bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inferior parietal lobule is sensitive to different semantic similarity relations for concrete and abstract words
Authors: Montefinese Maria , Pinti Paola , Ambrosini Ettore , Tachtsidis Ilias , Vinson David 
Published: December 2020

AbstractSimilarity measures, the extent to which two concepts have similar meanings, are the key to understand how concepts are represented, with different theoretical perspectives relying on very different sources of data from which similarity can be calculated. While there is some commonality in similarity measures, the extent of their correlation is limited. Previous studies also suggested that the relative performance of different similarity measures may also vary depending on concept concreteness and that the inferior parietal lobule (IPL) may be involved in the integration of conceptual features in a multimodal system for the semantic categorization. Here, we tested for the first time whether theory‐based similarity measures predict the pattern of brain activity in the IPL differently for abstract and concrete concepts. English speakers performed a semantic decision task, while we recorded their brain activity in IPL through fNIRS. Using representational similarity analysis, results indicated that the neural representational similarity in IPL conformed to the lexical co‐occurrence among concrete concepts (regardless of the hemisphere) and to the affective similarity among abstract concepts in the left hemisphere only, implying that semantic representations of abstract and concrete concepts are characterized along different organizational principles in the IPL. We observed null results for the decoding accuracy. Our study suggests that the use of the representational similarity analysis as a complementary analysis to the decoding accuracy is a promising tool to reveal similarity patterns between theoretical models and brain activity recorded through fNIRS.
Both contextual regularity and selective attention affect the reduction of precision‐weighted prediction errors but in distinct manners
Authors: Hsu Yi‐Fang , Hämäläinen Jarmo A. 
Published: December 2020

AbstractPredictive coding model of perception postulates that the primary objective of the brain is to infer the causes of sensory inputs by reducing prediction errors (i.e., the discrepancy between expected and actual information). Moreover, prediction errors are weighted by their precision (i.e., inverse variance), which quantifies the degree of certainty about the variables. There is accumulating evidence that the reduction of precision‐weighted prediction errors can be affected by contextual regularity (as an external factor) and selective attention (as an internal factor). However, it is unclear whether the two factors function together or separately. Here we used electroencephalography (EEG) to examine the putative interaction of contextual regularity and selective attention on this reduction process. Participants were presented with pairs of regular and irregular quartets in attended and unattended conditions. We found that contextual regularity and selective attention independently modulated the N1/MMN where the repetition effect was absent. On the P2, the two factors respectively interacted with the repetition effect without interacting with each other. The results showed that contextual regularity and selective attention likely affect the reduction of precision‐weighted prediction errors in distinct manners. While contextual regularity finetunes our efficiency at reducing precision‐weighted prediction errors, selective attention seems to modulate the reduction process following the Matthew effect of accumulated advantage.
A Unified Probabilistic Framework for Cancer Risk Management
Authors: Rheinberger Christoph M. 
Published: December 2020

AbstractCancer risk assessments in the regulatory realm are often deterministic. Probabilistic approaches that allow characterizing and propagating uncertainty and variability are better suited to predict the socioeconomic impacts of regulating carcinogens. In this article, I present a unified framework for cancer risk management consisting of (i) a probabilistic exposure model that takes into account variability in individual exposure to the substance of concern; (ii) a probabilistic dose–response model that accounts for differences in individual cancer susceptibility; (iii) an impact assessment model that quantifies individuals’ excess lifetime cancer risk; and (iv) a welfare model that values changes in disability‐adjusted life expectancy based on workers’ willingness‐to‐pay and aggregates individual valuations across the population at risk. I illustrate the framework with data on occupational exposure to hexavalent chromium in France. In a cohort of 10,000 synthetic workers, about one third of the exposed benefit from the introduction of a binding occupational exposure limit (BOEL). Limiting hexavalent chromium exposure to the BOEL reduces the statistical worker's excess lifetime risk of fatal and nonfatal lung cancer by 4.7E‐3 and 1.5E‐3, respectively. At cohort level, the risk reduction corresponds to 738.4 full and 30.7 disability‐adjusted life years saved. The expected welfare gain of introducing the BOEL is close to €30 million. A major advantage of the framework is its ability to visualize uncertainty and variability inherent to cancer risk assessment. Notwithstanding some implementation challenges, the framework provides a transparent characterization of regulatory impacts that supports informed risk management decisions.
Overlooked biodiversity of mitochondrial lineages in Hemiodus (Ostariophysi, Characiformes)
Authors: Nogueira Acácio F. , Oliveira Claudio , Langeani Francisco , Netto‐Ferreira André L. 
Published: December 2020

