for the use of her “womb” can be viewed as part of the literature on outsourcing of production by a vertically integrated family. The lack of universal enforcement of “surrogacy” contracts in the USA creates a demand for outsourcing of surrogacy services. One beneficiary of this uncertainty in enforcement is India which provides gestational services to intended international parents.
Trade, Skill Biased Technical Change and Wage Inequality in South Africa
Authors: Rattsø Jørn , Stokke Hildegunn E.
Published: July 2013

Trade openness influences the wage structure via technology adoption in middle income countries. Given the econometric challenges of handling endogenous trade and technology interaction, we offer an alternative quantification based on calibration of a general equilibrium model. We expand the standard open economy Ramsey model to include comparative advantage, technology adoption and skill bias influenced by investment decisions. The calibration constructs a reference path for South Africa and allows counterfactual analysis of trade openness. The quantitative results imply that trade effects via technology adoption and skill bias can be an important determinant of wage inequality in middle income countries.
Supermodularity and Global Supply Chains without the South
Authors: Ngienthi Wanida , Ma Yan , Dei Fumio
Published: July 2013

We investigate why the South is hardly involved in the global supply chain for the Boeing 787. We demonstrate that if the production process is supermodular, the South is excluded from global supply chains.
Thermal Effects During Tensile Deformation of Ti‐6Al‐4V at Different Strain Rates
Authors: Galán J. , Verleysen P. , Degrieck J.
Published: July 2013

An in‐depth analysis of the effect of heat generated by plastic work on the observed tensile behaviour of Ti­6Al­4V at different strain rates is presented. Special emphasis is put on the transition from isothermal to adiabatic conditions and how this transition is affected by several process parameters such as material properties, environmental conditions and sample geometry. Experiments are performed in isothermal conditions at moderate temperatures, from −10 to 70 °C, as well as at strain rates from quasi‐static speeds to more than 1000 s−1 using a split Hopkinson tensile bar setup. This experimental data is used in conjunction with numerical simulations to determine the evolution of temperature during the experiments and the temperature and strain rate sensitivity of the material, as well as the Taylor–Quinney coefficient. Finally, a full model of the material behaviour is presented and used to define clear limits for adiabatic and isothermal conditions.
La santé des pasteurs mobiles auSahel – Bilan de 15 années de recherches et développement
Authors: Montavon A. , Jean‐Richard V. , Bechir M. , Daugla D. M. , Abdoulaye M. , Bongo Naré R. N. , Diguimbaye‐Djaibé C. , Alfaroukh I. O. , Schelling E. , Wyss K. , Tanner M. , Zinsstag J.
Published: July 2013

Dans leSahel, entre laMauritanie et laSomalie incluant leNordKenya, environ 20 à 30 millions de personnes vivent en transhumance. Le rythme de leur migration suit l’évolution saisonnière du climat et la disponibilité des ressources, telle que l'eau, le pâturage et le sel. Malgré une exposition élevée à certaines maladies comme les zoonoses et les problèmes conditionnés liés au climat, les pasteurs mobiles sont parmi les populations quasiment exclues du système de santé, car la mise à disposition des services sociaux adaptés à un mode de vie mobile est difficile. Suivant l'objectif de recherche d'un meilleur accès aux soins des pasteurs mobiles, l'InstitutTropical et deSantéPubliqueSuisse, en partenariat avec plusieurs institutions dans la région, est actif au Sahel depuis 15 ans, aussi bien dans le domaine de la recherche, que celui des actions de développement. Basées sur une approche orientée vers les besoins des pasteurs mobiles pour leur développement, des recherches interdisciplinaires ont contribué à mieux comprendre la situation et les problèmes des éleveurs. En relation de la proximité entre l'homme et son bétail, une approche unissant la santé humaine et animale s'est avérée bonne et la valeur ajoutée d'une meilleure collaboration entre médecine humaine, animale et l'environnement a été démontrée. Ces approches utiles devraient être poursuivies et consolidées dans les recherches et le développement des actions futurs.
Anaphylaxis in dogs and cats
Authors: Shmuel Daniella L. , Cortes Yonaira
Published: July 2013

Objective

To review and summarize current information regarding the pathophysiology and clinical manifestations associated with anaphylaxis in dogs and cats. The etiology, diagnosis, treatment, and prognosis is discussed.

