bluuebunny/crossref_metadata_2025 huggingface dataset:
DNS of laboratory-scale turbulent premixed counterflow flames under elevated gravity conditions
Authors: Zheng Jian , Wang Haiou , Luo Kun , Fan Jianren
Published: October 2024

In the present work, direct numerical simulations (DNSs) of laboratory-scale turbulent premixed counterflow flames are performed to understand the effect of elevated gravity on flame structures. In the DNS, a turbulent jet of CH4/N2/O2 mixture is injected in opposition to a stream of combustion product. Three cases were considered, i.e., one case with normal gravity and two cases with elevated gravity in different directions. The DNS results of the case under normal gravity conditions were found to be in good agreement with the experimental data. The turbulent flame speed is the highest in the case with elevated gravity aligned with the mean flame propagating direction, which is due to the increase in flame surface area and stretch factor. The gravity levels have a substantial influence on the flame extinction characteristics. It was observed that the flame front is pushed toward the direction of the gravity. When the elevated gravity antialigns with the mean flame propagating direction, the flame front travels across the stagnation plane toward the combustion product stream, leading to significant reactant dilution and flame extinction. The flame normal vector preferentially aligns with the most compressive strain rate for various gravity conditions. The tangential strain rate is the greatest (smallest) when elevated gravity antialigns (aligns) with the mean flame propagating direction. The impact of elevated gravity on the tangential strain rate at the flame fronts ultimately leads to a displacement in the flame front location relative to the stagnation plane, thereby influencing flame extinction.
Shock wave structures and vortex unsteadiness in the tip region of a transonic turbine cascade under different conditions
Authors: Yang Yi , Ma Hongwei , Xiao Anqi , Shi Lei
Published: October 2024

The tip region of transonic turbine blades (exit Mach number of 0.95) exhibits complex flow characteristics with the coexistence of multiple shock wave systems and multiscale vortices. Based on a validated detached Eddy simulation method, unsteady flow features such as the spatial-temporal dynamic evolution of tip leakage vortices (TLV) and the periodic buffet/oscillation of shock trains inside the tip gap are revealed and discussed systematically under different incidence angles (i) and heights of tip clearance. Moreover, the distinction of tip flow structures between the subsonic and transonic conditions is also manifested. Results indicate that the wandering behavior of the TLV is influenced by both the swirling strength of the vortex itself and the interaction of adjacent secondary vortices. The TLV under a tip gap of 5% blade height (h) exhibits “binary and bimodal” wandering characteristics both along the pitchwise and spanwise direction, whereas under the 1%h case, only the pitchwise wandering is prominent. The dominant characteristic frequency of the TLV wandering under different conditions falls within the spectrum range of 2.2–2.4 kHz. As for the shock trains inside the tip clearance (τ), coherently movement back and forth along the pitchwise direction with varying amplitudes can be observed, where the magnitude within the τ=1%h exceeds that observed in the τ=5%h, depending on the intensity of the shock waves. Notably, significant shock wave oscillations are present throughout the range of the chord length (c) within the τ=1%h, whereas within the tip gap of 5%h, shock wave systems exhibit more pronounced oscillations predominantly near the trailing edge.
Characteristics of gusts with different velocity profiles and control parameters
Authors: Du Zhang-Rui , Feng Li-Hao , Wang Tong
Published: October 2024

The characteristics of gust flow are essential for gust response and alleviation. To investigate the influence of control parameters on gusts with different velocity profiles, four vertical gust profiles were designed. Methods were proposed to generate them with two pitching airfoils in a low-speed water tunnel. The velocity field was measured via phase-locked particle image velocimetry. The coefficient of determination R2 was proposed to evaluate the generated gust profile quality, which referred to the quality of the vertical velocity profile. The influence of control parameters on different gust profiles was investigated, and the cause of the profile distortion was explored. For continuous sine gusts, the gust ratio GR increased approximately linearly with the pitching amplitude, while the gust ratio initially increased and then decreased with increasing frequency. As the two control parameters increased, the flow uniformity decreased because the airfoil wakes disturbed the measured flow field. In terms of continuous 1-cosine gusts, the gust ratio increased nonlinearly with pitching amplitude. Compared with those of the sine gusts, the GR values of the 1-cosine gusts were higher, whereas the R2 values were lower. In addition, the discrete and continuous gust profiles had similar distortion near the peaks. However, discrete gusts had lower R2 values than continuous gusts because the starting and stopping vortices of the pitching airfoils disturbed the gust flow. Based on these findings, a method to improve the profile quality and field uniformity by increasing the spacing of the pitching airfoils was proposed. This work can support further studies of gust response and alleviation during complex gust encounters.
Sustenance of hydrogen–oxygen cellular detonation with ozone additions in confined space
Authors: Du Minne , Gou Pengfei , Gu Gongtian , Han Wenhu
Published: October 2024