AbstractHemiodus is the largest genus of the South American freshwater fish family Hemiodontidae, with 23 valid species. However, the species‐level diversity of Hemiodus remains uncertain since morphological studies have indicated additional species. Also, the phylogenetic relationships among species and species boundaries within this genus are still unresolved. Herein, we sequenced the barcode (COI) gene of 19 species of Hemiodus on which undertook molecular species delimitation methods (automatic barcode gap discovery [ABGD], generalized mixed Yule coalescent [GMYC] and Poisson tree process [PTP]) and the standard DNA barcoding procedure to establish species boundaries and cast light on putative new species in the genus. We also provide a COI‐based phylogenetic hypothesis for Hemiodus by maximum‐likelihood (ML) analysis, the first at species level. The results of ABGD, GMYC and PTP indicate that around 30 MOTUs (range: 28–32) exist for Hemiodus within our data set of 19 valid species with concordance among strategies (i.e. equal results) in delimiting 24 MOTUs. Using classical DNA barcoding procedures, we settled on 28 MOTUs for Hemiodus. Undescribed morphospecies (i.e. feasible for description or taxonomic validation), as well as cryptic species (i.e. lineages with high genetic distance but indistinguishable in external morphology), are proposed. Even with the limitations of a single‐locus phylogeny, the ML tree recovered many species and species groups as clades, corroborating, thus, their taxonomic separation. Overall, our results highlight the existence of an overlooked diversity of mitochondrial lineages in Hemiodus that can represent cryptic or poorly scrutinized species. Moreover, this study provides a molecular backbone for future studies on the systematics and evolution of Hemiodontidae taxa.
Aerothermal Optimization of Bladeless Turbines
Authors: Braun James , Paniagua Guillermo , Falempin Francois 
Published: December 2020

Abstract
The harnessing of mechanical power from supersonic flows is constrained by physical limitations and substantial aerodynamic losses. Bladeless axial turbines are a viable alternative to extract power in such harsh conditions without restricting the operating conditions. In this paper, we present a shape optimization of the wavy surface of bladeless turbines to maximize the power extraction, while minimizing convective heat flux and pressure losses. First, a baseline geometry was defined and an experimental campaign was carried out on the baseline wavy surface of the bladeless turbine at supersonic conditions. Pressure, heat flux, and skin friction measurements were compared with the Reynolds averaged Navier–Stokes results. Afterward, an evaluation routine which consisted of the geometry and grid generation, solving, and postprocessing was implemented within a multi-objective optimization routine to maximize the pressure force and minimize heat flux and pressure loss. Finally, a three-dimensional assessment in terms of power, heat load, and pressure drop was performed for the best performing geometry with the commercial solver cfd++ of Metacomp.
Multi-Objective Optimization of Wire-Electric Discharge Machined Ultrathin Silicon Wafers Using Response Surface Methodology for Solar Cell Applications
Authors: Bhartiya Divyanshu , Rana Pinal , Singh Meinam Annebushan , Marla Deepak 
Published: December 2020

Abstract
Recent investigations on the fabrication of ultrathin silicon (Si) wafers using wire-electric discharge machining (wire-EDM) were observed to possess some inherent limitations. These include thermal damage (TD), kerf-loss (KL), and low slicing rate (SR), which constraints its industrial use. The extent of TD, KL, and SR largely depends on the process parameters such as open voltage (OV), servovoltage (SV), and pulse on-time (Ton). Therefore, optimizing the parameters that pertain to minimum TD and KL while maintaining a higher SR is the key to improvement in the fabrication of Si wafers using wire-EDM. Thus, this study is an effort to analyze and identify the optimal parameters that relate to the most effective Si slicing in wire-EDM. A central composite design (CCD)-based response surface methodology (RSM) was used for optimizing the process parameters. The capability to slice Si wafers in wire-EDM was observed to be influenced by the discharge energy, which significantly impacted the overall responses. The severities of TDs were observed to be mainly dominated by the variation in OV and Ton due to the diffusion of thermal energy into the workpiece, leading to melting and subsequent resolidification. For high productivity, the optimized parameters resulted in a SR of 0.72 mm/min, TD of 17.44 μm, and a kerf-loss of about 280 μm.
Prestall Disturbances and Stall Inception for an Eccentric Low-Speed Axial Compressor With Inlet Swirl
Authors: Wang Xuegao , Hu Jun , Guo Jin , Jiang Chao , Wang Zhiqiang 
Published: December 2020