Etiology

Anaphylaxis is a systemic, type I hypersensitivity reaction that often has fatal consequences. Many of the principal clinical manifestations involve organs where mast cell concentrations are highest: the skin, the lungs, and the gastrointestinal tract. Histamine and other deleterious inflammatory mediators promote vascular permeability and smooth muscle contraction; they are readily released from sensitized mast cells and basophils challenged with antigen. Anaphylaxis may be triggered by a variety of antigens including insect and reptile venom, a variety of drugs, vaccines, and food.

Diagnosis

Anaphylaxis is a clinical diagnosis made from a collection of signs and symptoms. It is most commonly based on pattern recognition. Differential diagnoses include severe asthma, pheocromocytoma, and mastocytosis.

Therapy

Epinephrine is considered the drug of choice for the treatment of anaphylaxis. It acts primarily as a vasopressor in improving hemodynamic recovery. Adjunctive treatments include fluid therapy, H1and H2antihistamines, corticosteroids, and bronchodilators; however, these do not substitute for epinephrine.

Prognosis

Prognosis depends on the severity of the clinical signs. The clinical signs will vary among species and route of exposure. The most severe clinical reactions are associated when the antigen is administered parenterally.
Mechanical ventilation in a dog with acetylcholinesterase inhibitor toxicosis
Authors: Tse Yuki C. , Sharp Claire R. , Evans Timothy
Published: July 2013

Background

To describe a case of acetylcholinesterase inhibitor (AChEI) toxicosis with ventilatory failure that was successfully treated with mechanical ventilation (MV).

Key Findings

A 7‐year‐old, female spayed German Short‐haired Pointer, presented with acute onset ptyalism, generalized muscle tremors, and diarrhea. Physical examination findings included evidence of muscarinic overstimulation in the parasympathetic nervous system (eg, diarrhea, ptyalism, lacrimation), and nicotinic overstimulation in the sympathetic nervous system (tachycardia), central nervous system (agitation), and the neuromuscular junction (eg, diffuse muscle fasciculations, tetraparesis). Point‐of‐care testing demonstrated hyperlactatemic metabolic acidosis and respiratory acidosis (hypoventilation). Hypoventilation progressed to respiratory failure and the dog lost its gag reflex necessitating emergency endotracheal intubation and MV. Additional treatments included atropine, parenteral antimicrobials (for aspiration pneumonia), pralidoxime, and supportive care. Weaning from the ventilator was achieved in 4 days. The dog was administered supplemental oxygen for 24 hours, and discharged 48 hours later with improved neurologic function and normal respiratory drive. Whole blood acetylcholinesterase activities measured on day 0, 2, and 4 and were consistent with AChEI toxicity.

New or Unique Information Provided

Specific AChEI toxicity (ie, carbamate and organophosphate) has been reported in the veterinary literature with good prognosis for survival and hospital discharge. While the existing veterinary literature suggests that ventilatory failure is rare in this disease syndrome, consideration for treatment with MV must be made for patients that develop respiratory failure (associated with hypoventilation, bronchoconstriction, bronchorrhea, or aspiration pneumonia).
Adjunctive therapy with intravenous lipid emulsion and methocarbamol for permethrin toxicity in 2 cats
Authors: Kuo Kendon , Odunayo Adesola
Published: July 2013

Objective

To describe the use of an intravenous lipid emulsion (ILE) as an adjunctive therapy in 2 cats with permethrin toxicity.

Case Series Summary

Two cats that presented with severe permethrin toxicity were treated withILEas part of their treatment regimens. Both cats improved dramatically following therapy with decontamination,ILE, methocarbamol, and supportive care.

New or Unique Information Provided

This is the first reported use ofILEas an adjunctive treatment for cats with permethrin toxicity. Outcome was favorable in both cats and no adverse effects were noted from theILE.
Can the riparian invader, Arundo donax, benefit from clonal integration?
Authors: Kui L , Li F , Moore G , West J
Published: July 2013