The sustenance of cellular detonation under weak confinement is studied through two-dimensional (2D) numerical simulations of hydrogen–oxygen mixtures surrounded by inert gas. The results show that in the weakly confined space, the cellular detonation with Chapman-Jouguet velocity can survive by increasing the width of the reactant layer and enhancing the reactivity of reactants, which ensures enough triple points and high reactivity in the reactant layer for detonation sustenance since transverse shocks cannot be regenerated and reinforced by boundary reflection. By adding ozone into the system and changing the width of the reactant layer, the relationship between induction length and detonation sustenance is established. It is found that the sustenance of cellular detonation in the weakly confined space is related to the ratio of the reactant layer width to the induction length. Ozone reactions can reduce the induction length and enhance reactivity, thereby promoting the generation of new transverse shocks and significantly improving the sustenance of cellular detonation in weakly confined space.
Interaction between underwater explosion bubbles and soil–water interface: A numerical and experimental study
Authors: Yan Fu-Huai , Qiu Yan-Yu , Yue Song-Lin , Liu Lu , Wang Jian-Ping , Gao Xing-Kai
Published: October 2024

To explore the interaction between underwater explosion bubbles and soil–water interface, a near soil–water interface underwater explosion model based on the arbitrary Lagrangian–Eulerian method was established in this work. The peak pressure of the shock wave, maximum bubble radius, and bubble evolution in free-field and bottom-charge underwater explosions determined from the proposed simulation were highly consistent with the experimental results, thereby validating the proposed numerical model. The effects of the explosion distance and amount of explosive charge on the bubble–soil surface interaction were evaluated. The results showed that the reflection coefficient of the soil–water interface was in the range of 1.204–1.250, suggesting that it was hardly affected by the explosion distance and amount of explosive charge. The attenuation coefficient of the saturated soil was found to be 1.058. With the decrease in the explosion distance, the period and maximum radius of the bubbles slightly increased, and soil deformation increased as the lower surface of the bubbles was closer to the soil surface. For explosion distances of 0.3 and 0.4 m, only an overall movement of the soil surface was observed. When the explosion distance was 0.2 m or lower, a powerful downward jet was generated upon the pulsation of the first bubble, resulting in craters and slender depressions in the soil. With the increase in the amount of explosive charge, the period and maximum radius of the bubbles increased, and soil deformation also increased. These findings are expected to help advance our understanding of underwater explosion dynamics.
A novel approach to improving the interfacial strength of 3D printed Al–GNP composites by modifying GNP with MgO
Authors: Nuruzzaman Dewan Muhammad , Iqbal AKM Asif , Islam Md. Nurul , Iqbal A. K. M. Parvez
Published: October 2024

In this study, the MgO-coated graphene nanoplatelets (GNP)-reinforced aluminum matrix AlSi10Mg composites are fabricated by mechanical alloying and a 3D printing process. The interfacial structure of GNPs–Al has been investigated using high-resolution transmission electron microscopy, and their strengthening mechanism has been analyzed. A weak amorphous Al2O3 was found at the GNP–Al interface area in the composites made with uncoated GNPs. The structure of amorphous Al2O3 becomes distorted when load transfer is initiated, causing the detachment of GNPs from the matrix. This results in quick failure at the interface between uncoated GNPs and aluminum, restricting its overall strength. Once GNPs are coated with MgO, an Al/C mixing zone forms at the contact area, resulting in increased interface strength. The MgO coating on the GNP serves as a protective barrier, preventing the creation of a weaker amorphous Al2O3 layer at the interface and facilitating direct interaction between the GNP and Al matrix. The stress–strain curve demonstrates a 27.5% enhancement in tensile strength in the MgO-coated GNP–Al composite compared to the composite with uncoated GNPs. The strength is increased while maintaining toughness through load transmission of GNPs, bridging, and enhancing dislocation storage capacity by the Mg-rich phase. This study offers a new reference for strengthening 3D-printed aluminum alloys using GNPs.
Intracage vibrations and Zeeman effect in Y3N@C80 single-molecule transistors
Authors: Chen Jun , Zhu Wuwen , Xi Caigan , Zhou Yuanbiao , Shui Yuan , Qi Haoran , Liu Xinrong , Mao Yifu , Zhang Minhao , Yang Tao , Tan Yuanzhi
Published: October 2024

Clusterfullerenes, which contain a cluster rather than single-atom inclusions, exhibit more complex internal structures and greater degrees of freedom for motion. Trimetallic nitride clusterfullerenes have attracted significant attention due to their diversity and potential applications, among which Y3N@C80 stands out for its charge-transfer characteristics in electronic excitations, owing to the unique distribution of molecular orbitals near the Fermi level. Here, we have fabricated single-molecule transistor devices using Y3N@C80. Transport measurements at liquid helium temperature revealed a series of excited state energy levels, which were matched to corresponding vibrational modes through comparison with Raman spectra and density functional theory calculations. Additionally, we measured charge-state-dependent magnetic responses, revealing the electron and spin-filling patterns of the molecular orbitals in Y3N@C80. These results enhance our understanding of the dynamics and molecular spin–orbit characteristics of clusterfullerenes, indicating their potential for multifunctional applications.
Utilization of cryogenic phases of helium as “magic” working fluids in laboratory experiments: Pushing the boundaries of fluid dynamics
Authors: Skrbek L. , Niemela J. J. , Urban P.
Published: October 2024

