bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of oxygen on the properties of yttrium ceramics
Authors: Nemoshkalenko V. V. , Ivanov M. A. , Klimenko G. A. , Likhtorovich S. P. , Nikitin B. G. , Nishchenko M. M. , Polotnyuk V. V. , Trachevskii V. V. , Chenakin S. P. , Pivovarov A. L. , Efimova T. V. , Morozovskii A. D.
Published: January 2025

The 60×60×60 mm3 samples of yttrium ceramics were synthesized and tested to determine their impurity content, crystallographic structure, superconducting and magnetic properties. The conditions of low-temperature thermal treatment (as compared to the conditions of synthesis) are proposed, which lead to the degradation of superconducting properties of this ceramic upon a partial removal of oxygen and to their subsequent recovery. The mechanism of copper spin paramagnetism enhancement in oxygen-deficient samples is discussed. It is established that a narrow peak ∼ 3 mrad appears in the angular distribution spectrum of annihilation photons in a partially deoxidized sample. The intensity of this peak increases in the magnetic field, which is typical of the formation of positronium states. An intense CuOH2+ emission line was observed in superconducting samples and was absent in nonsuperconducting samples.
Elastic properties of perovskite antiferromagnets of (NH3)2(CH2)nMnCI4 system
Authors: Zherlitsyn S. V. , Stepanov A. A. , Fil’ V. D. , Gall A. Le
Published: January 2025

The behavior of the velocity of sound is investigated in quasi-two-dimensional antiferromagnets of the (NH3)2(CH2)n MnCl4 (n = 3,4,5) system. According to their elastic properties, these compounds can be classified as layered materials. The Néel temperatures for this series are determined more exactly from peculiarities of the velocity of sound in the vicinity of the point of antiferromagnetic ordering. The H-T diagram is constructed for (NH3)2(CH2)3MnCl4 in magnetic fields up to 4 T.
Low-temperature phase transition in superconducting ceramics YBa2CU3O7
Authors: Eremenko V. V. , Fugol’ I. Ya. , Samovarov V. N. , Shuravlev V. M.
Published: January 2025

Temperature dependences of narrow-band cathode luminescence intensity of superconducting (SC) ceramics YBa2Cu3O7 exhibit a wide asymmetric hysteresis in the region from Tl = 30 K to Tc = 98 K. The hysteresis appears only when the sample is is cooled to below Tl = 30 K. The temperature variation rate influences the lower and upper hysteresis branches in different ways. The results are explained in terms of the concept of the first-order phase transition (PT) between two SC phases. The assumption is made concerning the kinetic blocking of a metastable phase nucleus in the range from 30 to 98 K and the stability loss in the high-temperature SC phase at 30 K.
Using simple harmonic motion to calculate the gait speed of dinosaurs
Authors: Cornish Indiah
Published: January 2025

Teaching students the physics of motion using the walking speed of sauropod dinosaurs
Advanced machine learning approach with dynamic kernel weighting for accurate electrical load forecasting
Authors: Jeevakarunya C. , Manikandan V.
Published: January 2025

This article presents a load forecasting model for commercial buildings with Enhanced Dynamically Weighted Multiple Kernel Support Vector Regression (EDW-MKSVR) and a mini-batch gradient descent method to achieve good regularization along with clustering techniques to segment different times of the day. The first step in preparing the dataset is to perform preprocessing, which involves conducting correlation analysis, scaling, and normalization followed by initial hyperparameter tuning using the multiswarm Levy flight particle swarm optimization technique. Compared with traditional methods, EDW-MKSVR offers greater adaptability to shifting load patterns since it makes use of dynamic kernel weight modifications that are dependent on data attributes. This method is used on the Commercial Buildings Energy Consumption Survey dataset, which includes information on the energy use of commercial buildings together with the climatic characteristics that are related to them across a range of periods, including the week, season, hour, and human behavior. This segmentation can be carried out using the clustering technique. In terms of performance, the study assesses the effectiveness of EDW-MKSVR models against those of boosted tree, random forest regression, K-nearest neighbor, support vector regression, and long short term memory. The study’s conclusions imply that EDW-MKSVR outperforms other current methods in terms of accuracy when obtaining complex load patterns. This article demonstrates how reliable and accurate the EDW-MKSVR approach is in predicting energy use. It facilitates the power industry’s ability to make better judgments by providing more precision and flexibility. Furthermore, the robustness of the proposed model is evaluated by predicting the electricity consumption of two additional datasets using the proposed method. Next, we compare these predictions’ performance measures, which has demonstrated the ability to generate highly ranked accuracy metrics.
Clustering time-evolving networks using the spatiotemporal graph Laplacian
Authors: Trower Maia , Djurdjevac Conrad Natasa , Klus Stefan
Published: January 2025

