bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Fluid Dynamics Analysis and Experimental Results for the Dynamic Performance of Two Long Smooth Surface Annular Seals Operating With a Liquid in Air Mixture
Authors: Yang Jing , Tran Dung L. , San Andrés Luis 
Published: September 2023

Abstract
Compressors in subsea oil and gas production must handle wet gases to reliably operate for extended periods of time. Annular clearance seals contribute to compressor performance and do affect system rotordynamic stability. Prior experimental work with two smooth surfaces, uniform clearance seals supplied with a light oil in air mixture and undergoing similar operating conditions produced direct stiffnesses (K) with distinct trends as the liquid content increased to 8% in volume. Both seals differ in length and diameter albeit having similar radial clearance. Other force coefficients for both seals, namely, cross-coupled stiffness (k) and direct damping (C) increase as the inlet liquid volume fraction (LVF) grows. Rationale for the peculiar differences in centering stiffness (K) is missing. Hence, a computational fluid dynamics (CFD) model and its predictions, the thrust of this paper, unveil flow field details (pressure, velocity fields, and liquid content evolution) for the oil in air mixture. Besides the CFD model, an enhanced bulk-flow model (BFM) also predicts the seals' leakage and dynamic force coefficients. Both models predict through flows agreeing well with the measured ones, the maximum difference is less than 16%. The BFM direct stiffness (K) does reproduce closely the experimental K whereas the direct damping coefficient (C) is up to ∼41% lower than the test result. The CFD model captures the variation trend of K versus inlet LVF for the first seal, albeit its magnitude is thrice the experimental stiffness. The CFD C agrees well with the test data for both seals, the largest difference is less than 10%. In spite of the complexity of the CFD model, significant differences with the experimental results persist, in particular for K. When considering the seal inlet corner as round, the CFD model produces a significant reduction in K to better approach the test result for a seal supplied with air. Attention to the seal geometry is paramount to produce accurate predictions.
A Conceptual Model for the Flutter Mechanism in Interlocked Turbine Blades
Authors: Gallardo Juan Manuel , Escobar Óscar Pérez 
Published: September 2023

Abstract
Many turbine rotor blades adopt the interlock configuration; among its advantages, there is a large increase in the natural frequencies with respect to the simpler cantilever configuration. Most widespread assessment methods estimate that this frequency increase should lead to a large improvement to the flutter stability of the interlocked rotor rows; some well-known approaches, such as the Panovsky–Kielb stability maps, suggest that flutter should be very unlikely for interlock configurations. Nevertheless, both the experience and detailed simulations indicate that it is possible to find flutter in interlocked blades, even with moderate aspect ratio. In this paper, the authors study the underlying physics behind flutter for interlocked blades, and present a very simplified model that is able to reproduce the main modal characteristics of interlocked blades, including the frequency increase and change in mode-shape as a function of the nodal diameter. This model also identifies a flutter mechanism, which is dependent on the aerodynamic interaction between the bending and torsion motion of the blade; even if both basic motions are individually stable, their interaction may lead to a coupled aeroelastic instability. The results from this simplified model are fully consistent with detailed three-dimensional linearized unsteady computational fluid dynamics simulations of representative turbine rotor blades, and should be of application in many realistic cases of interlock flutter. Finally, the authors present a study on the influence of the main parameters of the simplified model on the flutter stability, and derive some conclusions about the implications on flutter-free interlock design.
The Effect of Hydrogen on Nonlinear Flame Saturation
Authors: Æsøy Eirik , Indlekofer Thomas , Bothien Mirko R. , Dawson James R. 
Published: September 2023