A surprisingly large part of the valuable scientific contributions of K. R. Sreenivasan—known to his friends and coworkers as Sreeni—to fluid dynamics is directly connected with precisely controlled benchmark experiments with cryogenic phases of helium. These experiments have been performed in a number of leading low temperature laboratories using conventional viscous 4He and 3He gases, normal liquid 4He (He I), as well as liquid 3He–4He mixtures and superfluid phases of 4He (He II) and 3He-B. We review their extraordinary physical properties and describe selected experiments, focusing on various forms of thermal convection, which push the boundaries of classical and quantum fluid dynamics.
Accurate solar radiation site adaptation: Harnessing satellite data and in situ measurements
Authors: Ruiz-Munoz Jose F. , Hoyos-Gómez Laura S.
Published: October 2024

Accurate solar radiation data are essential to optimize solar energy systems and assess their feasibility. In this study, we propose a site-adaptation procedure based on a machine learning model trained to enhance the accuracy of solar radiation data using a combination of the National Solar Radiation Database (NSRDB) and in situ data collected in southern Colombia. The NSRDB provides high temporal and spatial resolution data, while in situ data offer accurate localized measurements specific to the study area. Our machine learning models were trained to learn the relationships between NSRDB data and in situ meteorological station data. The results demonstrate promising predictive capabilities, with the extreme grading boosting model effectively reducing mean absolute error, while a neural network model trained with the triplet loss function proved effective in minimizing mean bias error (MBE) and improving correlation between model-adjusted and in situ collected data. These findings make significant contributions to the field of solar radiation prediction, highlighting the effectiveness of amalgamating NSRDB and in situ data for precise solar radiation estimation, and promote the advancement of solar energy system design and decision-making processes.
Identifying the parameters of photovoltaic cells using Gaussian bare-bone imperialist competitive algorithm with opposition-based learning mechanism
Authors: Zhang Wenjun , Li Peng , Wang Hongli , Yang Wei , Lei Dongge , Wu Fei
Published: October 2024

Extracting the precise parameters of photovoltaic (PV) cells has become very important for simulation, evaluation, control, and optimization of PV systems. However, it is still a challenging task to accurately and reliably extract the parameters of PV cells. To solve this difficult problem, in this paper, a new meta-heuristic algorithm called Gaussian bare-bone imperialist competitive algorithm with opposition-based learning (OBL-GBBICA) is proposed to extract the parameters of PV cells. To strengthen the exploring ability and speed up the convergence, opposition-based learning (OBL) is introduced into an imperialist competitive algorithm (ICA) for two considerations. First, OBL is adopted in the population initialization to produce a high-quality population. Second, the OBL is introduced into the assimilation step to guide ICA to explore more promising regions. The above improvements not only speed up the convergence of ICA but also enhance its searchability, which is beneficial to improving the accuracy and reliability of identification results. Experimental results show that OBL-GBBICA exhibits great superiority in extracting the PV cells parameters, compared with other methods in the literature.
Comparing post-deposition and post-metallization annealing treatments on Al2O3/GaN capacitors for different metal gates
Authors: Schilirò Emanuela , Greco Giuseppe , Fiorenza Patrick , Panasci Salvatore Ethan , Di Franco Salvatore , Cordier Yvon , Frayssinet Eric , Lo Nigro Raffaella , Giannazzo Filippo , Roccaforte Fabrizio
Published: October 2024

Vertical Metal–Insulator–Semiconductor (MIS) capacitors with an Al2O3 thin film as a gate insulator have been fabricated on homoepitaxial GaN-on-GaN samples. The effect of the annealing treatments on the MIS characteristics has been investigated exploring two different approaches: Post-insulator-Deposition-Annealing (PDA) and Post-gate-Metallization-Annealing (PMA), i.e., annealing on the bare Al2O3 layer and annealing after the gate metallization deposition on Al2O3. The direct comparison between PDA and PMA is crucial to understand the impact of the metal/dielectric interface quality on the behavior of the Al2O3/GaN MIS capacitors. The efficacy of annealing has been monitored as a function of metal gates having different work functions: nickel (Ni), molybdenum (Mo), and tantalum (Ta). It has been found that both PDA and PMA approaches are equally able to improve the Al2O3/GaN interface electrical quality. However, the PMA demonstrates an additional beneficial effect on the metal/Al2O3 interface. In particular, the possible chemical reactions activated by the annealing process at the metal/dielectric interface can perturb the known metal/dielectric dipole responsible for Fermi-level pinning phenomena, causing a positive shift of the flat voltage (VFB), which depends on the metal, and approaching the theoretical value in the case of Mo and Ta.
Gas flows generated by pulse-periodic optical breakdown and quiet optical discharge
Authors: Androsenko V. N. , Kotov M. A. , Solovyov N. G. , Shemyakin A. N. , Yakimov M. Yu.
Published: October 2024

