bluuebunny/crossref_metadata_2025_split huggingface dataset:
Severe asthma: Current management, targeted therapies and future directions—A roundtable report
Authors: McDonald Vanessa M. , Maltby Steven , Reddel Helen K. , King Gregory G. , Wark Peter A.B. , Smith Lorraine , Upham John W. , James Alan L. , Marks Guy B. , Gibson Peter G. 
Published: December 2016

ABSTRACT
Asthma is a chronic respiratory disease characterized by respiratory symptoms, airway inflammation, airway obstruction and airway hyper‐responsiveness. Asthma is common and directly affects 10% of Australians, 1–5% of adults in Asia and 300 million people worldwide. It is a heterogeneous disorder with many clinical, molecular, biological and pathophysiological phenotypes. Current management strategies successfully treat the majority of patients with asthma who have access to them. However, there is a subset of an estimated 5–10% of patients with asthma who have severe disease and are disproportionately impacted by symptoms, exacerbations and overall illness burden. The care required for this relatively small proportion of patients is also significant and has a major impact on the healthcare system. A number of new therapies that hold promise for severe asthma are currently in clinical trials or are entering the Australian and international market. However, recognition of severe asthma in clinical practice is variable, and there is little consensus on the best models of care or how to integrate emerging and often costly therapies into current practice. In this article, we report on roundtable discussions held with severe asthma experts from around Australia, and make recommendations about approaches for better patient diagnosis and assessment. We assess current models of care for patient management and discuss how approaches may be optimized to improve patient outcomes. Finally, we propose mechanisms to assess new therapies and how to best integrate these approaches into future treatment.
The Impact of Low Octane Primary Reference Fuel on HCCI Combustion Burn Rates: The Role of Thermal Stratification
Authors: Hagen Luke , Lavoie George , Wooldridge Margaret , Assanis Dennis 
Published: December 2016

A new experimental method was developed which isolated charge composition effects for wide levels of internal EGR (iEGR) at constant total EGR (tEGR) for negative valve overlap (NVO) homogeneous charge compression ignition (HCCI) combustion. Using this method, the effect of changing iEGR was examined for both research grade gasoline (RON = 90.5) and PRF40 across multiple engine speeds and at constant charge composition. For this study, the charge composition was defined as the total mass of fresh air, fuel and tEGR. Comparison also was made between the two fuels at a fixed iEGR level to isolate, independent of compositional effects, the effect of a low octane fuel on HCCI burn rates.
From the experimental results, for all engine speeds, for a given iEGR level, PRF40 was found to have a reduced burn duration and higher maximum heat release rate (HRR) compared with gasoline. PRF40 was found to have a nearly constant burn duration and HRR for a given load and CA50, largely independent of engine speed and iEGR level. Gasoline, for equivalent conditions, showed an increased burn duration at higher iEGR levels.
When comparing PRF40 to gasoline at fixed speed, combustion phasing and iEGR level, the increase in HRR was found to coincide with reduced intake valve closing (IVC) temperatures necessary to maintain constant combustion phasing for the PRF40. The reduced IVC temperature for PRF40 reduced the thermal stratification in-cylinder compared with gasoline and may have been the cause of this change. To examine the impact of thermal gradients relative to fuel chemistry, a multi-zone “balloon model” was used to evaluate experimental conditions. The model used a reduced chemical kinetic mechanism for PRFs with PRF87 representing gasoline. The results of the model demonstrated that when the in-cylinder temperature profiles between PRF40 and PRF87 were matched by adjusting wall temperature, the heat release rates were nearly identical. This result suggested the observed differences in burn rates between gasoline and PRF40 were influenced to a large degree by differences in thermal stratification, and to a lesser extent by differences in fuel chemistry.
Inverse Analysis of In-Cylinder Gas-Wall Boundary Conditions: Investigation of a Yittria Stabilized Zirconia Thermal Barrier Coating for Homogeneous Charge Compression Ignition
Authors: O’Donnell Ryan , Powell Tommy , Hoffman Mark , Filipi Zoran 
Published: December 2016