Abstract
We investigate the effect of increasing levels of hydrogen enrichment on the nonlinear response and saturation of premixed bluff-body stabilized methane/hydrogen flames submitted to acoustic forcing. The thermal power is kept approximately constant to preserve the nozzle velocity while increasing the flame speed through hydrogen enrichment. The flame describing function (FDF) is measured for a fixed frequency and three hydrogen–methane blends ranging from 10% to 50% by power, corresponding to 25% to 75% by volume. We show that when the flame is forced at the same frequency at similar power and bulk velocities, increasing levels of hydrogen enrichment increase the saturation amplitude of the flame. To provide insight into the flame dynamics responsible for the change in the global nonlinear response and saturation amplitude, the flames were investigated using high-speed imaging in combination with OH planar laser-induced fluorescence (OH-PLIF) at a range of forcing amplitudes. At lower hydrogen concentrations, the flame is stabilized along the inner shear layer and saturation in the heat release rate (HRR) occurs at lower forcing amplitudes due to large-scale flame–vortex interactions causing flame annihilation as observed in several previous studies. At increased levels of hydrogen enrichment, distinctly different flame dynamics are observed. In these cases, the flame accelerates and propagates across to the outer shear layer, which acts to suppress large-scale flame annihilation during roll-up of both the inner and outer shear layers. This results in a coherent increase in flame surface area with forcing amplitudes significantly increasing the saturation amplitude of the flame. These results show that high levels of hydrogen increase the amplitude response to acoustic forcing leading to higher saturation amplitudes. This suggests that substituting natural gas with hydrogen in gas turbines increases the risk of much higher limit-cycle amplitudes if self-excited instabilities occur.
Consideration of Nonideal Detonation Regimes Influenced by Wave Modes in a Water-Cooled Rotating Detonation Engine Using OH* Chemiluminescence
Authors: Johnson Kristyn B. , Ferguson Donald H. , Weber Justin M. , Nix Andrew C. 
Published: September 2023

Abstract
Although inherently unstable, existing research in rotating detonation combustion supports its application in notionally steady processes resulting in greater availability compared to conventional, constant pressure combustion. Further improvements rely on a more in-depth understanding of system losses and identifying conditions which optimize device performance. Within this study, the presence and proportion of ideal and nonideal combustion regimes are compared across a variety of process conditions and wave modes. Large-scale data analysis seeks to summarize proportional heat release associated with commensal, parasitic, and detonative combustion averaged across individual traces of OH* chemiluminescent data acquired at the detonation plane. Means of regime partitioning based on the anatomy of the time-resolved OH* signal are proposed to ensure consistent analysis throughout the current and future studies concerning combustion regimes. Of particular interest is the possible influence of wave on the nonideal combustion in relative proportion to the desired detonation. Results showed improved percent detonation with increasing significance for the following trends: decreasing equivalence ratio, increasing wave count, decreasing wave velocity, and increasing detonation time. Increased wave number, brought on by decreased equivalence ratios and wave velocities, is thought to decrease fill region surface area, and therefore, decrease nonideal contact burning. Additional analysis is performed to consider possible trend variation due to the presence of stable galloping waves, which were found to have minimal influence on relative percent detonation values. The outcome of this study suggests operational states, which correspond to increased wave quantities for increased proportions of reactants consumed by the targeted detonative combustion regime.
Open NASA Blade Models for Nonlinear Dynamics Simulations
Authors: Kojtych Solène , Batailly Alain 
Published: September 2023

Abstract
This contribution presents a catalogue of open turbomachinery blade models dedicated to nonlinear dynamics simulations. Based on a specifically developed in-house computer code, three-dimensional computer-aided design (CAD) models and finite element (FE) models of multiple-circular-arc (MCA) NASA airfoils are generated. Both the in-house code and the models are made freely accessible online. To cover a wide range of geometries, 39 blades are considered from different stages and with different aspect ratios. It is expected that this blade catalogue will provide an opportunity for the direct comparison of recently developed methodologies relative to nonlinear vibration phenomena in turbomachines, including rubbing events and blade-tip/casing contacts. To this end, the paper also contains original results for some of the most emblematic NASA blades, with an emphasis on nonlinear interaction maps and a detailed presentation of redesign operations to mitigate high amplitude of vibrations when blade-tip/casing contacts occur.
Effect of Tip-Mounted Propeller and Trailing-Edge Flap on Wing's Lift and Drag Coefficients and Vortical Wake
Authors: Lin G. , Ni T. , Lee T. 
Published: September 2023