Quiet optical discharge in high-pressure xenon is visually stable pre-breakdown stage of optical discharge supported by pulse-periodic short-wavelength infrared laser radiation with intensity of the order of 109 W/cm2. Increasing the laser intensity leads to the transition of the quiet discharge into a pulse-periodic optical breakdown. In this study, quasi-stationary directional flows generated by both the quiet discharge and the optical breakdown are observed. The flows and their initial stages under limited number of discharge pulses are visualized by shadow imaging method using a point-like laser-plasma radiation source. It is shown that the gas streams outflow points in a quiet discharge correspond to the positions of the laser radiation intensity local maxima in the focal beam waist with astigmatism complicated by defocusing effect of thermal lens arising in the discharge zone. The pulse-periodic optical breakdown emits a turbulent gas flow toward the laser beam. The beam refraction on density gradients in the turbulent flow causes the breakdown instability from pulse to pulse. It was found that time-average absorption of laser radiation in a quiet discharge is about 3% (also in a pulse), while that in optical breakdown is 15% and higher (from 70% to 100% in a pulse). Laser beam intensity for quiet discharge at pulse repetition rate νp = 20 kHz ranges from 1.3 × 109 to 1.5 × 109 W/cm2. At intensities above 4 × 109 W/cm2 and repetition rates νp > 50–55 kHz, laser breakdowns are observed in each laser pulse with the focal ratio f/d ≤ 7. At f/d = 10.6 and νp > 28 kHz, the quiet discharge does not transit to laser breakdown due to defocusing by the thermal lens induced.
Whistler wave scattering of energetic electrons past 90°
Authors: Ma Hanqing , Drake J. F. , Swisdak M.
Published: October 2024

The consequences of a 90° barrier in the scattering of energetic electrons by whistler waves are explored with self-consistent two-dimensional particle-in-cell simulations. In the presence of a 90° scattering barrier, a field-aligned heat flux of energetic electrons will rapidly scatter to form a uniform distribution with pitch angles 0<θ<90° but with a discontinuous jump at θ=90° to a lower energy distribution of electrons with 90°<θ<180°. However, simulations reveal that such a distribution contains a large reservoir of free energy that is released to drive large-amplitude, oblique-propagating whistler waves (δB/B0∼0.1). As a result, energetic electrons near a pitch angle 90° experience strong resonance scattering. Nearly half of the energetic electrons in the positive parallel velocity plane cross the 90° barrier and diffuse to negative parallel velocities. Thus, the late-time electron velocity distribution becomes nearly isotropic. This result has implications for understanding the regulation of energetic particle heat flux in space and astrophysical environments, including the solar corona, the solar wind, and the intracluster medium of galaxy clusters.
Analyzing the inspiratory airflow unsteadiness in the respiratory tract using dynamic mode decomposition method
Authors: Jing Hao , Wang Yixiao , Wang Li , Choi Sanghun , Xi Zhaojun , Cui Xinguang
Published: October 2024

To enhance the understanding of airflow characteristics in the human respiratory tract, the inspiratory airflow field was simulated under both tidal and quasi-steady inspiratory flow rates at the mouth inlet using the large eddy simulation method. Special attention was paid on analyzing the inspiratory airflow unsteadiness using the dynamics mode decomposition (DMD) method based on the vorticity field and comparing it with the proper orthogonal decomposition (POD) method. The following novel findings were obtained. (1) Power spectral density indicates that the inspiratory airflow is highly turbulent in the pharynx–larynx region. The vorticity field in the upper airway is more affected by inspiratory patterns compared to turbulence fluctuations. (2) The DMD results indicate that the shear flow in the pharynx–larynx region is mainly caused by flow under low-frequency modes, while the disturbances of the jet flow are caused by flow under multiple frequency modes. Steady-state inspiratory pattern demonstrates the decay characteristics different from the tidal inspiratory pattern. (3) Compared to the POD method, which may contain multiple frequency components, the DMD decomposition yields modes with a single frequency, enabling a more accurate capture of the frequency and decay characteristics of the respiratory flow under each mode. In conclusion, this study demonstrates that the DMD method is more suitable for studying the respiratory airflow unsteadiness and further confirms the necessity of adopting clinically measured inspiratory data to investigate airflow unsteadiness.
Effects of sound on bluff body aerodynamic characteristics in separated and reattaching flows
Authors: Zhao Lixuan , Li Qiusheng , Wang Xincong
Published: October 2024

The coupling effects between sound and flow on the aerodynamic characteristics of bluff bodies are commonly encountered in engineering practices, such as wind turbine blades and heat exchanger compressors. This study experimentally investigates the effects of sound over a broad range of frequencies (0–400 Hz) and sound pressure levels (80–105 dB) on the streamwise wind pressures on a flat plate in both smooth and turbulent flows. Spectral analysis and proper orthogonal decomposition (POD) are employed to explore the effects of sound on the aerodynamic forces acting on the flat plate. The results show that the effects of sound on wind pressure distributions and separation bubble behaviors over the flat plate depend on both sound frequency and sound pressure level. Furthermore, the findings highlight the role of acoustic resonance, which can increase the fluctuating wind pressure on the plate surface by over 400%. These effects can also be influenced by sound pressure levels. Additionally, the results demonstrate varying degrees and forms of attenuation of sound effects in turbulent flows, depending on the wind flow characteristics.
Time-resolved cathodoluminescence measurement of the effects of
α
-particle-related damage on minority hole lifetime in free-standing n-GaN
Authors: Larkin L. S. , Ji M. , Garrett G. A. , Parameshwaran V. , Demaree J. D. , Litz M. S. , Wraback M.
Published: October 2024

