bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploration of Coriolis Force on the Linear Stability of Couple Stress Fluid Flow Induced by Double Diffusive Convection
Authors: Naveen Kumar S. B. , Shivakumara I. S. , Shankar B. M. 
Published: September 2019

Abstract
In this paper, the effect of Coriolis force is explored on convective instability of a doubly diffusive incompressible couple stress fluid layer with gravity acting downward. A linear stability analysis is used to obtain the conditions for the onset of stationary and oscillatory convection in the closed form. Being a multiparameter instability problem, results for some isolated cases have been presented to illustrate interesting corners of parameter space. It is found that the neutral curve for oscillatory onset forms a closed-loop which is separate from the neutral curve for stationary onset indicating the requirement of three critical thermal Rayleigh numbers to specify the linear instability criteria instead of the usual single value. Besides, the simultaneous presence of rotation and the addition of heavy solute to the bottom of the layer exhibit an intriguing possibility of destabilizing the system under certain conditions, in contrast to their stabilizing effect when they are present in isolation. The implication of couple stresses on each of the aforementioned anomalies is clearly brought out. The spatial wavelength of convective cells at the onset is also discussed.
A Novel Activated Carbon Enabled Steam Generation System Under Simulated Solar Light
Authors: Mishra Ashreet , Nnanna Agwu A. G. 
Published: September 2019

Abstract
Studies on carbon nanotubes (CNT), Au, and Ag solar enabled steam generation with potential application in water purification, distillation, and sterilization of medical equipment are ongoing. The key challenge with these nanoparticles is the cost of production hence limiting its full application for clean water production. This work for the first time reports on activated carbon enabled steam generation hence addressing the cost limitations of metallic nanoparticles. Activated carbon has high solar absorptivity at various wavelengths of visible light under low concentration. Experiments were carried out using activated carbon and CNT nanofluids and polyurethane (PU) membrane with immobilized activated carbon and CNT. A simulated solar light of 1 kW ∼1 sun was used. The rate of evaporation, temporal and spatial evolution of bulk temperature in the water were monitored automatically and recorded for further data reductions. Parametric studies of the effect of nanoparticle concentration, water quality, and salinity were performed. Experimental evidence showed that activated carbon has potential in water purification. We reported for the first time that optimal activated carbon concentration for maximum steam generation is 60 vol %. We also obtained a 160% increase in steam production rate at 60% concentration of activated carbon when compared with de-ionized water.
Numerical Investigation on the Effect of Tube Geometry and Feeder Height on the Heat Transfer Performance of Horizontal Tube Falling Film Evaporation
Authors: Balaji D. , Velraj R. , Ramana Murthy M. V. 
Published: September 2019

Abstract
This paper discusses about the effect of tube geometry and liquid feeder height on the heat transfer performance of falling film evaporation over the horizontal heated plain tubes. To investigate this, a two-dimensional computational fluid dynamics (CFD) model was developed, compared, and validated with published data available in the literature. A numerical simulation was carried out for varying liquid load, tube diameter, liquid feeder height, and corresponding changes in the heat transfer co-efficient (HTC), and mass transfer rate was recorded and analyzed. An attempt was also made to measure the thickness of the film around the tubes from the simulation model. Mechanisms that control the factors such as HTC, film thickness, and mass transfer were numerically investigated and discussed in this work. Numerical results indicated that low value of liquid film thickness appears approximately at the angular position of the range between 90 deg and 125 deg. Also the numerical investigation revealed that liquid film thickness decreases and HTC and mass transfer rate increases with the increase of feeder height. No remarkable change in film thickness was observed with increase in the tube diameter. This numerical study also proved that the prediction of thermally developed boundary region on the circumference of the tube could be possible in terms of mass transfer rate. It was also observed from the numerical study that the highest mass transfer rate takes place between the angle 135–165 deg near to the bottom of the tube.
On the Interaction of Swirling Flames in a Lean Premixed Combustor
Authors: Ramachandran Gopakumar , Dutta Ankit Kumar , Durairaj Harish , Chaudhuri Swetaprovo 
Published: September 2019