Abstract
The lift and drag forces and vortical wake of a rectangular semiwing equipped with a tip-mounted propeller and a plain trailing-edge flap both outside and in ground effect were investigated experimentally at Re = 2.49 × 105. Outside the ground effect, the slipstream of the inboard-up propeller rotation attenuated the wingtip vortex, significantly decreasing the lift-induced drag. The propeller rotation also led to an increased maximum lift and stall angle. At a fixed lift condition, the propeller rotation led to a reduced drag. The deployment of the flap further increased the lift curve slope and maximum lift but at the expense of an increased drag and earlier stall as compared to the unflapped wing. In ground effect, the lift augmentation of the unflapped wing increased pronouncedly with propeller rotation as the ground was approached. For the flapped wing, the propeller rotation, however, produced a smaller lift increment than the unflapped wing due to the recirculation of the deflected slipstream into the propeller disk. The extent of this recirculation increased with flap deflection and propeller rotation, contributing to the inferior lift production of the flapped wing with a tip-mounted propeller in ground effect.
Rule of Law Challenges of ‘Algorithmic Discretion’ & Automation in EU Border Control
Authors: Musco Eklund Amanda 
Published: September 2023

Abstract
The European Travel Information and Authorisation System (ETIAS) will profile visa- exempt third-country nationals using a screening rules algorithm to make automated predictive risk assessments. By using the screening rules algorithm as a case study, this article analyses if the ETIAS Regulation, and the legal safeguards it establishes for the decision-making process, comply with formal and substantive legality requirements as defined by the Venice Commission and the Court of Justice of the European Union. Three legality challenges are identified: [1] The regulatory design of ETIAS raises issues in relation to the foreseeability, clarity and accessibility of law, as well as insufficient limits to discretion. [2] The ETIAS screening rules algorithm represents a development towards a new form of arbitrariness through ‘algorithmic discretion’. [3] The safeguard of manual (human) processing in case of a ‘hit’ is not a panacea for the identified legality challenges.
Stuck in Greece? Unaccompanied Minors’ Stratified Access to Family Reunification on the Way to Other EU Member States
Authors: Melissourgos Stamatis , Leerkes Arjen , Klaassen Mark 
Published: September 2023

Abstract
We analyse the family reunification troubles of a largely overlooked category of unaccompanied minors in Europe. The unaccompanied “followers” migrate in the footsteps of primary or secondary kin, or get separated from accompanying kin during their irregular journey, and then, typically after arriving in the European Union, seek family reunification with family members living in another EU Member State. Using extensive desk research, legal analysis, and semi-structured interviews, we document a considerable ‘family reunification gap’: followers arriving in Greece often see the realisation of their reunification aspirations prevented, or much delayed, because they lack clear family reunification rights or have difficulty accessing their rights, while the – tempting – path to continued irregular family reunification is similarly full of obstacles. We also show how the interplay of legislation, implementation practices, and opportunities for irregular reunification results in family reunification hierarchy, in which the best interests of the child are unequally fulfilled.
Resisting International Norm Transfer While Seeking International Recognition – Ukrainian Asylum Lawmaking
Authors: Mützelburg Irina 
Published: September 2023

Abstract
This article contributes to the understanding of why international organisations’ attempts to transfer policies frequently fail or lead to only partial practical change in the target states. It sheds light on legislative resistance by analysing how Ukrainian lawmakers reacted to attempts to impose international asylum norms on them. Instead of overtly opposing the import of international norms, Ukrainian lawmakers resisted in a subtle way, frequently by making the implementation of the adopted norms impossible. As international normative texts contain vague formulations of certain norms, lawmakers benefited from a certain leeway when translating these norms into domestic law. They also adopted laws in a shallow way, integrating a particular norm into a very prominent law, often in a vague way, but failing to adapt other laws necessary for implementation. Finally, lawmakers delayed adoption or implementation, only making good on their commitment many years later when the pressure from international actors or incentives became too strong.
Nomi uralici e altaici di animali e uccelli in osseto
Authors: Ognibene Paolo 
Published: September 2023