Time-resolved cathodoluminescence using 30 keV ultrafast electron pulses has been used to perform direct measurements of the minority hole lifetime τh as a function of 3.7 MeV α-particle fluence in high-quality free-standing n-type GaN substrates. The lifetime damage factor K calculated from these measurements was found to monotonically decrease from 6.9 × 10−2 to 6.4 × 10−4 cm2 s−1 ion−1 with increasing α-fluence from 108 to 1012 cm−2, implying a reduction in trap cross section and/or an aggregation of α-induced traps. The small, ∼200–300 nm, hole diffusion length estimated from the minority hole lifetime for the highest α-fluence necessitates the deployment of α-voltaic device strategies and architectures that emphasize depletion and drift over diffusion for effective charge collection and optimal power conversion efficiency.
Exploring subsea dynamics: A comprehensive review of underwater pipelines and cables
Authors: Zhang Dapeng , Zhang Yi , Zhao Bowen , Ma Yunsheng , Si Kaixi
Published: October 2024

The development of marine resources is intrinsically linked to the utilization of various marine equipment. Among these, marine pipelines and cables are crucial for the exploitation of deep-sea oil and gas resources. Mooring cables, marine towed cables, marine umbilical cables, submarine cables, and marine pipelines are typical slender and flexible marine components. These slender marine flexible members present various dynamic challenges during laying, installation, and in-position operation. Facing these challenges, scholars from China and around the globe have explored theoretical, numerical, and experimental solutions to these challenges. The conclusions need to be condensed to improve their practical and academic value for engineering applications. This paper summarizes the explorations and provides general design methods and concepts of marine pipelines. Additionally, this paper looks forward to the future development trend of marine pipelines in engineering applications as well as theoretical research. The aim is to provide a reference for the research of underwater pipelines and cables.
Atomistic simulation of Na2Ti3O7: Defects, dopants, and diffusion properties
Authors: Irranious Jenevan , Iyngaran Poobalasuntharam , Abiman Poobalasingam , Kuganathan Navaratnarajah
Published: October 2024

Na2Ti3O7 exhibits promise as a safe battery material for Na-ion batteries, currently undergoing extensive research. The atomistic simulation method is employed to scrutinize defects, dopant energies, and Na-ion migration in Na2Ti3O7. Notably, the Na-Frankel energy is the lowest, and the Na-anti-site cluster energy is lower than the Na-anti-site isolated energy. The migration of Na ions is observed to predominantly occur along the ab plane, where the activation energy is measured at 0.23 eV. K and Ge ions are identified as the most suitable isovalent and tetravalent dopants for Na and Ti sites, respectively. Furthermore, the introduction of the aliovalent dopant Al3+ ion on the Ti site can form additional Na+ ions. The electronic structures of the most favorable doped configurations are discussed.
Water drop transportation on wettability switchable surface via anisotropic molecules
Authors: Chang Chia-Ming , Lin Yi-Hsin , Reshetnyak Victor
Published: October 2024

Active control of the transportation of liquid drops on a horizontal surface is achieved using surfaces with switchable wettability via remote stimuli. However, the mechanism how the dynamic wettability influences drop dynamics is rarely reported. In this paper, we demonstrate that a surface with switchable wettability induces depinning of the contact line through re-orientation of anisotropic molecules. We investigated the dynamics of contact lines and contact angles during the initiation of drop movement by the advancing and receding angles of the surface. We found that imbalance between advancing and receding angles with respect to the dynamic contact angle provides the force needed to overcome the energy barrier due to contact angle hysteresis on the surface. We discovered that the driving energy is accumulated with oscillations in contact angle until it breaks the pinning energy barrier. Understanding the role of dynamic contact angles in drop movement on switchable surfaces paves the way for designing effective fluid manipulation devices, such as water harvesters, biosensors, and oil–water separators.
Fracture propagation characteristics of water and CO2 fracturing in continental shale reservoirs
Authors: Zhang Xiaohuan , Zhang Shicheng , Zou Yushi , Li Ning , Li Jianmin , Shi Lei
Published: October 2024

Exploring the adaptability of CO2 and water-based fracturing to shale oil reservoirs is important for efficiently developing shale oil reservoirs. This study conducted fracturing experiments and acoustic emission (AE) monitoring on the Jurassic continental shale. Based on high-precision computed tomography scanning technology, digital reconstruction analysis of fracture morphology was carried out to quantitatively evaluate the complexity of fractures and the stimulation reservoir volume (SRV). The results show that the fracturing ability of a single water-based fracturing fluid is limited. Low-viscosity fracturing fluid tends to activate thin layers and has limited fracture height. High-viscosity fracturing fluid tends to result in a wide and simple fracture. A combination injection of low-viscosity and high-viscosity water-based fracturing fluid can comprehensively utilize the advantages of low-viscosity and high-viscosity fracturing fluids, effectively improving the complexity of fractures. CO2 fracturing is adaptable to Jurassic shale. The breakdown pressure of the supercritical CO2 (SC-CO2) fracturing is low. Branch fractures form, and laminas activate during SC-CO2 fracturing due to its high diffusivity. Under high-temperature and high-pressure conditions, the aqueous solution formed by mixing CO2 with water can promote the formation of complex fractures. Compared with water-based fracturing fluid, the complexity of fractures and effective stimulation reservoir volume (ESRV) increased by 8.7% and 47.6%, respectively. There is a high correlation between SRV and ESRV, and the proportion of AE shear activity is also highly correlated with the complexity of fractures. The results are expected to provide better fracturing schemes and effectiveness for continental shale oil reservoirs.
Protection efforts have resulted in ~10% of existing fish biomass on coral reefs
Authors: Caldwell Iain R. , McClanahan Tim R. , Oddenyo Remy M. , Graham Nicholas A.J. , Beger Maria , Vigliola Laurent , Sandin Stuart A. , Friedlander Alan M. , Randriamanantsoa Bemahafaly , Wantiez Laurent , Green Alison L. , Humphries Austin T. , Hardt Marah J. , Caselle Jennifer E. , Feary David A. , Karkarey Rucha , Jadot Catherine , Hoey Andrew S. , Eurich Jacob G. , Wilson Shaun K. , Crane Nicole , Tupper Mark , Ferse Sebastian C.A. , Maire Eva , Mouillot David , Cinner Joshua E.
Published: October 2024