Time-evolving graphs arise frequently when modeling complex dynamical systems such as social networks, traffic flow, and biological processes. Developing techniques to identify and analyze communities in these time-varying graph structures is an important challenge. In this work, we generalize existing spectral clustering algorithms from static to dynamic graphs using canonical correlation analysis to capture the temporal evolution of clusters. Based on this extended canonical correlation framework, we define the spatiotemporal graph Laplacian and investigate its spectral properties. We connect these concepts to dynamical systems theory via transfer operators and illustrate the advantages of our method on benchmark graphs by comparison with existing methods. We show that the spatiotemporal graph Laplacian allows for a clear interpretation of cluster structure evolution over time for directed and undirected graphs.
Revised direct bandgap and band parameters for AlP: hybrid-functional first-principles calculations vs experiment
Authors: Murphy Cónal , O’Reilly Eoin P. , Broderick Christopher A.
Published: January 2025

Despite its relevance to the development of quantum-confined heterostructures for classical and quantum applications, there is significant uncertainty regarding several key band parameters for the indirect-gap III–V semiconductor AlP. Critically, using hybrid-functional first-principles calculations, we find that the Γ6c–Γ8v bandgap is ∼1 eV larger than the widely assumed value of 3.63 eV. This prediction is validated by using interband transition energies obtained from the hybrid-functional band structure to perform a constrained fit to spectroscopic ellipsometry data from the literature. Having validated the band structure vs experiment, we compute revised band parameters for AlP, including band edge effective masses, interband momentum (Kane) matrix elements, band edge deformation potentials, direct and indirect bandgap pressure coefficients, and natural valence band offset. Band parameters are also calculated using the Tran–Blaha modified Becke–Johnson exchange potential. Our results reconcile the spread in reported bandgaps and the conduction band valley ordering in AlP, while providing a consistent set of revised band parameters—including 8-band k · p parameters—to inform improved understanding of III-P electronic, optical, and transport properties.
Energy and exergy analyses of a spherical solar collector: Investigations of convective flows and thermal stratification
Authors: Douaouia Islam , Ould-Lahoucine Cherif
Published: January 2025

This research thoroughly investigates and models the energy and exergy efficiencies of a novel solar water heating system that includes integrated storage. The unique water heater design incorporates a spherical glass outer casing to enhance solar radiation absorption. This study evaluated three types of storage tanks: truncated conical, cylindrical, and spherical, all equipped with a top outlet and bottom intake for water circulation. A Computational Fluid Dynamic simulation in charging mode was utilized to evaluate thermal storage quality based on dimensionless numbers Richardson (Ri) and stratification (Str), energy efficiency (η), exergy efficiency (ε), and temperature profiles of eight fluid layers. At a solar radiation of 950 W m−2, the truncated cone tank has the highest thermal efficiency, reaching 0.84, while the spherical and cylindrical tanks have a thermal efficiency of 0.75 and 0.74, respectively. The findings indicate that the conical tank outperforms the other tanks in terms of both quantity and quality. Although the spherical tank is more energy-efficient than the cylindrical tank, it exhibits the lowest storage quality when the dimensionless time exceeds 0.2. Additionally, the research demonstrates how tank shape influences thermal layering and storage dynamics using a diffusion–advection equation.
An improved endwall-injection technique for examining high-temperature ignition of lubricating oils in shock tubes
Authors: Abulail Matthew , Cooper Sean P. , Mohr Darryl J. , Petersen Eric L.
Published: January 2025

Ignition of the lubricating fluid in a mechanical system is a highly undesirable and unsafe condition that can arise from the elevated temperatures and pressures to which the lubricant is subjected. It is therefore important to understand the fundamental chemistry behind its ignition to predict and prevent this condition. Lubricating oils, particularly those with a mineral oil base, are very complex mixtures of thousands of hydrocarbons. Additionally, these oils have very low vapor pressures and high viscosities. These physical characteristics present considerable barriers to examining and understanding lubricant ignition chemistry. Therefore, a novel experimental design was devised to create and introduce a lubricant aerosol into a shock-tube facility in a reliable yet relatively simple manner. In this way, the lubricant can be quasi-homogeneously introduced into the shock tube where it will be vaporized by the incident shock wave, and combustion can be observed behind the reflected shock wave. To characterize the technique and anchor it with previously established methods, n-hexadecane was chosen to be tested both with the endwall injection and the well-established, heated shock tube techniques. This comparison showed good agreement, proving the ability of the simple technique to produce reliable ignition delay time (IDT) results. From here, Jet-A was also tested with the current injection technique and compared to a previous generation of the technique to highlight the advantages of the present method. Then, IDT results for mineral oil were collected to establish a baseline IDT set to which off-the-shelf lubricants and additional mixtures can be compared. Finally, IDTs for the off-the-shelf, mineral-based lubricant Mobil DTE 732 were obtained and compared to the baseline as well as the n-hexadecane results. All experiments were conducted near atmospheric pressure and for temperatures between 1084 and 1530 K. An analysis of the system estimated the effective stoichiometry to be around ϕ = 1.15. Although no kinetics mechanisms exist for lubrication oils, preliminary model predictions made by modern chemical kinetics mechanisms for an alkane with 16 carbon atoms were then compared to the results to elucidate some of the chemistry this new method will allow the community to probe. This paper establishes the new method as a viable way to study and compare the ignition behavior of lubricating oils and other very low-vapor-pressure fuels in a shock tube.
Reliable detection of directional couplings using cross-vector measures
Authors: Brešar Martin , Andrzejak Ralph G. , Boškoski Pavle
Published: January 2025