Resource sharing through rhizomes of clonal plants supplements locally available nutrients to enhance recruitment and growth in resource‐limited environments. We investigated whether Arundo donax, an invasive clonal plant, can benefit from clonal integration. Sharing resources between ramets can facilitate resprouting from mowing, fire and herbicide treatments, but it is unknown whether clonal integration contributes to A. donax invasion success. Our first objective was to determine whether A. donax rhizomes transported water between ramets. Hydrogen isotopic–enriched water was applied on three 1 m diameter areas, and rhizome and soil samples were collected beyond the watering zone after 5, 24 and 48 h of the last watering. Logistic modelling indicated that water was able to move laterally at least 3.5 m. The second objective was to determine whether clonal integration enhanced growth and survival of A. donax ramets. We compared growth‐related responses in paired 1 m2 plots with severed and intact rhizomes. In the first 19 days, rhizome severing nearly doubled ramet density, while by 77 days, the intact rhizomes produced 67% taller stems with 49% greater diameter and showed higher survival rate after flooding. This study provides initial evidence that physiological integration could be an important mechanism in A. donax, which can enhance its competitive abilities, accelerate rates of encroachment and strengthen its capability to recolonise disturbed areas. Our results highlight an important consideration of clonal invasive species in weed management.
Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation
Authors: Bowen T. Scott , Rossiter Harry B. , Benson Alan P. , Amano Tatsuro , Kondo Narihiko , Kowalchuk John M. , Koga Shunsaku
Published: July 2013

New findings

What is the central question of the study?

Does a transient overshoot in skeletal muscle deoxygenation (reflecting a kinetic mismatch of microvascular O2 delivery to consumption) and/or its spatial distribution slow the adjustment of oxidative energy provision at the onset of exercise?

What is the main finding and its importance?

Slowed oxidative energy provision at the onset of exercise was correlated with the transient skeletal muscle deoxygenation peak and the reduced spatial distribution, measured by quantitative near‐infrared spectroscopy. It was not correlated with a microvascular O2 delivery‐to‐consumption mismatch per se. This suggests that an absolute, rather than kinetic, mismatch of microvascular O2 delivery and consumption limits the kinetics of muscular oxidative energy provision, but only when muscle deoxygenation reaches some ‘critical’ level.

It remains unclear whether an overshoot in skeletal muscle deoxygenation (HHb; reflecting a microvascular kinetic mismatch of O2 delivery to consumption) contributes to the slowed adjustment of oxidative energy provision at the onset of exercise. We progressively reduced the fractional inspired O2 concentration () to investigate the relationship between slowed pulmonary O2 uptake () kinetics and the dynamics and spatial distribution of absolute [HHb]. Seven healthy men performed 8 min cycling transitions during normoxia (), moderate hypoxia () and severe hypoxia (). uptake was measured using a flowmeter and gas analyser system. Absolute [HHb] was quantified by multichannel, time‐resolved near‐infrared spectroscopy from the rectus femoris and vastus lateralis (proximal and distal regions), and corrected for adipose tissue thickness. The phase II time constant was slowed (P < 0.05) as decreased (normoxia, 17 ± 3 s; moderate hypoxia, 22 ± 4 s; and severe hypoxia, 29 ± 9 s). The [HHb] overshoot was unaffected by hypoxia, but the transient peak [HHb] increased with the reduction in (P < 0.05). Slowed kinetics in hypoxia were positively correlated with increased peak [HHb] in the transient (r2= 0.45; P < 0.05), but poorly related to the [HHb] overshoot. A reduction of spatial heterogeneity in peak [HHb] was inversely correlated with slowed kinetics (r2= 0.49; P < 0.05). These data suggest that aerobic energy provision at the onset of exercise may be limited by the following factors: (i) the absolute ratio (i.e. peak [HHb]) rather than the kinetic ratio (i.e. [HHb] overshoot) of microvascular O2 delivery to consumption; and (ii) a reduced spatial distribution in the ratio of microvascular O2 delivery to consumption across the muscle.
Comparison of Flow and Heat Transfer Distributions in a Can Combustor for Radial and Axial Swirlers Under Cold Flow Conditions
Authors: Carmack Andrew , Ekkad Srinath , Kim Yong , Moon Hee-Koo , Srinivasan Ram
Published: July 2013

A comparison study between axial and radial swirler performance in a gas turbine can combustor was conducted by investigating the correlation between combustor flow field geometry and convective heat transfer at cold flow conditions for Reynolds numbers of 50,000 and 80,000. Flow velocities were measured using particle image velocimetry (PIV) along the center axial plane and radial cross sections of the flow. It was observed that both swirlers produced a strong rotating flow with a reverse flow core. The axial swirler induced larger recirculation zones at both the backside wall and the central area as the flow exits the swirler, and created a much more uniform rotational velocity distribution. The radial swirler however, produced greater rotational velocity as well as a thicker and higher velocity reverse flow core. Wall heat transfer and temperature measurements were also taken. Peak heat transfer regions directly correspond to the location of the flow as it exits each swirler and impinges on the combustor liner wall.
A Family of Remote Center of Motion Mechanisms Based on Intersecting Motion Planes
Authors: Li Jianmin , Zhang Guokai , Müller Andreas , Wang Shuxin
Published: July 2013