Abstract
Owing to the manufacturing and assembly error or the fatigue of long-time operation, nonaxisymmetric tip clearance is actually a common phenomenon in compressors. It is also well accepted that tip leakage flow, associated with tip clearance size and loading, has a strong influence on the performance and stall inception of compressors. The work of this paper, based on an eccentric compressor with/without inlet swirl distortion, is aimed at strengthening the understanding of stall inception for a real geometry compressor experimentally. Results indicate that rotor tip blockage and flow unsteadiness vary evidently around the circumference. For this compressor, the maximum tip flow unsteadiness and blockage happens at the location near the minimum clearance under the condition of clean inlet flow. Before the occurrence of stall inception, disturbances arise and vanish intermittently within the region of high unsteadiness. However, it fails to rotate due to the inhibition of the low unsteadiness region. Once the most robust region is no longer able to suppress disturbances, stability finally breaks down and stall inception generates. After exerting inlet paired swirl, unsteadiness within the region of positive preswirl decreases significantly and the maximum unsteadiness location shifts, while the increase for the region with negative preswirl is nearly negligible. As a result, stall margin of the compressor is improved.
Scavenge Performance of an Optimized Shallow Sump at Various Flow Conditions
Authors: Chandra Budi , Johnson Kathy 
Published: December 2020

Abstract
Oil scavenge flow in aero-engine bearing chamber remains largely a challenging problem for many engine designers. Research campaign on scavenge flow has been conducted by G2TRC—Gas Turbine and Transmissions Research Centre (previously Rolls Royce University Technology Centre in Gas Turbine Transmission Systems) at the University of Nottingham. It was recognized that a deep sump performs better than shallower one due to its ability to “shield” the collected oil in the sump from the shaft windage, thus reducing the amount of oil being picked up by the bulk air rotation. However, such a deep sump design cannot be employed in some engines and especially at certain locations where space is limited. A parametric study combined with phenomenological approach on shallow sump geometry has been conducted and presented in the previous publication, where a certain optimized shallow sump variant was proposed depending on whether the flow in the chamber is wall film dominated or airborne droplets dominated. The parametric phenomenological approach was employed since it can be done relatively quicker than typical data gathering through an experiment. However, the approach relies on qualitative interpretation of the flow features, and its application in bearing chamber flow research has never been validated before. This paper presents the results of quantitative measurements of residence volumes of an optimized shallow sump variant identified in the parametric phenomenological study. Comparison was then made with the residence volumes of some existing engine sumps. It was found that the optimized shallow sump for wall film dominated flow has lower residence volumes compared to some existing engine sumps. In some cases, the residence volume can be reduced by up to 75%. An optimized shallow sump variant for airborne droplets dominated was also identified in the previous parametric phenomenological study, although the residence volume measurement is yet to be conducted. The optimized shallow sump for wall film dominated flow was also identified as a good sump regardless of the flow regime. However, when it was tested in airborne droplets dominated flow, its residence volumes are higher than some of the existing engine sumps. This highlights the importance of considering the flow regime in the bearing chamber in any attempt to optimize a sump geometry.
Fully Coupled Turbojet Engine Computational Fluid Dynamics Simulations and Cycle Analyses Along the Equilibrium Running Line
Authors: Briones Alejandro M. , Caswell Andrew W. , Rankin Brent A. 
Published: December 2020

Abstract
This work presents fully coupled computational fluid dynamics (CFD) simulations and thermodynamic cycle analyses of a small-scale turbojet engine at several conditions along the equilibrium running line. The CFD simulations use a single mesh for the entire engine, from the intake to the exhaust, allowing information to travel in all directions. The CFD simulations are performed along the equilibrium running line by using the iterative Secant method to compute the fuel flow rate required to match the compressor and turbine power. The freestream pressure and temperature and shaft angular speed are the only inputs needed for the CFD simulations. To evaluate the consistency of the CFD results with thermodynamic cycle results, outputs from the CFD simulations are prescribed as inputs to the cycle model. This approach enables on-design and off-design cycle calculations to be performed without requiring turbomachinery performance maps. In contrast, traditional off-design cycle analyses require either scaling, calculating, or measuring compressor and turbine maps with boundary condition assumptions. In addition, the CFD simulations and the cycle analyses are compared with measurements of the turbojet engine. The CFD simulations, thermodynamic cycle analyses, and measurements agree in terms of total temperature and pressure at the diffuser–combustor interface, air and fuel mass flow rate, equivalence ratio, and thrust. The developed methods to perform CFD simulations from the intake to the exhaust of the turbojet engine are expected to be useful for guiding the design and development of future small-scale gas turbine engines.
A Review of Mooring Analysis Methodologies for Permanent Offshore Installations
Authors: Pahos Spiro J. , Maldonado Georgina , Westlake Paul C. 
Published: December 2020