Thermal Barrier Coatings (TBC) applied to in-cylinder surfaces of a Low Temperature Combustion (LTC) engine provide opportunities for enhanced cycle efficiency via two mechanisms: (i) positive impact on thermodynamic cycle efficiency due to combustion/expansion heat loss reduction, and (ii) enhanced combustion efficiency. Heat released during combustion elevates TBC surface temperatures, directly impacting gas-wall heat transfer. Determining the magnitude and phasing of the associated TBC surface temperature swing is critical for correlating coating properties with the measured impact on combustion and efficiency. Although fast-response thermocouples provide a direct measurement of combustion chamber surface temperature in a metal engine, the temperature and heat flux profiles at the TBC-treated gas-wall boundary are difficult to measure directly. Thus, a technique is needed to process the signal measured at the sub-TBC sensor location and infer the corresponding TBC surface temperature profile. This task can be described as an Inverse Heat Conduction Problem (IHCP), and it cannot be solved using the conventional analytic/numeric techniques developed for ‘direct’ heat flux measurements.
This paper proposes using an Inverse Heat Conduction solver based on the Sequential Function Specification Method (SFSM) to estimate heat flux and temperature profiles at the wall-gas boundary from measured sub-TBC temperature. The inverse solver is validated ex situ under HCCI like thermal conditions in a custom fabricated radiation chamber where fast-response thermocouples are exposed to a known heat pulse in a controlled environment. The analysis is extended in situ, to evaluate surface conditions in a single-cylinder, gasoline-fueled, HCCI engine. The resulting SFSM-based inverse analysis provides crank angle resolved TBC surface temperature profiles over a host of operational conditions.
Such metrics may be correlated with TBC thermophysical properties to determine the impact(s) of material selection on engine performance, emissions, heat transfer, and efficiencies. These efforts will also guide next-generation TBC design.
Simulation of Combustion Recession After End-of-Injection at Diesel Engine Conditions
Authors: Jarrahbashi Dorrin , Kim Sayop , Genzale Caroline L. 
Published: December 2016

Recent experimental observations show that lifted diesel flames tend to propagate back towards the injector after the end of injection under conventional high-temperature combustion conditions. Earlier studies have referred to this phenomenon as “flashback,” but more recently the term “combustion recession” has been adopted to reflect findings that the process appears dominated by “auto-ignition” reactions upstream of the lifted flame after the end of injection. Since this process is only initiated after the end of injection, it is also closely linked to the end-of-injection entrainment wave and its impact on the transient mixture-chemistry evolution upstream of the lift-off length. A few recent studies have explored the physics of combustion recession with experimental and simplified modeling approaches, but the details of the chemical kinetics and convective-diffusive transport of reactive scalars in this phenomenon are still largely unexplored. There are also uncertainties in the capability of engine computational fluid dynamics (CFD) simulations to accurately capture entrainment wave and combustion recession phenomena.
In this study, highly-resolved numerical simulations have been employed to explore the mixing and combustion of a diesel spray after the end of injection and the influence of modeling choices on the prediction of these phenomena. The simulations are centered on a temperature sweep around the Engine Combustion Network (ECN) Spray-A conditions, from 800–1000 K, where different combustion recession behaviors are observed experimentally. Reacting spray simulations are performed in the open-source CFD software OpenFOAM, using a Reynolds-Averaged Navier-Stokes (RANS) approach with a traditional Lagrangian-Eulerian coupled formulation for two-phase mixture transport. Two reduced chemical kinetics models for n-dodecane by Yao et al. and Cai et al. are used to evaluate the impact of low-temperature chemistry and mechanism formulation on predictions of combustion recession behavior. Observations from the numerical simulations are consistent with recent findings that a two-stage auto-ignition sequence drives the combustion recession process; self-sustained reacting mixtures arise in distinct regions that are spatially separated from the lifted flame. Simulations with two different chemical mechanisms indicate that low-temperature chemistry reactions drive the likelihood for second-stage ignition and combustion recession that in turn strongly influence local entrainment in these mixtures and likelihood of combustion recession.
Numerical Study on Spray and Flame Lift-Off Length of Acetone-Butanol-Ethanol and Diesel Blends in a Constant Volume Chamber
Authors: Zhang Saifei , Xu Zhengxin , Wu Wei , Lee Chia-Fon F. 
Published: December 2016