Abstract
Premixed or partially premixed swirling flames are widely used in gas turbine applications because of their compactness, high ignition efficiency, low NOx emissions and flame stability. A typical annular combustor consists of about twenty swirling flames, which interact (directly or indirectly) with their immediate neighbors even during stable operation. These interactions significantly alter the flow and flame topologies thereby bringing in some discrepancies between the single nozzle (SN) and multinozzle (MN), ignition, emission, pattern factor and flame transfer function (FTF) characteristics. For example, in MN configurations, application of a model based on SN FTF data could lead to erroneous conclusions. Due to the complexities involved in this problem in terms of size, thermal power, cost, optical accessibility etc., a limited amount of experimental studies has been reported, that too on scaled down models with reduced number of nozzles. Here, we present a detailed experimental study on the behavior of three interacting swirl premixed flames, arranged in-line in an optically accessible hollow cuboid test section, which closely resembles a three-cup sector of an annular gas turbine combustor with very large radius. Multiple configurations with various combinations of swirl levels between the adjacent nozzles and the associated flame and flow topologies have been studied. Spatio-temporal information of the heat release rate obtained from OH* chemiluminescence imaging is used along with the acoustic pressure signatures to compute the Rayleigh index (RI) so as to identify the regions within the flame that pumps energy into the self-excited thermoacoustic instability modes. It is found that the structure of the flame–flame interaction regions plays a dominant role in the resulting thermoacoustic instability. To resolve the flow and reactive species distributions in the interacting flames, two-dimensional (2D), three component stereoscopic particle image velocimetry (SPIV) and planar laser-induced fluorescence (PLIF) of hydroxyl radical is applied to all the test conditions. Significant differences in the flow structures among the different configurations were observed. Simultaneous OH-PLIF and SPIV techniques were also utilized to track the flame front, from which the curvature and stretch rates were computed. Flame surface density (FSD) which is defined as the mean surface area of the reaction zone per unit volume, is also computed for all the test cases. These measurements and analyses elucidate the structure of the interaction regions, their unique characteristics, and possible role in thermoacoustic instability.
Application of Stiffness Confinement Method in Transient Transport Calculation
Authors: Tang Chuntao 
Published: September 2019

Abstract
Stiffness confinement method (SCM) can effectively alleviate the stiffness in the neutron kinetics equation and can use larger time steps to obtain the same calculation accuracy and improve the computational efficiency. However, the existing SCM is mainly used to solve two group transient diffusion equations. In this paper, the SCM is employed to solve the multigroup transient transport calculation. On the basis of the original method of characteristics (MOC) code PEACH, the transient function is added, and the PEACH-K program is developed. Based on the numerical results of the latest published OECD/NEA C5G7-TD benchmark, it shows that the PEACH-K program developed in this paper has both high computing precision and good numerical stability.
A Study of the Reproducibility and Diversity of the Supply Chain in Manufacturing Hot Isostatically Pressed Type 316L Stainless Steel Components for the Civil Nuclear Sector
Authors: Kyffin William , Gandy David , Burdett Barry 
Published: September 2019

Abstract
Hot isostatic pressing (HIP) of type 316 L stainless steel powder has been an established manufacturing practice for more than 25 years in the oil and gas sector and more recently in the naval defense sector. To demonstrate the capability of the powder metallurgy HIP (PM/HIP) for nuclear power applications, a systematic study of 316 L commercial powder production, encapsulation/consolidation providers, and selected HIP parameters was undertaken by the Nuclear AMRC in collaboration with the Electric Power Research Institute (EPRI). In this study, the 316 L powder specification limited the oxygen content of the powder to under 130 parts per million (ppm), which reflects the improvements that commercial powder suppliers have been making over the past decade to ensure greater powder cleanliness. The test program assessed powder supply, HIP service provider, and HIP sustain time. Excellent test results were achieved across the full range of variables studied with all billets meeting the specification requirements of ASTM A988 and additional requirements imposed based on nuclear manufacturing standards. Significantly, the study demonstrated the robustness of the PM/HIP supply chain, as material produced via differing HIP service providers resulted in very consistent material properties across the destructive test program. Furthermore, no significant difference in material properties was noted for material HIP between 2 and 8 h hold time, suggesting that the HIP process window is large. Both these results are significant from an end-user standpoint as they highlight the uniformity of the process through the full manufacturing cycle from powder procurement to destructive testing. Despite all material passing specification requirements, some property variation was noted for differing powder suppliers. Considering the systematic approach, this was attributed to powder composition, with both low oxygen and high nitrogen contents contributing to improvements in Charpy impact strength and tensile strength, respectively.
Hydrodynamic Cause Analysis for Roof Damage on Water Storage Tank
Authors: Ryu Ki-Wahn 
Published: September 2019