Detecting directional couplings from time series is crucial in understanding complex dynamical systems. Various approaches based on reconstructed state-spaces have been developed for this purpose, including a cross-distance vector measure, which we introduced in our recent work. Here, we devise two new cross-vector measures that utilize ranks and time series estimates instead of distances. We analyze various deterministic and stochastic dynamics to compare our cross-vector approach against some established state-space-based approaches. We demonstrate that all three cross-vector measures can identify the correct coupling direction for a broader range of couplings for all considered dynamics. Among the three cross-vector measures, the rank-based variant performs the best. Comparing this novel measure to an established rank-based measure confirms that it is more noise-robust and less affected by linear cross-correlation. To extend this comparison to real-world signals, we combine both measures with the method of surrogates and analyze a database of electroencephalographic (EEG) recordings from epilepsy patients. This database contains signals from brain areas where the patients’ seizures were detected first and signals from brain areas that were not involved in the seizure onset. A better discrimination between these signal classes is obtained by the cross-rank vector measure. Additionally, this measure proves to be robust to non-stationarity, as its results remain nearly unchanged when the analysis is repeated for the subset of EEG signals that were identified as stationary in previous work. These findings suggest that the cross-vector approach can serve as a valuable tool for researchers analyzing complex time series and for clinical applications.
Predictive nonlinear MHD simulations of quiescent H-mode plasma in the HL-3 tokamak
Authors: Liang Z. , Hoelzl M. , Cathey A. , Hu D. , Dai S. Y. , Liu Y. L. , Wang D. Z. ,   JOREK Team
Published: January 2025

In this article, we investigate the edge localized mode (ELM)-free quiescent H (QH)-mode regime in the HL-3 tokamak via nonlinear MHD simulations. HL-3 (previously known as HL-2M) aims at high β plasmas and recently achieved its first H-mode operation. Large ELMs in H-mode discharges challenge the tolerance of plasma facing components in reactor-relevant tokamaks and small/no-ELM regimes become attractive options for existing and future fusion devices. A naturally ELM-free regime, QH-mode, is explored in this work with nonlinear extended MHD modeling for the HL-3 device. The simulation is conducted based on a realistic lower single null divertor configuration, and successfully produces a QH-mode plasma. Toroidal modes n=0,…,12 are simulated and the QH-mode plasma is dominated by a saturated n = 2 kink-peeling mode. After entering QH-mode, the plasma thermal energy becomes nearly stationary and the plasma pedestal is kept at a stable level. The saturated peeling instability produces an ergodized edge magnetic field region and some E×B convective cells, which enhance radial transport. The edge harmonic oscillation (EHO) as a characteristic feature of QH-mode plasmas is detected in the pedestal with a fundamental frequency (for the n = 1 mode) of 7.5 kHz. The EHO structures on the high-field side (HFS) and low-field side (LFS) are observed to be asymmetric. The EHO is dominated by the n = 2 mode with a frequency of 15 kHz on the HFS, while the n = 3 mode becomes dominant at the vicinity of ψnorm=0.95 on the LFS. It is also found that density and temperature profiles show different responses to the EHO in the simulation. The dependence on the safety factor for accessing QH-mode is demonstrated with the QH-mode being lost when q95 is reduced from 2.5 to 2.3. The EHO is absent in this scenario and a bursting ELM-like activity is observed instead.
p-(001)NiO/n-(0001)ZnO heterojunction devices grown by pulsed laser deposition technique
Authors: Sahu Bhabani Prasad , Kaur Amandeep , Arora Simran , Dhar Subhabrata
Published: January 2025

NiO/ZnO heterostructures are grown on c-sapphire substrates using the pulsed laser deposition technique. X-ray diffraction (XRD) study shows that the ZnO layer epitaxially grows along the [0001]-direction on the (0001)sapphire surface, as expected, while the epitaxial NiO film is found to be deposited along the [001]-direction on the (0001)ZnO surface. Moreover, the presence of three (001)NiO domains laterally rotated by 30° with respect to each other has also been confirmed by XRD and precision electron diffraction techniques in NiO layers. The study reveals the continuous nature of the NiO film, which also possesses a very smooth surface morphology. In a sharp contrast, ZnO films are found to grow along the [0001]-direction when deposited on (111)NiO layers. These films show columnar morphology. (001)NiO/(0001)ZnO layers exhibit the rectifying current–voltage characteristics that suggests the existence of p–n junctions in these devices. However, the behavior could not be observed in (0001)ZnO/(111)NiO heterojunctions. The reason could be the columnar morphology of the ZnO layer. Such a morphology can facilitate the propagation of metal ions from the contact pads to the underlying NiO layer and suppress the p–n junction effect.
Dynamical properties of the composed Logistic–Gauss map
Authors: de Paiva Luam Silva , Rocha Julia G. S. , Hermes Joelson D. V. , Hansen Matheus , Luiz Viana Ricardo , Luiz Caldas Iberê , Medrano-T Rene O. , da Costa Diogo Ricardo
Published: January 2025