If a part of a mechanism is restrained to rotate about a point not physically belonging to it, the mechanism is called a remote center-of-motion (RCM) mechanism. The RCM mechanisms are generally designed especially for robot-assisted minimally invasive surgery (MIS) systems, for which great progress has been made in recent years. An RCM mechanism type synthesis method is proposed in this paper by generalizing the intersection of motion planes. The existence of such motion planes is the fundamental feature of the classic Sarrus mechanism, for instance. The basic principle of the type synthesis method is to combine some typical planar mechanisms where their respective motion planes are free to tilt. Hence, the intersection line varies as the planes tilt. There is one invariant point on this intersection line, however, and this is the RCM point. The proposed method is used to design a class of spatial RCM mechanisms. And the kinematic characteristics of them are presented in this paper. In particular, several fully parallel two degree-of-freedom (DOF) RCM mechanisms and a 1-DOF RCM mechanism are considered in detail. Two spatial 3-DOF overconstrained RCM mechanisms are also obtained by the proposed method.
Measuring Failures and Correction Methods for Pneumatic Multi-Hole Probes
Authors: Hoenen Herwart T. , Kunte Robert , Waniczek Phillip , Jeschke Peter
Published: July 2013

Systematic measurements have been performed in a free stream in order to analyse the measuring behaviour of pneumatic multi-hole probes in the gradient field of a wake of an airfoil. The five-hole probe was traversed in different axial distances from the trailing edge and the results were compared to PIV and hot film probe measurements. The direct comparison of the three measurement techniques shows that too small axial distances between a five-hole probe and an airfoil trailing edge introduce significant measurement errors. Different effects were analysed in order to evaluate their influence on the measuring results and to estimate the deviation from the real flow properties. The limitations of probe measurements and the influences of the probe on the flow field are discussed. It is explained how pneumatic multi-hole probe measuring data can be corrected in order to improve the measuring results. In order to demonstrate the suitability of the correction method for turbo machinery application it is applied to measurement results of an axial compressor test rig.
Ejector Scavenging of Bearing Chambers: A Numerical and Experimental Investigation
Authors: Flouros Michael , Cottier Francois , Hirschmann Markus , Kutz Joachim , Jocher Agnes
Published: July 2013

Oil system architecture in aero engines has remained almost the same for the last 30 years. At least one oil feed pump is responsible for distributing pressurized oil into the bearing chambers and several scavenge pumps are responsible for evacuating the bearing chambers from the oil and the air mixture. Air is used as the sealing medium in bearing chambers and is the dominant medium in terms of volume occupation and expansion phenomena.

In order to simplify the oil system architecture and thus improve the system’s reliability with less mechanical parts and also decrease weight an ejector system has been designed for scavenging bearing chambers. The idea behind the ejector is to use high pressure oil from the feed pump and use it for feeding the ejector’s primary jet. Through the momentum transfer between the pressurized oil at the jet’s tip and the two phase mixture of air and oil from the bearing chamber the mixture will be discharged into the oil tank. In order to design the ejector for aero engine applications, engine relevant performance conditions had to be considered. The design was performed using a one dimensional analysis tool and then considerably refined by using the numerical tool ANSYS CFX. In a further step the ejector was manufactured out of pure quartz glass and was tested in a lube rig with a bearing chamber which has evolved from a real engine application. In the bearing chamber engine relevant performance conditions were simulated. Through the provided instrumentation for pressures, temperatures and air/oil flows the performance characteristics of the ejector were assessed and were compared to the analytic and numerical results. A high speed camera was used to record the two phase flow downstream of the bearing chamber in the scavenge pipe.

This work is part of the European Union funded research programme ELUBSYS (Engine LUBrication System TechnologieS) within the 7th EU Frame Programme for Aeronautics and Transport (AAT.2008.4.2.3).
Fuelling Micro Gas Turbines With Vegetable Oils: Part II — Experimental Analysis
Authors: Cavarzere A. , Morini M. , Pinelli M. , Spina P. R. , Vaccari A. , Venturini M.
Published: July 2013

The application of bio-fuels in automotive, power generation and heating applications is constantly increasing. However, the use of straight vegetable oil (pure or blended with diesel) to feed a gas turbine for electric power generation still requires experimental effort, due to the very high viscosity of straight vegetable oils.