Abstract
The causes of roof damage found on a large-scale water storage tank were investigated using hydrodynamic analysis. All operation and weather data, such as temperature inside and outside of the storage tank, atmospheric pressure, water level according to time, condensed water check inside pipelines, snowfall, and wind speed, were precisely reviewed. Four potential scenarios were postulated to estimate the vacuum pressure, presumed to be a direct cause of the roof damage to the storage tank. In the scenarios, an energy equation with a friction loss for pipelines and fittings was adopted to compute the pressure differences between the inlet and outlet of the ventilation and overflow pipes. A timewise pressure drop for the condition of fully clogged connected lines during a discharge operation was also carried out. A sequence solution for the unsteady Bernoulli equation to represent the dynamic motion of a water column inside a loop seal was successfully derived. This can predict the vacuum pressure limit inside the storage tank required to drain out the water from the loop seal. The predicted vacuum pressure was compared with the vacuum pressure required to cause the buckling phenomena at the roof support structures. In-depth analysis of each scenario showed that the roof damage of the storage tank developed when the vacuum pressure reached over the estimated vacuum pressure limit. To prevent further roof damage, including the storage tank of the same design at other plant, change of the layout of the air ventilation line was recommended.
Nonlinear Vibration Prediction of a Highly Flexible Rotor Supported by an Axial Groove Journal Bearing Considering Journal Angular Whirling Motion
Authors: Koondilogpiboon Nuntaphong , Inoue Tsuyoshi 
Published: September 2019

Abstract
The difference in dynamic behavior of the rotor-bearing system supported by the bearing model that considers both lateral and angular whirling motions of the journal (model A), and the model that considers only lateral whirling motion (model B) is investigated. The rotor model consists of a slender shaft, a large disk, and two small disks supported by a self-aligning rolling element bearing (REB) and an axial groove journal bearing (JB) of length-to-diameter ratio (L/D) = 0.6. Three positions of the large disk: 410, 560, and 650 mm measured from the REB, are investigated. Numerical integration of the rotor-bearing system which is modally reduced to the first forward (FWD) mode is performed at above the onset speed of instability until either a steady-state journal orbit or contact between the journal and the bearing occurs to identify the bifurcation type. Numerical results using model A indicate subcritical bifurcation with the contact between the journal and the inboard (IB) side of the bearing in all three large disk positions, whereas those of model B indicate subcritical bifurcation when the large disk position is at 410 mm, and supercritical bifurcation is observed in the other two cases. Finally, the experiments at the same three large disk positions are performed. Subcritical bifurcation with the contact between the journal and the IB side of the bearing is observed in all large disk positions, which conforms with the calculation result of model A. Hence, model A is essential in nonlinear vibration analysis of a highly flexible rotor system.
Using Machine Learning to Predict Core Sizes of High-Efficiency Turbofan Engines
Authors: Tong Michael T. 
Published: September 2019

Abstract
With the rise in big data and analytics, machine learning is transforming many industries. It is being increasingly employed to solve a wide range of complex problems, producing autonomous systems that support human decision-making. For the aircraft engine industry, machine learning of historical and existing engine data could provide insights that help drive for better engine design. This work explored the application of machine learning to engine preliminary design. Engine core-size prediction was chosen for the first study because of its relative simplicity in terms of number of input variables required (only three). Specifically, machine-learning predictive tools were developed for turbofan engine core-size prediction, using publicly available data of two hundred manufactured engines and engines that were studied previously in NASA aeronautics projects. The prediction results of these models show that, by bringing together big data, robust machine-learning algorithms and data science, a machine learning-based predictive model can be an effective tool for turbofan engine core-size prediction. The promising results of this first study paves the way for further exploration of the use of machine learning for aircraft engine preliminary design.
Validation of a Turbine Blade Component Test With Frictional Contacts by Phase-Locked-Loop and Force-Controlled Measurements
Authors: Schwarz Stefan , Kohlmann Lukas , Hartung Andreas , Gross Johann , Scheel Maren , Krack Malte 
Published: September 2019

Abstract
In this paper, a validation approach for a turbine blade component test with frictional contacts is presented. The investigated system is derived from a high cycle fatigue test setup, where a turbine blade is base-excited in the clamped blade foot. The setup has been extended by laser scanning vibrometry, a force measurement platform, and feedback-controllers for both force level and phase. At first, a conventional validation of a linearized model of the system is performed at low amplitudes to ensure the correct modal basis for model reduction. After that, the nonlinear behavior around the fundamental mode is analyzed in detail. Frequency responses for different excitation levels and backbone curves are measured and assessed regarding repeatability and robustness of the measurement chain. Among other effects, overhanging branches of the frequency response were encountered. Nonlinear, amplitude-dependent modal frequencies and damping ratios are identified from the backbone curves. These data form the validation basis for a reduced-order model of the system considering nonlinear friction in the blade foot. The correlation of measurement and simulation is investigated and advantages and shortcomings of the different validation metrics are discussed.
Machining of Microholes in Thin Wires
Authors: Serizawa Masaki , Matsumura Takashi 
Published: September 2019