Acetone-butanol-ethanol mixture (ABE) is being studied as an alternative fuel because it not only preserves the advantages of oxygenated fuels, but also lowers the cost of fuel recovery for butanol during fermentation. The previous experimental study on spray and flame lift-off length for diesel with 20% addition of ABE mixture, shows a shorter and narrower spray and a much longer flame lift-off length compared to those of neat diesel, which leads to considerably less soot emission level of ABE20.
In this study, a detailed mechanism capable of predicting the ignition delay for ABE as well as ABE-diesel blends is implemented to the KIVA-3V program to simulate the spray dynamics and lift-off length inside the constant volume chamber. The presented model is able to capture the trends with regard to ignition delay, combustion duration and peak pressure. The overall predictivity for ABE20 is better than that of D100. Spray penetration and the lift-off length for both fuels are simulated and the numerical definition for lift-off length is discussed. It is found that the threshold temperature to define lift-off length can be uniform under different ambient temperatures, but varies with respect to oxygen concentration. The simulations also agree with the measurements in predicting the lift-off length decreases as temperature and oxygen concentration increases. Finally, the simulation sooting tendency is presented to show that, due to the improved spray and combustion process of ABE-diesel blend, the soot emission level is much less than conventional diesel fuel.
Rapidly Pulsed Reductants for Diesel NOx Reduction With Lean NOx Traps: Comparison of Alkanes and Alkenes as the Reducing Agent
Authors: Reihani Amin , Patterson Brent , Hoard John , Fisher Galen B. , Theis Joseph R. , Lambert Christine K. , Smirnov Evgeny , Roemer Dirk 
Published: December 2016

Lean NOx Traps (LNTs) are often used to reduce NOx on smaller diesel passenger cars where urea-based Selective Catalytic Reduction (SCR) systems may be difficult to package. However, the performance of LNTs at temperatures above 400°C needs to be improved. The use of Rapidly Pulsed Reductants (RPR) is a process in which hydrocarbons are injected in rapid pulses ahead of the LNT in order to improve its performance at higher temperatures and space velocities. This approach was developed by Toyota and was originally called Di-Air (Diesel NOx aftertreatment by Adsorbed Intermediate Reductants) [1].
There is a vast parameter space that needs to be explored in order to maximize the NOx conversion at high temperatures and flow rates while minimizing the fuel penalty associated with the hydrocarbon injections. Four parameters were identified as important for RPR operation: (1) the flow field and reductant mixing uniformity; (2) the pulsing parameters including the pulse frequency, duty cycle, and rich magnitude; (3) the reductant type; and (4) the catalyst composition, including the type and loading of precious metal, the type and loading of NOx storage material, and the amount of oxygen storage capacity (OSC). In this study, RPR performance was assessed between 150°C and 650°C with several reductants including dodecane, propane, ethylene, propylene, H2, and CO. A novel injection and mixer system was designed that allowed for the investigation of previously unexplored areas of high frequency injections up to f = 100Hz.
Under RPR conditions, H2, CO, dodecane, and C2H4 provided approximately 80% NOx conversion at 500°C, but at 600°C the conversions were significantly lower, ranging from 40 to 55%. The NOx conversion with C3H8 was low across the entire temperature range, with a maximum conversion of 25% near 300°C and essentially no conversion at 600°C. In contrast, C3H6 provided greater than 90% NOx conversion over a broad range of temperature between 280°C and 630°C. Among the hydrocarbons, this suggested that the high temperature NOx conversion with RPR improves as the reactivity of the hydrocarbon increases.
Considerations in the Capacity Uprating of an EOR HRSG
Authors: Aumuller John J. , Lange Carlos F. , Humphries Michael J. 
Published: December 2016