This study focuses on the analysis of a unique composition between two well-established models, known as the Logistic–Gauss map. The investigation cohesively transitions to an exploration of parameter space, essential for unraveling the complexity of dissipative mappings and understanding the intricate relationships between periodic structures and chaotic regions. By manipulating control parameters, our approach reveals intriguing patterns, with findings enriched by extreme orbits, trajectories that connect local maximum and minimum values of one-dimensional maps. This theory enhances our perception of structural organization and offers valuable perceptions of the system behaviors, contributing to an expanded understanding of chaos and periodicity in dynamic systems. The analysis reveals Complex Sets of Periodicity (CSP) in the parameter space, characterized by superstable curves that traverse their main bodies. The exploration of different combinations of parameters shows cascades of CSP structures with added periods and are organized based on extreme curves. This investigation offers valuable discoveries of the dynamics of dissipative mappings, opening avenues for future explorations in chaotic systems.
Constant di/dz scanning tunneling microscopy: Atomic precision imaging and hydrogen depassivation lithography on a Si(100)-2 × 1:H surface
Authors: Mishra Richa , Moheimani S. O. Reza
Published: January 2025

We introduce a novel control mode for Scanning Tunneling Microscope (STM) that leverages di/dz feedback. By superimposing a high-frequency sinusoidal modulation on the control signal, we extract the amplitude of the resulting tunneling current to obtain a di/dz measurement as the tip is scanned over the surface. A feedback control loop is then closed to maintain a constant di/dz, enhancing the sensitivity of the tip to subtle surface variations throughout a scan. This approach offers distinct advantages over conventional constant-current imaging. We demonstrate the effectiveness of this technique through high-resolution imaging and lithographic experiments on several Si(100)-2 × 1:H surfaces. Our findings, validated across multiple STM systems and imaging conditions, pave the way for a new paradigm in STM control, imaging, and lithography.
Random walks on scale-free flowers with stochastic resetting
Authors: Li Anlin , Sun Xiaohan , Zhu Shaoxiang , Zhu Feng
Published: January 2025

This study explores the impact of stochastic resetting on the random walk dynamics within scale-free (u,v)-flowers. Utilizing the generating function technique, we develop a recursive relationship for the generating function of the first passage time and establish a connection between the mean first passage time with and without resetting. Our investigation spans multiple scenarios, with the random walker starting from various positions and aiming to reach different target nodes, allowing us to identify the optimal resetting probability that minimizes the mean first passage time for each case. We demonstrate that stochastic resetting significantly improves search efficiency, especially in larger networks. These findings underscore the effectiveness of stochastic resetting as a strategy for optimizing search algorithms in complex networks, offering valuable applications in domains such as biological transport, data networks, and search processes where rapid and efficient exploration is vital.
High-throughput material search by magnetic and compositional mapping of reactively sputtered combinatorial FexVyNz films
Authors: Fields Shelby S. , van ‘t Erve Olaf M. J. , McGrath Andrew , Johnson Francis , Bennett Steven P.
Published: January 2025

Despite the many advantages afforded to the investigation of complex compositional systems by combinatorial sputtering, the application of this synthesis technique is hindered by high-throughput characterization bottlenecks. The recent application of translatable compositional and magnetic characterization techniques, such as precision Wavelength Dispersive X-ray Fluorescence (WDXRF) and Magneto-Optic Kerr Effect (MOKE), are enabling for full wafer mapping of film chemistry, magnetic moment, and coercivity, although under-applied. An example system that stands to benefit from the application of combinatorial sputtering and high-throughput characterization is lightly nitrided FexVyNz, which, among other doped FeN materials, is a candidate rare earth-free permanent magnet for electric motor and read/write head applications. Within this report, a combinatorial sputtering and characterization procedure, which leverages high-throughput WDXRF and MOKE mapping, is utilized to investigate the effects of V composition on the room temperature ferromagnetic properties of FexVyNz. Observations made using WDXRF and MOKE mapping are shown to closely agree with vibrating sample magnetometry and x-ray photoelectron spectroscopy measurements made on cleaved regions of interest from the parent wafer. It is observed that the inclusion of V deleteriously affects the saturated moment of FeN, resulting in complete macroscopic reduction at 18 at. %. A maximum film coercivity of 165 Oe is observed at 10 at. % V, likely contributed to by crystallographic texture due to processing, followed by a complete reduction along with the saturated moment. These observations support the high-throughput characterization approaches of WDXRF and MOKE to combinatorial synthesis workflows.
Optimization of the heat transfer efficiency of a ground source heat pump heating system via FLUENT numerical simulation with fluid–solid coupling
Authors: Wei Wei
Published: January 2025