The amount of ocean protected from fishing and other human impacts has often been used as a metric of conservation progress. However, protection efforts have highly variable outcomes that depend on local conditions, which makes it difficult to quantify what coral reef protection efforts to date have actually achieved at a global scale. Here, we develop a predictive model of how local conditions influence conservation outcomes on ~2,600 coral reef sites across 44 ecoregions, which we used to quantify how much more fish biomass there is on coral reefs compared to a modeled scenario with no protection. Under the assumptions of our model, our study reveals that without existing protection efforts there would be ~10% less fish biomass on coral reefs. Thus, we estimate that coral reef protection efforts have led to approximately 1 in every 10 kg of existing fish biomass.
Toward defining the Anthropocene onset using a rapid increase in anthropogenic fingerprints in global geological archives
Authors: Kuwae Michinobu , Yokoyama Yusuke , Tims Stephen , Froehlich Michaela , Fifield L. Keith , Aze Takahiro , Tsugeki Narumi , Doi Hideyuki , Saito Yoshiki
Published: October 2024

One of the remaining issues regarding the Anthropocene is the lack of stratigraphic evidence indicating when the cumulative human pressure from the early Holocene began to fundamentally change the Earth system. Herein, we compile anthropogenic fingerprints from various high-precision-dated proxy records for 137 global sites to determine the age of the unprecedented surge in these records over the last 7700 y. The cumulative number of fingerprints revealed an unprecedented surge in diverse anthropogenic fingerprints starting in 1952 ± 3 CE, corresponding to the onset of the Great Acceleration. Notably, the period from 1953 to 1958 CE saw a nearly simultaneous surge in fingerprints across all regions, including Antarctica, the Arctic, East Asia, Europe, North America, and Oceania. This synchronous upsurge reflects the moment when human impacts led to rapid transformations in various natural processes and cycles, with humans becoming a geological force capable of inscribing abundant and diverse anthropogenic fingerprints in global strata. Following this global fingerprint explosion, profound planetary-scale changes, including deviations from the established natural climatic conditions, begin. This unprecedented surge in anthropogenic signals worldwide suggests that human influences started to match many natural forces controlling the processes and cycles and overwhelm some of the functioning of the Earth system around 1952.
Snowmelt duration controls red algal blooms in the snow of the European Alps
Authors: Roussel Léon , Dumont Marie , Gascoin Simon , Monteiro Diego , Bavay Mathias , Nabat Pierre , Ezzedine Jade Abdellatif , Fructus Mathieu , Lafaysse Matthieu , Morin Samuel , Maréchal Eric
Published: October 2024

Algae populate multiple habitats, including snow and ice, where they can form red blooms. These decrease snow albedo, accelerating snowmelt and potentially feeding back on snow and glacier decline caused by climate change. Quantifying this feedback requires the understanding of bloom evolution with climate change. Little, however, is known about the drivers of red snow blooms. Here, we develop an algorithm to analyze 5 y of satellite data from the European Alps and separate bloom occurrences from similarly colored Saharan dust depositions. In a second step, we combine the occurrences of blooms with meteorological data and snow simulations to identify the drivers of blooms. Results show that the upward migration of algae from the ground and blooming requires the presence of liquid water throughout the whole snow column for at least 46 d. Our limited data suggest that moderate dust amounts provide nutrients favorable to bloom, whereas large dust amounts hasten snowmelt and reduce its duration below the threshold required for blooming. Over the period studied, blooms cover 1.3% of the area above 1,800 m elevation, advancing the snow melt-out date by 4 to 21 d in these areas. Under warmer climates, maximum snow mass will decrease whereas snowmelt duration, that controls algal blooms’ occurrences, is less sensitive to global temperature increase. In this respect, the impact of bloom on snowmelt will either remain stable (RCP4.5) or decrease (RCP8.5). Algal blooms in the Alps therefore do not constitute a positive climate feedback.
An engineered model of metastatic colonization of human bone marrow reveals breast cancer cell remodeling of the hematopoietic niche
Authors: Baldassarri Ilaria , Tavakol Daniel Naveed , Graney Pamela L. , Chramiec Alan G. , Hibshoosh Hanina , Vunjak-Novakovic Gordana
Published: October 2024