In enhanced oil recovery operations, the steaming capacity of a heat recovery steam generating unit is limited by the available energy provided from the gas turbine generator, however, there are a number of other component parameters that limit the thermal and mechanical performance of any specific heat recovery steam generator. These additional parameters reside on both the flue gas side and water / steam side of the heat recovery steam generator.
Repetitive failures of steam generator components are evidence of damage mechanisms that are active during operation. Some of these damage mechanisms are explored to determine the immediate impact in up-rating the steam generators to higher capacity throughput and also, on longer term reliability. A resulting finding of this study examines the efficacy of using P22 low alloy piping in lieu of carbon steel piping to address flow accelerated corrosion.
Validation of a CFD Analysis Model for the Thermal-Hydraulic Response of PWR Steam Generator to a Steam Line Break
Authors: Jo Jong Chull , Min Bok Ki , Jeong Jae Jun 
Published: December 2016

This paper presents a validation of a computational fluid dynamics (CFD) analysis method for a numerical simulation of the transient thermal-hydraulic responses of steam generator (SG) secondary side to blowdown following a main steam line break (MSLB) at a pressurized water reactor (PWR).
To do this, the CFD analysis method was applied to simulate the same blowdown situation as in an experimental work which was conducted for a simplified SG blowdown model, and the CFD calculation results were compared with the experimental results.
As the result, both are in reasonably good agreement with each other. Consequently, the present CFD analysis model has been validated to be applicable for numerical simulations of the transient phase change heat transfer and flow situations in PWR SGs during blowdown.
Influence of Lode Angle on the ASME Local Strain Failure Criterion
Authors: Karpanan Kumarswamy , Thomas William 
Published: December 2016

Failure strain at any point on a structure is not a constant but is a function of several factors, such as stress state, strain rate, and temperature. Failure strain predicted from the uniaxial tensile testing cannot be applied to the bi-axial or tri-axial stress state. ASME Sec VIII-Div-2, and −3 codes give methods to predict the failure strain for multi-axial stress state by considering the triaxiality factor, which is defined as the ratio of mean stress to the equivalent stress. Failure strain predicted by the ASME method (based on the Rice-Tracey ductile failure model) is an exponential curve that relates the failure strain to the triaxiality factor. The ASME VIII-3 method also gives procedures to calculate failure strain for various material types: ferritic, stainless steel, nickel alloy, aluminum, etc.
Experimental results of failure strain at various stress states show that the failure strain is not only a function of the triaxiality factor, but also a function of the Lode angle. The Lode angle takes on the value of 1, 0, and −1 for tension, pure shear, and compression stress state, respectively. Experimental data shows that the failure strain is a 3D surface which has an exponential relation with triaxiality and a parabolic relation with the Lode angle. To validate the ASME failure strain prediction, this paper compares experimental failure strain test data from literature with the ASME predictions. The ASME predictions are non-conservative especially for moderately ductile materials such as aluminum and high strength carbon steel. A reduction factor on failure strain for low ductile material is presented using the relation between the R (yield/ultimate) and the stress ratio (shear/tensile stress).
The ASME method does not account for the environmental effects while calculating the failure strain. High pressure, high temperature (HPHT) subsea components designed using ASME VIII-3 code are subjected to various environments in subsea, such as seawater, seawater with cathodic protection (CP) and production fluid (crude oil). Experimental data shows that the Elongation (EL) and/or Reduction in Area (RA) from tensile testing decrease in these environments. Therefore, to account for any environment effect on the failure strain, reduced EL and RA can be used to predict the failure strain.
Investigation of Preparation Processes and Corrosion Resistance of NiCrBSi Coatings Fabricated by Laser-High Frequency Induction Hybrid Cladding
Authors: Lu Shuhua , Ling Xiang , Zhang Jinchun 
Published: December 2016