As an energy-saving and environmentally friendly technology, ground source heat pumps (GSHPs) show great potential for use in winter heating and summer cooling. However, existing systems still face the problem of insufficient heat transfer efficiency in practical applications. This study innovatively considers the influence of multiple factors, including circulating water flow, U-tube geometry, and soil thermal conductivity, on the heat transfer efficiency of GSHPs. By using FLUENT software for fluid–solid coupling simulations, we evaluated the system performance under different operating conditions, covering both the winter heating and summer cooling modes. This study revealed that the heat transfer efficiency of the system can be significantly improved by optimizing the circulating water flow, U-tube geometry, and soil thermal conductivity. In particular, the heat transfer efficiency of winter heating increased from 68.3% to 79.1%, while the heat transfer efficiency of summer cooling increased from 72.1% to 80.5%. Sensitivity analysis shows that soil thermal conductivity has the greatest impact on the heat transfer efficiency, followed by the U-tube length, U-tube diameter, and finally, the circulating water flow rate. In conclusion, a comprehensive optimization scheme is proposed, including the use of additive-modified circulating water solution to increase the heat transfer capacity, optimization of the design of U-tubes to improve the heat transfer area, improvement of soil conditions to improve thermal conductivity, and adjustment of the circulating water flow rate to achieve the optimal flow state. This study lays the foundation for the further development of GSHP systems and their wider application.
Radiation effects on pure silica and Ge-doped silica core optical fibers and fiber Bragg grating sensors
Authors: Hu Wen , Shao Chongyun , Yu Chunlei , Deng Lu , Ming Yuzhou , Ye Qing , Li Xin , Liu Yinpeng , Wei Mengda , He Dongyu , Hu Lili , Li Si-Yu , Pan Anlian , Liao Meisong
Published: January 2025

Fiber Bragg gratings (FBGs) are widely used in high-radiation environments owing to their high sensitivity, stability, and resistance to electromagnetic interference. In this study, pure and Ge-doped silica core fibers were fabricated using chemical vapor deposition. Based on these fibers, two temperature sensors, FBG-Si and FBG-Ge, were developed using femtosecond laser direct writing combined with metalized armoring. The fibers and sensors were exposed to gamma radiation, and their stability, temperature accuracy, and refractive index were systematically evaluated. Electron paramagnetic resonance and radiation-induced loss were used to investigate the effects of gamma radiation on the fiber materials and temperature sensors at the atomic micro-scale. The results showed that the Bragg center wavelength (λB) of the FBGs linearly redshifted with increasing temperature under non-stressed conditions. After gamma irradiation, at a temperature, λB, redshifted further with increasing radiation dose. The FBG-Si sensor exhibited higher stability and smaller temperature errors than FBG-Ge. Both sensors exhibited a decrease in output power after irradiation. The performance degradation of the FBGs after irradiation is attributed to an increase in the number of color centers and defects within the grating, leading to higher transmission losses. As the radiation dose increased, the concentration of the color centers increased, leading to changes in the refractive index of the gratings. This ultimately resulted in a redshift in λB and caused temperature measurement errors.
Influencing rule of accelerating flow's key parameters on unsteady aerodynamic forces of a 3:2 rectangular prism
Authors: Chen Xiu-Yu , Zhu Le-Dong , Tan Zhong-Xu
Published: January 2025

Direct measurements of aerodynamic forces on a segmental model of a rectangular section with 3:2 side ratio were conducted for varying accelerating flows. The findings indicate that the unsteady characteristic of lift force is more pronounced than that of drag force, particularly at the wind attack angle of 10°. Both the time-varying mean and dynamic components of the lift force exhibit unsteadiness at this angle. A novel approach employing the discrete wavelet packet transform is then proposed to decompose the time-varying mean and dynamic components of the lift force. Subsequently, the influencing rule of accelerating flow's key parameters on these force components is discussed and validated through comparison with the experimental data. The results highlight that the key parameters of accelerating flow governing the unsteady characteristics of lift force are starting wind velocity, average acceleration, and acceleration rising time. For the time-varying mean of lift force, the maximum inertial force is observed to increase linearly with average acceleration. Decreasing starting wind velocity and reducing acceleration rising time accentuate the magnitude of the time lag. Regarding the dynamic component of lift force, a shorter acceleration rising time and lower starting wind velocity amplify its amplitude. Additionally, the frequency of lift force is found to be lower than that predicted by the quasi-steady theory, with a reduction in acceleration rising time and starting wind velocity resulting in a further decrease in the frequency of lift force.
Electronic spectroscopy and excited state mixing of OThF
Authors: Rodriguez Arianna , Han Jiande , Yan Jiarui , Heaven Michael C. , Cheng Lan
Published: January 2025

Electronic spectra for OThF have been recorded using fluorescence excitation and two-photon resonantly enhanced ionization techniques. Multiple vibronic bands were observed in the 340–460 nm range. Dispersed fluorescence spectra provided ground state vibrational constants and evidence of extensive vibronic state mixing at higher excitation energies. Two-photon ionization measurements established the ionization energy for OThF of 6.283(5) eV. To guide the assignment of the OThF spectra, electronic structure calculations were carried out using relativistic equation-of-motion coupled-cluster singles and doubles methods. These calculations indicated that spin–orbit induced mixing of the 32A″ and 42A′ states was mediated by a seam of potential energy surface intersections.
Crystalline–disordered–crystalline transition in nitrogen–carbon materials
Authors: Devi Mamta , Pandey Prakash , Sharma Swati
Published: January 2025