Abstract
In the third part of his Ossetian studies Vsevolod Miller hypothesized that the Alans moved towards the Caucasus following a northern route, that is, without crossing the mountain ridge. In support of his hypothesis he considered the presence in the Ossetian lexicon of many names relating to the terminology of metals of Ural and Altaic origin. In order to consolidate his hypothesis, he also examined various Altaic names of animals and birds present in Ossetian. The diffusion of these names in the Caucasian area allows us to make some considerations on the period and the road through which these words entered Ossetian.
In This World or the Next: Investigation Over the “End of the World” in Contemplative Practice Through the Pāli Canon
Authors: Divino Federico 
Published: September 2023

Abstract
This article is the result of a research dedicated to the analysis of the term loka (“world”) in the Pāli canon. This work consists mainly of a translation and analysis of the Pāli suttas concerning loka and related terms. What this study reveals is a peculiar conception of the world as a cognitive construct, with a close relationship to the philosophy of mind and language. The “end of the world” (lokanta) corresponds to the state of full consciousness necessary to become a Buddha. The figure of the world ender (lokantagū) is also fundamental as a metaphor for the Buddha as an otherworldly being (lokuttara), a concept we also find in the Abhidhamma and which will form a significant part of this study. Instead of an apocalyptic vision, the idea of the end of the world seems to be the main goal of meditation in Early Buddhism and part of the Buddhist epistemological panorama.
Dissolute Libertine or Venerable Confucian?
Authors: Canale Massimiliano 
Published: September 2023

Abstract
This work aims to explore the moral conflict that many Northern Song (960–1127) scholar-officials (shidaifu 士大夫) experienced as a result of their involvement in the ci 詞 song lyric, by focusing on Ouyang Xiu’s 歐陽修 (1007–1072) collection. The song lyric was held in low regard by many exponents of high culture for several reasons, but primarily due to the fact that it exposed the literati’s relationships with courtesans. A lyricist who belonged to the Confucian elite thus found himself in a complicated position: he had to publicly advocate a moral system that was particularly conservative on matters such as sex, when he in fact privately wrote songs that would be seen as “lascivious” (yin 淫) by the very moral standards that he preached. Firstly, I will approach the problem by exploring the conflict between the Confucian ideal of sexual moderation and the diverging tendencies to sexual freedom that emerged from the practice and the poetics of the eleventh-century song lyric. I will then discuss the long critical tradition aimed at denying Ouyang Xiu’s authorship of the erotic songs attributed to him by some sources. My goal is to try to understand why so many critics espoused this view, regardless of the fact that other literati were also known to have composed rather explicit lyrics. In doing so, I shall seek to demonstrate that the attempts to dissociate Ouyang Xiu from the authorship of the “contested” erotic songs in his collection were mainly motivated by a moralistic need to preserve his reputation as a great master of the literati culture.
Parliamentary Dimension and Multilateralism
Authors: Kronlund Anna 
Published: September 2023