In this paper, the behavior of a Solar T-62T-32 micro gas turbine fed by vegetable oils is investigated experimentally. The vegetable oils are supplied to the micro gas turbine as blends of diesel and straight vegetable oils in different concentrations, up to pure vegetable oil.

This paper describes the test rig used for the experimental activity and reports some experimental results, which highlight the effects of the different fuels on micro gas turbine performance and pollutant emissions. Moreover, an identification model is set up to predict the behavior of the considered gas turbine, when fuelled by vegetable oil, and the sensitivity of micro gas turbine thermodynamic measurements and emissions is quantitatively established.
An Improved Nickel Based MIMS Thermocouple for High Temperature Gas Turbine Applications
Authors: Scervini Michele , Rae Catherine
Published: July 2013

A new Nickel based thermocouple for high temperature applications in gas turbines has been devised at the Department of Material Science and Metallurgy of the University of Cambridge. This paper describes the new features of the thermocouple, the drift tests on the first prototype and compares the behaviour of the new sensor with conventional mineral insulated metal sheathed Type K thermocouples: the new thermocouple has a significant improvement in terms of drift and temperature capabilities. Metallurgical analysis has been undertaken on selected sections of the thermocouples exposed at high temperatures which rationalises the reduced drift of the new sensor. A second prototype will be tested in follow-on research, from which further improvements in drift and temperature capabilities are expected.
Study on the Flow Characteristics of High-Pressure and Dense-Phase Pneumatic Conveying of Different Pulverized Coal in IGCC Field
Authors: Lu Peng , Han Dong , Pu Wenhao , Yue Chen
Published: July 2013

Entrained flow coal gasification is the key technology in IGCC field for its cleanness and high-efficiency. High-pressure and dense-phase pneumatic conveying of pulverized coal is of great importance for the entrained flow pulverized coal gasification. There are great differences between dense-phase pneumatic conveying systems at high pressure and common pneumatic conveying systems because of its lower conveying speed, high solid concentration and complex flow patterns.

By changing conveying pressure, total differential pressure and fluidizing gas flow rate, experimental investigations were conducted on the conveying characteristics of pulverized coal with different coal category, different particle size, and different moisture content. The results showed that pneumatic conveying at high pressure is more propitious to obtain higher solid flux, higher solid-gas ratio and lower velocity transport. Solid flux increased with the total differential pressure but the trend was lowered at last due to the system limit. Solid-gas ratio increased at first and then decreased with the total differential pressure. Both solid flux and solid-gas ratio increased slightly with fluidizing gas flow rate at first and then decreased a little for the pulverized coal of two different particle sizes. Pulverized coal with the smaller particle size possessed better conveying ability and was easier to obtain higher solid-gas ratio. Solid flux of Inner Mongolia lignite decreased with the increasing moisture content in the pulverized coal. Conveying ability of Yanzhou bituminous coal was the best and Inner Mongolia bituminous coal was the worst among the three representative coal kinds in China tested. The characteristics of the pressure drops at different pipeline test sections were investigated considering the total differential pressure, solid-gas ratio, particle sizes and moisture content, respectively. Supplemental gas flow rate should be restricted to a range in order to transport successfully when conveying Inner Mongolia bituminous coal of 300μm. The work above will provide valuable experiences for future research on high-pressure and dense-phase pneumatic conveying of pulverized coal in IGCC field.
Influence of Coal Rank on the Process of Plasma Aided Gasification
Authors: Messerle V. E. , Ustimenko A. B. , Slavinskaya N. A. , Riedel U.
Published: July 2013

This paper describes numerical and experimental investigations of coal gasification in a combined arc-plasma entrained flow gasifier. The experimental installation is intended to operate in the electric power range of 30–100 kW, mass averaged temperature 1800–4000 K, coal dust consumption 3–10 kg·h−1 and gas-oxidant flow 0.5–15 kg·h−1.

The numerical experiments were conducted using the PLASMA-COAL computer code. It was designed for computation of the processes in plasma gasifiers. This code is based on a one-dimensional model, which describes the two-phase chemically reacting flow with an internal plasma source. The thermo-chemical conversion of the oxidizer-coal mixture is described through formation of primary volatile products, their conversion in the gas phase and the coke residue gasification reactions.

Kazakhstan Ekibastuz bituminous coal of 40% ash content, Germany Saarland bituminous coal of 10.5% ash content and 14% ash content bituminous coal from the Middleburg opencast mines, South Africa, were used for the investigation.