Nitrogen–carbon (N–C) materials range from graphitic carbon nitride (g-CN) to graphite with nitrogen defects. Between these two crystalline extremes lies a spectrum of semi-crystalline and disordered materials. The question is whether these structural transitions are related to material’s composition, and if yes, how? Here, we answer these questions based on experimental and computational investigations on the structural evolution in N–C systems and their correlation with the chemical and electronic properties. Crystalline g-CN is used as the starting material with a systematical reduction in its N-content through heat treatment. As the N-content reduces, crystalline g-CN transitions into N-containing disordered carbons followed by N-containing graphitic carbons. The experimentally deduced electronic properties of the N–C systems with decreasing N-content are validated by theoretical methods using Density Functional Theory (DFT) approach. A qualitative match between the experimentally deduced and theoretically computed electronic properties indicate crystalline to disordered to crystalline structures in such materials at two noticeable transition points around the N/C ratios of 0.35 and 0.17, respectively.
Water transport mechanisms during pressure-driven transport through polyamide nanogaps
Authors: Vickers Riley , Weigand Timothy M. , Coronell Orlando , Miller Cass T.
Published: January 2025

Molecular-scale simulations of pressure-driven transport through polyamide nanogaps (5–100 Å) were performed to investigate fundamental transport mechanisms. Results show that transport in nanogaps ≤ 10 Å is always subdiffusive, but superdiffusive transport was observed in nanogaps ≥ 20 Å. Near typical operating pressures for applications (Δp = 100 atm), only the 100 Å nanogap exhibited superdiffusive behavior. Since openings in common membrane materials are typically <20 Å, results indicate that subdiffusive to diffusive transport dominates for typical applications, such as reverse osmosis.
Coherent structures in the flow around a pier group with scour hole
Authors: Kalidindi Murali Krishnamraju , Khosa Rakesh
Published: January 2025

Local scouring around a pier group is more complex than the one around a single pier. This study used numerical simulations to investigate the influence of coherent structures and their interactions on the development of scour hole around a pier group. The obtained results are validated with previous experimental findings. The simulations revealed that, in addition to the horseshoe vortex (HSV), other secondary vortices are present inside the scour hole. The interactions between them significantly changed the size and coherence of the HSV. The independent vortex interactions at the left and right piers led to differences in scour depth around those piers. The instantaneous velocity histograms revealed bimodal aperiodic oscillations in the HSV. The lateral movement of the detached legs of the HSV was found to be one of the reasons for the lateral expansion of the scour hole. The coherent structures are also extracted using a Lagrangian method called the Lagrangian coherent structures (LCSs). The obtained LCSs extracted the shear layers formed upstream of the pier group. They also revealed the presence of anchor-like structures upstream of the pier group within the scour hole. This study identified new mechanisms contributing to the formation of scour holes around pier groups.
Transient flow characteristics and energy loss investigation in a desalination energy recovery device under rotor system axial sliding conditions: Focusing on the turbine side
Authors: Yang Gang , Zhang Desheng , Gao Hong , Shen Xi , Pan Qiang , Pang Qingzhao , Lu Qinghui
Published: January 2025

The energy recovery integrated machine can effectively reduce the energy consumption of a seawater desalination system by harnessing the residual pressure energy in high-pressure seawater waste liquid. However, the axial force imbalance between the pump side and the turbine side can lead to axial sliding of the rotor system, and then change the axial clearance size. The objective of this paper is to investigate the unsteady flow pattern in the integrated machine with rotor system axial sliding, focusing specifically on the turbine side under coupled operation conditions. The results show that the increased axial clearance size can lead to the turbine performance decreases obviously but that of the pump side is little affected. The results of entropy production analysis show that impeller, draft tube and volute are core regions of energy loss in the turbine. The flow instability in the impeller, draft tube, and chamber is amplified by the increased axial clearance size, resulting in a greater turbulent kinetic energy dissipation. Unsteady flow phenomena such as jet, flow separation and vortex in the front chamber cause great energy loss. The dominant frequency of pressure fluctuation in the impeller is generally the axial frequency fn. The dominant frequency in the chamber is 6fn. With the increased axial clearance size, the flow instability in the clearance and the front chamber is enhanced. The increased axial clearance size results in the generation of large-scale leakage vortex in the draft tube outlet region. The dominant frequency near the wall of the draft tube gradually changes from 6fn to fn. As the axial clearance size increases, the flow instability in the draft tube is intensified by the gradual increased strength of clearance leakage vortex outside the draft tube.
The stress bifurcation and large amplitude oscillatory shear behavior of Kamani–Donley–Rogers model
Authors: Wang Pengguang , Zhou Ziyu , Liao Qingyu , Ren Huimin , Du Xu , Zhang Hongbin
Published: January 2025

Large amplitude oscillatory shear (LAOS) test has been used to elucidate the nonlinear viscoelastic behaviors of soft matter or complex fluids under large and rapid deformations encountered in production and application, especially for most polymeric materials. In this work, combined with recovery rheology, the physical visualization of the start and end yield stress values of yield stress fluids determined by the algebraic stress bifurcation (ASB) method is further interpreted in extenso. Facing the issue of unrecoverable deformations that may occur below the yield stress, the ASB method suggests the start and end yield stresses by considering the timescale, thereby linking the yield stress determination and nonlinear behavior analysis in LAOS. The unusual sharp corners in the Lissajous curves induced by the Kamani–Donley–Rogers (KDR) model are also revealed and treated by viscosity regularization. The correlation among the yield points determined by ASB and stress bifurcation, the responses of the KDR model, and corresponding results and insights by main LAOS analyses in representative cases are comprehensively discussed. This work contributes to a new understanding of stress bifurcation.
Effect of circumferential non-uniform tip clearance on the flow in a transonic compressor
Authors: Xu Jingquan , Wang Meng , Li Zheng , Song Tianchu , Wang Zhongyi
Published: January 2025