Incomplete understanding of metastatic disease mechanisms continues to hinder effective treatment of cancer. Despite remarkable advancements toward the identification of druggable targets, treatment options for patients in remission following primary tumor resection remain limited. Bioengineered human tissue models of metastatic sites capable of recreating the physiologically relevant milieu of metastatic colonization may strengthen our grasp of cancer progression and contribute to the development of effective therapeutic strategies. We report the use of an engineered tissue model of human bone marrow (eBM) to identify microenvironmental cues regulating cancer cell proliferation and to investigate how triple-negative breast cancer (TNBC) cell lines influence hematopoiesis. Notably, individual stromal components of the bone marrow niche (osteoblasts, endothelial cells, and mesenchymal stem/stromal cells) were each critical for regulating tumor cell quiescence and proliferation in the three-dimensional eBM niche. We found that hematopoietic stem and progenitor cells (HSPCs) impacted TNBC cell growth and responded to cancer cell presence with a shift of HSPCs (CD34+CD38−) to downstream myeloid lineages (CD11b+CD14+). To account for tumor heterogeneity and show proof-of-concept ability for patient-specific studies, we demonstrate that patient-derived tumor organoids survive and proliferate in the eBM, resulting in distinct shifts in myelopoiesis that are similar to those observed for aggressively metastatic cell lines. We envision that this human tissue model will facilitate studies of niche-specific metastatic progression and individualized responses to treatment.
Phraséologie et noms de marque
Authors: Cifuentes Natalia Soler , Grezka Aude , Flores Jorge Garcia
Published: October 2024

Dans les médias, dans la rue, sur le net… Les marques sont omniprésentes et font partie de notre quotidien. Elles quittent le
milieu marchand pour intégrer l’espace social et, à terme, elles s’insèrent dans notre lexique courant. L'objectif de notre étude est de
bâtir une base de données franco-espagnole d’unités phraséologiques avec des noms de marque afin d’analyser et de comparer les référents
culturels dans les deux langues, à la recherche d'équivalents. Nous montrerons les implications linguistiques et culturelles de ces unités
phraséologiques marginales ainsi que la méthodologie utilisée pour extraire de manière semi-automatique ces expressions grâce aux
technologies de traitement automatique du langage. Cette étude s’inscrit dans Phrasmark, un projet pluridisciplinaire alliant phraséologie
et noms de marque.
Unidades fraseológias desautomatizadas marcadas culturalmente en la traducción al español de Astérix et Obélix : Mission Cléopâtre
Authors: Harteel Kendall
Published: October 2024

Este estudio analiza las unidades fraseológicas (UF) en
Astérix et Obélix: Mission Cléopâtre
(2002) que
fueron desautomatizadas, esto es, en este caso, modificadas conscientemente a nivel del léxico para originar unidades distintas respecto
de las formas conocidas. En este trabajo se identifica y analiza desde un punto de vista cultural las UF de la película que fueron
desautomatizadas en francés para fundirse en la época del César y Cleopatra, en el 48 a.C. A partir de la traducción para la subtitulación
y el doblaje al español, se comprueba si lo que son expresiones desautomatizadas en francés también lo son en español y si se conservan o
no los elementos culturales, pues se observan tres estrategias distintas en los resultados.
De l’Antiquité à nos jours
Authors: Sánchez Jorge Valdenebro
Published: October 2024

Ce travail porte sur l’analyse diachronique de la conception des paramètres culturels du droit en traduction en Occident.
Plus spécifiquement, nous mettons l’accent sur les événements historiques ayant eu lieu dans les territoires correspondant aujourd’hui à
la France et à l’Espagne. En effet, le droit est une discipline liée à une nation précise, ce qui entraîne une composante culturelle à
prendre compte, outre les aspects juridiques à respecter. Cependant, cette vision n’a pas toujours été la même au cours de l’histoire.
Dans ce sens, notre travail vise à analyser l’évolution de la prise en considération de l’aspect culturel du droit dans les premières
réflexions et pratiques traductologiques de l’Antiquité à nos jours.
Chapter 2. The divided affective connections with the influencer
Authors: Hou Mingyi
Published: October 2024

This study explores the multimodal Chinese language discourses of an emerging type of influencers on the short video platform Douyin, the domestic counterpart of TikTok in Mainland China. Their hilarious performance is scornfully celebrated for vulgarity and absurdity. In public discussions, they are described as “pretending craziness and selling stupidity”. The analysis takes “Teacher Guo” as an example. Her funny, awkward and obscene performance, and audiences’ participation in China’s heavily regulated online space inspire the current study to adopt the theoretical lens of carnival. The study examines how audiences’ affective connections with Teacher Guo manifest through both the influencer’s and the audience’s carnivalesque semiotic practices. Findings show that Teacher Guo performs a vulgar and obscene image through her grotesque body and comic language. Audiences’ negative affective connection with her results from rejecting such social transgression: the vulgarity and obscenity are considered as a bad object in today’s wanghong culture. In contrast, the positive connection with Teacher Guo is manifested through the carnivalesque participation by those who temporarily transgress the norms of being serious, positive and polite online, thus conducting light-hearted cultural resistance with mischievous fun.
Chapter 9. Social media influencers and #DigitalDetoxDay
Authors: Beneš Kováčová Dominika
Published: October 2024