The surface of many key components used in petrochemical industry may be damaged by corrosion, wear and overheat during service. This damage can make a significant impact on the safe and reliable operation process of the device. Low alloy steel is widely used to manufacture pressure vessels and pipes because of the higher strength and good processing properties, but has poor corrosion resistance and wear resistance. Laser cladding is an advanced and effective surface modification technology. It can improve the surface properties of the matrix material at lower cost. But these claddings crack easily due to the high temperature gradient in the laser molten pool and physical properties differences between the cladding material and matrix. This problem has affected the development of laser cladding. Laser-high frequency induction hybrid cladding is a novel technology which combines laser beam heat source and induction power. It can decrease the cracks in the claddings effectively and has been received significant attentions in recent years.
Nickel base alloy powders have good corrosion resistance, wettability and high temperature lubricity. In this research, NiCrBSi composite claddings were fabricated on the surface of low alloy steel by the way of laser-high frequency induction hybrid cladding and coaxial powder feeding. The optimum cladding technology parameters to obtain the cladding layers that with good metallurgical combination, reasonable dilution rate and without cracks and defects were developed by optimizing the processing parameters such as laser power, powder feeding rate, laser scanning speed and induction heating temperature. The hardness distribution, microstructure, element distribution and phase of the cladding layers fabricated by the optimum parameters were systematically investigated by means of micro-hardness tester, optical microscopy (OM). Compared with the untreated material, experiment results show that the micro-hardness from substrate to NiCrBSi cladding layer exhibits step distribution, and the hardness of the NiCrBSi cladding layer is higher than that of the base metal. The microstructure showed good metallurgical bonding between NiCrBSi cladding and substrate had been achieved. In addition, directionally solidified microstructures were deposited. From the top to bottom of the cladding layer, the microstructures are, in order, equiaxed crystal, dendrite crystal, cellular crystal, columnar crystal and plane crystals. The corrosion resistance of the base metal and specimens manufactured by laser-high frequency induction hybrid cladding were evaluated in 3.5% NaCl solution by electrochemical testing. The experimental results demonstrate that the corrosion resistance of the NiCrBSi cladding layer fabricated by laser-high frequency induction hybrid cladding technology is better than the base metal.
Fatigue Performance of Stainless Steels (304L, 347) in Experiments Simulating NPP Operation With Hold Times
Authors: Karabaki Ertugrul , Twite Marius , Solin Jussi , Herbst Matthias , Mann Jonathan , Burke M. Grace 
Published: December 2016

Advanced Fatigue Methodologies (AdFaM), a joint project of European research laboratories, vendors and plant operators, was launched in 2014 to build on the results from recent laboratory studies of fatigue behavior of austenitic stainless steels under NPP-relevant conditions that showed improved lifetimes compared to the best fit to test data presented in NUREG/CR-6909, and to further investigate transferability between specimen test results and the fatigue behavior of NPP components during plant operation.
In particular, AdFaM has focused on an empirical and mechanistic investigation of the effects of hold times on fatigue life. A small number of previous test results suggest an increase in fatigue life for stabilized grades of austenitic stainless steel when hold times (ranging from several hours to days) are introduced into a test between periods of strain-controlled cyclic loading. Tests incorporating hold times may be more representative of material behavior in NPPs, where temperature transients due to start-ups, shutdowns and major power changes may be separated by long periods of steady state operation.
Under AdFaM, fatigue endurance tests incorporating hold times have been completed on stabilized and non-stabilized stainless steel grades (Types 304L and 347) and the mechanisms responsible for the observed variations in fatigue life have been investigated using a range of microscopy techniques.
Results confirm a significant extension of fatigue life due to hold times in both stabilized and non-stabilized grades. Life extension appears to be linked to hold hardening observed in cyclic behavior, and this link has been investigated through microstructural characterization of fatigue specimens examined before and after holding at elevated temperature.
This project helps to improve the understanding of transferability of results from small specimen tests (without hold times) to analysis of NPP components and provides insights that will contribute towards continuing development of fatigue design curves and analysis methods in Design Codes such as ASME Code Section III and KTA 3201/3211.
The AdFaM project is now complete. The valuable results and insights gained from this work demonstrate the significant benefits of collaborative research between various industrial and academic partners in the area of fatigue of NPP materials.