In order to clarify the influence of circumferential non-uniform tip clearance (CNTC) on the flow, this paper studies the tip clearance structures with different minimum clearance sizes and distribution forms while ensuring the consistency of the average tip clearance size. The results indicate that CNTC can directly affect the tip flow structure, and the effective structure can significantly expand the stall margin (SM). The flow structure analysis shows that CNTC mainly influences the tip leakage flow rate (TLF) and tip leakage angle (TLA). The smaller the minimum clearance size is, the smaller the TLF. The distribution of CNTC primarily affects the TLA, and a larger tip clearance size on the suction surface will result in a better flow trend. When the minimum tip clearance size is 0.5 τ and the suction surface tip clearance size is 1.5 τ, the CNTC structure achieves a SM improvement of 5.72% and a peak efficiency improvement of 0.22%. The partial CNTC results show that the modifications of each region are independent, and the direct superimposition can approximately obtain the distribution trend of the overall modification. It is more effective for the front modification, while the effect of the rear modification is weak. It is worth noting that an enlargement of the clearance on the suction surface will cause the internal flow within the clearance to be directly influenced by the shock wave, which will directly affect the modification effect.
Viscous Magnus force for a transversely rotating sphere undergoing vortex-induced vibration
Authors: Sarkar Sandip , De Arnab Kumar
Published: January 2025

We have conducted direct numerical simulations of flow past a transversely rotating sphere undergoing vortex-induced vibration. At a Reynolds number of Re=500, we have obtained results for dimensionless rotation speeds α=0.2,1 within the reduced velocity range 3≤U∗≤12, with a fixed mass ratio m∗=2. We have proposed an estimation for the viscous Magnus force on the rotating sphere, which is observed to align with the inviscid limit till U∗≈8, beyond which it grows very fast owing to the thickening of the boundary layer in the advancing side. Boundary layer separation at the top sphere surface promotes a thinner shear layer at the bottom, thereby inducing greater upwash that causes a larger Magnus force. The importance of the boundary layer thickness and their separation, thus, plays a crucial role in shaping the Magnus force at larger transverse rotation rates.
Falling film dehumidification performance on plates with various enhancing elements
Authors: Zhao Chuang-Yao , Guan Qiang , Wang Guo-Dong , Yu Tao , Zhang Fang-Fang , Qi Di , Liu Qing , Jiang Jun-Min
Published: January 2025

Enhanced heat and mass transfer in a falling film liquid desiccant dehumidifier is crucial for improving the efficiency of liquid desiccant air conditioning systems. However, no study has yet been undertaken to examine the impact of a range of different enhancing elements on dehumidification performance. This study comprehensively investigates and compares falling film hydrodynamics and dehumidification performance on plates with various enhancing elements based on different air inlet velocity and humidity, solution inlet velocity, and concentration, as well as enhancing element spacing and height. The results demonstrate that, under a variety of working conditions, the dehumidification performance of the plate with isosceles right triangle shaped finned elements (plate No. 3) is superior to that of other plates. The dehumidification performance of plates with finned elements is superior to that of plates with grooved elements under the same condition. For plates with isosceles right triangle shaped finned elements, the impact of the flow field caused by the elements is greater than in other shapes due to the greater intensity of the gas-liquid perturbation and mixing, resulting in an enhanced dehumidification performance. The findings of this study may prove valuable in the optimization of dehumidifier structures in the context of liquid desiccant dehumidification performance enhancement.
The heat–fluid–solid coupling mechanism of the optimal jet angle for high-pressure water jet erosion of aluminum
Authors: Li Mukun , Xiao Caiyun , Sun Xue , Du Yukun
Published: January 2025

A heat–fluid–solid coupling method was established to calculate the flow and stress fields, and the changes in temperature pressure fields and erosion stresses on aluminum surfaces under 100 MPa submerged water jets were studied. The results show that the impact temperature is the key factor affecting the aluminum erosion area and jet angle under viscous dissipation. The water jet can produce an impact temperature of 80 °C, and the area above 70 °C is more than ten times that of pressure above 80 MPa. The maximum tensile and shear stress under the temperature–pressure coupling field are 1.5 times and 6 times that under the pressure field, respectively. Under the pressure field, aluminum will not be destroyed, while under the temperature-pressure coupling field, aluminum will produce tensile and shear failure, and the damage radius is 4–6 times the nozzle diameter. With the jet angle increase, the impact pressure decreases, and there is no optimal non-zero jet angle for erosion stress under the pressure field. With the jet angle increase, the impact temperature increases, the 70 °C isotherm and 80 MPa isobar move close to each other, and the coupling effect of the temperature and pressure fields against erosion stress increases, and there is an optimal jet erosion angle. The optimal jet angle of maximum tensile and maximum shear stress varies from 35° to 0° and from 25° to 0°, respectively. The optimal jet angle of maximum tensile stress and shear failure area decreases with the increase in spray distance.
How words can guide our eyes
Authors: Vingron Naomi , Müller Karoza Lea Alexandra , Azevedo Nancy , Johnson Aaron , Konstantinidis Evdokimos , Bamidis Panagiotis , Võ Melissa , Kehayia Eva
Published: January 2025