Performed investigations demonstrate that regardless of the coal quality the plasma assisted coal gasification allows obtaining a pure synthesis gas at a ratio of H2:CO≥1.
Tension–Compression Fatigue of a SiC/SiC Ceramic Matrix Composite at Elevated Temperature
Authors: Ruggles-Wrenn M. B. , Jones T. P.
Published: July 2013

Tension-compression fatigue behavior of a non-oxide ceramic composite with a multilayered matrix was investigated at 1200°C in laboratory air. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated Hi-Nicalon™ fibers woven in an eight-harness-satin weave (8HSW). Fiber preforms had pyrolytic carbon fiber coating with boron carbon overlay applied. Tension-compression fatigue behavior was studied for fatigue stresses ranging from 80 to 200 MPa at a frequency of 1.0 Hz. The R ratio (minimum stress to maximum stress) was −1.0. Fatigue run-out was defined as 2×105 cycles. Fatigue limit was 80 MPa. Specimens that achieved fatigue run-out were subjected to tensile tests to failure to characterize the retained tensile properties. The material retained 100% of its tensile strength. Reductions in tensile modulus and in compressive modulus were negligible. Composite microstructure, as well as damage and failure mechanisms were investigated.
Energy and Cost Analysis of Small Size CHP Coal Gasification Plants Integrated With Syngas Storage Systems
Authors: Cau Giorgio , Cocco Daniele , Serra Fabio
Published: July 2013

This study evaluates the load modulation capabilities of small and medium size CHP systems based on integrated coal gasification and syngas storage (ICGSS) power plants. ICGSS systems can perform a load-following service since a portion of the produced syngas is stored during periods of low energy demand and used to increase power output during periods of peaking demand. In particular, the main energy and economic performance of ICGSS power generation plants were evaluated with reference to three different prime movers (gas turbines, internal combustion engines and hybrid fuel cell systems) and as a function of the required electrical load curve. Moreover, a preliminary economic analysis was also carried out to evaluate the energy production cost in comparison with base-load energy production cost.

The results of the study show that ICGSS power plants offer considerable scope for enhancing operating flexibility and load modulation capabilities of CHP systems based on coal gasification. In comparison to coal gasification power plants designed to produce only base-load energy, ICGSS systems require a more powerful prime mover and a larger coal gasification section. In the field of duty-cycles of more likely interest, the coal gasification section needs to be enlarged by 5–50% and a fraction from 2% to 16% of the produced syngas needs to be stored. ICGSS plants based on hybrid fuel cells performed better in terms of electrical efficiency. Moreover, with respect to the corresponding base-load systems, electrical efficiency decreases by about 2–3 percentage points for ICGSS-GT and ICGSS-ICE, while it increases by about 1–2 percentage points for ICGSS-HFC. Finally, syngas storage can reduce energy costs in CHP systems, especially in the case high peaking electricity requirements, large useful heat productions and by using ICGSS based on ICE as prime movers.
Aeroacoustic Computations of Contra-Rotating Open Rotors Using the Nonlinear Harmonic Method and a Chorochronic Approach
Authors: Hoffer P.-A. , Deconinck T. , Hirsch Ch. , Ortun B. , Canard-Caruana S. , Rahier G. , Pascal S. , Caruelle B.
Published: July 2013

Due to their great potential for fuel saving, Contra-Rotating Open Rotors (CRORs) receive renewed interest by the airframers and the engine manufacturers. The inherent high efficiency of this propulsion system, however, is potentially offset by the level of noise emitted by the open blades. The acoustic impact on passengers and community may represent a major issue to their environmental acceptance. Fast and robust noise prediction tools are clearly required to support the development of quieter propellers and their integration in future civil aeronautical transport. The most common strategy for noise estimation consists in a two-step approach, based on the Lighthill analogy: unsteady near-field aerodynamic flow simulation to evaluate the noise sources, coupled to a far-field acoustic propagation code.

Focus is given here on two structured grid flow solvers employed to investigate a scale-model of a 12×10 pusher CROR. The unsteady aerodynamic three-dimensional flow is indeed computed for typical cruise conditions using both the nonlinear harmonic method (NLH) of FINE™/Turbo software and elsA’s chorochronic technique. The evaluation of the far-field noise based on the aerodynamic fields is then carried out with the KIM code, Onera’s acoustic propagation code based on the Ffowcs-Williams and Hawkings (FW-H) formulation.