Abstract
Traditionally mooring line strength assessment is based on a deterministic approach, where the mooring system is evaluated for a design environment defined by a return period. The mooring system response is then checked against the mooring strength to ensure a required factor of safety. Some codes adopt a deterministic approach [1], [2], [3]. Other codes like [4] adopt a partial safety factor format where uncertainties are addressed through load factors for load components and material factors for line strength. Industry practices give guidance on mooring analysis methodology together with analysis options like coupled, de-coupled, time domain, frequency domain and the associated line tension safety factors. Prior work has demonstrated that discrepancies in mooring line tensions are observed when different analytical approaches are used [5]. Namely, the mooring line tensions of a semi-submersible unit in a coupled time domain analysis, were found to be non-compliant, whereas those calculated using a decoupled time domain analysis returned compliant tensions.
This work focuses on a coupled dynamic analysis where all inertial, hydrodynamic and mechanical forces are assessed to determine the subsequent motions. Despite being considered the most accurate to capture the true dynamic response, a coupled analysis is also the least efficient in terms of the required computer resources and engineering effort [1].
This paper presents further discussion on the above observation in mooring tensions and also considers differences in the installation’s excursion. All responses are evaluated in the time domain where the nonlinear dynamic behavior of the mooring lines, slowly varying wave drift forces and coupling effects are captured.
Agreement is found in the present computations, carried out with two renowned hydrodynamic codes, which validate former results and reiterate the need to distinguish between time domain methods and recommended appropriate safety factors accordingly.
Experiment on the Effect of Superficial Gas-Liquid Velocities on Slug Flow-Induced Vibration in an Inclined Sagged Riser
Authors: Ma Bowen , Srinil Narakorn , Zhu Hongjun , Gao Yue 
Published: December 2020

Abstract
Subsea liquid-gas flows conveyed through a flexible riser or pipeline may develop into various flow patterns including slug flow. In this study, the slug flow-induced vibration (SIV) of an inclined sagged riser conveying upward air-water flows is experimentally investigated. A small-scale experiment is carried out in an air-water test loop with a section of a free-hanging catenary tube made of silica gel. Attention is placed on the effect of superficial gas and liquid velocities on SIV responses. Both pipe motions and flow patterns are recorded using non-intrusive high-speed cameras. Pressure variations are also measured at the pipe inlet and outlet by two pressure transducers. The SIV system is tested by employing different ratios of the superficial gas-liquid velocities. Occurrence of unstable slug flows is captured at the relatively high gas-to-liquid velocity ratios, leading to a large-amplitude SIV. Experimental results of the space-time varying riser responses and oscillation frequencies are reported together with the associated slug flow features. Depending on the gas-liquid superficial velocities, slug flow characteristics are observed to vary significantly. These entail an intermittent SIV with modulated amplitudes and frequencies along riser span, signalling a potential dynamic stress and fatigue-related concern. In all experimental cases, the riser responses are found to be multi-modal and dominated by the fundamental planar mode whereas an out-of-plane vibration is negligible. Experimental observations suggest the key interrelationships of the two-fluid flow conditions, the slug characteristics and the pipe dynamics. This finding is meaningful for a practical design of riser transporting internal multiphase flows.
1300 Tons Structural Support to Secure the Integrity of an Offshore Platform
Authors: Becerro Francisco Javier , Alonso Beatriz , De Burgh Daly Roland , Vabø Petter 
Published: December 2020

Abstract
The Yme oilfield is located approximately 100 km from the Norwegian coastline in the Egersund basin. The original field development in 2008 consisted on a jack-up type platform (MOPU) and a subsea storage tank at 93 m depth. Both are interconnected through a caisson containing all risers, piping and umbilicals which also supports a wellhead platform (WHM). That original MOPU was removed in 2016 [1] and a redevelopment of the field is currently under execution making use of some of the remaining facilities. In order to re-use the existing tank and caisson, advanced structural fatigue analyses including fracture mechanics, probabilistic assessment, motion monitoring and regular NDT inspection concluded with the requirement for a support structure to extend the service life of the old structure, which fatigue life was limited.
A screening process that covered different alternative solutions lead to a design (called Caisson Permanent Support or CPS) with overall dimensions (L.B.H) of approx. 70m × 50m × 40m and a dry-weight of 1300 t (figure 9). It consists on a beam structure composed of steel tubular braces with diameters ranging from 1,1 to 2,7 m that supports a clamp (6 m height and 5,15m diameter) connected to the caisson. In an iterative process between structural, fabrication and installation designers the optimal final concept was selected after detailed analyses to demonstrate that is capable of meeting the requirement of 20 additional years of structural service life for Yme facilities.
The CPS was successfully installed in June 2019 ensuring the integrity of the offshore structures and enabling the further re-development of the Yme field. Given its dimensions and its particular design purpose, the CPS is regarded as a unique project in the industry. This paper describes the challenges and the engineering work required for the design of the CPS.