Pursuing cognitively stimulating activities, such as engaging with art, is crucial to a healthy lifestyle. The
current work simulates visits to an art museum in a laboratory setting. Using eye tracking, we explored how linguistically guided
visual search may increase attention, enjoyment and retention of information when viewing art. Two groups of adults, young (under
35 years) and older (over 65 years) viewed ten paintings on a computer screen presented either with or without an accompanying
audio-guide, while having their eye movements recorded. Audio-guides referred to specific areas of the painting, marked as
Interest Areas (IA). Across age groups, as attested by gaze fixations, the audio-guides increased attention to these areas
compared to free-viewing. Audio-guided viewing did not lead to a significantly increase over free-viewing in information recall
accuracy or feelings of enjoyment and engagement. Overall, older adults did report feeling more positively about both audio-guided
and free viewing than young adults. Thus, the use of audio-guides, specifically the gamification through linguistically guided
visual search, may be a useful tool to promote meaningful attentional interactions with art.
Thermal and metaphorical meanings
Authors: Ge Yichang , Silva Fátima , Oliveira Fátima
Published: January 2025

Temperature adjectives serve as linguistic vehicles to convey sensory perceptions of physical temperature and
metaphorical extensions that resonate across various spheres of communication. Languages vary widely in their vocabulary related
to temperature, how they classify these terms, and where they fit within grammatical structures. Despite this diversity, there are
shared features in how temperature adjectives convey both temperature and metaphorical meanings across languages. However,
European Portuguese (EP) research on temperature adjectives remains scarce. To better understand temperature adjectives in EP, we
conducted a corpus-based analysis of eight adjectives -“gélido”, “gelado”, “frio”, “fresco”, “morno”, “tépido”, “quente”,
“escaldante” (icy, frozen, cold, cool, lukewarm, tepid, hot, scorching) — to investigate their literal and metaphorical meanings
using a corpus of 2920 fragments from the Reference Corpus of Contemporary Portuguese and a quantitative and qualitative approach
for the analysis. Results show that all adjectives have metaphorical meanings in addition to basic temperature interpretations,
but their distribution varies. They primarily appear post-nominally and in attributive positions, responding differently to degree
quantifiers. While the nouns with which the adjectives combine are relevant, the alternation between temperature and metaphorical
readings also depends on context.
Factores pragmáticos en el uso de los marcadores evidenciales en gallego
Authors: González Vázquez Mercedes
Published: January 2025

Este artículo pretende indagar en los factores que condicionan el uso de los marcadores evidenciales en
interacción en la lengua gallega. Tras realizar un análisis cualitativo de ejemplos tomados de dos corpus, uno del gallego actual
y otro un corpus histórico, se defiende que en la decisión del uso de expresiones evidenciales se hallan factores pragmáticos como
son la configuración del territorio de información del hablante (Kamio, 1994, 1997) y la cortesía negativa (Brown & Levinson,
1987). En lo tocante a la primera categoría, la percepción de qué información pertenece al hablante se ve influida por
tres aspectos: el grado de participación del hablante en la obtención de la información, la lejanía del contenido respecto al
campo de especialización del hablante y, por último, si el acceso al contenido enunciado es intersubjetivo. En ninguno de los tres
casos, la falta de certeza en el contenido proposicional es un componente necesario para el empleo del marcador evidencial.
Respecto a la segunda categoría, la cortesía negativa, se confirma lo que se ha demostrado en la bibliografía sobre su importancia
en la aparición de los evidenciales en situaciones de asimetría epistémica.
Actitudes lingüísticas hacia el cambio de código entre valenciano y castellano
Authors: Heredia Maite , Fernández Trinidad Marianela , Jiménez-Bravo Miguel
Published: January 2025

Este estudio constituye un primer acercamiento a las actitudes lingüísticas hacia el cambio de código que se da en una comunidad bilingüe valenciano-castellano. Los fragmentos de audio utilizados como estímulos contenían muestras de habla espontánea obtenidas del programa televisivo À Punt e incluían casos de cambio de código inter- e intraoracional. Los estímulos fueron administrados a un total de 10 jueces mediante la técnica de pares ocultos para que valorasen mediante una encuesta la competencia lingüística de los hablantes. Los resultados mostraron juicios significativamente más negativos hacia los estímulos donde el hablante empleaba el cambio de código. Además, en un análisis más detallado, se observó que, en cada una de las cuatro preguntas realizadas, otras variables como la identidad lingüística de los jueces, su género y su nivel de estudios tuvieron un efecto en las valoraciones de estos hacia el cambio de código realizado por los hablantes.
Small amplitude oscillations of a double pendulum
Authors: Cross Rod
Published: January 2025

Experimental results are presented on small amplitude oscillations of double pendulum. The results are compared with a simple expression summing the contributions of the two observed modes of oscillation.