The obtained results enable an analysis of the complex aerodynamic interactions between the two propellers that generate interaction tones in the acoustic signature of the propulsion system. A comparison in terms of numerical settings, computational costs and flow fields is performed between the two CFD methods, which show an excellent match of the predicted global performance of the propulsion system. Some differences in the predicted acoustic signatures are discussed in the paper.
Alternative Fuels Based on Biomass: An Investigation of Combustion Properties of Product Gases
Authors: Herzler Jürgen , Herbst Julia , Kick Thomas , Naumann Clemens , Braun-Unkhoff Marina , Riedel Uwe
Published: July 2013

Fuels from low quality feedstock such as biomass and biomass residues are currently discussed with respect to their potential to contribute to a more sustainable electrical power supply. In the present work, we report on the study of generic representative gas mixtures stemming from the gasification of different feedstock, from wood and algae. Two major combustion properties — burning velocities and ignition delay times — were measured for different parameters: (i) for two pressures −1 bar and 3 bar – at a constant preheat temperature T0 = 373 K, to determine burning velocities by applying the cone angle method; and (ii) for elevated pressures — up to 16 bar — in the temperature range between about 1000 and 2000 K, at fuel-equivalence ratios φ of 0.5 and 1.0, to obtain ignition delay times by applying the shock tube method. Additional studies performed in our group on gas mixtures of natural gas, methane, and hydrogen were also taken into account -as major components of biogenic gas mixtures. It was found that the reaction behavior of the wood gasification product (N2, CO, H2, CO2, CH4) is mainly determined by its H2 content, besides CH4; methane determines the kinetic behavior of the algae fermentation product (CH4, CO2, N2) due to its relatively high amount. Detailed chemical kinetic reaction models were used to predict the measured data. The trends and main features were captured by predictions applying different reaction models. The agreement of the experiments and the predictions is dependent on the pressure range.
Airframe Installation Effects on the Jet Exhausting a Coaxial Nozzle System of a Gas Turbine Engine
Authors: Mihaescu Mihai , Semlitsch Bernhard , Fuchs Laszlo , Gutmark Ephraim J.
Published: July 2013

Jet engine installation effects can significantly affect the behavior of the exhausting flow otherwise axisymmetric for an axial-symmetric nozzle configuration. Considering the problem associated solely with the turbulent jet (i.e. neglecting jet interaction with the airframe or the flight effects) has severe limitations on accurately predicting the real case scenario. It should also be emphasized that the major sources of noise for an aircraft are the high velocity, turbulent hot jets exhausting aircraft’s gas turbine engines. Therefore, the prediction of the compressible jet by including wing and pylon effects represents today a topic of high interest in aeroacoustics.

A numerical study is carried out for analyzing the flow associated with a separate flow nozzle system with and without installation effects. The Baseline case (without airframe installation) is compared with the case in which only the pylon is considered and with the case where the wing and the pylon are interfering with the jet engine. The simulations are performed with and without forward-flight effects. The tertiary flow increases the length of the potential core region while limiting the radial spread of the jet. The airframe installation effects increase the jet spreading underneath the pylon-nozzle-wing assembly while lowering the production of turbulence in that region. Particle Imaging Velocimetry experimental flow data are used to validate the computational results for the Baseline and the Pylon cases without the forward-flight effects.
Modeling of a Turbofan Engine Start Using a High Fidelity Aero-Thermodynamic Simulation
Authors: Fuksman Igor , Sirica Steven
Published: July 2013

Simulating the thermodynamics of a multi-spool turbofan engine during engine start can present challenges to the conventional high fidelity aero-thermodynamic simulation. The conventional high fidelity aero-thermodynamic simulation uses an iterative solver technique to preserve flow continuity and conservation of energy based on component maps and subsystem characteristics. Traditionally, operation of such simulations have been limited to regions from self-sustaining idle to maximum power, where component and subsystem representation has been well defined and engine operating pressures are sufficient to ensure one-directional flow. However, simulating transient operation which initiates from engine “off” condition followed by starter engagement and fuel introduction, presents a new set of challenges. These include the modeling of the engine “off” state itself, as well as two aspects of the starting process particular to a multi-spool turbofan: the modeling of the flow passing through the entire core stream even though only the high pressure shaft is rotating, and the modeling of the flow split into the bypass stream when the fan is not rotating. This paper discusses the modeling techniques that have been developed to overcome these challenges in order to ensure the smooth operation starting with engine off and continuing through the regions of starter engagement, fuel addition, and starter disengagement leading to normal engine operating regime.
Modeling of Structural Vibration for Motor Chamber Internal Flow Studies
Authors: Greatrix D. R. , Kudriavtsev V.
Published: July 2013