Abstract
Debates on the United Nations (UN) often refers to its legitimacy – its right to rule and how it is perceived. The UN and its organs, including the UN Security Council and General Assembly have been considered unrepresentative, not inclusive, and lacking democratic accountability due to the specific institutional settings and normative ideas. Different proposals have been introduced to respond to these acknowledged deficits, including the establishment of a parliamentary assembly within the United Nations following the example of the European Parliament. This article will concentrate on examining the already existing framework of having a parliamentary dimension within an intergovernmental organization, namely the UN, by recognizing the role of parliaments and parliamentarians through the UN’s cooperation with Inter-Parliamentary Union (ipu) to provide more inclusiveness to global governance. The article will contribute to the discussions of how recognizing the role of parliaments and parliamentarians could not only strengthen multilateralism but also provide for a more legitimate UN. The article covers not only the institutionalization of the cooperation between the ipu and UN but also the views of the UN member states towards parliamentary dimension in multilateral international cooperation. The article contributes to the ongoing discussions of bridging the gap between executive and legislative in international affairs and the role played by parliaments and parliamentarians in terms of supporting multilateralism.
A Comparison of the Prognostic Value of Liver Fibrosis Scores in Acute Myocardial Infarction Patients With and Without Type 2 Diabetes
Authors: He Hao-ming , Zheng Shu-wen , Chen Yi-nong , Zhu Long-yang , Wang Zhe , Jiao Si-qi , Yang Fu-rong , Sun Yi-hong 
Published: September 2023

Liver fibrosis scores have been demonstrated to be associated with poor prognosis after percutaneous coronary intervention (PCI). However, no studies have compared the prognostic value of these scores in acute myocardial infarction (AMI) patients with and without diabetes. We retrospectively enrolled 1576 AMI patients who underwent PCI. There were 177 all-cause deaths and 111 cardiac deaths during follow-up (median 3.8 years). The non-alcoholic fatty liver disease fibrosis score (NFS) showed a better prognostic value than the fibrosis-8 (FIB-8) score (Harrell’s C-index: 0.703 vs 0.671, P = .014) and the fibrosis-4 (FIB-4) score (Harrell’s C-index: 0.703 vs 0.648, P < .001) in the overall population. In the time-dependent receiver operating characteristic analysis, the NFS also had the highest area under the curve across all time points. Consistent results were observed in diabetic and non-diabetic populations. Adding the NFS to traditional cardiovascular risk factors significantly improved the prediction both for all-cause mortality (Harrell’s C-index: 0.806 vs 0.771, P < .001) and cardiac death (Harrell’s C-index: 0.800 vs 0.771, P = .014). The NFS showed a better prognostic value than the FIB-8 score and the FIB-4 score in patients with AMI undergoing PCI, which might be preferable for estimating the risk of mortality regardless of the presence or absence of diabetes.
Predictive value of transesophageal echocardiography combined with contrast transthoracic echocardiography for embolic stroke of undetermined source
Authors: Huang Wei , Wang Hebo 
Published: September 2023

Objective In this study, we aimed to assess the predictive value of transesophageal echocardiography (TEE) combined with contrast transthoracic echocardiography (cTTE) for embolic stroke of undetermined source (ESUS). Methods A total of 52 patients with ESUS were examined by TEE and cTTE. The detection rate of patent foramen ovale (PFO) and right-to-left shunt (RLS) grade were compared in patients with ESUS between cTTE alone and cTTE combined with TEE. The Risk of Paradoxical Embolism (RoPE) score, PFO diameter, and PFO length of patients with PFO-associated ESUS and non-PFO-associated ESUS were compared by cTTE alone and cTTE combined with TEE. The receiver operating characteristic (ROC) curve was utilized to determine the effect of RoPE score and PFO diameter on patients with PFO-associated ESUS. Results The positive rate of PFO detected by cTTE alone (46.15%) was lower than that detected by cTTE combined with TEE (69.23%). The proportion of patients with RLS grade I + II + III detected by cTTE combined with TEE (69.23%) was higher than that detected by cTTE alone (46.15%). Both the RoPE score and PFO diameter were significantly greater in the patients with PFO-associated ESUS than in the patients with non-PFO-associated ESUS ( p < .05). The combination of RoPE score and PFO diameter had the largest area under the ROC curve (AUC = 0.875), which was larger than the AUC alone of RoPE score (AUC = 0.819) and PFO diameter (AUC = 0.783) ( p < .05). Conclusion The combination of cTTE and TEE is helpful to the diagnosis of ESUS patients caused by PFO and to judge the degree of RLS.