This paper presents a case study of an anti-stigma mental health campaign called Digital Detox Day, which was first organised in 2020 with the aim of encouraging people not to use social media for one day. Despite foregrounding the positive effects of digital detox, the campaign was paradoxically promoted by social media influencers (SMIs), whose popularity is contingent on an active online presence. To explore how SMIs position themselves in relation to the campaign and digital detox, a multimodal discourse analysis of 100 Instagram posts with the hashtag #DigitalDetoxDay was conducted. Having examined the functions of the multimodal semiotic resources adopted by the SMIs in this data, the paper shows that the #DigitalDetoxDay posts afford the SMIs’ self-presentation authenticity and relatability and thus do not disrupt but corroborate the characteristic image of SMIs.
Chapter 10. The construction of tellability in YouTube vlogging
Authors: Pers Mikka Lene
Published: October 2024

This chapter examines how influencers present YouTube vlogs in their thumbnail picture, caption, and description box. More specifically, it documents how mummy vlogger influencers present vlogs as worth clicking by announcing content that is presented as ‘out of the ordinary’. These announcements are counter-balanced using an authenticating strategy I have called ‘spotlight speech’. This is a clickbait strategy used by vloggers to capitalise on canonical expectations to tellability in mummy vlogging. Mummy vloggers are “entrepreneurial vloggers” (Green and Burgess 2009) who generate an income from commercial practices related to the narration of their experiences of life as a mother in ‘mummy vlogs’ (Pers 2022; Kennedy 2019; Pers 2023c). This chapter is situated within a growing body of small stories research (Georgakopoulou 2007) that examines how narrative discourse practices develop through interplay between social media platform structuration and user agency.
A unified approach for evaluation of the minimum circumscribed circle and maximum inscribed circle
Authors: Hao Xuedi , Tang Yuanzhuo , Zuo Tianlun , Li Xiuming
Published: October 2024

A unified method is proposed for evaluating the minimum circumscribed circle and maximum inscribed circle. Three initial candidate points are selected, with a one-point operator and a two-point operator. The two-point operator is also used to select candidate points or determine redundant data points during iterations. Examples from the literature confirm the effectiveness and accuracy of the proposed algorithm.
3D reconstruction and depth estimation method for local anomalies of rail surface based on multi-view stereo matching
Authors: Hu Pengyu , Zhong Qianwen , Zheng Shubin , Chen Xieqi , Peng Lele
Published: October 2024

Detecting rail surface anomalies has become crucial for ensuring the safety of train operations. However, manual detection methods are time-consuming and labor-intensive. Although traditional detection models based on one-dimensional signals or two-dimensional images can effectively identify the existence of defects, they are difficult to use to obtain local depth characteristic information, leading to difficulties in accurately assessing the extent of damage in abnormal regions. Rail track maintenance strategies are typically developed based on the detected different depth ranges of defects. To address this issue, this paper proposes a local depth estimation method based on the point cloud of the target rail surface reconstructed by PatchmatchNet. Firstly, according to the acquisition method of multi-view images and the sampling environment at the site, a practical data collection protocol is established for generating a multi-view dataset of rail surface. Next, dense point cloud of the target rail surface were reconstructed by PatchmatchNet. Subsequently, a method for estimating the local anomaly depth is developed based on the point cloud. The experimental results indicate that the proposed method achieves a maximum estimation error of only 10% within a depth range of 0.35 mm., when compared to depth measurements obtained using a structured light camera. Finally, this paper presents a more comprehensive three-dimensional representation of the local abnormal physical structure, surpassing traditional one-dimensional and two-dimensional forms. This enhanced representation offers richer information for the effective determination of whether the anomalies constitute defects and aids in distinguishing true defects from other surface irregularities. Such advancement significantly improves the precision of defect assessment and supports the development of highly precise repair strategies.
A novel performance prediction method for harmonic reducers based on the trend-enhanced Fisher’s discriminant ratio-Wiener process
Authors: Zhang Yixin , Xu Yang , Xie Guosheng , Sheng Xiaowei , Li Peibo
Published: October 2024

Harmonic reducers, as core components of industrial robots, play a critical role in maintaining robot health. Performance degradation assessment and remaining useful life (RUL) prediction are essential for ensuring the operational reliability of such robots. To address the multistage characteristics and stochastic uncertainties in the performance degradation of harmonic reducers, a performance prediction method based on Fisher’s discriminant ratio and Wiener process is proposed. Firstly, the health indicator construction is defined as an optimization problem based on Fisher’s discriminant ratio and trend monotonicity constraints. By leveraging the sum of the multiplication of frequency amplitudes and optimized weights, precise segmentation of the multistage degradation process over the entire lifecycle is achieved. Notably, the optimized weights can automatically identify the resonance frequency bands caused by damage. Subsequently, a nonlinear Wiener process model with a drift coefficient in the form of a power function is established. The probability density function expression for RUL is derived based on the concept of first hit time. Additionally, a logarithmic likelihood function for the unknown parameters in the degradation model is constructed. The experimental results indicate that the proposed method surpasses the other two Wiener process models in terms of root mean square error, mean absolute percentage error, and cumulative relative accuracy. This provides robust support for preventive maintenance decision-making for harmonic reducers.