Axial, radial and tangential structural oscillation of various propulsion system motor chamber walls is demonstrated to be able to produce substantial pressure wave amplitudes within the internal flow. Predicted resonant driving frequencies for forced rigid vibration may vary somewhat from the ideal acoustic estimate, depending on the grid density employed in the given numerical model. Similarly, predicted limiting pressure wave amplitudes may tend to asymptote somewhat higher in the case of radial and tangential structural motion, as the grid density is increased (and the corresponding time step decreased) for the numerical solver. Free dynamic structural deformation (in addition to any net rigid-body motion that might be involved) is illustrated to also have an appreciable influence on internal gasdynamic wave behavior.
CFD Modeling of Steam Methane Reformer
Authors: Mehrotra Vibhor , Rosendall Brigette , Heath Alasdair , Berkoe Jonathan
Published: July 2013

This paper presents the use of advanced computer simulation (coupled Computational Fluid Dynamics and process modeling) to determine the effects of burner change out in a steam-methane reformer (SMR). SMR’s are used to generate hydrogen for oil refinery operation and synthesis gas for chemical plant production. A stream of natural gas and steam reacts inside a large number of catalyst-filled tubes housed inside the SMR furnace. Burner replacement in the furnace can result in reduced hydrogen production, decreased efficiency, and unstable operation. To help select a suitable replacement burner and optimize furnace performance CFD modeling was used to identify the impact of different burners on the following key SMR design parameters: • Local heat flux profiles on the reformer tubes; • Local peak and average reformer tube skin temperatures; • Heat Flux in the pre-heat tubes; • SMR Hydrogen production and process conditions. With a replacement burner selected, the ‘coupled’ CFD model was then used to predict the burner-firing pattern that maximizes hydrogen production within the SMR design constraints.
Numerical and Experimental Analysis of an Evaporation Cooler
Authors: Kickinger Robert , Wimmer Peter , Leibinger Helmut
Published: July 2013

Evaporation coolers are commonly used to cool hot off-gases by injecting water droplets, which vaporize and thus cool the off-gas so that it can be filtered in the next process step. In this paper the flow and heat and mass transfer in a full scale industrial evaporation cooler are predicted with CFD methods. Three different configurations are compared and evaluated with respect to the flow homogeneity at the spray nozzle plane. In addition, the cold air flow without droplet evaporation in a lab scale model is investigated with CFD as well as PIV (particle image velocimetry) measurements and comparisons are given. In the CFD simulation model all phases involved (off-gas, water droplets, water vapor and dust) are considered. Water droplets and the dust phase are modelled by an Euler/Lagrangian dispersed phase model which allows for a phase change from water droplets to vapor. The mass fraction of water vapor is computed by a diffusion/convection equation. The equations of the Eulerian and Lagrangian phases are fully coupled (the influence of the dispersed phases on the continuous phases and the phase change from water droplets to vapor is realized by appropriate source terms in the Eulerian phase equations). Turbulent particle dispersion is modelled by a stochastic tracking technique.
Reynolds Stress Turbulence Models for Prediction of Shear Stress Terms in Cross Flow Film Cooling — Numerical Simulation
Authors: Javadi Aliyar , Javadi Khodayar , Taeibi-Rahni Mohamad , Keimasi Mohammad Reza
Published: July 2013

Reynolds stress models are computationally more complex and time consuming but, have the potential of greater accuracy and wider applicability. Turbulent cross flows and film cooling have highly complex characteristics. In this work, we computationally simulated a three-dimensional, separated hole film cooling problem of flow over a flat plate, using Reynolds stress model (RSM) with wall function and zonal (κ-ε)/(κ-ω) turbulence model (shear stress transport model or SST). The Reynolds number of the jet was 4700. Our computational domain included the space above plate plus the film cooling jet channel. In our numerical simulation, the SIMPLE finite volume method with a non-uniform staggered grid was implemented. Our results were compared with Ajersch et al. experimental and numerical work’s (κ-ε turbulence model). Also, they were compared with Keimasi and Taeibi-Rahani’s numerical simulation work (SST turbulence model). Comparison between the measured and computed results show, that RSM/SST turbulence model in our work has better agreement with experimental data in most cases.