Abstract
Machining of microholes in thin wires is presented to manufacture the microdevices. A machine tool was developed to machine 0.1–0.15 mm diameter holes in 0.3 mm diameter titanium alloy wires with drills or end mills. In order to realize high stiffness and damping of the workpiece holding, the workpiece inserted into a polyurethane tube was clamped on a groove of a machine table. Blind and through holes were machined with controlling the position, the orientation, and the inclination of the holes. The cutting forces were measured in drillings of 0.1 mm diameter through holes and in milling of the inclined holes with a piezoelectric dynamometer. The damping effect of the polyurethane tube support appears in the dynamic components in the cutting force. The cutting forces were also simulated to discuss the effect of the tool positioning error with respect to the workpiece axis on the cutting force in an analytical force model. The X and Y components at engagement and exit of the tool increase with the positioning error. The positioning error should be reduced to improve the machining accuracy without the tool breakage in this operation.
Computational Fluid Dynamics-Based Throughflow Analysis of Transonic Flows in Steam Turbines
Authors: Ricci Martina , Pacciani Roberto , Marconcini Michele , Macelloni Paolo , Cecchi Stefano , Bettini Claudio 
Published: September 2019

Abstract
A computational fluid dynamics (CFD)-based throughflow solver is applied to the meridional analysis of low-pressure steam turbine modules. The throughflow code inherits its numerical scheme from a state-of-the-art CFD solver (TRAF code) and incorporates real gas capabilities, three-dimensional flow features, and spanwise mixing models. Secondary flow effects are introduced via a concentrated vortex model. Tip gap and shroud leakage effects are modeled in terms of source vectors in the system of governing equations. The impact of part-span shrouds and snubbers are accounted for, on a local basis, through suitable body force fields. The advection upstream splitting method (AUSM+-up) upwind strategy has been adopted as a basis to construct a numerical flux scheme explicitly suited for throughflow applications. The original formulation has been adapted to handle real gas flows and to embed the treatment of body force fields in a fully consistent framework. The capability of the procedure is assessed by analyzing the low-pressure modules of two large steam turbines designed and manufactured by Ansaldo Energia. These modules include rotor tip shrouds and part-span snubbers and feature supersonic flow and large blade twist. Throughflow predictions in terms of main performance figures and radial distributions of flow quantities are compared with experimental data and 3D steady viscous analyses. It will be shown how the proposed CFD-based throughflow model can be fruitfully used in the early stages of the design as it delivers predictions of comparable accuracy with 3D CFD analyses at a fraction of the computational time.
<p class="Body"><strong>Two new species of Cryptognathidae (Acari: Prostigmata) from north-western Iran</strong></p>
Authors: Mohammad Doustaresharaf Mojtaba , Bagheri Mohammad , Saber Moosa 
Published: September 2019

Herein, two new species of the family Cryptognathidae: Cryptognathus khaustovi sp. nov., collected from soil in Urmia and Favognathus kazemii sp. nov., collected from soil and litter in Mahabad, are described from north-western Iran. Also, Cryptognathus ayyldizi Akyol & Koç, 2010 is reported for the first time from Iran.
Barriers and facilitators for implementation of electronic consultations (eConsult) to enhance access to specialist care: a scoping review
Authors: Osman Mohamed A , Schick-Makaroff Kara , Thompson Stephanie , Bialy Liza , Featherstone Robin , Kurzawa Julia , Zaidi Deenaz , Okpechi Ikechi , Habib Syed , Shojai Soroush , Jindal Kailash , Braam Branko , Keely Erin , Liddy Clare , Manns Braden , Tonelli Marcello , Hemmelgarn Brenda , Klarenbach Scott , Bello Aminu K 
Published: September 2019

IntroductionElectronic consultation (eConsult)—provider-to-provider electronic asynchronous exchanges of patient health information at a distance—is emerging as a potential tool to improve the interface between primary care providers and specialists. Despite growing evidence that eConsult has clinical benefits, it is not widely adopted. We investigated factors influencing the adoption and implementation of eConsult services.MethodsWe applied established methods to guide the review, and the recently published Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews to report our findings. We searched five electronic databases and the grey literature for relevant studies. Two reviewers independently screened titles and full texts to identify studies that reported barriers to and/or facilitators of eConsult (asynchronous (store-and-forward) use of telemedicine to exchange patient health information between two providers (primary and secondary) at a distance using secure infrastructure). We extracted data on study characteristics and key barriers and facilitators were analysed thematically and classified using the Quadruple Aim framework taxonomy. No date or language restrictions were applied.ResultsAmong the 2579 publications retrieved, 130 studies met eligibility for the review. We identified and summarised key barriers to and facilitators of eConsult adoption and implementation across four domains: provider, patient, healthcare system and cost. Key barriers were increased workload for providers, privacy concerns and insufficient reimbursement for providers. Main facilitators were remote residence location, timely responses from specialists, utilisation of referral coordinators, addressing medicolegal concerns and incentives for providers to use eConsult.ConclusionThere are multiple barriers to and facilitators of eConsult adoption across the domains of Quadruple Aim framework. Our findings will inform the development of practice tools to support the wider adoption and scalability of eConsult implementation.